In the past several years there have been many attempts at developing a low-cost liquid or hybrid space launch size propulsion system. All of the systems share a common flaw in the lack of a reasonable and believable liquid feed system. When designing even small space launch systems the trade-off between heavy pressurized tanks verses the more traditional turbo pump feed systems with light weight propellant tanks, the choice has always been dictated by System cost rather than performance. Various clever schemes such as heated helium have been employed to pressurize liquid feed tanks, however none of these systems have proved workable in large-scale weight requirements or demonstrated flights. It as occurred to us that the development of a truly low-cost and simple turbo pump liquid feed system for both storable and cryogenic propellants could facilitate the development of several low-cost launch system designs. A low cost turbopump fed system integrated into hybrid propulsion designs offers many of the inherent advantages of hybrid motors such as improved storage, deployment and long term stability. Because the oxidizer is stored separately from the fuel component until use, the need to compound the oxidizer with the appropriate fuel/binder system is eliminated. In addition, mass fraction is improved by eliminating high-pressure tanks and pressurization systems. Such a system could also incorporate temperature-sensing devices at the fuel/case insulation interface that could initiate a controlled burn termination sequence. This could reduce case insulation requirements and further improve mass fraction.
