## Transforma tive Aircraft

and Green Flight Challenge II

ABSTRACT

The aeronautical, environmental and societal benefits of the transformation to Green aviation are described along with the urgencies that compel it. A proposal is presented to bring abou t these benefits by extending NASA’s Centennial Challenge for Aeronautics. Performance goals are set for future Green, Quiet, V/ E STOL aircraft that can transform transportation.



### ABBREVIATIONS:

CAFE: The Comparative Aircraft Flight Efficiency Foundatio n C.A.F.E.: Corporate Average Fuel Economy, the U.S. MPG standard for cars CTOL: Conventional take

- off and landing DOD: Department of Defense DOT 500: Dept. of Transportation Federal Motor Vehicle Safety Standard No. 500 (49 CFR 571.500), for slow speed 4 wheel residential vehicles of ≤ 25 mph. DtD: “Door

- to

- door”, referring to a trip’s complete path G: The acceleration due to gravity GA: General aviation GFC: Green Flight Challenge, NASA’s Centennial Challenge for aeronautics GFC I: The CAFE Green Flight Challenge of 2011, fore GQ CTOL aircraft GFC II: A proposed GFC for GQ V/STOL aircraft GQ: Green and quiet, as applied to aircraft with those attributes Green: Environmentally

- friendly in terms of emissions and energy use IC: Internal combustion, referring to engines pMPG: Passenger miles per gallon, i.e., vehicle MPG x # of seats RC: Radio

- controlled, as in hobbyists’ models SF: San Francisco, California STOL: Short take

- off and landing TSA: Transportation Security Administration UCSF: University of California at San Francisco U.S.: United States of America Vc: Cruise velocity VMT: Vehicle miles traveled VTOL: Vertical take

- off and landing V/STOL: Either vertical or short take

- off and landing2



## Transformative Aircraft
and Green Flight Challenge II by Brien A. Seeley M.D., Presid ent, CAFE Foundation
May 17 , 2009



### INTRODUCTION
The most basic purpose of aviation is to travel fast without need of roads. Yet, after America’s first Century of Flight, our hub and spoke air transportation system fails to fulfill that purpose for the very trips that people most often make

-- trips of less than 200 miles. By converging current technologies, w e can remedy this failure by drastically reducing the distance between airport and destination doorstep. In our current built environment, the only feasi ble way to effect this transformation is by bringing forth a new class of Green, Quiet V/ESTOL aircraft

— the “GQ aircraft”.

NASA articulated the vision of this transformation in 2003. 1,2 

### Due to the continued worsening of surface gridlock, along with global warming and the need for Green, that vision has become even more urgent and compelling today. Since the first

ever CAFE Electric Aircraft Symposium in 2007, it has become clear that the missing ingredient necessary for this transformation, i.e., ultra

- quie t operation, is finally within reach thanks to electric propulsion.

NASA’s current quest to make aviation Green and Quiet, the 2011 CAFE Green Flight Challenge (GFC), is an important first step in the transformation to a future of sustainable mobility free dom. To maximize the benefits of the GFC, a follow

on “GFC II” needs to be created. Like the inaugural GFC, GFC II should demand GQ aircraft. But for GFC II, the aircraft must also have vertical or extremely short take

- off and landing capability (V/ E STOL). These are the only type of aircraft that will have both the capability and the consent to land at “pocket airports” , very close to destination, eliminating the onerous delays of surface gridlock. This, along with enhanced computerized flight decks that ma ke them safe and easy to fly, is what will make them useful and popular. The popularization of GQ V/ E STOL aircraft can revitalize aviation, transform our transportation system and bring many other societal benefits. Harnessing the3



### resource of talented citi zen innovators and universities to bring forth such aircraft would be the most practical, efficient and valuable of any NASA Challenge. Ironically, after aviation has conquered the sound barrier and soared high above the stratosphere, its most promising ne w frontier turns out to be that of mastering the ability to fly slowly, quietly, safely over our own backyards , like birds.



### NASA GOES GREEN
Fortunately, on July 31, 2009, visionary leaders at NASA launched a technology prize squarely aimed at Greening avi ation. It is the 2011 CAFE Green Flight Challenge (GFC), the largest monetary prize ever offered in aviation. Aviation’s lack of Greenness has not been a concern of military aviation. It needed a civilian solution. No single entity, program, funding or lea dership had emerged to make aviation Green, until now. NASA’s GFC will provide both the means and the opportunity to make it happen. In summer, 2011, NASA will award $1.5M cash to the highest scoring “Prius of the Sky”. These will be aircraft that are Gree n and Quiet

— GQ aircraft.
The GQ aircraft in the GFC must demonstrate 100+ mph while achieving at least 200 passenger MPG. They must take off over a 50 foot obstacle in less than 2000 feet while emitting no more than 78 dBA, as measured 250 feet to the side of the runway. They must be capable of maintaining level flight at or below 52 mph.

