De Havilland DH.34

infobox Aircraft
name = D.H.34
type = Airliner
manufacturer = de Havilland

---

caption =
designer = Geoffrey de Havilland
first flight = 1922
introduced = 1922
retired = 1926
primary user = Imperial Airways
more users = Daimler Hire Ltd
Instone Air Line
produced = 1922
number built = 12
unit cost =
developed from =
variants with their own articles = 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.

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 Jackson, A.J. "British Civil Aircraft since 1919 Volume 2". London: Putnam,1973. ISBN 0-370-10107-X.] .

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 . 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) .

Operational history

The DH.34 entered service with Daimler on 2 April 1922 on the Croyden-Paris service Donald, David, ed. "The Encyclopedia of World Aircraft". London: Aerospace Publishing, 1997. ISBN 1-85605-375-X.] . 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 .

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 .

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, and the second aircraft flying over 100,000 miles (160,000 km) without overhaul . Six D.H.34s were lost in accidents during the four years of their operation, several of which accidents were fatal .

Variants

;DH.34:Initial production version. Eleven completed.;DH.34B:Modication of DH.34 with extended upper wing to improve stalling characteristics.

Operators

;USSR
*Dobrolyot;UK
*Daimler Hire Ltd
*Imperial Airways
*Instone Air Line

pecifications (DH.34)

aircraft specifications
plane or copter?=plane
jet or prop?=prop

ref=The Encyclopedia of World Aircraft

crew=Two
capacity=Ten passengers
length main= 39 ft 0 in
length alt= 11.89 m
span main= 51 ft 4 in
span alt= 15.65 m
height main= 12 ft 0 in
height alt= 3.66 m
area main= 590 ft²
area alt= 54.8 m²
airfoil=
empty weight main= 4,574 lb
empty weight alt= 2,075 kg
loaded weight main= 7,200 lb
loaded weight alt= 3,266 kg
useful load main=
useful load alt=
max takeoff weight main=
max takeoff weight alt=
more general=

engine (prop)=Napier Lion
type of prop=12-cylinder broad arrow
number of props=1
power main= 450 hp
power alt= 336 kW
power original=
max speed main= 111 knots
max speed alt= 128 mph, 206 km/h
cruise speed main= 91 knots
cruise speed alt= 105 mph, 169 km/h
never exceed speed main=
never exceed speed alt=
stall speed main= 55 knots
stall speed alt= 63 mph , 101 km/h
range main= 317 nm
range alt= 365 mi, 587 km
ceiling main=
ceiling alt=
climb rate main=
climb rate alt=
loading main= 12.2 lb/ft²
loading alt= 59.6 kg/m²
power/mass main= 0.063 hp/lb
power/mass alt= 0.10 kW/kg
more performance=

armament=

avionics=

ee also

aircontent

related=*DH.29

similar aircraft=*Vickers Vulcan

lists=*List of de Havilland aircraft

see also=

References

External links

* [http://avia.russian.ee/air/england/havilland_dh-34.php Virtual Aircraft Museum]

* [http://www.imperial-airways.com/De_havilland_dh34.html Imperial Airways]