OK, got it. I think we were all thinking the same things(TallPaul must be a LM guy? did I see you give a presentation to SAE 2 years ago at Palmdale on th SR-71?) Anyway, this is a great conversation.

The prospect for accurately measuring TAS allows a new approach to computing air data parameters that avoids the use of static pressure measurements and its associated measurement problems. Adding true speed to the measurement mix of total pressure (Pt), and total temperature (Tt), allows all other air data parameters to be calculated as follows:
Knowing the specific heat, Cp , for air and using the measured true speed and total temperature allows the calculation of ambient temperature, Ta :

CpTt = Cp Ta + ½ Vt2

from which the speed of sound, a , and Mach number, M, is evaluated as a=(gR Ta)1/2 and Mach number, M = Vt /a
Using the measured total pressure and the true speed or the calculated Mach number allows the calculation of atmospheric pressure and pressure altitude:

Pt/ Pa = (Tt/Ta)3.5 or = (1 + 0.2 M2 )3.5

Having the total pressure and temperature, ambient pressure and temperature and the Mach number all other air data parameters (Vc, Ve, et cetera.) can be calculated from standard air data equations.
If the true speed is corrected for flow inclination, which can be readily measured, the computed pressure is the free stream ambient pressure and is not subject to position errors that plague Pitot static based air data system measurements. This can be done through a simple cosine correction to the measured true speed, Vt

Vt = Vt cos è

where è is the angle between the measured true speed vector and the flight path velocity vector. Combining the true airspeed and GPS velocities allows the explicit computation of the instantaneous wind velocity and direction.


This method would be beneficial since static pressure wouldn't have to be measured! Would anyone be interested?