Multi-Mode Wind Tunnel Testing of Tiltrotor UAV Propellers with Integration for Propulsion and Flight Dynamics Modeling

Accurate modeling of tiltrotor unmanned aerial vehicles (TRUAVs) is essential for their efficient design, control, and operation. Among all subsystems, the propulsion system, particularly the tilting rotors, forms the core distinguishing feature that differentiates TRUAVs from conventional fixed-wing platforms and represents the most critical component requiring precise modeling. The complexity of this task arises from the varying aerodynamic conditions encountered throughout the three flight regimes: vertical, transition, and forward flights. Addressing this critical aspect, this study aims to develop, verify, and validate a comprehensive and systematic methodology for modeling TRUAV propulsion systems across all flight modes. Unlike prior studies that primarily focus on isolated component characterization, this work establishes a unified framework that links axial/non-axial aerodynamic measurements and identified actuators dynamics directly to full-vehicle flight simulation. A case study TRUAV, equipped with two forward-tiltable rotors and a fixed tail rotor, is used to demonstrate the procedure. The study begins with wind tunnel testing of the tiltable rotors under axial and non-axial flow conditions, alongside axial flow testing of the tail rotor. Subsequently, dynamic models of the forward electric motors and their tilt servo actuators, as well as the tail motor, are developed via system identification techniques based on measured data. The propulsion system simulation model is then constructed to predict thrust, torque, and off-axis forces and moments in the TRUAV body-fixed reference frame for given control inputs, tilt angle, flight velocity, and altitude. The developed propulsion model is verified and validated by integrating it into a six-degree-of-freedom (6- DoF) flight dynamics simulation. Verification is done by comparing the model’s simulation results against analytical results, while validation is achieved by comparing them with flight test data The good agreement between simulation, analytical predictions, and flight test data verifies the reliability of the proposed modeling methodology. This framework integrates experimental aerodynamic characterization, propulsion dynamics, and full-vehicle simulation, yielding a comprehensive simulation tool for TRUAV design, analysis, and control across multiple flight phases, with system-level flight validation–independent of the component-level wind tunnel characterization–explicitly demonstrated in fixed-wing mode.