Freeplay and Preload Effects on the Aeroelastic Behavior of the XDIA Wind Tunnel Model: 2025 Test Results and Insights

The F-XDIA aeroelastic wind tunnel model was tested in 2025 in the large Politecnico di Milano wind tunnel to study its behavior in the presence of aileron freeplay, rigid body freedom to pitch and roll, and at different angles of attack, with the different angles of attack leading to different levels of preload on the wing and ailerons. The paper describes the tests and presents key results. Of particular interest is the effect of preload on the aeroelastic behavior in the presence of freeplay. The results of the tests will serve to study the capability of state of the art nonlinear aeroelastic analysis and simulation techniques to accurately capture the physical behavior that was observed and studied in the wind tunnel.