|Designer||Geoffrey de Havilland|
|First flight||Aug 1916 |
|Introduction||6 March 1917 [note 1]|
|Primary users|| U.K. (RFC/RAF)|
|Number built||1449 British, 4346 to 4846 USA[note 2]|
|Wingspan||12.9 m (42 ft 5 in) |
|Engine||250-375hp Rolls-Royce Eagle inline or|
400hp Liberty inline [note 3]
|Armament||1-2×sync. fixed Vickers [note 4] and|
1-2× flexible rear Lewis
200–210 kg (450–460 lb) of bombs [note 5]
|Ammo||600 (Vickers), 6-10 drums of 47-97 rounds (Lewis)|
The Airco D.H.4 was the first British plane designed specifically as a day-bomber. While it was originally designed for the 160hp Beardmore or 230hp BHP engine, but it is perhaps fortunate that the BHP production was delayed and the 250hp Rolls-Royce Eagle was available instead. The Eagle was an excellent engine and it only got better with successive marks, culminating with the 375hp Eagle VIII. №55 Squadron received the first full batch of D.H.4s and arrived in France in March 1917.
Shortages of Rolls-Royce engines forced experiments with many other types, including the 200hp B.H.P. (a development from the early Beardmore), the 200hp Siddeley Puma, the 200hp Galloway Adriatic, Fiat, and the 200hp R.A.F.3a. Batches of D.H.4s were built with these various engines, but pilots greatly preferred the Rolls-Royce.
Westland-built D.H.4s for the RNAS, and they fitted twin Vickers guns for the pilot instead of the normal single fixed gun. When introduced the D.H.4 outperformed all other twin-seaters of its class and could outrun many enemy fighters.
The D.H.4's greatest weak spot was the long distance between the pilot and observer, making cooperation difficult, a fault that was corrected in the Airco D.H.9. DH4s served from March 1917 through to the Armistice, performing bombing, observation, photography, anti-Zeppelin, and anti-submarine duties. 
Overall, the D.H.4 was one of the great designs of World War One. It served on the Western Front, Italy, Aegean, Macedonia, Palestine, Mesopotamia, and during the Russian Revolution. An RNAS DH4 took down Zeppelin L.70 in August 1918. Belgium equipped six escadrilles with D.H.4s.
After America's entry into the Great War, there were high hopes that the country's industrial might could be turned to aircraft manufacturing. Things never go as easily as expected, and the development of a two-seater based on the British DH4 with the 400hp Liberty engine faced repeated delays. After several delays to both the airframe and engine, Fisher, Standard, and Dayton-Wright built DH4s. While 1,213 were shipped to France, only 196 saw front-line combat.
Though the DH4 design had been already eclipsed by its first American use in July 1918, the US Air Service did not have alternatives. The DH4 holds the distinction of being the only fully American-built land warplane to see action in the war.
An improved version, the D.H.4B, was created but it was too late for the war. The D.H.4B fixed problems in the fuel system, moved the fuel tank so that the crew could sit closer together (in the manner of the D.H.9) and moved the wheels further forward to reduce tip-over accidents on poorly-prepared airfields. After the war, a wide variety of minor variants were based on the D.H.4B, including the steel-framed D.H.4M. D.H.4s continued to serve with the American Air Service through the 20's and they were used for Air Mail delivery though 1931. 
|Engine||Speed||Climb||Svc. Ceiling||Abs. Ceiling||Endurance||Propeller Diam.|
|250hp Eagle III||188 km/h (117 mph) to|
192 km/h (119 mph)
|2,000 m (6,500 ft) in 8:55|
3,000 m (10,000 ft) in 16:25
|4,900 m (16,000 ft)||3:30||2.67 m (8 ft 9 in)|
|375hp Eagle VIII[note 6]||220 km/h (137 mph) to|
230 km/h (143 mph)
|2,000 m (6,500 ft) in 5:09|
3,000 m (10,000 ft) in 9:00
|6,700 m (22,000 ft)||6,700 m (22,000 ft) to|
7,200 m (23,500 ft)
|3:45||3.10 m (10 ft 2 in)|
|400hp Liberty V-1650||201 km/h (125 mph)||3,000 m (10,000 ft) in 14:00||4,800 m (15,800 ft)||5,900 m (19,500 ft)||3:00|
For more information, see Wikipedia:Airco DH.4.
