Load Envelope Analysis of Strain-Gage Balance Data

A load envelope analysis process was developed for strain–gage balance data. The process compares wind tunnel test loads with balance calibration loads in order to identify calibration load envelope outliers. The process uses electrical responses from all calibration points, electrical responses from wind tunnel test points, and the data reduction matrix of the balance as input. Then, after calculating calibration and wind tunnel test loads from the responses, plots of all possible gage load combinations are used to display the calibration load envelope and to highlight possible load envelope outliers. Two criteria are applied to identify load envelope outliers. The first criterion compares individual loads of a data point with the corresponding calibration load range. The second criterion compares load combinations of a data point with load combinations that were applied during the balance calibration. A six–component balance example is used to illustrate benefits of the new load envelope analysis process.