De Havilland DH.52

de Havilland

Industry	Aerospace
Headquarters	United Kingdom

The de Havilland DH.52 was a high-wing, single-seat glider designed to participate in a 1922 prize contest. Only two units were constructed; however, the wings lacked sufficient torsional rigidity, which caused difficulties with control and led to the rapid discontinuation of the model.

Development

The DH.52 was the sole glider created by de Havilland, intended for entry in the Daily Mail Gliding Competition at Itford, Sussex in 1922, which offered a £1000 reward. This aircraft featured a high-mounted monoplane wing with an aspect ratio of 11.4. The wing structure was supported by wire bracing, with pairs of wires extending from the keel to both the front and rear spars at approximately one-third and three-quarters of the wing span. Additional pairs of wires attached to a central king post maintained wing load support and kept the bracing under tension. The kingpost consisted of two members originating from each wing spar at the centerline, converging roughly 2 feet 9 inches (0.84 m) above the wing surface. This triangular framework appeared to be covered with cambric. The glider was equipped with unbalanced ailerons that allowed unusually large angular movement to preserve control effectiveness at low airspeeds.

The fuselage had a square cross-section, constructed from spruce longerons reinforced with cross bracing and sheathed in 0.04 inches (1.0 mm) plywood. Toward the nose, these longerons tapered inward, giving the aircraft a somewhat boat-like appearance. The pilot's cockpit was positioned just forward and beneath the wing. A cambric fairing surrounded the cockpit area and extended aft beyond the wing to the tail, formed by stretching fabric over a wire running from the wing mount to the rear fuselage. The fin and generously sized rudder exhibited a slightly pointed variation of de Havilland’s characteristic shape; similarly, the elevator area was relatively large compared to the fixed tailplane.

Two examples of the DH.52 were produced. The first (competition number 4) initially featured a single cross-axle undercarriage supported by struts for its maiden flight on 5 October 1922; this was later replaced by two smaller wheels mounted close to the fuselage sides on an axle attached to the lower longerons. The second aircraft (number 33) was equipped with this latter undercarriage configuration from its inception.

Both gliders participated in the competition on 16 October using rubber rope launches. Each managed flights lasting about two and a half minutes but sustained damage upon landing. Both exhibited issues with lateral control as their wings twisted under aileron forces, negating control inputs. After repairs, number 33 flew again three days later, now employing wing warping to address control difficulties; however, excessive wing twisting following tow release caused failure in the center section, resulting in loss of the glider. Although the pilot escaped serious injury, it became evident that wing torsional stiffness was inadequate and could not be remedied within the competition timeframe. Consequently, no further flights were attempted and both DH.52 units were dismantled.