Airco DH4

 

The Aircraft Manufacturing Company (Airco) DH4 (No3696) was a two-seat biplane day bomber of the first World War.  It first flew at Hendon in August 1916, with its designer Geoffery de Havilland at the controls.  After testing trials at Upavon and later at Martlesham Heath, it entered Royal Flying Corps (RFC) service on 6th March 1917, with No. 55 Squadron based in France.

 

The Airco DH4 had open cockpits, with the crew being separated by the fuel tank installed between them in the fuselage, which meant that a speaking tube was required for communications.

 

It was the first Day-Bomber to have defensive armament, with a forward firing Vickers 0.303 mm machine gun for use by the pilot, plus a 0.303 Lewis gun (sometime 2 guns) fitted on a Scarff ring for the observer. Two 230lb or four 112lb bombs could also be carried.

 

 

Early aircraft featured fairly short undercarriage legs, which resulted in a low propeller clearance on take-off, together with creating difficulties when operating from rough ground. The undercarriage struts were therefore lengthened on all later production aircraft.

 

Power was initially provided in the prototype by the 230hp BHP engine, although several other engine types such as the Siddeley Puma, Fiat and RAF 3A were later fitted. Of these alternative engines, the 375hp Rolls-Royce Eagle VIII is regarded as being the most successful.  Unfortunately, Rolls-Royce Eagle engines were in short supply and so production units built U.S. aircraft were powered by the 400 hp Liberty L-12 engine (which was later adopted for the Airco DH9A model) which was also used in American automobiles.

 

A later US-built derivative, the DH4M featured a fabric-covered steel tube fuselage.

 

 

The Airco DH4 proved very popular in service, not least for its speed and climb performance, manoeuvrability and pleasant flying characteristics.

 

1,449 Airco DH4 aircraft were built in the UK, some 915 of which were constructed at the Aircraft Manufacturing Works at the Hyde in Hendon. 

 

A further substantial number (4,846 from planned orders of up to 9,500) were built in the USA by Boeing, Dayton-Wright, Fisher Body Company and Standard Aircraft. Rather strangely however, 15 aircraft were also made by Sociétés Anonyme Belge de Constructions Aéronautiques (SABCA) in Belgium during 1926, long after the aircraft retired from military service.

 

In USA, the type was designated Airco DH4A and Airco DH4B, with a wide range of designations applied to various mainly experimental developments. In the Airco DH4B version, the pilot’s cockpit was moved to the rear to be adjacent to that of the gunner.

 

 

British sub-contract orders were also placed with F.W. Berwick, Glendower Aircraft, Palladium Autocars Ltd and Vulcan Motor & Engineering, as well as Westland Aircraft Works. It was also proposed that a factory be set up in Russia to build Airco DH4s although the Russian Revolution of October 1917 resulted in these plans being abandoned.

 

Many Airco DH4s were used for experimental flying, such as in engine test work, both in the UK and the USA. Post-war, a single seat racing variant with cropped lower wings (Airco DH4R) won the 1919 Aerial Derby air race. 

 

 

The Airco DH4 was employed in a large number of roles, with variants that included crop-duster, ambulance and target-tug adaptations, as well as numerous training and commercial developments.

 

After the war, the type, and its derivatives, played an important role in initiating commercial passenger and Air Mail services in the UK and Australia as well as being particularly important to the US Postal Department. The majority of the US Mail aircraft were actually converted to single seaters, with the mail carried in a watertight compartment in the space previously occupied by the front cockpit.

 

 

The Airco DH4A commercial variant had a small glazed cabin in the rear fuselage in which two passengers could be seated. Operators included AT & T Ltd, who operated the service between Hounslow Heath Aerodrome and Paris Le Bourget. Other aircraft were operated by SNETA (Belgium), Handley Page Ltd and Instone Air Lines. In the southern hemisphere, the emerging Australian concern Qantas used the Airco DH4A for its first airmail service in 1922.

 

The DH4 eventually formed the basis for the Airco DH9 and Airco DH9A, of which a further total of more than 6,000 aircraft were built.