Indications are that the GFC

- winning aircraft will sensationally surpass the 100 mph/200 pMPG threshold by combining the best of today’s technology. That achievement will attract consumers as well as global media attention. But this inaugural GFC

— GFC I

— is just the beginning of the needed Green transformation of aviation.
Imagine the GFC I

- winning “Prius of the Sky” becoming able to take off and land within walking distance of nearly any destination, immune to surface gridlock. This is the ideal goal for GFC II

— quiet, fast Green Flight with vertical or extremely short take

- off and landing (V/ E STOL) capability. V/ E STOL capability can be defined as being able to take off or lan d over a 50 foot obstacle in no more than 4 00 feet. Achieving V/ E STOL w ith little or no reduction in cruise velocity (Vc), quietness or “Greenness” is an unprecedented challenge. It would produce a truly game

- changing aircraft.
GFC I, in keeping with NASA ’s mission, is designed to advance aviation for the benefit of all. GFC II would further leverage the se benefits. It would build upon GFC I’s media attention and could extend and solidify the value of its name sponsor’s “Green branding”. The top GFC I airc raft could return with E STOL modifications to compete against totally new GFC II V/ E STOL designs to rapidly bring forth the best possible combined performance. This mix would advance several technologies concurrently:

• High

- lift devices, long overdue in GA

• Circulation control4

• Inflatable Coanda flow guides

• Multi

- deployable fabric lift surfaces

• Morphing wings

• Channel

- wing technology

• Electric motors with tilt

- rotor capability

• Vectored thrust technology

• Powered lift

• Quiet propellers and ducted fans

• Goldschmied p ropulsion

• Alternative and hybrid energy sources

• High Power density of both motors and batteries

• Distributed propulsion

• Motor

- in

- wheel propulsion and braking

• Computerized stability and low

- speed control

• V/STOL safety and reliability

• Nano

- materials

• Drag redu ction
Aircraft that combined the aeronautical advances demanded by such a challenge could not only revitalize aviation, they could transform our transportation system and bring many other societal benefits. This is a lofty goal that is powerfully Green in several ways that will be explained below.
This goal wou ld be best achieved by setting required performance thresholds and then rewarding the GFC II competitor that surpasses them by the largest margin. This “Best of Breed” approach increases participation compared to a “First

- to

- Demonstrate” format. A Best of Breed competition is more attractive to the media and hence more valuable to its sponsor. It can be repeated to win further incremental gains, if desired.



### WHY V/ E STOL IS NOT ENOUGH

The game

- changing new GQ V/ E STOL aircraft must overcome the deficiencies that have prevented existing V/ E STOL aircraft from becoming popular. These deficiencies are:5

• Unacceptably high cost

• Poor fuel economy, i.e., NOT Green

• High noise emissions

• Safety concerns

• Poor reliabil ity

• H igh maintenance

• Low cruise speeds

• Resentment of perceived privilege

• The obstacle of flight training

• Lack of time savings
The new breed of GQ V/ E STOL aircraft must correspondingly be very quiet, Green, ultra

- efficient, accessible to most people and aff ordable. They must offer trip speeds that are substantially better than cars and must be easy to learn to fly. Their safety and runway requirements must be “neighborhood

- compatible” for them to gain the crucially important close

- in access to destinations. Global warming, peak

- oil and our dependence upon foreign oil w ill increasingly demand that such future vehicles be Green.
This combination of vehicle capabilities are achievable with today’s technology. Howev er, creating GQ V/ E STOL aircraft is beyond the m eans and market risk of small aircraft manufacturers. It is a highly challenging, breakthrough achievement that is ideal for a substantial, well

- focused technology prize.
“Neighborhood

- compatible” runway requirements mean E STOL aircraft that can ope rate fr om airstrips that are ≤ 4 00

- feet long, and VTOL aircraft that require less than 100

- foot diameter landing sites. Mainly because of noise issues, small diameter VTOL landing sites have often been forbidden in residential areas. Due to local opposition, down town San Francisco now has no active helipads. It has a few unused and former rooftop helipads that can only be used in emergencies. 3
The opposition to VTOL landing sites means that, until VTOLs become much quieter, E STOL and VTOL landing sites will contin ue to generally coincide and thus share equal proximity to destination. In addition, clearing a 50’ obstacle at 250’ and landing on a 100’ pad is essentially how helicopters operate today in order to stay out of the “dead

man’s zone” of engine failure. Acc ordingly, in the near

- term future, it follows that VTOL capability be should accorded only slightly greater GFC II scoring value than E STOL capability. See Graph III.



