CONGRESS OF THE UNITED STATES

CONGRESSIONAL BUDGET OFFICE

A

STUDY

March 2006

Alternatives for

Long-Range

Ground-Attack

Systems

CBO

The Congress of the United States O Congressional Budget Office

CBO

Alternatives for Long-Range

Ground-Attack Systems

March 2006

A

STUDY
Note

The cover shows the three types of long-range bombers in service with the United States Air 

Force. From the top: the B-2A Spirit stealth bomber (USAF photo by Master Sgt. Val 

Gempis); the B-1B Lancer (USAF photo by Master Sgt. Robert W. Valenca); and the B-52H 

Stratofortress (USAF photo by Master Sgt. Michael A. Kaplan).
Preface

The recent air campaigns in Afghanistan and Iraq highlighted the utility of long-range 

ground-attack systems. The Air Force’s fleet of B-52, B-1, and B-2 heavy bombers helped coalition forces overcome the limited availability of local air bases by operating from more distant 

bases and provided responsive air support to ground forces by orbiting over the battlefield for 

long periods of time. Recognizing those contributions, the Department of Defense (DoD) is 

in the process of developing new concepts for the role of long-range systems in future conflicts 

and is also beginning to examine new systems that could be used to attack targets anywhere in 

the world.

This Congressional Budget Office (CBO) study—prepared at the request of the Subcommittee on Strategic Forces of the Senate Committee on Armed Services—looks at the capabilities 

and costs associated with alternative long-range strike systems that DoD might develop and 

procure to improve its ability to conduct ground-attack operations. The study compares the 

advantages, disadvantages, and costs of eight alternative systems—five aircraft-based systems 

and three missile-based systems. In keeping with CBO’s mandate to provide objective, impartial analysis, this study makes no recommendations.

Robie Samanta Roy and David Arthur of CBO’s National Security Division prepared the 

study under the supervision of J. Michael Gilmore. (Robie Samanta Roy has since left CBO.) 

David Newman, Raymond Hall, and Matthew Schmit of CBO’s Budget Analysis Division 

prepared the cost estimates and wrote the appendix under the supervision of Jo Ann Vines. 

Kevin Perese and Adebayo Adedeji of CBO and Dr. Mitch Nikolich of CACI-NSR, Inc., provided thoughtful comments. (The assistance of an external participant implies no responsibility for the final product, which rests solely with CBO.)

Janey Cohen edited the study, and John Skeen proofread it. Christian Spoor edited the figures, and Leah Mazade edited the tables. Cynthia Cleveland produced drafts of the study and 

formatted the tables. Maureen Costantino designed the cover and prepared the study for publication, and Lenny Skutnik printed the initial copies.

Donald B. Marron

Acting Director

March 2006

Contents

Summary ix

1 The United States’ Long-Range Strike Capabilities 1

The Current Long-Range Strike Force 2

Capabilities for Future Long-Range Strike Systems 4

2 Alternative Designs for Long-Range Strike Systems 7

Technical Considerations for the Design of Long-Range

Strike Platforms 7

The Specific Long-Range Strike Alternatives CBO Examined 11

3 Comparing the Capabilities of the Long-Range Strike

Alternatives CBO Examined 15

Ability to Reach Targets Anywhere on Earth 16

Responsiveness 18

Sustained Firepower 23

Payload Flexibility 25

Survivability 25

4 Cost and Force-Structure Implications 27

Aircraft-Based Systems—Alternatives 1 Through 5 27

Common Aero Vehicle Systems—Alternatives 6 Through 8 33

The Relative Difficulty of Developing the Long-Range 

Strike Alternatives Considered by CBO 35

Appendix: The Methodology Behind the Cost Analysis 37
VI ALTERNATIVES FOR LONG-RANGE GROUND-ATTACK SYSTEMS

Tables

S-1. Long-Range Strike Alternatives Examined by CBO x

S-2. Estimated Costs of Long-Range Strike Alternatives Examined by CBO xv

1-1. Characteristics of Current U.S. Long-Range Bombers 3

1-2. Maximum Number of Weapons Carried on Current U.S. Long-Range Bombers 5

2-1. Long-Range Strike Alternatives Examined by CBO 8

3-1. Flight Time Needed to Reach a Target in Afghanistan 20

3-2. Examples of Target Types for Air-to-Ground Missions 25

4-1. Estimated Costs of Long-Range Strike Alternatives Examined by CBO 28

A-1. Characteristics of Supersonic Missiles for the Arsenal Aircraft (Alternative 1) 38

A-2. Acquisition Costs of Supersonic Missiles for the Arsenal Aircraft

Alternative 39

A-3. Summary of CBO’s Cost Estimating Methods for Supersonic Missiles in 

Alternative 1 40

A-4. Characteristics of Bomber Aircraft 43

A-5. Acquisition Costs of Aircraft in Alternatives 2, 3, 4, and 5 44

A-6. Summary of CBO’s Cost Estimating Methods for Aircraft in

Alternatives 2, 3, 4, and 5 45

A-7. Characteristics of Common Aero Vehicles in Alternatives 6, 7, and 8 49

A-8. Acquisition Costs of Common Aero Vehicles in Alternatives 6, 7, and 8 50

A-9. Summary of CBO’s Cost Estimating Methods for Common Aero Vehicles in 

Alternatives 6, 7, and 8 52

Figures

S-1. Response Times of Alternative Strike Systems for Preplanned Missions xiii

S-2. Number of Aircraft Needed for 24-Hour Coverage of 25 Percent of 

Afghanistan with a 10-Minute Response Time xiii

S-3. Bomb Delivery Rates for Alternative Strike Aircraft xiv

1-1. Potential Firepower of Current Air Force Strike Aircraft, Without Aerial Refueling 6

2-1. Response Times of Long-Range Common Aero Vehicles 12
CONTENTS VII

3-1. Distribution of Worst-Case Penetration Distances for Countries of the

World, Measured by Geographic or Operational Limits 16

3-2. Ability of Alternative Strike Systems to Attack Targets Deep in Enemy Territory 17

3-3. Response Times of Alternative Strike Systems for Preplanned Missions 19

3-4. Area Covered from Loitering Orbit for Different Response Times 22

3-5. Number of Aircraft Needed for 24-Hour Coverage of 25 Percent of 

Afghanistan with a 10-Minute Response Time 23

3-6. Bomb Delivery Rates for Alternative Strike Aircraft 24

4-1. Potential Firepower of Alternative Air Force Strike Forces, Without

Aerial Refueling 30

4-2. Total Potential Firepower of Alternative Bomber Forces, by Mission Distance 31

4-3. Cumulative Development and Acquisition Costs for Weapons and Their 

Delivery Systems, by Number of Weapons Used 34

Figures (Continued)

Summary

The United States maintains a considerable capability to attack ground targets with conventional weapons 

anywhere in the world. Air Force, Navy, and Marine 

Corps tactical aircraft deployed to forward locations can 

be used for ground attack, or “strike” missions, in the region where their bases or aircraft carriers are located, and 

a similar regional capability is offered by Tomahawk 

cruise missiles launched from submarines or surface 

ships. If air bases or aircraft carriers are not available in 

the region, long-range strike capability can be provided 

by the Air Force’s smaller fleet of long-range bombers, 

which can conduct missions from more-distant bases, including ones in the United States.

The performance of the bomber force in Afghanistan 

(Operation Enduring Freedom) and Iraq (Operation 

Iraqi Freedom) confirmed the value of long-range strike 

systems that are less dependent on having access to air 

bases close to the conflict. In Afghanistan, strike aircraft 

were forced to fly very long missions with extensive airborne tanker support—fighters typically had to refuel 

many times during a mission—because of basing and airspace restrictions in neighboring countries. In Operation 

Iraqi Freedom, the availability of air bases was limited, 

and the air bases in Kuwait were vulnerable to attack by 

Iraqi cruise and ballistic missiles. Although both air campaigns were successful, if air operations of greater intensity or length had been needed, those adverse circumstances might have posed problems. In contrast, longrange bombers contributed to the campaigns over great 

distances from secure bases by operating from places such 

as Diego Garcia, an island in the Indian Ocean.

Although the Air Force continues to upgrade the existing 

bomber fleet to deliver most types of conventional weapons and to participate more effectively in tactical groundattack operations, until recently there have not been definitive plans for expanding long-range strike capabilities. 

Numerous studies of which capabilities might be desired 

and several plans for potential long-range systems had 

been proposed, but none had resulted in decisions on a 

way to move forward.1 Now, however, the Department of 

Defense (DoD) has begun to define initial plans for developing new long-range strike systems. For example, the 

2006 Quadrennial Defense Review (QDR) report states 

that DoD intends to develop a new land-based longrange strike capability and to deploy an initial capability 

to deliver precision-guided conventional warheads using 

long-range ballistic missiles. However, because specific requirements for system performance and force levels have 

yet to be defined, considerable uncertainty remains as to 

which capabilities DoD will require of new long-range 

strike systems, how well different types of systems might 

provide those capabilities, and what it might cost to develop and deploy such systems.

This Congressional Budget Office (CBO) study, which 

was prepared before the release of the 2006 QDR, examines those questions. It compares how well eight longrange strike systems might perform in several areas that 

DoD studies have identified as important for future operations. Those systems reflect general classes of long-range 

weapons that have been proposed within the defense 

community and include aircraft, long-range missiles, and 

space-based weapons. Although all of the systems CBO 

examined would have the common characteristic of a 

range no less than about 1,500 nautical miles (nm)—

greater than that of current or planned strike fighters carrying typical weapon loads—their performance in other

1. See, for example, Office of the Secretary of Defense, Report to 

Congress on: Prompt Global Strike Plan (June 2005); and Department of Defense, Defense Planning Guidance: Long Range Global 

Precision Engagement Study (April 2003). 
X ALTERNATIVES FOR LONG-RANGE GROUND-ATTACK SYSTEMS

Summary Table 1.

Long-Range Strike Alternatives Examined by CBO

Source: Congressional Budget Office.

Note: CAV = common aero vehicle; n.a. = not applicable.

a. The ranges shown are the maximum distance from an air base or launcher location to the target. For the aircraft alternatives, the total 

distance flown on an unrefueled mission would be double the values shown.

b. Aircraft payloads represent combat loads; CAV payloads are per missile.

c. From an equatorial orbit, space-based CAVs could reach any point on Earth between the latitudes of 60 degrees north and 60 degrees 

south.

areas would differ substantially, as would the estimated 

costs to develop and procure them.2

To compare the military utility of different approaches 

for striking at long range, CBO used several specific measures to quantify the types of capabilities that have been 

identified for future long-range strike systems:

B Reach—the ability to attack targets regardless of

location.

B Responsiveness—the ability to attack targets quickly.

B Firepower—the ability to sustain attacks over time.

B Survivability—the ability to avoid or defeat air 

defenses.

CBO did not assess how much of the particular capabilities might be desired or needed but rather compared how 

well its alternatives (as well as today’s forces) could provide them.

Alternatives for Improving Long-Range 

Strike Capabilities

The eight alternatives examined by CBO represent very 

diverse approaches to improving long-range strike capabilities (see Summary Table 1). Each offers advantages 

and disadvantages in how it contributes to the ability to 

strike at long range.

Speed

(Mach)

1 Arsenal Aircraft 

C-17 1,500 134,000 0.76

Supersonic missile 500 n.a. 3

2 Medium-Range Subsonic Bomber 1,500 20,000 0.85

3 Medium-Range Supersonic 1,500 10,000 0.85 (Sustained)

Dash Bomber 1.5 (Dash)

4 Long-Range Subsonic Bomber 2,500 40,000 0.85

5 Long-Range Supersonic Cruise Bomber 2,500 40,000 2.4

6 Medium-Range Surface-Based CAV 3,200 2,000 14

7 Long-Range Surface-Based CAV Global 4,000 20

8 Space-Based CAV Nearly Global c 2,000 20

with Full Payloada

(Nautical miles)

Payloadb

(Pounds)

Unrefueled Range

2. Unless it is specified otherwise, an aircraft’s range in this study 

refers to its combat radius with a full load. The combat radius is 

defined here as the distance that an aircraft could fly from its base 

to attack a target and still have enough fuel to return without 

aerial refueling. The total distance the aircraft would fly on such a 

mission would be twice that range. Missile ranges are simply the 

maximum distance from the launch location to the target.
SUMMARY XI

Alternative 1 would provide for the delivery of fast missiles from a large cargo aircraft, an approach that has been 

dubbed an “arsenal aircraft” in past studies. The system 

CBO examined would consist of a new supersonic missile 

capable of flying 500 nm at Mach 3 (three times the 

speed of sound) that would be launched by C-17 cargo 

aircraft with internal rack systems from which the missiles could be extracted through the aircraft’s rear door. 

Aircraft from the planned fleet of 180 air mobility C-17s 

could carry the racks, or additional C-17s could be purchased and dedicated to the strike mission. Because cargo 

aircraft are not designed to elude air defenses, the arsenal 

aircraft itself could not penetrate hostile airspace. They 

would have to launch their missiles from secure airspace.

Alternative 2 and Alternative 3 would develop stealthy 

medium-range bombers capable of penetrating air defenses. Those aircraft would have ranges and payloads between those of today’s strike fighters and long-range 

bombers. (The now-retired F-111 is a recent example of a 

U.S. medium-range bomber.) The aircraft in Alternative 

2 would have a higher payload than that of Alternative 3 

but would be limited to subsonic speeds. The aircraft in 

Alternative 3, a concept similar to proposals for a socalled FB-22, would be capable of dash speeds up to 

Mach 1.5 for limited distances. Those aircraft could be 

designed as either manned or unmanned systems. (CBO’s 

cost estimates assume they would be manned.)

Alternative 4 and Alternative 5 would develop long-range 

bombers also capable of penetrating air defenses. Those 

aircraft would have ranges and payloads similar to those 

of today’s heavy B-52, B-1, and B-2 bombers. Alternative 

4’s aircraft would be similar in concept (although not 

necessarily in specific design) to the stealthy, subsonic B2. Alternative 5’s aircraft would be an advanced bomber 

capable of maintaining speeds greater than Mach 2 over 

most of its mission. Achieving higher speed (with a similar range and payload) than that of Alternative 4 would 

require about a 40 percent larger and heavier aircraft to 

accommodate more fuel and more powerful engines. Although probably less stealthy than the other aircraft 

alternatives—its large size and other design characteristics 

for sustained supersonic flight are not as amenable to 

stealth—the high speed of the supersonic cruise bomber 

would contribute to its survivability. Those aircraft could 

also be designed as either manned or unmanned systems. 

(CBO’s cost estimates assume they would be manned.)

Alternatives 6 through 8 would develop maneuvering 

warheads called common aero vehicles (CAVs) similar in 

concept to hypersonic systems that have been explored by 

the Defense Advanced Research Projects Agency and the 

Air Force under the FALCON (Force Application and 

Launch from the Continental United States) program. 

CAVs are missile- or spacecraft-launched unmanned vehicles capable of flying through space on suborbital trajectories. CAVs are shaped to generate sufficient lift so 

that, after reentering the atmosphere, they can glide 

many thousands of miles to their targets at hypersonic 

speeds with a combination of thrusters and flaps providing maneuvering control. CBO examined CAV systems 

that could be launched at their targets using a groundbased intercontinental ballistic missile (ICBM) or a 

smaller ground- or ship-based medium-range missile, as 

well as CAVs that would be placed in equatorial lowEarth orbits and de-orbited when needed.

The next section provides quantitative comparisons of 

the eight specific systems CBO analyzed. However, that 

analysis pointed to several general observations that can 

be made about each of the classes of systems CBO examined, independent of detailed design specifications:

Arsenal aircraft armed with supersonic missiles offer the potential to provide significant firepower and responsiveness 

at costs substantially lower than those of new penetrating 

bombers. However, their vulnerability to enemy air defenses would limit their reach into defended airspace to 

the range of the missile, a much shorter distance than 

those of the other alternatives CBO examined.

Stealthy manned or unmanned medium-range bombers

would offer reach and firepower improvements over current long-range strike fighters but would not offer the 

global reach or long loitering capability of long-range 

bombers. (Loitering in the target area enables aircraft to 

respond very quickly to fleeting targets.) A greater number of medium-range bombers could be fielded for a 

given investment, although the net firepower would not 

necessarily be higher than that of a smaller number of 

larger-payload long-range bombers.3

Stealthy manned or unmanned long-range bombers offer 

global reach and substantial sustained firepower. Subsonic 

bombers would offer global response times on the order 

3. See Chapter 4 for a comparison of the effects of purchasing different quantities of the penetrating bombers.
XII ALTERNATIVES FOR LONG-RANGE GROUND-ATTACK SYSTEMS

of 15 hours with long loitering endurance to provide fire 

against fleeting targets with response times on the order 

of several minutes. Supersonic bombers would offer 

shorter global response times but would have higher cost 

and might have a limited ability to loiter.

Hypersonic CAVs—either space-based or launched by ballistic missiles—would offer responsiveness on the order of 

one hour against targets anywhere on the globe and 

would be the most difficult systems for enemy defenses to 

intercept. However, their high unit cost implies that they 

probably could not be purchased in sufficient numbers to 

provide the sustained firepower offered by aircraft forces.

Comparison of Long-Range Strike 

Alternatives Considered by CBO

The long-range strike systems examined by CBO would 

provide diverse capabilities, with each alternative offering 

advantages and disadvantages for different types of missions. In addition to differences in capability, the alternatives would have unique implications for the future force 

structure. Fielding CAVs, for example, would provide a 

new rapid-strike capability but would not address the issue of the aging bomber force. Conversely, a supersonic 

bomber could replace today’s bombers but would offer 

less responsiveness than CAVs would. Because of such 

distinctions, the alternatives CBO examined should not 

necessarily be viewed as independent alternatives. Depending on the specific requirements that DoD eventually establishes for its long-range strike systems, the preferred solution might include more than one of the 

systems CBO examined.

Capabilities

In comparing the capabilities of the alternative longrange strike systems, CBO examined how far each system 

could reach, how responsive it would be in several settings, how much firepower it could provide, and how 

safely it could operate in the face of enemy air defenses.

Reach. The reach of a long-range strike system can be important for two reasons. First, long range allows missions 

to be conducted from greater distances, either before local 

bases can be established or when they are not available. 

Aerial refueling, however, means that even short-range 

aircraft can fly missions much longer than their “unrefueled range” would allow. Consequently, all of CBO’s alternatives would offer the potential for global reach. 

Nonetheless, the two long-range CAVs and the two longrange bombers would be best suited for missions requiring global reach. The medium-range bomber alternatives 

could, in principle, be used for intercontinental missions, 

but the need for more frequent refueling would complicate operations, and crew endurance in the probably 

cramped confines of a small cockpit might present problems. The C-17 arsenal aircraft could carry relief crews to 

help remedy that problem, but it would still require more 

frequent refueling than would the long-range bomber alternatives. Although lacking inherent global reach, the 

medium-range CAV alternative could cover most of the 

globe from just a few forward land bases (for example, 

Guam in the western Pacific Ocean and Diego Garcia, a 

territory of Great Britain in the Indian Ocean) or ships.

A second facet to the military value of long range is the 

capability it offers to reach targets deep in hostile airspace, where support from airborne tankers would not be 

available. That can be important against larger countries 

or in situations where tanker operations are otherwise 

constrained. All of the alternatives CBO examined except 

the arsenal aircraft provide very good capability to reach 

any point within all or most countries in the world. The 

long-range bombers and the long-range surface-based 

CAV could do so for all countries. The medium-range 

bombers could do so for 95 percent of all countries under 

conservative assumptions about access to airspace adjacent to the target country. Easing those assumptions 

slightly would enable full coverage. The medium-range 

CAV could fully cover all countries given suitable launch 

locations. The space-based CAV could fully cover almost 

all countries (about 97 percent of them) from its equatorial orbit. The exceptions are those countries with territory at North or South latitudes greater than about 60 degrees. The arsenal aircraft, carrying a supersonic missile 

with a range of 500 nm after launch, would provide the 

least coverage. If the C-17 delivering the missile must 

stand off outside hostile airspace, it could fully cover only 

about 75 percent of the world’s countries.4

4. This geography-based analysis does not distinguish among nations 

that are more or less likely to be considered potential threats. Such 

judgments are subjective and change over time. For three nations 

commonly mentioned as potential adversaries—North Korea, 

Iran, and China—the CAV and long-range bomber alternatives 

would provide total coverage, the medium-range bombers could 

not reach parts of China, and the supersonic air-launched missile 

could not reach parts of Iran and China.
SUMMARY XIII

Summary Figure 1.

Response Times of Alternative Strike 

Systems for Preplanned Missions

(Hours to strike target)

Source: Congressional Budget Office.

a. The steps in the line for the supersonic cruise bomber result 

from its need to slow for aerial refueling.

b. Response times for the common aero vehicle alternatives will 

vary for a given distance to the target, depending on the specific 

flight profile needed. The medium-range common aero vehicle 

has a maximum distance to target of 3,200 nautical miles.

Responsiveness. CBO considered responsiveness in two 

contexts: preplanned missions that would require responsiveness on the order of hours, and fleeting-target or 

ground-support missions that would require response 

times on the order of a few minutes. Assuming a similar 

planning process, a system’s speed will be the primary determinant of its responsiveness in a preplanned mission. 

The greater the distance to be traveled, the greater the cumulative advantage of higher speed (see Summary 

Figure 1). The hypersonic CAV alternatives, consequently, would offer by far the shortest response times 

among CBO’s alternatives. The long-range supersonic 

cruise bomber (Alternative 5) would have a response time 

between that of the CAVs and the other aircraft alternatives. The medium-range supersonic bomber would not 

be significantly more responsive than the subsonic aircraft 

because it could not maintain supersonic speed during 

the entire transit to its target.

Against fleeting targets or in a ground-support role, none 

of the long-range strike alternatives would provide, from 

a standing start, response times on the order of a few 

minutes. Even a space-based CAV would need at least 15 

minutes if the launcher was in the right orbital location 

and no atmospheric maneuvering was necessary. Very 

short response times require maintaining systems close to 

the locations where targets are expected to appear, a tactic 

that could not be accomplished with the CAV alternatives. For the other alternatives, the area that can be covered by an aircraft orbiting over a particular location for a 

given response time and the number of aircraft needed to 

maintain such orbits become the critical factors. (See 

Chapter 3 for a more detailed discussion.) From that perspective, the arsenal aircraft would provide the shortest 

response times with the fewest aircraft because the Mach 

3 missile it would employ can dash much farther in a

Summary Figure 2.

Number of Aircraft Needed for

24-Hour Coverage of 25 Percent of 

Afghanistan with a 10-Minute 

Response Time

Source: Congressional Budget Office.

Note: This figure assumes that an aircraft expends all of its munitions before returning to base. Endurance would be lower if 

an aircraft returned with unused munitions.

0

5

10

15

20

25

0 2,000 4,000 6,000 8,000 10,000

Common Aero Vehiclesb

Arsenal Aircraft

Medium-Range

Bombers and

Long-Range

Subsonic Bomber Long-Range

Supersonic

Cruise Bomber

Nautical Miles to Target

a

0

20

40

60

80

100

0 500 1,000 1,500 2,000 2,500

Medium-Range

Supersonic

Dash Bomber

Medium-Range

Subsonic

Bomber

Arsenal

Aircraft

Long-Range

Subsonic

Bomber

Nautical Miles Between Base and Orbit Location
XIV ALTERNATIVES FOR LONG-RANGE GROUND-ATTACK SYSTEMS

Summary Figure 3.

Bomb Delivery Rates for Alternative 

Strike Aircraft

(Number of 2,000-pound JDAM-equivalents per aircraft

per day)

Source: Congressional Budget Office.

Note: Data are shown out to the unrefueled radius of each type of 

aircraft when carrying a full bomb load. All alternatives could 

achieve greater ranges with aerial refueling or reduced 

bomb loads.

JDAM = Joint Direct Attack Munition.

given amount of time than can the other aircraft alternatives (see Summary Figure 2). The long-range subsonic 

bomber (Alternative 4) would offer good performance 

because of its long endurance, especially for orbits far 

from base or far from aerial refueling support. Performance of the medium-range bomber alternatives suffers 

from the lack of the supersonic missile’s high speed (Alternative 1) and the long-range subsonic bomber’s endurance (Alternative 4), although the supersonic dash capability of Alternative 3 gives it good performance for orbits 

close to base. The supersonic cruise bomber could not 

meet the responsiveness criteria in Summary Figure 2 because CBO assumed its design would not be suitable for

maintaining sustained low-speed orbits.

Firepower. Another requirement for long-range strike 

systems will probably be support of operations requiring 

the delivery of a high volume of munitions such as those 

seen in large conflicts. Long-range systems could be especially important early in those situations, before significant numbers of tactical aircraft have been deployed to 

the theater. Because of their large payloads, the arsenal 

aircraft and the long-range subsonic bomber (Alternatives 

1 and 4) would offer the highest per-platform weapon delivery rates for mission distances of less than 2,400 nm 

(see Summary Figure 3). For mission distances of longer 

than 2,400 nm, the supersonic cruise bomber’s speed 

would provide it an advantage in firepower despite the 

longer time needed to prepare it for each mission.5

The number of systems purchased also affects the achievable firepower. Although Alternative 1 can physically 

achieve a high weapon delivery rate, the relatively high 

cost of each supersonic missile—about $1.4 million per 

round as compared with about $31,000 for a satelliteguided bomb such as the Joint Direct Attack Munition 

(JDAM)—may ultimately constrain its use. CBO did not 

include the CAV alternatives in the firepower comparison 

because their much higher unit costs would almost certainly make them unsuitable for such sustained operations. Similarly, the number of aircraft purchased under a 

given alternative would affect the forcewide weapon delivery capability. For example, an additional 25 mediumrange subsonic bombers (for a total of 300) would provide similar firepower (albeit over shorter distances) as the 

150 long-range bombers under Alternative 4 but for 

about $19 billion less. In contrast, 600 medium-range supersonic bombers would be needed to provide an equivalent firepower at a cost of about $38 billion more than 

that for 150 long-range subsonic bombers.

Survivability. The ability to reach the target—and, in the 

case of aircraft, return safely—in the face of air defenses is 

important for long-range strike systems because they will 

most likely be tasked in circumstances where the timely 

suppression of enemy air defenses will not be possible. 

The CAV alternatives examined by CBO would have the 

greatest survivability. After launch, their hypersonic 

speeds and ability to maneuver unpredictably could only 

be countered by a very sophisticated missile defense sys0

20

40

60

80

0 500 1,000 1,500 2,000 2,500

Long-Range

Supersonic

Cruise Bomber

Medium-Range

Subsonic Bomber

Arsenal Aircraft

Long-Range

Subsonic

Bomber

Medium-Range

Supersonic

Dash Bomber

Nautical Miles to Target

5. CBO assumed that the greater complexity of a supersonic cruising 

aircraft and the greater rigors of sustained supersonic flight would 

result in servicing times between missions of about twice the 

length of the long-range subsonic-bomber alternative.
SUMMARY XV

Summary Table 2.

Estimated Costs of Long-Range Strike Alternatives Examined by CBO

Source: Congressional Budget Office.

