De Havilland Dormouse

de Havilland DH.42 Dormouse and DH.42A/B Dingo

Company type	Aircraft series
Industry	Aerospace
Founded	1923
Headquarters	United Kingdom
Products	Military reconnaissance and army cooperation biplanes

The de Havilland DH.42 Dormouse along with its two derivatives, the de Havilland DH.42A Dingo I and II, were single-engine, two-seat biplanes created to fulfill fighter-reconnaissance and army cooperation missions. None of these models progressed to mass production.

Development

The DH.42 Dormouse and the DH.42A Dingo I shared many design elements, differing mainly in their powerplants. The Dormouse was developed in response to Air Ministry specification 22/22 targeting a two-seat reconnaissance fighter, while the Dingo was designed according to Specification 8/24 for army cooperation duties. Both aircraft were configured as two-bay biplanes featuring straight, constant-chord wings; however, the lower wing had a slightly reduced span and measured roughly 73% of the chord length relative to the upper wing. The trailing edges of both wings aligned horizontally with vertical trailing struts, whereas the forward struts were angled forward. Unbalanced ailerons were installed on both upper and lower wings. The vertical stabilizer bore the distinctive de Havilland profile with a balanced rudder, while the elevators remained unbalanced. The airframe was constructed primarily from wood, with fabric-covered wings and tail surfaces, complemented by de Havilland’s characteristic thin plywood fuselage covering. The undercarriage featured a single axle, with main landing gear legs mounted at the lower wing roots and braced forward to the fuselage. Pilot seating was positioned beneath the upper wing’s center section, with the observer/gunner located immediately aft near the trailing edge. On the Dormouse, an oval cutout in the upper wing improved the pilot’s upward visibility, and a V-shaped notch in the trailing edge enhanced the gunner’s firing arc. In contrast, the Dingo featured a smaller circular cutout for the pilot and a deeper, fuselage-width notch extending back to the rear wing spar for the gunner.

The Dormouse took to the air for its maiden flight at Stag Lane on 25 July 1923 equipped with a 360 hp (270 kW) Armstrong Siddeley Jaguar II radial engine. Its successor, the Dingo, first flew on 12 March 1924 powered by a 410 hp (305 kW) Bristol Jupiter III radial engine. Due to its nine-cylinder Jupiter engine having a larger diameter (53 in / 1.35 m) compared to the double-row fourteen-cylinder Jaguar (43 in / 1.06 m), the Dingo’s twin forward-firing guns were mounted externally atop the nose; in contrast, these guns were housed within internal tunnels on the Dormouse. Subsequently, the Dormouse was upgraded with a more powerful Jaguar IV engine delivering 420 hp (313 kW), along with modifications to its upper wing center section to match that of the Dingo. Both aircraft stored fuel in paired aerofoil-shaped tanks positioned above the inner interplane struts on top of the upper wing.

The last variant in this series was the DH.42B Dingo II, which conducted its first flight on 29 September 1926. Externally resembling its predecessors, this model differed by employing a steel frame instead of wood. It exhibited an 18% increase in empty weight compared to the Dingo I. Powered by a slightly more potent Jupiter IV engine producing 436 hp (325 kW), it also carried additional fuel but maintained an equivalent maximum speed to its wooden-framed counterpart.

Operational history

A total of only three units were produced. The Dormouse operated at the Royal Aircraft Establishment, Farnborough within the Wireless & Photographic Flight, conducting experimental radio tasks from March until December 1925, after which it was retired. The Dingo I was lost in a crash at RAF Martlesham Heath during testing in June 1924, and the Dingo II was delivered to Farnborough in November 1926.

Variants

DH.42 Dormouse

Powered by Armstrong Siddeley Jaguar III and Armstrong Siddeley Jaguar IV engines

DH.42A Dingo I

Equipped with Bristol Jupiter III engine; featured a modest span increase of 6 inches (152 mm)

DH.42B Dingo II

Utilized Bristol Jupiter IV engine; retained DH.42A dimensions but incorporated a steel frame and increased weight