Armstrong Whitworth Whitley
|National origin||United Kingdom|
|Manufacturer||Armstrong Whitworth Aircraft|
|First flight||17 March 1936|
|Primary user||Royal Air Force|
|Developed from||Armstrong Whitworth AW.23|
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.
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 795 hp (593 kW) 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 still in service with the RAF, an order for 80 aircraft had been placed in 1935, "off the drawing board", before the Whitley had flown. 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 by 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 with the Whitley. The majority were 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 gliders. 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.
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:
- Mk II
- Powered by 920 hp (690 kW) two-stage supercharged Tiger VIII engines: 46 built
- Mk III
- Powered by Tiger VIII engines, retractable "dustbin" ventral turret fitted aft of the wing root armed with two .303 in (7.7 mm) machine guns, hydraulically operated bomb bay doors and ability to carry larger bombs: 80 built
- Mk IV
- Powered by 1,030 hp (770 kW) Rolls-Royce Merlin IV inline liquid-cooled engines, increased fuel capacity, extended bomb-aimer's transparency, produced from 1938: 33 built
- Mk IVA
- Powered by 1,145 hp (854 kW) Merlin X engines: seven built
- Mk V
- The main wartime production version based on the Mk IV, 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. First flew in December 1938, production ceased in June 1943: 1,466 built
- Mk VI
- Proposed Pratt & Whitney- or Merlin XX-powered version: none built
- Mk VII
- Designed for service with Coastal Command and carried a sixth crew member, capable of longer-range flights (2,300 mi/3,700 km compared to the early version's 1,250 mi/2,011 km) having additional fuel tanks fitted in the bomb bay and fuselage, equipped with Air to Surface Vessel (ASV) radar for anti-shipping patrols with an additional four 'stickleback' dorsal radar masts and other antennae: 146 built
Military operators 
- No. 7 Squadron RAF between March 1938 and May 1939.
- No. 10 Squadron RAF between March 1937 and December 1941.
- No. 51 Squadron RAF between February 1938 and October 1942.
- No. 53 Squadron RAF between February 1943 and May 1943.
- No. 58 Squadron RAF between October 1937 and January 1943.
- No. 76 Squadron RAF between September 1939 and April 1940.
- No. 77 Squadron RAF between November 1938 and October 1942.
- No. 78 Squadron RAF between July 1937 and March 1942.
- No. 97 Squadron RAF between February 1939 and May 1940.
- No. 102 Squadron RAF between October 1938 and February 1942.
- No. 103 Squadron RAF between October 1940 and June 1942.
- No. 109 Squadron RAF operated only one aircraft (P5047).
- No. 115 Squadron RAF during 1938
- No. 138 Squadron RAF between August 1941 and October 1942.
- No. 161 Squadron RAF between February 1942 and December 1942.
- No. 166 Squadron RAF between July 1938 and April 1940.
- No. 295 Squadron RAF between August 1942 and November 1943.
- No. 296 Squadron RAF between June 1943 and March 1943.
- No. 297 Squadron RAF between February 1942 and February 1944.
- No. 298 Squadron RAF between August 1942 and October 1942.
- No. 299 Squadron RAF between November 1943 and January 1944.
- No. 502 Squadron RAF between October 1940 and February 1943.
- No. 612 Squadron RAF between November 1940 and June 1943.
- No. 619 Squadron RAF between April 1943 and January 1944.
- No. 1419 Flight RAF
- No. 1473 Flight RAF
- No. 1478 Flight RAF
- No. 1481 Flight RAF
- No. 1484 Flight RAF
- No. 1485 Flight RAF
- No. 1486 Flight RAF
Civil Operators 
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 located adjacent to the airfield from where the Whitley's maiden flight took place.