Note: RDT&E = research, development, test, and evaluation; CAV = common aero vehicle.

a. The costs for Alternatives 2 to 5 exclude munitions.

b. Includes additional military construction costs of about $1 billion for the aircraft alternatives (2 to 5) and $600 million for Alternative 7.

c. The quantity shown is the number of supersonic missiles purchased. The lower of the two costs assumes that those missiles would be carried by C-17 aircraft in the current fleet. The higher of the two costs assumes that 15 additional C-17s would be purchased to support the 

strike mission.

d. Average unit procurement cost is for supersonic missiles only.

e. Alternative 7 assumes that 24 Peacekeeper missiles would be converted to carry two CAVs per missile. If more missiles were desired, as 

many as 60 Peacekeepers might be available for conversion. The cost of additional missiles would be much higher than the cost shown 

here because new boosters would be needed.

f. Enough satellites would be purchased to maintain the constellation for 30 years. Only 40 space-based CAVs would be available for use at 

any one time.

tem. Attacking CAVs before they were launched would 

be difficult as well: survivable long-range systems would 

be needed to hit the surface-based CAV systems, and an 

antisatellite capability would be needed against orbiting 

CAVs. In the case of the arsenal aircraft, although the supersonic air-launched missile would also be a challenge 

for air defenses, its C-17 delivery platform could be vulnerable if an adversary was able to send fighters out to intercept it. The stealth designs for the subsonic bombers, 

Alternative 2 and Alternative 4, should give them good 

survivability against ground-based air defenses and 

against fighters at night. They could be vulnerable to 

fighters during the day, however, when the bombers 

could be detected visually. The long-range supersonic 

cruise bomber has a combination of limited stealth and 

high speed that should enable it to avoid engagement by 

many surface defenses and to outrun fighters sent to intercept it. Similarly, the medium-range bomber in Alternative 3 could use stealth to survive surface defenses and 

its supersonic dash speed to elude fighters, although with 

less certainty because it would have less of a speed advantage than the supersonic cruise bomber would.

Cost and Force-Structure Implications

Comparing the long-range strike alternatives is complicated by the significant differences in the estimated costs 

1 Arsenal Aircraft 2,000 c 1.5 2.8/6.1 c 4.3/7.6 c 1.4 d

2 Medium-Range Subsonic

Bomber 275 19 52 72 188

3 Medium-Range Supersonic

Dash Bomber 275 23 61 85 220

4 Long-Range Subsonic Bomber 150 31 61 93 409

5 Long-Range Supersonic

Cruise Bomber 150 69 137 207 912

6 Medium-Range SurfaceBased CAV 48 2.4 1.2 3.7 26

7 Long-Range Surface-Based CAV e 24 2.5 0.9 4.0 36

8 Space-Based CAV 128 f 4.0 7.7 11.7 55

RDT&E Procurement

Costsa

Quantity

Average Unit Procurement Cost

Total (Millions of 2006 dollars) b

(Billions of 2006 dollars)
XVI ALTERNATIVES FOR LONG-RANGE GROUND-ATTACK SYSTEMS

to develop and field them (see Summary Table 2). CBO 

estimates that research, development, test, and evaluation 

(RDT&E) costs could vary by more than an order of 

magnitude among the alternatives, with the arsenal aircraft and CAV alternatives costing the least and the advanced supersonic cruise bomber the most. Similarly, estimates of production costs also vary over a broad range, 

although the differences among alternatives are in part 

the result of assumptions about how many of each type of 

system would be purchased. The cost estimates are presented in 2006 dollars. Significant uncertainty exists 

about the costs associated with developing, purchasing, 

and operating weapon systems envisioned in the alternatives because those programs are either conceptual in nature or in the early stages of development. Consequently, 

they entail a greater risk of cost and schedule overruns 

than do programs that are better defined and based on 

proven technologies. CBO’s cost estimates represent one 

possible outcome, calculated under specific assumptions.

Without established DoD requirements as a guide, CBO 

based its estimates of procurement quantities for each alternative on the current force structure and forcestructure plans wherever possible. Procurement quantities 

were not adjusted to try to achieve equivalent capabilities. 

(For example, the 40 operational CAVs purchased under 

each CAV alternative would be equivalent to the payloads 

of only about two long-range bombers.) Details of CBO’s 

methods for developing its cost estimates are described in 

the appendix.

In general, the alternatives that involve penetrating 

bombers—Alternatives 2, 3, 4, and 5—are much more 

expensive to develop and procure, but they offer the advantage of being able to repeatedly deliver relatively inexpensive munitions. The very short response times of the 

CAV alternatives come with the disadvantage of high unit 

costs, which could limit the number procured.

Arsenal Aircraft. The arsenal-aircraft alternative would be 

less costly than the penetrating-bomber alternatives and 

less costly than the CAVs on a per-missile basis, although 

as noted earlier, the arsenal aircraft would have several 

drawbacks. It would, however, represent a new type of 

strike system not comparable with any of today’s systems. 

The lower cost shown in Summary Table 2 assumes that 

aircraft could be drawn from the Air Force’s planned inventory of 180 C-17s purchased for strategic airlift. If 

purchases of more C-17s dedicated only to strike missions were necessary, the cost of this alternative would be 

higher. For example, 15 new aircraft would cost an additional $3.3 billion, CBO estimates. Such additional aircraft would be able to augment the airlift fleet when not 

needed as strike aircraft.

Medium-Range Bombers. The costs for the mediumrange bombers in Alternatives 2 and 3 are based on purchasing 275 of those aircraft, a number similar to the current inventory of F-117 and F-15E strike fighters that a 

medium-range bomber might augment or replace.6

 Replacing those strike fighters with medium-range bombers 

would represent an improvement in strike capability because the new aircraft would have longer range, and all of 

them would be stealthy. (Only the 55 F-117s are stealthy 

today.) Although the current F-117s and F-15Es are aging, that force is not as old as today’s long-range bombers. 

Because the aircraft in Alternatives 2 and 3 would have 

limited ability to conduct global-range strikes, they 

would leave unaddressed the issue of replacing today’s 

long-range bombers. Thus, DoD might have to consider 

developing a new long-range bomber at some other time, 

or it could consider ceding the global-range mission to 

the lower-cost CAV alternatives.

Long-Range Bombers. The costs for the long-range 

bombers associated with Alternatives 4 and 5 are based 

on purchasing 150 of those aircraft, a number similar to 

the current long-range bomber force, and they could be 

used to either augment or replace those aircraft. Those 

new bombers, when coupled with the improved range expected for the Joint Strike Fighter over the F-16s that aircraft is expected to replace, could reduce the need for a 

direct replacement for the F-117 and F-15E forces. Alternatives 4 and 5 would maintain a manned global-strike 

capability, although CAVs might still be desired because 

of their much shorter response times.

Hypersonic CAVs. The alternatives associated with hypersonic CAVs that were examined by CBO would have significantly lower costs than those for the penetratingbomber alternatives. CAVs have the disadvantages, however, of being less flexible than aircraft and very costly to 

purchase in more than limited numbers. CBO estimates, 

for example, that it would cost over $200 billion to purchase enough space-based CAVs to provide the same 

number of weapons as one day’s delivery of 2,000-pound 

6. The F-117 and F-15E are the longer-range tactical strike aircraft 

in the Air Force. The bulk of the force is made up of shorter-range 

F-16 multirole fighters.
SUMMARY XVII

JDAMs by 100 supersonic cruise bombers flying missions 

against targets 7,000 nm from their base. CBO sized its 

CAV alternatives on the basis of the availability of Peacekeeper ICBM boosters to launch them. Of course, larger 

numbers could be purchased, although at a higher unit 

cost because new boosters would have to be designed and 

built. Because the procurement quantities of space-based 

CAVs or ballistic missiles armed with CAVs would probably be limited by their high unit costs, those missiles 

would be unable to fully replace aircraft in the role of sustained long-range strike operations.

CHAPTER

1

The United States’ Long-Range

Strike Capabilities Chapter 1: The United States’ Long-Range Strike Capabilities

The U.S. military possesses considerable capability 

to attack targets anywhere in the world with conventional 

weapons. Shorter-range Air Force and Navy tactical aircraft, forward deployed and supported by airborne tankers, can attack targets in the region where their bases or 

aircraft carriers are located, and Tomahawk cruise missiles 

launched from submarines or surface ships offer a similar 

regional capability. If nearby air bases or aircraft carriers 

are not available, global reach can be achieved with the 

Air Force’s smaller fleet of long-range bombers supported 

by airborne tankers.1

 Tactical ground-attack aircraft were 

used very effectively in Operation Desert Storm in 1991, 

where approximately 900 U.S. strike fighters based in the 

Persian Gulf region or on aircraft carriers nearby flew 

more than 40,000 ground-attack sorties against targets in 

Iraq during the 43-day air campaign. Bomber contributions, although important, were limited because only

B-52 aircraft were available to deliver conventional munitions at that time. (Of the other two bomber types in today’s inventory, the B-1 was not used, and the B-2 was 

not yet operational.)

Despite the effectiveness of the Desert Storm air campaign, planners saw a potential vulnerability in its execution. The heavy reliance on shorter-range tactical aircraft 

suggested that U.S. airpower could be severely limited if 

local air bases were unavailable. That scenario could occur if nations in a region were reluctant to host U.S. military forces, if operations had to take place in an undeveloped area that lacked such bases (or proximity to the sea 

for aircraft carriers), or if an adversary was able to attack 

bases hosting U.S. aircraft with ballistic or cruise missiles. 

Some planners argued that enlarging long-range strike 

forces would mitigate that vulnerability because such systems could be based farther away without an overreliance 

on aerial refueling. Having a greater number of longrange strike aircraft also would increase the number of 

airfields where strike aircraft could be based, and those 

bases could be beyond the range of an adversary’s missiles.

A decade later, the experiences in Operation Enduring 

Freedom (Afghanistan) and Iraqi Freedom confirmed the 

value of long-range strike systems that are less dependent 

on having access to air bases close to the conflict. In the 

case of Afghanistan, basing and airspace restrictions 

forced strike aircraft to fly very long missions with extensive airborne tanker support. (Fighters typically had to refuel several times during a mission.) Against Iraq, strike 

fighters operating from air bases in Kuwait were within 

range of Iraqi cruise and ballistic missiles. Although both 

air campaigns were ultimately successful, those adverse 

circumstances might have posed serious problems, especially if air operations of greater size or length had been 

needed. In contrast, long-range bombers operating from 

Diego Garcia, an island in the Indian Ocean, contributed 

to those campaigns at long ranges from a secure base and 

with less reliance on airborne tanker support.2 Navy aircraft operating from aircraft carriers also contributed to a 

greater relative extent than they did in Desert Storm.

Although the Department of Defense (DoD) is pursuing 

numerous programs to improve its strike capabilities, 

most are focused on modernizing the shorter-range strike 

fighter force or developing more capable munitions.

Notable among those efforts are the F/A-18E/F and Joint 

Strike Fighter aircraft, which are scheduled to replace 

most Air Force, Navy, and Marine Corps strike fighters 

over the next 20 years or so. Although those fighter pro1. Intercontinental ballistic missiles also offer global reach but currently only for nuclear warheads.

2. Bombers were usually refueled in flight as well but not as frequently.
2 ALTERNATIVES FOR LONG-RANGE GROUND-ATTACK SYSTEMS

grams have been in existence for more than a decade, attention is now being given to improving long-range strike 

capabilities. Beginning in the 1990s, the existing bomber 

fleet was progressively upgraded so that it could deliver 

most types of conventional weapons, and the bombers 

were also equipped with the communications gear necessary to take part in tactical ground-attack operations. 

Those types of upgrades continue today. Until recently, 

however, there were no firm plans to expand the bomber 

force or to develop alternative means for conducting conventional strike missions over extended ranges. The Air 

Force has recently begun to examine a variety of strike alternatives with longer range than tactical fighters have, 

including a new medium-range bomber and intercontinental ballistic missiles (ICBMs) armed with conventional warheads. Additionally, the 2006 Quadrennial Defense Review (QDR) report states that DoD intends to 

develop a new long-range strike capability based on land 

and to deploy an initial capability to deliver conventional 

warheads with ballistic missiles fired from Trident submarines.

This Congressional Budget Office (CBO) study looks at 

the potential operational effectiveness and costs of alternatives for improving strike capabilities at combat ranges 

longer than about 1,500 nautical miles (nm) without refueling—ranges that are greater than those of current or 

planned strike fighters carrying typical weapon loads.3

The study considers a spectrum of systems including aircraft, air- and surface-launched missiles, and space-based 

weapons. It compares the capabilities offered by such systems with one another as well as to existing means of providing the same military capability. The alternatives CBO 

examined reflect general classes of weapon systems, not 

specific systems proposed by DoD or by industry. They 

are not intended to identify a preferred solution but 

rather to offer a comparison of the capabilities and costs 

that can be expected from different types of long-range 

strike systems.

The Current Long-Range Strike Force

Today’s conventional long-range strike capability is provided by the Air Force’s fleet of long-range bombers. The 

origins of the current bomber force go back to World 

War II, when large fleets of heavy and medium bombers 

were built to attack the industrial infrastructure of Germany and Japan and interdict surface forces and supplies 

moving to the combat zones. Shorter-range fighters were 

usually used to counter enemy fighters or to provide close 

air support to ground units.4

 Later, as part of the U.S. 

nuclear deterrent during the Cold War, bombers were designed with the long ranges and heavy payloads needed to 

carry large nuclear weapons from bases in the continental 

United States to targets deep within the Soviet Union. Although many strike fighters could also carry nuclear 

bombs, they were primarily designed for conventional 

warfare. Fighter-like aircraft were preferred for conventional missions because accurately delivering unguided 

conventional munitions against heavily defended tactical 

targets required low-altitude operations and fighter-like 

speed and agility. In that case, long range was less important because the fighters were expected to operate from 

bases in Western Europe, close to any fighting in a conventional war between the North Atlantic Treaty Organization and the Warsaw Pact.

At the height of the Cold War, the size of the U.S. 

bomber fleet was significantly larger than it is today. In 

1963, there were 709 B-52s as well as more than 1,000 

other bombers such as the B-47 and B-58. In addition to 

their long-range bombers, the Air Force and Navy had

intermediate-range bombers—with payloads and range 

less than those of the heavy bombers—but by the early 

1990s, the Air Force had retired its F-111s and the Navy 

had retired its A-6 Intruders.5 Today, the bomber force 

numbers 182 aircraft, of which 96 are combat-ready (see 

Table 1-1 for a description of the quantities and capabili3. Unless it is specified otherwise, an aircraft’s range in this study 

refers to its combat radius with a full payload. The combat radius 

is defined here as the distance that an aircraft could fly from its 

base to attack a target and still have enough fuel to return without 

aerial refueling. The total distance the aircraft would fly on such a 

mission would be twice that range. Missile ranges are simply the 

maximum distance from the launch location to the target.

4. Although optimized for their given missions, heavy bombers, 

medium bombers, and fighter bombers could be used interchangeably if circumstances required and conditions permitted. 

For example, Navy fighter bombers were occasionally used to 

attack industrial targets on Japan’s main islands, and the U.S. 

Eighth Air Force used heavy bombers to support the D-Day

landings.

5. In terms of distance from the United States, short-range aircraftcarrier-based Navy strike fighters could be thought of as providing 

a long-range capability. Targets would still need to be relatively 

close to the sea, however.
CHAPTER ONE THE UNITED STATES’ LONG-RANGE STRIKE CAPABILITIES 3

Table 1-1.

Characteristics of Current U.S. Long-Range Bombers

Source: Congressional Budget Office based on Air Force briefings and data from the Congressional Research Service.

Note: JDAMs = Joint Direct Attack Munitions.

a. Measured on an unrefueled basis with a full combat payload.

b. The B-52 can deliver up to 65,000 pounds of payload when armed with conventional air-launched cruise missiles.

c. The number of JDAMs that the B-52 can carry is limited by the number of weapon stations that are able to provide target coordinates to 

the weapon before it is dropped.

d. The B-1 is capable of dashing at speeds up to about Mach 1.2 for limited distances.

e. Features designed to reduce the ability of defensive systems to detect or track the aircraft.

ties of aircraft in the current inventory).6 The three types 

of bombers have significantly different characteristics that 

reflect the evolution of mission tactics and aeronautical 

technologies spanning the nearly four decades over which 

they were developed and fielded.

B-52H Stratofortress

The B-52 is the Air Force’s oldest bomber. Between 1952 

and 1962, the Boeing Company built 744 B-52s of various models. The “H” model in the current fleet first flew 

in 1961 and has more powerful engines, greater payload, 

and longer range than do earlier models. Today’s fleet of 

94 aircraft includes 44 that are combat-ready for both nuclear and conventional missions. B-52s are based at 

Barksdale Air Force Base in Louisiana and Minot Air 

Force Base in North Dakota.

Previous Air Force plans projected that B-52s would remain in the Air Force inventory until 2037, although the 

recently released 2006 QDR report states DoD’s intention to reduce the B-52 inventory to 56 aircraft. Plans remain in place for maintaining and upgrading the smaller 

force. Planned upgrades to the B-52 include improvements to navigation systems, onboard computers, electronic countermeasures, and communications links. The 

Air Force has also considered replacing the engines with 

ones that have lower operating costs, although there are 

no current plans to do so. Continuing to operate the B52s for another two to three decades could present problems with airframe life. Concerns have been voiced about 

Bomber Inventory

Total active 67 21 94

Combat-ready 36 16 44

Average Age (Years) 17 11 43

Combat Radiusa (Nautical miles) 1,800 2,000 3,000

Weight (Pounds)

Empty 190,000 154,000 185,000

Maximum takeoff 477,000 337,000 488,000

Maximum Dropped Payload (Pounds) 54,000 34,000 Usually 50,000 b

Number of 2,000-Pound JDAMs 24 16 12 c

Crew 4 2 5

Employment Speed (Mach) 0.85 d 0.78 0.8

Stealth Features e Some Yes No

B-1B B-2A B-52H

6. Aircraft might not be combat-ready for several reasons. For example, aircraft undergoing scheduled maintenance at a depot are not 

considered combat-ready. Similarly, the level of funding allocated 

for operating a type of aircraft also determines the number that 

can be kept combat-ready.
4 ALTERNATIVES FOR LONG-RANGE GROUND-ATTACK SYSTEMS

corrosion in the airframe and the fatigue life of the upper 

wing surface. As of May 2003, the average age of B-52s in 

the force measured in flight hours was around 15,860 

hours, with the oldest having about 20,700 hours. DoD’s 

Future Years Defense Program (FYDP) for fiscal years 

2006 to 2011 includes about $1 billion for B-52 upgrades over that period. (That total does not include 

funds included to develop electronic warfare pods to enable using B-52s as standoff jammers against enemy air 

defenses. Those plans were dropped in the fiscal year 

2007 budget request.)

The B-52 can carry more types of weapons than the B-1 

or B-2 can—more than 20 different types of conventional and nuclear bombs and missiles from the current 

Air Force inventory. Weapons can be carried in the internal weapons bay or externally under the wings. Planned 

payload improvements include the installation of a laser 

targeting pod and the ability to carry new precision weapons as they are introduced into service. Although the airframe design does not incorporate stealth characteristics, 

the B-52 can attack targets with long-range cruise missiles, such as the Conventional Air-Launched Cruise Missile (CALCM), that enable it to remain beyond the reach 

of air defenses.

B-1B Lancer

After a controversial development history that included 

the cancellation of the –A model by the Carter Administration, the first B-1B bomber entered service in 1986. 

Rockwell International (now Boeing) produced a total of 

100 aircraft by 1988. The current fleet size is 67 aircraft, 

with 36 that are combat-ready and configured for nonnuclear missions. The B-1 no longer has a nuclear mission. B-1s are currently based at Dyess Air Force Base in 

Texas and Ellsworth Air Force Base in South Dakota. 

The Air Force’s plans for the B-1, like those for the B-52, 

call for maintaining and upgrading the force until at least 

2025. Upgrades include installation of improved defensive electronic countermeasures for better survivability 

and an improved computer system that would allow the 

aircraft to carry more types of precision weapons. In addition, the Air Force is improving communications links on 

the B-1B with the B-One Next Enhancement program, 

which seeks to integrate the Link-16 communications 

suite for jam-resistant communications as well as other 

equipment for beyond line-of-sight satellite communications. The 2006 FYDP included about $1.1 billion for

B-1B upgrades over the 2006-2011 period.

The B-1 carries all its munitions in three internal weapons bays. The three-bay configuration gives the bomber 

the flexibility to carry a different type of munition in 

each. While the B-52 has a larger maximum payload in 

terms of weight, the B-1 can carry a greater number of 

most munition types (see Table 1-2). Although not considered to be a stealthy aircraft, the B-1 design incorporates features that give it a considerably lower radar signature than that of the B-52. In addition, the B-1 is the 

fastest of today’s bombers and, with its afterburning engines, can dash at supersonic speeds for limited distances.

B-2A Spirit

The B-2 is the newest aircraft in the bomber fleet. Built 

by Northrop Grumman, the B-2 flew for the first time in 

1989 and was declared operational in 1993. Only 21 aircraft were produced. The current fleet of 21 aircraft includes 16 that are combat-ready and are configured for 

both nuclear and conventional missions. The entire fleet 

is based at Whiteman Air Force Base in Missouri.

DoD also plans to maintain and upgrade the B-2 fleet 

until at least 2025. Planned improvements include 

changes to the radar, integration of new munitions, and 

changes to some of the stealth features to make the aircraft easier to maintain. DoD included about $1.9 billion 

for B-2 upgrades in its 2006-2011 FYDP.

Although the B-1 has some characteristics that reduce the 

ability of radars to detect and track it, the B-2 was designed around stealth to enable missions that could penetrate heavy Soviet air defenses. The primary focus on 

stealth came at the expense of other design attributes such 

as speed, payload, and maintainability. The B-2 is the 

smallest and slowest of today’s Air Force bombers, and 

the need to maintain its radar-evading characteristics 

makes it difficult to deploy to forward bases unless special 

shelters are available. During Operation Enduring Freedom, B-2s flew missions to Afghanistan from the United 

States. Those missions required several aerial refuelings 

plus a brief stop at Diego Garcia to change crews. During 

Operation Iraqi Freedom, B-2s were based in special shelters on Diego Garcia to allow much-reduced mission 

times for the aircraft and their crews. 

Capabilities for Future Long-Range 

Strike Systems

Although they are now used in conventional roles, today’s 

bombers were originally designed to carry nuclear weap-
CHAPTER ONE THE UNITED STATES’ LONG-RANGE STRIKE CAPABILITIES 5

Table 1-2.

Maximum Number of Weapons Carried on Current U.S. Long-Range Bombers

Source: Congressional Budget Office based on data from the Air Force.

ons from bases in the United States to targets deep in the 

Soviet Union. They had to be large to achieve the long 

ranges and carry the large payloads necessary for that mission. For example, the distance from the B-52 base at 

Minot, North Dakota, to Moscow is more than 4,000 

nm, a much longer distance than what would be anticipated for regional conflicts, and a cruise missile armed 

with a nuclear warhead weighs about 3,500 pounds, significantly more than the 2,000 pounds of a GBU-31 

Joint Direct Attack Munition (JDAM), one of the heavier 

conventional munitions that is used in large numbers. 

The nuclear mission was also characterized by deliberate 

planning, operations from a well-equipped home base, 

and the need for only a few (or perhaps just one) nuclear 

attack sorties per aircraft.

For a new conventional long-range strike system, DoD 

could select an aircraft design with range and payload 

similar to those of today’s bombers but with additional 

characteristics—such as ease of deployment to forward 

bases and ease of refueling and rearming for repeated missions—that are desirable in a conventional strike system. 

Large aircraft, however, have the disadvantage of high development, procurement, and operations costs. 

Today’s nonnuclear strike capability, measured in terms of 

JDAM-equivalent payload delivered per day without 

aerial refueling (which captures range, payload, and the 

number of sorties achievable per day), is heavily weighted 

toward fighters with much shorter ranges than those of 

heavy bombers (see Figure 1-1). Depending on the combination of weapons and external fuel tanks carried, typical combat radii for U.S. strike fighters range from less 

than 350 nm to about 900 nm. Consequently, the bulk 

of U.S. strike capability is in that range. The figure shows 

that the delivery capacity of bombers at long ranges is 

about a quarter of the total delivery capacity of the Air 

Force at strike-fighter ranges.7

 Although the long range of 

heavy bombers is necessary for global missions such as 

those flown from the continental United States, a strike 

system with an intermediate range—greater than fighters’ 

but less than heavy bombers’—might provide a less costly 

yet still very capable force. Other approaches might instead develop long-range missiles that could be launched 

from the ground or from ships or submarines.

Prior to the QDR, the Air Force had proposed a threephase approach for improving long-range strike capabilities. For the near term, roughly from 2005 to 2015, that 

proposal called for continuing bomber upgrades such as 

those described above. For the mid-term, roughly from 

2015 to 2020, the proposal called for fielding an interim 

system that, to the extent possible, used current technologies and avoided the risks of substantial development of 

advanced technology. The third phase called for fielding a 

highly advanced capability in about 2035 and beyond. 

Weapon

Mk 82 Unguided 500-Pound Bomb 84 80 45

Mk 84 Unguided 2,000-Pound Bomb 24 16 18

CBU-87/97 Unguided Cluster Bomb 30 34 24

Wind-Corrected Munitions Dispenser 30 0 16

2,000-Pound Joint Direct Attack Munition 24 16 12

Joint Air-to-Surface Standoff Weapon 24 16 12

EGBU-28 Bunker Buster 0 8 0

B-1B B-2A B-52H

7. Aerial refueling increases the useful range of both fighters and 

bombers, although delivery capacity within a given period of time 

still drops with increasing mission distances because each mission 

takes more time.
6 ALTERNATIVES FOR LONG-RANGE GROUND-ATTACK SYSTEMS

Figure 1-1.

Potential Firepower of Current

Air Force Strike Aircraft, Without 

Aerial Refueling

(Number of 2,000-pound JDAM-equivalents per day)

Source: Congressional Budget Office.

Notes: This figure is based on the Air Force’s total inventory of aircraft. Numbers for operational aircraft would be lower.

JDAM = Joint Direct Attack Munition.

The QDR confirmed the need for continuing upgrades 

to existing bombers (Phase 1 of the Air Force plan) and 

called for fielding a new land-based long-range strike capability by 2018 (Phase 2 of the Air Force Plan) but did 

not describe that new capability as an “interim” one, leaving unaddressed the status of the third phase of the Air 

Force’s proposal. 

The general capabilities that the Air Force has proposed 

for future long-range strike systems include:

B Long Range: the ability to attack targets anywhere on 

Earth.

B Responsiveness: the ability to rapidly attack targets at 

any time under any conditions. Desired response 

times range from hours to minutes.

B Flexibility: the ability to carry a wide variety of munition types and to easily incorporate new munitions or 

other new technologies.

B Survivability: the ability to evade or defeat defenses in 

daylight as well as at night.

B Situational Awareness: the ability to use onboard sensors plus connectivity to external information sources 

to improve combat effectiveness.

The Air Force has not identified specific systems to satisfy 

those objectives, although several systems such as a

medium-range-bomber version of the F-22 fighter have 

been informally proposed.

