Designed to Air Ministry Specification B. 3/34, which was circulated in July 1934, the Armstrong Whitworth A. W. 38 Whitley was the most extensively built of the company’s designs, production reaching a total of 1,814 aircraft. It also marked a departure from Armstrong Whitworth’s traditional steel-tube construction, the Whitley’s fuselage being a light alloy monocoque structure.
Production was authorised while the aircraft was still in the design stage, an order for 80 aircraft being placed in August 1935. Alan Campbell-Orde flew the first prototype at Whitley Abbey on 17 March 1936, the machine’s two Armstrong Siddeley Tiger X engines turning the then-new three-blade, variable-pitch de Havilland propellers. A second prototype built to Specification B.21/35 had the more powerful Tiger XI engines and was flown by Charles Turner Hughes on 24 February 1937.
Trials at the Aircraft and Armament Experimental Establishment at Martlesham Heath were undertaken in the autumn of 1936, and the first production Whitley Mk Is were delivered early in 1937, including the second aircraft which was flown to RAF Dishforth on 9 March for No. 10 Squadron. Thirty-four Mk Is were built before the Mk II was introduced. This mark had Tiger VIII engines with two-speed superchargers, the first fitted to an RAF aircraft; 46 Whitley Mk IIs completed the initial order for 80.
Mk I and Mk II Whitleys had Armstrong Whitworth manually-operated nose and tail turrets, each with a 0.303-in (7.7-mm) Vickers machine-gun, but in the Mk III the nose turret was replaced by a power-operated Nash and Thompson turret, and a retractable ventral turret with two 0.303-in Brownings was added. The 80 Whitley IIIs also had modified bomb bays to accommodate larger bombs.
By far the most numerous of the Whitley variants were those with Rolls-Royce engines. A Whitley I was fitted with Merlin IIs and test-flown at Hucknall on 11 February 1938, although engine failure prematurely concluded the second flight. The programme was quickly resumed, however, and during April and May the aircraft carried out trials at Martlesham Heath.
Merlin IVs of 1,030 hp (768 kW) were installed in production Whitley IVs, the first of which flew on 5 April 1939. Other changes incorporated in this version included a power-operated Nash and Thompson tail turret with four 0.303-in Browning guns, a transparent panel was added in the lower nose to improve the view for the bomb-aimer, and two additional wing tanks were fitted to bring total capacity to 705 Imperial gallons (3205 litres). Production totalled 33, together with seven Mk IVAs which had 1,145-hp 854-kW) Merlin X engines.
The same engines were retained for the Whitley V, which incorporated a number of improvements. The most noticeable of these were modified fins with straight leading-edges and an extension of 1 ft 3 in (0.38 m) to the rear fuselage to provide a wider field of fire for the rear gunner. Rubber de-icer boots were fitted to the wing leading-edges, and fuel capacity was increased to 837 Imperial gallons (3805 litres), or 969 Imperial gallons (4405 litres) if extra tanks were carried in the bomb bay. Production totalled 1,466 aircraft.
The Whitley VI was a projected version with Pratt & Whitney engines, .studied as an insurance against short supply of Merlins. It was not built , however, and the ultimate production Whitley was the Mk VII which was essentially a Mk V with auxiliary fuel tanks in the bomb bay and in the rear fuselage to bring the total capacity to 1,100 Imperial gallons (5001 litres), increasing the range to 2,300 miles (3701 km for maritime patrol duties. Externally the Mk VIIs could be distinguished by the dorsal radar aerials of the ASV Mk II air-to-surface radar. Production reached 146, and some Mk Vs were converted to the later standard.
As noted above. No.10 Squadron at RAF Dishforth was the first to equip with the Whitley, which replaced the Handley Page Heyford in March 1937. Nos. 51 and 58 Squadrons at RAF Leconfield soon followed and, during the night of 3 September 1939, 10 Whitley IIIs from these two squadrons flew a leaflet raid over Bremen, Hamburg and the Ruhr. Just under a month later, during the night of 1 October, No.10 Squadron flew a similar mission over Berlin. The first bombs were dropped on Berlin during the night of 25 August 1940, the attacking squadrons including Nos. 51 and 78 with Whitleys. To mark the entry of the Italians into the war, 36 Whitleys drawn from Nos. 10, 51, 58, 77 and 102 Squadrons were tasked to raid Genoa and Turin during the night of 11 June 1940, although only 13 actually reached their targets, weather and engine troubles taking their toll.
The Whitley was retired from Bomber Command in April 1942, the last operation being flown against Ostend during the night of 29 April, although some aircraft from operational training units were flown in the ‘1,000 Bomber’ raid on Cologne on the night of 30 May 1942.
Coastal Command’s association with the Whitley began in September 1939 when No. 58 Squadron was transferred to Boscombe Down to operate antisubmarine patrols over the English Channel. This lasted until February 1940, when the unit returned to Bomber Command, but during 1942 it took up patrol duties once again, flying over the Western Approaches from St Eval and Stornoway. Other units similarly occupied at that time included Nos. 51 and 77 Squadrons, the latter operating in the Bay of Biscay area.
Mk V Whitleys replaced the Avro Ansons of No. 502 Squadron at RAF Aldergrove in the autumn of 1940 and a second Coastal Command Whitley unit. No. 612 Squadron, formed in May 1941. The Mk Vs were replaced by the ASV Mk II-equipped Whitley VII, and an aircraft of No. 502 Squadron sank the type’s first German submarine when it attacked U-205 in the Bay of Biscay on 30 November 1941.
Whitleys were also used at No. 1 Parachute Training School at Ringway, Manchester, and were adapted for use as glider tugs, becoming attached to No. 21 Glider Conversion Unit at Brize Norton for the training of tug pilots. The paratroop raid on the German radar site at Bruneval used Whitleys of No. 51 Squadron, and the aircraft of ‘special duty’ units at RAF Tempsford (Nos. 138 and 161 Squadrons) flew numerous sorties, dropping agents into occupied territory and supplying Resistance groups with arms and equipment. Fifteen Whitley Vs were handed over to BOAC in May 1942 and, stripped of armament, but with additional fuel tanks in the bomb bays, flew regularly from Gibraltar to Malta carrying supplies for the beleaguered island.
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:
Powered by 795 hp (593 kW) Armstrong Siddeley Tiger IX air-cooled radial engines: 34 built
Powered by 920 hp (690 kW) two-stage supercharged Tiger VIII engines: 46 built
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
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
Powered by 1,145 hp (854 kW) Merlin X engines: seven built
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
Proposed Pratt & Whitney- or Merlin XX-powered version: none built
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
Specifications (Whitley Mk V)
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)
1 × .303 in (7.7 mm) Vickers K machine gun in nose turret
4 × .303 in Browning machine guns in tail turret
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