The forgotten flap – The Gurney flap

The Gurney flap (or wickerbill) is a small tab projecting from the trailing edge of a wing. Typically it is set at a right angle to the pressure-side surface of the airfoil[1] and projects 1% to 2% of the wing chord.[2] This trailing edge device can improve the performance of a simple airfoil to nearly the same level as a complex high-performance design.

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