HISTORIAN'S CORNER - July, 2005

BY: Matt Grogan

The Glenn L. Martin Co. Baltimore history is full of important aircraft projectswhile Lockheed Martin Denver is known more for Launch Vehicle and Spacecraftaccomplishments. But in 1972, Martin Marietta Denver actually built an airplane,the X-24B! How that happened is interesting stuff .

As early as 1957, researchers at NASA Ames Research Center at Moffett Fieldin CA had been interested in lifting body earth reentry vehicles vs; ballisticreentry vehicles, in order to provide some control over the trajectory ofa spacecraft returning from space. The symmetrically shaped conical spacecapsules used for reentry vehicles in the Mercury, Gemini programs and Apolloprogram provided the astronauts with no maneuvering control capability afterreentry, and required a water landing. In 1962, NASA'S Flight Research Center(FRQ at Edwards, CA, built the first manned lifting body aircraft based onresearch done at NASA Ames, the M217-1 (Ref. 1). From this beginning, fivemore experimental manned aircraft were built over the next 11 years to findan aerodynamic shape that would allow a manned vehicle to reenter the atmospherefrom Earth orbit, control its trajectory through the atmosphere, and glideto a landing on a conventional runway. The Air Force also was interestedin lifting body research due to its interest in a future space plane. (TheAir Force space plane eventually gave way to the NASA Space Shuttle in the70's). Six manned lifting body aircraft were designed and built by NASA andthe Air Force, Northrop Corporation and Martin Marietta Co. These aircraftwere flown as joint Air Force/NASA programs between 1963 and 1975 at Edwardsto test different lifting body configurations. In rough chronological order,these programs included the M2F-1 (NASA), M2F-2 (NASA/Northrop), M2F-3 (NASA),the X-24A (Air Force/Martin Baltimore), HL-10 (NASA/Northrop), and the X-24B(Air Force/Martin Denver). Reference 2 provides a nice summary of the sixplanes in this series.

The first X-24, the X-24A, was built by Martin Marietta Baltimore as an AirForce project. Its first flight was in 1967. In 1964 Martin Baltimore hadsuccessfully completed an unmanned precursor program with the Air Force calledPRIME that tested the reentry characteristics of a wingless lifting bodycalled the SV-5 (REF 3). The X-24A was roughly 24 ft. long and 13 ft. wideand designed with the same SV-5 lifting body shape as PRIME (Ref. 4). Itwas constructed of conventional aluminum, had a flat bottom, rounded bulboustop, triple tail, and a hypersonic Lift-to-Draft ratio (LID) of 1.4 (Ref.3,5). The X-24A flew 28 times at Edwards from 1967 to 1970, and successfullyvalidated the concept that a lifting body vehicle could be landed unpowered.All landings were on Rogers Dry Lake at Edwards.

The X-24B research program was initiated to test an Air Force Flight DynamicsLaboratory configuration for a more maneuverable vehicle with a hypersonicUD ratio of 2.5. The higher lift design was needed by space planes like theSpace Shuttle to provide greater maneuvering capability to glide to an accuratelanding on a conventional runway after reentry from Earth orbit. The AirForce contracted with Martin Marietta Denver in the early 70's to modifythe existing X-24A. The resulting X-24B had a delta shaped wing with a doubletail and was 13 ft. longer and almost 6 ft. wider than the X-24A, but usedthe same cockpit, engine, basic structural framework and subsystems to minimizecost. The increased wing area and L/D increased the cross range capabilityof the X-24B from about 1000 nm to about 3000 nm (Ref. 3).

Each of the X-24 vehicles were carried to 45,000 ft, by a B-52, released,and then powered by an XLR-1 1 rocket engine to the altitude and speeds neededto simulate the space shuttle gliding return to its base after reentry fromspace. The X-24B test flight program consisted of 36 flights starting in1973 and on August 5, 1975, the X-24B piloted by John Manke, made the firstlanding of a lifting body aircraft on a conventional concrete runway at Edwards.Nine more flights were made, including a second landing on a conventionalrunway before the X-24B program ended in November 1975 (Ref 5). Since thattime the Space Shuttle has reentered from space and maneuvered through theatmosphere to successful landings numerous times. The X-24B vehicle is ondisplay at the Air Force Museum, Wright-Patterson Air Force Base, OH, andan X-24A model is on display at the Air Force Academy Museum in ColoradoSprings (Ref. 7).

Our Historian archives contain several pictures of the X-24B under construction.I am interested in obtaining names of the people that worked on the X-24programs, as well as any other recollections.

Through several sources, we think the X-24B Denver program included DickBoss, Dick Brackeen, Frank Matvestuto (sp?), perhaps Joe Putegnat, with CarolGuyot as the secretary for the program. Please contact me (Matt Grogan) ifyou can add to the list.

References:

1. Dryden Research Center web site,
www.nasa.gov/centers/dryden/history/pastprojects/LiftingAndex.htmI
2. Aztecdoug's Aerospace Website, Lifting Bodies, home.earthlink.netl-aztecdougfindex.htmI
3. Email from Jim Sterhardt, 06/06/05
4. Harwood, William, "Raise Heaven and Earth", pgs 387-389, 1993
5. Dryden Research Center web site, www.dfrc.nasa.gov/Gallery/Movie/X-24B
6. Astronautica, Encyclopedia, www.astronautix.com/crafttx24b.htm
7. Aviation Enthusiast Comer, aeroweb.brooklyn.cuny.edu/museums/museums.htm