DeHavilland DH-4
| Airco DH.4 | |
|---|---|
 |
|
| DH.4 above the clouds in France | |
| Role | Light bomber / General purpose |
| Manufacturer | Airco |
| First flight | August 1916 |
| Introduction | March 1917 |
| Retired | 1932 (United States Army) |
| Primary users | United Kingdom United States |
| Number built | 6295, of which 4846 were built in the United States. |
| Unit cost |
$11,250
|
| Variants | DH9, DH9A, Dayton-Wright Cabin Cruiser |
The Airco DH.4 was a British two-seat biplane day bomber of World War I. It was designed 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 United States, for service with the American forces in France.
The DH.4 was tried with several engines, of which the best was the 375 hp (280 kW) Rolls-Royce Eagle engine. Armament and ordnance for the aircraft consisted of one 0.303 in (7.7 mm) Vickers machine gun for the pilot and one 0.303 in (7.7 mm) Lewis gun on a Scarff ring mounting for the observer. Two 230 lb (100 kg) bombs or four 112 lb (51 kg) bombs could be carried. The DH.4 entered service on 6 March 1917 with No. 55 Squadron in France.
The DH.4 was designed by Geoffrey de Havilland as a light two-seat day bomber powered by the new Beardmore Halford Pullinger (BHP) engine. The prototype first flew in August 1916, powered by a prototype BHP engine rated at 230 hp (170 kW). While the DH.4 trials were promising, the BHP engine required major redesign before entering production, and the Rolls-Royce Eagle engine was selected as the DH.4's powerplant. The first order for 50 DH.4s, powered by 250 hp (186 kW) Eagle III engines was placed at the end of 1916.
The aircraft was a conventional tractor two bay biplane of all-wooden construction. The crew of two were accommodated in widely spaced cockpits, separated by the fuel tank. It was armed with a single forward-firing synchronised Vickers machine gun and one or two .303 in (7.7 mm) Lewis guns fitted on a Scarff ring fired by the observer. A bomb load of 460 lb (210 kg) could be fitted to external racks. While the crew arrangement gave good fields of view for the pilot and observer, it caused communication problems between the two crew members, particularly in combat, where the speaking tube linking the cockpits was of limited use.
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