Airco DH.9

The Airco DH.9, also known after 1920 as the de Havilland DH.9, was a British single-engined biplane bomber developed and used in the First World War. It was a development of Airco's successful DH.4 and shared many of its components, mated to an all-new fuselage and the 230 hp Beardmore Halford Pullinger engine, which promised better performance. The type was ordered in very large numbers for the Royal Flying Corps, and the prototype, a converted DH.4, made its first flight from Hendon in July 1917. In service its performance proved unsatisfactory: the engine was unreliable and gave less power than expected, so the DH.9 performed worse than the aircraft it was meant to replace, and the shortfall was blamed for heavy losses over the Western Front. The redesigned DH.9A followed, and the DH.9 was withdrawn from RAF service in 1920 after production continued into 1919.