HISTORIAN'S CORNER - July, 2005

BY: Matt Grogan

The Glenn L. Martin Co. Baltimore history is full of important aircraft projects while Lockheed Martin Denver is known more for Launch Vehicle and Spacecraft accomplishments. 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 Field in CA had been interested in lifting body earth reentry vehicles vs; ballistic reentry vehicles, in order to provide some control over the trajectory of a spacecraft returning from space. The symmetrically shaped conical space capsules used for reentry vehicles in the Mercury, Gemini programs and Apollo program provided the astronauts with no maneuvering control capability after reentry, and required a water landing. In 1962, NASA'S Flight Research Center (FRQ at Edwards, CA, built the first manned lifting body aircraft based on research done at NASA Ames, the M217-1 (Ref. 1). From this beginning, five more experimental manned aircraft were built over the next 11 years to find an aerodynamic shape that would allow a manned vehicle to reenter the atmosphere from Earth orbit, control its trajectory through the atmosphere, and glide to a landing on a conventional runway. The Air Force also was interested in lifting body research due to its interest in a future space plane. (The Air Force space plane eventually gave way to the NASA Space Shuttle in the 70's). Six manned lifting body aircraft were designed and built by NASA and the Air Force, Northrop Corporation and Martin Marietta Co. These aircraft were flown as joint Air Force/NASA programs between 1963 and 1975 at Edwards to 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 six planes in this series.

The first X-24, the X-24A, was built by Martin Marietta Baltimore as an Air Force project. Its first flight was in 1967. In 1964 Martin Baltimore had successfully completed an unmanned precursor program with the Air Force called PRIME that tested the reentry characteristics of a wingless lifting body called the SV-5 (REF 3). The X-24A was roughly 24 ft. long and 13 ft. wide and designed with the same SV-5 lifting body shape as PRIME (Ref. 4). It was constructed of conventional aluminum, had a flat bottom, rounded bulbous top, 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 successfully validated 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 Dynamics Laboratory configuration for a more maneuverable vehicle with a hypersonic UD ratio of 2.5. The higher lift design was needed by space planes like the Space Shuttle to provide greater maneuvering capability to glide to an accurate landing on a conventional runway after reentry from Earth orbit. The Air Force contracted with Martin Marietta Denver in the early 70's to modify the existing X-24A. The resulting X-24B had a delta shaped wing with a double tail and was 13 ft. longer and almost 6 ft. wider than the X-24A, but used the same cockpit, engine, basic structural framework and subsystems to minimize cost. The increased wing area and L/D increased the cross range capability of 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 needed to simulate the space shuttle gliding return to its base after reentry from space. The X-24B test flight program consisted of 36 flights starting in 1973 and on August 5, 1975, the X-24B piloted by John Manke, made the first landing of a lifting body aircraft on a conventional concrete runway at Edwards. Nine more flights were made, including a second landing on a conventional runway before the X-24B program ended in November 1975 (Ref 5). Since that time the Space Shuttle has reentered from space and maneuvered through the atmosphere to successful landings numerous times. The X-24B vehicle is on display at the Air Force Museum, Wright-Patterson Air Force Base, OH, and an X-24A model is on display at the Air Force Academy Museum in Colorado Springs (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-24 programs, as well as any other recollections.

Through several sources, we think the X-24B Denver program included Dick Boss, Dick Brackeen, Frank Matvestuto (sp?), perhaps Joe Putegnat, with Carol Guyot as the secretary for the program. Please contact me (Matt Grogan) if you 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