Akaflieg Darmstadt D-36
| D-36 Circe | |
|---|---|
| Role | High performance sailplane |
| National origin | Germany |
| Manufacturer | Akaflieg Darmstadt |
| Designer | Wolfe Lemke, Gerhard Weibel and Heiko Friess |
| First flight | 28 March 1964 |
| Number built | 2 |
| Developed into | Schleicher ASW 12 |
The Akaflieg Darmstadt D-36 Circe is a single seat, high performance sailplane designed and built in Germany in the mid-1960s, one of the early "glass ships". It was the winner at the German National Championships in 1964 and came second in the World Championships the following year.
The Akademische Fliegergruppe of the Technical University of Darmstadt (Akaflieg Darmstadt) was first formed in 1921. It was, and is, a group of aeronautical students who design and construct aircraft as part of their studies and with the help and encouragement of their University. Design work on the Circe began in 1962-3 by a team of students, Wolf Lemke (responsible for the wing), Gerhard Waibel (fuselage and tail) and Heiko Friess (airbrakes). They were later joined by the younger Klaus Holighaus. Professor Franz Wortmann designed a new airfoil for the Circe. Construction began in 1963 and the aircraft flew for the first time, piloted by Wolfe Lemke, on 28 March 1964 at Gelnhausen.
The Circe is built from composite materials, with flying surfaces and fuselage shells made from glass-balsa-glass sandwiches. The wings have a single spar with flanges of aligned glass fibre (uni-directional rovings) and a glass-balsa sandwich web. The fuselage has GRP-balsa stiffening cross-members. The wing is tapered in two sections, with more taper on the outer 40% of the span. Such double taper plans can provide lift/drag ratios close to that of the ideal elliptical wing, and have benign stall characteristics.Ailerons occupy all the trailing edge of the outer panels, with flaps across the inner panels. Four sets of Schempp-Hirth airbrakes, two per wing, are located just behind the spar, roughly centred on the inner panels. Each set extends its surfaces, mounted like parallel rulers, above and below the wing. They were difficult to design because of the considerable flexure of the wing, the latter leading to the Circe's nickname of Gummiflügel (English: Rubberwing) at a time of stiffer structures.
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