Airspeed estimation using servo current and aircraft model

This paper presents a model-based technology for estimating the airspeed of an aircraft. It requires a dynamic model of the aircraft and a measurement of a signal which correlates with the wind load such as the servo current. The performance of the airspeed estimator is evaluated against modeling errors such as uncertainties in aircraft weight and c.g. configuration and errors in the control surface hinge moment coefficients. Simulation experiments show that the airspeed estimation error is comparable with that of a pitot tube for low-mid wind levels (~25-50 knots) with an uncertainty in the aircraft weight up to 19% and in the c.g. location up to 16%, and with typical errors in the control hinge moment coefficients. The estimation error increases by a factor of two for high levels of wind (~100 knots).