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Armstrong Whitworth Whitley
Design and Development

The Armstrong Whitworth Whitley was concieved in response to Air Ministry specification B.3/34 which called for heavy night bomber. The Whitley was designed by a team headed by Armstrong Whitworth Aircrafts chief designer, John Lloyd. Developed from the design of the AW.23 bomber-transport design that lost the competition for Air Ministry Specification C.26/31, won by the Bristol Bombay.

Carrying a crew of five, the Whitley was the first aircraft accepted by the RAF to have a monocoque fuselage. The project, now given the company code AW.38, was designed with a slab-sided structure and the mid-mounted wings were set at a high angle of incidence (8.5°) to provide improved take-off and landing performance. Initially flaps were omitted by later on the design was modified to include them. The design and placement of the wings gave the AW.38 a distinct "nose-down" attitude when flying straight and level, unfortunaely resulting in considerable drag.

Eventually the AW.38 acquired the name Whitley, being named after a suburb of Coventry where the production facilities were located.

The first aircraft of this design to fly was the Whitley Mk. I (K4586), which took to the air from Baginton airfield on March 17, 1936. Piloted by Alan Campbell-Orde, Armstrong Whitworth's chief test pilot, K4586 was powered by two Armstrong Siddeley Tiger IX radial engines providing 795hp each. The second prototype flew with Armstrong Siddeley Tiger XI radials.

In 1935, with war looming on the horizon, the RAF felt the urgent need to replace its fleet of aging biplane heavy bombers. Thus an order for 80 Whitley Mk. Is were ordered straight "off the drawing board" before the first prototype had flown. The first 34 aircraft were fitted with the Armstrong Siddeley Tiger IX engine. The next aircraft were fitted with the Tiger VIII, with a two-stage supercharger and were considered more reliable. These aircraft were designated as Whitley Mk IIs and 46 aircraft were built in this configuration, fulfilling the initial RAF order.

The addition of a retractable two gun ventral turret and the replacement of the manually operated nose turret with a powered turret in a Whitley II test aircraft, K7243, led to the Whitley Mk. III.

In 1938 the Whitley was fitted with Rolls-Royce Merlin engines, resulting in the Whitley Mk. IV. Additional modifications and minor upgrades led to the Whitley Mk. V. These modifications included leading edge de-icing equipment on the wings, modification of the tail, and replacing the manual tail turret and ventral turret with powered models with four .303 Browning machine guns. The tail was also lengthened to improve the field of fire for the tail gunner. The Whiley Mk. V was the most numerous version of the Whitley with 1,466 being built. Production ended in June 1943.


Armstrong Whitworth factory showing Whitley Mk.V bombers being constructed, 1941.

Early marks of the Whitley had bomb bay doors 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 performance. The Mk.III introduced hydraulically actuated doors which greatly improved bombing accuracy. To aim bombs, the bombardier 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.

Sources:
Gunston, Bill - The Encyclodepia of the Worlds Combat aircraft, 1976, Chartwell Books, Inc., New York
Green, William - War Planes Of The Second World War - Fighters - Vol. 2, 1961, Hanover House, New York
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