Wing-Propeller Aeroelastic Stability Under Aerodynamic Interactions Using the Unsteady Vortex-Lattice Method

This paper investigates the impact of aerodynamic interactions on the dynamic aeroelastic stability of a wing-propeller configuration, with emphasis on whirl flutter. The wing structural dynamics are modeled using linear Euler-Bernoulli beam finite elements, while the propeller is represented using Reed's two-degree-of-freedom model. Baseline stability analyses neglecting aerodynamic interactions employ strip theory for the wing and the Houbolt-Reed formulation for the propeller. Analyses that account for aerodynamic interactions are then performed by coupling the wing and propeller structural models with the unsteady vortex-lattice method. Whirl flutter points are identified from transient simulations under both thrusting and windmilling conditions. Results show that three-dimensional aerodynamic effects increase the whirl flutter speed, whereas wing-propeller aerodynamic interactions play a slightly destabilizing role. Thrusting conditions produce a lower critical speed than the wind-milling case. The results demonstrate the viability of the unsteady vortex-lattice method as a unified aerodynamic framework for aeroelastic stability analysis of wing-propeller systems with mutual aerodynamic interactions. In addition, they reinforce findings from previous work that highlighted the destabilizing role of wing-propeller aerodynamic interactions.