Different performance characteristics can be incorporated 

into a strike system to achieve a given capability. For example, speed can be used to achieve survivability by reducing the amount of time the strike aircraft is within 

range of defenses. Alternatively, reducing the radar cross 

section could increase survivability by decreasing the 

range at which the aircraft would be detected. This study 

compares the capabilities of eight alternatives for future 

long-range strike systems and assesses how basic performance characteristics such as range, payload size and flexibility, signature, and speed contribute to a variety of desired capabilities similar to those identified by the Air 

Force. CBO used those basic performance characteristics 

to calculate design characteristics such as size, fuel load, 

airframe materials, and engine power. In turn, the development and procurement cost of each alternative was 

based on those design characteristics. Chapter 2 provides 

a detailed description of each CBO alternative and an estimate of its cost. Chapter 3 compares how well the alternatives provide the capabilities desired in a new longrange strike system. Details of the cost estimates are in the 

appendix.

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

16,000

18,000

20,000

0 500 1,000 1,500 2,000 2,500 3,000

Fighters and

Bombers

Bombers Only

Nautical Miles to Target
CHAPTER

2

Alternative Designs for Long-Range Strike Systems Chapter 2: Alternative Designs for Long-Range Strike Systems

The Congressional Budget Office considered eight 

alternative systems for conducting long-range strikes that 

span a range of performance and costs. The types of systems CBO analyzed would have performance characteristics (for example, range, speed, and payload) similar to 

systems that have been considered in recent studies prepared for the Department of Defense.1 The next section 

describes the technical analyses that CBO used to estimate the general physical characteristics (for example, size 

and weight) of a system, given a set of desired performance characteristics. The subsequent section describes 

the physical characteristics for the specific systems CBO 

examined. Those physical characteristics, in turn, are necessary to make estimates of the costs to develop and purchase each system. The methods CBO used to develop 

cost estimates are described in the appendix.

The long-range strike alternatives CBO examined included five aircraft-based systems and three missile-based 

systems. The missile-based systems, which would use 

common aero vehicles to carry a warhead to the target, 

would be launched either from the ground on ballistic 

missiles or from satellites placed in advance in low-Earth 

orbit. After reentering the Earth’s atmosphere, the CAVs 

would be able to glide to their target at hypersonic speed.

Technical Considerations for the 

Design of Long-Range Strike Platforms

The purpose of CBO’s analysis is to demonstrate how 

military effectiveness and cost are related to key characteristics of long-range strike systems, particularly their 

range, payload, and speed. Considering both aircraft and 

CAVs, those key characteristics vary widely for the alternatives CBO analyzed. The speed of the alternatives varies from subsonic (for example, a C-17 arsenal aircraft 

that can cruise at about 76 percent of the speed of 

sound—Mach 0.76) to hypersonic (the long-range 

CAVs, which reenter the atmosphere at speeds exceeding 

Mach 20). The payloads carried by the long-range strike 

alternatives vary from 2,000 pounds for an individual 

CAV missile to about 134,000 pounds for the arsenal aircraft. The maximum range at which targets can be attacked varies from global (that is, the 10,000-nauticalmile—or more—range of the space-based CAVs) to 

1,500 nm for the medium-range bombers and arsenal aircraft.2

 In addition, the takeoff and empty weights of the 

aircraft alternatives—which are directly related to their 

range, payload, and speed and are key determinants of 

cost—vary by about a factor of 5 (see Table 2-1).

Whether an aircraft flies at subsonic or supersonic speeds, 

the greater its range and payload, the heavier its weight at 

takeoff will be (to accommodate both the payload and 

needed fuel) and the higher its cost. The speed at which 

an aircraft flies also affects key aspects of its design and 

cost. For example, engines providing sufficient thrust for 

flight at supersonic speeds are generally less fuel-efficient 

and more costly than those designed to propel subsonic 

aircraft. The aerodynamic characteristics of supersonic 

aircraft are also different from subsonic aircraft, which is 

reflected in their differing shapes. Supersonic aircraft tend 

to be longer and narrower than subsonic aircraft in order 

to have an acceptable ratio of lift to drag; a narrow fuselage can, however, constrain the payload an aircraft can 

carry. Supersonic aircraft must also be constructed of materials that can withstand the increased friction-generated 

heat associated with supersonic flight, which also tends to 

1. See, for example, Department of Defense, Defense Planning Guidance: Long Range Global Precision Engagement Study Final Report

(April 2003).

2. Ranges of 3,000 to 4,000 nm are frequently quoted for the C-17 

flying airlift missions. The 1,500-nm mission radius used here 

would correspond to a total unrefueled flight distance of 3,000 

nm.
8 ALTERNATIVES FOR LONG-RANGE GROUND-ATTACK SYSTEMS

Table 2-1.

Long-Range Strike Alternatives Examined by CBO

Source: Congressional Budget Office.

Note: CAV = common aero vehicle; n.a. = not applicable.

a. The ranges shown are the maximum distance from an air base or launcher location to the target. For the aircraft alternatives, the total 

distance flown on an unrefueled mission would be double the values shown.

b. The aircraft’s speed is Mach 0.76; the missile’s speed is Mach 3.0.

c. The bomber’s cruise speed to target is Mach 0.85; it can dash (with a reduction in range) at speeds up to Mach 1.5.

d. The weights shown for space-based CAVs are for an eight-missile satellite. The launch weight includes the space-launch rocket used to 

put the satellite into orbit.

increase their cost. On the other hand, several of the 

long-range subsonic strike aircraft CBO considered were 

assumed to be stealthy (in particular, to be difficult to detect with radar), implying the use of radar-absorbing materials and construction techniques that also increase cost. 

(An aircraft’s shape—for example, a tailless design—can 

also affect its stealth. Because of the associated heat environment, CBO assumed that for supersonic cruise aircraft, shape would be the primary means used to reduce 

radar signature.) 

Range and payload also affect the costs of the CAV systems considered by CBO. A CAV contains a warhead 

made of conventional high explosives encased in a structure designed to be able to maneuver and withstand the 

deceleration and heat generated by atmospheric friction 

as the CAV reenters the atmosphere at high speed and 

glides to its target. Generally, longer-range CAVs must be 

launched on trajectories that have them fly higher above 

the atmosphere, reenter at higher speeds, and experience 

higher deceleration than do shorter-range CAVs.3

 Providing the needed thermal protection and structure to withstand the forces associated with the deceleration affects 

cost. Additionally, costs are greater for the larger booster 

1 Arsenal Aircraft (C-17 with

supersonic missiles) 1,500 0.76/3.0 b 3.4 134,000 277,000 569,509

2 Medium-Range Subsonic

Bomber 1,500 0.85 3.1 20,000 60,000 120,000

3 Medium-Range Supersonic

Dash Bomber 1,500 0.85/1.5 c 3.1 10,000 59,000 126,000

4 Long-Range Subsonic Bomber 2,500 0.85 5.1 40,000 128,000 283,165

5 Long-Range Supersonic

Cruise Bomber 2,500 2.4 1.8 40,000 165,000 439,990

6 Medium-Range SurfaceBased CAV 3,240 14 0.5 2,000 n.a. 48,000

7 Long-Range SurfaceBased CAV Global 20 1.1 4,000 n.a. 193,000

8 Space-Based CAVd Nearly Global 20 1.1 16,000 n.a. 1,584,000

Gross Takeoff

Weight of Aircraft or

Time Required

Full

a Target

to Strike

Launch Weight of CAV

(Nautical miles)a

Full Payload

Range with

(Mach)

Speed

Range (Hours)

at Maximum

(Pounds)

of Aircraft

(Pounds)

Payload

Expended

Unrefueled

(Pounds)

Weight

Empty

3. That general rule applies to the CAVs considered in CBO’s analysis. Conceptual designs exist, however, for long-range CAVs that 

would fly on lower-altitude trajectories. 
CHAPTER TWO ALTERNATIVE DESIGNS FOR LONG-RANGE STRIKE SYSTEMS 9

rockets needed to launch both longer-range CAVs and 

CAV systems with greater payloads (that is, simultaneous 

launch of a larger number of individual CAVs). The 

heaviest and most expensive launchers are those used to 

place multiple CAVs in low-Earth orbit.

The remainder of this chapter discusses in greater detail 

the design considerations incorporated in CBO’s analysis 

of long-range strike alternatives.

Aircraft

CBO’s analysis considers aircraft that could replace existing long-range heavy bombers (the B-52, B-1, and B-2) 

in terms of their range and payload, as well as aircraft that 

could provide improved responsiveness, measured by the 

time required to strike a target at maximum range. Because the Air Force has been discussing the possibility of 

pursuing a medium-range or “regional” bomber potentially derived from the F-22 fighter, CBO also considered 

three medium-range alternatives spanning a wide range 

of potential payloads. Needed range, payload, speed, and 

stealth determine the trade-offs that can be made among 

an aircraft’s aerodynamics, propulsion, and structure. 

Propulsion. All of the new aircraft examined use airbreathing turbine engines for propulsion. Performance of 

the propulsion system is typically measured by specific 

fuel consumption (SFC), which is the pounds of fuel 

consumed per hour per pound of thrust generated. Typical SFC values for jet engines range from 0.5 for an efficient turbofan to 1.0 or greater for high performance, but 

less efficient, supersonic aircraft engines. The lower the 

SFC, the less fuel consumed and the greater the aircraft’s 

potential range or payload. According to CBO’s calculations, aircraft that dash at supersonic speeds can have fuel 

consumption rates up to six or seven times higher than 

rates during subsonic cruise.

Aerodynamics. The shape of the wings and the fuselage of 

an aircraft determine how well it can maneuver through 

the air, as well as how much engine thrust is required to 

overcome the drag caused by the friction of air. One measure of aerodynamic performance is the ratio of the lift 

generated (which must be equal to the aircraft’s weight in 

cruise) to the drag. The higher the lift-to-drag (L/D) ratio, the longer the range of the aircraft for a given speed 

and load of fuel. In addition, low-drag aircraft can cruise 

at higher speeds. Typical values of the L/D ratio for aircraft cruising at optimum speed (the speed that maximizes their range) vary from 10 to more than 20 for subsonic aircraft; ratios of less than 10 are common for 

supersonic aircraft.4

Structures. The ratio of the empty weight of an aircraft—

that is, its weight without fuel, crew, or payload—to its 

maximum takeoff weight indicates its capacity to carry 

fuel and payload. That ratio is called the empty weight 

fraction, which varies from 40 percent to 45 percent for 

bombers and cargo aircraft. The use of modern composite materials in aircraft construction can reduce the 

weight of an aircraft’s structure while preserving needed 

strength. In general, for a given set of engines, the lighter 

the structure of an aircraft, the higher its cruise speed

will be.

The effect that propulsion, aerodynamics, and structures 

have on an aircraft’s range, speed, and payload can be 

quantified by the Breguet range equation, as follows: 5

R = (Vc / SFC)(L/D)ln(Wo / W).

In the equation, R is the aircraft’s range, Vc is the aircraft’s 

cruise speed, SFC is the specific fuel consumption of the 

engines used on the aircraft, L/D is the aircraft’s lift-todrag ratio, Wo is the aircraft’s gross takeoff weight, and W

is the weight of the aircraft minus the fuel burned to 

reach the range R. Thus, the aircraft’s range is determined 

by the performance of its propulsion systems (Vc / SFC), 

its aerodynamics (L/D), and its structure (Wo / W).

6

Starting with a desired payload and assumptions regarding an aircraft’s aerodynamics, propulsion, and structure, 

CBO used a model based on the Breguet range equation 

to estimate the gross takeoff and empty weights for the alternative aircraft displayed in Table 2-1. For the range estimates shown in the table, CBO assumed that the longrange strike aircraft would not be refueled during flight 

4. Work has been done, however, on designs for supersonic aircraft 

incorporating features that could yield cruise lift-to-drag ratios 

approaching 10.

5. See, for example, Daniel P. Raymer, Aircraft Design: A Conceptual 

Approach, 3rd ed., American Institute of Aeronautics and Astronautics Educational Series (Reston, Va.: American Institute of 

Aeronautics and Astronautics, Inc., 1999).

6. For this formulation of the Breguet equation to be used, an aircraft’s flight is divided into a number of phases—such as climb to 

altitude, cruise, and landing—during which SFC, velocity, and L/

D are assumed not to vary (although they can be different for each 

phase). The formulation can also be adjusted to account for payload expended (that is, bombs dropped) during an aircraft’s flight.
10 ALTERNATIVES FOR LONG-RANGE GROUND-ATTACK SYSTEMS

and would cruise until it reached the maximum range 

such that its remaining fuel would be sufficient to enable 

a safe return to its base. At that maximum range, the aircraft would drop its full payload of weapons and return to 

base, preserving about 10 percent of its full fuel load as a 

reserve in case of an emergency. Actual missions would be 

extendable if the aircraft was capable of aerial refueling. 

The total payload carried by an aircraft consists of the 

weapons it expends, any racks or other equipment needed 

to install the weapons in the aircraft, and the aircraft’s 

crew and their equipment.

Other Design Considerations. CBO assumed that its alternatives for long-range strike aircraft would be manned. 

Unmanned versions of such aircraft have been proposed. 

The empty weights and costs of such unmanned aircraft 

might be less than those of the aircraft considered by 

CBO because unmanned aircraft do not need to carry 

crew support equipment. On the other hand, unmanned 

aircraft could require the use of high-bandwidth satellite 

communications for command and control and would 

require the development and testing of complex software 

automating their operation. Those factors would tend to 

increase the cost of unmanned aircraft relative to manned 

aircraft.

Common Aero Vehicles

For the foreseeable future, achieving very fast response 

times (that is, on the order of an hour or less) at global 

ranges will require systems such as CAVs that have trajectories through space. The CAVs CBO examined are reentry vehicles shaped to generate sufficient lift to glide 

many thousands of miles at hypersonic speed as they reenter the Earth’s atmosphere. The CAVs would use a 

combination of thrusters and flaps to maneuver as they 

glide. CBO considered CAVs that could be launched at 

their targets using a surface-based intercontinental ballistic missile (ICBM) or a smaller surface-based mediumrange missile, as well as CAVs that would be placed in 

equatorial low-Earth orbits (at an altitude of 270 nautical 

miles) and de-orbited when needed. Because CAVs have 

the ability to glide and maneuver in the atmosphere, they 

would be more costly and technically challenging than 

simpler reentry vehicles that might only be able to make 

minor course corrections as they reach the target. However, the CAVs’ ability to shape trajectories means they 

could avoid flying over diplomatically sensitive territory 

and could be launched on initial trajectories that would 

preclude spent booster rockets from falling on populated 

areas.7

The Defense Advanced Research Projects Agency was 

conducting a program known as FALCON (Force Application and Launch from the Continental United States) 

to develop the technology to enable CAVs to be built and 

made operational.8 The CAV design that the FALCON 

program was considering would weigh about 2,000 

pounds and carry a payload of 1,000 pounds—either a 

single conventional (that is, nonnuclear) warhead or multiple smaller munitions. The CAVs would be shaped to 

generate sufficient lift at hypersonic speeds to enable 

them to glide long distances downrange (that is, along the 

projection of their ballistic flight path) as well as maneuver to strike targets up to 2,500 to 3,000 nm crossrange 

(the distance perpendicular to their ballistic flight path). 

Their ability to glide and maneuver makes CAVs more 

technologically challenging than the reentry vehicles currently used to carry nuclear warheads, such as the Mark 

12 launched on the Minuteman III ICBM. For example, 

to generate lift, the surface area of a CAV would need to 

be several times as large as that of an existing reentry vehicle—an area that must be protected from the heat generated during the prolonged flight of the CAV at hypersonic speeds. (A CAV would be in flight at hypersonic 

speeds for up to 30 times longer than the times for existing ballistic reentry vehicles. Some observers consider the 

development and testing of materials that could withstand the heat generated for that period of time to be the 

aspect of a CAV program incorporating the greatest technical risk.) The CAV’s speed could give it an advantage

7. The Navy is exploring simpler maneuvering reentry vehicles with 

its Enhanced Effectiveness Initiative for Trident II ballistic missiles. See Congressional Research Service, Conventional Warheads 

for Long-Range Ballistic Missiles: Background and Issues for Congress

(January 2006).

8. Although the FALCON program still exists, its focus has shifted 

from developing an operational weapon to more generic research 

into hypersonic flight. In this study, CBO used “common aero 

vehicle” as a generic term for such weapons because it is the most 

commonly known. The CAV is, however, a specific concept of the 

Air Force’s and the Defense Advanced Research Projects Agency’s. 

The Hypersonic Glide Vehicle is a related concept of the Army’s.
CHAPTER TWO ALTERNATIVE DESIGNS FOR LONG-RANGE STRIKE SYSTEMS 11

over aircraft-delivered conventional munitions if it was 

used against hardened or deeply buried targets.9

The period spanning the time between the launch of a 

surface-based CAV and its arrival at a target comprises a 

number of phases. Those phases include the period during which the CAV is riding on its rocket launcher under 

thrust, the ballistic suborbital flight through space that 

occurs after the CAV separates from its launcher and lasts 

until the CAV reenters the atmosphere, and the period of 

hypersonic glide and maneuver through the atmosphere 

to a target. For long-range CAVs, the boost phase would 

last about three to four minutes, the suborbital phase 

would last about 30 minutes, and the glide phase would 

last from a few minutes (if little crossrange flight or additional downrange flight was required) up to 30 minutes. 

For medium-range surface-based CAVs, the boost phase 

would last somewhat more than two minutes, the suborbital phase would last several minutes, and the glide phase 

would be comparable with that of a long-range CAV.

The use of a space-based CAV would involve a set of 

phases having some commonality with surface-based 

CAVs but also with key elements that are different. In 

particular, a space-based CAV could not, in general, be 

fired immediately following a decision to attack a target. 

Because there would probably be a limited number of 

CAVs in orbit, a certain amount of time would elapse before some CAV’s orbit carried it to a position in space 

within range of the target to be attacked. Once a CAV 

satellite was in position, the orbiting CAV would have to 

fire its attached retro-rocket to slow itself to suborbital 

speed and reenter the atmosphere. Finally, after reentry, 

the space-based CAV would glide and maneuver to its 

target in the same way as a surface-launched CAV would. 

CBO determined the number of different orbital locations needed for the space-based CAVs and the size of 

their attached retro-rockets by imposing the requirement 

that the responsiveness of space-based and surfacelaunched long-range CAVs be equal (see Figure 2-1). 

CBO chose a retro-rocket providing a braking speed of 

0.5 kilometers per second, corresponding to a de-orbit 

time of about 15 minutes from a 270-nautical-mile circular orbit.10 Given a 15-minute de-orbit time, five orbital 

locations at the equator would provide the same responsiveness as would a long-range surface-launched CAV, assuming each CAV had the ability to glide and maneuver 

for up to 30 minutes within the atmosphere. (A constellation with more satellites in equatorial low-Earth orbit 

would provide only marginally shorter response times at 

greater cost.) The 2,500-to-3,000-nm crossrange flight 

that the CAVs could achieve would enable them to strike 

targets located in any of the world’s major populated areas 

from an equatorial orbit.

Other choices for retro-rocket braking speeds are possible, with different braking speeds requiring a different 

number of satellites to achieve the chosen response time. 

However, there is no optimum choice of braking speed 

and number of satellites that would minimize the total 

mass (and, therefore, the launch costs) of a CAV satellite 

constellation for a fixed number of CAVs in orbit. A design with lower braking speeds would have lighter satellites because each retro-rocket would be smaller. However, to compensate for the increase in de-orbit time that 

would result from lower braking speeds, a greater number 

of those lighter satellites would be needed in orbit.

The Specific Long-Range Strike

Alternatives CBO Examined

CBO analyzed eight alternative long-range strike systems 

that reflect several types of systems that have been proposed within the defense community:

Alternative 1—Arsenal Aircraft: Supersonic

Missiles on C-17 Aircraft

A number of previous studies on long-range strike systems have examined the concept of an “arsenal aircraft” 

that could be a military cargo plane or commercial transport converted to carry large quantities of munitions.11

That long-range strike aircraft would not be stealthy; so 

to provide it the capability to attack targets in the pres9. However, if the impact speed of a warhead is too great, its structure will be transformed from solid to fluid and it will fail to penetrate the target. Studies have shown that for steel impacts on 

granite and concrete, maximum penetration depths will occur for 

an impact speed of about 4,000 feet per second (or about Mach 

4). See United States Air Force Scientific Advisory Board, Why 

and Whither Hypersonics Research in the U.S. Air Force (December 

2000).

10. CBO chose a 270-nm altitude for the space-based CAVs because 

it is the lowest orbit that is high enough to prevent friction with 

the residual atmosphere that would cause the CAVs’ orbits to 

decay substantially over their expected lifetime in orbit.

11. See, for example, Department of Defense, Defense Planning Guidance: Long Range Global Precision Engagement Study Final Report

(April 2003).
12 ALTERNATIVES FOR LONG-RANGE GROUND-ATTACK SYSTEMS

Figure 2-1.

Response Times of Long-Range Common Aero Vehicles

(Minutes to strike target)

Source: Congressional Budget Office.

Notes: Response time for the space-based common aero vehicle assumes five satellites in equatorial orbit at an altitude of 270 nautical miles 

and with a 0.5 kilometer per second de-orbiting rocket.

Atmospheric gliding and maneuvering time will vary depending on the target’s location.

ence of sophisticated air defenses, CBO assumed that the 

aircraft’s payload would consist of high-speed cruise missiles with a speed of Mach 3 and a range of 500 nm. 

Those high-speed missiles would be able to reach their 

targets in about 20 minutes or less after launch, although 

times on the order of several hours might be needed for 

the aircraft to fly to the missile-launch location. CBO estimated that, consistent with the C-17’s capabilities, the 

arsenal aircraft would cruise at Mach 0.76 and carry a 

payload of 167,000 pounds, about 80 percent of which 

would be expendable munitions.12 CBO’s analysis indicates that the arsenal aircraft would have a combat range 

of 1,500 nautical miles, which would enable it to attack 

targets at a range of 2,000 nm with the addition of the 

supersonic missile’s 500-nm range. 

Alternative 2—Medium-Range Subsonic

Stealth Bomber

As mentioned earlier, the Air Force has recently discussed 

the potential need for a new medium-range bomber. In 

this analysis, CBO examined a subsonic design having a 

combat range of about 1,500 nautical miles without refueling, a payload of 20,000 pounds, and a cruising speed 

of Mach 0.85. That design assumed a crew of two and 

propulsion from two engines derived from existing designs. CBO’s analysis indicates that the aircraft’s empty 

weight would be about 60,000 pounds, with a maximum 

gross takeoff weight of 120,000 pounds. The design was 

assumed to be highly stealthy, providing the capability to 

conduct operations in the presence of sophisticated air 

defenses.

Alternative 3—Medium-Range Stealth Bomber with 

Supersonic Dash

CBO also examined a medium-range bomber that would 

cruise at subsonic speeds but that would have the capability to dash at supersonic speeds, hereafter referred to as 

Surface Based Space Based

0

10

20

30

40

50

60

70

3

33

30

21

15

30

Boost

Orbital Positioning

De-orbit

Ballistic Flight

Atmospheric Gliding and Maneuvering

12. The C-17’s total payload is about 167,000 pounds. CBO assumed 

that racks and dispenser mechanisms for the high-speed cruise 

missiles carried by the aircraft would compose about 20 percent of 

that total.
CHAPTER TWO ALTERNATIVE DESIGNS FOR LONG-RANGE STRIKE SYSTEMS 13

the medium-range supersonic bomber. That aircraft 

would be similar in concept to a medium-range bomber 

derived from the F-22 supersonic stealth fighter, which is 

being considered by the Air Force. The alternative examined by CBO would have a cruising speed of Mach 0.85 

and could dash at speeds up to Mach 1.5 while carrying 

10,000 pounds. If it cruised exclusively at subsonic speed, 

the aircraft’s combat range would be 1,500 nautical miles. 

However, if the aircraft dashed to its target at Mach 1.5 

and then returned at Mach 0.85, its combat range would 

be about 800 nautical miles; flying exclusively at Mach 

1.5, its range would be somewhat less than 600 nautical 

miles. The aircraft would have a crew of two and be powered by two high-thrust engines, probably derivatives of 

the F119-100 engines used on the F-22. CBO’s analysis 

indicates that the aircraft’s empty weight would be about 

59,000 pounds, and maximum gross takeoff weight 

would be about 126,000 pounds. The design was assumed to be highly stealthy.

Alternative 4—Long-Range Subsonic

Stealth Bomber

When examining a design for a new long-range bomber, 

CBO considered what could be viewed conceptually as 

an improved version of the existing B-2. CBO assumed 

that such an aircraft would have a subsonic cruise speed 

of Mach 0.85, could carry 40,000 pounds of payload, 

and would have a combat range, without refueling, of 

2,500 nautical miles (compared with about 2,000 nautical miles for a fully loaded B-2). CBO assumed that, as 

with the current B-2, this long-range strike aircraft would 

have a crew of two but would use two high-performance 

engines derived from current designs instead of the four 

engines used on the B-2. Assuming that the aircraft’s design could incorporate improvements in both aerodynamic performance and engine fuel efficiency relative to 

the B-2, CBO’s analysis indicates that the aircraft’s empty 

weight could be about 128,000 pounds (compared with 

the B-2’s 154,000 pounds) and that its gross takeoff 

weight would be about 283,000 pounds. The design 

would be highly stealthy.

Alternative 5—Long-Range Supersonic

Cruise Bomber

CBO’s analysis includes a bomber that could cruise at 

Mach 2.4 and carry a payload of 40,000 pounds. Assuming a maximum combat range of 2,500 nautical miles, 

CBO’s analysis indicates that such an aircraft would have 

an empty weight of about 165,000 pounds and a gross 

takeoff weight of about 440,000 pounds.13 A supersonic 

bomber that could cruise to its target at Mach 2.4 would 

have responsiveness about 65 percent better than that of 

the long-range subsonic bomber considered by CBO (1.8 

hours to reach a target 2,500 nautical miles away versus 

5.1 hours). The aircraft would have two crew members 

and four (newly developed) engines. CBO assumed that 

the aircraft would be optimized for high-speed flight and 

would therefore have limited ability to loiter at subsonic 

speeds.14 For this design, the aircraft’s shape would be the 

primary means of achieving stealth—implying that the 

aircraft would be less stealthy than those in Alternatives 

2, 3, and 4—because it is unclear to what extent the special materials used to help further reduce aircraft signatures would be robust enough to withstand the high temperatures of sustained supersonic flight.

Alternative 6—Medium-Range Surface-Based

Common Aero Vehicle 

On the basis of information provided by the Army, CBO 

assumed that a 2,000-pound CAV could be launched on 

a solid-fuel booster rocket small enough to be housed on 

a mobile launcher/erector. The booster could launch a 

single CAV on a trajectory with an apogee of about 49 

nautical miles. Under CBO’s assumptions, the CAV 

would be able to glide up to 3,200 nautical miles downrange and would have a maximum crossrange maneuvering capability of somewhat less than 950 nautical miles. 

CBO assumed that a medium-range CAV battery would 

include two missiles (each carrying a single CAV) placed 

13. CBO’s analysis assumed that technology available in the relatively 

near term would be used to build the Mach 2.4 long-range strike 

aircraft. Over the longer term, technology that might emerge from 

continuation of the Defense Advanced Research Project Agency’s 

Quiet Supersonic Program (or related efforts) could make lighterweight designs for long-range supersonic aircraft possible. If 

improvements in engine SFC and aerodynamics consistent with 

that program’s goals were achieved, CBO’s analysis indicates that a 

Mach 2.4 bomber with a 20,000-pound payload and a range of 

2,500 nautical miles would have an empty weight of about 56,000 

pounds. CBO did not consider alternatives for long-range strike 

aircraft that had cruising speeds well above Mach 3 (so-called 

hypersonic aircraft) because it assumed that the required advancements in technology could not be incorporated into an operational aircraft for more than 20 years.

