NASA failed to attract industry co-investment to develop the original X-34A air-launched, reusable, low-technology, low-cost orbital launch vehicle concept. So the project was scaled back and NASA contracted with Orbital Sciences on 28 August 1996 to build and fly the X-34 unmanned technology demonstrator. This program in turn developed overruns and was cancelled in 2001 before a test flight was made.

Objectives of the X-34 program were to demonstrate new, efficient vehicle processing and launch operations and evaluate the performance of advanced reusable launch vehicle technologies. The program was to demonstrate a nominal two-week turnaround between flights, and a surge capability of two flights within 24 hours. The single stage vehicle used NASA’s low cost Fastrac engine for liquid oxygen/kerosene propulsion. The vehicle itself used all-composite primary and secondary structure. Its autonomous flight control system was to make automated approach and landings. Flights were planned to speeds of Mach 8 over an 800 km range. The original 1996 contract with Orbital Sciences covered construction of three flight vehicles and 26 powered and unpowered flights launched from an L-1011.

NASA rolled out the first unpowered aerodynamic flight test vehicle in April 1999 and conducted captive-carry flights from the L-1011 later in the year. By July 2000 the vehicle was being towed by a truck down the runway at Edwards. Before it could become airborne, a NASA review of the project indicated costs continued to rise beyond budget, and that the benefits to be derived from continuing the program did not justify the cost. The X-34 was cancelled, together with the X-33, on 1 March 2001.

The X-34A's drop weight of 21,800 kg included 13,600 kg of propellant. Investment in the project before cancellation included the original $85.7 million contract with Orbital Sciences; $16 million from NASA and other government agencies for wind tunnel testing, thermal protection systems, vehicle health monitoring, ground support, engine testing and flight support; $ 10 million in Orbital corporate funds for modifications to its L-1011 carrier aircraft to accommodate the X-34. NASA’s Marshall Space Flight Center managed the program; and Marshall expenses to develop the Fastrac engine.

Key technologies planned for demonstration on the X-34 were: lightweight composite airframe structures that required little inspection; reusable composite propellant tanks, tank insulation and other propulsion components; advanced thermal protection systems capable of surviving subsonic flights through rain and fog; integrated (built-in) low-cost avionics, including differential Global Positioning System and Inertial Navigation System; integrated automated vehicle health monitoring and checkout; and a conformal air data system for flight control inputs that would replace traditional blade-like air data probes, unable to survive reentry temperatures.

At one point a heavier, X-34B, which would be launched by a 747, was proposed. This presumably would have been a version of the original design, capable of releasing an upper stage to take a payload to orbit.

Manufacturer: OSC. Payload: 400 kg (880 lb). to a: Mach 8, 76 km trajectory. trajectory. Liftoff Thrust: 386.000 kN (86,776 lbf). Total Mass: 34,000 kg (74,000 lb). Core Diameter: 3.05 m (10.00 ft). Total Length: 26.00 m (85.00 ft). Flyaway Unit Cost $: 3.000 million. in: 1985 unit dollars.

• Stage Number: 1. 1 x Stage: X-34. Gross Mass: 21,800 kg (48,000 lb). Empty Mass: 8,200 kg (18,000 lb). Thrust (vac): 268.927 kN (60,457 lbf). Isp: 310 sec. Burn time: 150 sec. Span: 8.54 m (28.01 ft). Length: 17.68 m (58.00 ft). Propellants: Lox/Kerosene. No Engines: 1. Engine: Fastrac. Status: Development ended 1996. Low cost reusable vehicle technology demonstrator.