Uncertainty in Inverted Pendulum Thrust Measurements

Mackey, Jonathan A ; Haag, Thomas W ; Kamhawi, Hani ; Hall, Scott J ; Peterson, Peter Y

关键词: ELECTRIC PROPULSION;    PENDULUMS;    THRUST MEASUREMENT;    BIAS;    CALIBRATING;   

RP-ID  :  NASA/TM-2018-219952,E-19563,GRC-E-DAA-TN59050

学科分类：航空航天科学

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来源: NASA Technical Reports Server

【 摘 要 】

An uncertainty analysis of a common configuration of electric propulsion thrust stand is presented. The analysis applies to inverted pendulum thrust stands operating in a null-coil configuration with in-situ calibration. Several sources of bias and precision uncertainty are discussed, propagated, and combined to form conservative estimates of the relative and absolute thrust uncertainties. A case study of the NASA Glenn Research Center Vacuum Facility 6 thrust stand is presented. For the thruster investigated, the uncertainty was estimated to be ±6.9 mN over the entire span of thrust. This uncertainty represents a maximum instrument bias introduced by the thrust stand. The paper does not address repeatability of actual thrust measurements, as this is generally beyond the influence of the thrust stand and can be dependent on a large number of factors.