Investigation of Pilot-Induced Longitudinal Oscillation in the Douglas Model A4D-2 Airplane

A stability analysis of the pilot-induced longitudinal oscillations on the Model A4D-2 is presented. Figures of merit for analyzing the system are chosen and numerous parameter variations are made to determine what can eliminate the oscillations. It is shown that the control system moment of inertia and the distance from the aircraft C.G. to the bob-weights can be selected to increase system stability. The revised control system which was considered suitable for the Board of Inspection and Survey trials is analyzed and is shown to have very favorable dynamic characteristics compared to the original system.