Evaluating the Probability of End-of-Life Failure-Free Performance of Liquid-Propellant Rocket Engine of Reusable Space Tug

A method is given for evaluating the probability of failure-free performance of the liquid-propellant rocket engine of a reusable orbital transfer vehicle (essentially a reusable "space tug") by the end of its operational life, taking into account that a probability of failure-free operation reduces with every start of the engine as its operational life draws to a close. The resulting expression allows one to estimate the probability of failure-free operation with consideration of design parameters of the propulsion system and the reusable space tug as a whole. It is found that for providing a high probability of failure-free performance of the propulsion system of a reusable space tug, it is more important to plan the larger margins of the engine service life and the number of its in-flight starts while designing than to achieve higher reliability through extensive testing at the stage of finishing.

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