DESIGN OF A SUBSONIC FADS SYSTEM AND FLIGHT TEST EVALUATION

In allusion to the high precision requirements for flight parameters, a subsonic Flush Air Data Sensing(FADS) system was developed and flight tested. First of all, the FADS pressure data was built based on Computational Fluid Dynamics(CFD) modeling, and error distribution bounds for pressure inputs was analyzed based on CFD modeling accuracy and wind tunnel calibration data. Secondly, real-time solution algorithm based on the surrogated model was analyzed and principle prototype was implemented. Finally, flight test were implemented to validate the FADS principle prototype. In order to evaluate the reliability of the real-time FADS angle of attack solving algorithm in flight test validation, the angle of attack solving algorithm based on the aerodynamic model was rebuilt afterwards. Systematic comparisons for angle of attack between FADS system and INS were determined. The results show that similar results are obtained from aerodynamic model and surrogated model, and the reliability. of angle of attack real-time solving algorithm is validated during flight test. Accuracy of real-time angle of attack solving algorithm is less than 1°, and even less than 0.5°during the key flight phase. Pressure inputs fluctuated abnormally exceeding error distribution bounds is the main factors caused the angle of attack data abnormity. The FADS solving algorithm determined by CFD modeling technology can set a allowable pressure inputs error bounds, and reasonable fluctuated pressure inputs have no influences on angle of attack. Therefore, angle of attack data abnormity is caused by pressure inputs fluctuated abnormally exceeding error distribution bounds. For the FADS system applied to a subsonic vehicle, pressure transducer accuracy and fine engineering implementation is necessary for high precision solution.