Estimators for Angle of Attack and Angle of Sideslip of a Sailplane

Abstract

This paper describes a method for estimating angle of attack (AoA) and angle of sideslip (AoS) onboard sailplanes, using inertial and pressure measurements. The method is used to develop a hybrid AoA estimator combining lift-based and drag-based approaches that have been validated against flight test data. The approach eliminates the need for external sensors while maintaining acceptable accuracy during free flight. The remaining accuracy challenges in glider launch phases and in the vicinity of stall also are discussed. The proposed mathematical formulation relies on a minimum set of sailplane-specific coefficients, the evaluation of which also is documented. The expected benefit of the approach is to enable the estimators’ practical implementation for a sailplane instrument operated by pilots without specialist training.