World's Largest Square Parachute:
The X-38 parafoil
NASA X-38 team flies largest parafoil parachute in history
Posted: Feb. 6, 2000
A team developing a prototype International Space Station "lifeboat" called the X-38 Crew Return Vehicle successfully flew the largest parafoil parachute in history in January at the U.S. Army's Yuma Proving Ground, Arizona, as they released a parachute with an area almost one and a half times as big as the wings of a Boeing 747 jumbo jet.
The unmanned Jan. 19 parafoil test was part of the development of a re-entry system for the X-38 spacecraft. With an innovative combination of old and new technology and a streamlined development, the goal of the X-38 team is to develop a new human spacecraft for a fraction of the cost of any past program. Plans are to develop and build four operational X-38-based International Space Station Crew Return Vehicles for less than half of what it cost to manufacture a single Space Shuttle orbiter. The X-38 may become the first new U.S. human spacecraft to fly to and from space in more than 20 years. The parafoil recently tested in Arizona has a span of 143 feet and a total surface area of 7,500 square feet, making it the largest parafoil in the world.
"I think this is a world's record for a parafoil and it is a significant milestone and accomplishment for NASA," said John Muratore, who is leading the X-38 Crew Return Vehicle Project. "It puts us a major step closer toward our goal of providing the space station with the most flexible crew return option. This parafoil has the size and all the features to enable it to be used for returning humans from space."
For the test, an 18,000-pound pallet, simulating the actual X-38, was dropped from the back of a C-130 aircraft at an altitude of 21,500 feet. A 28-foot diameter extraction parachute pulled the test platform from the aircraft at an air speed of 130 miles per hour to begin the flight test. Once out of the aircraft, a newly designed 80-foot diameter drogue parachute stabilized and slowed the platform to a vertical airspeed of 62 miles per hour and enabled the parafoil to begin a five-stage deployment process. During its 11-minute long flight, the parafoil slowed the test pallet to a gentle vertical landing speed of less than eight miles per hour.

"This parafoil is so big there is no way that it can all deploy at once," said Brian Anderson, X-38 Project Manager. "Because of its size, the dynamic forces on the parachuteís structure are phenomenal." The size of the parafoil posed technical challenges for the X-38 team. One problem encountered in past tests has been to ensure that the parachute opens evenly. To solve this and make certain that the parachute opens symmetrically and rapidly, the team developed a revolutionary self-sealing floor vent system on the parafoil's underside. During the recent test, the parafoil opened to its full size in only 30 seconds. The parafoil was stitched together at Pioneer Aerospace's facility in Columbia, MS. Because of its
unprecedented size and strength, personnel at Pioneer nicknamed the parafoil "Sampson." A unique ripstop nylon material, customized stitching and other safety devices incorporated into the parafoil make the parachute not only the world's largest but also among the strongest. "The strength and quality of this parafoil is a real testimony to the skill and dedication of the men and women who built it," Muratore said.
The test was the 30th large-scale flight test conducted to support development of the parafoil, although this was the largest and most comprehensive test to date. In addition to tests at Yuma, four large-scale atmospheric flight tests of prototype X-38 vehicles have been completed at NASA's Dryden Flight Research Center using a smaller 5,500 square-foot parafoil. For those tests, increasingly complex X-38 vehicles have been launched from a B-52 carrier aircraft at increasingly higher altitudes. More such tests are planned during the next year and a half, leading up to a space flight test of the X-38 in 2002, when an unmanned vehicle now under construction at the Johnson Space Center will be released in orbit by the Space Shuttle to fly back to Earth.

The X-38's design is called a lifting body. Unlike the space shuttle, it does not have any wings. All of the lift necessary to maneuver and fly the X-38 comes from the lift generated by the flow of air over the body of the spacecraft and its fins. Lifting body configurations were studied extensively in the 1960s and 1970s as space entry vehicles. These vehicles all had very high landing speeds that proved difficult to control. The combination of the lifting body for the high speed part of entry followed by the parafoil for the final landing have proven to be a winner in the X-38 project. The large-scale drops of the parafoil were supplemented with well over 300 subscale drops.