### SMALL HYBRID V/ E STOLs6

GQ V/ E STOL aircraft must be very lightweight and efficient. They m ust move a large mass of air downward at velocities that do not produce much noise. These demands for low thrust loading and light weight favor small, 1

- 2 seat electric

- powered aircraft with transient high power density for take

- off and low continuous powe r use during cruise flight. Since ground commuter vehicles typically carry only 1.3 persons, a 1

- 2 seat aircraft can offer significant utility. Because of their suitability as “air taxis”, heavier 4

- 6 seat V/ E STOL aircraft should be encouraged as well. The se might deserve some allowance for greater noise due to the greater power needed for their increased gross weight.
As DOD’s study has recently found 4 , the quest for speed and being constrained to low thrust loading to limit noise means that future V/ E STOL aircraft are likely to need to employ a hybrid design of fixed

- wing plus some rotor lift. See Appendix. Such hybrids need a short runway rather than a helipad. The hybrid’s fixed wing is needed to smoothly accelerate a large mass of air downward at a rela tively low velocity, i.e., quietly, and its forward speed on the short runway provides the dynamic pressure necessary to move that air mass. Ideally, that short runway can be built on a very small land parcel, such as 2 acres. Such a 2

- acre “pocket airpor t” could provide a short runway that is 418 feet long, along with several spaces for aircraft parking.
To use very short runways, aircraft must be able to accelerate quickly during take

- off and then climb out at a steep angle. They must be capable of contr olled flight during a slow

speed, steep glideslope on final approach to landing. To use a pocket airport, the landing touchdown must be precise without overshoot or undershoot. The hybrid of fixed

- wing plus rotor , using wing spoilers, can achieve such perf ormance. Small, unoccupied, RC models have demonstrated this 5 . Full

- scale versions of such hybrids would almost certainly require computer

- aided stability and control in order to handle strong gusts and crosswinds that can rival dynamic pressure in magnitu de. Such computer

- aided control would give a valuable head

- start toward precise, autonomous flight for these vehicles, another feature that they will need in order to become popular.
Electric motors are favored in GQ V/ E STOL hybrid aircraft because of thei r high

efficiency, high reliability, high power to weight ratios, smooth running (more suitable for tilt

- rotor), quiet, emission

- free power and installation simplicity compared to internal combustion (IC) engines. However, the IC engine, if it can be quiet and Green enough, offers a clear advantage in range, re

- fueling time and extant support infrastructure.



### “SPEED IS WHAT SELLS AIRPLANES”

— Roy LoPresti

Time is a non

- renewable resource. For members of the multi

- tasking “X Generation” and “Texting Ge neration” time is likely to be the scarcest commodity in the 21 st Century. Busy people tend to exhibit a disproportionate hunger for speed in their choice of vehicle. In order to attract a mass market, GQ V/ E STOL aircraft must provide DtD trip speeds that are at least twice that of any other form of transportation, and the faster the better. To7

accomplish this, V/ E STOL aircraft will need cruise speeds of over 100 mph on trips of under 100 miles and speeds of near 150 mph on trips of under 200 miles. See Gra ph II. Accordingly, GFC II must reward Cruise Velocity (Vc) as one of its key metrics, with the other scoring metric being Take

- off Distance. See Graph III. The high speeds demanded in GFC II will demand aircraft with minimal drag and this may be more achi evable in hybrid fixed

- wing/rotor GQ V/ E STOL aircraft than in traditional VTOL rotor

- craft.
The unavoidably long delays of single file surface travel to and from conventional airports by car or bus make the speed and range of CTOL aircraft almost irrelevan t for the trips most people want to make

— trips of 200 miles or less. These ground travel delays are now endemic in our built environment and, along with other factors, have severely depressed the market for CTOL aircraft today. With all due respect to the great Roy LoPresti, we must recognize that in the 21 st Century, it will be the DtD trip speed that sells airplanes.
The only feasible way to enhance DtD trip speed is for aircraft to become fast, GQ V/ E STOLs and the best way to bring that about will be wit h a technology prize.



### WHAT ABOUT FLYING CARS?
For decades, the dream of the flying car has attracted interest and yet failed to win a market. The criticism usually leveled has been that flying cars have been mediocre cars and mediocre aircraft. Sadly, jus t when technology might enable a CTOL flying car to achieve satisfactory flight performance, the worsening gridlock that reigns between CTOL airport and destination robs its value as a time

- saver. Ultimately, the flying car needs to become a GQ V/ E STOL air craft and that could be the basis for a follow

- on challenge to the GFC II. However, becoming Green, Quiet and V/ E STOL imposes very difficult demands upon a self

- contained flying car that is already burdened with the weight and performance penalties that at tend automotive use. The GQ V/ E STOL function is what counts most because the “last mile connectivity” for such aircraft can be achieved by walking, bicycle, golf cart, etc. rather than by car. Compromising the GQ V/ E STOL aircraft’s performance in order for it to become a flying car is probably not necessary and should not be the primary technology goal.



