Gurney flaps are now available for all of APR's GTC-series (200/300/500) wings. These are super lightweight, made in carbon fiber using the pre-pregnated "dry" carbon process, and conform perfectly to the contours of the GTC-series 3D airfoils. They are easily attached using the included double-sided tape.
The Gurney flap (a.k.a. wickerbill) is an aerodynamic device that was originally pioneered and developed in the 1970s by a racing driver named Dan Gurney. Unbeknownst to his competition, this device was used to increase downforce while minimizing increase in drag. He found that not only did this device increase the lift/drag (L/D) ratios, it also increased the stalling angles (so he could operate the airfoils at greater pitch angles). It took a few years for everyone else to catch on to its purpose, and now, the Gurney flap (or similar device) can be seen in race cars and even airplanes all over the world.