Recommended Practice for Thrust Measurement in Electric Propulsion Testing

TLDR

Accurate, direct thrust or impulse measurement is critical yet difficult in electric thruster characterization. The paper reviews recommended practices for designing, calibrating, and operating pendulum thrust stands to measure micronewton‑to‑millinewton thrust and micronewton‑per‑second impulse bits. The authors review pendulum thrust stand fundamentals—including hanging, inverted, and torsional balance configurations—along with calibration procedures, error sources, and data processing for uncertainty analysis.

Abstract

The accurate, direct measurement of thrust or impulse is one of the most critical elements of electric thruster characterization, and it is one of the most difficult measurements to make. This paper summarizes recommended practices for the design, calibration, and operation of pendulum thrust stands, which are widely recognized as the best approach for measuring micronewton- to millinewton-level thrust and micronewton-per-second-level impulse bits. The fundamentals of pendulum thrust stand operation are reviewed, along with the implementation of hanging pendulum, inverted pendulum, and torsional balance configurations. The methods of calibration and recommendations for calibration processes are presented. Sources of error are identified, and methods for data processing and uncertainty analysis are discussed. This review is intended to be the first step toward a recommended practices document to help the community produce high-quality thrust measurements.