Dynamic Flight Simulation of Spanwise Distributed Electric Propulsion for Directional Control Authority

Abstract

A linear time-invariant state-space model was developed to simulate the six-degree-of-freedom aircraft dynamics of the Aircraft for Distributed Electric Propulsion Throttle-based Flight Control (ADEPT-FC), a 34 lb remote controlled aircraft featuring eight overwing electric ducted fans (EDFs) distributed spanwise along the wing's trailing edge. This model utilized parasite drag estimates from OpenVSP's parasite drag tool, trimmed stability coefficients from VSPAERO's stability coefficient solver, and mass properties measured from the as-built aircraft to populate the traditional vehicle dynamics portion of the model's state-space matrices. A second-order state-space frequency model of propulsor dynamics was developed and tuned to the frequency response of the Schübeler EDF as measured in wind-tunnel testing. The influence of propulsor thrust on the vehicle's dynamics was derived and superimposed into the vehicle dynamics state-space model, bridging the gap between a conventional vehicle's state-space model and the propulsor dynamics frequency models for each propulsor. This updated vehicle dynamics model can be provided both aircraft control surface deflections and propulsor thrust inputs to simulate the dynamic response of the vehicle. Without consideration of anticipated propulsion airframe integration (PAI) cross-coupling effects, the simulator developed herein suggested that asymmetric throttle mixing of the EDFs should provide a similar response to that of a rudder deflection. It is anticipated that addition of the PAI effects will magnify the roll rate associated with the maneuver, caused by thrust-induced lift over the outside wing. Further development of this technology could enable a reduction or elimination of the aircraft's vertical tail.