### WHY NOT ANOTHER CTOL PRIZE?
High fuel costs, high prices for new certificated aircraft, a global recession and increasing airspace/TSA restrictions have al l added to the depressed market for CTOL aircraft. Cessna, Cirrus, Beech and Mooney have laid off thousands of workers. General aviation (GA) flight operations are down nearly 50% compared to the 1990s and there are nearly 50% fewer student pilots today th an in the 1980s. The GA market is nearly moribund.
A report by Thomas Frank in USA Today on September 17, 2009, entitled “Feds keep little

- used airports in business” cited the large expenditures being made with tax funding to support under

- utilized GA airp orts. GA advocacy groups had to defend our small8

airports against Frank’s attack, which in effect argued that such airports were no longer needed.
To make matters worse, the public has recently expressed outrage at the use of private jets by CEOs of large companies that received government rescue funding. These jets are resented by the public as symbolic of a non

- Green, privileged excess of luxury, expense and pollution. The public’s sense of fairness expects everyone should have to suffer the grind of grid lock like they do. If fast travel by air were affordably available to the public, their resentment would likely subside.
In the last 5 years, the emergence of CTOL Light Sport Aircraft (LSAs) and Very Light Jets (VLJs) have both failed to produce the hoped

- for transformation of aviation. Despite expensive advertising hype for beautiful new small jets and innovative new LSAs, the sales of these aircraft number in the dozens instead of in the thousands. No matter how glitzy, these aircraft will never be able to avoid the time wasted on ground travel to and from CTOL airports.
The adverse environmental footprint of CTOL aviation today is unsustainable. Its inefficient land

- use, poor proximity to destination, toxic fuels, lack of pollution controls, high noise e missions, vulnerability to terrorism and poor fuel efficiency all need to be remedied. The remedies need to come soon in order to avert loss of our CTOL airports.



### SURFACE GRIDLOCK : BOUND TO GET WORSE
Experts predict that ground travel delays due to surfac e gridlock will get substantially worse in the next 20 years. Door

- to

- door trip speeds in the Los Angeles Basin, for example, are predicted to be just 22 mph in the next 10 years. 1,9 This worsening is adverse to air travel because large CTOL and air carrie r airports are usually relegated to locations several miles outside metro or town centers. This forces most air travelers to suffer the delays of gridlocked commuter highways to reach their destinations.
The trend to gridlock appears inexorable. The growth in surface vehicles and VMT outstrips the growth in population (See Figure 2.5). Planners find that the public is very resistant to giving up the privacy, security, autonomy and personal space of their cars. Even when cars become electric vehicles, the gr idlock will remain.
The public resists using public transit. Buses and trains are inherently constrained to the limitations of two

- dimensional, single

- file surface travel. People deem the waiting, transfer maze, delays and limited distribution of transit s tations to be unacceptably daunting.9



### Figure 2.5, above 6



### .10

These factors cast doubt on the likelihood that public transit solutions to gridlock will succeed. Indeed, public transit ridership is declining. A study by the Madison Institute of the f uture impact of high speed rail on reducing road use has made a similar, pessimistic forecast. 7 See Figure 2.7 below.



### Figure 2.7, above

Unlike surface transportation, flying can provide highways in the sky with unlimited numbers of lanes and overpasses , off

- ramps and merges. A highway in the sky can be reconfigured instantly and does not require public purchase of expensive land that must be permanently removed from open

- space or any other use. Unlike paving with asphalt, building aeronautical highways does not require millions of barrels of crude oil.11



### IF WE BUILD IT, THEY WILL COME
The transformation of aviation enabled by GQ V/ E STOL aircraft is predicated upon the concept of “pocket airports”, affordable 2

- 4 acre parcels that can be situated within 2 or 3 miles from one’s destination doorstep.