14. There are proposals for variable-cycle supersonic engines with 

improved fuel efficiency at subsonic speeds. The designs for such 

engines introduce complexities in their operation and maintenance, however, and CBO did not assume that they would be 

developed for and used on the supersonic bomber considered in 

this analysis.
14 ALTERNATIVES FOR LONG-RANGE GROUND-ATTACK SYSTEMS

in two canisters carried on a single mobile launcher. Vehicles carrying launch control systems, command-and-control systems, and other support equipment would also be 

included in the CAV battery, which would be transportable by air. CBO assumed that 24 batteries would be purchased, 20 of which would be for operational use and 

four for spares.

Alternative 7—Long-Range Surface-Based Common 

Aero Vehicle 

CBO assumed that long-range surface-launched CAV capability could be provided by 2,000-pound CAVs 

launched on Peacekeeper ICBMs being retired from their 

strategic nuclear mission. Two CAVs could be launched 

on a single Peacekeeper. CBO assumed that two sets of 10 

Peacekeepers would be modified for operational use, with 

each set capable of launching 20 CAVs. One set would be 

placed in silos constructed at Cape Canaveral Air Force 

Station on the East Coast of the United States, and the 

second set would be placed at Vandenberg Air Force Base 

on the West Coast. That basing arrangement would enable targets to be attacked worldwide while precluding 

the impact of a spent Peacekeeper booster within a populated region (if used, the Peacekeepers would burn out 

over the Atlantic or Pacific Oceans). Four additional systems would be built as spares.

Alternative 8—Space-Based Common Aero Vehicle 

CBO also considered an alternative that would base the 

2,000-pound CAV in space. CBO assumed that five sets 

of eight CAVs would be placed in low-Earth orbit, with 

each set housed in a protective satellite providing power, 

thermal control, station-keeping (the ability to maintain 

proper orbital position and orientation), and communications for command and control. (The earlier discussion 

of general design considerations for CAVs provides the 

rationale for CBO’s choices of orbit and number of satellites.) With eight CAVs housed in each of five orbiting 

protective satellites, this alternative would provide 40 operational CAVs, the same number assumed in Alternatives 6 and 7.15 CBO assumed that the CAV satellites 

would have a service life of about 10 years in orbit. Maintaining a space-based CAV capability for 30 years, a period comparable with the typical service life of military 

aircraft such as those considered in Alternatives 1 through 

5, would require that enough CAV satellites be purchased 

to replace each one twice. With the addition of eight 

CAVs (and one protective satellite) as spares, a total of 

128 CAVs would be purchased under Alternative 8.16

As in its analysis of potential designs for space-based interceptors used for missile defense, CBO examined two 

potential weights for the protective satellites: 50 percent 

of the weight of the CAVs to be housed and 20 percent of 

their weight.17 CBO estimates that the total weight of 

each space-based CAV would be about 2,730 pounds: the 

CAV would weigh 2,000 pounds, and the solid fuel deorbit retro-rocket would weigh about 730 pounds. 

Therefore, eight CAVs housed in a heavier protective satellite would weigh about 32,760 pounds, and eight CAVs 

housed in a lighter-weight protective satellite would 

weigh about 26,200 pounds. CBO assumed that eight 

CAVs housed in a heavier protective satellite could be 

launched from Cape Canaveral into a 270-nautical-mile 

circular equatorial orbit using a heavy-payload version of 

the Delta IV Evolved Expendable Launch Vehicle 

(EELV).18 A Delta IV medium-plus launcher should be 

capable of placing eight CAVs housed in a lighter-weight 

protective satellite in orbit.19 CBO’s cost estimates assume the heavier protective satellite and launch on a 

heavy EELV.

15. As mentioned previously, the crossrange maneuver capability of 

2,500-to-3,000 nautical miles assumed by CBO would enable a 

CAV in an equatorial orbit to reach targets in North Korea or at 

higher latitudes. If development of CAVs with that crossrange 

capability proved infeasible, multiple sets of CAVs in multiple 

inclined orbits would be required to provide the ability to attack 

targets worldwide within an hour, substantially increasing costs.

16. The spare satellite would be needed if a launch vehicle failed during launch or if a satellite malfunctioned while in orbit.

17. That analysis is described in Congressional Budget Office, Alternatives for Boost-Phase Missile Defense (July 2004), available at 

www.cbo.gov.

18. See Boeing Corporation, Delta IV Payload Planners Guide (October 2000 and later supplements), available at www.boeing.com/

defense-space/space/delta/docs/DELTA_IV_PPG_2000.PDF.

19. Ibid.
CHAPTER

3

Comparing the Capabilities of the Long-Range Strike 

Alternatives CBO Examined Chapter 3: Comparing the Capabilities of the Long-Range Strike Alternatives CBO Examined

Two likely roles for future long-range strike systems 

will be to provide a new prompt, nonnuclear global strike 

capability and to contribute to the strike capabilities 

available to commanders in regional conflicts, especially 

those that are conducted over long distances because of 

local geography or basing restrictions. The Department 

of Defense, however, has not established future requirements for long-range strike systems with any detail beyond identifying general types of capabilities such as 

those described in the Secretary’s Prompt Global Strike 

Plan and the Air Force’s nascent three-phase plan for such 

systems (see Chapter 3).1 The Long Range Global Precision 

Engagement Study prepared by the Air Force as directed 

by the Fiscal Year 2004 Defense Planning Guidance also 

established some initial structure to guide thinking about 

future long-range strike capabilities. The study defined 

four “capability focus areas” that describe what DoD expects future long-range strike systems to provide:

B Prompt Global Strike—the ability to strike anywhere 

(from very long ranges if necessary) within about 12 

hours, with an emphasis on global access, survivability, 

and speed at the expense of volume of fire.

B Prompt Theater Strike—survivable strike capability 

over theater distances (up to 2,000 nautical miles) 

with a greater emphasis on volume of fire.

B Persistent Area Strike—strike capability for higher volume of fire from shorter ranges, and attacks against 

time-sensitive targets (10 to 15 minutes from an execute order) provided by high speed or long loiter 

times.

B Battle Management, Command, Control, Communications, Computers, and Intelligence, Surveillance and Reconnaissance (BMC4ISR)—a combination of onboard 

sensors and connectivity to external sensors and communications supporting the other three “focus areas.”

To make quantitative comparisons of the military utility 

of different approaches for long-range strike systems, the 

Congressional Budget Office identified several specific 

capabilities that would enable a future system to contribute substantively to both prompt global strike missions 

and to air campaigns in regional conflicts. Those capabilities include:

B Reach—the ability to attack targets regardless of

location.

B Responsiveness—the ability to attack targets quickly.

B Firepower—the ability to sustain attacks over time.

B Payload Flexibility—the ability to deliver different 

types of munitions.

B Survivability—the ability to avoid or defeat air 

defenses.

Those capabilities are related to, although not the same 

as, the Long Range Global Precision Engagement Study’s capability focus areas. CBO did not assess how much of a 

particular capability might be desired or needed but 

rather compared how well the postulated alternatives (as 

well as today’s forces) could provide them. CBO assumed 

its alternatives would be designed to incorporate other attributes that have been identified as necessary for longrange strike, such as the ability to strike day or night and 

in poor weather, as well as connectivity to the networked 

1. Office of the Secretary of Defense, Report to Congress on: Prompt 

Global Strike Plan (June 2005).
16 ALTERNATIVES FOR LONG-RANGE GROUND-ATTACK SYSTEMS

Figure 3-1.

Distribution of Worst-Case Penetration Distances for Countries of the World, 

Measured by Geographic or Operational Limits

(Cumulative percentage of countries)

Source: Congressional Budget Office based on data from the Central Intelligence Agency, World Fact Book (2003), and the Air Force.

Note: Radius of a B-52 bomber is approximately 3,000 nautical miles.

a. Geographic limits are based on a country’s long axis or maximum distance from open ocean.

b. Operational limits are based on geographic limits plus the need for a tanker to stand off 100 nautical miles and a 30 percent range penalty 

to account for threat avoidance.

force (for example, the ability to send and receive targeting information).

Ability to Reach Targets Anywhere on 

Earth

With the exception of Alternative 6—the medium-range 

common aero vehicle—all of CBO’s long-range strike alternatives offer sufficient range or endurance to fly from 

any base or launch location to almost any other point on 

Earth. Long-range CAVs (Alternative 7) and space-based 

CAVs (Alternative 8) could do so unassisted, and the aircraft alternatives could do so with aerial refueling support. Operational restrictions, however, can prevent a system from being able to attack a target that it would 

otherwise be physically able to reach. For example, because vulnerability to air defenses usually prevents airborne tanker operations inside denied or hostile airspace, 

aerial refueling may not be available in all cases where it 

might be needed to allow strike aircraft to attack targets 

deep within a large country’s borders.2

In general, the longer the unrefueled range of a system is, 

the greater its flexibility to attack targets wherever 

needed. To quantify the flexibility offered by increasing 

unrefueled range, CBO estimated what fraction of the 

Less

Than

250

500 750 1,000 1,250 1,500 1,750 2,000 More

Than

2,000

0

20

40

60

80

100

Geographic Limits a

Operational Limits b

Approximate Radius

of an F-16 Fighter

Approximate

Radius of a

B-2 Bomber

Approximate Radius

of a B-1 Bomber

Worst-Case Penetration Distance (Nautical miles)

2. Today’s tanker fleet comprises converted commercial airliners that 

are easily detected by radar, and the task of aerial refueling requires 

the tanker and the receiver to fly a predictable (and easy-to-target) 

profile while fuel is being transferred. Consequently, most refueling is done in secure airspace, although tankers can be sent into 

hostile airspace if the need warrants it. There have been proposals 

to develop stealthy tankers, but the feasibility of achieving a 

stealthy refueling capability is undetermined.
CHAPTER THREE COMPARING THE CAPABILITIES OF THE LONG-RANGE STRIKE ALTERNATIVES CBO EXAMINED 17

Figure 3-2.

Ability of Alternative Strike Systems to 

Attack Targets Deep in Enemy Territory

(Percentage of countries in the world covered)

Source: Congressional Budget Office.

Note: Alternative 1 = Arsenal aircraft

Alternative 2 = Medium-range subsonic bomber

Alternative 3 = Medium-range supersonic dash bomber 

Alternative 4 = Long-range subsonic bomber

Alternative 5 = Long-range supersonic cruise bomber

Alternative 6 = Medium-range surface-based common aero 

vehicle

Alternative 7 = Long-range surface-based common

aero vehicle

Alternative 8 = Space-based common aero vehicle

a. The results for the medium-range common aero vehicle in Alternative 6 assume that the launcher can be located near the target 

country.

world’s countries would be entirely accessible to each 

long-range strike alternative. That entailed comparing an 

alternative’s unrefueled range (in the case of the penetrating-aircraft alternatives) or its missile range (in the case of 

the arsenal-aircraft and the CAV alternatives) with the 

geographic dimensions of each country. To provide full 

coverage, CBO assumed that the necessary penetration 

distance for each country would be the smaller of the 

longest distance between two points within a country’s 

borders or the farthest distance from an ocean (because 

strike aircraft could approach from the sea). By that measure, even shorter-range tactical fighters could reach any 

point in most of the world’s countries (see Figure 3-1). 

For example, an F-16 carrying two 2,000-pound Joint 

Direct Attack Munitions could reach any point within 

about 80 percent of the world’s countries if aerial refueling was available at the target country’s border (and along 

the route to the border, if necessary) and if its route between the tanker and the target was a straight line.3 The 

F-16’s coverage would drop to about 65 percent of all 

countries if additional operational considerations—in 

this example, the need for a tanker to stand off 100 nm 

outside of the adversary’s border and a 30 percent range 

penalty to account for indirect routes to avoid air defenses—are included. (This discussion does not address 

whether the strike system could successfully avoid air defenses. Survivability is examined in a later section.) Today’s heavy bombers offer full coverage, even with the example’s operational constraints (as shown in Figure 3-1).

Most of CBO’s long-range strike alternatives offer complete or nearly complete coverage as well (see Figure 3-2). 

The long-range surface-based CAV and the two longrange-bomber alternatives would fully cover all countries, 

and the two medium-range-bomber alternatives would 

fully cover about 95 percent of all countries. The

medium-range-bomber alternatives would achieve full 

coverage if they were allowed to enter enemy airspace 

from points on the border closer to the target. The spacebased-CAV alternative’s crossrange maneuverability—the 

ability to fly north or south from its equatorial orbit—

would limit its coverage to North or South latitudes less 

than about 60 degrees but allow it to still fully cover 

about 97 percent of the world’s countries. The mediumrange-CAV alternative would offer full coverage if its 

launcher could be positioned close enough to the target 

country—no farther than about 500 nm for worst-case 

geography and the largest countries but as far as 2,000 

nm in most cases. Consequently, medium-range CAVs 

carried on board surface ships or submarines would offer 

good coverage. (CBO did not estimate the costs of putting CAVs aboard ships or submarines.) 

The arsenal aircraft would offer the least coverage among 

CBO’s alternatives. Its 500-nm missile range and the inability of C-17s to penetrate air defenses would limit its 

coverage to around 75 percent of the world’s countries. 

(CBO assumed that the C-17 would operate 100 nm 

from the border but that the missile would fly directly to 

12345678

0

20

40

60

80

100

Alternatives

a

3. The percentages cited are based on a list of countries found in 

Central Intelligence Agency, World Fact Book (2003). They 

include all countries or autonomous areas listed.
18 ALTERNATIVES FOR LONG-RANGE GROUND-ATTACK SYSTEMS

its target.) That percentage would improve if the C-17 

could launch its missiles from a more favorable location 

on the perimeter of the target country or if air defenses 

were suppressed enough to allow the C-17 itself to penetrate the target country’s borders.

This geography-based approach to examining the penetration capability of CBO’s alternatives does not distinguish among nations that are more or less likely to be 

considered potential threats. Those judgments are subjective and change over time. For three nations commonly 

mentioned today as current or possible future adversaries—North Korea, Iran, and China—the CAV and longrange-bomber alternatives would provide total coverage. 

The medium-range bombers could not reach parts of 

China, and the supersonic air-launched missile could not 

reach parts of Iran and China.

Responsiveness

Responsiveness in a long-range strike system is the ability 

to quickly attack a target after the order to do so is given. 

Systems that can execute their attacks in a shorter period 

of time are said to be more responsive than those needing 

more time. 

In its analysis, CBO considered two operational contexts 

for assessing responsiveness:

B Preplanned Missions—those for which the identity of 

the target is known before the mission begins. Preplanned missions typically achieve responsiveness on a 

timescale of hours or days.

B Fleeting Target/Ground Support Missions—those for 

which the specific target is not known before the mission begins, such as missions involving close air support targets identified by ground controllers when the 

aircraft are already overhead. Such missions typically 

aim for responsiveness on the order of a few minutes.

Those two types of responsiveness are examined separately because each would require that strike systems be 

employed differently.

Many strike missions are preplanned and can be prepared 

long in advance of the actual attack or rapidly as a conflict progresses. Examples of preplanned missions that 

were prepared rapidly were seen at the beginning of Operation Iraqi Freedom when the initial air strikes were advanced several hours in an attempt to hit leadership targets that intelligence sources were thought to have 

located. Responsiveness to fleeting targets was illustrated 

later when a B-1B bomber over Iraq was diverted to attack a building where Saddam Hussein was thought to be 

located. The bomber struck the target less than 15 minutes after receiving the order to attack.

The responsiveness needed against a target depends on 

what the target is and what the target is doing. For example, high responsiveness would usually be desired against 

an adversary’s mobile ballistic missile launchers because 

they might launch their missiles at any time and because 

they are difficult to track for long periods of time. The responsiveness desired against an armored unit, on the 

other hand, would depend on what that unit was doing. 

If it was far from friendly forces, responsiveness on the order of hours or even days might be sufficient because the 

unit would pose no immediate threat and would be easy 

to track. (It might not even be deemed worth an attack.) 

If the same unit was about to overrun friendly ground 

forces, however, responsiveness on the order of minutes 

would be needed.

Several steps contribute to the time that elapses between 

when a target is detected and when it is attacked. Those 

steps include time for transmission and processing of data 

from the sensor that detects the target, time for analyzing 

the data and deciding to attack, time for the decision to 

reach the unit that will conduct the attack, and time to 

prepare and execute the mission. Total times can vary 

widely depending on factors such as the political or military situation, the type of target, the volume of data being 

processed, and the type of strike system tasked to perform 

the attack. This analysis focuses on the time that would 

elapse between when a strike order is received by the attacking unit and when weapons hit the target.

Responsiveness in Preplanned Attacks

Responsiveness in preplanned attacks is primarily a function of the speed of the strike system and the distance to 

the target. Thus, higher speeds and the ability to be based 

close to potential targets contribute significantly to a 

strike system’s responsiveness.4

 The benefit of higher 

4. Other contributing factors include the ability to be quickly 

launched after an attack order is received and the ability to rapidly 

plan the mission (or to conduct detailed planning during transit 

to the target). CBO assumed that its alternatives would be 

designed to incorporate those characteristics.
CHAPTER THREE COMPARING THE CAPABILITIES OF THE LONG-RANGE STRIKE ALTERNATIVES CBO EXAMINED 19

Figure 3-3.

Response Times of Alternative Strike Systems for Preplanned Missions

(Hours to strike target)

Source: Congressional Budget Office.

a. The steps in the line for the supersonic cruise bomber result from its need to slow for aerial refueling.

b. Response times for the common aero vehicle alternatives will vary for a given distance to the target, depending on the specific flight

profile needed. The medium-range common aero vehicle has a maximum distance to target of 3,200 nautical miles.

speed, however, depends on the distance to be traveled, 

because over longer distances, a faster system has more 

time to pull ahead of a slower system. To capture that dependence, CBO compared the preplanned mission responsiveness of its long-range strike alternatives over different mission distances (see Figure 3-3).

Over global distances, the CAV alternatives offer by far 

the best response times because they travel at speeds 

many times faster than aircraft do. The response times for 

CAVs are shown as a band because those times do not depend only on the distance between launch point and target. The specific flight times are dependent on the trajectory that must be flown and are therefore influenced by 

other factors such as the amount of glide trajectory relative to ballistic trajectory needed and, in the case of Alternative 8, the locations of the space-based CAVs in orbit at 

the time a launch order is received.5 Shots requiring a 

crossrange trajectory would need the longer times because 

the difference in range off the ballistic trajectory would be 

achieved by CAV maneuvers in the atmosphere. For the 

space-based CAV, those times could vary from about 15 

minutes to one hour depending on the delay needed for 

an orbiting CAV satellite to move into position and the 

amount of maneuvering the CAV would require after it 

reentered the atmosphere. The upper bound of responsiveness for the space-based CAVs could be reduced by 

placing more CAVs in orbit because that would reduce 

the wait for a CAV to reach the correct orbital position. 

Response times could vary from about 30 minutes to one 

hour for the long-range surface-based CAV. The

medium-range CAV could offer faster response times at 

shorter ranges because of its shorter ballistic phase of 

flight. Short response times for the medium-range CAV 

assume that the launcher is within range of the target. 

The response time could be many hours or days if 

0

5

10

15

20

25

0 2,000 4,000 6,000 8,000 10,000

Common Aero Vehicles (Alternatives 6, 7, and 8)b

Arsenal Aircraft

(Alternative 1)

Medium-Range

Bombers and

Long-Range

Subsonic Bomber

(Alternatives 2, 3, and 4)

Long-Range

Supersonic

Cruise Bomber

(Alternative 5)a

5. Although ranges for the CAV options are referred to in terms of 

ground distance between the launcher and the target, CAVs would 

actually fly a much longer distance along their suborbital trajectories. Similarly, the actual distance flown by the space-based CAVs 

would include the vertical distance from orbit.
20 ALTERNATIVES FOR LONG-RANGE GROUND-ATTACK SYSTEMS

Table 3-1.

Flight Time Needed to Reach a Target in Afghanistan

Source: Congressional Budget Office.

Notes: Diego Garcia is a British-held island in the Indian Ocean.

Aerial refueling would be necessary for the notional missions presented in this table.

a. A speed of Mach 0.85 is representative of the aircraft in Alternatives 2, 3, and 4 and today’s bombers or fighters.

b. A speed of Mach 2.4 is representative of the aircraft in Alternative 5.

c. With foreseeable technology, a Mach 2.4 cruise bomber would probably be too large to operate from an aircraft carrier.

launchers must first be moved to a location within range 

of the target.

The response times for the aircraft alternatives are a 

strong function of speed. The three subsonic aircraft alternatives (1, 2, and 4) have similar response times over a 

wide band of ranges because their speeds are about the 

same over most of their flight to the target. The arsenal 

aircraft is slightly less responsive because the C-17 aircraft 

is slower than the penetrating bombers, at Mach 0.76 

versus Mach 0.85, although the supersonic missile would 

fly the final 500 nm of its mission at Mach 3. The response time of Alternative 3 would be similar to that of 

the subsonic-only aircraft because it could dash at speeds 

up to Mach 1.5 only for limited distances. Its range 

would be less than 1,000 nm if it cruised at supersonic 

speeds. The supersonic cruise bomber (Alternative 5) offers a considerably quicker response, although it would 

have to slow for refueling during missions over distances 

longer than its unrefueled radius (a consideration that results in the stair-step shape of the line in Figure 3-3 on 

page 19).6

 The response-time advantage for Alternative 5 

increases with mission distance. Over long regional conflicts—distances of about 1,000 nm to 1,500 nm—the 

response time of the supersonic cruise bomber would be 

one to two hours shorter than the time for the subsonic 

alternatives. For global missions, the response time for Alternative 5 would be about eight hours shorter than the 

time for the subsonic-aircraft alternatives.

None of today’s systems could match the responsiveness 

of the CAV alternatives over long ranges. Only airborne 

aircraft loitering in the area (or, possibly, aircraft on alert 

at a base very close to the target) could do so. Today’s subsonic bombers would provide ranges and response times 

similar to those of CBO’s subsonic-aircraft alternatives if 

they were flying over similar distances. Navy aircraft have 

the potential to offer better response times than those of 

the aircraft alternatives examined by CBO if an aircraft 

carrier was in the area (see Table 3-1). For example, a 

strike aircraft from a carrier in the Indian Ocean could 

have similar responsiveness against a target in Afghanistan 

to that of the Mach 2.4 bomber in Alternative 5 based on 

the island of Diego Garcia. However, arranging tanker 

support for the shorter-range Navy aircraft might not be 

possible on such short timelines. A carrier-based aircraft 

with a range like that of the medium-range-bomber alternatives would not need such support, however. Operating 

from a carrier would have the advantage of obviating permission to use foreign bases but would still require that a 

carrier be in the area.

Responsiveness Against Fleeting Targets

Although the preplanned response times estimated above 

are adequate against many types of targets, they are too 

long for others. Highly time-sensitive targets include 

those that pose an immediate danger to friendly forces or 

Launch Location Type of Base

United States U.S. territory 15.0 6.0

Guam U.S. territory 10.0 4.0

Diego Garcia Territory of an ally 6.0 2.2

Indian Ocean Aircraft carrier 2.5 c

Flying at Mach 2.4b Flying at Mach 0.85a

Time to Target (Hours)

6. The subsonic bombers might also slow to refuel, but the difference in speed would be much smaller.
CHAPTER THREE COMPARING THE CAPABILITIES OF THE LONG-RANGE STRIKE ALTERNATIVES CBO EXAMINED 21

civilians, those that are exposed for only brief periods of 

time, and those on the move if they cannot be reliably 

tracked. Inadequate responsiveness can lead to unsuccessful attacks because:

B The target is able to complete its hostile action before 

the strike is conducted (for example, an enemy unit 

destroys a friendly unit before close air support arrives);

B Unbeknownst to intelligence, surveillance, or reconnaissance (ISR) systems, the target moves before the 

strike is conducted (for example, a terrorist leader 

leaves a safe house before a strike delivers its attack on 

a now-vacated building); or

B The target moves and the strike system cannot locate 

it to complete the attack (for example, a mobile missile launcher is several miles from its anticipated location before the strike arrives).

For time-sensitive targets, the probability of successfully 

attacking decreases as response time increases. In the first 

two examples above, as time passes, the probability that 

the target will either be relevant or present decreases with 

time. In the third example, the target may still be in the 

general area, but the strike system might have to search 

for it because the target’s movement creates uncertainty as 

to where it will be relative to its last known location. 

When there is great uncertainty about the target’s location, the strike system must be able to search the area 

with its own sensors, a potentially time-consuming process that could expose the attacker to air defenses.

The very short response times needed against fleeting targets—the Long Range Global Precision Strike Study set a 

goal of five to 10 minutes from an execute order—can be 

achieved only with very high speeds or with systems that 

are close to the target from the outset.7 Aircraft would almost certainly have to be airborne before receiving the 

mission because the time needed to taxi and take off 

could consume much of the available time. For example, 

during Operation Desert Storm, the Air Force maintained combat air patrols of strike aircraft, usually F15Es, over Iraq in order to rapidly attack mobile SCUD 

missile launchers. Those aircraft could be minutes away if 

a launch or launcher was detected—close enough to find 

and hit it before it could return to hiding. By comparison, aircraft waiting on the ground would have taken at 

least an hour to reach the area—not soon enough to catch 

the launchers that returned to hiding shortly after firing 

their missiles.

In contrast to preplanned missions originating at air 

bases, aircraft-based strike systems can have shorter response times than those for the CAV alternatives when 

they operate from airborne orbits. If air defenses have 

been suppressed, aircraft could be placed in orbits close to 

or over areas where targets might be expected to appear. If 

air defenses have not been suppressed, orbits could be located in the nearest secure airspace. Because the precise 

locations of targets are not known in advance—if they 

were, they would be preplanned targets—planners must 

provide enough orbits so that a strike aircraft is always 

close enough to provide a sufficiently short response time. 

Consequently, a primary disadvantage to loitering orbits 

is the large number of aircraft that might be needed to 

maintain them: aircraft that could be used elsewhere end 

up tasked to perform orbits in the hope that targets will 

reveal themselves.

In general, more effective loitering strike systems will require fewer aircraft to cover a given target area with a desired response time. Both speed and endurance can help 

reduce the number of strike systems needed to provide 

short response times over a target area. Higher speed enables greater area coverage from an orbit, and longer endurance means fewer systems are needed to maintain an 

orbit around the clock.

The arsenal aircraft (Alternative 1) would have a significantly greater area of coverage from a single orbit than 

would the other aircraft alternatives because the supersonic missile could fly up to 500 nm to the target at 

Mach 3, faster than the other aircraft alternatives (see 

Figure 3-4). Area coverage would increase slowly for targets that were more than 500 nm from the arsenal aircraft 

because the C-17 must fly toward the target at Mach 0.76 

before firing the Mach 3 missile. (That causes the sudden 

decrease in the slope of the curve for Alternative 1 in the 

figure.)

The subsonic penetrating-bomber alternatives (2 and 4) 

would have the smallest area of coverage because of their 

low speed, although that coverage would increase if, as 

7. Improvements in ISR systems and communications links to strike 

platforms could also help responsiveness. For that reason, good 

connectivity to the ISR and communications networks is stressed 

as an important attribute for future long-range strike systems.
22 ALTERNATIVES FOR LONG-RANGE GROUND-ATTACK SYSTEMS

Figure 3-4.

