Aero-Propulsive Modeling for Propeller Aircraft Using Flight Data

Abstract

This paper describes methods to identify an integrated propulsion–airframe aerodynamic model and a decoupled propulsion model for fixed-wing aircraft with propellers using flight data. Propulsion aerodynamics and airframe aerodynamics for propeller aircraft are usually modeled separately, which fails to describe unavoidable interaction effects and propeller performance deviations when integrated on an aircraft. Two novel flight test system identification approaches are presented to develop flight dynamics models with improved characterization of propeller aerodynamics compared to conventional methods. Orthogonal phase-optimized multisine inputs are applied to both the control surfaces and propulsion system to generate data with high-quality information content for model identification. Propulsion explanatory variables derived from propeller aerodynamics theory combined with traditional aircraft modeling variables yield accurate aero-propulsive modeling results and provide propeller performance estimates, which are compared to isolated propeller wind tunnel data. An assessment of model adequacy using flight maneuvers withheld from model identification indicates that the models have good prediction capability. The paper describes application of these methods to a small unmanned aircraft, but the methods are generalizable to many propeller-driven aircraft.