Specifications (Whitley Mk V) 
Data from The Whitley File
- Crew: 5
- Length: 70 ft 6 in (21.49 m)
- Wingspan: 84 ft (25.60 m)
- Height: 15 ft (4.57 m)
- Wing area: 1,137 ft² (106 m²)
- Empty weight: 19,300 lb (8,768 kg)
- Max. takeoff weight: 33,500 lb (15,196 kg)
- Powerplant: 2 × Rolls-Royce Merlin X liquid-cooled V12 engine, 1,145 hp (855 kW) each
- Maximum speed: 200 kn (230 mph, 370 km/h) at 16,400 ft (5,000 m)
- Range: 1,430 nmi (1,650 mi, 2,650 km)
- Ferry range: 2,100 nmi (2,400 mi, 3,900 km)
- Service ceiling: 26,000 ft (7,900 m)
- Rate of climb: 800 ft/min (4.1 m/s)
- Max. wing loading: 29.5 lb/ft² (143 kg/m²)
- Minimum power/mass: 0.684 hp/lb (112 W/kg)
- Bombs: Up to 7,000 lb (3,175 kg) of bombs in the fuselage and 14 individual cells in the wings, typically including
- 12 × 250 lb (113 kg) and
- 2 × 500 lb (227 kg) bombs
- Bombs as heavy as 2,000 lb (907 kg) could be carried
See also 
- Aircraft of comparable role, configuration and era
- Related lists
- Crosby 2007, pp. 48–49.
- Gunston 1995, p. ?.
- Swanborough 1997, p. 8.
- Roberts 1986, p. 8.
- Flight 21 October 1937, p. 402.
- Mondey 1994, p. 18.
- Thetford 1957, p. 27.
- Green and Swanborough Air Enthusiast 1979, p. 22.
- Moyes 1976, p. 327.
- Jackson 1973, p. 325.
- U-boat.net/ "U-206." uboat.net. Retrieved: 8 August 2010.
- Uboat.net/ "U-751." uboat.net. Retrieved: 8 August 2010.
- Roberts 1978, p. 62.
- Roberts 1978, pp. 58–59.
- Roberts 1986, p. 68.
- "A Modern Heavy Bomber". Flight, 21 October 1937, pp. 396–402.
- Cheshire, Leonard. Leonard Cheshire V.C. Bomber Pilot. St. Albans, Herts, UK: Mayflower, 1975 (reprint of 1943 edition). ISBN 0-583-12541-7.
- Crosby, Francis. The World Encyclopedia of Bombers. London: Anness Publishing, 2007. ISBN 1-84477-511-9.
- Donald, David and Jon Lake. Encyclopedia of World Military Aircraft. London: AIRtime Publishing, 1996. ISBN 1-880588-24-2.
- Green, William. Famous Bombers of the Second World War. London: Macdonald and Jane's, 1959, (third revised edition 1975). ISBN 0-356-08333-0.
- Green, William and Gordon Swanborough. "Armstrong Whitworth's Willing Whitley" Air Enthusiast. No. 9, February–May 1979. Bromley, Kent, UK., pp. 10–25.
- Green, William and Gordon Swanborough. WW2 Aircraft Fact Files: RAF Bombers, Part 1. London: Macdonald and Jane's, 1979. ISBN 0-354-01230-4.
- Gunston, Bill. Classic World War II Aircraft Cutaways. Botley, Oxfordshire, UK: Osprey Publishing, 1995. ISBN 1-85532-526-8.
- Jackson, A.J. British Civil Aircraft since 1919 (Volume 1). London: Putnam & Company Ltd., 1973. ISBN 0-370-10006-9.
- Mason, Francis K. The British Bomber since 1914. London: Putnam Aeronautical Books, 1994. ISBN 0-85177-861-5.
- Mondey, David. The Hamlyn Concise Guide to British Aircraft of World War II. London: Chancellor Press, 1994. ISBN 1-85152-668-4.
- Moyes, Philip J.R. The Armstrong Whitworth Whitley. Leatherhead, Surrey, UK: Profile Publications Ltd., 1967.
- Moyes, Philip J.R. Bomber Squadrons of the RAF and Their Aircraft. London: Macdonald and Jane's, 1964, revised edition 1976. ISBN 0-354-01027-1.
- Roberts, Nicholas. Aircraft Crash Log No.4: Armstrong Whitworth Whitley. Leeds, UK: N. Roberts, 1978.
- Roberts, R.N. The Whitley File. Tonbridge, Kent, UK: Air-Britain (Historians), 1986. ISBN 0-85130-127-4.
- Swanborough, Gordon. British Aircraft at War, 1939-1945. East Sussex, UK: HPC Publishing, 1997. ISBN 0-9531421-0-8.
- Thetford, Owen. Aircraft of the Royal Aircraft, 1918-57. London: Putnam & Company Ltd., 1957.
- Wixey, Ken. Armstrong Whitworth Whitley (Warpaint Series No. 21). Denbigh East, Bletchley, UK: Hall Park Books, 1999. OCLC 65202527
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