Design and Development
The DH.9A was planned as an improved version of the existing Airco DH.9. The DH.9 was a disappointment owing to its underpowered and unreliable engines, and the DH.9A was planned to use much more powerful engines to resolve this. As the Rolls-Royce Eagle engine used in the successful DH.4 was unavailable in sufficient quantities, the new 400 hp (298 kW) American Liberty engine was chosen instead.
As Airco was busy developing the Airco DH.10 twin-engined bomber, detailed design was carried out by Westland Aircraft. The DH.9 was fitted with new, longer span wings, and a strengthened fuselage structure.
The first prototype flew in March 1918, powered by a Rolls-Royce Eagle as no Liberty engines were yet available. The prototype proved successful, with the first Liberty-engined DH.9A flying on 19 April 1918, and deliveries to the Royal Air Force starting in June. By the end of the war, a total of 2,250 DH.9As had been ordered, with 885 having built by the end of the year. As it was decided that the DH.9A would be a standard type in the postwar RAF, the majority of outstanding orders were fulfilled, with 1,730 being built under the wartime contracts before production ceased in 1919.
While the existing aircraft were subject to a programme of refurbishment, a number of small contracts were placed for new production of DH.9As in 1925–26. These contracts resulted in a further 268 DH.9As being built. The new production and refurbished aircraft included batches of dual control trainers and six experimental aircraft powered by 465 hp Napier Lion engines, which reached a maximum speed of 144 mph.
The Soviet Union built large numbers of an unlicenced copy of the DH.9A, the R-1. After the production of 20 DH.4 copies, followed by about 200 copies of the DH.9 powered by the Mercedes D.IV engine (also designated the R-1) and a further 130 powered by the Siddeley Puma (designated R-2), a copy of the DH.9A, powered by the M-5 engine, a Soviet copy of the DH.9A's Liberty entered production in 1924.
Read more about this topic: Airco DH.9A
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