De Havilland DH.34

de Havilland

Industry	Aerospace
Founded	1920s
Headquarters	United Kingdom

The de Havilland DH.34 was a British single-engine biplane airliner developed by the de Havilland company during the 1920s. A total of twelve units were manufactured, with the DH.34 operating for several years under Imperial Airways and its antecedents.

Design and development

By 1921, operational insights gained from the de Havilland DH.18 highlighted the need for more efficient aircraft to enhance the financial viability of commercial air travel. In response, de Havilland constructed the ten-passenger DH.29 monoplane and initiated work on the DH.32, a biplane comparable in size and capacity to the eight-passenger DH.18 but powered by a less potent yet more fuel-efficient Rolls-Royce Eagle piston engine. Feedback from prospective operators led to halting development of both the DH.29 and DH.32, prompting the design of a new biplane airliner—the DH.34—which featured a fuselage similar to that of the DH.29 and accommodated nine passengers.

The DH.34 incorporated a wooden fuselage covered with plywood, positioning a two-pilot cockpit forward of the wings and passenger compartment. Its structure included two-bay wooden wings and was powered by a Napier Lion engine equipped with inertia starting, eliminating the need for manual propeller swinging during engine startup. A distinctive aspect of its design was the capacity to carry a complete spare engine aboard, mounted transversely over the rear section of the passenger cabin. To facilitate this, the cabin door was uniquely shaped to allow engine loading and unloading, while an adjacent 'porthole' on the opposite side could be removed to permit the propeller boss to extend outside the fuselage. Although routinely transporting spare engines was impractical due to payload limitations affecting passenger capacity, operators utilized this feature to rapidly deliver replacement engines to aircraft experiencing mechanical failures.

An initial order from Daimler Airway included two DH.34s as part of a nine-aircraft batch, with the prototype (registration G-EBBQ) making its maiden flight on 26 March 1922. The aircraft's stall speed of 63 mph (101 km/h) was deemed excessive and implicated in a fatal accident in 1923; consequently, extensions were added to the upper wings, increasing their span from 51 ft 4 in (15.65 m) to 54 ft 4 in (16.56 m). This modification resulted in the updated variant being designated as the DH.34B.

Operational history

The inaugural DH.34 was handed over to Daimler on 31 March 1922 and commenced operations on the Croydon-Paris route starting 2 April 1922. Daimler managed a fleet of six D.H.34 aircraft, four of which were leased from the Air Council, while Instone Air Line operated an additional four, all under lease agreements. Additionally, one unit was constructed specifically for the Soviet carrier Dobrolyot.

Following the establishment of Imperial Airways on 1 April 1924—resulting from the consolidation of Daimler Airway, Instone Air Line, Handley Page Transport, and the British Marine Air Navigation Company—the airline inherited six D.H.34s. The type remained active until March 1926, when Imperial Airways discontinued its use, shifting focus from single-engine to multi-engine aircraft. The Lion engines from the DH.34s were subsequently repurposed for Imperial’s Handley Page W.10 fleet.

The DH.34s were extensively deployed on cross-Channel routes, accumulating approximately 8,000 flight hours within their initial nine months of service. Notably, one aircraft logged over 100,000 miles before requiring an overhaul. Throughout their four years in operation, six D.H.34s were involved in accidents, several of which resulted in fatalities.

In November 1923, the previously strong safety record of the English Air Service was marred by a severe incident on the London-Birmingham route. A DH.34 carrying three passengers experienced difficulties near Ivinghoe Beacon by Leighton Buzzard before abruptly entering a high-speed nose dive and crashing, causing total loss of life onboard.

Variants

DH.34

Standard production model with eleven units completed.

DH.34B

Modified version featuring an extended upper wing designed to enhance stall performance.

Operators

Template:USSR

• Dobrolyot

Template:UK

• Daimler Airway
• Imperial Airways
• Instone Air Line

Accidents and incidents

• On 13 August 1922, Instone Air Line’s G-EBBW made an unscheduled landing at Marden Airfield due to a ruptured oil pipe. The plane was repaired and subsequently returned to Croydon.
• On 30 August 1923, G-EBBQ—the first registered DH.34 operated by Daimler Hire—crashed at Croydon Airport during a flight to Antwerp and was declared a total loss; no injuries occurred.
• On 14 September 1923, Daimler Airway’s G-EBBS crashed near Ivinghoe Beacon while en route from Croydon to Manchester, resulting in the deaths of all five occupants.
• On 24 December 1924, Imperial Airways’ G-EBBX crashed shortly after departing Croydon and caught fire, killing the pilot along with all seven passengers aboard.

Specifications (DH.34)

File:De Havilland DH.34 3-view Flight January 5, 1922.jpg

Three-view illustration of the De Havilland DH.34 from Flight, January 5, 1922

References

Bibliography

• Donald, David, editor. The Encyclopedia of World Aircraft. London: Aerospace Publishing, 1997. ISBN 1-85605-375-X.
• Jackson, A. J. British Civil Aircraft since 1919: Volume 2. London: Putnam, 1973. ISBN 0-370-10010-7.
• Jackson, A. J. De Havilland Aircraft since 1909. Third edition. London: Putnam, 1987. ISBN 0-85177-802-X.
• Jackson, A. J. "The end of a famous aeroplane." Aeroplane Monthly, July 1979, vol. 7, no. 7, pp. 346–349.
• Stroud, John. "Wings of Peace No 9: de Havilland D.H.34." Aeroplane Monthly, June 1984, vol. 12, no. 6.
• "The D.H. Type 34 Commercial Biplane: Napier 'Lion' Engine." Flight, January 5, 1922, vol. XIV, no. 640, p. 4.
• "The D.H. Type 34 Commercial Biplane: First Machines Ready." Flight, March 30, 1922, vol. XIV, no. 692, pp. 185–188.
• Warner, Edward P. "Les avions de ligne au banc d'essai en 1921." Le Fana de l'Aviation, May 2008, no. 462, pp. 44–55.