Patent ID: 6176130
Filing Date: 2001-01-23
Classification: G01P

Abstract:
A flight velocity vector measuring system in a wide velocity region comprising:a primary calculation process in which five pressure information items detected by a truncated pyramid-shape probe, in which an extreme end has a truncated pyramid-shape and a pressure hole is provided in each square truncated pyramid surface, are converted into electric signals and incorporated into a calculation processor, an attack angle pressure coefficient C.alpha. of air current and a sideslip angle pressure coefficient C.beta. are obtained from pressure differential information of upper and lower holes of said probe and pressure differential information of left and right pressure holes, respectively, and an air current angle pressure coefficient C.gamma. is obtained from the attack angle pressure coefficient C.alpha. of air current and the sideslip angle pressure coefficient C.beta. thus obtained; anda secondary calculation process in which the attack angle pressure coefficient C.alpha., the angle pressure coefficient C.beta. and the air current angle pressure coefficient C.gamma., pressure calibration coefficients with respect to a Mach number M, an attack angle .alpha. and a sideslip angle .beta. every velocity region obtained by dividing the wide velocity region into a plurality of regions stored in advance in the calculation processor, and a Mach number M, an attack angle .alpha. and a sideslip angle .beta. of unknown quantity constitute a calculation processing expression comprising a polynomial approximation to decide the magnitude of the Mach number M, subsequently decide the velocity region by the Mach number M obtained, said pressure calibration coefficients in said velocity region are called, and a flight velocity vector (m, .alpha., .beta.) is calculated by said polynomial approximation,wherein the wide velocity region is divided into three velocity regions consisting of: (1) a velocity region in which the Mach number M is less than 0.2; (2) a velocity region (0.2. M<1.0) from subsonic to a Mach number M of 1.0; and (3) a velocity region in which the Mach number M equals 1.0 or more and an attack angle calibration coefficient table, a sideslip angle pressure calibration coefficient table, and a Mach pressure calibration coefficient table are prepared for every velocity region and stored in a ROM of said calculation processor.