RESEARCH ON THE SOLVING ACCURACY FOR THE FADS SYSTEM APPLIED TO THE VEHICLE WITH BLUNT FORE-BODIES

This paper studies the implementation and the accuracy of the FADS (flush air data sensing) system applied to the vehicle with blunt fore-bodies. For the 15° blunt fore-bodies at Mach number Ma = 2.04, 3.02, 5.01, angle of attack α is between -5° and 25°, and without the consideration of the angle of sideslip, the FADS model is a compromise between a simple potential flow model and the modified Newtonian flow theory. In this paper, the algorithm for the angle of attack based on the triple algorithm is developed, and the calibration error for the angle of attack is determined by the least-squares curve fitting. The free stream pressure and the dynamic pressure can then be determined by an iteration algorithm. Finally, the Mach number can be computed by using the normal one-dimensional fluid mechanics relationships. Systematic comparisons are conducted and it is shown that the model is reliable and the accuracy is high for the FADS system. The error for the angle of attack is less than 0.1°, the error for the free stream pressure is less than 5%, and the error for the Mach number is less than 0.01.