eder@ssc-vax.UUCP (Dani Eder) (09/14/88)
(1) The Space Shuttle Main Engine is not designed to run below 65% of its rated thrust (470,000 lb in vacuum). This is a consequence of it's complex 'staged combustion' cycle (there are 3 combustion chambers, the main one and one each for the high pressure fuel and oxidizer pumps). (2) It would be difficult to provide the right inlet pressures to the low pressure fuel and oxidizer pumps. The inlet pressures consist of the pressures in the respective tanks plus (height derived pressure head times number of g's acceleration). This varies over the Shuttle launch. Even using one SSME at lowest setting, you have 300,000 lb of thrust, which is more than a 747 during takeoff. A bit much for a 'scooter'. There might be a useful engine to be gotten by scavenging one of the pump combustion chambers and adding a new noxxle to it. You would get away from having to 'balance' the full engine cycle, and might be able to run a full vairiable thrust engine. The previous author is correct in thinking that the Orbital Maneuvering System pods owould be usef~rul as small propulsion units. -- Dani Eder / Boeing / Space Station Program / uw-beaver!ssc-vax!eder (205)464-4150(w) (205)461-7801(h) 1075 Dockside Drive #905 Huntsville, AL 35824 34 40 N latitude 86 40 W longitude +100m altitude, Earth