Engineering topics
Publications and source records attributed to Estey, P. N..
Pumping system has lower mass. Equations worked out to compare masses of pump and pressure-fed bipropellant propulsion systems. Equations developed specifically for interplanetary spacecraft but technique adaptable to advanced automative energy-storage techniques.
An analysis of the time response of a propellant supply system operating in the blowdown mode is presented. The supply system is part of a pump-fed propulsion system intended for use on interplanetary spacecraft. As such, the supply system must provide the pump with propellant at sufficient pressure to avoid pump cavitation. The system, consisting of the tank, the liquid propellant, the pressurant gas and propellant vapor mixture, and a film layer separating the liquid and vapor phases, is analyzed using the principles of mass and energy conservation. The resulting set of ordinary, coupled, nonlinear differential equations for the thermodynamic state variables is integrated as an initial value problem. The resulting histories of total pressure, propellant vapor pressure, propellant liquid temperature, film layer temperature, propellant vapor/pressurant gas temperature, propellant vapor mass, and propellant liquid mass enable the calculation of the net positive suction head available at the pump which determines the viability of the pump-fed system concept when operated in the blowdown mode.
A study has been conducted to select the most desirable pump-fed propellant feed system approach for planetary spacecraft. Four systems, including two battery powered and two gas generator driven systems, were considered. Complete propulsion system schematics were developed, including preliminary detailed design of both the electric motor and the gas turbine pump drives. Utilizing a Figure-of-Merit system which included consideration for reliability, development risk, complexity and growth potential as well as weight, the advanced battery powered electric motor drive system was selected for continued development at JPL.