What does 4F stand for in 4F Sailplanes? Flex-Fuse Free-Flight  4F Sailplanes by AeroRacers Inc. feature: Flex-Fuse automatic steering Ballast Shift for precise center-of-gravity adjustment Fun Saver crash-protection system Rapid Wing Joining system Flex-Fuse explained: Our patent-pending Flex-Fuse system allows 4F sailplanes to ascend straight on the high-start launcher until reaching apogee. Once the glider releases from the […]