De Havilland DH.34
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| D.H.34 | |
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| Type | Airliner |
| Manufacturer | de Havilland |
| Designed by | Geoffrey de Havilland |
| Maiden flight | 1922 |
| Introduced | 1922 |
| Retired | 1926 |
| Primary users | Imperial Airways Daimler Hire Ltd Instone Air Line |
| Produced | 1922 |
| Number built | 12 |
The de Havilland DH.34 was a single engined British biplane airliner built by de Havilland Aircraft Company in the 1920s. Twelve were built, with the DH.34 serving with Imperial Airways and its predecessors for several years.
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[edit] Design and development
By 1921, enough experience had been gained with operation of the de Havilland DH.18 to realise that aircraft needed to be more efficient to improve the economics of air travel. de Havilland therefore built the 10 passenger DH.29 monoplane, while starting work on the design of the DH.32, a biplane of similar size and capacity to the eight passenger DH.18, but powered by a less powerful but more economical Rolls-Royce Eagle engine. Owing to the urgent need for more capacity, however, work on the DH.29 and DH.32 was stopped and the DH.34 biplane was designed, with a similar fuselage to the DH.29, accommodating 10 passengers.
The DH.34 had a wooden, plywood-clad fuselage, with the cockpit (for two pilots) being positioned ahead of the wings and the passenger cabin. It had two-bay wooden wings and was powered by a Napier Lion engine, which was fitted for inertia starting, avoiding the necessity for hand swinging of the propellor to start the engine [1].
Two DH.34s were ordered by Daimler Hire Ltd, as part of an initial batch of nine aircraft, with the first prototype (registered G-EBBQ) flying on 26 March 1922 [1]. The stalling speed of 63 mph (101 km/h) was considered high and was blamed for a fatal crash in 1923, so extensions were fitted to the upper wings, increasing the wingspan from 51.33 to 54.33 feet (15.65 to 16.56 m) [1].
[edit] Operational history
The DH.34 entered service with Daimler on 2 April 1922 on the Croyden-Paris service [2]. Daimler operated a total of six D.H.34s, four of which were leased from the Air Council, with Instone Air Lines operating a further four, all leased. One aircraft was built to the order of the Soviet airline Dobrolyot [1].
When Imperial Airways was formed on 1 April 1924, by the merger of Daimler Hire, Instone Airways, Handley Page Transport and the British Marine Air Navigation Company, it inherited six D.H.34s, retaining the type in service until 1926 [1].
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[2], and the second aircraft flying over 100,000 miles (160,000 km) without overhaul [2]. Six D.H.34s were lost in accidents during the four years of their operation, several of which accidents were fatal [2].
[edit] Variants
- DH.34
- Initial production version. Eleven completed.
- DH.34B
- Modication of DH.34 with extended upper wing to improve stalling characteristics.
[edit] Operators
[edit] Specifications (DH.34)
Data from The Encyclopedia of World Aircraft [2]
General characteristics
- Crew: Two
- Capacity: Ten passengers
- Length: 39 ft 0 in (11.89 m)
- Wingspan: 51 ft 4 in (15.65 m)
- Height: 12 ft 0 in (3.66 m)
- Wing area: 590 ft² (54.8 m²)
- Empty weight: 4,574 lb (2,075 kg)
- Loaded weight: 7,200 lb (3,266 kg)
- Powerplant: 1× Napier Lion 12-cylinder broad arrow, 450 hp (336 kW)
Performance
- Maximum speed: 111 knots (128 mph, 206 km/h)
- Cruise speed: 91 knots (105 mph, 169 km/h)
- Stall speed: 55 knots (63 mph [1], 101 km/h)
- Range: 317 nm (365 mi, 587 km)
- Wing loading: 12.2 lb/ft² (59.6 kg/m²)
- Power/mass: 0.063 hp/lb (0.10 kW/kg)
[edit] See also
Related development
Comparable aircraft
Related lists
[edit] References
[edit] External links
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