Flight Dynamics of Flexible Aircraft with Aeroelastic and Inertial Force Interactions

This paper presents an integrated flight dynamic modeling me thod for flexible aircraft that captures coupled physics effects due to inertial forces, aeroelasticit y, and propulsive forces that are normally present in flight. The present approach formulates the coupled flight dy namics using a structural dynamic modeling method that describes the elasticity of a flexible, twisted, swept wing using an equivalent beam-rod model. The structural dynamic model allows for three types of wing elastic motion: flapwise bending, chordwise bending, and torsion. Inertial force coupling with the wing elastici ty is formulated to account for aircraft acceleration. The structural deflections create an effective aeroelastic angle of attack that affects the rigid-body motion of flexible aircraft. The aeroelastic effect contributes to ae rodynamic damping forces that can influence aerodynamic stability. For wing-mounted engines, wing flexibilit y can cause the propulsive forces and moments to couple with the wing elastic motion. The integrated flight dy namics for a flexible aircraft are formulated by including generalized coordinate variables associated with the aeroelastic-propulsive forces and moments in the standard state-space form for six degree-of-freedom fli ght dynamics. A computational structural model for a generic transport aircraft has been created. The eigenvalue analysis is performed to compute aeroelastic frequencies and aerodynamic damping. The results will be used to construct an integrated flight dynamic model of a flexible generic transport aircraft.