X-23 with X-24 - X-23 with Orbital X-24 Credit: Lockheed Martin. 28,806 bytes. 342 x 303 pixels.

The X-24A was the Martin Corporation's subsonic test version of the US Air Force's preferred manned lifting body configuration. This was flat-bellied with canted vertical stabilizers at the end of the rounded upper body. It was of the same configuration as the subscale X-23 Prime vehicle tested on suborbital flights in 1966 - 1967. Martin and the USAF hoped it would lead to a larger Titan III-launched manned orbital ferry vehicle (cinematically embodies in the 'XRV' spacecraft in the 1969 film version of Martin Caidin's novel 'Marooned'). The X-24A was air-launched from an NB-52 carrier aircraft and reached a maximum speed of Mach 1.6 and a maximum altitude of 21,800 m during its flight test. The X-24A handled well as a glider, but in powered flight it exhibited a nose-up trim change that prevented it from flying at low angles of attack. Air Force interest then focused on 'high fineness lifting body' configurations and the X-24A airframe was converted to the X-24B configuration. The X-24A was also known as the SV-5P configuration. Two nearly identical SV-5J's, equipped with a Pratt and Whitney J60-PW-1 jet engine of 1360 kgf, were built but never flown.

Total Length: 7.5 m. Maximum Diameter: 4.2 m. Total Mass: 5,192 kg. Total Propellants: 2,480 kg. Primary Engine Thrust: 3,845 kgf. Main Engine Propellants: LOX/Alcohol. Main Engine Isp: 225 sec. Total spacecraft delta v: 1,300 m/s. Electrical System: Batteries.

• Module: Air Vehicle. Purpose: Manned space plane. Propellants: 2480 L/D Hypersonic: 1.4. Maneuver System Thrust: 3,845 kgf. Backup Maneuver System Thrust: 454 kgf. Maneuver System Propellants: LOX/Alcohol. Maneuver System Isp: 225 sec. Maneuver system delta v: 1,300 m/s. Electric system type: Batteries. Battery: 194.0 Ah.

Alfred J. Eggers, Jr., of the NACA Ames Aeronautical Laboratory, worked out a semiballistic design for a manned reentry spacecraft.

The lifting body concept was first tested at Dryden with a plywood prototype designated the M2-F1 built in late 1962. It featured a plywood shell built by Gus Briegleb, a sailplane builder from Mirage Dry Lake, Calif., placed over a tubular frame built at Dryden. The M2-F1 was towed aloft, first behind an auto and then a C-47 more than 100 times, to validate basic lifting body stability and control characteristics. This led to establishment of the formal program which resulted in the HL-10, M2-F2, M2-F3, X-24A, and X-24B lifting bodies.

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X-24A Credit: © Mark Wade. 5,037 bytes. 397 x 449 pixels.

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Glide. Maximum Speed - 763 kph. Maximum Altitude - 13720 m. Flight Time - 217 sec.

Glide. Maximum Speed - 735 kph. Maximum Altitude - 13720 m. Flight Time - 253 sec.

Glide. Maximum Speed - 615 kph. Maximum Altitude - 12190 m. Flight Time - 270 sec.

Glide. Maximum Speed - 647 kph. Maximum Altitude - 12190 m. Flight Time - 232 sec.

Glide. Maximum Speed - 637 kph. Maximum Altitude - 12190 m. Flight Time - 257 sec.

Glide. Maximum Speed - 623 kph. Maximum Altitude - 12190 m. Flight Time - 238 sec.

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Lifting Bodies - Lifting Bodies Comparative Credit: © Mark Wade. 3,968 bytes. 620 x 171 pixels.

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Glide. Maximum Speed - 730 kph. Maximum Altitude - 13720 m. Flight Time - 266 sec.

Glide. Maximum Speed - 819 kph. Maximum Altitude - 14326 m. Flight Time - 258 sec.

First powered flight. Maximum Speed - 919 kph. Maximum Altitude - 13533 m. Flight Time - 424 sec.

Maximum Speed - 919 kph. Maximum Altitude - 17892 m. Flight Time - 435 sec.

Maximum Speed - 981 kph. Maximum Altitude - 17587 m. Flight Time - 408 sec.

2 chambers. Maximum Speed - 795 kph. Maximum Altitude - 13594 m. Flight Time - 513 sec.

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X-24A Credit: NASA. 14,104 bytes. 391 x 217 pixels.

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Maximum Speed - 1051 kph. Maximum Altitude - 18593 m. Flight Time - 432 sec.

Maximum Speed - 996 kph. Maximum Altitude - 17678 m. Flight Time - 388 sec.

Maximum Speed - 1047 kph. Maximum Altitude - 19477 m. Flight Time - 413 sec.

2 chambers. Maximum Speed - 737 kph. Maximum Altitude - 12649 m. Flight Time - 479 sec.

First supersonic flight. Maximum Speed - 1261 kph. Maximum Altitude - 20696 m. Flight Time - 411 sec.

Maximum Speed - 1446 kph. Maximum Altitude - 21763 m. Flight Time - 417 sec.

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Lifting Bodies - Manned Lifting Bodies Credit: NASA. 11,596 bytes. 467 x 127 pixels.

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Maximum Speed - 1093 kph. Maximum Altitude - 15819 m. Flight Time - 462 sec.

Powell's check flight, glide. Maximum Speed - 700 kph. Maximum Altitude - 13716 m. Flight Time - 235 sec.

Maximum Speed - 1606 kph. Maximum Altitude - 20544 m. Flight Time - 447 sec.

Maximum Speed - 1064 kph. Maximum Altitude - 17343 m. Flight Time - 437 sec.

Fastest X-24 flight. Maximum Speed - 1667 kph. Maximum Altitude - 21488 m. Flight Time - 446 sec.

Maximum Speed - 1477 kph. Maximum Altitude - 21610 m. Flight Time - 423 sec.

3 chambers. Maximum Speed - 1265 kph. Maximum Altitude - 19903 m. Flight Time - 548 sec.

Final X-24A flight. Maximum Speed - 867 kph. Maximum Altitude - 16581 m. Flight Time - 517 sec.

NASA, North Carolina State University and North Carolina A&T University built a full-scale model of the HL-20 for human factors research on the concept. In the end, space station Freedom became the International Space Station. As the initial crew emergency rescue vehicle, the Russian Soyuz spacecraft was selected. However NASA, looking for a higher-capacity alternative and concerned about reliable availability of the Soyuz in the future, did begin development of the X-38 CERV in 1997. The X-38 was however based on the Johnson concept of parachute-assisted landing, and used the pure-USA X-24 lifting body shape....

• 22 - Gatland, Kenneth, Manned Spacecraft, Macmillan, New York, 1968.
• 48 - Miller, Jay,, The X-Planes, Aerofax, Arlington, Texas, 1988.
• 152 - Houchin II, Roy and Smith, Terry, Quest, "X-20 (7 articles)", 1994, Volume 3, Issue 4, page 4.
• 158 - Peebles, Curtis, Spaceflight, "The Origins of the US Space Shuttle - 1", 1979, Volume 21, page 435.