SpaceDev is to provide the hybrid rocket motor for Scaled Composites' manned suborbital spaceship demonstrator and contender for the $10 million X-Prize. The SanDiego-based company was selected over Environmental Aerospace (EAC) to supply motor components for the SpaceShipOne flight-test phase, which could begin before year-end.
Miami-based EAC and SpaceDev each completed six ground firings of their hybrid rocket engines, which use pressure-fed nitrous oxide as the oxidiser and hydroxy-terminated polybutadiene as the solid fuel. SpaceDev began tests with a 15s firing in November last year, and completed testing with a full-duration 90s run in July.
Scaled says its all-composite design allows the propulsion system to be mounted to the air-launched SpaceShipOne by simple skirt flanges on the oxidiser tank, with the fuel-case and nozzle cantilevered to the tank. The Mojave, California-based company will produce both the oxidiser tank and unitised case/nozzle in-house, and deliver them to SpaceDev for assembly and fuelling of the motor. The tank will have a composite liner laid up on titanium flanges, with a carbonfibre over-wrap provided by Thiokol. The case/nozzle uses a high-temperature composite insulator with a carbonfibre/epoxy structure laid up on an ablative nozzle supplied by AAE Aerospace.
SpaceDev will supply the ignition system, main control valve, injector, electronic controls and fuel casting. Whereas EAC's hybrid motor had one central port through which the oxidiser was pumped, SpaceDev says its design has four combustion cavities running through the fuel to increase the surface area and produce the required thrust. EAC was selected in June to supply the nitrous oxide fill, vent and dump system.
Source: Flight International
