NASA 

National Aeronautics and 

Facts

Space Administration 

Dryden Flight Research Center 

P.O. Box 273

Edwards, California 93523 

Voice 661-276-3449 

FAX 661-276-3566 

pao@dfrc.nasa.gov FS-2002-09-045 DFRC 

Spacewedge 

Spacewedge vehicle decsending with 288 sq. foot parafoil. NASA photo EC 92-04271-4 

From October 1991 to December 1996, NASA's Dryden Flight Research Center, Edwards, Calif., conducted a research 

program known as the Spacecraft Autoland Project to determine the feasibility of the autonomous recovery of a spacecraft 

using a ram-air parafoil system for the final stages of flight, including a precision landing. The NASA Johnson Space 

Center (JSC), Houston, Texas, and the U.S. Army also participated in various phases of the program, with the Charles 

Stark Draper Laboratory developing the software for Wedge 3 under contract to the Army. Four generic spacecraft models 

(each called a Spacewedge or simply a Wedge) were built to test the feasibility of the concept and also of the use of a 

parafoil for delivering Army cargo. Technology developed during the program has applications for future spacecraft 

recovery systems. Spacewedge demonstrated precision flare and landing into the wind at a predetermined location. The 

program showed that a flexible, deployable system using autonomous navigation and landing was a viable and practical 

way to recover spacecraft. 

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Program Development 

NASA researchers conducted a flight test program in 

California to develop and refine the Spacewedge vehicle 

design. The first test vehicle (Wedge 1) was just four feet 

long and weighed 120 pounds. It was initially launched 

from a hillside near Tehachapi to evaluate general flying 

qualities, including gentle turns and landing flare. Two of 

these slope soar flights were made on April 23, 1992, with 

approximately 15-knot winds, achieving altitudes of 10 to 

50 feet above the ground. The test program then moved to 

Rogers Dry Lake at Edwards Air Force Base, and to a sport 

parachute (Skydive) drop zone at California City. 

A second vehicle (known as Inert Spacewedge or Wedge 2) 

was fabricated with the same external geometry and weight 

as Wedge 1. It was initially used to validate parachute 

deployment, harness design, and drop separation characteristics. Wedge 2 was inexpensive, without internal components, and considered expendable. It was first dropped 

from a Cessna U-206 Stationair on June 10, 1992, during 

flight three. A second drop of Wedge 2 verified repeatability of the parachute deployment system. The Wedge 2 

vehicle was also used for the first drop from a Rans S-12 

ultralight modified as a remotely piloted vehicle (RPV) 

during flight nine on August 14, 1992. Wedge 2 was later 

instrumented and used for ground tests, mounted on top of 

a van, and became the primary test vehicle for the Phase II 

test series. 

Thirty-six flight tests were made during Phase I, the last 

taking place on February 12, 1993. These flights verified 

the manual control and autonomous landing systems of the 

vehicle. Eleven of the tests were remotely controlled. 

Most were launched from the Cessna U-206 Stationair. 

Only flights nine and 12 were launched from the Rans S-12 

RPV. 

Phase II of the program ran from March 1993 to March 

1995, and encompassed 45 flights. It continued the research for NASA JSC, using a smaller parafoil for higher 

wing (parachute) loading. For Phase II, NASA Dryden 

engineers developed a new guidance, control, and instrumentation system. 

Phase III, encompassing 34 flights, evaluated the Precision 

Guided Airdrop Software (PGAS) system using Wedge 3 

from June 14, 1995, to November 20, 1996. Researchers 

used Wedge 3 to develop a guidance system to be used by 

the Army for precision offset cargo delivery. The Wedge 3 

vehicle was four feet long and was dropped at weights 

varying from 127 to 184 pounds. Unlike Wedges 1 and 2, 

its flight objectives were not tied to the terminal recovery 

of a space vehicle, and it was not called a Spacewedge. 

(There was also a fourth wedge, but it never flew and 

Wedge 2 under Rans S-12 RPV (EC 92-08148-4), and Wedge 3 

being placed in Cessna U-206 (EC 96-43660-3). 

served only as backup hardware to Wedge 3.) 

