Hawker Horsley The Hawker Horsley was a British single - engined biplane bomber of the 1920s . It was the last all wooden aircraft built by Hawker Aircraft , and served as a medium day bomber and torpedo bomber with Britain ' s Royal Air Force between 1926 and 1935 , also serving with the Navies of Greece and Denmark . Design and development . The Horsley ( named after Sir Thomas Sopwith ' s home of Horsley Towers ) was originally designed to meet Air Ministry Specification 26 / 23 for a day bomber powered by a single Rolls - Royce Condor engine . While the specification called for any production aircraft to be of metal construction , Hawker proposed to build the prototype of wooden construction , gradually switching to a metal structure during production . This was acceptable to the Air Ministry , and an order for a single prototype was placed . The first prototype was flown in March 1925 , powered by a 650 hp ( 485 kW ) Condor III engine , and was delivered to the Aeroplane and Armament Experimental Establishment at Martlesham Heath on 4 May 1925 . Meanwhile , the Air Ministry revised its requirements , producing Specification 23 / 25 which increased the required payload from one to two 551 lb ( 250 kg ) bombs . At the same time , it also issued Specification 24 / 25 for a torpedo bomber , required to carry a 2 , 150 lb ( 975 kg ) torpedo . The Horsley ' s ability to cope with the increased loads required to meet these new specifications lead to the design being favoured by the RAF , with an initial order of forty aircraft , consisting of 10 wooden Mk Is and 30 Mk IIs of mixed metal and wood construction , being placed . Description . The Horsley was a large single - engined two - bay biplane . It had a crew of two , comprising a pilot and a gunner / bomb - aimer / radio operator , who had a . 303 in ( 7 . 7 mm ) Lewis gun mounted in a Scarff ring in the rear cockpit and a prone position for bomb aiming . The rear cockpit was also fitted with dual controls . The payload included two 551 lb ( 250 kg ) bombs , one 1 , 500 lb ( 680 kg ) bomb or a torpedo weighing 2 , 800 lb ( 1 , 270 kg ) . The structure was originally all wood , but before production was complete an all - metal structure was introduced , made in what became the famous Hawker system of metal construction . The three methods of construction were designated ; Horsley Mk I for the all wooden aircraft , Horsley Mk II for the mixed material , and ( unofficially ) Horsley III for the all - metal aircraft . Some aircraft were fitted with floats . Two aircraft , powered by Leopard II engines were sold to the Danish Government , but these aircraft were known as Hawker Dantorp and had a slightly different fuselage , accommodating a third crew member . The Danes also purchased a license to build a further 10 aircraft at the Danish Naval Workshops ( Orlogsvaerftet ) , but these were not built owing to a shortage of funds . While production aircraft were powered by the Condor IIIA , the Horsley was much used as a flying test - bed for other engines . Engines tested included the Napier Lion , Rolls - Royce Buzzard , Rolls - Royce Eagle , the Armstrong Siddeley Leopard radial engine , the Junkers Jumo diesel engine and early versions of the Rolls - Royce Merlin . Operational history . The first aircraft were delivered to No 100 ( Bomber ) Squadron of the Royal Air Force in September 1927 , with two more squadrons , No . 15 and No . 11 Squadron s receiving Horsleys by the end of the year , replacing the Fairey Fawn . The Horsleys proved greatly superior to the Fawn , carrying up to three times the bomb load over greater ranges and at higher speeds , while also being agile for their size , and proving popular with its pilots . In October 1928 , No . 36 Squadron formed at Donibristle , Fife , Scotland as a torpedo - bomber squadron . It was transferred to Singapore in 1930 , helping to suppress a rebellion in Burma as well as maintaining its torpedo bombing skills . 100 Squadron converted to the torpedo bombing role in 1930 to fill the gap in home based defences . The Horsley was chosen to attempt a non - stop flight to India , with a specially modified aircraft , carrying much more fuel and taking off at a weight of over 14 , 000 lb ( 6 , 350 kg ) took off from RAF Cranwell on 20 May 1927 , flown by Flight Lieutenant s Roderick Carr and L . E . M Gillmann . It ran out of fuel " en route " , however , ditching in the Persian Gulf near Bandar Abbas , Iran . Despite this it had covered a distance of 3 , 420 mi ( 5 , 506 km ) , which was sufficient to set a new world distance record , but was beaten in turn within a few hours by Charles Lindbergh , whose solo Atlantic flight between New York and Paris in the " Spirit of St . Louis " covered 3 , 590 mi ( 5 , 780 km ) . The Horsleys remained in service in the day - bombing role until 1934 , with 504 Squadron ' s Horsleys being replaced by Westland Wallace s in March 1934 . No 36 Squadron at Singapore retained the Horsely in the Torpedo bomber role until July 1935 . The last Horsley , a Merlin powered test bed flew its final flight at RAE Farborough on 7 March 1938 . A total of 124 Horsleys were built , including six aircraft for the Hellenic Naval Air Service and the two Dantorps built for Denmark .