### Figure 2.9, above
Pocket airports are designed exclusively for GQ V/ E STOL aircraft and will be built only after such future aircraft are created, proven safe and popularized. The popularization of GQ V/ E STOL a ircraft will most likely begin with air taxi services demonstrating their great utility. Later, as flight deck automation and NextGen air traffic control matures and makes flying easier, large numbers of non

- professional pilots will personally adopt

owners hip and routine use of GQ V/ E STOL aircraft.
As shown in Figure 2.9, above, the pocket airport is only slightly larger than a football playing field. The 236 foot ground roll shown would give a 0.2 G deceleration to full stop from a touchdown speed of 38 mp h. That ground roll would require a 15° glide

- slope in order to clear a 50 foot obstacle situated at the end of the runway.
The pocket airport is analogous to the “pocket park” concept of new urbanism, where several small, walk

- accessible neighborhood park s save having to drive to a more distant regional park. Pocket airports are likely to initially be built as exclusive new residential airparks and business campus amenities. These will prove the value of the concept. Once12

proven, these can sprout within wa lking distance of town centers. They will become the beacons of their neighborhoods, from which one could imagine “from here, I could go anywhere”.
Such opportunity will help regional cities to preserve their urban growth boundaries by encouraging infill d evelopment and the sprouting of new, self

- sufficient exurbs with greater reach. Pocket airports will also invite Green surface transportation such as low

speed, DOT 500

- compliant electric vehicles, co

- located mass transit stations, rentab le bicycles as wel l as walking. 8 , 10
Walking and its cousin, bicycling, epitomize “Green”. They afford transportation, healthful exercise, and enjoyment while conserving fossil fuels, reducing toxic waste outputs, improving mind

- body connection and physical vitality, and en gaging people more fully in the experience of places. While human

- powered travel modes are much slower than motorized travel, they are much more energy efficient, and their social, health, and especially environmental benefits make them now

- more than eve r

– major Green.
Pocket airports not only would solve the problem of “ground leg connectivity” in air transportation, they could be reached by walking. Walkable communities can address many of the nation's greatest current public health concerns, includin g obesity, cardiovascular disease, diabetes, asthma, injury, depression, road rage, violence and social inequities. Walkability to bus/train transit, airport, market, shopping and job needs to become a priority. Land costs, existing development, tight gove rnment budgets, limited open space and underutilization preclude building more large airports for conventional take

- off and landing aircraft (CTOL). But 2

- acre parcels can be found within 2 miles of most town centers where pocket airports could be affordab ly built.
In the built environment of major metropolitan cities such as New York, Chicago, San Francisco and others, pocket airports could be implemented on large barges in the nearby bodies of water. This concept obviously will demand that the GQ V/ E STOL aircraft be extremely reliable and capable of precise spot landings.

In San Francisco, as shown in Figure 3 below, the several sites at which pocket airports could be built would provide excellent walkable access to the city’s major attractions.13



### Figure 3

. 10 Potential Pocket Airports in San Francisco

1. Crissy Field, Exploratorium, Presidio 6. Fillmore, Western Addition

2. Ghirardelli Square, Fisherman’s Wharf 7. Kezar Stadium, UCSF Med Center

3. Ferry Building, Financial District 8. Sloat Blvd, SF Zoo

4. SF Giants Stadium, China Basin 9. Ocean Beach, Cliff House

5. Cesar Chavez Street Wharf, Shipyard 10. Baker Beach
Note that most destinations on the above map of San Francisco lie within just 1 mile of a potential pocket airport and virtually no poin t lies more than 3 miles from a potential pocket airport.
Converting communities to pocket airports will in itself be powerfully Green. Eliminating nearly 2 hours and 60 miles of surface travel to metro airports, often involving fuel

wasting gridlock, coul d spare the need for more lanes on highways. It has been reported that in one year, Americans wasted 2.9 Billion gallons of gasoline while stuck in gridlock 11 , much of it in metro areas near large hub airports. The rate of increase in the number of cars ou tpaces our ability to build more lanes onto highways. (See Figure 2.5,14

below). The value of the time wasted in traffic is incalculable but enormous. Pocket airports can improve all of the above.
High energy efficiency and emission

- free or bio

- fueled aircra ft will reduce carbon emissions a great deal. Distributed air travel, i.e., flying ‘as the crow flies’, shaves about 10% off of the trip miles a car or mass transit would entail. These aspects of Greenness are independent of the actual MPG of the aircraft and some might say that fact justifies allowing GQ V/ E STOL aircraft to achieve less than the 200 pMPG demanded by GFC I.
Pocket airports offer a degree of immunity to terrorism, a redundancy for airborne disaster relief and a more distributed system for Med

- evac air ambulance. They are an ideal fit with Peter Calthorpe’s 12 new urbanism and its “transit

- oriented development”. The future of transportation is not more single file surface byways. It is not more cars or more lanes on the freeway.



