Abstract:

Regarding real gases as perfect gases approximately, the authors find the relationship between the true Ma number, true airspeed and total temperature. Using GPS ground speed, the true airspeed is calculated by “go and back flight test” to eliminate the influence of wind speed, and then the true Ma number is obtained. The “GPS speed method” is produced. Or, considering the difference of real atmosphere from standard atmosphere, one can introduce the pressure altitude constant deflection and the flight path pressure calibration coefficient in level lines, and establish the relationship between the true pressure altitude and geometrical altitude in flight airspace. Combining the correctional increment, which has been obtained by “GPS speed method” on any Ma number point, one can calculate the true pressure altitude and produce “GPS altitude method”. By flight test on XX aircraft, the reliability and practicability of these methods are shown.

Key words: pitot -static calibra tio ns, GPS, flight -test metho d