Spacewedge Design 

Two Spacewedge shapes, resembling half-cones with a 

flattened bottom, were used for four airframes that represented generic hypersonic vehicle configurations. Wedge 

1 and Wedge 2 had sloping sides, and the underside of the 

nose sloped up slightly. Wedge 3 and Wedge 4 had 

flattened sides, to create a larger internal volume for 

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instrumentation. The Spacewedge vehicles were 48 inches 

long, 30 inches wide, and 21 inches high. The basic weight 

was 120 pounds, although various configurations ranged 

from 127 to 184 pounds during the course of the test 

program. Wedge 1 had a tubular steel structure, covered 

with plywood on the rear and underside to withstand hard 

landings. It had a fiberglass-covered wooden nose, and 

removable aluminum upper and side skins. Wedge 2, 

originally uninstrumented, was later configured with 

instrumentation. It had a fiberglass outer shell, with 

plywood internal bulkheads and bottom structure. Wedge 3 

was constucted as a two-piece fiberglass shell, with a 

plywood and aluminum shelf for instrumentation. 

In the manual control mode, the vehicle was flown using 

radio uplink. In the autonomous mode, it was controlled 

using a small computer which received inputs from 

onboard sensors. Selected sensor data were recorded onto 

several onboard data loggers. 

A commercially-available 288 sq. foot ram-air parafoil was 

selected for Phase I tests. Such parachutes are commonly 

used by sport parachutists. The docile flight characteristics, 

low loading factor, and proven design allowed the project 

team to concentrate on developing the vehicle rather than 

the parachute. With the exception of lengthened control 

lines, the parachute was not modified. Its large size 

allowed the vehicle to land without flaring, and without 

sustaining damage. For Phase II and III, a smaller (77 sq. 

foot) parafoil was used to allow for a wing (actually, 

parafoil) loading more representative of space vehicle or 

Army cargo applications. 

The Spacewedge Phase I and II instrumentation system 

architecture was driven by cost, hardware availability, and 

program evolution. (During Phase I, Wedge 2 had an inert 

payload but was outfitted with instrumentation for Phase II.) 

The essential items consisted of the uplink receiver, Global 

Positioning System receiver and antenna, barometric altimeter, flight control computer, servoactuators, electronic 

compass, and ultrasonic altimeter. Added instrumentation 

included a video camera and camcorder, control position 

transducers, a data logger, and a pocket personal computer. 

Schematic showing Spacewedge Phase II instrumentation for 

Wedge 2. 

NASA employees integrated these off-the-shelf components. 

Wedge 3 instrumentation was considerably more complex to 

accommodate the PGAS software system. 

Spacewedge control systems had programming, manual, and 

autonomous flight modes. The programming mode was used 

to start up and configure the flight control computer. Researchers entered the landing coordinates, decision altitudes, 

and ground wind velocity at the landing site. 

The manual mode used a radio control model receiver and 

uplink transmitter, configured to allow the ground pilot to 

enter either brake (pitch) or turn (yaw) commands. The 

vehicle reverted to manual mode whenever the transmitter 

controls were moved, even when the autonomous mode was 

selected. 

The autonomous mode allowed the vehicle to navigate to the 

landing point, maintain the holding pattern while descending, 

enter the landing pattern, and initiate the flare maneuver. 

There were three decision altitudes: at the start of the landing 

pattern, at the turn to final approach, and upon flare initiation. 

Spacewedge Flight Profile 

When at high altitude and offset from the landing point, the 

vehicle was commanded to fly to the landing point. If the 

landing point was reached while at or above the first decision 

altitude (typically set to 300 feet), then the vehicle was 

commanded to fly a holding pattern until it descended below 

the decision altitude. The holding pattern was an upwind 

racetrack aligned with the wind (as input in the programming 

mode). Each lap of the racetrack pattern consumed approximately 500 feet of altitude. Below the first decision altitude, 

the vehicle was commanded to enter the landing pattern. 

