Airco DH . 5 The Airco DH . 5 was a British First World War single - seat fighter aircraft designed specifically to replace the obsolete Airco DH . 2 . It was one of the first British fighter designs to include the improved Constantinesco interrupter gear , which allowed a forward - firing machine gun to fire through the propeller faster and more reliably than the older mechanical gears . It was also one of the earliest biplanes to feature a marked " back - stagger " of its wings . The DH . 5 was inferior to other fighters already in production , and proved unpopular and unsatisfactory in service . It was replaced as soon as supplies of the S . E . 5a permitted . Design and development . Captain Geoffrey de Havilland designed the Airco DH . 5 to combine the superior performance of a tractor biplane with the excellent forward visibility of a " pusher " type . The construction was that of a conventional tractor biplane of the time , but the main planes were given 27 inches of backward stagger , so that the lower wing was positioned forward of the upper wing . In the prototype armament installation , the forward - firing . 303 in ( 7 . 7 mm ) Vickers machine gun , equipped with the new Constantinesco interrupter gear , was either fixed to fire upward at an angle or possibly mounted so that its elevation could be adjusted in flight ; in the production installation the gun was given a more conventional fixed mounting on top of the cowl , offset to the left , to fire in the line of flight . As the pilot was seated forward of the centre of gravity , the main fuel tank was necessarily behind the cockpit , below the oil tank . An auxiliary gravity fuel tank was fitted over the top main plane , offset to the right . By the time the prototypes of the DH . 5 underwent service trials in December 1916 in France , superior types such as the Sopwith Camel and the Royal Aircraft Factory S . E . 5 were not far behind . In fact , the new fighter was inferior in most respects to the earlier Sopwith Pup . The provision of a single machine gun at a time when most fighters carried two also meant the aircraft was somewhat under - armed for operations in 1917 . Nonetheless , the DH . 5 was ordered in quantity from four manufacturers : Airco ( 200 ) , British Caudron ( 50 ) , Darracq ( 200 ) and March , Jones & Cribb ( 100 ) . Operational history . In service the type proved unpopular – its unconventional appearance led to rumours ( largely unfounded ) of handling difficulties . What was true was that its performance rapidly dropped off at altitudes over 10 , 000 ft ( 3 , 000 m ) , and that while it was very manoeverable , it tended to lose altitude quickly in combat . The unusual position of the upper main plane resulted in an unfortunate " blind spot " above and to the rear ( the very direction from which a single seater was generally attacked ) . On the other hand , the robustness of its construction , its good performance at low altitude , and the pilot ' s good forward field of view made the aircraft a useful ground attack aircraft . In this role , the type served with distinction in the Battle of Cambrai . The DH . 5 has the historical distinction of having formed the initial equipment of No . 2 Squadron of the Australian Flying Corps - the first Australian fighter squadron . It did not prove satisfactory , serving mainly in the ground attack role until December 1917 , when it was replaced by the S . E . 5a . By this time , the withdrawal of the type from the Western Front was already almost complete - the last DH . 5 squadron receiving the S . E . 5a in January 1918 . DH . 5s issued to training units proved unpopular and the type soon vanished from RFC service . No original aircraft has survived , but an airworthy full - scale replica , built in the United States by John Shiveley , is on display in the Aviation Heritage Centre , Omaka Aerodrome , New Zealand .