Structural and aeroelastic analyses of a composite tactical unmanned air vehicle

Özöztürk, Sedat
In this thesis, computational aerodynamics, structural and aeroelastic analyses of the composite tactical unmanned air vehicle which is designed and manufactured in the Department of Aerospace Engineering are performed. Verification of the structural integrity of the air vehicle is shown at the minimum maneuvering and the dive speeds at the static limit loads which are calculated by the computational aerodynamics analysis of the full aircraft model. In the current work, aerodynamic loads are re-calculated for more accurately determined dive speed angle of attack in an effort to match the overall vertical pressure load more closely to the half of the aircraft weight at the positive load factor. Finite element models of the fuselage, wing and the vertical-horizontal tail plane are prepared including the filament wound boom connecting the wing and the tail plane. Structural analyses of the composite wing, vertical and horizontal tail plane are performed under the limit aerodynamic loads calculated at the corner points of the V-N diagram using the structural finite element model of the wing-tail plane combination only. Global finite element analysis of the wing-tail plane combination showed that composite and isotropic materials of the wing-tail plane combination have positive margins of safety. Woven carbon and E-glass fabric that was procured to be used for the serial production version of the airplane are characterized for the tensile properties by the tests. Comprehensive aeroelastic stability analyses of the airplane are conducted by adding one sub-structure at a time to the aeroelastic model. Specifically, aeroelastic models which are used are the wing only, wing-tail plane combination, complete air vehicle with and without wing control surfaces. With such a study it is intended to address the effect each sub-structure adds to the aeroelastic model on the critical aeroelastic stability modes and speeds, and to see how sensitive the aeroelastic stability modes and speeds are to model fidelity. Detailed structural and aeroelastic analyses showed that the airplane has sufficient structural integrity under the action of static limit loads, and no aeroelastic instability is expected to occur within the flight envelope of the airplane.