Rudy - Rudderless Yawing
The project RUDY is supposed to show the potential yaw moment generation of a wing-internal-flow system to counteract the adverse yaw of high-performance gliders. In contrast to existing approaches (e.g. application of spoilers), the yaw moment of the system increases when the drag (in terms of friction) of the system is minimized. When spoilers are applied, the yaw moment increases with the drag and will be small when drag is minimized. Following this argument, the system can be interpreted as non-drag based in terms of maximization of the moment which means minimization of the drag. These losses are theoretically predicted and validated with already measured results. The flow system is driven by the stagnation pressure only. To validate the moment-prediction theory, a tube system was tested in an in-house free-stream wind tunnel. The predicted values and the results achieved by the measurements agree well with each other. Moreover, it was shown that for actual geometrical parameters of a sailplane, the yaw moment produced by the internal-flow system and the adverse yaw have similar magnitudes. The adverse yaw was estimated, assuming the yaw is mainly based on the induced drag of the ailerons, using a lifting-line Multhopp method. Further details can be taken from the first patent publication .
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For further validation a free flight technology demonstrator (Rudy 4000) is developed within this project. It will be shown that the adverse yaw can be fully compensated even if the rudder is fully eliminated from the vertical tail plane. The demonstrator is a motorized scale glider with a span of approx. 4m.