Low-Order Longitudinal Simulation of Tilt-Rotor VTOL Transition Flight with Airfoil-Based Aerodynamics and Dynamic Stall

Abstract

Vertical Take-Off and Landing (VTOL) aircraft encounter unique aerodynamic challenges during the transition between hover and forward flight, and accurate modeling of this behavior is therefore essential. Post-stall and unsteady aerodynamic effects can significantly influence aircraft performance and stability during this transition phase. This study develops and evaluates a low-order longitudinal aerodynamic simulation of a tilt-rotor-type VTOL configuration, in which a single thrust-vectoring force represents the rotor propulsion system while the wing remains fixed relative to the fuselage, and which reproduces the qualitative features of transition flight while maintaining computational efficiency. The model combines Newton-Euler rigid-body dynamics with airfoil-based coefficient modeling derived from NACA 0012 polar data. Helmbold lift-curve-slope corrections incorporate finite-wing effects, while poststall behavior is represented through a Kirchhoff trailing-edge separation model paired with a Beddoes- Leishman-type dynamic-stall formulation. The thrust-vectoring propulsion model is integrated with the longitudinal equations of motion to simulate lift redistribution between rotor thrust and aerodynamic lift during transition. Verification confirms a 20% reduction in the lift-curve slope (5.04 rad−1) due to threedimensional effects and accurate reproduction of unsteady hysteresis loops. Component-level validation against published NACA 0012 polar data further supports the static aerodynamic model. Parametric studies demonstrate that short transition durations (td = 5 s) provoke deep dynamic stall excursions, driving the peak angle of attack to 26° with near-complete flow separation. Longer transitions reduce these transients, revealing an operational sweet spot between 10 s and 15 s where the flow remains largely attached. This framework offers an efficient, physically transparent tool for preliminary design and parametric studies of tilt-rotor VTOL transition flight.