In the very early 1920s, De Havilland recognised the need for increased capacity to improve the economics of passenger transport operations.
The DH29, their ten seat monoplane, had suffered with significant low speed handling issues and so the company opted for a relatively conventional biplane for their next commercial design, the DH34.
The prototype DH34 (G-EBBQ) flew for the first time on 26th March 1922 and was delivered just a few days later to Daimler Hire Ltd who immediately commenced passenger services to Paris which were inaugurated on 2nd April 1922.
Carrying upto 10 passengers, the DH.34s were used heavily on the cross-channel air services, with the fleet flying 8,000 hours in the first nine months of operation with the second aircraft flying over 100,000 miles without overhaul.
The plywood covered fuselage featured an enclosed passenger cabin with two pilots seated immediately ahead of the wings but behind the Napier Lion engine in a side-by-side open cockpit, high up in the nose of the aircraft (so high in fact that a distinctly non-aerodynamic external ladder was provided to allow the crew to reach it). The engines were fitted with inertia starters thus avoiding the necessity for hand-swinging of propellers.
Unusually, the cabin was designed to allow a spare engine to be carried across the rear of the passenger cabin with the unusual shape of the cabin door allowing the engine to be loaded and unloaded. Spare engines were not routine cargo but the facility allowed operators to combine maintenance and service requirements with fare paying flights. A specially-fitted removable 'porthole' on the other side of the cabin allowed the propeller boss to protrude out the side of the aircraft.
A total of eleven DH34s were built with a number of them being modified 'in-service' to DH34B standards with increased wing span and area. The increase in wing area from 590 sq ft to 637 sq ft reduced the landing speed by some 7 mph, without significantly affecting the type’s cruise performance. This modification was intended to lower the landing speed to 70 mph, which was still regarded as high at the time.
In addition to Daimler Hire, the type was flown by Instone Air Line who used their four aircraft on combined European destinations including Amsterdam, Brussels, Cologne and Berlin.
Twelve DH34 were allocated construction numbers, although it is believed that the final one, G-EBCY, may not have been completed. Although they were very successful and reliable in service, five were destroyed in accidents. One aircraft was exported to Russia.
Six DH34 were passed to Imperial Airways on its formation in 1926, but the Company decided to select multi-engine aircraft for passenger operations and consequently the remaining DH34s were withdrawn from service at the end of March 1926 before being dismantled at Croydon.
|(DH34 and DH34B unless otherwise noted)|
|Powerplant||One 450 hp Napier Lion engine|
|Span||DH34 51 ft 4 in; DH34B 54 ft 4 in|
|Maximum Weight||7,200 lb|
|Capacity||Two pilots in an open cockpit and seats for nine passengers in an enclosed cabin|
|Maximum Speed||128 mph|
|Cruising Speed||105 mph|
Variants & Numbers Built
|DH34||Production standard (12, of which 11 aircraft are known to have been completed)|
|DH34B||Three aircraft modified with increased wing span and area (G-EBBT, ‘BBX, ‘BBY)|