Airco DH.9

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D.H.9

Airco D.H.9
Type	Bomber
Manufacturer	Airco
Designed by	Geoffrey de Havilland
Maiden flight	July 1917
Retired	1920
Primary users	Royal Air Force RNAS, RFC.
Number built	4091
Variants	Airco DH.9A Westland Walrus

The Airco DH.9 (from de Havilland 9) also known after 1920 as the de Havilland DH.9 was a British bomber used in the First World War. It was subsequently developed into the DH.9A with a more powerful engine.

1 Development
2 Operational Service
3 DH.9A
4 Civil Use
5 Variants
6 Operators
- 6.1 Military Operators
- 6.2 Civil Operators
7 Specifications (D.H.9 (Puma Engine))
8 References
9 External links
10 Related content

[edit] Development

The DH.9 was designed by de Havilland for the Aircraft Manufacturing Company in 1916 as a successor to the DH.4. It used the wings and tail unit of the DH.4 but had a new fuselage. This enabled the pilot to sit closer the gunner/observer and away from the engine and fuel tank. The other major change from the D.H.4 was the choice of the promising new Galloway-Adriatic (or BHP) engine, which was predicted to produce 300 hp and so give the new aircraft an adequate performance to match enemy fighters.

By this time, as a result of attacks by German bombers on London, the decision was made to almost double the size of the Royal Flying Corps, with most of the new squadrons planned to be equipped with bombers. Based on the performance estimates for the DH.9, and the similarity to the DH.4, which meant that it would be easy to convert production over to the new aircraft, massive orders (4,630 aircraft) were placed.

The prototype (a converted DH.4) first flew at Hendon in July 1917. Unfortunately, the BHP engine proved unable to reliably deliver the power expected of it, with the engine being de-rated to 230 hp in order to improve reliability. This had a drastic effect on the aircraft's performance, especially at high altitude, with it being inferior to that of the DH.4 it was supposed to replace. This meant that the DH.9 would have to fight its way through enemy fighters, which could easily catch the DH.9s where the D.H.4 could avoid many of these attacks.

While attempts were made to provide the DH.9 with an adequate engine, with aircraft being fitted with the Siddeley Puma, a lightened and supposedly more powerful version of the BHP, with the Fiat A12 engine and with a 430 hp Napier Lion engine, these were generally unsuccessful and it required redesign into the DH.9A to transform the aircraft.

[edit] Operational Service

The first deliveries were made in November 1917 to 108 Squadron RFC, with several more squadrons being formed or converted to the D.H.9 over the next few months, and with nine squadrons operational over the Western Front by June 1918.

The D.H.9's performance in action over the Western font was a disaster, with heavy losses being incurred, both due to its low performance, and engine failures (despite the prior de-rating of its engine). For example, between May and November 1918, two squadrons on the Western Front (Nos. 99 and 104) lost 54 shot down, and another 94 written off in accidents. The DH.9 was however more successful against the Turkish forces in the Middle East, where they faced less heavy opposition, and was also used extensively for coastal patrols, to try and deter the operations of U-boats.

Surprisingly, production was allowed to continue after the end of the war into 1919, with the D.H.9 finally going out of service in 1920.

[edit] DH.9A

Main article: Airco DH.9A

Three DH.9A in formation.

The DH.9A (also referred to as the Nine-Ack) was designed for Airco by Westland Aircraft to take advantage of the American Liberty 12 400 hp (298 kW) engine. The DH.9A also featured larger wings than the DH.9.

The DH.9A was armed with a Vickers machine gun synchronized to fire through the propeller for the pilot, and either a single or double Lewis Gun for the observer.

[edit] Civil Use

Because of the large number of surplus DH.9s available after the war many were used by air transport companies. They provided a useful load carrying capablity and were cheap. Early air services between London, Paris and Amsterdam were operated by DH.9s owned by Aircraft Transport and Travel.

[edit] Variants

DH.9 - Revised version of the DH.4 with the pilot and observer/gunner placed closer together (3,024 production aircraft built with others built in Belgian and Spain.
DH.9A -

Main article: Airco DH.9A

Improved and re-engined version (2,300 built by 10 different British companies).

DH.9B - Conversions for civilian use as three-seaters (one pilot and two passengers)
DH.9C - Conversions for civilian use as four-seaters (one pilot and three passengers)
DH.9J - Modernised and re-engined conversions using the 385-hp (287-kW) Armstrong Siddeley Jaguar III radial piston engine. Used by the De Havilland School of Flying.
DH.9J M'pala I - Re-engined conversions carried out by the South African Air Force. Powered by a 450-hp (336-kW) Bristol Jupiter VI radial piston engine.
M'pala II - Re-engined conversions carried out by the South African Air Force. Powered by a 480-hp (358-kW) Bristol Jupiter VIII radial piston engine.
Mantis - Re-engined conversions carried out by the South African Air Force. Powered by a 200-hp (149-kW) Wolseley Viper piston engine.