Airco DH.4 Biplane History
The Airco DH.4 was designed for Airco by Geoffrey de Havilland as a twin seat light daylight bomber of all wood airframe construction for use by the Royal Flying Corps in WW1. The overall design proved to be highly successful, especially when powered by the Rolls Royce Eagle engine. The only real criticism of the design was the the fuel system, which some thought represented an unnecessary potential fire risk. Although the Airco DH.4 was designed as a bomber, the majority produced were in fact built as utility aircraft, as the design proved to be both rugged and reliable.

The Airco DH.4 in WW1
Driven by the needs of WW1, knowledge of aircraft design advanced by leaps and bounds in just a few years. When  Geoffrey de Havilland designed this aircraft in 1916 the major lessons of aircraft design had been learnt. The DH.4 first flew in August 1916 and entered service with the RFC (Royal Flying Corps) in France during  March 1917. The aircraft soon proved itself to be an outstanding aircraft and arguably the best single engine bomber of WW1. When America entered the war, they did so without any aircraft designs equal to those in use by either side. They soon realised that it would be an ideal aircraft for their own air force and acquired the rights to manufacture it in the United States. Using numerous companies, including Boeing, they built 9,500 DH.4's. 20% of the US produced Airco DH.4 biplanes were sent to Europe, the rest were used for numerous other duties within the US, Indeed the type was so well thought of that the United States Army did not retire it's last one until 1932.

The Airco DH.4 Design and Production
When Geoffrey de Havilland designed the Airco DH.4, he made the unusual choice of placing the main fuel tank between the pilot and co pilot. This had two obvious advantages; firstly the pilot was not as far back in the aircraft, which gave better forward visibility over the rather large and long engine, making take offs and landings easier. Secondly the increased distance between the pilot and observer reduced "blind-spots".

The central location of the main fuel tank also came with a few disadvantages. The fuel system was a pressurised system, and while this eliminated fuel pump issues it meant any leaks were also under pressure. This included the main fuel tank which, if holed would rapidly leak copious amounts of aviation fuel close to the pilot and observer. This was a point in time when aircraft fires were all too common and created a lot of criticism. Later models of the Airco DH.4 abandoned the pressurised fuel tank system and instead used a propeller slip stream powered fuel pump.

Several engines were tried in the Airco DH.4. The Rolls Royce Eagle proved to be the best, with the American Liberty L-12 being a close second. A total of approximately 6,200 DH.4's were produced, about 25% in the UK, most of the remainder in the US.

Various scale models, model kits and plans of this aircraft have been available in the market place.

Airco DH.4 Biplane Specifications:

Airco DH.4 Crew: Pilot and observer
Airco DH.4 Length: 30 ft 8 in (9.35 m)
Airco DH.4 Wingspan: 43 feet 4 in (13.21 m)
Airco DH.4 Height: 11 ft (3.35 m)
Airco DH.4 Wing area: 434 ft² (40 m²)
Airco DH.4 Empty weight: 2,387 lb (1,085 kg)
Airco DH.4 Max takeoff weight: 3,472 lb (1,578 kg)
Airco DH.4 Engine: Single 375 hp (289 kW) Rolls-Royce Eagle VII inline liquid cooled V12 piston engine
Airco DH.4 Maximum speed: 143 mph (230 km/h)
Airco DH.4 Range: 470 mi (770 km)
Airco DH.4 Service ceiling: 22,000 ft (6,700 m)

Airco DH.4 Biplane Armament:

Guns:
Single forward-firing Vickers .303 machine gun with interrupter gear and a Lewis gun mounted on a Scarff ring around the rear cockpit.

Bombs:
460 lb (210 kg)