Aircraft Manufacturing Company Ltd / Airco DH 4 / O2B-1

Aeromarine DH-4B

 

Two were fitted out experimentally with extra fuel tanks, enough to give 14 hours' flying, and were intended to carry out a special photographic reconnaissance of shipping in the Kiel Canal. This mission never took place, but the two D.H.4s were later fitted instead with twin over-wing Lewis guns and used for night fighting.

The DH4 was withdrawn from RAF service soon after the Armistice, and in the early postwar years many were supplied to the air forces of Belgium (where SABCA also built 15 in 1926), Canada, Chile, Greece, Persia, New Zealand, South Africa and Spain. Some remained in service until the early 1930s, and others were converted for civil use in the 1920s.

Production in Britain totalled 1450, built by by Airco and under sub-contract by F.W. Berwick and Company, Glendower Aircraft Company, Palladium Autocars Ltd, The Vulcan Motor and Engineering Company, Waring & Gillow Ltd, and the Westland Aircraft Works. At the end of the First World War 548 were still in service.

Almost all of the delays were the result of engine manufacturers not being able to deliver their engines on time, and when they did, Airco discovered that some of the engines had had modifications made which resulted in them having to alter the aircraft’s airframes to accommodate them. Even with all the delays, the government decided to supply the Russian Government with fifty DH.4s. These models were to be fitted with the Fiat A.12 engine. The Russian winter had set in and the Bolshevik revolution was about to break out, so it was impossible to deliver the aircraft. Immediately, the RFC used them to supplement their bomber force. The British government agreed with the Russians to replace the aircraft with an additional twenty-five in the spring of 1918, but because of the outcome of the revolution in Russia this never happened.

Rolls-Royce engine production could not keep pace with this, resulting in several batches of D.H.4s being fitted with such alternative powerplants. Other than the Rolls-Royce III, IV or Eagle, these included the 149-kW (200-hp) R.A.F.3a, 172-kW (230-hp) Siddeley Puma, Adriatic (200-hp), and 194-kW (260-hp) Fiat A-12.

Experimental engine installations included a 224-kW (300-hp) Renault l2Fe, 239-kW (320-hp) Armstrong Siddeley Jaguar I, 263-kW (353-hp) Rolls-Royce ‘G’, 298-kW (400-hp; Sunbeam Matabele, and a Ricardo-Halford supercharged engine. lncreasing engine powers required larger diameter propellers, steadily reducing clearance between the propeller tip and the ground, and resulted in the main landing gear units being extended sufficiently to cater for future growth.

Highest performance was achieved with the Rolls-Royce Eagle VIII (375-hp), which gave the D.H.4 a top speed of 230 km/h (143 mph).

Armament of the standard D.H.4s consisted of a fixed forward-firing Vickers machine-gun that was synchronised by a Constantinesco interrupter gear; the observer/gunner had one or two Lewis guns mounted on a Scarff ring. Underfuselage and underwing bomb racks had a maximum capacity of 209 kg (4601b). Aircraft built by Westland Aircraft for the RNAS had twin Vickers machine-guns for the pilot, and the rear Lewis guns were on a pillar mounting. Two examples of the D.H.4 were modified to mount a Coventry Ordnance works (C.O.W.) quick-firing gun, which fired a 0.68-kg (1.5-lb) shell. Mounted to fire almost vertically upward, this gun as intended for attacks on German Zeppelins; but by the time they were ready for service, Zeppelin raids on Britain had ended.

The United States possessed no combat-worthy aircraft upon entry into World War I in 1917 and selected the DH-4 because of its comparatively simple construction and it was well-suited to the 400-horsepower Liberty V-12 engine.

In the summer of 1917 a pattern aircraft had been fitted with a 400 hp Liberty 12 engine and the US govern-ment ordered more than 12,000 'Liberty Planes', although 7502 were cancelled after the Armistice. A total of 4846 were completed by Dayton Wright (3106), Fisher Body Division of General Motors (1600) and Standard Aircraft Corporation (140) and the Atlantic Aircraft Corp, New Jersey, and Boeing Airplane Corp, Seattle, before production ceased at the war’s end in 1918.

By war's end, 13 Army Air Service squadrons, five of them bomber squadrons, were equipped with them (from August 1918). In addition, four combined Navy-Marine squadrons of the US Naval Northern Bombing Group were flying DH-4s along the Belgian coast. Of the 4,346 DH-4s built in the United States, 1,213 were delivered to France, but of those only 696 reached the Zone of Advance. In the postwar period, the DH-4 was the principal aircraft used by the U.S. Government when airmail service began in 1918.

The Americans designated the initial version the DH4A, but it was obsolescent by the time it entered US service, having had to be reworked to suit it to US production techniques, and the improved DH-4B was ready too late (October 1918) to take its place on the Western Front. American-built DH-4As were armed with two Marlin or Browning machine-guns in the front and two Lewis guns in the rear cockpit, and could carry up to 150 kg (332 lb) of bombs. After the war, 283 of the Army's DH-4As were transferred to the US Navy or Marine Corps as observation or transport planes until 1932.

Aeromarine converted 125 DH-4B under contract for de Havilland, first flown in 1917. One Aeromarine DH-4B conversion example was specially tested at Wright Field. Possibly same as Whitbeck Special.

 
Aeromarine DH-4B

The NASM collection has the prototype American-built DH-4, manufactured by the Dayton-Wright Airplane Company. This airplane was used in more than 2,600 experiments until its retirement in April 1919. It was also the airplane in which Orville Wright made his last flight as a pilot in 1918.

The career of the D.H.4 was to continue long After the Armistice of 1918, war surplus examples went to the Belgian, Greek, Japanese, and Spanish air forces, with American-built machines continuing to serve with the United States Army Air Corps and with many Latin American countries. In 1924 the Mexican government procured a number of US-built D.H.4B bombers. Large num-bers of varants appeared in the USA during the early post-war years, these being conversions of ex-military aircraft, and many pioneering flights were made wth them. Two USAAC DH-4Bs were used in the first successfu experiments of inflight refuelling.

Variants:
Airco D.H.4A
Designation of British post-war civil conversions with an enclosed two-seat passenger cabin formed from the aft cockpit

DH-4A
Designation of US-built version with revised and increased capacity fuel system.

DH-4B/-4C/-4L/-4M/-4Amb/-4Ard
Blanket desgnation covering a large numner of US post-aver variants; for example, DH-4B varianns included DH-4B, DH 4B-1, DH-4BD etc., to the extent of some 60 versions, many of them experimental.

Airco D.H.4R
Designation of a singe racing version converted by clipping the lower wings and installing a 336 kW (450-hp) Naper Lion inline piston engine

Specifications: