X-23A rocketplane

Description:

• The X-23A, also known as the SV-5D, was designed to acquire data relating to lifting maneuverable reentry vehicles in support of several Air Force and NASA programs. The effort was under the auspices of project PRIME (precision recovery including maneuvering entry) and was part of the larger three-part START (spacecraft technology and advanced reentry test) program, 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 during re-entry of Earth′s atmosphere, including cross-range maneuvers up to 710 statute miles (1143 km) from the ballistic track.
• Under these programs, the same SV-5 lifting-body shape was tested at both extremes of its speed range—X-23A tested the very-high speed reentry phase; X-24A tested the low-speed landing characteristics. To study the effects of reentry on the ablative heat shield, the X-23A vehicle was intended to be recovered in mid-air by parachute.
• The X-23A represented a major step forward in understanding the requirements imposed by atmospheric reentry on a maneuvering vehicle. Additionally, information was gathered on the effectiveness of its ablative heat shield, and on the possibility of refurbishing such a heat shield for multiple uses. The information derived from the X-23A program assisted the designers of the Space Shuttle and various maneuvering warhead projects in determining their requirements.
• Four X-23As were manufactured, and three were launched using SLV-3 Atlas launch vehicles from SLC-3E at Vandenberg AFB, California. The first two vehicles were not recovered, but the third was and is currently on display at the Air Force Museum. There is no record of the disposition of the fourth vehicle.
• Design: Each X-23 was constructed from titanium, beryllium, stainless steel, and aluminium. 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 (¾ to 2¾ inches) thick, and the nose cap was constructed of carbon phenolic material.
  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 in midair by a specially-equipped JC-130B Hercules aircraft.

X-23A Credit: USAF

Technical Data: Manufacturer: Martin Marietta Corporation Operator: USAF Length : 6 ft 9 in (2.07 m) Heigh: 2 ft 1 in (0.64 m) Wingspanpan: 3 ft 10 in (1.16 m) Loaded weight: 890 lb (405 kg) Crew: None Power: Nitrogen gas reaction control thrusters Thrust: - Max speed Mach 25 Range 710 miles (1,143 km) Total Flights 3 First Flight 21 Dec 1966 Last Flight 19 April 1967

Preserved SV-5D X-23 PRIME subscale lifting body on display at the National Museum of the United States Air Force Dayton, Ohio USA.

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 Ocean.
• The second vehicle was launched on 5 March 1967. This flight simulated a 654-mile (1053-kilometre) cross-range reentry, and banking at hypersonic speeds. The recovery parachute deployed properly and was located by two of the deployed recovery aircraft. During an inspection fly-by of the descending parachute system it was seen that reefing cutters had failed to actuate. These cutters are on the harness suspending the vehicle from the parachute to ensure stability of the vehicle behind the JC-130B recovery aircraft during reel-in, and permit safely boarding the vehicle. As a result, the parachute and vehicle were allowed to descend to the sea. Subsequently, the vehicle separated from its flotation "balloon" in the rough seas and, with the parachute, sank before a nearby ship could arrive to retrieve it from the ocean.
• The final PRIME mission was flown on 19 April 1967, and simulated reentry from low Earth orbit with a 710-mile (1143-kilometre) 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 missions were carried out. The third X-23 is now on display at the National Museum of the United States Air Force at Wright-Patterson Air Force Base in Ohio.

External links:

• Youtube video: Prototype Arrival (PRIME/X-23), Unloading, Mating and Launch