engines. The B9 was intended to research the effects of high-g flight with the pilot lying in a prone position, being assigned the RLM designation 8-341. Akaflieg Berlin B10 Conceived in 1944, this two-seated twin-engined amphibian didn't pass the design stage. Akaflieg Berlin B11 Designed in 1963, the B11 was a single-seat tail less performance glider with negative wing-sweep. Construction of the prototype was not completed due to faulty design. Akaflieg Berlin B12 The B 12 is a two-seated epoxy-glass-resin performance glider with the seats in tandem. The main aim of the project was the optimisation of the aerodynamics of the fuselage at high speeds. The B12 has flaps and a retractable landing-gear and is still used by the group for performance flights and contests. The maiden flight was in 1977 at Ehlershausen near Hannover and the measured glide-ratio (Idaflieg-summer-meeting 1978) is 40.5. Akaflieg Berlin B13 The B13 is a two-seater epoxy-carbon-resin electric motor glider with the seats positioned side-by-side. The wing span is 23.2 m and the measured glide-ratio (Idaflieg-summer-meeting 1992) is 46.5. The wing profile is a modified flap-HQ-41-profile. Developed in the eighties, the B13 had its successful maiden flight in 1991 at Strausberg near Berlin. After the integration of the 33hp (24.5kW)Rotax engine, an innovative brushless linear induction motor was substituted, powered by energy from renewable sources using fuel cells and solar technology. Glider launch winch Because of the high take-off weight of the B13, the group decided in 1984 to design and construct a new more powerful winch to launch their gliders. Daimler-Benz donated a 320 HP 10-cylinder diesel engine including an axle and cable drums. In addition to achieving a higher performance, the project's aim was to make winch launching safer for modern gliders which have higher minimum speeds during a winch launch, especially on days when there is no wind or even a light tail-wind. By using big azimuth rollers and inclined inlet guides, the winch is designed to minimize the bending of the cable under load. The groups also designed automatic process controls for the pneumatically driven gearbox actuators;mounted on an all-wheel drive Tatra 148 chassis, the winch was finished in 1994 and has operated with Dyneema-plastics cables since 2004. References Bibliography External links Official website Videos B-12 B-13 Pictures Uwegranzow Videocommunity Vimeo idaflieg Aviation in Germany Aviation in Berlin Aircraft manufacturers of Germany Sailplanes, German German experimental aircraft