Advanced cryogenic solid hybrid rocket engine developments: concept and test results

ORBITEC has conducted considerable R&D under various USAF and NASA contracts and company sponsored efforts to develop a new class of rocket propulsion devices, cryogenic solid rocket engines The basic concept of these engines is to freeze a propellant which is normally a gas at room temperature into a solid propellant grain. This solid grain is then combusted with a second propellant These rocket engines promise a number of advantages over conventional liquid rocket engines, including increased simplicity, safety, propellant density, and potentially performance with the addition of High-Energy Density Matter (HEDM's). ORBITEC has tested cryogenic solid hybrid rocket engines including the following propellant combinations: (1) solid oxygen/gaseous hydrogen; (2) solid hydrogen/gaseous oxygen; (3) solid methane/gaseous oxygen; and (4) solid methane-aluminum/gaseous oxygen. The primary focus of this paper is on solid oxygen/gaseous hydrogen. Work achieved to date includes: (1) a total of over 50 solid oxygen test firings; (2) establishment of regression rate data for the different propellant combinations, where the rates can be a factor of 20 to 40 times higher than conventional HTPB-based hybrids; (3) achievement of burn durations from 1 to 30 seconds; and (4) engine chamber pressures as high as 250 psi The potential applications include. research devices to test high-energy density matter (HEDM); hybrid rocket launch vehicle upper stages; or orbit transfer vehicles. During a current sponsored USAF Research Laboratory (RL, Edwards Air Force Base, CA) project, ORBITEC is to design, develop and test a larger, SOX/LH2 flight-type engine that will have throttling and O/F ratio control.