Patent ID: 7461548
Filing Date: 2008-12-09
Classification: G01P

Abstract:
1. A method of obtaining the three components u, v, and w of the air speed along a trajectory TA of an aircraft in a non-rotary rectangular frame of reference (x,y,z) , characterized by the following steps: a) measuring air pressures via at least four pressure intakes P b) converting the four pressure measurements into four electric signals; c) establishing a first magnitude S by adding the electric signals obtained from the two pressure intakes P d) establishing a second magnitude D by adding the electric signals obtained from one of the two pressure probes and by subtracting the electric signals obtained from the other pressure probe; e) using a Taylor/MacLaurin series development of the theoretical expression for the tangential speed TB of the air in register with each pressure intake and retaining only the first order terms so as to obtain firstly a first expression representative of the first magnitude S and secondly a second expression representative of the second magnitude D having the following forms respectively: where: ρ=density of air; U=the driven speed of the probes in the rotary movement of the arm ( =−ΩR ; v v v f f f f) since the first expression S is proportional to w, and since the other terms are known, deducing w therefrom by identifying said first expression S with the first magnitude S, said operation being performed by harmonic analysis synchronized on the speed of rotation of the arm ( g) since the second expression D is a periodic function of time due to the constant speed of rotation Ω of the arm and depends on two periodic components v