Airco DH.4
Template:Infobox Aircraft The Airco DH.4 was a British two-seat biplane day-bomber of the First World War. It was a design by Geoffrey de Havilland (hence "DH") for Airco, and was the first British two seat light day-bomber to have an effective defensive armament. It first flew in August 1916 and entered service with the Royal Flying Corps (RFC) in March 1917. The majority of DH.4s were actually built as general purpose two seaters in the USA, for service with the American forces in France.
The DH.4 was tried with several engines - of which the best was the 375 hp Rolls-Royce Eagle engine. Armament and ordnance for the aircraft consisted of one 0.303 in Vickers machine gun for the pilot and one 0.303 in. Lewis machine gun on a Scarff ring mounting for the observer. Two 230 lb bombs or four 112 lb bombs could be carried. The DH.4 entered service on 6 March 1917 with No. 55 Squadron in France.
Development
The DH.4 was designed by Geoffrey de Havilland as a two seat day bomber (light bomber) powered by the new BHP engine. The prototype first flying in August 1916, powered by a prototype BHP engine rated at 230 hp. While the DH.4 trials were promising, the BHP engine required major redesign before entering production. It was therefore decided to fit the DH.4 with the Rolls-Royce Eagle engine, the first order for 50 DH.4s, powered by 250 hp Eagle III engines was placed at the end of 1916.
As production continued, DH.4s were fitted with Eagle engines of increasing power, settling on the 375 hp Eagle VIII, which powered the majority of front line DH.4s by the end of 1917. Because of the chronic shortage of Rolls Royce aero engines in general, and Eagles in particular, alternative engines were also investigated, with the BHP (230 hp), the Royal Aircraft Factory RAF3A (200 hp), the Siddeley Puma (230 hp) and the 260 hp Fiat, all being used in production aircraft. None of these engines could match the Rolls-Royce Eagle - however there were simply not enough Eagles available.
In American production, the DH.4 proved suitable for the new Liberty engine - although this produced a slightly inferior performance to the Eagle it was also to eventually power the British DH.9A.
Production
Production was by Airco, F.W. Berwick and Co, Glendower Aircraft Company, Palladium Autocars, Vulcan Motor and Engineering, and the Westland Aircraft Works in the UK. SABCA of Belgium made fifteen. A total of 1,449 aircraft were made in the UK for the RFC and RNAS.
In the United States, the Boeing Airplane Corporation, Dayton-Wright Aeroplane Company, The Fisher Body Corporation, and the Standard Aircraft Corporation produced the DH.4 with the Liberty L-12 engine for the American air services. A total of 9,500 DH.4s were ordered from American builders, of which 1,885 actually reached France during the war.
After the war a number of firms, most significantly Boeing, were contracted byt he US Army to remanufacture surplus DH.4s to DH.4B standard. Known by Boeing as the Model 16, deliveries of 111 aircraft from this manufacturer took place between March and July 1920, with 50 of them returned for further refurbishments three years later.
In 1923, the Army ordered a new DH.4 variant from Boeing, characterised by a fuselage of fabric-covered steel tube in place of the original plywood structure. These three prototypes were designated DH-4M-1 (M for modernized) and were ordered into production alongside the generally similar DH-4M-2 developed by Atlantic Aircraft. Twenty-two of the 163 DH-4M-1s were converted by the Army into dual-control trainers (DH-4M-1T) and a few more into target tugs (DH-4M-1K). Thirty of the aircraft ordered by the Army were diverted to the Navy for Marine Corps use, these designated 02B-1 for the base model, and O2B-2 for aircraft equipped for night and cross-country flying.
Service history
The DH.4 entered service with the RFC in January 1917, first being used by No. 55 Squadron. More squadrons were equipped with the type to increase the bombing capacity of the RFC, with two squadrons re-equipping in May, and a total of six squadrons by the end of the year. As well as the RFC, the RNAS also used the DH.4, both over France and over Italy and the Aegean front.
The DH.4 proved a huge success and was considered the best single-engined bomber of the First World War. With its reliability and impressive performance - even when fully loaded with bombs - the type proved highly popular with its crews. The Airco DH.4 was easy to fly, and especially when fitted with the Roll Royce Eagle engine, its speed and altitude performance gave it a good deal of invulnerability to German fighter interception, so that the DH.4 often did not require a fighter escort on missions. One design drawback was the distance between pilot and observer, caused by the fuel tank placed between the pilot and observer, making communication between the crew members difficult. There was some controversy (especially in American service) that this placement of the fuel tank was inherently unsafe. In fact most contemporary aircraft were prone to catching fire in the air. In any case the arrangement of fuel tank and cockpits was rectified in the otherwise inferior D.H.9.
Despite its success, numbers in service with the RFC actually started to decline from spring 1918, mainly due to a shortage of motors, and production switched to the DH.9, which was expected to give greater performance, but turned out to be disappointing, being inferior to the DH.4. It was left to the further developed D.H.9A, with the American Liberty engine to finally replace the DH.4.
At the time of entry into the war the American Air Service lacked any aircraft suitable for front line war service. They therefore procured various aircraft from the British and French, one being the DH.4. As the DH.4a, it was manufactured mostly by Dayton-Wright and Fisher Body for service with the United States from 1918. The powerplant was a Liberty L-12 of 400 hp and it was fitted with two .30 inch Marlin machine guns in the nose and two .30 inch Lewis machine guns in the rear and could carry 322 pounds of bombs. The heavier engine reduced performance a little compared with the Rolls Royce powered version, but as the "Liberty Plane" it became the Americans' standard general purpose two seater, and on the whole was fairly popular with its crews. The type flew with 13 U.S. squadrons by the end of 1918.
Variants
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- DH.4 : Two-seat day bomber biplane.
- DH-4 : Two-seat day bomber biplane. Built in the United States.
- DH.4A : Civil version. Built in the United Kingdom. Two passengers in glazed cabin behind pilot.
- DH-4A : Civil version. Built in the United States.
- DH-4B :
- DH-4B-1 :
- DH-4BD :
- DH-4C :
- DH-4L :
- DH-4M :
- DH-4Amb :
- DH.4R : Single seat racer - 450 hp Napier Lion engine.
- DH-4M-1 - postwar version by Boeing (Model 16) with new fuselage, designated O2B-1 by Navy
- DH-4M-1T - trainer conversion
- DH-4M-1K - target tug conversion
- O2B-2 - cross-country and night-flying conversion for Navy
- DH-4M-2 - postwar version by Atlantic
Civil operators
- Aircraft Transport and Travel Limited
- Handley Page Transport
- Imperial Airways
- Instone Air Line
- SNETA
Military operators
Specifications (DH.4 - Eagle VIII engine)
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Data from The British Bomber since 1914[1]
General characteristics
- Crew: 2
Performance
- Endurance: 3¾ hr
- Climb to 10,000 ft: 9 min
Armament
- Forward-firing Vickers machine gun
- Lewis gun on Scarff ring at rear
- 460 lb (209 kg) of bombs
References
Related content
Related development Airco DH.9 - Airco DH.9A