Real-Time Flight Simulation of Highly Maneuverable Unmanned Aerial Vehicles

This paper focuses on full six degree-of-freedom aerodynamic modeling of small unmanned aerial vehicles at high angles of attack and high sideslip in maneuvers performed using large control surfaces at large deflections for aircraft with high thrust-to-weight ratios. Configurations, such as this, include many of the currently available propellerdriven radio-controlled model airplanes that have control surfaces as large as 50% chord, deflections as high as 50 deg, and thrust-to-weight ratios near 2:1. Airplanes with these capabilities are extremely maneuverable and aerobatic, and modeling their aerodynamic behavior requires new thinking because using traditional stability-derivative methods is not practical with highly nonlinear aerodynamic behavior and coupling in the presence of high prop-wash effects. The method described outlines a component-based approach capable of modeling these extremely maneuverable small unmanned aerial vehicles in a full six degree-of-freedom real-time environment over the full +/- 180 deg range in angle of attack and sideslip. Piloted flight-simulation results for four radio-controlled/unmanned-aerial-vehicle configurations having wingspans in the range from 826 mm(32.5 in.) to 2540 mm (100 in.) are presented to highlight the results of the high-angle aerodynamic modeling approach. Maneuvers simulated include tailslides, knife-edge flight, high-angle upright and inverted flight, rolling maneuvers at high angle, and an inverted spin of a biplane. For each case, the flight trajectory is presented together with time histories of aircraft-state data during the maneuvers, which are discussed.