Low-Cost Hardware for In-Space Oxygen/Hydrogen Propulsion, Phase II

The use of gaseous oxygen/hydrogen (O2/H2) propellant for satellite maneuvering, attitude control, and station keeping offers many advantages over the use of storable propellants such as nitrogen tetroxide/monomethyl hydrazine (NTO/MMH) or nitrogen tetroxide/hydrazine (NTO/N2H4). Primary among these are increased specific impulse and reduced launch weight. Previously, the use of gaseous O2/H2 was limited by the lack of a combustion chamber material capable of withstanding the temperatures of stoichiometric O2/H2 combustion. Ultramet recently solved this problem by demonstrating a material system capable of operating for several hours under stoichiometric conditions utilizing only radiation cooling. Because the chambers reached temperatures of nearly 2600?C during testing, a water-cooled injector was used. That will not be an option in space, so an injector must be developed that will be able to withstand these extreme temperatures and minimize thermal soakback to the valves. In Phase I, an uncooled combustion chamber/injector system for use with stoichiometric O2/H2 propellants was designed, fabricated, and hot-fire tested. Phase II will focus on improving the life of the combustion chamber by taking a critical look at the designs of both the chamber and the injector. Modifications will be made, and several iterations of hot-fire testing will be performed. Based on previous hot-fire testing with this material system, it is anticipated that lifetimes in excess of ten hours can be achieved.