Airco DH . 9 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 . A single - engined biplane , it was a development of Airco ' s earlier , highly successful DH . 4 and was ordered in very large numbers for Britain ' s Royal Flying Corps and Royal Air Force . Its engine was unreliable , and failed to provide the expected power , giving the DH . 9 poorer performance than the aircraft it was meant to replace , and resulting in heavy losses , particularly over the Western Front . The subsequently - developed DH . 9A had a more powerful and reliable American Liberty L - 12 engine . Design and 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 to the gunner / observer and away from the engine and fuel tank . The other major change from the DH . 4 was the choice of the promising new BHP / Galloway " Adriatic " engine , which was predicted to produce 300 hp ( 224 kW ) 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 bomber s . Based on the performance estimates for the DH . 9 ( which were expected to surpass those of the DH . 4 ) , 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 its expected power , with the engine being de - rated to 230 hp ( 186 kW ) 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 . 9 where the DH . 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 ( 321 kW ) Napier Lion engine , these were generally unsuccessful ( although the Lion engined aircraft did set a World Altitude Record of 30 , 500 ft ( 13 , 900 m ) on 2 January 1919 ) and it required redesign into the DH . 9A to transform the aircraft . Operational history . The first deliveries were made in November 1917 to 108 Squadron RFC and it first went into combat over France in March 1918 with 6 Squadron , and by July 1918 nine squadrons operational over the Western Front were using the type . The DH . 9 ' s performance in action over the Western Front was a disaster , with heavy losses incurred , both due to its poor performance and to engine failures , despite the prior de - rating of its engine . 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 . Nevertheless , on 23 August 1918 a DH9 flown by Lieutenant Arthur Rowe Spurling of 49 Squadron , with his observer , Sergeant Frank Bell , single - handedly attacked thirty Fokker D . VII fighters , downing five of them . Captain John Stevenson Stubbs managed 11 aerial victories in a DH9 , including the highly unusual feat of balloon busting with one . The DH . 9 was also more successful against the Turkish forces in the Middle East , where they faced less opposition , and it was used extensively for coastal patrols , to try to deter the operations of U - boats . Following the end of the First World War , DH . 9s operated by 47 Squadron and 221 Squadron were sent to southern Russia in 1919 in support of the White Russian Army of General Denikin during the Russian Civil War . The last combat use by the RAF was in support of the final campaign against Mohammed Abdullah Hassan ( known by the British as the " Mad Mullah " ) in Somalia during January — February 1920 . Surprisingly , production was allowed to continue after the end of the war into 1919 , with the DH . 9 finally going out of service with the RAF in 1920 . Following the end of the First World War , large number of surplus DH . 9s became available at low prices and the type was widely exported ( including aircraft donated to Commonwealth nations as part of the Imperial Gift programme . The South African Air Force received 48 DH . 9s , and used them extensively , using them against the Rand Revolt in 1922 . Several South African aircraft were re - engined with Bristol Jupiter radial engines as the M ' pala , serving until 1937 . Civilian 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 capability and were cheap . Early air services between London , Paris and Amsterdam were operated by DH . 9s owned by Aircraft Transport and Travel . A number of different conversions for civil use were carried out , both by Airco and its successor the de Havilland Aircraft Company and by other companies , such as the Aircraft Disposal Company . Some radial powered DH . 9Js continued in use until 1936 . ( Part of Imperial Gift ) Survivors . Of the thousands of DH . 9s built , only a few have survived to be preserved . " F1258 " is displayed at the " Musée de l ' Air et de l ' Espace " in Paris , with a second DH . 9 being preserved at the South African National Museum of Military History , while " G - EAQM " , the first single - engined aircraft to fly from the United Kingdom to Australia is preserved in the Australian War Memorial at Canberra . The remains of three DH . 9s were discovered in India in 2000 , one of which is displayed at the Imperial War Museum Duxford , and another in the process of being restored to flying condition .