Area Covered from Loitering Orbit for 

Different Response Times

(Thousands of square nautical miles)

Source: Congressional Budget Office.

with the arsenal aircraft, they could be armed with highspeed missiles. The medium-range supersonic bomber 

would perform better than the subsonic alternatives, although it would lack the fuel for a Mach 1.5 dash to 

ranges much greater than the supersonic missile could 

cover at Mach 3. The higher-speed long-range supersonic 

bomber (Alternative 5)—not shown in the figure—

would probably not be employed in this type of mission. 

Its design would probably not be suitable for the long periods of efficient low-speed flight needed for a loiter mission. (Its endurance would be similar to that of the aircraft in Alternative 4 in terms of distance flown but much 

shorter in terms of time aloft.)

The picture changes somewhat when endurance is factored into the number of aircraft required to continuously cover a given area (see Figure 3-5). The figure 

shows the number of strike aircraft needed to continuously cover 45,000 square nautical miles (about 25 percent of Afghanistan) with a response time of not longer 

than 10 minutes. Despite having less endurance than 

some of the other alternatives, the large area covered by 

the supersonic missiles enables the arsenal aircraft to provide coverage with fewer orbit locations than the other alternatives could—and thus fewer total aircraft—for orbit 

locations up to 1,000 nm from base.8

 The number of aircraft needed to fill an orbit increases rapidly as the transit 

distance to the orbit approaches the range of the aircraft 

because the time on-station for each aircraft is rapidly 

shortened. Beyond a 1,000-nm transit distance, only the 

long-range subsonic bomber is well short of its maximum 

range (2,500 nm versus 1,500 nm for the other alternatives). Consequently, if orbit locations are farther than 

1,000 nm from a base (or last aerial refueling), long-range 

subsonic bombers can provide 10-minute response times 

with the fewest number of aircraft dedicated to filling the 

orbits. The medium-range bombers require the largest 

number of aircraft because they have neither the highest 

speed nor the longest endurance. The faster mediumrange bomber, in Alternative 3, can provide coverage with 

fewer aircraft than Alternative 2 can because its higher 

dash speed allows it to cover a greater area from each

orbit.9

The preceding analysis assumes that a bomber’s payload is 

fully expended before it returns to base. That would be 

the case if targets were to arise at a rate that would use up 

the bomber’s munitions during its time on-station or if 

the bombers were tasked to strike preplanned targets at 

the end of that time. If it was necessary to bring back unexpended weapons or if weapons were expended before 

the available fuel, loiter times would be shorter.

Although the CAV alternatives could provide full and 

continuous coverage from a single location—a country or 

ship in the region for Alternative 6, the United States for 

Alternative 7, or low-Earth orbit for Alternative 8—their 

responsiveness would be limited by the time required to 

fly their trajectories. At best, that time would be on the 

order of 10 minutes for a medium-range CAV if the warhead required minimal glide and maneuver time in the 

atmosphere—that is, if the launcher was relatively close 

to the target. The space-based CAV would need at least 

0

250

500

750

1,000

1,250

0 5 10 15 20 25 30

Arsenal Aircraft

(Alternative 1)

Medium-Range

Supersonic

Dash Bomber

(Alternative 3)

Medium- and

Long-Range

Subsonic Bombers

(Alternatives 2 and 4)

Response Time (Minutes to strike target)

8. Distances shown in the figure are from a ground base. Coverage 

could also be measured relative to the distance from an aerial refueling orbit. Relative results would be similar.

9. The figure shows Alternative 3 requiring more aircraft than Alternative 2 for orbits greater than about 1,000 nm from a base. That 

occurs because at long ranges, the supersonic dash that gives the 

bomber in Alternative 3 its extra reach would also seriously limit 

orbit time because of the extra fuel consumed during the dash. 

Because orbiting tactics would probably require air superiority, 

tankers might be on hand to mitigate that limitation.
CHAPTER THREE COMPARING THE CAPABILITIES OF THE LONG-RANGE STRIKE ALTERNATIVES CBO EXAMINED 23

Figure 3-5.

Number of Aircraft Needed for 24-Hour Coverage of 25 Percent of 

Afghanistan with a 10-Minute Response Time

Source: Congressional Budget Office.

Note: This figure assumes that an aircraft expends all of its munitions before returning to base. Endurance would be lower (that is, more aircraft would be needed) if an aircraft returned with unused munitions. Endurance would be higher (fewer aircraft would be needed) if 

distance was measured from an airborne tanker rather than from a ground base.

15 minutes to de-orbit, and the surfaced-based CAV 

would need at least 30 minutes to fly from the United 

States. If significant glide time in the atmosphere was 

needed, response times could be as high as half an hour 

for the medium-range CAV alternative or about an hour 

for the other CAV alternatives.

Sustained Firepower

The previous discussion focused on achieving very rapid 

attacks against high-value targets that are likely to be 

present in limited numbers. Long-range strike systems 

can also be important contributors to large-volume attack 

operations such as those seen in major theater wars. They 

can be especially important if the availability of bases near 

the conflict is limited.

A system’s sustained firepower is determined by the 

amount of munitions it can deliver per mission and its 

sortie rate—the number of missions it can fly per day. 

The sortie rate for an aircraft depends on the duration of 

the missions to be flown and on “turn time,” the time 

needed between missions for servicing and rearming. 

CBO assumed that all of the aircraft would be designed 

for quick turn times but that larger and faster aircraft 

would need longer turn times because they carry a larger 

number of munitions and larger fuel loads.

Under the alternatives considered here, CAVs would be 

incapable of providing sustained firepower because they 

would probably be purchased in limited numbers and because each CAV could be used only once. Among the 

other alternatives, the two medium-range bombers offer 

the lowest bomb delivery rate because they have smaller 

payloads than the longer-range alternatives and fly at subsonic speeds (see Figure 3-6). The aircraft in Alternative 3 

can dash for short distances at Mach 1.5 but would probably not fly entire missions at its dash speed. The arsenal 

aircraft and long-range penetrating bombers have payloads higher than those of the medium-range bombers 

0

20

40

60

80

100

120

140

160

180

0 500 1,000 1,500 2,000 2,500

Medium-Range

Supersonic

Dash Bomber

(Alternative 3)

Medium-Range

Subsonic Bomber

(Alternative 2) Arsenal Aircraft

(Alternative 1)

Long-Range

Subsonic Bomber

(Alternative 4)

Nautical Miles Between Base and Orbit Location
24 ALTERNATIVES FOR LONG-RANGE GROUND-ATTACK SYSTEMS

Figure 3-6.

Bomb Delivery Rates for Alternative Strike Aircraft

(Number of 2,000-pound JDAM-equivalents per aircraft per day)

Source: Congressional Budget Office.

Notes: Data are shown out to the unrefueled radius of each type of aircraft when carrying a full bomb load. All alternatives could achieve 

greater ranges with aerial refueling or reduced bomb loads.

JDAM = Joint Direct Attack Munition.

but similar to one another’s when measured in terms of 

equivalent warhead weight.10 As a result, the relative performance of those alternatives depends on mission distance because speed and turn times are the differentiating 

factors. At short ranges, the arsenal aircraft (Alternative 1) 

and the long-range subsonic bomber (Alternative 4) offer 

the highest bomb delivery rates because they have shorter 

turn times than those of the long-range supersonic cruise 

bomber (Alternative 5). The arsenal aircraft is the highest 

at the shortest ranges because a substantial portion of the 

mission is flown by the missile at Mach 3. At ranges 

above about 1,000 nm, the higher payload and aircraft 

speed allow the long-range subsonic bomber to overtake 

the arsenal aircraft. The long-range supersonic cruise 

bomber has a lower bomb delivery rate than that of the 

other two large-payload aircraft because CBO assumed a 

significantly longer turn time (about double) for that 

more advanced aircraft. Longer turn times would be 

likely because Alternative 5 would have four highly advanced engines versus two engines that would be derivatives of proven designs and because the greater rigors of 

sustained supersonic flight would require more careful 

servicing of the aircraft during its time on the ground. 

The higher speed of the bomber in Alternative 5 does result in shorter missions, however, allowing that alternative to overcome the disadvantage of longer ground times 

for longer-range missions. If the turn time for Alternative 

5 were the same as for Alternatives 1 and 4, its delivery 

rate would be the highest at all mission distances—

slightly higher than the arsenal aircraft at 500 nm, with a 

0

20

40

60

80

0 500 1,000 1,500 2,000 2,500

Long-Range

Supersonic Cruise Bomber

(Alternative 5)

Medium-Range

Subsonic Bomber

(Alternative 2)

Arsenal Aircraft

(Alternative 1)

Long-Range

Subsonic Bomber

(Alternative 4)

Medium-Range

Supersonic Dash Bomber

(Alternative 3)

Nautical Miles to Target

Long-Range

Supersonic Cruise Bomber with

Short Turnaround Time

10. With Alternative 1, the supersonic missile, the total payload 

weight of the C-17 is much higher than that of the long-rangebomber alternative, but most of that weight is associated with the 

launch racks, missile canisters, and the missile motor, not with the 

warheads.
CHAPTER THREE COMPARING THE CAPABILITIES OF THE LONG-RANGE STRIKE ALTERNATIVES CBO EXAMINED 25

Table 3-2.

Examples of Target Types for 

Air-to-Ground Missions

Source: Congressional Budget Office.

Note: The terms “hard” and “soft” characterize the extent to 

which a target is vulnerable to a weapon’s effects such as

its blast wave or its metal fragmentation pattern. The terms 

“point” and “area” characterize the spatial extent of a

target.

growing advantage as mission distance increased. (That 

case is shown as the dashed line in Figure 3-6.)

Payload Flexibility

Payload flexibility is a strike system’s ability to deliver munitions with the most appropriate warhead for a given 

mission. The desired warhead is usually dictated by target 

characteristics. In particular, a target’s “hardness” (its level 

of armor or other protection) and size (how easy it is to 

hit) combine to influence the choice of warhead. At the 

highest level, targets are grouped in four ways that match 

up against four types of warhead (see Table 3-2). The target types shown in the table represent generally preferred 

target/weapon combinations. In many cases, a warhead 

other than the preferred one could suffice. For example, 

unitary blast/fragmentation warheads can be effective 

against trucks if the trucks are arrayed close enough together. In other cases, only one type of warhead would be 

effective. For example, only ground-penetrating weapons 

could destroy hardened, deeply buried targets. (Other 

warhead types might be able to damage such facilities by 

attacking exposed features such as doors or ventilation 

entrances.)

The penetrating-aircraft alternatives (2 through 5) would 

offer the greatest payload flexibility among CBO’s longrange strike alternatives because they could be designed to 

carry all (or nearly all) existing or planned air-delivered 

munitions. Different types of warheads could be developed for the supersonic air-launched missile and the 

CAVs, but they would not be easily interchangeable and 

would require assumptions about what distribution of 

warhead types would be needed in the future. After being 

launched into orbit, the space-based CAV warheads could 

not be changed. The development of different versions of 

each missile would also increase the costs of the alternatives. CBO’s cost estimates assume that the CAVs and the 

supersonic air-launched missile would be armed with 

simple unitary warheads. More complicated warheads—

such as submunitions that require dispensing mechanisms or warheads with seekers for greater accuracy—

would be more costly to develop and integrate into the 

missile systems.

Survivability

Survivability, the ability to complete a mission in the face 

of enemy air defenses and—except in the case of expendable systems such as the CAVs—return safely, is an important attribute for long-range strike systems because 

they would most likely be employed on missions lacking 

substantial air-defense suppression support. Those types 

of missions might include short-notice precision strikes 

that must be executed before enemy air defenses can be 

suppressed or missions conducted early in regional conflicts when suppression support might be available but 

when a potentially dangerous air-defense threat could still 

remain. As with responsiveness and firepower, substantially different survivability characteristics exist for CBO’s 

long-range strike alternatives—differences that would influence the circumstances under which they could be employed.

The CAV alternatives would have the highest survivability against current air-defense systems and any new systems that might be expected in the near future. After a 

CAV is launched, its combination of hypersonic speed, 

small size, and maneuverability—which means it does 

not travel a predictable ballistic trajectory—makes it a 

difficult target that only sophisticated ballistic missile defenses, which do not exist today, could defeat. A CAV 

Type Examples Preferred Weapons

Hard Point Deeply buried bunker Unitary penetrators

Hardened aircraft

shelter

Hard Area Dispersed armored

vehicles

Penetrating submunitions 

with target seekers

Guided shaped charge 

weapons

Soft Point Buildings Unitary blast/

fragmentation

Soft Area Supply dumps Unitary blast/

fragmentation

Dispersed trucks Bomblet submunitions
26 ALTERNATIVES FOR LONG-RANGE GROUND-ATTACK SYSTEMS

would be a challenging target even in cases requiring it to 

expend much of its speed to reach targets at the limits of 

its crossrange capability. Directed energy weapons, such 

as lasers, might eventually be able to defeat a CAV, although such technologies are in their infancy, and the 

CAV’s thermal shielding against atmospheric heating 

would make it inherently resistant to such defensive

measures.

Attacking a CAV system before it launches a missile 

would also be difficult. The surface-based CAVs would 

be located in secure areas far from an adversary’s country—in the United States for the long-range CAV and 

perhaps at sea for the medium-range CAV. Consequently, 

attack from the ground would be difficult, and an adversary would need a long-range strike system to attack by 

air. Attacking the orbiting CAVs would require an advanced antisatellite system capable of hitting a target in 

equatorial low-Earth orbit. Although there is concern in 

DoD about the vulnerability of space systems in the future, the existence of antisatellite systems, other than 

those explored by the United States and the Soviet Union 

during the Cold War, has not been confirmed.11

The survivability of the arsenal aircraft would be limited 

by the C-17 launch platform. The missile itself would be 

difficult for air defenses to engage because of its high 

speed, small size, and its potential to be designed to incorporate some stealth characteristics. However, the system’s survivability would be high only if the C-17 could 

remain beyond the reach of enemy air defenses. The C17 is not stealthy and could be detected and tracked by 

radar. Modern surface-to-air missile (SAM) systems, if located on a country’s border, could force the C-17 to remain well outside the enemy’s border, seriously limiting 

the effective reach of the 500-nm supersonic missile. For 

example, the Russian-built SA-20 system is reported to 

have a maximum range of slightly over 100 nm.12 Enemy 

fighters could also be a serious threat because they could 

choose to cross their borders and intercept the C-17s even 

farther out. That threat could only be countered by U.S. 

fighter support if air-superiority fighters were already 

present in the region.

The survivability picture is more complicated for the alternatives that use penetrating stealthy bombers. The very 

low observable characteristics of the medium-range 

bombers and the long-range subsonic bomber (Alternatives 2 through 4) would offer good survivability against 

surface air defenses for operations in darkness and probably also in daylight, although advanced optical systems 

might be able to detect a high-altitude aircraft in daylight 

and cue a SAM intercept. Enemy interceptors at altitudes 

similar to those of the bombers could be a serious daytime threat, however. They could more easily detect the 

bombers, either visually by their crews or with long-range 

cameras, and such detection could occur at ranges short 

enough for air-to-air missiles or cannons to be effective. 

To help counter that threat, the bombers could be armed 

with air-to-air missiles of their own, but their slower 

speed and lack of maneuverability relative to fighters 

would still put them at a disadvantage. Alternative 3 

could have good survivability against that threat because 

the bomber could turn away and try to escape at supersonic speed. Although interceptors might be faster, if the 

bomber began its escape early enough, its greater endurance could allow it to remain out of range long enough 

for the interceptors to exhaust their fuel. The fighters 

would not have destroyed the bomber, but they would 

have prevented it from completing its mission. As with 

the arsenal aircraft, the air-to-air threat would be lower if 

friendly fighters were available to support the bombers. 

Although less stealthy than the other penetrating bombers, the long-range supersonic cruise bomber (Alternative 

5) would have the advantage of even higher speed. That 

speed would shrink the effective range of SAM systems by 

reducing the amount of time available for an engagement. Although the bomber might be detected at a 

greater distance, it could pass beyond the range of the 

SAM before it was overtaken by the missile. Similarly, the 

ability to sustain a speed of Mach 2.4 would make it difficult for airborne interceptors to catch the bomber. That 

could give the aircraft in Alternative 5 better daytime survivability than the slower aircraft alternatives would have.

11. The antisatellite mission against a CAV is made more difficult 

because, except for countries on the equator, the CAV satellite 

does not pass directly over its target. Consequently, more powerful 

booster rockets would be needed to reach a CAV orbit, and a 

ground-based antisatellite laser would, in most cases, not have a 

direct line of sight to the satellites.

12. Duncan Lennox, ed., Jane’s Strategic Weapons Systems, Issue 43 

(July 2005).
CHAPTER

4

Cost and Force-Structure Implications Chapter 4: Cost and Force-Structure Implications

The long-range strike alternatives the Congressional 

Budget Office examined would offer diverse capabilities. 

No single alternative provides superior effectiveness 

across all of the focus areas for long-range strike capability. In addition to simple differences in capability, each alternative would fit into the existing force structure in different ways. For example, fielding common aero vehicles 

would provide a new rapid-strike capability but could not 

replace the firepower offered by today’s bombers when 

those aircraft are retired from service. A supersonic 

bomber, on the other hand, could replace the aged bombers but would offer significantly less improvement in responsiveness than CAVs would. Because of such distinctions, the alternatives CBO examined should not 

necessarily be viewed as mutually exclusive. Depending 

on how the Department of Defense eventually defines its 

requirements for long-range strike capability, a mix of different systems might be needed.

Further complicating comparison of the alternatives are 

the significant differences in the estimated costs to develop and field them (see Table 4-1). Research, development, test, and evaluation (RDT&E) costs could vary by 

over an order of magnitude, CBO estimates, with the 

missile alternatives at the lower end and the advanced supersonic bomber at the upper end. CBO’s estimates of 

production costs vary over a similarly broad range, although the variation results in part from assumptions 

about how many of each type of system would be procured. In the absence of established DoD requirements, 

CBO chose quantities consistent with current forcestructure plans and the procurement of past systems. Details of the methods CBO used to develop its cost estimates (with the exception of assumed procurement quantities) are described in the appendix. This chapter 

describes the assumptions underlying the procurement 

quantities used in the cost estimates and discusses the effect that cost and force-structure considerations, in conjunction with the capabilities described in Chapter 3, 

could have on decisions about which future long-range 

strike systems might be pursued.

Aircraft-Based Systems—Alternatives 1 

Through 5

The alternatives that include new aircraft designs would 

be significantly more costly to develop and procure than 

the alternatives that only develop new missiles, CBO estimates.1

 Aircraft development costs tend to be higher than 

missile development costs because of an aircraft’s much 

greater complexity and size, as well as having to be designed for many years of operation rather than a single, 

one-way mission. Consequently, it is unlikely that DoD 

would simultaneously pursue more than one alternative 

for long-range aircraft. However, combinations of

aircraft-based and missile-based alternatives could provide capabilities that DoD might judge to be costeffective.

Alternative 1: Arsenal Aircraft with 

Supersonic Missiles

Along with the surface-based CAVs, the arsenal-aircraft 

alternative, at just over $4 billion, would be among the 

least expensive of the alternatives CBO examined if DoD 

chose to not purchase additional C-17s as dedicated 

launch platforms. DoD has nearly completed purchasing 

180 C-17s for strategic and tactical airlift missions, and 

some of those aircraft could be used to deliver missiles. 

The 2,000 missiles slated for purchase under Alternative 

1 would be a quantity on a par with the number in other 

tactical missile systems such as the Navy’s Joint Standoff 

1. The difference between the aircraft-based and missile-based alternatives would be even greater if operation and support costs were 

included. CBO focused on acquisition costs for those comparisons because they are sufficient for assessing top-level distinctions 

among the various alternatives.
28 ALTERNATIVES FOR LONG-RANGE GROUND-ATTACK SYSTEMS

Table 4-1.

Estimated Costs of Long-Range Strike Alternatives Examined by CBO

Source: Congressional Budget Office.

Note: RDT&E = research, development, test, and evaluation; CAV = common aero vehicle.

a. The costs for Alternatives 2 to 5 exclude munitions.

b. Includes additional military construction costs of about $1 billion for the aircraft alternatives (2 to 5) and $600 million for Alternative 7.

c. The quantity shown is the number of supersonic missiles purchased. The lower of the two costs assumes that those missiles would be carried by C-17 aircraft in the current fleet. The higher of the two costs assumes that 15 additional C-17s would be purchased to support the 

strike mission.

d. Average unit procurement cost is for supersonic missiles only.

e. Alternative 7 assumes that 24 Peacekeeper missiles would be converted to carry two CAVs per missile. If more missiles were desired, as 

many as 60 Peacekeepers might be available for conversion. The cost of additional missiles would be much higher than the cost shown 

here because new boosters would be needed.

f. Enough satellites would be purchased to maintain the constellation for 30 years. Only 40 space-based CAVs would be available for use at 

any one time.

Weapon (JSOW) and the Air Force’s Joint Air-to-Surface 

Standoff Missile (JASSM).

If DoD decided that aircraft dedicated to the strike mission were needed, procuring 15 additional C-17 aircraft 

would cost about $3.3 billion, CBO estimates. That 

number of aircraft could maintain continuous coverage 

of about 45,000 square nautical miles with a 10-minute 

response time. The estimated cost for those additional 

aircraft would be considerably higher, however, if the decision to purchase them was not made before the C-17 

production line closed. Because the 2006 Quadrennial 

Defense Review did not identify plans to purchase more 

than 180 C-17s, currently planned production will end 

by 2010. Purchasing additional aircraft would have the 

advantage of being able to augment the airlift fleet when 

they are not needed as strike aircraft. Alternatively, C-17s 

from the air-mobility fleet could be pressed into service as 

strikers if the circumstances required, although that 

would decrease the number of C-17s available to move 

cargo.

In many respects, the arsenal aircraft would offer performance similar to that of the long-range subsonic penetrating bomber (Alternative 4), albeit for shorter distances. For example, the two alternatives would have 

1 Arsenal Aircraft 2,000 c 1.5 2.8/6.1 c 4.3/7.6 c 1.4 d

2 Medium-Range Subsonic

Bomber 275 19 52 72 188

3 Medium-Range Supersonic

Dash Bomber 275 23 61 85 220

4 Long-Range Subsonic Bomber 150 31 61 93 409

5 Long-Range Supersonic

Cruise Bomber 150 69 137 207 912

6 Medium-Range SurfaceBased CAV 48 2.4 1.2 3.7 26

7 Long-Range Surface-Based CAVe 24 2.5 0.9 4.0 36

8 Space-Based CAV 128 f 4.0 7.7 11.7 55

RDT&E Procurement

Costsa

Quantity

Average Unit Procurement Cost

Total (Millions of 2006 dollars) b

(Billions of 2006 dollars)
CHAPTER FOUR COST AND FORCE-STRUCTURE IMPLICATIONS 29

similar firepower up to about 2,000 nautical miles and 

would require a similar number of aircraft to maintain responsive strike orbits up to 1,500 nm from a base or 

aerial refueling point. A major disadvantage of Alternative 1, however, would be the aircraft’s lack of stealth, 

which would make it unable to enter hostile airspace until after defenses had been suppressed. For strike missions 

without defense suppression support, Alternative 1 would 

have a penetration depth equal to only its missile’s range, 

about 500 nm—a distance only on the order of that for 

short-range fighters. Penetration of hostile airspace would 

be further limited if enemy fighters were able to fly out 

beyond their borders to intercept the C-17s. Increasing 

the range of the missile could alleviate that shortcoming 

but at higher cost and a smaller carriage capability on the 

aircraft.

To overcome the disadvantages of delivery from a nonstealthy C-17, Alternative 1’s missile could be developed 

in conjunction with a stealthy bomber. The size and 

weight of the notional missile are similar to those of 

GBU-28 bunker-buster bombs that can be delivered by 

B-2 bombers. Any of the aircraft alternatives could be designed to accommodate the supersonic missile, although 

it would be most difficult to fit such bulky weapons into 

the smaller medium-range supersonic dash bomber in Alternative 3. If a long-range bomber (or one of today’s B2s) was to carry it, the supersonic missile would enjoy the 

advantages of stealth, global delivery range, and rapid responsiveness (from an orbiting aircraft) against fleeting 

targets. Integrating the missile onto more than one aircraft would require additional development costs because 

the missile would probably be launched in different ways: 

from a container in an arsenal aircraft, from a rotary 

launcher in a penetrating bomber’s internal weapons bay, 

or from an external weapons station on an F-15E. Responsiveness at global ranges would still lag far behind 

that of the CAV alternatives, however.

Alternatives 2 and 3: Medium-Range Bombers

The medium-range stealth bombers would improve strike 

capabilities over regional distances but would not be as 

well suited for missions with a global range, although 

such missions might be possible with extensive tanker 

support. As a result, medium-range bombers would probably not be a suitable replacement for some of the capabilities offered by today’s long-range heavy bombers. 

CBO assumed instead that DoD would purchase about 

275 of the aircraft as replacements for F-117 stealth fighters and F-15E Strike Eagles.2

 For that number of aircraft, 

a medium-range subsonic bomber force (Alternative 2) 

would cost about $72 billion, and a medium-range supersonic dash bomber force (Alternative 3) would cost about 

$85 billion, CBO estimates. The result would be to provide substantial firepower capability at ranges beyond 

those of today’s strike fighters but no improvement at 

heavy-bomber ranges (see Figure 4-1). That result is illustrated by the additional delivery capability beyond 700 

nm—about a 70 percent increase for Alternative 2 and 

about a 35 percent increase for Alternative 3 for ranges 

up to 1,500 nm. For ranges greater than 1,500 nm, the 

improvement offered by the medium-range bombers 

drops quickly because the aircraft must carry reduced 

bomb loads to fly those distances. In addition to having 

greater range, that entire portion of the force would be 

stealthy. Today, there are only 55 stealthy F-117s that are 

operational compared with 217 conventional F-15Es. 

Depending on the alternative selected, however, the new 

force could lack the air-to-air capability of the dual-role 

F-15E.

The purchase of 275 aircraft under Alternatives 2 and 3 

would increase delivery capability at short ranges relative 

to that of today’s force but by a smaller proportion (as 

shown in Figure 4-1). As an alternative, those notional 

forces could be sized to match today’s short-range capability, although that would result in a lesser improvement 

between 900 nm and 1,500 nm—about 22 percent. Such 

a force would need either 85 medium-range subsonic 

bombers or 170 medium-range supersonic dash bombers. 

For those purchase quantities, the costs of Alternatives 2 

and 3 would drop to about $42 billion and $66 billion, 

respectively, CBO estimates.

Although medium-range bombers alone could not replace all of the capabilities of heavy bombers, a mediumrange bomber force in concert with one of the CAV alternatives would provide a capability that some might argue 

could reduce or eliminate the need for heavy bombers. 

The CAVs would provide prompt strike at global ranges, 

and the medium-range bombers would provide substantial firepower for regional conflicts. Replacing heavy 

2. This approach assumes that the fraction of the inventory that is 

maintained in a combat-ready status is similar for both the current 

aircraft and the aircraft in CBO’s alternatives. Although surface 

CAV missiles would require periodic maintenance, their combatready status could be nearly 100 percent. The space-based CAVs 

would have a 100 percent combat-capable rate unless there were 

irreparable failures while in orbit.
30 ALTERNATIVES FOR LONG-RANGE GROUND-ATTACK SYSTEMS

Figure 4-1.

