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300-LB(f) Monopropellant Hydrazine Thruster Life Evaluation

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Final rept. 1 Nov 1971-30 Apr 1972

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There was a primary need to demonstrate the extended life capability of a nominal 300-lbf monoPropellant hydrazine thruster beyond qualification limits. In addition, there were secondary needs to attain end of life performance characteristics first to verify a catalyst bed pressure drop buildup theory of performance degradation, and second to test a casual theory for the occurrence of washout performance degradation. The program documented herein takes three steps toward the fulfillment of these needs by conducting life tests on three thrust chambers, two which already had specified mission life accumulated and one which was refurbished to the as new condition. All three units tested demonstrated extended life capability, but each provided performance characteristics which reflected the particular type of duty cycle conducted. The unit which produced high catalyst bed pressure drop also produced higher than usual in-run manifold temperature. The other two units produced low catalyst bed pressure drop buildup and consequently attained a longer unencumbered life characteristic. Based upon these results, it is concluded that extended life capability is demonstrated and the secondary need to verify catalyst bed pressure drop buildup theory was accomplished. However, washout performance characteristics were never accomplished preventing the accumulation of convincing data to support the causal theory. Recommendations based upon these findings include investigation and elimination of variability in sensitive build parameters, life testing to verify elimination of variability as well as obtain end of life data, and the determination of safe in-run and shutdown manifold temperature on high catalyst bed pressure drop units.

Subject Categories:

  • Liquid Propellant Rocket Engines
  • Liquid Rocket Propellants

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