### SOCIETAL BENE FITS
Transforming our transportation system will produce many societal benefits, including growth in airspace capacity, mobility, safety, Green technology, jobs and manufacturing, along with inspiration for our next generation of young scientists, engineer s and technology leaders. Pocket airports can make us more energy independent and that means both our nation and others become more self

- sufficient. GQ V/ E STOL aircraft are unprecedented and could open a new market whose potential was predicted to approach $1 trillion 2 . These benefits align with our nation’s goals and NASA’s mission.
Landing site cost tends to be proportional to the square of the runway length. An airport with 5000 foot runways, though 10 times longer than one with 500 foot runways, can co st 100 times more. It is reported that in one year, 1995, the U.S. spent $95 billion on road building. Reducing the cost of road

- building is a societal benefit that could enormously reduces the use of and dependency on fossil fuels. In 2004, NASA Chief Sci entist Dennis Bushnell 2 cited Arthur Clarke’s 1984 quote that “The roads to support Autos cost as much as a small War and the casualties are on the same scale” as a reason to support future personal air travel. In that same presentation, he pointed to Will iam Seifert’s 1968 prediction that “ Any form of transportation that offers the lowest door

- to

- door travel time will always drive out lower speed competing modes unless the economics of the higher speed system are grossly unfavorable”

. V/ E STOL capability tr anslates into safe aircraft that can land at slower speeds in smaller spaces in the event of loss of power. This means lower impact forces that should result in fewer fatalities and less property damage from off

- airport landings. These benefits may lead to better consumer acceptance of these vehicles.



### V/STOL BEATS CTOL
Graph I: (below) The Time Savings of V/STOL15

Graph I shows the surprisingly large amount of time that can be saved by E STOL/VTOL vehicles. The “ground travel time” is based upon the number of miles out to the airport from one’s destination doorstep. Note that STOL/VTOL is the only aviation modality with substantial time savings relative to car travel on trips of less than 200 miles.

-4 -2 0 2 4 6 8

0 100 200 300 400 500 600Time Saved Relative to Car, in hours

Trip Length, miles Airliner 550 mph CTOL 200 mph STOL/VTOL 100 mph STOL/VTOL 150 mph STOL/VTOL 200 mph Car 30 or 60 mph

NOTES: Car in urban use @ 30 mph Car in rural use @ 60 mph Neglecting time spent on pre-flight, taxiing and car rental desk. Includes 45 minutes for airliner park ’n fly plus baggage and security check in.

Assumptions: 30 miles to CTOL or airliner airports 3 miles to STOL airport 0.3 miles to VTOL heli-pad 30 mph car to/from CTOL 18 mph golf-cart to/from STOL port 3 mph walk to/from VTOL heli-pad

Time saved with STOL/VTOL at 150 mph surpasses all other modalities on trips from 50 to 500 miles

The time savings depicted in Graph I varies from typical c onventional large airports (airliners and general aviation’s conventional take

- off and landing (CTOL), 30 miles out) to future STOL airstrips (< 3 miles out) to VTOL landing pads that are < 0.3 miles out from destination doorstep. Assuming a 30 mph car for CTOL, an 18 mph golf cart for STOL and walking at 3 mph for VTOL, the ground travel times will be 60 minutes for CTOL and 6 minutes for both STOL and VTOL.
In Graphs I and II, the ground travel times are doubled to account for the bidirectional travel to/ from the airports involved in any trip by air. This gives ground travel time of 2:45 hours for airliners, 2 hours for CTOL and 12 minutes each for STOL and VTOL. The additional 45 minutes is added for commercial airliner travel is due to baggage

- check and shoes

- off security check

- in.16

The Graphs show that, for trip lengths ranging from 40 to 300+ miles, fast V/ E STOL aircraft offer significant time savings over both cars and conventional air travel. That range will be increasingly important as the public curt ails its VMT to meet the needs of climate change and rising energy costs.
Graph II: (below) The Speed Advantage of V/ E STOL. Note that V/ E STOL is the only aviation modality that achieves significantly faster travel than a car on trips of less than 200 miles . The fast, 200 mph V/STOL aircraft is unrivaled in trip speed until trip length is more than 500 miles. And 90% of all single and twin engine GA flights today are of under 500 miles.

0 20 40 60 80 100 120 140 160 180 200

0 50 100 150 200 250 300 350 400 450 500Door-to-Door Trip Speed, mph

Range, statute miles Airliner 550 mph CTOL 200 mph STOL/VTOL 100 mph STOL/VTOL 150 mph STOL/VTOL 200 mph Car 30 or 60 mph

NOTES: Car in urban use @ 30 mph Car in rural use @ 60 mph Neglecting time spent on pre-flight, taxiing and car rental desk. Includes 45 minutes for airliner park ’n fly plus baggage and security check in.