Potential Firepower of Alternative Air Force Strike Forces, Without

Aerial Refueling

(Number of 2,000-pound JDAM-equivalents per day)

Source: Congressional Budget Office.

Notes: Future forces are assumed to retain current bombers and short-range fighters but to replace today’s F-15Es and F-117As with 275 

medium-range subsonic or supersonic bombers.

This figure is based on the Air Force’s total inventory of aircraft. Numbers for combat-ready aircraft would be lower.

JDAM = Joint Direct Attack Munition.

bombers with CAVs for global missions would have the 

disadvantage of reducing firepower over global ranges. Although missions of long durations over global ranges 

limit the sortie rates of today’s bombers to well below one 

mission per aircraft per day, large long-range bomber 

forces could still deliver a considerable number of bombs 

per day.3

 For example, a B-2 with a payload of 16 Joint 

Direct Attack Munitions could generate an average delivery rate of about three to four JDAM per aircraft per day. 

When multiplied by many bombers in a large force, that 

delivery rate would exceed one that would be practical 

with long-range CAVs. Historically, however, globalrange conventional strikes such as the B-2 missions from 

Missouri to Bosnia have involved only small numbers of 

bombers. That may be because target sets have been small 

or because only stealth aircraft—and hence only a small 

fraction of the bomber force—were suitable for those 

missions.

Alternative 3 is similar to Alternative 2 in terms of range 

and cruise speed. The additional ability to dash at Mach 

1.5 comes with the penalty of having half the payload of 

the medium-range subsonic bomber and an estimated 

cost about 20 percent higher—$85 billion versus $72 billion—for the same production quantity of 275 aircraft. 

As with Alternative 2, this alternative would provide significantly improved strike capability relative to the F-117 

and F-15E fighters that would be replaced.

Alternative 3 would have a sizable advantage—about a 

factor of two for orbits less than 1,000 nm from the last 

refueling base or tanker—over Alternative 2 with respect 

0

5,000

10,000

15,000

20,000

25,000

0 500 1,000 1,500 2,000 2,500 3,000

Nautical Miles to Target

Force with Medium-Range

Subsonic Bombers

(Alternative 2)

Force with Medium-Range

Supersonic Dash Bombers

(Alternative 3)

Current Force

3. Bombers are often deployed to forward locations during sustained 

operations to overcome the limitation of that sortie rate.
CHAPTER FOUR COST AND FORCE-STRUCTURE IMPLICATIONS 31

Figure 4-2.

Total Potential Firepower of Alternative Bomber Forces, by Mission Distance

(Number of 2,000-pound JDAM-equivalents per day)

Source: Congressional Budget Office.

Notes: Data are shown out to the unrefueled radius of each type of aircraft when carrying a full bomb load. All alternatives could achieve 

greater ranges with aerial refueling or reduced bomb loads.

This figure is based on the total number of aircraft purchased. Numbers for combat-ready aircraft would be lower.

The arsenal aircraft (Alternative 1) is not shown because that alternative does not assume a specific quantity of aircraft.

Unlike the display in Figure 4-1, the current bomber force firepower is shown here without daily sortie constraints.

to the number of aircraft needed to maintain very short 

response times against time-critical targets because the 

bomber’s supersonic dash speed would allow it to attack 

targets at greater distances within a given response time. 

However, the lower payload for Alternative 3 could negate that advantage somewhat if the aircraft had to attack 

targets at a rate that would exhaust its munitions well before its fuel. The lower payload would result in significantly lower firepower than that of the subsonic bomber, 

which could deliver munitions at about twice the rate of 

the supersonic dash bomber during sustained operations.

Proponents of an aircraft similar to the supersonic 

bomber in Alternative 3 argue that its superior ability to 

elude enemy fighter aircraft could be an important advantage, especially for daytime strike missions. As was 

discussed in Chapter 3, however, those circumstances 

might be rather narrow, and, if the bomber was confronted by enemy fighters on the way to the target, the 

act of eluding the fighters might prevent it from completing its mission.

Alternatives 4 and 5: Long-Range Bombers

Long-range stealth bombers would improve strike capabilities over global distances. The subsonic bomber (Alternative 4) would require tanker support comparable 

with that of today’s bombers. The supersonic cruise 

bomber (Alternative 5) would require greater tanker support because of its high fuel consumption. CBO assumed 

that DoD would purchase about 150 of the aircraft as replacements for the B-1, B-2, and B-52. Despite the similarity in numbers to the current bomber force, that re0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

0 500 1,000 1,500 2,000 2,500

Long-Range

Supersonic

Cruise Bomber

(Alternative 5)

Medium-Range

Subsonic

Bomber

(Alternative 2)

Current Bomber

Force

Long-Range

Subsonic

Bomber

(Alternative 4)

Medium-Range

Supersonic

Dash Bomber

(Alternative 3)

Nautical Miles to Target
32 ALTERNATIVES FOR LONG-RANGE GROUND-ATTACK SYSTEMS

placement would result in some changes in firepower 

capability (see Figure 4-2). For the long-range subsonic 

bomber in Alternative 4, a smaller inventory (150 under 

CBO’s notional alternative versus 182 bombers currently 

in place) plus a lower payload relative to that of the B-1 

and B-52 would result in less total delivery capability 

than that of the current force. In practice, the difference 

might be smaller than shown in the figure if the Air Force 

could maintain a larger fraction of the new bombers in 

combat-ready status. The actual number of new bombers 

DoD might decide it needs would depend on that consideration as well as assessments of future requirements.

The lower inventory and lower payload of the long-range 

supersonic cruise bomber in Alternative 5 relative to 

those of the B-1 and B-52 would also result in lower firepower at shorter ranges, but the faster bomber’s shorter 

mission time would reduce that difference for longer mission distances. As with the medium-range-bomber alternatives, Alternatives 4 and 5 would result in an all-stealth 

bomber force.4

 Today, there are only 21 stealthy B-2s 

compared with 161 conventional B-1s and B-52s.

CBO’s estimate of Alternative 4’s cost—$93 billion—is 

somewhat higher than the cost for the medium-rangebomber alternatives—$72 billion for Alternative 2 and 

$85 billion for Alternative 3—but only about half the 

number of aircraft would be purchased. Despite its lower 

numbers, Alternative 4 would still outperform the alternatives for medium-range bombers in terms of firepower. 

However, only 25 additional medium-range subsonic 

bombers—for a total of 300—would be needed for Alternative 2 to match the firepower of Alternative 4 at ranges 

up to 1,500 nm. CBO estimates that adding those aircraft would increase the cost of Alternative 2 to about 

$74 billion, a total lower than the total cost for 150 longrange subsonic bombers. In contrast, because of the lower 

payload of the medium-range supersonic dash bombers 

in Alternative 3, about 600 of those would be needed to 

match the firepower of the long-range subsonic bomber 

in Alternative 4. That large force would cost about $131 

billion, CBO estimates.

The long-range supersonic cruise bomber in Alternative 5 

is the most advanced concept examined in this study. 

Whereas the other aircraft could use many technologies 

already developed for existing systems, Alternative 5 

would represent an all-new design. Consequently, it 

would come with a much higher price tag—about $207 

billion to develop and field 150 bombers, CBO estimates. That is more than double the estimated costs for 

Alternatives 3 and 4 and nearly triple the cost of Alternative 2. For its higher price, the long-range supersonic 

cruise bomber would offer capabilities between those of 

subsonic bombers and CAVs. At short mission distances, 

the supersonic bomber in Alternative 5 would offer modest improvements in responsiveness relative to subsonic 

aircraft but with lower sustained munitions delivery rates 

(firepower). At very long ranges, Alternative 5 would offer the greatest firepower but would be far less responsive 

than would the CAV alternatives. Depending on the level 

of stealth that could be incorporated into its high-speed 

design, the bomber in Alternative 5 might have better 

survivability than that of the other aircraft alternatives because its high speed would give both air and ground 

threats little time to engage it. However, CAVs would 

have a better chance of reaching their targets.

The performance and cost of the bomber in Alternative 5 

suggest it would be a preferred system only under a narrow set of requirements—specifically, if large rates of munitions delivery are desired over global distances where 

the bomber’s speed and range combine to give it a substantial firepower advantage over the other alternatives. 

Such situations, however, would probably occur rarely or 

not at all. The rapid delivery of large numbers of munitions is typically associated with conflicts that include 

substantial forces on the ground, which implicitly suggests that some regional access for strike aircraft would be 

available. Aircraft carriers could provide strike capability 

far from the United States against those targets that can 

be reached from the sea until regional bases could be established. Time-sensitive targets, those for which there is 

not time to move a carrier into position or to fly to from 

the United States at subsonic speed, typically do not require a great volume of firepower but rather a few wellplaced bombs. In those cases, the CAV alternatives could 

offer adequate firepower and much better responsiveness 

than the bomber in Alternative 5. Consequently, it could 

be argued that an approach that develops a CAV option 

and a new subsonic bomber would provide more broadly 

useful capabilities at less cost than would a long-range 

supersonic cruise bomber.

4. As was noted in Chapter 3, the supersonic cruise bomber would 

be less stealthy than the other alternatives because it would rely 

only on its shape to achieve its low-observable characteristics. Its 

very high speed, however, would augment its survivability.
CHAPTER FOUR COST AND FORCE-STRUCTURE IMPLICATIONS 33

Common Aero Vehicle Systems—

Alternatives 6 Through 8

The common aero vehicle alternatives would offer much 

shorter response times than those of the aircraft-based alternatives for missions over long distances because of 

their hypersonic speeds. For missions where the launch 

platform can loiter close to target areas, the CAVs do not 

perform as well because their launchers must be located at 

a considerable distance from enemy territory—at a secure 

base or on a ship in the region for the medium-range 

CAV (Alternative 6), in the United States for the longrange CAV (Alternative 7), and several hundred miles 

away in low-Earth orbit for the space-based CAV (Alternative 8). The CAV alternatives would be much less expensive than developing new penetrating bombers, CBO 

estimates, but somewhat more expensive than the airlaunched missile in the arsenal-aircraft alternative (for the 

quantities considered). As was mentioned earlier, the 

quantity purchased under each CAV alternative was set to 

give the alternatives as similar a capability as possible. A 

constellation of five satellites in equatorial low-Earth orbit would provide the space-based CAV with a response 

time at least as good as that of the long-range surface 

CAV. In CBO’s alternative, arming each launcher with 

eight CAVs provided a launch mass well suited to available space-launch rockets. The resulting quantity totaled 

40 operational CAVs in orbit. However, satellites in lowEarth orbit typically have about a 10-year life in the harsh 

environment of space. Consequently, CBO assumed that 

two additional constellations’ worth of satellites would be 

needed to maintain that capability over about 30 years, a 

service life similar to what is often expected for new military aircraft. The surface-based alternatives had the same 

number of test and operational missiles as a single spacebased constellation did to provide similar total firepower.5

 Additional CAVs could be purchased under any 

of the alternatives, although the unit cost for the missiles 

under Alternative 7 would increase dramatically when the 

inventory of retired Peacekeeper missiles was exhausted 

and new intercontinental ballistic missile-sized rockets 

had to be purchased as well. A new rocket the size of a 

Peacekeeper would cost about $100 million and require 

new development, CBO estimates, more than tripling the 

cost of the round. Alternatively, it might be possible to 

purchase submarine-launched Trident D-5 boosters that 

are currently in production at about $40 million each and 

convert them for surface launch.6 The CAV missiles are 

much more expensive on a per-round basis than are Alternative 1’s air-launched missiles, but they would provide much higher speed and much harder hitting power. 

Because each medium-range CAV would have a lower 

unit cost, total costs associated with a medium-range 

CAV force would increase more slowly as purchase quantity increased.

High unit costs would probably make CAVs unsuitable 

for replacing aircraft in roles that require attacking large 

numbers of targets. For example, with aerial refueling 

support, 100 long-range supersonic cruise bombers (Alternative 5)—the fraction of a 150-aircraft fleet that 

might be committed to a conflict—could deliver a payload equivalent to about 2,100 JDAMs per day to a range 

of 7,000 nm.7

 The procurement cost for a similar number of space-based CAVs would total over $200 billion 

(see Figure 4-3). The costs for that number of weapons 

would be about $30 billion for the medium-range surface 

CAV and $80 billion for the long-range surface-launched 

CAV.8 The aircraft alternatives’ costs change little with 

increasing numbers of weapons delivered because the 

costs of those weapons are small compared with the costs 

of the aircraft. (Alternative 1 has the lowest cost, but as 

noted earlier, it is considerably less capable than the other 

alternatives.) Aside from the cost involved in achieving 

high delivery rates with CAVs, other practical difficulties 

exist. For example, forward deployment of several hundred medium-range CAVs would be a significant transportation burden, and substantial additional launch facilities would be needed to provide high rates of fire with 

5. Alternative 7 included half as many missiles, but each missile 

could deliver two CAVs. Although that arrangement would be less 

flexible than a one CAV/one missile configuration, a target of high 

enough value to warrant a CAV shot might warrant two warheads 

to improve the odds that the target would be destroyed.

6. The 2006 Quadrennial Defense Review includes plans to rapidly 

develop a system that would deliver conventional warheads on 

Trident missiles. Those missiles would probably be launched from 

Trident submarines instead of converted for launch from the 

ground or from surface ships.

7. CBO used 100 aircraft, not the entire 150-aircraft force, to reflect 

aircraft that might not be mission-capable at any given time. That 

distinction was less important for aircraft-to-aircraft comparisons. 

CBO used entire inventories under the assumption that comparable fractions of each type would be operational.

8. The unit cost of the long-range surface-launched CAVs that 

require new production of boosters is more than double that of 

the medium-range version but provides two CAVs per shot.
34 ALTERNATIVES FOR LONG-RANGE GROUND-ATTACK SYSTEMS

Figure 4-3.

Cumulative Development and Acquisition Costs for Weapons and Their Delivery 

Systems, by Number of Weapons Used

(Billions of 2006 dollars)

Source: Congressional Budget Office.

Notes: Assumes aircraft are delivering 2,000-pound Joint Direct Attack Munitions (JDAMs).

nm = nautical miles.

Alternative 1 = Arsenal aircraft

Alternative 2 = Medium-range subsonic bomber

Alternative 3 = Medium-range supersonic dash bomber

Alternative 4 = Long-range subsonic bomber

Alternative 5 = Long-range supersonic cruise bomber

Alternative 6 = Medium-range surface-based common aero vehicle

Alternative 7 = Long-range surface-based common aero vehicle

Alternative 8 = Space-based common aero vehicle

long-range surface CAVs. Similarly, large numbers of 

space-based CAVs would require a proportionally larger 

number of Evolved Expendable Launch Vehicles to put 

them in orbit and hence might require an expansion of 

the nation’s space-launch infrastructure. Consequently, 

CAVs most likely would be cost-effective only against 

high-value targets that typically exist in small numbers. 

However, as was discussed earlier, a combination of longrange CAVs and medium-range bombers could conceivably replace long-range bombers if DoD decided that sufficient CAVs could be purchased to handle the number of 

targets that would require attack from global distances.

It might also prove cost-effective to purchase a combination of the missiles in Alternatives 6 and 7. Much of the 

research and development cost, particularly that of the reentry vehicle, could be the same for the two systems. The 

medium-range CAVs, which could be purchased in larger 

quantities for a given level of investment, could be stationed at forward locations such as Guam or on ships so 

as to be in a position to provide short response times in 

areas of heightened tension, and the longer-range missiles 

could be saved for circumstances when the mediumrange systems were not located close enough to targets 

that might arise.

0

50

100

150

200

250

300

350

400

0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000

Alternative 1

Number of Weapons Used

Alternative 6

Alternative 2

Alternative 4

Alternative 3 Alternative 7

Alternative 5

Alternative 8

Approximate number of 2,000-pound

JDAMs deliverable per day by

100 Alternative 5 bombers based

7,000 nm from their targets
CHAPTER FOUR COST AND FORCE-STRUCTURE IMPLICATIONS 35

The Relative Difficulty of Developing 

the Long-Range Strike Alternatives 

Considered by CBO

The force-structure comparisons described above are in 

the context of fully operational forces that might eventually be fielded. Those comparisons do not consider the 

different lengths of time for development and procurement that might be needed to realize such forces, a factor 

that could be important as threats evolve and as existing 

systems age and are retired. The time required to develop 

a weapon system is influenced by many factors, some of 

which are inherent to the system (for example, the maturity of component technologies) and others that are external to the system (for example, funding levels and institutional support). This section briefly discusses how factors 

that are inherent to developing new systems could influence how soon the alternatives examined by CBO might 

be fielded.

Determining a schedule on which the development of a 

long-range strike alternative might proceed requires detailed information regarding the work and testing to be 

accomplished. CBO lacks that information for the alternatives considered in this study, and even if such information were available, DoD’s experience indicates that predicting schedules for any of its major programs before 

they are well under way is problematic. Although CBO 

cannot provide definitive schedules for developing longrange strike alternatives, it can provide observations

indicating the relative difficulty of implementing those 

alternatives.

The United States does not currently have an operational 

supersonic cruise missile, but other nations, such as Russia and India, do. The supersonic missiles that currently 

exist, however, lack the range and payload postulated for 

the missile used in the arsenal-aircraft alternative considered by CBO. Nonetheless, the United States has investigated the technologies needed for such a missile for a 

number of years. For example, in April 2002, the Defense 

Threat Reduction Agency solicited information on technology available for executing an advanced concept technology demonstration program for a supersonic cruise 

missile. Because supersonic cruise missiles exist and the 

technology needed to build them is relatively well understood, the arsenal aircraft (Alternative 1) would probably 

require less time to develop than the other alternatives for 

long-range strike considered by CBO.

Although the United States has test-flown maneuvering 

reentry vehicles, it must still develop the technology to 

field an operational CAV. In particular, materials would 

have to be developed that could withstand for up to 30 

minutes the heat generated by the CAV’s hypersonic 

flight through the atmosphere as it maneuvered to strike 

its intended target. In addition, although components of 

existing boosters might be used for the medium-range 

surface-based CAV, the integration of those components 

could prove problematic, as has been the case in an

ongoing program to develop and deploy ballistic missile 

defenses. And the protective satellite that would house 

the space-based CAVs would have to be designed and 

tested. Therefore, the time and effort needed to develop 

either surface-based or space-based CAVs (Alternatives 6, 

7, and 8) would most likely be greater than that to develop a supersonic cruise missile delivered by an arsenal 

aircraft.

The medium-range bombers (subsonic and with supersonic dash, Alternatives 2 and 3) and long-range subsonic 

bomber (Alternative 4) would all be based largely on existing technology, much of which has already been implemented in operational aircraft. Nonetheless, their development would require new aircraft designs (not merely 

modifications to existing designs), as well as the integration of a large number of subsystems, including complex 

software supporting the aircraft’s flight and operation of 

its sensor systems. Therefore, those alternatives would 

probably take longer to develop than would the supersonic cruise missile or the common aero vehicle.

Of all the alternatives considered by CBO, the long-range 

supersonic cruise bomber (Alternative 5) would most 

likely require the greatest effort and time to develop. Although the United States has operated and test-flown supersonic bombers and reconnaissance aircraft in the past, 

many years have passed since a U.S. manufacturer designed such an aircraft in detail. Moreover, incorporating 

some amount of stealth (or radar cross-section reduction) 

in a supersonic cruise bomber would probably require the 

use of advanced materials not incorporated in past designs. As with the subsonic bombers, developing a supersonic bomber would require integrating a large number 

of subsystems and complex software. Achieving the 

engine fuel efficiencies postulated by CBO for this alternative would also require additional development of

technology.

Appendix:

The Methodology Behind the Cost Analysis

The Congressional Budget Office (CBO) developed 

several alternatives for maintaining and improving the 

long-range strike capabilities of the U.S. military into the 

next decade. Those alternatives include upgrading tactical 

missile capabilities, improving the fleet of bomber aircraft, and building maneuverable reentry vehicles that are 

launched from ballistic missiles on the ground or from 

satellites in space.

For each alternative, CBO estimated the costs to develop 

and procure the weapon system, as well as the costs to improve or build the facilities and infrastructure needed to 

support the system. 

Expenses in the development phase include the cost to 

design and build the components of the long-range strike 

system, the cost to test those components to ensure that 

they meet performance requirements, and the cost to integrate the system into the military’s infrastructure and 

support systems. Expenses in the procurement phase include the cost of special tools and equipment to manufacture system components; the cost of hardware, material, 

and fabrication such as finished components and raw materials; and the cost to assemble the final product. Hardware, material, and fabrication are also important for determining estimates because they are inputs to statistical 

relationships used to estimate costs for nonrecurring design and other support costs.

All of the cost estimates in this appendix are presented in 

2006 dollars. Significant uncertainty exists about the capabilities, technologies, and costs associated with developing, purchasing, and operating weapon systems envisioned in the alternatives. Because the programs are either 

conceptual in nature or in the early stages of development, they entail a greater risk of cost and schedule overruns than do programs that are better defined and based 

on proven technologies. CBO’s cost estimates represent 

one possible outcome, calculated under specific assumptions regarding technologies and capabilities. Although 

CBO attempted to account for that risk, those estimates 

will change, perhaps significantly, as the designs of the 

systems in the alternatives become more fully defined.

The Cost of Supersonic Cruise

Missiles for the Arsenal Aircraft

In Alternative 1, the Air Force would develop and procure a new supersonic cruise missile that would be 

launched from an arsenal aircraft. Because the arsenal aircraft would be a modified version of an existing airframe 

(the C-17), for which the costs are generally known, this 

discussion focuses primarily on the methodology used to 

develop the cost of developing and procuring the missile. 

The need to purchase additional C-17 aircraft would depend in large part on future airlift requirements. The projected fleet of 180 C-17 aircraft might be sufficient to 

perform the long-range strike mission without critically 

hampering concurrent airlift efforts; thus, there would be 

little additional costs beyond that of the missiles. However, if the existing fleet of aircraft was not sufficient to 

meet that new requirement, additional C-17s would need 

to be purchased. That could substantially increase the total cost of the arsenal aircraft alternative. On the basis of 

recent acquisition cost data from the ongoing procurement program, CBO estimated, for example, that acquiring 15 additional C-17s for that purpose would cost 

about $3.3 billion. That estimate assumes those aircraft 

would be purchased at the end of current planned production, before the assembly line was shut down. If the 

decision to purchase additional aircraft was delayed beyond 2008, that assembly line would have to be reestab-
38 ALTERNATIVES FOR LONG-RANGE GROUND-ATTACK SYSTEMS

Table A-1.

Characteristics of Supersonic Missiles 

for the Arsenal Aircraft (Alternative 1)

Source: Congressional Budget Office.

Note: Mach is the ratio of the speed of an object to the speed of 

sound in air.

lished. In that case, it would cost more to acquire additional aircraft. 

Several variables for the performance parameters and design of a supersonic cruise missile drive the cost of such a 

weapon, although the exact values of those variables are 

not known at this time. For this study, CBO assumed 

that the missile would be capable of traveling 500 nautical miles and would carry a 1,000-pound warhead (see 

Table A-1 for a listing of the missile’s characteristics). 

The most important variable is the required speed of the 

weapon, which would affect the design—and thus the 

cost—of the propulsion system. The missile considered 

in this study would use a ramjet propulsion system with a 

top speed of Mach 3.1, 2 The cost of a supersonic missile 

is also affected by the type of warhead chosen for the system. CBO assumed that the missile would employ a lessexpensive unitary warhead rather than precision submunitions that would require more advanced guidance and 

control systems to permit complex maneuvers by the missile in the moments before it reached its target. CBO estimated that the cost to develop and procure 2,000 such 

supersonic cruise missiles would total $4.3 billion, including the cost to integrate the weapon with a delivery 

aircraft such as the C-17 cargo plane. On average, it 

would cost $2.2 million to acquire those missiles (see 

Table A-2 for a summary of acquisition costs for this alternative). 

CBO used several sources to estimate the development 

and procurement costs of a new supersonic cruise missile, 

such as methods and data contained in a 1998 cost estimate from the Naval Center for Cost Analysis for a ramjet missile, as well as information on hardware costs from 

existing ramjet/scramjet efforts.3 CBO also looked at data 

from prior tactical missile programs and other cost studies (see Table A-3 for a summary of the methods used to 

estimate development and procurement costs for this alternative).

CBO’s estimates for development and procurement are 

broken down into costs for: 

B Hardware, material, and fabrication;

B Nonrecurring design, testing, and tooling; and 

B Other support such as program management, initial 

maintenance plans, and contractor fees.

Hardware, Material, and Fabrication

Hardware, material, and fabrication includes the cost of 

purchasing finished components and raw materials from 

subcontractors, as well as the cost of recurring labor associated with assembling the final product. Those costs are 

historically the most significant part of the cost estimate 

for missile production and also constitute a small portion 

of costs in the development phase. Hardware, material, 

1. Mach is a ratio of the speed of an object to the speed of sound in 

the air or fluid in which it is traveling. At standard sea-level conditions, Mach 1 is 1,225 kilometers/hour (766 miles per hour) in 

the atmosphere.

2. In a typical turbojet engine, pressure is maintained in the combustion chamber through the use of a compressor fan. In contrast, a 

ramjet propulsion system uses the forward speed of the vehicle to 

“ram” external air into the combustion chamber to create the high 

pressure required for combustion. However, air entering a ramjet 

engine must be slowed down, as combustion can only take place 

at subsonic speeds, which limits a ramjet’s top speed to about 

Mach 5. New supersonic combustion ramjet (scramjet) technology is attempting to overcome that limitation by allowing combustion to occur at supersonic speeds.

Variable

Launch Weight (Pounds) 4,000

Maximum Speed Mach 3

Payload 1,000-pound warhead

Range (Nautical miles) 500

Engine Design Ramjet

Number of Engines 1

3. Jeff Cherwonik, William Stranges, and Jeff Wolfe, Generic Supersonic Cruise Missile Life Cycle Cost Estimate, prepared by the Naval 

Center for Cost Analysis in support of the Hard and Deeply Buried Target Defeat Capability Weapon Analysis of Alternatives 

(Arlington, Va.: Naval Center for Cost Analysis, October 1998).
APPENDIX: THE METHODOLOGY BEHIND THE COST ANALYSIS 39

Table A-2.

Acquisition Costs of Supersonic

Missiles for the Arsenal Aircraft

(Alternative 1)

(Billions of dollars)

Source: Congressional Budget Office.

a. Includes the cost of purchasing finished components and raw 

materials from subcontractors and the cost of recurring labor 

associated with assembling the final product.

b. Includes one-time costs that do not vary with the total number 

of missiles produced. Those costs include initial design and 

engineering efforts, software development, systems testing and 

evaluation, flight-testing, and platform integration.

c. Includes costs for contractor and government program management, data collection, contractor fees, and initial maintenance agreements.

and fabrication are also important for cost-estimating 

purposes because they are inputs to statistical relationships CBO used to estimate costs for nonrecurring design 

and other support costs. 

Tactical missiles typically contain four main hardware 

components: the engine, the airframe, the guidance and 

control system, and the warhead. In addition, CBO assumed that each missile would require a booster rocket to 

accelerate the weapon to a speed sufficient to operate the 

ramjet.4

 CBO estimated that hardware, material, and 

fabrication for the supersonic cruise missile would cost 

$140 million for the development phase and about $1.6 

billion for the procurement phase.

