Mechanisms of Aerodynamic Interference in a Dual-Propulsion Gyrodyne Unmanned Aerial Vehicle

Aerodynamic interference between multiple propulsion systems can strongly affect the performance of unconventional Unmanned Aerial Vehicles (UAVs). This study investigates the interaction between a front tractor propeller, an upper lifting rotor, and the airframe of a dual-propulsion gyrodyne UAV using unsteady Reynolds-averaged Navier–Stokes simulations with moving meshes. Two representative operating conditions are considered: powered forward flight, with the upper rotor operating in autorotation, and hovering, with the upper rotor providing lift. In forward flight, the propeller slipstream modifies the local incidence and dynamic pressure over the wing, producing an asymmetric spanwise lift distribution. The addition of the autorotating upper rotor further redistributes the wing loading through its interaction with the propeller slipstream and increases the total drag coefficient by approximately 3.7% relative to the propeller-only configuration. In hovering conditions, the rotor downwash strongly modifies the aerodynamic loading of the wing, with the interaction becoming negligible for rotor–wing separations, h/R≥0.6, for the investigated configuration. Overall, the results show that the aerodynamic loads of the complete configuration cannot be directly inferred from those of the individual propulsion systems because of the nonlinear interaction between their wakes. The study identifies the main flow mechanisms responsible for these interference effects and provides quantitative information relevant to the aerodynamic analysis of dual-propulsion gyrodyne UAVs.