Mr W. L. Manuel, who designed the Willow Wren and other gliders during the 1930s, continued working during retirement by designing and building the Hawk single-seater, intended for soaring in weak thermals.
The Hawk has a wing of rather low aspect ratio (11.88) and a fuselage that, although well steamlined, is not as slim as some contemporary types. The cantilever shoulder wing is a three-piece wooden structure with a centre section and two outer panels; the single spar is of spruce with a plywood leading edge torsion box and fabric covering aft of the spar, and there are air brakes in the wing upper surfaces. The semi-monocoque fuselage is of spruce covered by plywood, with a non-retractable monowheel for landing. The T-tail is of wooden construction, with a trim tab in the starboard elevator and a small dorsal fin. Instead of the conventional one-piece cockpit canopy, a three-piece one is fitted in which the front and rear sections are fixed one-piece single-curvature transparencies and the hinged middle section is a framed double curve segment.
The prototype was built at Fairoaks in Surrey during 1968-70 and made its first flight at the College of Aeronautics airfield at Cranfield on 25 November 1972. Initial flight tests revealed the need for some modifications, including revised aileron controls, removing the air brakes from the wing under surfaces and increasing the rudder area; further flight testing followed these changes.
Span: 42 ft 0 in
Length: 20 ft 6 in
Wing area: 149 sqft
Aspect ratio: 11.88
Empty weight: 406 lb
Max weight: 639 lb
Max speed: 90 mph
Min sinking speed: 2.53 ft/sec at 38 mph
Best glide ratio: 25:1 at 41.7 mph