Martin Marietta X-24B
|The X-24B in flight|
|First flight||1 August 1973|
|Retired||26 November 1975|
|Status||Out of service|
|Primary users||United States Air Force
|Number built||1 (rebuilt X-24A)|
|Developed from||Martin Marietta X-24A|
The Martin Marietta X-24B was an experimental US aircraft developed from a joint USAF-NASA program named PILOT (1963–1975). It was designed and built to test lifting body concepts, experimenting with the concept of unpowered reentry and landing, later used by the Space Shuttle. The X-24 was drop launched from a modified B-52 Stratofortress at high altitudes before igniting its rocket engine; after expending its rocket fuel, the pilot would glide the X-24 to an unpowered landing.
Design and development
The X-24 was one of a group of lifting bodies flown by the NASA Flight Research Center (now Armstrong Flight Research Center) in a joint program with the U.S. Air Force at Edwards Air Force Base in California from 1963 to 1975. The lifting bodies were used to demonstrate the ability of pilots to maneuver and safely land wingless vehicles designed to fly back to Earth from space and be landed like an airplane at a predetermined site.
The X-24B's design evolved from a family of potential reentry shapes, each with higher lift-to-drag ratios, proposed by the Air Force Flight Dynamics Laboratory. To reduce the costs of constructing a research vehicle, the Air Force returned the X-24A to the Martin Marietta Corporation (as Martin Aircraft Company became after a merger) for modifications that converted its bulbous shape into one resembling a "flying flatiron"—rounded top, flat bottom, and a double delta planform that ended in a pointed nose.
There were a variety of "X-24C" proposals floated between 1972 and 1978. Perhaps the most notable was a Lockheed Skunk Works design, the L-301, which was to use scramjets to reach a top speed of Mach 8.
The X-24B made two precise landings on the main concrete runway at Edwards which showed that accurate unpowered reentry vehicle landings were operationally feasible. Pilots on these missions would fly steep descents and then perform a "flare out" maneuver at high speeds to make a 200 mph landing, simulating the landing speed and approach pattern of the Space Shuttle orbiter. These missions, flown by Manke and Air Force Maj. Mike Love, represented the final milestone in a program that helped write the flight plan for the NASA Space Shuttle program.
Top speed achieved by the X-24B was 1,164 mph (1873 km/h), and the highest altitude it reached was 74,130 feet (22.59 km). The pilot on the last powered flight of the X-24B was Thomas C. McMurtry, who also flew the last X-15 flight about seven years earlier.
The X-24B was the last aircraft to fly in Dryden's Lifting Body program. The X-24B was flown 36 times.
- X-24B pilots
- John A. Manke - 16 flights
- Michael V. Love - 12 flights
- William H. Dana - 2 flights
- Einar K. Enevoldson - 2 flights
- Thomas C. McMurtry - 2 flights
- Francis Scobee - 2 flights
- Crew: one pilot
- Length: 37 ft 6 in (11.43 m)
- Wingspan: 19 ft 0 in (5.79 m)
- Height: 9 ft 7 in (2.92 m)
- Wing area: 330 ft² (30.7 m²)
- Empty weight: 8,500 lb (3,855 kg)
- Loaded weight: 11,800 lb (5,350 kg)
- Max. takeoff weight: 13,800 lb (6,260 kg)
- Powerplant: 1 × XLR-11-RM-13 four-chamber rocket engine, 8,480 lbf (37.7 kN)
- Maximum speed: 1,164 mph (1,873 km/h)
- Range: 45 miles (72 km)
- Service ceiling: 74,130 ft (22.59 km)
- Wing loading: 205 kg/m² ()
- Thrust/weight: 0.71
- Related development
- Aircraft of comparable role, configuration and era
- Related lists
- Reed, R. Dale; Darlene Lister (2002). Wingless Flight: The Lifting Body Story. University Press of Kentucky. ISBN 0-8131-9026-6. also available as a PDF file.
- "MARTIN X-24B". National Museum of the US Air Force. 26 August 2009. Retrieved 25 March 2013.
- "X-24B launch - air drop from mothership". Dryden Flight Research Center. Retrieved 25 March 2013.
- Jenkins, Dennis R. (2001). Space Shuttle: The History of the National Space Transportation System (3rd ed.). Voyageur Press. ISBN 0-9633974-5-1.
- "X-24B Precision Landings Proved That Shuttle Could Land Unpowered". NASA.gov. 1 July 2011. Retrieved 25 March 2013.
Miller, Jay. The X-Planes: X-1 to X-45. Hinckley, UK: Midland, 2001.
Rose, Bill, 2008. Secret Projects: Military Space Technology. Hinckley, England: Midland Publishing.
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