Mid-Fidelity Aeroelastic Framework for Main Rotor Load Prediction in Forward Flight of Medium Utility Helicopters

Rotorcraft in forward flight exhibit complex aeroelastic interactions owing to the coupling of unsteady aerodynamics with structural flexibility. This study presents a mid-to-high-fidelity aeroelastic framework for a medium-utility helicopter, integrating a nonlinear vortex-lattice method/vortex particle method (NVLM/VPM) aerodynamic solver with geometrically exact beam theory (GEBT) for rotor blade dynamics. The framework captures full geometric nonlinearity and inertial coupling, with a loosely coupled δ-airload scheme linking aerodynamics and the structural response at each trim state. Simulations at 40, 100, and 140 knots demonstrate good agreement with the CAMRAD II results, validating the accuracy of the wake-resolved aerodynamics and nonlinear blade dynamics. The results show that the proposed GEBT–NVLM framework offers a reliable research tool for accurate aeroelastic load prediction and early-phase evaluation of active control strategies.