Apart from their engines, the de Havilland DH.42 Dormouse and DH.42A Dingo I were very similar aircraft. The Dormouse was built to
Air Ministry specification 22/22 as a two-seat reconnaissance fighter and the Dingo to
Specification 8/24 for army cooperation. They were two-bay biplanes with unswept wings of constant chord, though the lower wing was slightly smaller in span and only about 73% of the chord when compared to the upper one. The two trailing edges were in line and the trailing struts vertical, but the forward struts were forward-raked. Both wings carried unbalanced ailerons. The vertical tail had the characteristic DH shape, with a balanced rudder; the elevators were unbalanced. The structure throughout was wood, with fabric covering on the wings and empennage, but with de Havilland's usual thin plywood cover on the fuselage. There was a single axle undercarriage, with the main legs attached to the lower wing root and with bracing to the forward fuselage. The pilot's cockpit was under the upper wing centre section and the gunner sat close behind at the trailing edge. In the Dormouse, the pilot had an oval cutout in the wing for upward vision and the gunner a V-shaped notch in the trailing edge to ease his field of fire. In the Dingo, the pilot's cutout was made smaller and circular, whilst the gunner's notch was increased to fuselage width and deepened to the rear wing spar, giving it a straight edge. It used the slightly more powerful (436 hp, 325 kW) Jupiter IV, carried more fuel and had the same top speed as its wooden equivalent. ==Operational history==