Assumptions: 30 miles to CTOL or airliner airports 3 miles to STOL airport 0.3 miles to VTOL heli-pad 30 mph car to/from CTOL 18 mph golf-cart to/from STOL port 3 mph walk to/from VTOL heli-pad STOL/VTOL Speed Advantage

Graph III: (below) A potential GFC II Scoring Formula

The formula for the simultaneous optimization of Speed and Take

- off Distance needs to appropriately reward performance that is of practical value. Shortening the Take

- off Distance to less than 100 feet offers very little practical advantage. Likewise, aircraft whose Take

- off Distance exceeds 418 feet forfeit the benefit of pocket airports. A vertical double

- tipped arrow marks the 418 foot take

- off scores. These formula attributes are demonstrated in the Graph III below. Note that all of these aircraft are required to achie ve a very high passenger

- MPG in17

order to qualify for GFC II, and this will m ake speeds above 160 mph very difficult to achieve.

0 50 100 150 200 250 300

0 100 200 300 400 500 600 700 800 9001000Score

Takeoff Distance (TD) over a 50 foot obstacle, feet Vc = 100 mph Vc = 120 mph Vc = 140 mph Vc = 160 mph Vc = 180 mph Vc = 200 mph Vc = 250 mph Vc = 300 mph

1/((0.001*((TD/Vc)^3))+(1/Vc)) Lines of constant Vc

Notes: Helipads are 50-100 ft diam. Soccer fields are 350-400 ft long

STOL equivalent scores: 200 mph/900 feet 160 mph/700 feet 120 mph/500 feet 100 mph/400 feet GFC II Proposed Scoring Formula: Score rewards Cruise Speed (Vc) and Takeoff Distance (TD)

VTOL equivalent scores: 250 mph/400 feet 200 mph/300 feet 160 mph/200 feet 125 mph/100 feet 120 mph/50 feet



### V/STOL IS VERY HIGH TECH

E STOL capability exacts a high price in the form of drag due to large wing area or, alternatively, th e cost and weight penalty that accompanies having complex high lift devices embedded in the wing. VTOL capability has similar penalties in terms of potentially high noise and weight from its high power requirements. Today, advances in drag reduction, motor s, batteries, actuators, high lift technologies, thrust vectoring, computerized stability and control and nano

- material composites make the challenge of V/ E STOL more feasible. The suitability of smooth, power

- dense, reversible electric motors available tod ay for vectored thrust is particularly promising: See: http://www.youtube.com/watch?v=iyTKwTx_VdQ18



### GFC II REQUIREMENTS
GFC II can remove the 52 mph stall requirement of the 2011 GFC I. It still must impose the 100 mph performance threshold and demand a high level of passenger MPG in order to rival future cars. Since 35.5 MPG for ostensibly 4 seat cars is the newest automotive U.S. C.A.F.E. Fleet Goal for 2016, GFC II could demand that all aircraf t achieve at least 142 passenger MPG (4 x 35.5). Ideally, GFC II should require that all entrants achieve a take

- off distance over a 50 foo t obstacle of ≤ 1000 feet. This would be just half of the 2000 foot take

- off required in GFC I and could allow some GFC I aircraft to compete.
If desired, the GFC II take

- off distance requirement could be more stringent, shortened to just 418 feet to fit t he pocket airport. This would likely decrease participation and diversity in the competition and might demand a longer lead time and larger prize purse.

The CAFE Foundation can measure Take

- off Distance accurately and considers it a reasonably valid indica tor of whether an aircraft can fulfill V/ E STOL requirements. Demonstrating and measuring Landing Distance is much more difficult and is not necessary for GFC II. The particular technologies necessary to shorten landing distance and make landings ultra

- prec ise and automatic may be worthy as the subject of a future challenge. That future challenge could further enhance the GQ V/ E STOL aircraft from GFC II.
Winning GFC II will be more challenging, more expensive and more transformative than winning GFC I. Conse quently, the cash prize for GFC II should be at least $2 M. This size of award along with its “Best of Breed” format (as contrasted with “First to Demonstrate”) incentivizes participation by a large number of teams, both private and from universities. In Be st of Breed, all teams will get their chance to demonstrate, rather than becoming abortive efforts after a “First

- to

- Demonstrate” wins all. This increases the leverage and yield of the prize money invested as well as the diversity of innovations. History t eaches us that in technology prizes it is often the aspiring “amateur”, non

corporate teams that make the most passionate and innovative efforts to win.
To maximize the benefits of GFC II, it should be formulated and announced as soon as possible. By conti nuing the name Green Flight Challenge, GFC II will increase the likelihood of major sponsorship support for both events, a key factor in their success. The lead time for GFC II should be at least 2

- 3 years in order to enable both GFC I and GFC II teams mor e time to modify, design and build ideal GQ V/ E STOL aircraft.



