Determining the Stability and Control Characteristics of High- Performance Maneuvering Aircraft Using High-Resolution CFD Simulation with and without Moving Control Surfaces

This paper discusses the development of a computational approach for accurately determining static and dynamic stability and control characteristics of USAF high-performance fighter aircraft. A graduated approach is used to incrementally add Computational Fluid Dynamics (CFD) simulation capability using DoD HPC resources. Static simulations, prescribed motion flight test maneuvers, and System Identification (SID) of CFD have been accomplished and show good predictive capabilities when tested against wind tunnel data and Lockheed Martin's performance data. The focus of this paper is the modeling and simulation of moving control surfaces in CFD and calculating aircraft/store increment data for use in flight test preparation and analysis. Flight test maneuvers were performed in CFD using both flight test data and maneuver response data from Lockheed Martin's 6-DOF and flying qualities simulation, ATLAS. Non-flyable, computational training maneuvers designed to capture both static and dynamic aerodynamics as well as aiding discovery of envelope-limiting, nonlinear aerodynamic phenomena are simulated as forced rotational and/or translational oscillations about one or more axes. Nonlinear, reduced-order aerodynamic models of USAF fighter aircraft with and without stores have been generated through SID of the aforementioned computational training maneuvers. A full-scale F-16C aircraft with movable control surfaces is modeled using unstructured viscous over-set grids and the Cobalt solver. Current work to employ external feedback control to manipulate movable control surfaces and boundary conditions in CFD is discussed. The necessity of DoD HPC resources to support the USAF T&E community in gathering critical data in a timely manner to rapidly deliver capability to the warfighter is reaffirmed.