The de Havilland DH.54 Highclere was a single-engined 15-passenger biplane airliner designed to replace the DH.34. Its development ended when Imperial Airways

Imperial Airways

Imperial Airways was the early British commercial long range air transport company, operating from 1924 to 1939 and serving parts of Europe but especially the Empire routes to South Africa, India and the Far East...

 decided only to use multi-engined types.

Development

The DH.54 Highclere was designed to Air Ministry specification 40/22 for a larger version of the very successful DH.34 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 9 to 12, 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 re-arrangement 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

Rolls-Royce Condor

|-See also:-Bibliography:* Lumsden, Alec. British Piston Engines and their Aircraft. Marlborough, Wiltshire: Airlife Publishing, 2003. ISBN 1-85310-294-6.-External links:*...

 IIIA water-cooled in line 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

Hubert Broad

Captain Hubert Standford Broad MBE AFC was an English First World War aviator and notable sports and test pilot.-Early life:Broad was born in Watford on 18 May 1897 the son of Thomas and Amelia Broad. In 1901 when Broad was three the family were living at Aston Lodge, St Johns Road in Watford his...

 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

RAF Martlesham Heath

RAF Martlesham Heath is a former Royal Air Force airfield in England. The field is located 1½ miles SW of Woodbridge, Suffolk.- RFC/RAF prewar use:Martlesham Heath was first used as a Royal Flying Corps airfield during World War I...

 for successful airworthiness tests early in 1926, with the Certificate of Airworthiness awarded on 23 April 1926. By then, though Imperial Airways

Imperial Airways

Imperial Airways was the early British commercial long range air transport company, operating from 1924 to 1939 and serving parts of Europe but especially the Empire routes to South Africa, India and the Far East...

 had decided no longer to transport passengers in single-engined types for safety reasons and the sole Highclere was transferred to RAE Farnborough on 7 March 1926 for experimental work. On 7 November 1926 it was loaned to Imperial Airways at Croydon Airport

Croydon Airport

Croydon Airport was an airport in South London which straddled the boundary between what are now the London boroughs of Croydon and Sutton. It was the main airport for London before it was replaced by Northolt Aerodrome, London Heathrow Airport and London Gatwick 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 engines.

Specifications