Discrepancies between the model and balance coordinate systems can lead to biases in the aerodynamic measurements during wind-tunnel testing. The reference coordinate system relative to the calibration coordinate system at which the forces and moments are resolved is crucial to the overall accuracy of force measurements. This paper discuses sources of discrepancies and estimates of coordinate system rotation and translation due to machining and assembly differences. A methodology for numerically estimating the coordinate system biases will be discussed and developed. Two case studies are presented using this methodology to estimate the model alignment derived from calibration data obtained from different calibration systems. Examples span from simulated angle measurement system and position shifts of a calibration system to discrepancies in actual calibration data. The results from these case-studies will help aerodynamic researchers and force balance engineers to better detect and diagnose potential differences in calibration systems due to coordinate system rotation and translation. This methodology is unique that it detects misalignments based on multiple datasets, not relying on quality-assurance measurements.
展开▼
