Slingsby Sky
| Sky | |
|---|---|
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| Role | Single seat competition sailplane |
| National origin | United Kingdom |
| Manufacturer | Slingsby Sailplanes Ltd., Kirkbymoorside, Yorkshire |
| Designer | F.N. Slingsby |
| First flight | September 1950 |
| Number built | 16 |
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.
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.
The cockpit of the Sky is of standard Slingsby design and built on the same jigs as those used on the Gull IV and Kite II, with a single piece perspex canopy hinged on the starboard side. It is placed immediately in front of the leading edge of the wing and the fuselage neck on which the wing is mounted. Behind the cockpit the fuselage is a semi-monocoque structure, with a stress bearing 1/16 in (1.6 mm) plywood skin formed over light frames positioned by three longitudinal stringers. There is additional strengthening around the wheel bay, where the single wheel has its axle held clear of the fuselage by small triangular pieces. An ash skid is mounted away from the fuselage, running forward to the nose. The wheel brake is applied at the greatest air brake extension. As a weight saving alternative to the mono-wheel, a jettisonable two wheel dolly can be used for take-off. Another ash skid at the rear forms a bumper. The tail unit was initially identical to that of the Gull IV: the tailplane has a ply covered leading edge and fabric behind, mounted forward of the ply covered fin so that the rudder hinge is in line with the trailing edge of the single piece, fabric covered elevator. The latter carries trim tabs.
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