UIUC Airfoil Coordinates Database (Reference)

Last update 12/15/95

S7012 (8.75%) for R/C Soaring

During the Princeton airfoil tests, several attempts were made to design an F3B airfoil (hot thermal/duration airfoil) that out-performed the RG15, which was then and is still among the best-arguably the best. During those design process at Princeton, the objective was to develop an airfoil with lower drag everywhere. In hindsight that objective is not physically possible. To improve on the RG-15 performance requires making some compromises. The question is then where should the emphasis on improving performance be placed and in turn where is performance less critical.

Ask any F3B pilot and he will tell you that he wants better speed, distance and thermal performance. There's nothing he can give up! But actually, between the distance speed and thermal speed there is a wide lift range (speed range) that is less critical and rarely used. This little used region of performance can be traded in exchange for better performance elsewhere. According to predictions and recent wind tunnel tests (to be published in an upcoming issue of SoarTech), the S7012 gives up performance in this range (between thermal and distance speeds) for improved performance where it is most needed. Also, the speed range for thermalling has been reduced. Consequently, maintaining nearly constant speed during thermal soaring key. These tradeoffs lead to the following benefits. In exchange for the narrower thermal speed range, the lower thermal drag should increase duration times by 4% - a difference that can be detected by a pilot. Relative to the RG15, the S7012 has lower drag in the speed lift range of the polar. Thus, speed should be improved. Also, for distance, the new airfoil will match the performance of the RG15 in weak course conditions, and when conditions are strong the new airfoil might surpass the RG15 by 1-2 laps.