Drift Due to Engine Torque: Some Reasons for Reconsideration of the Conclusions Arrived at by Wing Commander Wackett

IN an article on this subject, published in the February issue of Aircraft Engineering this year. Wing Commander L. J. Wackett suggests that an aeroplane must fly at an appreciable angle of yaw in order to counteract the torque of the engine and airscrew. He gives an approximate formula for calculating this angle of yaw, and describes a series of experiments which appear to confirm his calculation. Since the angle of yaw suggested by this investigation is surprisingly large and would have serious effects on navigation and gunnery, I have made a closer examination of the problem. This analysis has led me to doubt the validity of Wing Commander Wackett's conclusions, since the calculated angle of yaw is negligibly small if the torque is balanced by use of the ailerons and if the aeroplane is maintained on a level keel.