CBO approximated the cost for the missile engine on the 

basis of the material and fabrication costs of propulsion 

hardware in the X-43A hypersonic research aircraft, the 

GQM-163 missile (a supersonic sea-skimming target 

used to test shipboard defensive systems), and the Scramjet Engine Demonstration (SED) program.5

 The airframe cost estimate is based on the cost of other missile 

airframes, such as the Joint Standoff Weapon (JSOW), 

with adjustments for weight and material to account for 

the higher temperatures that a supersonic cruise missile 

would endure during flight.6 The cost estimates for the 

guidance and control and warhead subsystems are based 

on analogies to other missile programs such as the Tomahawk cruise missile and the JSOW. 

CBO assumed that the missile payload would consist of a 

unitary warhead, although it is possible that the Department of Defense (DoD) might add precision submunitions to a supersonic strike missile. However, such proposals would create additional technical challenges and 

costs that are not included in CBO’s estimate. CBO used 

the cost of the Mk 72 booster from the Navy’s Standard 

missile as an analogy to estimate the potential cost of the 

booster rocket because the Mk 72 propels a load that 

would be similar in weight to the proposed supersonic 

cruise missile. (CBO assumed that the missile and the 

booster considered in this alternative would weigh about 

4,000 pounds.)

Cost

Research and Development

Hardware, material, and fabricationa 0.1

Nonrecurring design, testing, and toolingb 0.8

Other supportc 0.6

___

Subtotal, research and development 1.5

Procurement (2,000 missiles)

Hardware, material, and fabrication 1.6

Nonrecurring design, testing, and tooling 0.2

Other support 1.0 ___

Subtotal, procurement 2.8

Total Estimated Acquisition Costs 4.3

4. Ramjet engines use external air speed, generated by the velocity of 

the vehicle itself, to create the pressure in the engine necessary for 

combustion, but the air speed must first be provided by some 

other means before the ramjet engine can function. While there 

are several ways to generate that speed in a tactical missile system, 

CBO assumed this missile would use a solid rocket booster that 

would be jettisoned once the missile reached the necessary speed.

5. The costs can only be approximated because the programs mentioned above are not direct analogies to a missile propulsion system of the type that would be used in a new supersonic cruise 

missile. The scramjets used in the National Aeronautics and Space 

Administration’s X-43A and the Air Force and the Defense 

Advanced Research Projects Agency’s SED programs are only 

meant to be demonstration articles for use in testing and proving 

concepts. The GQM-163 is a missile used by the U.S. Navy for 

training and testing purposes. The propulsion system is a solidfuel ducted rocket ramjet and would not be powerful enough to 

propel the strike weapon discussed in this study.

6. For information on the level of effort and cost involved with using 

different types of airframe materials, see Obaid Younossi, Michael 

Kennedy, and John C. Graser, Military Airframe Costs: The Effects 

of Advanced Materials and Manufacturing Processes, MR-1370-AF, 

(Arlington, Va.: RAND Project Air Force, 2001).
40 ALTERNATIVES FOR LONG-RANGE GROUND-ATTACK SYSTEMS

Table A-3.

Summary of CBO’s Cost Estimating Methods for Supersonic Missiles in 

Alternative 1

Source: Congressional Budget Office.

Note: JASSM = Joint Air-to-Surface Standoff Missile; JSOW = Joint Standoff Weapon; SED = Scramjet Engine Demonstration.

Research and Development Procurement

Nonrecurring Hardware Design, Testing, 

and Tooling

Statistical cost estimating relationships 

were used that relate nonrecurring costs 

to the average cost of the first 1,000 

production units and the time required for 

development. Also, test results were 

extrapolated from the JASSM program and 

increased by 50 percent.

Statistical cost estimating relationships 

were used that relate nonrecurring costs 

to the average cost of the first 1,000

production units.

Hardware, Material, and Fabrication

Engine Costs were based on information from 

Hyper-X, SED, and GQM-163 Coyote

propulsion hardware.

A step-down factor was estimated on the 

basis of the cost of this hardware in the 

research and development phase.

Airframe A step-up factor was estimated on the 

basis of the cost of this hardware in the 

procurement phase.

Costs were based on those for the JSOW 

system (dollars per pound) and adjusted 

for weight and materials.

Guidance and control A step-up factor was estimated on the

basis of the cost of this hardware in the 

procurement phase.

Costs were based on those for the JSOW, 

SLAM-ER, and Tomahawk systems.

Warhead A step-up factor was estimated on the

basis of the cost of this hardware in the 

procurement phase.

Costs were based on those for the 

Tomahawk and other historical missile 

systems.

Booster rocket A step-up factor was estimated on the

basis of the cost of this hardware in the 

procurement phase.

The Mk 72 booster was used as an 

analogy, but costs were adjusted to 

account for supersonic speeds.

Spares and support equipment A percentage was added to the cost of all 

hardware.

A percentage was added to the cost of all 

hardware.

Other Support Statistical cost estimating relationships 

were used that relate support costs to 

hardware, material, and fabrication costs. 

Contractor fees were included, which 

added 15 percent to contractor costs.

Statistical cost estimating relationships 

were used that relate support costs to 

hardware, material, and fabrication costs. 

Contractor fees were included, which 

added 15 percent to contractor costs.
APPENDIX: THE METHODOLOGY BEHIND THE COST ANALYSIS 41

CBO relied on data from the production programs of the 

weapon systems just mentioned to estimate procurement 

costs for the airframe, the guidance and control system, 

the warhead, and the rocket booster. CBO adjusted those 

data to calculate the cost of the first production unit for 

each of the major components and then applied learning 

curves to estimate the hardware costs for 2,000 units.7

For the estimate for the supersonic strike missile, CBO 

selected a learning curve of 90 percent, consistent with 

that in five other missile and munitions programs. 

In contrast, CBO derived the cost of the engine by estimating the first set of hardware built during the research 

and development phase (because data on production engines were not available, CBO used engine cost data from 

development prototypes) and then used a “step-down” 

equation to estimate the cost of the first production unit. 

A step-down equation is based on the premise that fabrication in the development phase is usually more expensive because the units are being assembled at lower quantities and do not always have the benefit of special 

manufacturing tools and other efficiencies available in the 

production phase. For this estimate, CBO used an equation based on historical missile costs that relates the cost 

of the first unit in the development phase to the cost of 

the first unit in the production phase.8 After estimating 

the cost of the first production engine, CBO applied a 

production learning curve to estimate the cost to procure 

2,000 engines.

In addition to the 2,000 production units, CBO assumed 

60 missiles would be built in the development phase. The 

Air Force would use those missiles to test and validate the 

missile design. Except for their engines, the cost of hardware, material, and fabrication for missiles built in the development phase was estimated using “step-up” equations, which are the inverse of step-down equations. 

CBO then estimated the cost of the 60 development missiles using a learning curve similar to that used for the 

production missiles.

To complete the cost estimates for hardware, material, 

and fabrication, CBO added costs for final integration 

and system checkout, initial spares, and support equipment (such as containers to transport the missiles). Those 

estimates were based on factors derived from other missile 

programs that were applied to the recurring hardware 

costs.

Nonrecurring Design, Testing, and Tooling

This category includes all of the one-time costs that are 

not necessarily dependent on the total number of missiles 

that would be purchased. It includes initial design and 

engineering efforts, systems testing and evaluation (including flight-testing), tools to build missiles, software 

development, and efforts to integrate the missile with a 

delivery aircraft. CBO estimated that the nonrecurring 

costs for the missile hardware in the research and development phase would total about $800 million. 

About 85 percent of the nonrecurring costs in the research and development phase are for initial design and 

engineering as well as systems testing and evaluation. Design and engineering estimates are based on a statistical 

relationship that relates the cost of those efforts to the 

length of the development phase and the average cost of 

the first 1,000 production units. For that estimate, CBO 

assumed that the development effort would last about 

eight years on the basis of the development time of other

7. Learning curves are based on the theory that each production unit 

will be easier to produce than the previous unit because of the 

increased experience of workers and other efficiencies. The curve 

is generally expressed as a logarithmic relationship; however, it is 

frequently described as a percentage decrease in cost or labor hours 

each time the number of units produced doubles. For this estimate, CBO used a learning curve of 90 percent, which means the 

hardware for the second unit would cost 90 percent of the cost of 

the first unit, and the fourth unit would cost 90 percent of the 

cost of the second unit, and so on. A learning curve equation can 

also incorporate a coefficient to account for efficiencies gained by 

increasing the production rate. For this estimate, CBO used a rate 

coefficient of 95 percent and assumed that the 2,000 missiles 

would be purchased in lots of approximately 175 each year.

8. For this cost estimate, CBO used step-up/step-down factors and 

equations contained in Paul L. Hardin and Daniel Nussbaum, 

Analysis of the Relationship Between Development and Production 

Costs and Comparisons with Other Related Step-up/Step-down Studies (Arlington, Va.: Naval Center for Cost Analysis, January 1994).
42 ALTERNATIVES FOR LONG-RANGE GROUND-ATTACK SYSTEMS

missile systems, with additional allowance for the design 

and testing of new technologies.9

CBO used several methods to estimate costs for systems 

testing and evaluation, including a statistical relationship 

that uses missile weight and development time as independent variables, as well as actual costs from the Air 

Force’s Joint Air-to-Surface Standoff Missile (JASSM) 

program. Because the United States does not currently 

use ramjets in its tactical missiles, data from historical 

programs may not accurately estimate the cost of testing 

that new technology. To account for that uncertainty, 

CBO increased by 50 percent the estimates for systems 

testing and evaluation produced using the historical data.

Although most nonrecurring costs are incurred in the research and development phase, CBO estimated that there 

would be about $170 million in nonrecurring costs in the 

procurement phase for the special tooling and facilities 

needed for full-rate production of the missile. CBO estimated those costs using a statistical relationship that relates such tooling and facilities costs to missile hardware 

costs.

Other Support

CBO estimated that other support costs would total 

$590 million in the research and development phase and 

$960 million in the procurement phase. Those costs 

comprise expenses for data collection, contractor fees and 

program management expenses, warranties and initial 

maintenance plans, and government program management expenses. 

Program management is the largest component of that 

category. For the research and development phase, CBO 

estimated those costs using a statistical cost estimating relationship that incorporates the development time and 

nonrecurring design costs as independent variables. For 

the procurement phase, program management is generally a percentage of the recurring hardware costs adjusted 

for the lot number because program management costs 

are generally higher in earlier procurement lots. 

Contractor fees are another large component of other 

support costs. For that estimate, CBO assumed that contractor fees would be 15 percent of contractor costs in 

both the research and development and procurement 

phases. 

The Cost of Bomber Aircraft

CBO also estimated the cost of developing and producing four types of bomber aircraft to provide long-range 

strike capability: a medium-range subsonic bomber, a 

medium-range supersonic bomber, a long-range subsonic 

bomber, and a long-range supersonic bomber (see 

Table A-4 for a listing of the notional characteristics of 

those aircraft). 

In Alternative 2, the Air Force would develop and purchase a stealthy medium-range subsonic bomber with an 

empty weight of 60,000 pounds that would be able to 

carry a payload of 20,000 pounds to a range of 1,500 

nautical miles without refueling.10 It would be able to 

cruise at speeds of around Mach 0.85 using two engines 

that would be derived from existing engine designs, such 

as the General Electric F118 currently used to power the 

B-2 bomber. By CBO’s estimates, the cost to develop 

such an aircraft would total approximately $19 billion 

and the cost to purchase 275 of those bombers—enough 

to replace the current fleet of F-15E and F-117 strike aircraft—would total $52 billion.

9. For this estimate, CBO included only those development costs 

that would be incurred once the initiation of a formal acquisition 

program had begun. Generally, the estimates include all costs associated with the “system development and demonstration phase” of 

the updated DoD Directive 5000 (DoD Directive 5000.1, “The 

Defense Acquisition System,” October 23, 2000). However, the 

estimates include some costs in the “concept and technology demonstration phase,” because those activities were included in “program definition and risk reduction activities” prior to the update 

of DoD 5000 in October 2000. The estimates do not include current and planned expenditures needed to bring the necessary technologies to maturity. For instance, the Air Force, Navy, and 

Defense Advanced Research Projects Agency will all be contributing hundreds of millions of dollars over the next several years to 

research various ramjet/scramjet technologies to prove that they 

have practical applications for a variety of military weapon systems. Those costs are not included here.

10. Empty weight comprises the weight of the airframe, engines, avionics and electronics, weapons, and other support equipment. It 

excludes the weights of the crew, payload, fuel, and oil.
APPENDIX: THE METHODOLOGY BEHIND THE COST ANALYSIS 43

Table A-4.

Characteristics of Bomber Aircraft

Source: Congressional Budget Office.

Note: Alternative 2 = Medium-range subsonic bomber

Alternative 3 = Medium-range supersonic dash bomber

Alternative 4 = Long-range subsonic bomber

Alternative 5 = Long-range supersonic cruise bomber

a. The ranges shown are the maximum distance from an air base or launcher location to the target. For the aircraft alternatives, the total 

distance flown on a maximum-range mission would be double the values shown.

In Alternative 3, the Air Force would develop and purchase a stealthy medium-range supersonic bomber conceptually based on either the F-22 or YF-23 fighter.11 It 

would have an empty weight of 59,000 pounds and be 

able to carry a payload of 10,000 pounds to a range of 

1,500 nautical miles without refueling. Using two engines based on an existing design such as the F-22’s afterburner-equipped Pratt and Whitney F119, it would be 

able to cruise at subsonic speeds of around Mach 0.85 

and dash to speeds in excess of the speed of sound—up to 

Mach 1.5—although the bomber’s range would be reduced substantially when flying at speeds faster than 

Mach 1.0. According to CBO’s estimates, the cost to develop such an aircraft would total approximately $23 billion and the cost to purchase 275 of those bombers 

would total $61 billion.

In Alternative 4, the Air Force would develop and purchase a highly stealthy long-range subsonic bomber with 

an empty weight of 128,000 pounds that would be able 

to carry a payload of 40,000 pounds to a range of 2,500 

nautical miles without refueling. It would be able to 

cruise at speeds of about Mach 0.85 using improved versions of existing engines, such as the General Electric 

F118. Those improvements and other changes would allow the use of two engines on this new aircraft, compared 

with the four used to power the B-2 bomber. By CBO’s 

estimates, the cost to develop such an aircraft would total 

approximately $31 billion and the cost to purchase 150 

of those bombers—enough to replace the current fleet of 

B-52 and B-1 bomber aircraft—would total $61 billion.

In Alternative 5, the Air Force would develop and purchase a long-range supersonic cruise bomber with an 

empty weight of 165,000 pounds that would be able to 

carry a payload of 40,000 pounds to a range of 2,500 

nautical miles without refueling. It would be capable of 

cruising at Mach 2.4 using four newly designed engines. 

Although this aircraft would employ some stealth features, it would not rely on stealth as extensively as the 

slower bombers described above. The cost to develop 

such an aircraft would total approximately $69 billion 

and the cost to purchase 150 of those bombers would total $137 billion, CBO estimates (see Table A-5 for a summary of the costs to acquire the aircraft described above).

Alternative 2 Alternative 3 Alternative 4 Alternative 5

Empty Weight (Thousands of pounds) 60 59 128 165

Maximum Speed Mach 0.85 Mach 1.5 Mach 0.85 Mach 2.4

Payload (Thousands of pounds) 20 10 40 40

Range (Unrefueled, in nautical miles)a 1,500 1,500 2,500 2,500

Engine Design Derivative Derivative Derivative New

Number of Engines 2 2 2 4

Afterburning Engine No Yes No Yes

11. The F-22 fighter was designed by Lockheed Martin for the Air 

Force’s advanced tactical fighter program and was selected by the 

Air Force for further development and production. The YF-23 

fighter was the design submitted by the team of Northrop 

Grumman and McDonnell-Douglas.
44 ALTERNATIVES FOR LONG-RANGE GROUND-ATTACK SYSTEMS

Table A-5.

Acquisition Costs of Aircraft in Alternatives 2, 3, 4, and 5

Source: Congressional Budget Office.

Note: Alternative 2 = Medium-range subsonic bomber

Alternative 3 = Medium-range supersonic dash bomber

Alternative 4 = Long-range subsonic bomber

Alternative 5 = Long-range supersonic cruise bomber

The models and equations CBO used to develop the aircraft characteristics were discussed in Chapter 2. CBO estimated the costs to develop and procure each of the 

bomber aircraft described above using a common set of 

estimating methodologies (see Table A-6 for a summary 

of those methods).

Research and Development Costs

Research and development costs include several components: concept and technology development; engineering 

design; and other development costs such as prototype 

manufacturing, testing and evaluation, systems engineering and program management, integrated logistics

support, contractor fees, and government program 

management. 

Concept and technology development includes the exploration of early approaches and designs needed to provide 

certain capabilities, as well as the development of new 

technologies and components needed to enable the new 

system to meet performance parameters. CBO estimated 

those costs using analogies to other aircraft development 

programs such as the B-2 bomber, F/A-18 fighter, and 

the F-22 fighter. In developing those estimates, CBO also 

considered whether the concept development effort 

would most likely be awarded to multiple contractors, as 

well as whether flying prototypes would be built. (For instance, contractors Boeing and Lockheed Martin were 

both hired to develop technology and designs for the 

Joint Strike Fighter and built flying prototypes as part of 

the competition to determine which design would be selected for the systems development and demonstration 

phase.) 

Research and Development

Concept and technology development 5 4 3 4

Systems development

Airframe 5 7 9 25

Engine 1 1 4 4

Avionics 3 4 7 15

Other development 5 7 8 21 __ __ __ __

Subtotal, development 19 23 31 69

Procurement

Flyaway

Airframe 24 27 28 63

Engine 2 4 2 5

Avionics 5 6 6 13

Other procurement costs 21 24 25 56 __ __ __ ___

Subtotal, procurement 52 61 61 137

Military Construction 1 1 1 1

Total Estimated Acquisition Costs 72 85 93 207

Memorandum:

Quantity of Aircraft Procured 275 275 150 150

Alternative 2 Alternative 3 Alternative 5 Alternative 4
APPENDIX: THE METHODOLOGY BEHIND THE COST ANALYSIS 45

Table A-6.

Summary of CBO’s Cost Estimating Methods for Aircraft in

Alternatives 2, 3, 4, and 5

Source: Congressional Budget Office.

Research and Development Procurement

Hardware, Material, and Fabrication

Airframe A statistical cost estimating relationship 

developed by RAND was used to calculate 

engineering and design hours on the basis 

of an aircraft’s empty weight and 

maximum speed, adjusted for the cost of 

working with advanced materials.

A statistical cost estimating relationship 

developed by RAND was used to calculate 

the cumulative average cost of materials, 

engineering hours, tooling hours, 

manufacturing hours, and quality 

assurance hours for 100 aircraft on the 

basis of an aircraft’s empty weight and 

maximum speed, adjusted for the cost of 

working with advanced materials.

Engine A statistical cost estimating relationship 

developed by RAND was used to calculate 

the cost of engine development on the 

basis of engine rotor inlet temperature, 

specific fuel consumption, the number of 

test hours, and whether the engine was 

derived from an existing design.

A statistical cost estimating relationship 

developed by RAND was used to calculate 

the theoretical cost to produce the first 

engine (that cost was based on engine 

rotor inlet temperature, the aircraft’s 

empty weight, and whether the engine 

was equipped with an afterburner). Costs 

for total production were estimated using 

a 90 percent learning curve.

Avionics Costs were calculated as a percentage of 

the cost to develop the engine and 

airframe, using as a basis the Joint Strike 

Fighter and F-22 development programs.

Costs were calculated as a percentage of 

the cost to develop the engine and airframe, using as a basis the B-2, F/A-18E/F, 

and F-22 development programs.

Spares and support equipment Not applicable. Costs were calculated as 15 percent and 

30 percent, respectively, of other hardware costs on the basis of average costs 

for other aircraft acquisition programs.

Other Support

Testing and evaluation A statistical cost estimating relationship 

developed by the Naval Cost Analysis 

Division was used to calculate flight-test 

costs on the basis of the aircraft’s unit 

weight, maximim speed, and flight-test 

hours plus the cost of producing test 

aircraft, which was stepped up from the 

production cost estimate.

Not applicable.

Program management Costs were calculated as a percentage of 

the sum of airframe costs and testing and 

evaluation costs.

Costs were calculated as a percentage of 

airframe costs.

Integrated logistics support Costs were calculated as a percentage of 

the sum of airframe costs and testing and 

evaluation costs.

Not applicable.
46 ALTERNATIVES FOR LONG-RANGE GROUND-ATTACK SYSTEMS

Engineering design includes the cost to design the airframe, engines, and electronic systems, as well as the cost 

to design the special tools and manufacturing equipment 

needed to build each of those components. CBO estimated airframe development costs using a cost estimating 

relationship formulated by RAND that takes into account the empty weight and maximum speed of the aircraft being designed, as well as the use of advanced materials such as titanium and carbon-thermoset composites 

in the design.12 CBO estimated engine development 

costs using another RAND cost estimating relationship 

that relates engineering development costs to the engine’s 

rotor inlet temperature, the engine’s specific fuel consumption, and the number of engine test hours in the development program. That method also takes into account 

whether the engine design will be derived from an existing engine or will be a brand new design.13,14

Analysts have developed several estimating relationships 

for calculating the cost to develop avionics systems, but 

the use of those methods requires extensive design specifications and other technology factors. Those specifications 

are not usually available for systems in the early concept 

phase, such as those considered in this study. Instead, 

CBO used the ratio of the total hardware development 

costs to the avionics development costs for the F-22 and 

the Joint Strike Fighter program to estimate avionics development costs for the bomber-aircraft alternatives. Although not as accurate as detailed cost estimating relationships, that method should produce a reasonable 

estimate of costs.

According to a study by the Institute for Defense Analyses, aircraft that feature a significant number of components that reduce the aircraft’s radio frequency and infrared signature cost approximately 30 percent more to 

design and build than do similarly sized aircraft without 

such components.15 Thus, CBO increased the estimated 

costs for airframe, engine, and avionics development by 

30 percent to account for the additional effort required to 

design the stealth features and the additional cost to develop the techniques and tools needed to manufacture 

those complex components.

Other development costs include the cost of testing and 

evaluation, systems engineering and program management (SE/PM), integrated logistics support, contractor 

fees, and government program management costs. Testing and evaluation costs include the cost of the flight-test 

program as well as the cost to build prototype airplanes 

and other equipment needed for testing. CBO estimated 

flight-test costs using a cost estimating relationship developed by the Navy that relates airframe weight, maximum 

speed, and the number of flight-test hours to the cost of 

testing and evaluation. CBO estimated the cost of prototypes using its aircraft production estimating methodology, which is discussed later in this section.

Both SE/PM and integrated-logistics-support estimates 

are based on a cost estimating relationship developed by 

the Navy that estimates those costs as a factor of airframe 

development and testing and evaluation. CBO estimated 

contractor fees—on the basis of proposals for other aircraft acquisition programs—at 15 percent of the sum of 

the development costs discussed above. Government program management costs were estimated at 75 percent of 

systems engineering and contractor program management costs plus 20 percent of systems test and evaluation 

costs. 

Finally, those costs were adjusted to account for cost 

growth during the time required to develop the aircraft. 

Research by RAND and the Government Accountability 

Office has demonstrated that cost analysts systematically 

underestimate the cost of developing and procuring major weapon systems. That tendency is particularly pronounced in estimates performed in the concept development and early design phases. In a study of 115 major 

defense acquisition systems, RAND calculated that, on 

average, estimates of development and procurement costs 

were too low by 25 percent and 18 percent, respec12. Younossi, Kennedy, and Graser, Military Airframe Costs: The 

Effects of Advanced Materials and Manufacturing Processes.

13. The rotor inlet temperature is defined as the temperature of the 

fuel/air combustion products as they enter the first section of 

rotating engine blades after leaving the stationary blades just aft of 

the combustion chamber. Higher rotor inlet temperatures are 

associated with higher thrust-to-weight or power-to-weight ratios. 

Specific fuel consumption for turbojet or turbofan engines is the 

ratio of the fuel flow rate to thrust generated—that is, pounds of 

fuel per hour to pounds of thrust. Lower ratios indicate moreefficient engines.

14. Obaid Younossi and others, Military Jet Engine Acquisition: Technology Basics and Cost-Estimating Methodology (Santa Monica, 

Calif.: RAND Project Air Force, 2002).

15. Bruce R. Harmon and others, Cost Estimating for Modern Combat 

Aircraft: Adjusting Existing Databases and Methods to Include LowObservable Cost Consideration (Alexandria, Va.: Institute for 

Defense Analyses, 2001).
APPENDIX: THE METHODOLOGY BEHIND THE COST ANALYSIS 47

tively.16 To account for that systematic bias, CBO increased the estimate of development costs by 25 percent.

Procurement Costs

Procurement cost estimates include flyaway costs—the 

recurring costs to manufacture and assemble the airframe, 

engine, and avionics systems—and other procurement 

costs, both recurring and nonrecurring. Other recurring 

costs include program management expenses, contractor 

fees, and other government costs. Nonrecurring procurement costs include the cost to set up the production facilities, tools, and manufacturing equipment. They also include the cost of support equipment that is unique to the 

airplane; simulators for pilot training; maintenance manuals and technical publications; and an initial complement of spare parts. 

CBO estimated airframe costs using cost estimating relationships developed by RAND that predict costs on the 

basis of inputs such as the aircraft’s empty weight, its 

speed, and the increased cost of working with advanced 

materials such as titanium and carbon thermosets. Engine 

costs were estimated using another RAND cost estimating relationship that considers factors such as the engine’s 

weight and its rotor inlet temperature. That equation also 

accounts for the cost of producing engines equipped with 

an afterburner.17 CBO calculated avionics costs as a percentage of total hardware costs on the basis of the ratio of 

those costs from the F-22 and F/A-18 programs.18 On 

the basis of the study by the Institute for Defense Analyses, CBO increased its estimate of the costs of the airframe, engine, and avionics by 30 percent to account for 

the additional effort of working with special stealth materials and structures designed to reduce the aircraft’s radar, 

thermal, visual, and electromagnetic signature.

CBO used two factors to estimate other recurring procurement costs. Combined program management costs 

for the contractor and the government are approximately 

11 percent of airframe procurement costs, whereas the 

contractor’s fee is estimated as 15 percent of other production costs for the contractor.

CBO used two methods to estimate other nonrecurring 

procurement costs. On the basis of actual costs from 

other aircraft acquisition programs, CBO estimated costs 

for other support equipment and initial spare parts at 30 

percent and 15 percent of flyaway costs, respectively. 

CBO used a cost estimating relationship developed by 

the Navy to estimate the cost of special tools and test 

equipment at roughly 1.5 percent of the costs of airframe 

procurement.

On the basis of the RAND study on cost growth in 

weapon-system acquisitions, CBO increased all procurement costs by 15 percent to account for that factor.

Military Construction

Because the bombers in CBO’s alternatives would replace 

existing planes, CBO assumed that many of the facilities 

used to house and maintain those aircraft would be available to support the new aircraft. However, the introduction of any new weapon system will require some new facilities or significant modifications to existing facilities. 

For instance, new buildings for simulators are often 

needed, and existing hangars may require modifications if 

they are not of the proper dimensions to accommodate 

new aircraft. On the basis of actual military construction 

costs for other aircraft acquisition programs, CBO estimated that such costs could range from $500 million to 

$1 billion, depending on the similarity between the new 

system and the aircraft it would replace. For that estimate, CBO included $1 billion in construction costs for 

each alternative.

