Development of the fs33 began in 1990 in response to the redefinition of the
FAI two-seater Competition Class in 1989. Additionally, the aircraft should be of high performance, while also possessing pleasant handling characteristics and being viable for regular usage. The design itself was to be based on experiences gained from older prototypes and production aircraft. The project was also supposed to be completed quickly. This led among other things to the use of pre-existing molds to reduce development and construction time. A further focus of the project was safety. To achieve the above-mentioned goals, the fuselage molds of the
Akaflieg Stuttgart fs31 were reused. Calculations were done based on the fs31's fuselage to determine the optimal geometry and mass for the vertical fin and tailplane, which led to the use of the fin of a
Nimbus-3D and tailplane of a
Nimbus-4D, though slightly modified to fit the fuselage. Furthermore, most of the control rods in the cockpit, the wheel brakes, and the rear lift pin tube were taken over from the
Schleicher ASH 25. To create the wings, the wing molds of the
Akaflieg Stuttgart fs32 were taken and extended inwards by 2,5 meters. Unlike in the fs32, the fs33 doesn't possess
slotted flaps due to their complexity, instead using regular
flaperons. Due to the lower than expected wing area gain, lightweight construction became an important factor to keep the design's
wing loading within acceptable levels. The fs33 is a two-seater glider with a
mid-mounted triple-trapezoidal wing. It has a wingspan of 20 meters and its wings are each equipped with three flaperons along the entire span and optional
winglets. Operation of the flaperons is controlled by a mixer located at the wing root and the wings' control connections with the fuselage are automatic. The aircraft is almost entirely made out of
carbon fiber composites, with the cockpit region being instead made out of a carbon-
kevlar hybrid. Carbon fiber
rovings were used to build the wing spars, while the skin was made of
carbon fiber scrims (
de) as a weight saving measure. Both pilots sit in tandem in a
cockpit placed forward of the wing, fitted with dual controls, under a long, single-piece
canopy. The fuselage is split horizontally, as with the fs31, instead of vertically to improve pilot safety during a crash landing by eliminating a seam on the underside of the cockpit. As an additional safety feature, the wings were designed to break off in the event of a crash landing. Originally the fs33 had an undercarriage constructed from carbon fiber composites with steel fittings to reduce weight, though this was later replaced with a steel one following the aircraft's crash. New winglets were built for the fs33 in 2016. ==Operational history==