Timeline [note 7]
|Version||Availability||Maneuver||Damage||Dmg Points||Max Alt.||Climb||Points|
Miniatures and Models
- Ares: WGF204A 50th Sqn AEF; WGF204B Cotton/Betts; WGF204C Bartlett/Naylor
- Plastic Kit: Valom
- Metal kit: Red Eagle
- Wings of War: WW08J Cadbury/Leckie; WW08K USA; WW08L Clayburn Atkey
- Metal Cast: Goblintooth/H.A./MSD UKG-09
- Metal kit: Heroics & Ros GWA124
- Shapeways: Kampfflieger
- Shapeways: Reduced Aircraft Factory
- While the first American DH4s arrived in May 1918, it was not until 2 August 1918 that the reworked machines were ready for their first combat patrol.
- By the Armistice, 1213 DH4s had been delivered to France.
- Also fitted to production machines were the 230hp B.H.P, 200hp R.A.F. 3a, and 260hp Fiat engines.
- American-built machines used Marlin or Browning synchronized machine guns.
- The American DH4 carried up to 150 kg (322 lb) of bombs.
- In Aug 1918, №217 believed it was the only squadron full equipped with Eagle VIII D.H.4s. So they were not very common, even late in the war.
- British usage numbers are approximate, derived from the squadron histories.
- Updated card
- Lamberton, p.36.
- Bruce'65, p.4.
- Bruce'69, p.166.
- Bowers'66, p.6.
- Angelucci, p.78.
- Bruce'65, p.12.
- Bowers'66, p.4.
- Lamberton, pp.214-215.
- Angelucci, p.71.
- Bowers'66, p.7.
- Kelly, p.229.
- Bruce'65, p.5.
- Bruce'65, p.10.
- Bowers'66, pp.7-10.
- Bruce'69, pp.178-179.
- Munson, p.60.
- Bruce'65, p.9.
- Bowers'66, p.12.
- Philpott'13, pp.379-444.
- Enzo Angelucci, ed. The Rand McNally Encyclopedia of Military Aircraft, 1914-1980. New York: The Military Press, 1983 edition. ISBN 0-517-41021-4.
- Peter M. Bowers, Profile Publications 97: The American D.H.4. Great Britain: Profile Publications, Ltd., 1966.
- J.M. Bruce. British Aeroplanes 1914-18. Great Britain, Funk & Wagnalls, 1957, 1969. ISBN 0370000382
- J.M. Bruce, Profile Publications 26: The de Havilland D.H.4. Great Britain: Profile Publications Ltd., 1965.
- Jon Guttman, Windsock Datafile 101: American DH4. Great Britain: Albatros Publications Ltd., 2003. ISBN 1-902207-56-4
- Kevin Kelly, "Belts and Drums: A Survey of First World War Aircraft Ammunition Totals". Over the Front, Vol. 5, No. 3, Autumn 1990. Walsworth Publishing Co, Inc. and The League of World War I Aviation Historians.
- Kenneth Munson, Bombers: Patrol and Reconnaissance Aircraft, 1914-1919. New York: The MacMillan Company, 1968, Blandford Press Ltd. ISBN 978-0753721711
- W.M. Lamberton and E.F. Cheesman, Reconnaissance & Bomber Aircraft of the 1914-1918 War. Great Britain: Harleyford Publications Ltd., 1962. ISBN 9780900435027
- Ian Philpott, The Birth of the Royal Air Force. Great Britain: Pen & Sword Books Limited, 2013. ISBN 978-1-78159-333-2