Slingsby Sky

The Slingsby Type 34 Sky is a high performance single seat competition sailplane built in the United Kingdom. It was successful in major events, particularly in the World Gliding Championships of 1952.

Design and development

The single seat Slingsby Sky resulted from Slingsby's experience at the 1948 International Gliding Contests, where they flew their 15 m span Gull IV. This convinced them that to be competitive against aircraft like the German Weihe, the Gull's successor would have to have a span of 18 m or more. Consequently, the Sky was aerodynamically identical to the Gull IV apart from span (and hence aspect ratio) and length, though it differed in construction. It dominated the 1952 Contests and was well placed in both 1954 and 1956.

The Sky is a wooden aircraft, using the traditional spruce for stressed members and birch ply elsewhere. Its wing has a constant chord inner section over the first 30% of span, then tapers on both edges to a rounded tip. The 20% increase in span over the Gull IV was achieved with two extra rib bays in the inner part and a 2 in (51 mm) increase in rib separation outboard. The Sky was designed to meet semi-aerobatic requirements which together with an aspect ratio of 18.7, which was high for the time, required the single box spars, 6 in (152 mm) wide at their greatest, to be massive. Their weight is 25% of that of the whole aircraft. The wing ahead of this spar, positioned at 30% chord, forms a plywood covered torsion box. Behind it, the wing is fabric covered. Ailerons, divided to allow for wing flexure, fill the tapered trailing edges. Air brakes are mounted on the spars as aerodynamically balanced pairs above and below wing; the lower panel open into the airstream and lever the upper ones against it. There were no flaps.