### OTHER AERONAUTICAL CHALLENGES
The next aeronautical challenge should be for Green Quiet V/STOL aircraft. Other potential aeronautical technology prizes that aim to demonstrate autonomous flight , auto

landing capability, longer range, faster refueling or recharging or quieter operation, while adding value, are not as important as first bringing forth GQ V/ E STOL aircraft. Autonomous flight and auto

- landing already exist. Longer range (> 200 miles) for19

affordable Green aircraft will evolve naturally. Quiet operation is already sufficiently addressed by GFC I, which requires noise levels twice as stringent as the FAA demands.
Ground travel delays, combined with the high cost, high noise emissions, hi gh carbon emissions and poor MPG of LSAs, VLJs and flying cars make these CTOL aircraft very unlikely to reach production volumes necessary to achieve affordability. This makes it inappropriate to aim prize money toward either of those domains at this time

. The crucial importance of making GQ V/ E STOL aircraft safer and easier to use by adding robust computer

- aided safety, reliability, pilot

- assistance and precision landing capability should be the subject of a follow

- on GFC III.



### POLITICS
The great promise of GQ V/ E STOL aircraft as a transportation solution is that they can complement commercial air travel by restoring its door

- to

- door trip speeds, by eliminating the enormous ground travel delays. L arge manufacturing companies should be sponsoring and promo ting such transformative aircraft as a path toward a potentially enormous new market. That market was estimated by NASA’s Bushnell 2 to be potentially as large as $1 Trillion.
Cynicism expressed by uninformed, unimaginative or vested interests regarding the likelihood of such aircraft winning a large market is understandable in present day perspectives. However, the very purpose of a technology prize is to induce the most promising, urgent and transformative achievement that a risk

- averse, capital

- poor free market cannot otherwise produce. Best of all, a technology prize helps prevent industrial secrecy from wasting effort in isolation when networking with others in a more broadly shared knowledge and perspective yields better progress.



### CONCLUSION
NASA’s que st to make aviation Quiet and Green, the Green Flight Challenge (GFC), is an important beginning toward a future of mobility freedom. To maximize its benefits, a follow

- on GFC II should require fast GQ V/ E STOL aircraft. These are the only aircraft that wil l have both the capability and the consent to land in small spaces, very close to destination, eliminating the onerous delays of surface gridlock. This, along with enhanced computerized flight decks that make them easy to fly, is what will make them useful and popular.
The popularization of GQ V/ E STOL aircraft can revitalize aviation, transform our transportation system and bring many other societal benefits. Harnessing the frontier spirit of citizen innovators and universities to bring forth such aircraft would be the most practical and valuable of any NASA Challenge. Ironically, after aviation has conquered the sound barrier and soared high above the stratosphere, its most promising new frontier20

turns out to be that of mastering the ability to fly slowly, quietly, safely and close to the ground, like birds.

Footnotes and References:

1 AIAA paper 2003

- 264, entitled “ PERSONAL AIR VEHICLES: A RURAL/ REGIONAL AND INTRA

- URBAN ON

DEMAND TRANSPORTATION SYSTEM (available at: http://cafefoundation.org/v2/tech_lib.php then click on Title # 3 under the topic “NEXTGEN PAVs AND SATS”)

2 See: http://cafefoundation.org/v2/tech_lib.php Item # 11 und er NextGen: PAVs and SATS

3 http://stophelipad.org/helipads.shtml

4 DOD study on V/STOL: http://www.ac q.osd.mil/dsb/reports/2007

- 07

- Future_Need_for_VTOL_STOL_Aircraft.pdf page ix.

5 http://www.youtube.com/watch?v=4hZc

- LVhsw8 and
http://technorati.com/videos/youtube.com%2Fwatch%3Fv=w68WRWBeWzU and
http://technorati.com/videos/youtube.com%2Fwatch%3Fv=PTbkwgvxNDw and
http://technorati.com/videos/youtube.com%2Fwatch%3Fv=PTbkwgvxNDw

6 Sperling, Daniel, et al, Two Billion Cars , Oxford Press (2009).

7 http://www.publicpurpose.com/21st

- fl.htm

8 http://www.emich.edu/public/geo/557book/d373.calthorpe.html

9 In metropolitan areas, cars typically average < 35 mph trip speeds.

10 DOT 500 definitions: http://www.nhtsa.dot.gov/cars/rules/rulings/lsv/lsv.html

11 http://www.rita.dot.gov/publications/transportation_vision_2030/html/passenger_transportation.html

12 Calthorpe, Peter, The Regional City , Island Press (2001). http://books.google.com/books?id=qcwvvI0gfpoC&pg=PA53&lpg=PA53&dq=Peter+Calth orpe+walkability&source= bl&ots=dFBmoeGumf&sig=rNAZHqVJAYIMETxHV2KIquSdIvA&hl=en&ei=kL3MSohrhY60A8qzsaEB&sa=X&oi =book_result&ct=result&resnum=3

- v=onepage&q=&f=false

^Air Miles are typically 10% shorter than car miles due to curves in roads. This 10% air travel advantage is included in the graphs above.