RL10 derivative engines for the OTV

Abstract

Derivative RLIO engines can satisfy the main propulsion requirements far the Orbital Transfer Vehicle (OTV) while offering a low risk minimum cost development program. The RLlO Product Improvement Program (PIP) is producing the technology for improving this engine through addition of multi-mode thrust, high mixture ratio capability and extendible nozzles. These features which have already been proven in concept in the PIP when added to the proven RLlO capability and reliability make this engine an outstanding candidate for OTV propulsion. Subjective factors for reusable rocket engines, influenced by Pratt & Whitney gas turbine engine experience, provide insights into reliability, engine life, maintenance and health monitoring; often varying from seemingly obvious conclusions. The RLlO Product Improvement Program is being conducted by Pratt & Whitney under NASA's Lewis Research Center contracts NAS3-22902 and NAS3-24238. BACKGROUND reduce vehicle propellant tank weight, (2) efficiently utilizing propeliants used to condition (cooldown) the engine to operating temperature to reduce propellant consumption and (3) providing autogenous vehicle tank pressurization to eliminate vehicle pressurization systems. The low thrust capability which is required for effjcient cooldown and autogenous pressurization may also be operated in a sustained mode for dep.loyment of acceleration sensitive payloads. The OTV reusable engine requires health monitor capability to assure a mission is not initiated with a "sick" engine o r for shutdown of a malfunctioning engine in multiple engine installations. Extended engine life and modular construction for ease of maintenance are not OTV engine requirements but should be considered if cost effective. Subjective Considerations also influence the desirability of these features. Propulsion requirements for the OTV (and RLlO Derivative engines which satisfy OTV its predecessors such as the Orbit-to-Orbit requirements for both dual and single engine Shuttle and Space Tug) have been under investiinstallations follows. An advanced Pratt & gation for many years. A consensus is forming Whitney engine for the OTV is described in on the following: Reference 1. o The vehicle should use hydrogenlaxygen o The vehicle should utilize an aeroassist as Propellants.