Martin X-23 PRIME

Martin Marietta's X-23A PRIME (Precision Reentry Including Maneuvering reEntry) was a small lifting body re-entry vehicle tested by the United States Air Force in the mid-1960s. Unlike ASSET, primarily used for structural and heating research, the X-23 PRIME was developed to study the effects of maneuvering re-entry, including cross range maneuvers up to 710 miles (1143 km) off the ballistic track.

Design

Each X-23 was constructed from titanium, beryllium, stainless steel, and aluminium "where appropriate". The craft consisted of two sections - the aft main structure and a removable forward "glove section". The structure was completely covered with a Martin-developed ablative heat shield 20 to 70 mm (0.8 to 2.75 inches) thick, though the nose cap was constructed of Carbon-Phenolic.

Aerodynamic control was provided by a pair of 12-inch (30 cm) square lower flaps, and fixed upper flaps and rudders. A nitrogen gas reaction control system was used outside the atmosphere. At Mach 2 a drogue ballute deployed and slowed the vehicle's descent. As it deployed, its cable sliced the upper structure of the main equipment bay, allowing a 47-foot (16.4 m) recovery chute to deploy. It would then be recovered by a specially-equipped JC-130B Hercules.

Flight testing

The first PRIME vehicle was launched from Vandenberg AFB on 21 December 1966 atop an Atlas launch vehicle. This mission simulated a low-earth orbit reentry with a zero cross-range. The ballute deployed at 99,850 feet (30.43 km), though the recovery parachute failed to completely deploy. The vehicle crashed into the Pacific.

The second was launched on 5 March 1967. This flight simulated a 654-mile (1053 km) cross range re-entry, and banking at hypersonic speeds. Several stringers on the main parachute failed to cut, preventing a successful recovery. It too was lost in the Pacific.

The final PRIME mission was flown on 19 April 1967, and simulated reentry from low-earth orbit with a 710 mile (1143 km) cross-range. This time, all systems performed perfectly, and the X-23 was successfully recovered. An inspection by a USAF-Martin team reported the craft "ready to fly again", although no later mission was carried out. The third X-23 is now on display at the National Museum of the United States Air Force at Wright-Patterson Ohio.

Specifications (X-23)

General characteristics

• Crew: None

Performance

• Hypersonic L/D Ratio: 1:1

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