Armstrong Whitworth Whitley The Armstrong Whitworth A . W . 38 Whitley was one of three British twin - engine , front line medium bomber types in service with the Royal Air Force at the outbreak of the Second World War ( the others were the Vickers Wellington and the Handley Page Hampden ) . It took part in the first RAF bombing raid on German territory , and remained an integral part of the early British bomber offensive until the introduction of four - engined " heavies " . Its front line service included maritime reconnaissance with Coastal Command , while also being employed in the second line roles of glider - tug , trainer and transport aircraft . The aircraft was named after Whitley , a suburb of Coventry , home of one of Armstrong Whitworth ' s plants . Design and development . The Whitley was designed by John Lloyd , the Chief Designer of Armstrong Whitworth Aircraft to meet Air Ministry Specification B . 3 / 34 issued in 1934 for a heavy night bomber . The AW . 38 design was a development of the Armstrong Whitworth AW . 23 bomber - transport design that had lost to the Bristol Bombay for specification C . 26 / 31 partly due to its Armstrong Siddeley Tiger engines . The Whitley carried a crew of five and was the first aircraft serving with the RAF to have a ( semi ‑ ) monocoque fuselage , using a slab - sided structure which eased production . As Lloyd was unfamiliar with the use of flaps on a large heavy monoplane , they were initially omitted . To compensate , the mid - set wings were set at a high angle of incidence ( 8 . 5° ) to confer good takeoff and landing performance . Although flaps were included late in the design stage , the wing remained unaltered . As a result , the Whitley flew with a pronounced nose - down attitude , resulting in considerable drag . This " nose down " attitude was also seen in the design of the Armstrong Whitworth Ensign pre - war airliner . The first prototype Whitley Mk I ( " K4586 " ) flew from Baginton airfield on 17 March 1936 , piloted by Armstrong Whitworth ' s Chief Test Pilot Alan Campbell - Orde and was powered by two Armstrong Siddeley Tiger IX radial engines . The second prototype was powered by more powerful Tiger XI engines . Owing to the urgent need to replace biplane heavy bombers in service with the RAF , an order for 80 aircraft had been placed in 1935 , " off the drawing board " . These had medium - supercharged engines and manually operated drum magazine single machine guns fore and aft . After the first 34 aircraft had been built , the engines were replaced with more reliable two - stage supercharged Tiger VIIIs , resulting in the Whitley Mk II , that completed the initial order . One Whitley Mk II , " K7243 " , was used as a test bed for the 1 , 200 hp 21 - cylinder radial Armstrong Siddeley Deerhound engine , first flying with the Deerhound on 6 January 1939 . The replacement of the manually operated nose turret with a powered Nash & Thomson turret and a powered retractable two - gun ventral " dustbin " turret resulted in the Whitley Mk III . The turret was hydraulically powered but it was hard to operate and added considerable drag . While the Tiger VIIIs used in the Whitley Mks II and III were more reliable than those used in early aircraft , the Whitley was re - engined with Rolls - Royce Merlin engines in 1938 giving rise to the Whitley Mk IV . These demonstrated greatly improved performance and the decision was made to introduce a series of other minor upgrades to produce the Whitley Mk V . The modifications included modified fins , leading edge de - icing , manually operated tail and retractable ventral turrets replaced with a Nash & Thompson powered turret equipped with four . 303 in ( 7 . 7 mm ) Browning machine guns , tail fuselage extended by 15 in ( 381 mm ) to improve the field of fire . The Mk V would be the most numerous version of the Whitley , with 1 , 466 built until production ended in June 1943 . Early marks of the Whitley had bomb bay doors - the eight bays were in fuselage compartments and wing cells - that were kept closed by bungee cords and opened by the weight of the released bombs falling on them . Even the tiny random delay in time that it took for the doors to open led to highly inaccurate bombing . The Mk . III introduced hydraulically actuated doors which greatly improved bombing accuracy . To aim bombs , the bomb aimer opened a hatch in the nose of the aircraft which extended the bombsight out of the fuselage but to everyone ' s comfort , the Mk IV replaced this hatch with a slightly extended transparency . The bomb aimer position was in the nose with a gun turret above . The pilot and second pilot / navigator were sat side by side in the pilot cockpit . The navigator rotated so they could use the chart table behind . Behind the pilots was the wireless operator . The fuselage aft of the wireless operator was divided horizontally by the bomb bay . Aft of the bomb bay was the main entrance and aft of that the rear turret . Operational history . The Whitley first entered service with No . 10 Squadron in March 1937 , replacing Handley Page Heyford biplanes . By the outbreak of the Second World War , seven squadrons were operational , the majority flying Whitley IIIs or IVs as the Whitley V had only just been introduced . With the Handley Page Hampden and the Vickers Wellington , Whitleys bore the brunt of the early fighting and saw action on the first night of the war when they dropped leaflets over Germany . Amongst the many aircrew who flew the Whitley in operations over Germany was Leonard Cheshire who spent most of his first three years at war flying Whitleys . Unlike the Hampden and Wellington – which met specification B . 9 / 32 for a day bomber – the Whitley was always intended for night operations and so did not share the early heavy losses received in daylight raids on German shipping early in the war . With Hampdens , the Whitley made the first bombing raid on German soil on the night of 19 / 20 March 1940 , attacking the Hornum seaplane base on the Island of Sylt . Whitleys also carried out the first RAF raid on Italy on 11 / 12 June 1940 . As the oldest of the three bombers , the Whitley was obsolete by the start of the war , yet over 1 , 000 more were produced before a suitable replacement was found . A particular problem with the twin - engine aircraft was that it could not maintain altitude on one engine . With Bomber Command , Whitleys flew 8 , 996 operations , dropped 9 , 845 tons ( 8 , 931 tonnes ) of bombs with 269 aircraft lost in action . The Whitley was retired from front line service in late 1942 but it continued to operate as a transport for troops and freight , as well as for paratroop training and towing glider s . No . 100 Group RAF used Whitleys to carry airborne radar and electronic counter - measures . The British Overseas Airways Corporation operated 15 Whitley Mk Vs converted into freighters in 1942 . Running night supply flights from Gibraltar to Malta , they took seven hours to reach the island , often landing during air attacks . They used large quantities of fuel for a small payload and were replaced in August 1942 by the Lockheed Hudson , with the 14 survivors being returned to the Royal Air Force . The long - range Coastal Command Mk VII variants were among the last to see front line service , with the first kill attributed to them being the sinking of the German U - boat " U - 751 " , on 17 July 1942 in combination with a Lancaster heavy bomber . Having evaluated the Whitley in 1942 , the Fleet Air Arm operated a number of modified ex - RAF Mk VIIs from 1944 – 46 to train aircrew in Merlin engine management and fuel transfer procedures . Variants . Following the two prototypes ( " K4586 " and " K4587 " ) , at the outbreak of the war the RAF had 207 Whitleys in service ranging from Mk I to Mk IV types , with improved versions following : Survivors . Of the 1 , 814 Whitleys produced , there are no surviving complete aircraft in existence ; however , The Whitley Project are rebuilding an example from salvaged remains and a fuselage section is displayed at the Midland Air Museum ( MAM ) whose site is adjacent to the airfield from where the Whitley ' s maiden flight took place .