"The subscale drops gave us the opportunity to test and refine techniques and gain the experience we needed for the large-scale drops at a much lower cost," said Jenny Stein, Project lead for the X-38 parachute systems. The 7,500 square-foot parafoil will be tested at Yuma again this spring and will then be integrated with one of the X-38 vehicles at Dryden for a test flight there late this year.

Project Description:

The X-38 Crew Return Vehicle (CRV) research project is designed to develop the technology for a prototype emergency crew return vehicle, or lifeboat, for the International Space Station. The project is also intended to develop a crew return vehicle design that could be modified for other uses, such as a joint U.S. and international human spacecraft that could be launched on the French Ariane-5 Booster.
The X-38 project is using available technology and off-the-shelf equipment to significantly decrease development costs. Original estimates to develop a capsule-type crew return vehicle were estimated at more than $2 billion. X-38 project officials have estimated that development costs for the X-38 concept will be approximately one quarter of the original estimate.

Off-the-shelf technology is not necessarily "old" technology. Many of the technologies being used in the X-38 project have never before been applied to a human-flight spacecraft. For example, the X-38 flight computer is commercial equipment currently used in aircraft and the flight software operating system is a commercial system already in use in many aerospace applications. The video equipment for the X-38 is existing equipment, some of which has already flown on the space shuttle for previous NASA experiments. The X-38's primary navigational equipment, the Inertial Navigation System/Global Positioning System, is a unit already in use on Navy fighters. The X-38 electromechanical actuators come from previous joint NASA, U.S. Air Force, and U.S. Navy research and development projects. Finally, an existing special coating developed by NASA will be used on the X-38 thermal tiles to make them more durable than those used on the space shuttles.

The X-38 itself was an unpiloted lifting body designed at 80 percent of the size of a projected emergency crew return vehicle for the International Space Station, although two later versions were planned at 100 percent of the CRV size. The X-38 and the actual CRV are patterned after a lifting-body shape first employed in the Air Force-NASA X-24 lifting-body project in the early to mid-1970s.

The current vehicle design is base lined with life support supplies for about nine hours of orbital free flight from the space station. ItÕs landing will be fully automated with backup systems which allow the crew to control orientation in orbit, select a deorbit site, and steer the parafoil, if necessary. The X-38 vehicles (designated V131, V132, and V-131R) are 28.5 feet long, 14.5 feet wide, and weigh approximately 16,000 pounds on average. The vehicles have a nitrogen-gas-operated attitude control system and a bank of batteries for internal power. The actual CRV to be flown in space was expected to be 30 feet long.

The X-38 project is a joint effort between the Johnson Space Center, Houston, Texas (JSC), Langley Research Center, Hampton, Virginia (LaRC) and Dryden Flight Research Center, Edwards, California (DFRC) with the program office located at JSC. A contract was awarded to Scaled Composites, Inc., Mojave, California, for construction of the X-38 test airframes. The first vehicle was delivered to the JSC in September 1996. The vehicle was fitted with avionics, computer systems and other hardware at Johnson. A second vehicle was delivered to JSC in December 1996.

Flight research with the X-38 at Dryden began with an unpiloted captive-carry flight in which the vehicle remained attached to its future launch vehicle, DrydenÕs B-52 008. There were four captive flights in 1997 and three in 1998, plus the first drop test on March 12, 1998, using the parachutes and parafoil. Further captive and drop tests occurred in 1999. In March 2000 Vehicle 132 completed its third and final free flight in the highest, fastest, and longest X-38 flight to date. It was released at an altitude of 39,000 feet and flew freely for 45 seconds, reaching a speed of over 500 miles per hour before deploying its parachutes for a landing on Rogers Dry Lakebed.

In the drop tests, the X-38 vehicles have been autonomous after airlaunch from the B-52. After they deploy the parafoil, they have remained autonomous, but there is also a manual mode with controls from the ground.