Predicting the contribution of running propellers to aircraft stability derivatives

Running propellers can have a profound effect on the trim and static stability of an airplane. The method most commonly used for determining propeller stability derivatives is based on blade element theory with the axial component of induced velocity taken to be that predicted from classical propeller momentum theory. The induced flow predicted from propeller momentum theory is not consistent with the actual induced flow in the vicinity of a rotating propeller. In the present paper an alternative method for predicting propeller stability derivatives is proposed. This method is based on blade element theory with the induced velocity predicted from propeller vortex theory. Results are compared with other analytical predictions and experimental data for specific propeller blade geometry.