A Simplified Model for Propeller Thrust in Oblique Flow

Abstract

New aircraft architectures are being proposed for unmanned aerial vehicles and air taxis, which include tilt-able motor and propellers. These propulsive units operate with a propeller axis at an angle oblique to the flight direction, and thus it is important to understand and model how thrust is produced by a propeller operating under these conditions. Propellers in oblique flow have been modeled using Blade Element Momentum Theory coupled to an inflow model, and the Vortex Lattice Method. In the present work, we develop a much simpler approach that neglects the crossflow component of the incoming air velocity. An advance ratio is developed based on the parallel inflow component, and is coupled to existing propeller data collected in axial flow conditions. The proposed model is evaluated using existing experimental data collected under oblique flow conditions, and is predicts thrust to within \(5\,\%\) of experimental values for most conditions. The greatest discrepancy between the model and experiments occurs in the pure crossflow case, which is of lesser importance in the application to unmanned aerial vehicles and air taxis.