Westland Wapiti The Westland Wapiti was a British two - seat general purpose military single - engined biplane of the 1920s . It was designed and built by Westland Aircraft Works to replace the Airco DH . 9A in Royal Air Force service . First flying in 1927 , the Wapiti entered service with the RAF in 1928 , and remained in production until 1932 , a total of 565 being built . It equipped twenty squadrons of the RAF , both overseas ( particularly in India and Iraq ) and at home , remaining in RAF service until 1940 , also being used by the Air Forces of Australia , Canada , South Africa and India . It also formed the basis for the Westland Wallace which partly replaced the Wapiti in RAF use . Design and development . In 1927 , the British Air Ministry issued Specification 26 / 27 for a replacement of the elderly Airco DH . 9A , designed during the First World War which still equipped the Royal Air Force ' s General Purpose squadrons . To save time and money , the specification called for the use of a high proportion of DH . 9A components , ( as the RAF still held large stores of DH . 9A spares ) , while it encouraged the use of an all - metal structure . A large number of types were tendered to meet this requirement from most of the major British aircraft manufacturers , including Westland , who submitted the design that later became known as the Wapiti . Westland had an advantage in that it had carried out the detailed design work for the DH . 9A , and was already a major contractor for the DH . 9A . The Wapiti was a conventional single - engined equal span two - bay biplane with slight stagger . It had tandem open cockpits and a fixed main undercarriage plus tail - skid . The forward fuselage was of metal tube structure with aluminium and fabric covering , while the rear fuselage was of fabric covered wooden construction . The wings and tail were standard wooden DH . 9A components , although later models replaced the wooden parts with an all - metal structure . The Wapiti was powered by a single Bristol Jupiter radial engine , and its crew of two were armed with a forward firing Vickers machine gun and a Lewis gun for the observer , while it could carry up to 580 lb ( 264 kg ) of bombs under the wings and fuselage . It was also fitted with radio and photographic cameras , and like the DH . 9A before it , could carry a spare wheel for operations in adverse terrain . The prototype first flew on 7 March 1927 . Initial tests showed poor control , and the prototype was modified with a much larger tail and horn - balanced ailerons , solving these problems . ( It was later discovered that a 2 foot ( 0 . 61 m ) fuselage section had been omitted from the prototype - as handling was now acceptable , it was not re - instated . ) The Wapiti performed well during RAF trials , while using significant amounts of DH . 9A components , and was declared the winner of the competition , an initial contract for 25 aircraft being placed in October 1927 . After initial production , the wooden fuselage , tail and wings were replaced by metal structures in the Wapiti II and IIA , and the original long fuselage was eventually re - instated in the Wapiti V and later versions . In 1930 , Westland produced an updated version of the Wapiti , the Wapiti VII , which differed so much that it was renamed the Westland Wallace . Operational history . The type entered service with No . 84 Squadron RAF in Iraq in June 1928 . It was heavily used in Iraq and India in the Army Co - operation role , acting also sometimes as a bomber or reconnaissance aircraft . Wapitis of No . 20 squadron escorted Victoria troop carriers in the evacuation of Kabul ( the Kabul Airlift ) in December 1928 . It was still in service in India until 1939 . In Britain , Wapitis served with the Auxiliary Air Force from 1929 to 1937 . It was also flown by Australia and Canada , where it saw service at the start of the Second World War . The prototype Wapiti V , registered " G - AAWA " , was used for demonstration flights in Argentina and Uruguay on floats , powered by a 550 hp Armstrong Siddeley Panther IIA engine . It was later modified as the Bristol Pegasus powered Westland PV - 6 or Wapiti VII , re - registered " G - ACBR " ( also known as the Houston - Wallace after the patron Lucy , Lady Houston ) , for an attempt to fly over Mount Everest . Flown by Flt Lt David F . McIntyre and accompanied by a Westland PV - 3 the two aircraft became the first to fly over Mount Everest on 3 April 1933 . The PV - 6 was later designated the Wallace Mk I , bearing serial " K3488 " which introduced a number of improvements . A total of 68 Wapitis were converted to Wallace Mk I standard . ( in India ) ( in Iraq ) ( in the United Kingdom ) Variants . All built by Westland at Yeovil Survivors . A Westland Wapiti ( S . No . K - 183 ) survives as the last surviving aircraft of the type at the Indian Air Force Museum , Palam , Delhi . The fuselage and lower wing of another ( S . No . K - 181 ) reportedly survived at the museum ' s storage facility until it was confirmed that only K - 181 ' s lower wing survives in a ruinous condition at the storage facility in June 2012 .