Static Source Error Calibration of a Nose Boom Mounted Air Data System on an Atmospheric Research Aircraft Using the Trailing Cone Method

Abstract

This work demonstrates the calibration of an experimental air data probe on an atmospheric research aircraft by means of the Trailing Cone method. The probe under investigation is located on a nose boom in order to minimize the aerodynamic influence of the fuselage on the pressure measurement ahead of the aircraft. However, the data from this experiment proves that this configuration is still subject to significant pressure deviations from the undisturbed atmospheric values. This work demonstrates the determination of this error and presents an appropriate parameterization of the data which is prerequisite to provide accurately corrected pressure readings from this sensor. The experiment covers the determination of the proper configuration (length) for the Trailing Cone assembly, the validation of the method itself and the subsequent calibration of the air data sensor. Several improvements were applied to the Trailing Cone method in order to reduce the flight test effort as well as to significantly enhance the accuracy of the method itself. As a consequence a total of only three test flights was necessary to validate the method and to calibrate the air data sensor. The data analysis shows that the accuracy of the Trailing Cone reference measurement is very close to the pressure sensor calibration limit of 0.1hPa. The resulting accuracy of the corrected pressure measurement by the nose boom mounted pressure probe was demonstrated to be about 0.2 hPa, which represents the 3σ value.