The point to turn to final approach was based on a second 

Three-view drawings of Spacewedge shape, Wedge 1 (left), and decision altitude, typically 150 to 200 feet. This second 

PGAS Wedge 3 (right). altitude was a function of the wind and the position relative to 

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the landing point. Once on final approach, the vehicle was 

commanded to maximum speed, steering commands were 

locked out, and the ultrasonic altitude sensor was activated. 

At a final decision altitude of about 26 feet, the flare was 

initiated by commanding full brake. Touchdown occurred 

approximately four seconds later. 

Wedge 3 in flight. NASA photo EC 95-43135-1 

Key Personnel 

Many Dryden employees and partners worked on this 

project. These included R. Dale Reed, who originated the 

concept of conducting a subscale flight test at Dryden. He 

also participated in the flight testing. Alexander Sim 

managed the project and participated in the flight tests and 

documentation. James Murray served as the principal 

Dryden investigator and as lead person for all systems 

integration for Phases I and II. He designed and fabricated 

much of the instrumentation for Phase II and was the lead 

person for flight data retrieval and analysis in Phases II 

and III. David Neufeld performed the wedge systems 

mechanical integration for all three phases and served as 

parachute rigger, among other duties. 

From Draper Lab, Philip Hattis served as the project 

technical director for his organization’s significant contributions to Phase III. For the Army, Richard Benney was 

the technical point of contact, while Rob Meyerson served 

as the technical point of contact for NASA JSC and 

provided the specifications for the Spacewedges. 

Spacewedge Contributions 

NASA is studying a variety of vehicles for use in returning 

humans and cargo from space to Earth. Although the 

configuration of these vehicles has not yet been finalized, 

several capsules and lifting body designs are under consideration. 

Potential NASA users for a deployable, precision, autonomous landing system include proposed vehicles with 

human crews as well as planetary probes and booster 

recovery systems. Military applications include the use of 

autonomous gliding parachute systems on aircraft ejection 

seats, and high-altitude, offset delivery of cargo to minimize danger to aircraft and crews. Such a cargo delivery 

system could also be used for providing humanitarian aid. 

The Spacecraft Autoland Project, or Spacewedge, was an 

example of the innovative engineering work that is typical at 

NASA Dryden. Off-the-shelf equipment was used whenever possible in the project to keep costs low and to reduce 

development time. A relatively inexpensive Rans S-12 

ultralight aircraft was modified as a RPV drop aircraft until 

the less labor-intensive unmodified Cessna U-206 had 

proved its viability. The four Spacewedge research vehicles are currently in storage at NASA Dryden Flight 

Research Center, Edwards, Calif. 

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Spacewedge landing at California City drop zone. NASA photo 

EC92-06186-2 

References: 

Philip D. Hattis, Robert J. Polutchko, Brent D. Appleby, 

Timothy M. Barrows, Thomas J. Fill, Peter M. Kachmar, 

Terrence D. McAteer, “Final Report: Development and 

Demonstration Test of a Ram-Air Parafoil Precision 

Guided Airdrop System,” Volumes 1 through 4 (Report 

CSDL-R-2752, Oct. 1996) and Addendum (Report CSDLR-2771, Dec. 1996). 

James E. Murray, Alex G. Sim, David C. Neufeld, Patrick 

K. Rennich, Stephen R. Norris, Wesley S. Hughes, “Further

Development and Flight Test of an Autonomous Precision 

Landing System Using a Parafoil” (NASA TM-4599, July 

1994). 

Alex G. Sim, James E. Murray, David C. Neufeld, R. Dale 

Reed, “Development and Flight Test of a Deployable 

Precision Landing System,” AIAA Journal of Aircraft, Vol. 

31, Number 5, pages 1101 - 1108, Sept. 1994. 

Alex G. Sim, James E. Murray, David C. Neufeld, R. Dale 

Reed, “The Development and Flight Test of a Deployable 

Precision Landing System for Spacecraft Recovery” 

(NASA TM-4525, Sept. 1993). 

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