Outboard split flap aerodynamics of a flying wing configuration

The yaw-control device of a low-aspect-ratio flying-wing configuration is investigated. The novel layout of the so-called outboard split flap with its hinge-line along the swept leading edge is designed to achieve beneficial yaw-control characteristics. Force and moment measurements as well as stereo particle image velocimetry measurements allow for the analysis of the aerodynamics of the control device. Additionally, Unsteady Reynolds-Averaged Navier-Stokes simulations are performed and compared to the experimental data. Different outboard split flap deflections are investigated at zero degree angle of attack and sideslip. The created force and moment increments of the deflected flap show, that the yawing moment is created by a force vector composed of a drag and side force contribution of similar magnitude. The effective lever arm of the outboard flap increases with the flap deflection angle and reaches a value of the magnitude of the wing half span. The wake flow shows significant axial and lateral velocities in consequence of the deflected flap, which can be associated with the forces originating at the flap. The numerical results represent the characteristics of the outboard flap well with minor deviations in the absolute values.