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Self-launching motor glider whose engine is retracted into the fuselage when gliding.

The AK 1 was a precursor of the now commonplace motor gliders with foldable propellers. The other design type is the fixed-engine motor glider, such as the Valentin Taifun, which is also shown in the exhibition). The retractable-engine type has the advantage that performance and gliding characteristics are not significantly worse than those of conventional gliders despite the engine.

Motor gliders do not need a winch or tow plane and the various assistants to get airborne. The engine is used for take-off, but also as a “booster” when thermals are too weak to support soaring. This reduces the risk of having to land away from the home base.

The wings and tail of the AK 1 have a metal structure, and the fuselage consists of a steel-tube lattice work with a fibreglass-reinforced plastic shell. The engine and propeller are a single unit, and are extended together. The one-of-a-kind AK 1 made its maiden flight on January 9, 1971 and flew for the last time on October 18, 2008.

Technical specifications:

  • Manufacturer: Akademische Fliegergruppe Karlsruhe, Karlsruhe, 1971Wingspan:15.0 m
  • Wing aspect ratio: 15.65
  • Surface loading: 26.5 kg /100 km
  • Empty weight: 300 kg
  • Min. sink rate: 0.68 m/s at 70 km/h
  • Best glide ratio: 30 at 80 km/h
  • Climb performance: 1.6 m/s
  • Speed: 100 km/h
  • Power plant: Four-cylinder two stroke Hirth F 10 A1a engine
  • Power rating: 19 kW (26 HP) at 5000 r.p.m.