Assessment of Wake-Tail Interference E ects on the Dynamics of Flexible Aircraft

This work investigates the e ect of aerodynamic interference in the coupled nonlinear aeroelasticity and ight mechanics of exible lightweight aircraft at low speeds. For that purpose, a geometrically-exact composite beam formulation is used to model the vehicle exible-body dynamics, by means of an intuitive and easily linearizable representation based on the displacement and Cartesian rotation vectors. The aerodynamics are modeled using the unsteady vortex-lattice method, which captures the instantaneous shape of the lifting surfaces and the free inviscid wake, including large deformations and interference e ects. This results in a framework for Simulation of High Aspect Ratio Planes that provides a mediumdelity representation of exibleaircraft dynamics with a modest computational cost. Previous independent studies on the structural-dynamics and aerodynamics modules are complemented here with the integrated simulation methodology, including vehicle trim, and linear and nonlinear time-domain solutions. A numerical investigation is next presented on a simple wingfuselage-tail con guration, assessing the interference e ects between wing-wake and horizontal tail, and the downwash due to the proximity of the wake is shown to play a signi cant role in the longitudinal dynamics of the vehicle. Finally, a brief discussion of direct wake-tail encounters is included to show the limitations of the approach.