A Method to Calculate Uncertainties of Drag Coefficient Wind Tunnel Data

摘要

A method to calculate wind tunnel drag coefficient uncertainty for a point on a fitted lift-drag curve is developed. The total uncertainty is shown to consist of two parts; that associated with the measurement process and that due to the curve fit. Equations to combine the two sources of uncertainty are presented, and a general method is given to calculate the part caused by the curve fit process. Because measurement uncertainties depend on the test facility and instrumentation, only general guidelines are presented to account for this contribution. A computer program to calculate drag uncertainty is included. Program equations for measurement uncertainty are based on the AEDC Tunnel 4T.