The yaw-control device of a low aspect-ratio flying wing with diamond shaped wing planform is investigated. Extensive
low-speed wind tunnel experiments have been carried out to obtain the aerodynamic forces and moments of the configuration
for six different flap deflection angles at varying angle of attack and angle of sideslip. Complementary Reynolds-Averaged
Navier-Stokes simulations are performed for selected configurations. The experimental data is used to examine the validity
of the numerical results. The analysis focus on the aerodynamic coefficients and derivatives. The induced yawing moment,
yaw-control efficiency, coupling effects with the rolling moment and effects on the longitudinal aerodynamic coefficients are
discussed. The results show a non-linear flap characteristic for a wide range of angles of attack. The flap efficiency is low for
small flap deflections , but significantly increases for larger deflections. The efficiency is considerably reduced at high angles
of attack due to flow separation in the wing-tip area. Furthermore, a minor influence of the angle of sidesilp on the flap efficiency
is observed. Non-linear coupling effects with the rolling moment become obvious for moderate to large flap deflections.
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