The de Havilland DH.54 Highclere was a single-engined 15-passenger biplane airliner designed to replace the

DH.34 The de Havilland DH.34 was a single engined British biplane airliner built by the de Havilland Aircraft Company in the 1920s. 12 were built, with the DH.34 serving with Imperial Airways and its predecessors for several years. Design and develo ...

. Its development ended when

Imperial Airways Imperial Airways was the early British commercial long-range airline, operating from 1924 to 1939 and principally serving the British Empire routes to South Africa, India, Australia and the Far East, including Malaya and Hong Kong. Passengers ...

decided to use only multi-engined types.

Development

The DH.54 Highclere was designed to Air Ministry specification 40/22 for a larger version of the very successful

and the two aircraft had much in common, both in construction and general layout. Compared with the DH.34, the Highclere's passenger complement increased from nine to twelve, its all-up weight by 56% and its wing area by 70%. They were both single-engined two-bay biplanes with fabric-covered wooden wings and with wooden-framed fuselages covered with thin plywood. Size apart, the wings of the Highclere differed in having no stagger, no upper wing dihedral and in having a larger inter-wing gap, the upper wing now attached to the fuselage by cabane struts rather than directly to the upper fuselage. In response to criticism of the DH.34's high landing speed, full-span flaps were fitted. To reduce the hazards of ditching, the undercarriage could be jettisoned and the fuselage was made watertight. Passengers sat in four rows of seats, singles on the left and doubles on the right. A rearrangement of luggage space allowed room for toilets. The Highclere had balanced elevators. The weight increase required an increase in power, so the Highclere used a 650 hp (485 kW)

Rolls-Royce Condor The Rolls-Royce Condor aircraft piston engine was a larger version of the Rolls-Royce Eagle developing up to 675 horsepower (500 kW). The engine first ran in 1918 and a total of 327 engines were recorded as being built. Variants ''Note:'' ...

IIIA water-cooled inline engine which lengthened the nose and drove a four-bladed propeller of 14 ft (4.27 m) diameter.

Operational history

The Highclere was first flown by H.S. Broad on 18 June 1925 and was soon carrying non-paying passengers and winning races. Owned by the Air Ministry throughout its life, it went to RAF Martlesham Heath for successful airworthiness tests early in 1926, with the Certificate of Airworthiness awarded on 23 April 1926. By then, though

had decided no longer to transport passengers in single-engined types for safety reasons and the sole Highclere was transferred to

RAE Farnborough The Royal Aircraft Establishment (RAE) was a British research establishment, known by several different names during its history, that eventually came under the aegis of the UK Ministry of Defence (MoD), before finally losing its identity in me ...

on 7 March 1926 for experimental work. On 7 November 1926 it was loaned to Imperial Airways at Croydon Airport as a freighter and some thought was given to modifications to make the Highclere better fitted to this role, but it was destroyed when a hangar collapsed in heavy snow at Croydon on 1 February 1927.

Unbuilt variants

;DH.55 :Unbuilt design for 12-seat transport powered by three 120 hp (90 kW) Airdisco engines. ;DH.57 :Unbuilt derivative of DH.55 with three 230 hp (172 kW)

Siddeley Puma The Siddeley Puma was a British aero engine developed towards the end of World War I and produced by Siddeley-Deasy. The first engines left the production lines of Siddeley-Deasy in Coventry in August 1917, production continued until December 1 ...

engines.

Specifications

References

* * * {{de Havilland aircraft 1920s British airliners Highclere