Akaflieg Stuttgart FS-31
|Role||Tandem two seat sailplane|
|First flight||30 December 1980|
The Akaflieg Stuttgart FS-31 is a tandem seat, dual control training glider designed and built in Germany in 1980. The aircraft was intended to have high performance, yet to be robust enough for student use. It was not intended for production and remains in service with the Akaflieg after some 30 years and 6,000 flying hours.
Design and development
The Akaflieg Stuttgart or Akademische Fliegergruppe Stuttgart (English: The Stuttgart Academic Flying Group) is one of some fourteen German student flying groups attached to and supported by their home Technical University. Several have designed and built aircraft, often technically advanced and leading the development of gliders in particular.
The students of the Stuttgart Akaflieg designed the FS-31 as a high performance, tandem seat training sailplane to replace their earlier aircraft, using the then new carbon Kevlar hybrid material to reduce the weight. Energy dissipation and a locally strong cockpit area were further design objectives. Benign stall characteristics and a strong, long-stroke, monowheel undercarriage also make it suitable for student pilots.
The FS-31 has mid-mounted, straight tapered wings with 4° of dihedral, fitted with spoilers. Its T-tail has a narrow chord, weakly tapered tailplane. Instructor and pupil sit in tandem in a cockpit placed forward of the wing, fitted with dual controls, under a long, single piece canopy. The fuselage, which narrows to a slender boom behind the wing trailing edge, is similar to that of the Akaflieg Stuttgart FS-29, though carbon/Kevlar replaces the earlier aircraft's GRP polymeric foam sandwich structure.
The sole FS-31 was still undergoing field trial when it won the Klippeneck gliding competition of July 1982. Since then it has served the Akaflieg in its intended role of trainer for about 30 years, logging over 6,000 flying hours.
Data from Jane's All the World's Aircraft 1981/2
- Crew: 2
- Length: 8.70 m (28 ft 7 in)
- Wingspan: 17.50 m (57 ft 5 in)
- Wing area: 17.76 m2 (191.2 sq ft) 
- Airfoil: Eppler E 603 modified
- Empty weight: 340 kg (750 lb)
- Max takeoff weight: 560 kg (1,235 lb)
- Simons, Martin (2005). Sailplanes 1965-2000 (2nd revised ed.). Königswinter: EQIP Werbung & Verlag GmbH. p. 41. ISBN 3-9808838-1-7.
- "FS31 data from AK Stuttgart". Archived from the original on 22 September 2012. Retrieved 22 February 2012.
- Taylor, John W. R. (1981). Jane's All the World's Aircraft 1981-1982. London: Jane's Information Group. p. 576. ISBN 0-7106-0705-9.
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