Results

The costs to develop and acquire the four aircraft platforms considered for providing long-range strike capability would range from $72 billion to $207 billion.

Alternative 2. Acquiring 275 medium-range subsonic 

bombers would cost $72 billion, CBO estimates. In 

CBO’s estimate, developing the aircraft accounts for $19 

billion, or 26 percent of the total acquisition costs. Concept development accounts for $5 billion of those costs, 

including the cost to build several flying prototypes, 

16. J.A. Drezner and others, An Analysis of Weapon System Cost Growth 

(Santa Monica, Calif.: RAND Project Air Force, 1993).

17. Younossi and others, Military Jet Engine Acquisition: Technology 

Basics and Cost-Estimating Methodology.

18. Estimates of costs for avionics and electronics are often developed 

through the use of complex proprietary cost models like PRICE or 

through cost estimating relationships with inputs such as avionics 

weight or the level of technology integration. CBO did not define 

the avionics systems in the detail needed to use those cost estimating relationships. Rather, CBO estimated avionics costs as a percentage of total airframe and engine costs on the basis of recent 

production programs for high-performance aircraft such as the F22 and the F/A-18 E/F.
48 ALTERNATIVES FOR LONG-RANGE GROUND-ATTACK SYSTEMS

whereas the cost to develop the airframe, a derivative engine, and avionics account for another $9 billion. Other 

development costs account for the remaining $5 billion. 

Procurement costs, estimated at $52 billion, would be 72 

percent of the acquisition costs. By CBO’s estimates, it 

would cost $31 billion to produce 275 aircraft. Other 

production costs would total $21 billion. Military construction costs would account for the remaining 2 percent of acquisition costs. On average, each aircraft would 

cost $261 million to acquire.

Alternative 3. Acquiring 275 medium-range supersonic 

dash bombers would cost $85 billion, CBO estimates. 

Developing the aircraft would cost $23 billion, or 27 percent of the total acquisition costs. Including the cost to 

build several flying prototypes, concept development 

would account for $4 billion of those costs, slightly less 

than those for Alternative 2 because CBO assumed that 

some of the necessary development work had already 

been accomplished under the F-22 and the YF-23 programs. The cost to develop the airframe, a derivative engine, and avionics would account for another $12 billion. 

Other development costs would account for the remaining $7 billion. 

Procurement costs of $61 billion would account for 72 

percent of the acquisition costs, including $37 billion to 

build the aircraft, CBO estimates. Other procurement 

costs would total $24 billion. Military construction costs 

would account for the remaining 1 percent of acquisition 

costs. On average, each aircraft would cost $307 million 

to acquire.

Alternative 4. By CBO’s estimates, it would cost $93 billion to acquire 150 long-range subsonic bombers. Developing the aircraft would cost $31 billion, or 34 percent of 

the total acquisition costs. In CBO’s estimate, concept 

development would account for $3 billion of those costs, 

which CBO assumed would not include flying prototypes because of the high cost of building larger airplanes. 

The cost to develop the airframe, a derivative engine, and 

avionics account for $20 billion, whereas other development costs account for the remaining $8 billion. 

Procurement costs of $61 billion would constitute 65 

percent of the acquisition costs. It would cost $36 billion 

to produce 150 aircraft, CBO estimates. Other procurement costs would total $25 billion. Military construction 

costs would account for the remaining 1 percent of acquisition costs. On average, the aircraft would cost $627 million to acquire.

Alternative 5. Acquiring 150 long-range supersonic 

bombers would cost $207 billion, CBO estimates. Developing aircraft would cost $69 billion, or 33 percent of the 

total acquisition costs. Concept development would represent for $4 billion of those costs, which CBO assumed 

would not include flying prototypes. The cost to develop 

the airframe, a new engine, and avionics would account 

for $44 billion, whereas other development costs would 

account for the remaining $21 billion. 

Procurement costs of $137 billion would make up 66 

percent of the acquisition costs. It would cost $81 billion 

to produce 150 aircraft, CBO estimates. Other procurement costs would total $56 billion. Military construction 

costs would account for less than 1 percent of acquisition 

costs. On average, the aircraft would cost $1.38 billion to 

acquire.

Costs of the Common Aero

Vehicle System

The common aero vehicle (CAV) is a maneuverable reentry vehicle that delivers a weapon from space. CBO assumed that the CAV would carry a 1,000-pound warhead 

designed to penetrate hardened targets. CBO estimated 

the costs of three alternatives for employing CAVs in the 

long-range strike mission—two that would deploy CAVs 

aboard ground-based ballistic missiles and one that would 

deploy them aboard orbiting satellites.

In Alternative 6, the Army would deploy the CAVs 

aboard ground-based solid-fuel boosters powered by 

rocket motors similar to the Orion 50 built by Alliant 

Techsystems. CBO assumed that the Army would purchase a total of 48 CAVs, 48 rocket boosters, and 24 mobile launchers. Each booster would carry a single CAV, 

and two boosters would be deployed on each launcher. 

Four mobile launchers, eight boosters, and eight CAVs 

would be procured as spares. 

In Alternative 7, the Air Force would deploy the CAVs 

aboard ground-based Peacekeeper missiles that are being 

retired from use as strategic nuclear ballistic missiles. 

CBO assumed that the Air Force would purchase a total 

of 48 CAVs and convert 24 Peacekeepers to launch them. 

Each missile would carry two CAVs. CBO assumed that 
APPENDIX: THE METHODOLOGY BEHIND THE COST ANALYSIS 49

Table A-7.

Characteristics of Common Aero Vehicles in Alternatives 6, 7, and 8

Source: Congressional Budget Office.

Note: EELV = Evolved Expendable Launch Vehicle

Alternative 6 = Medium-range surface-based common aero vehicle

Alternative 7 = Long-range surface-based CAV

Alternative 8 = Space-based CAV

10 Peacekeeper missiles would be based at Cape Canaveral Air Station in Florida and 10 missiles would be based 

at Vandenberg Air Force Base in California. Four missiles 

and eight CAVs would be used as spares.

In Alternative 8, the Air Force would deploy the CAVs in 

space aboard satellites that would be placed into orbit by 

heavy launch vehicles such as the Evolved Expendable 

Launch Vehicle (EELV). The orbiting CAVs would use a 

rocket motor to bring them out of orbit to attack targets 

on Earth. CBO assumed that the Air Force would purchase 128 CAVs and 16 satellites. A constellation of five 

satellites, each carrying eight CAVs, would be continuously maintained in orbit. Because orbits decay and the 

harsh environment of space eventually degrades orbiting 

equipment, CBO assumed that the constellation would 

be replaced twice during a 30-year period, requiring a total of 120 CAVs and 15 satellites. Eight additional CAVs 

and one additional satellite would be purchased to replace 

any that might be lost in a launch failure (see Table A-7 

for a description of the technical characteristics of those 

alternatives).

By CBO’s estimates, acquisition costs would total about 

$4 billion for the ground-based alternatives and about 

$12 billion for the space alternative (see Table A-8 for a 

summary of the costs of those alternatives). CBO used 

several methods, discussed below, to estimate the costs of 

development, procurement, and facilities construction 

for those alternative methods of deploying the common 

aero vehicles (see Table A-9 for a summary of those 

methods).

Research and Development Costs

CBO estimated that the cost to develop the CAV weapon 

system and its various supporting components would total about $2.5 billion for the ground-based alternatives 

and about $4 billion for the space-based alternative. 

Those estimates include the costs to develop technology 

and produce designs for the various system components 

such as the common aero vehicle, booster vehicles, mobile launchers, rocket motors, orbital support system 

(protective satellite), and launch vehicles. They also include the cost to test and evaluate those components, as 

well as the cost to integrate them into a functioning system. There is significant uncertainty about the maturity 

of the technologies associated with the common aero vehicle, which results in a substantial risk that costs could 

exceed initial estimates. In its estimates, CBO used research by RAND for comparable systems to account for 

that risk. 

Common Aero Vehicle. CBO used DoD’s estimate of the 

development costs for a program called FALCON (Force 

Application and Launch from the Continental United 

States) as the basis for estimating development costs for 

the CAV. In the program, the Defense Advanced 

Research Projects Agency and the Air Force are developing hypersonic technologies needed for weapons that can

Launch Platform

Number of CAVs per Platform

Total Number of CAVs Deployed

Number of Spare CAVs

Number of Replacement CAVs

Payload per CAV

0 0 80

1,000-pound warhead 1,000-pound warhead 1,000-pound warhead

40 40 40

888

Peacekeeper missile EELV Heavy

128

Solid rocket booster

Alternative 6 Alternative 7 Alternative 8
50 ALTERNATIVES FOR LONG-RANGE GROUND-ATTACK SYSTEMS

Table A-8.

Acquisition Costs of Common Aero Vehicles in Alternatives 6, 7, and 8

(Billions of 2006 dollars)

Source: Congressional Budget Office.

Note: n.a. = not applicable.

rapidly strike targets over global ranges from launch platforms in the United States. Such technologies would give 

the United States the capability to build a weapon that 

could be used to promptly strike distant targets by traveling through space in a suborbital trajectory aboard a 

hypersonic vehicle. CBO assumed that development efforts for the CAV would be similar, given the common 

purpose and performance characteristics of those two 

systems.

Over the next several years, DoD plans continued investment in the program to evaluate the performance of

hypersonic technologies in realistic operating environments. The department hopes to launch three test vehicles as part of that program over the 2007-2010 period. 

On the basis of funding plans for those programs, CBO 

estimates that it could cost $620 million to develop an 

operational CAV weapon. That estimate is higher than 

the one in DoD’s plans for two reasons. First, systems engineering and program management efforts of formal acquisition programs typically cost about 33 percent more 

than such efforts in technology development programs 

like FALCON. Second, RAND’s research on cost growth 

in defense programs indicates that cost estimates performed early in the development phase tend to understate 

total development costs for space and missile programs by 

as much as 40 percent. 

Booster Vehicle. In Alternative 6, the Army would use 

solid-fuel rocket boosters to launch ground-based CAVs 

into a suborbital trajectory toward the target. On the basis of information from the Army, CBO estimated that it 

would cost about $140 million to modify existing booster 

designs to accommodate the CAVs. 

In Alternative 7, the Air Force would use Peacekeeper 

missiles to boost ground-based CAVs onto a suborbital 

trajectory. Development estimates include the costs to 

provide a new guidance and navigation system, the costs 

Research and Development

Common aero vehicles 0.6 0.6 0.6

Booster vehicles 0.1 0.5 n.a.

Mobile launcher 0.3 n.a. n.a.

Rocket motors n.a. n.a. 0.4

Protective satellites n.a. n.a. 0.6

Launch vehicles n.a. n.a. 0

Test and evaluation 1.0 1.0 1.7

System integration 0.4 0.4 0.7 ___ ___ ___

Subtotal, research and development 2.4 2.5 4.0

Procurement

Common aero vehicles 0.5 0.5 1.4

Booster vehicles 0.4 0.3 n.a.

Mobile launcher 0.3 n.a. n.a.

Rocket motors n.a. n.a. 0.1

Protective satellites n.a. n.a. 0.7

Launch vehicles n.a. n.a. 5.4 ___ ___ ___

Subtotal, procurement 1.2 0.9 7.7

Military Construction 0 0.6 0

Total Estimated Acquisition Costs 3.7 4.0 11.7

Alternative 6 Alternative 7 Alternative 8
APPENDIX: THE METHODOLOGY BEHIND THE COST ANALYSIS 51

to modify the missile’s propulsion system, and the costs 

to design a lighter deployment module and shroud.19

Materials to justify the budget indicate that the Air Force 

spent about $400 million to design and test similar upgrades to the Minuteman III missile. CBO assumed that 

the costs of the Peacekeeper modification effort would be 

somewhat more expensive—about $490 million—to account for cost growth.

Mobile Launcher. Under Alternative 6, two mediumrange CAV missiles would be placed aboard one mobile 

launcher. Mobile-launch vehicles are produced today, although CBO assumed that the CAVs and the solid-fuel 

rocket booster would need a newly designed canister to 

provide a stable environment for the missiles and to contain them on the vehicle. On the basis of estimates that 

were developed in CBO’s earlier study on missile defense, 

CBO estimated that it would cost about $280 million to 

develop those canisters.20

Rocket Motor. CBO used a cost estimating relationship 

developed by Tecolote to estimate development costs for 

the rocket motors needed for the space-based alternative.21 That method uses several factors, including the 

duration of the development phase, the number of prototypes built during that phase, and the total procurement 

cost of the rocket motors. CBO estimated that the procurement cost of the rocket motors would total about 

$140 million. (Derivation of that procurement estimate 

is discussed in the subsequent section on procurement.) 

Assuming that the development program for the CAV 

rocket motor would require 16 prototypes and that the 

development phase would last 60 months, CBO estimated that developing the rocket motor would cost about 

$400 million.

Protective Satellite. The protective satellite is the orbital 

support component of the space-based system that includes a propulsion system to control the satellite’s position in orbit and shielding to protect the CAVs from the 

harsh environment in space. CBO used a cost estimating 

relationship derived by Technomics that gauges development costs for the protective satellite on the basis of its 

weight.22 Assuming that the protective satellite would 

weigh about 10,900 pounds, CBO estimated that the development of the protective satellite would cost about 

$610 million. 

Launch Vehicles. CBO assumed that the space-based 

CAVs would be put in orbit aboard rockets that are currently used to launch other military payloads; therefore, 

no additional development costs for those vehicles were 

included in this estimate. 

Testing and Evaluation. For both ground-based alternatives, CBO assumed that DoD would conduct 16 integrated flight tests of the CAV and the launch vehicle over 

a four-year period. On the basis of cost estimates for production of CAVs and launch vehicles, CBO estimated 

that the hardware for those tests would cost almost $200 

million. Additionally, information provided by a contractor indicates that support equipment at the test sight, target sets, and test data processing would cost about $400 

million. After accounting for cost growth of about 40 

percent, CBO estimated that testing and evaluation 

for either ground-based alternative would cost about

$1 billion.

In the flight-test program for the space-based alternative, 

the Air Force would launch two heavy launch vehicles, 

each carrying one satellite and eight CAVs. By CBO’s estimates, the flight-test program would cost about $1.7 

billion—almost double the costs for the ground-based alternatives because of the additional expense of two heavy 

launch vehicles.

System Integration. For all of the alternatives, CBO assumed that system integration would add 20 percent to 

the total costs for common aero vehicles, booster vehicles, 

and mobile launchers—consistent with the costs for existing boosters such as the Minuteman and Peacekeeper 

programs and the estimated costs for the kinetic energy 

interceptor program. System integration would cost 

about $400 million for the ground-based alternatives and 

about $670 million for the space-based alternative, CBO 

estimates.

19. The deployment module provides structural support and carries 

the electronics needed to activate and deploy the CAV, and the 

shroud protects the CAV during flight.

20. Congressional Budget Office, Alternatives for Boost-Phase Missile 

Defense (July 2004).

21. Tecolote Research, Inc., The Unmanned Space Vehicle Cost Model, 

8th ed. (Goleta, Calif.: Tecolote Research, June 2002).

22. Technomics, Inc., National Missile Defense Propulsion Cost Estimating Relationships (Santa Barbara, Calif.: Technomics, August 

2000.)
52 ALTERNATIVES FOR LONG-RANGE GROUND-ATTACK SYSTEMS

Table A-9.

Summary of CBO’s Cost Estimating Methods for Common Aero Vehicles in 

Alternatives 6, 7, and 8

Continued

Procurement Costs

Procurement costs would total between $870 million and 

$1.2 billion for the ground-based alternatives and about 

$7.7 billion for the space-based alternative. CBO 

calculated total procurement costs using a two-step 

approach—first estimating the costs of producing the 

first unit of each of the major components and then projecting those costs for the remaining purchases. CBO assumed that the unit price of subsequent CAVs would not 

decline appreciably because the procurement quantities 

would be small. In CBO’s estimate, procurement costs 

include the cost of producing the CAVs themselves, as 

well as the cost of booster vehicles and mobile launchers 

for the ground-based alternatives and the costs of rocket 

motors, protective satellites, and launch vehicles for the 

space-based alternative.

Common Aero Vehicle. CBO used actual procurement 

costs for the Air Force’s Mk 21 reentry vehicle (developed 

for the Peacekeeper missile) to estimate the procurement 

costs for the CAV in all three alternatives. However, the 

CAV would require more thermal protection than would 

the Mk 21. According to the Air Force, the average cost 

of the Mk 21 reentry vehicle is about $1 million (assuming a purchase of about 50 of them), divided evenly between the cost for the vehicle’s outer shell and the fusing 

and firing assemblies. CBO increased that cost to account 

for several technical differences between the notional 

CAV and the Mk 21 reentry vehicle.

First, CBO increased costs to account for two differences 

in the physical characteristics—the size of the CAV and 

the need for greater thermal protection. The Mk 21’s reentry vehicle has a conical shape that measures about two 

feet wide at its base by about six feet tall. CBO assumed

Research and Development Procurement

Ground-Based Alternatives

Hardware, Material, and Fabrication

Common aero vehicles Costs were estimated using the Air Force’s 

FALCON program with adjustments for 

additional management and cost risk.

Costs were estimated using the Air Force’s 

Mk 21 reentry vehicle with adjustments for 

more insulation, heavier mass, and the 

vehicle’s payload and navigation 

equipment.

Booster vehicles

Medium-range booster An Army cost estimate was used to project 

costs.

A statistical cost estimating relationship 

was used that relates production costs to 

a booster’s impulse.

Peacekeeper Costs were based on those for the 

Minuteman III missile system.

Costs were based on those for the 

Minuteman III missile system.

Mobile launchers An Army cost estimate was used to project 

costs.

Costs were based on a contractor’s 

estimate of the costs for a mobile launcher 

proposed for use with boost-phase

interceptors.

Testing and Evaluation Costs were based on those for hardware 

and data processing for 16 tests.

Not applicable.

Systems Integration A percentage (20 percent) was added to 

the costs of hardware design and testing 

and evaluation activities.

Not applicable.
APPENDIX: THE METHODOLOGY BEHIND THE COST ANALYSIS 53

Table A-9.

Continued

Source: Congressional Budget Office.

Note: FALCON = Force Application and Launch from the Continental United States; EELV = Evolved Expendable Launch Vehicle.

that the CAV would measure three feet by 15 feet and 

would have three to four times more surface area than 

would the Mk 21 reentry vehicle. CBO estimated that 

the difference would increase costs by a factor of 3.4, assuming that costs were proportional to surface area. 

Whereas the Mk 21 follows a ballistic trajectory toward 

the target, the CAV would glide and maneuver toward 

the target after it reentered the atmosphere, subjecting it 

to greater mechanical stresses and higher temperatures for 

a longer period of time. On the basis of information provided by a contractor, CBO estimated that the CAV 

would require about two inches of insulation beneath the 

surface coating used on the Mk 21 reentry vehicles. On 

the basis of discussions with industry analysts, CBO estimated that the price of the insulation would be about 

one-third the cost of the coating. After accounting for 

those physical characteristics and the cost for the surface 

coating and insulating materials, CBO calculated that the 

cost of the thermal protection for the CAV would be 

about 2.6 times more per square foot than the cost of 

thermal protection for the Mk 21 reentry vehicles. After 

increasing the average cost of the Mk 21 shell by both the 

surface area and thickness factors and increasing the average cost of the fusing and firing assemblies by the surface 

area factor only, CBO estimated that those components 

would cost between $4 million and $5 million per CAV. 

Second, CBO increased the costs of the CAV to account 

for an onboard navigation and guidance system. Such systems are components of the Minuteman missile itself; 

thus, their costs are not included in the price of the Mk 

21 reentry vehicle. CBO’s estimate of those costs was 

based on the actual procurement costs of currentgeneration guidance and navigation equipment for the 

Minuteman III missiles. According to budget materials, 

Research and Development Procurement

Space-Based Alternatives

Hardware, Material, and Fabrication

Common aero vehicles Costs were estimated using the Air Force’s 

FALCON program with adjustments for 

additional management and cost risk.

Costs were estimated using the Air Force’s 

Mk 21 reentry vehicle with adjustments for 

more insulation, heavier mass, and the 

vehicle’s payload and navigation 

equipment.

Rocket motors A statistical cost estimating relationship 

was used that relates design costs to 

several factors, including procurement 

costs.

A statistical cost estimating relationship 

was used that relates production costs to 

a rocket motor’s impulse.

Protective satellites A statistical cost estimating relationship 

was used that relates design costs to a 

satellite’s weight.

A statistical cost estimating relationship 

was used that relates production costs to 

a satellite’s weight.

Launch vehicles This cost was assumed to be a sunk 

investment.

Costs were based on those for the Air 

Force’s EELV heavy launch vehicle.

Testing and Evaluation Costs were based on those for hardware 

and data processing for 16 tests.

Not applicable.

Systems Integration A percentage (20 percent) was added to 

the costs of hardware design and test and 

evaluation activities.

Not applicable.
54 ALTERNATIVES FOR LONG-RANGE GROUND-ATTACK SYSTEMS

the most recent purchase of guidance and navigation 

equipment for the Minuteman missile cost between $2 

million and $3 million.

Third, CBO included in the estimate the costs for a 

1,000-pound warhead that would be deployed on the 

CAV. CBO’s estimate of about $6,000 per warhead is 

based on the average cost for such devices according to 

the Air Force’s budget materials. 

Finally, CBO increased costs to account for historical cost 

growth for comparable systems. On the basis of a report 

by RAND, CBO estimated that production costs for the 

CAV could grow by 38 percent.23 Thus, CBO estimated 

that the average cost of the CAV would total about $11 

million. For the two ground-based alternatives, CBO estimated that it would cost about $540 million to buy 48 

CAVs. That estimate includes the cost to integrate the 

CAV with the other components of the weapon system—

about 12 percent of hardware costs based on experience 

with other comparable programs. For the space-based alternative, CBO assumed that DoD would buy a total of 

128 CAVs at a cost of $1.4 billion.

Booster Vehicle. In Alternative 6, CBO assumed that 

each solid rocket booster would carry a single CAV and 

that two boosters would be loaded on each mobile 

launcher. On the basis of a cost estimating relationship 

that relates booster thrust to cost, CBO estimated that 

each booster would cost about $9 million, including 

about $1 million for the canister to contain the booster 

on the mobile launcher. That estimate also includes a factor of about 38 percent for cost growth. In total, CBO estimated that buying 48 boosters would cost about $420 

million.

In Alternative 7, the Air Force would deploy the CAVs 

aboard Peacekeeper missiles. CBO estimated that each 

Peacekeeper missile would be able to carry two CAVs; 

therefore, a total of 24 missiles would need to be modified—20 for operations and four for spares. (On the basis 

of information from the Air Force, CBO estimated that 

there are about 60 Peacekeeper missiles in the U.S. inventory.) CBO assumed that the modifications would include upgrading the missile’s propulsion and guidance 

system, buying a new deployment module, and buying a 

new shroud. As a point of comparison, actual costs for 

upgrading the propulsion and guidance system for the 

Minuteman III missile averaged about $6 million per 

missile. Assuming that the costs for upgrading the Peacekeeper missiles’ propulsion and guidance system would 

be comparable with those costs, and adding $4 million 

for the costs to procure a new deployment module and a 

new shroud, CBO estimated that the costs to modify 

each Peacekeeper missile would total about $14 million. 

That estimate includes a cost-growth factor of 38 percent. 

In total, CBO estimated that modifying 24 Peacekeeper 

missiles would cost about $330 million.

Mobile Launcher. In Alternative 6, the CAVs would be 

placed aboard a mobile launcher that would carry two 

medium-range CAV missiles. For this analysis, CBO used 

a cost estimate that was developed in an earlier study on 

boost-phase interceptors.24 In that study, CBO estimated 

that a mobile launcher capable of firing two interceptors 

would cost a little more than $11 million in 2004 dollars. 

After adjusting for inflation, CBO estimated that each 

mobile launcher would cost slightly less than $12 million 

in 2006 dollars, or about $280 million for 24 mobile 

launchers.

Rocket Motor. In Alternative 8, the space-based CAVs 

would use a rocket motor to reenter the Earth’s atmosphere. CBO applied a cost estimating relationship developed by Technomics that relates a rocket motor’s procurement costs to the product of its total impulse expressed in 

newtons of thrust and its burn time expressed in seconds. 

CBO estimated that a rocket motor with a thrust of 113 

kilo newtons and a burn time of five seconds would cost 

just over $1 million to produce.25 That estimate also includes a factor of 19 percent to account for growth observed in the cost estimates of comparable space-based 

systems.

CBO assumed that the rocket motors would be bought 

over the same time period as would the CAVs and that 

the cost per rocket motor would remain essentially unchanged over the production period. Buying 128 rocket 

23. Jeanne M. Jarvaise, Jeffrey A. Drezner, and Daniel M. Norton, 

The Defense System Cost Performance Database: Cost Growth Analysis Using Selected Acquisition Reports, MR-625-OSD (Santa Monica, Calif.: RAND, 1996). 

24. Congressional Budget Office, Alternatives for Boost-Phase Missile 

Defense.

25. Technomics, Inc., National Missile Defense Propulsion Cost Estimating Relationships. 
APPENDIX: THE METHODOLOGY BEHIND THE COST ANALYSIS 55

motors (one for each of the CAVs) would cost a total of 

about $140 million, CBO estimates. 

Protective Satellite. CBO applied a cost estimating relationship developed by Tecolote that uses the weight of 

the protective satellite to estimate the cost to procure the 

protective satellite. CBO assumed that the protective satellite would weigh about half as much as the combined 

weight of the eight CAVs. Eight CAVs and their rocket 

motors would weigh about 21,800 pounds; therefore, the 

protective satellite would weigh about 10,900 pounds. 

CBO estimated that each protective satellite would cost 

about $45 million. 

CBO assumed that the protective satellites would be 

bought over the same time period as would the CAVs and 

rocket motors. Buying the 16 protective satellites (one for 

every eight CAVs) would cost about $720 million, CBO 

estimates. 

Launch Vehicle. The space-based CAV system would be 

put in orbit by a launch vehicle. CBO estimated that each 

satellite—consisting of one protective satellite and eight 

CAVs—would weigh about 16 tons. CBO assumed that 

the CAV system would be launched aboard a heavy 

launch vehicle currently planned for the Air Force’s EELV 

program and assumed that DoD would place one CAV 

satellite aboard each launch vehicle. CBO estimated the 

procurement costs for the launch vehicle on the basis of 

budget data provided by the Air Force. Those data indicate that the costs for a launch vehicle would total about 

$340 million, including about $190 million for the vehicle hardware and about $150 million for the launch services. CBO estimated that the costs for 16 launch vehicles—one CAV satellite on each heavy launch vehicle—

would total about $5.4 billion.

Military Construction Costs

Under Alternative 7, CBO assumed that the Air Force 

would make improvements to facilities at Cape Canaveral 

Air Station and Vandenberg Air Force Base, the bases 

where the Peacekeeper/CAV systems would be deployed. 

At each base, the Air Force would install new equipment 

to support ground operations and build 10 new silos to 

house the Peacekeeper missiles. Support equipment 

would cost about $50 million per set, and the missile silos 

would cost about $15 million each. After applying a factor of 50 percent to account for cost growth, CBO estimated that it would cost $600 million for silos and support equipment at the two bases. 




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