Accuracy and Best Practices for Small-Scale Rocket Engine Testing

Abstract : An in-depth analysis of the uncertainties associated with small-scale rocket engine testing has been conducted. The analysis uses terminology and approaches detailed in the ISO ?Guide to the Expression of Uncertainty in Measurement? (GUM) and a recent NASA handbook on the subject (NASA HBK-8739.19-3). Along with this analysis, best practices for minimizing uncertainties are provided. AFRL?s Experimental Cell-1 facility is used as the example engine, and the data values provided come from this system. The facility is sized to test a single, full-scale element or an array of scaled-down elements producing thrust in the range of 100-500 pounds. The facility has recently completed an overhaul to increase the number of data channels available and to improve accuracy. The measurand being specifically evaluated is c*-efficiency (ηc*). However, details are given on all of the parameters which contribute to the measurement and calculation of this value. This analysis should aid in the design, upgrade, operation and data assessment of EC-1 and other small-scale facilities.