NASA X-38
From Wikipedia, the free encyclopedia
| X-38 | |
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| Type | Crew Return Vehicle |
| Manufacturer | Scaled Composites (prototypes) |
| Maiden flight | 1999 |
| Status | Cancelled 29 April 2002 |
| Primary user | NASA |
| Number built | 2 atmospheric vehicles 1 orbital vehicle (incomplete) |
| Developed from | Martin-Marietta X-24 |
The X-38 Crew Return Vehicle (CRV) was a prototype for a wingless lifting body reentry vehicle that was to be used as a Crew Return Vehicle for the International Space Station (ISS). The X-38 was developed to the point of a drop test vehicle before its development was cancelled in 2002 due to budget cuts. [1]
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[edit] History
The crew size for the ISS depends upon the crew return capability: the crew is limited to three because the Russian Soyuz TMA vehicle that will remain docked to the ISS can only hold three people. Since it is imperative that the crew members be able to return to Earth if there is a medical emergency or if other complications arise, a Crew Return Vehicle able to hold up to seven crew members was planned from the outset: this would have allowed the full complement of seven astronauts to live and work onboard the ISS. NASA has designed several crew return vehicles over the years with varying levels of detail.[2]
[edit] Development
X-38 was the program under leadership of NASA Johnson Space Center to build a series of incremental flight demonstrators for the proposed Crew Return Vehicle. In an unusual move for an X-plane, the program involved the European Space Agency and the German Space Agency DLR. It was originally called X-35. The program manager was John Muratore, while the Flight Test Engineer was future NASA astronaut Michael E. Fossum.
The X-38 design used a wingless lifting body concept originally developed by the U.S. Air Force in the mid-1960s during the X-24 program, and it was Muratore's brainchild.
The X-38 program used unmanned mockups to test the CRV design. The flight models were:
- X-38 V-131
- X-38 V-132
- X-38 V-131R, which was the V-131 prototype reworked with a modified shell
- X-38 V-201, which was an orbital prototype to be launched by the Space Shuttle
- X-38 V-133 and V-202 were also foreseen at some point in the project but were never built.
The X-38 V-131 and V-132 shared the aerodynamic shape of the X-24A. This shape had to be enlarged for the Crew Return Vehicle needs (crew of seven astronauts) and redesigned, especially in the rear part, which became thicker.
The X-38 V-131R was designed at 80 percent of the size of a CRV (24.5 ft long, 11.6 ft wide, 8.4 ft high), and featured the final redesigned shape (Two later versions, V-133 and V-201, were planned at 100 percent of the CRV size). The 80% scale versions were flown at 15,000 to 24,000 pound weight. The X-38 V-201 orbital prototype was 80 percent complete, but never flown.
In tests the V-131, V-132 and V-131R were dropped by a B-52 from altitudes of up to 45,000 ft (13,700 m), gliding at near transonic speeds before deploying a drogue parachute to slow them to 60 mph (95 km/h). The later prototypes had their descent continue under a 7,500 ft² (700 m²) parafoil wing, the largest ever made. Flight control was mostly autonomous, backed up by a ground-based pilot.
The X-38 project cancellation was announced on April 29, 2002 [1] due to budget concerns.
[edit] Design
Following the jettison of a deorbit engine, the X-38 would have glided from orbit and used a steerable parafoil for its final descent and landing. The high speeds at which lifting body aircraft operate make them dangerous to land. The parafoil would have been used to slow the vehicle and make landing safer. The landing gear consisted of skids rather than wheels: the skids worked like sleds so the vehicle would have slid to a stop on the ground.
Both the shape and size of the X-38 were different from that of the Space Shuttle. The Crew Return Vehicle would have fit into the payload bay of the shuttle. This does not, however, mean that it would have been small. The X-38 weighed 10,660 kg and was 9.1 meters long. The battery system, lasting nine hours, was to be used for power and life support. If the Crew Return Vehicle was needed, it would only take two to three hours for it to reach Earth.
The parafoil parachute, employed for landing, was derived from technology developed by the U.S. Army. This massive parafoil deploys in stages for optimum performance. A drag chute would have been released from the rear of the X-38. This drag chute would have been used to stabilize and slow the vehicle down. The giant parafoil — area of 687 square meters — was then released. It would open in four stages (a process called staging). While the staging process only takes 45 seconds, it is important for a successful chute deployment. Staging prevents high-speed winds from tearing the parafoil.
The spacecraft’s landing was to be completely automated. Mission Control would have sent coordinates to the onboard computer system. This system would also have used wind sensors and the Global Positioning System (a satellite-based coordinate system) to coordinate a safe trip home. Since the Crew Return Vehicle was designed with medical emergencies in mind, it made sense that the vehicle could find its way home automatically in the event that crew members were incapacitated or injured. If there was a need, the crew would have the capability to operate the vehicle by switching to the backup systems. In addition, seven high altitude low opening (HALO) parachute packs were included in the crew cabin, a measure designed to provide for the need to jettison the craft.
An Advanced Docking Berthing System (ADBS) was designed for the X-38 and the work on it led to the Low Impact Docking System the Johnson Space Center later created for the planned vehicles in Project Constellation.
[edit] Specifications
This aircraft article is missing some (or all) of its specifications. If you have a source, you can help Wikipedia by adding them.[edit] See also
Related development
- Martin-Marietta X-24
- HiMAT Remotely Piloted Vehicle [1]
Comparable aircraft
[edit] Notes
[edit] References
- NASA Dryden Fact Sheets. NASA. Retrieved on 2006-09-13.
- NASA - Current Research Projects - X-38 CRV. NASA. Retrieved on 2006-09-13.
- X38/CRV FDIR. NASA's Smart Systems Research Lab. Retrieved on 2006-09-13.
- Crew Return Vehicle (CRV). ESA. Retrieved on 2006-09-14.
[edit] External links
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