Development of Tools and Methods for Characterizing the Impact of Control Surface Free-Play on Flutter

The aerodynamic performance of aircraft is significantly impacted by the aero-elastic dynamics of its control surfaces. In particular, the dynamics of flutter - an unstable self-excitation of structure due to undesirable coupling of structural flexibility and aerodynamics - has critical impact on the stability and performance of aircraft. The control surface flutter characteristics are affected by the unavoidable free-play which is inherent in the control surface due to manufacturing imperfections. There are no systematic methods to predict free-play effect on flutter. The proposed research will develop a comprehensive tool-suite which will: (a) provide state-of-the-art capability for stability and performance analysis of any generic control surface configuration, (b) allow modeling of control surface dynamics with varying degrees of fidelity using combination of analytical, computational, and experimental identification methods, (c) provide new analysis techniques to enable accurate prediction of stability/performance boundaries for existing platforms, and (d) provide optimal design capability for design of control surfaces for new platforms. The Phase 1 of the project will develope essential elements of the proposed tool-suite to prove the feasibility of the approach and demonstrate the capabilities by using 1950's WADC test data for all-movable un-swept horizontal tail.