The effect of a wind gradient on the rate of climb of an aircraft

Abstract

The behaviour of an aircraft climbing in the presence of a wind gradient is analysed by a method similar to that used in R. & M. 379, but with fewer simplifying assumptions. It is shown that the result obtained in the earlier paper is only correct if the angle of climb is small and if the true air speed is constant during the climb. With the climb techniques that are now usual, however, the true air speed is not constant during the climb; with typical subsonic aircraft the effect of this is to change the correction due to a wind gradient by about 10 per cent. For aircraft climbing at supersonic speeds the effect of acceleration may be much greater than this. Since the percentage change of rate of climb due to a given wind gradient is approximately proportional to the flight speed, the effect does not become less important as aircraft speeds increase. Moreover, wind gradients having a significant effect on the rate of climb are not confined to low altitudes. For a modern high-speed aircraft it is shown that the wind gradient may change the rate of climb by 20 per cent or more.