Over the next four years an X-vehicle airframe design for a future reusable launcher will be ground tested under the US Air Force Research Laboratory's $70 million Fully Reusable Access to Space Technology (FAST) programme.

The airframe testing is to be supplemented by work on vehicle subsystems and also propulsion options analyses, which could see future use of Space Exploration Technologies' (SpaceX) new Merlin engine. Ground-based experiments will include high-temperature ascent and re-entry testing with realistic aerodynamic loads.

The goal of FAST is to develop technologies for aircraft-like space access operations and to spin those out to the private sector while delivering on the objectives for AFRL's Operationally Responsive Spacelift military programme.

The ORS X-aircraft concept is a 13,600-27,200kg (30,000-60,000lb) vehicle capable of vertical take-off and horizontal landing, reaching low-Earth orbit using liquid oxygen and RP-1 grade kerosene or methane rocket power, with engine-out and full-envelope abort capabilities.

Future work might see a FAST-2 demonstrator launched by a SpaceX Falcon 9 or Orbital Sciences Minotaur rocket for a Mach 12 to M20 test flight.

The current FAST2C demonstrator design is 13.7m (45ft) long, using two of Challenge & Space's Chase-10 engines, has a dry mass of 7,200kg and gross lift-off weight of 27,200kg. It has a hot structure using carbon-carbon for much of its thermal protection system, with carbon silica nose panels.

A second design, which uses four SpaceX Merlin engines and is designated FAST4M, is about 18.3m long and has a dry weight of 13,000kg, similar to a Boeing F-15E. However, the maximum take-off gross weight would be 100,000kg.

AFRL spaceplane to begin trajectory trials

Space launch Initiative

Source: Flight International