Airco DH.9A

The Airco DH.9A was a British single-engined light bomber designed and first used shortly before the end of the First World War. It was a development of the unsuccessful Airco DH.9 bomber, with a strengthened structure, and crucially, replacing the underpowered and unreliable Siddeley Puma engine of the DH.9 with the American Liberty engine.

Colloquially known as the "Ninak" (from the phonetic alphabet treatment of designation "nine-A"), it served on in large numbers for the Royal Air Force following the end of the war, both at home and overseas, where it was used for colonial policing in the Middle East, finally being retired in 1931. Over 2,400 examples of an unlicensed version, the Polikarpov R-1 was also built in the Soviet Union, the type serving as the standard Soviet light bomber and reconnaissance aircraft through the 1920s.

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.

U.S. version and pressurised flights
The United States also planned to adopt the DH.9A as a replacement for the DH.4. Development work on the aircraft commenced at McCook Field in Dayton, Ohio. Modifications included a new fuel system with increased fuel capacity, revised wings and tail surfaces, and replacement of the Vickers machine gun on the port side of the British built aircraft with a Browning machine gun on the starboard side. Plans called for the Curtiss Aeroplane and Motor Corporation of Buffalo, New York to build 4,000 modified aircraft, designated U.S.D-9A. This order was cancelled with the end of the war and only nine aircraft were built by McCook Field and by the Dayton-Wright Company. One McCook aircraft was highly modified with the addition of a completely enclosed, pressurised cockpit. In 1921, test pilot Lt. Harold R. Harris made the world's first high-altitude flight in a pressurised aircraft in the USD-9A at McCook Field in Dayton, Ohio.

First World War
The DH.9A entered service in July 1918 with No. 110 Squadron RAF, moving to France on 31 August 1918 to serve with the RAF's Independent Air Force on strategic bombing missions. Its first mission was against a German airfield on 14 September 1918. A further three squadrons commenced operations over the Western Front before the Armistice, with 99 Squadron (also serving with the Independent Air Force) replacing DH.9s, while 18 Squadron and 216 Squadron replaced DH.4s. Despite the superior performance of the DH.9A over the DH.9, the DH.9A squadrons suffered high losses during their long range bombing missions over Germany. Other squadrons flew coastal patrols from Great Yarmouth before the end of the year.

The United States Marine Corps also adopted the DH.9A, its Northern Bombing group receiving at least 53, operations starting in September 1918.

Interwar RAF service
While the squadrons in service at the end of the First World War quickly disbanded or re-equipped in the postwar dis-armament, the DH.9A continued in service as the RAF's standard light bomber, with a total of 24 squadrons being equipped between 1920 and 1931, both at home and abroad.

The first post war operations were in southern Russia in 1919, in support of the "White Army" against the Bolsheviks in the Russian Civil War. In September 1919, the RAF personnel were ordered to return home, leaving their aircraft behind. A squadron of DH.9As was deployed to Turkey in response to the Chanak Crisis in 1922, but did not engage in combat.

The DH.9A was one of the key weapons used by Britain to manage the territories that were in its control following the collapse of the Ottoman Empire at the end of the Great War. Five squadrons of DH.9As served in the Middle East, carrying out occasional bombing raids against rebelling tribesmen and villages. A larger radiator was fitted to cope with the high temperatures, while additional water containers and spares (including spare wheels lashed to the fuselage) were carried in case the aircraft were forced down in the desert, the DH.9A's struggling under ever heavier loads. Despite this it served successfully, with the Liberty engine being picked out for particular praise for its reliability ("as good as any Rolls Royce") in such harsh conditions. Some DH.9A aircraft were also transported to India to supplement the British Indian Army.

At home, the DH.9A continued on in regular RAF service until 1930, also forming the initial equipment of the Royal Auxiliary Air Force (RAuxAF).

Soviet service
The R-1 was heavily used by the Soviet Air Forces through the 1920s as its standard light bomber and reconnaissance aircraft. The Soviets deployed R-1s in support of the Chinese Kuomintang forces in the Northern Expedition against warlords in 1926-27 and against Chinese forces in clashes over control of the Chinese Eastern Railway in Manchuria in 1929. R-1s were also used in support of operations against Basmachi Rebels in central Asia.

