Akaflieg Stuttgart fs 29
The first and, so far, the only sailplane that allows the pilot to vary the wing span in flight.
This allows it to be adapted to the different requirements in flight. The same objective was pursued with the Mü 27 of Akaflieg Munich, but with a wing flap.
Performance-type gliders must meet different requirements during flights: In thermic flight, the glider is expected to fly slowly and in narrow circles to gain altitude but then it must convert the gained altitude into the longest possible distance in a fast gliding flight. For low-speed flights, a low wing load (the ratio of the all-up weight to the wing area) is optimal, for high-speed flights a high wing load is best. This can be achieved by means of a variable wing span. For this purpose, the outer wings are moved across the inner wings by means of a manually operated mechanism. Due to the high expenditure involved in the design and construction, and because of the large requirements imposed upon the pilot regarding the optimal choice of the wing span, the use of this design was limited to this airplane.
The airplane, which remained unique as a research aircraft, was flown by members of the Akaflieg Stuttgart from 1975 to 2003.
- Manufacturer: Akademische Fliegergruppe Stuttgart, Stuttgart 1975
- Wingspan: 13.3 m to 19.0 m
- Wing aspect ratio: 20.7 to 28.5
- Wing load: 52.6 to 36.5 kg/m²
- Weight, empty: 365 kg
- Minimum sink rate: 0.56 m/s at 81 km/h
- Best glide ratio: 44 at 98 km/h