Variants

 * Airco DH.9A: Original version.
 * de Havilland DH.9AJ: Single prototype with Bristol Jupiter engine.
 * de Havilland DH.9R: Racing aircraft with sesquiplane wing powered by Napier Lion engine - (one built).
 * Airco DH.15 Gazelle: Re-engined DH.9A with a BHP Atlantic inline engine, one conversion
 * Airco DH.16: Civil transport with widened fuselage seating four passengers in a glazed cabin behind the pilot, who sat in an open cabin, nine built. Rolls Royce Eagle or Napier Lion Engine.
 * de Havilland DH-49 - proposed modernised version with Eagle IX engine (not built)
 * Engineering Division USD-9A: United States built version, 9 built. One modified with a pressurised cockpit.
 * Engineering Division USD-9B: USD-9A fitted with more powerful Liberty engine and greater area wings.
 * Armstrong Whitworth Tadpole One prototype conversion for a naval three-seat spotter/reconnaissance aircraft.
 * Westland Walrus Production version of the Tadpole conversion with the Napier Lion III engine (36 built).
 * Polikarpov R-1 and R-2 Copy of DH.9A built in Soviet Union, originally at Duks Aircraft Works, supervised by Nikolai Nikolaevich Polikarpov. Early  aircraft were powered by Mercedes D.IV or Armstrong Siddeley Puma, but with most powered by an M-5 copy of the Liberty Engine.  Produced 1922–1932, with over 2,400 built.
 * Polikarpov R-1 BMW: This version of the R-1, was fitted a 240 hp (179 kW) BMW IVa engine, 20 built.
 * Polikarpov MR-1: Twin-float seaplane version, 124 built.
 * Polikarpov PM-2: Prototype floatplane fitted with metal floats.

Operators

 * 🇦🇫 Afghanistan
 * Afghan Air Force - Airco DH.9As and Polikarpov R-1s
 * Royal Australian Air Force: The RAAF received 28 DH.9As (RAAF serial A6-1 to A6-28). The aircraft were in service from 1920 to 1930.
 * No. 1 Squadron RAAF
 * No. 3 Squadron RAAF
 * No. 1 Flying Training School RAAF
 * 🇨🇦 Canada
 * Canadian Air Force (1918-1920)
 * Royal Canadian Air Force
 * 🇮🇷 Iran
 * Imperial Iranian Air Force
 * 🇱🇻 Latvia
 * Latvian Air Force
 * Mongolian People's Air Force : Polikarpov R-1s and R-2s
 * 🇨🇭 Switzerland
 * Swiss Air Force : One aircraft only.
 * Royal Air Force
 * No. 3 Squadron RAF
 * No. 8 Squadron RAF
 * No. 11 Squadron RAF
 * No. 14 Squadron RAF
 * No. 15 Squadron RAF
 * No. 18 Squadron RAF
 * No. 22 Squadron RAF
 * No. 24 Squadron RAF
 * No. 25 Squadron RAF
 * No. 30 Squadron RAF
 * No. 39 Squadron RAF
 * No. 45 Squadron RAF
 * No. 47 Squadron RAF
 * No. 55 Squadron RAF
 * No. 60 Squadron RAF
 * No. 84 Squadron RAF
 * No. 99 Squadron RAF
 * No. 100 Squadron RAF
 * No. 110 Squadron RAF
 * No. 205 Squadron RAF
 * No. 207 Squadron RAF
 * No. 207 Squadron RAF
 * No. 221 Squadron RAF
 * No. 273 Squadron RAF
 * No. 501 Squadron RAF
 * No. 600 Squadron RAF
 * No. 601 Squadron RAF
 * No. 602 Squadron RAF
 * No. 603 Squadron RAF
 * No. 604 Squadron RAF
 * No. 605 Squadron RAF
 * No. 603 Squadron RAF
 * No. 604 Squadron RAF
 * No. 605 Squadron RAF


 * United States Navy
 * United States Marine Corps
 * Soviet Air Force : Polikarpov R-1s and R-2s
 * Soviet Air Force : Polikarpov R-1s and R-2s
 * Soviet Air Force : Polikarpov R-1s and R-2s