Armstrong Whitworth Whitley, part three

 

In spite of the reliability of the Tiger VIII engine, which powered the Mk.II and Mk.III variants, in 1938 the Whitley was tested with Rolls-Royce Merlin engines creating this way the Mk.IV variant. Three Mk.I served as the prototypes. These new engines greatly improved performance and some other changes were also carried out, like the replacement of the manually operated tail and retractable ventral turrets with a Nash & Thompson powered turret containing four 0.303 in (7.7 mm) Browning machine guns, the increase of fuel capacity, with two additional fuel tanks in the wings. On this variant and the Mk.IVA (a sub-variant featuring a more powerful version of the Merlin engine) a total of 40 machines were manufactured at Baginton in 1939.

For the production of the Mk.V, it was decided to introduce minor improvements. Among these there were the modification of the tail fins and rudder, the fitting of the leading edge de-icers, further fuel capability increases, a smaller D/F loop antenna housed in a streamlined fairing, and the extension of the rear fuselage by 15 in (381 mm) to improve the rear gunner's field of fire. The prototype flew for the first time on December 1938 and this variant was, by far, the most produced version of the Whitley with 1466 units being produced at Baginton from 1939 until June 1943 when production ended.

The Mk.VII was the last variant to be built. It was built to serve with the RAF Coastal Command and, therefore, it was equipped for maritime reconnaissance, rather than a general purpose bomber. A single Mk.V served as the prototype for this variant, and 146 Mk.VII were built at Baginton between 1941 and 1943, with additional Mk.V being converted as well. This variant, had to carry an additional crew member to operate the ASV Mk.2 radar arrangement, together with an increased fuel capacity for long endurance anti-shipping missions. Some Mk.VII were converted to trainers late in the war with additional seating and instrumentation for flight engineers.

Early variants of the Whitley featured bomb bay doors, fitted on both fuselage and wing bays which were hold by bungee cords. During bombing operations, the doors were opened by the weight of the falling bombs, and closed again by the bungee cord. This caused a short and unpredictable delay for the doors to open, making the bomb aiming highly inaccurate. The Mk.III introduced hydraulically actuated doors which greatly increased bombing accuracy. In order to aim the bombs, the bomb aimer opened a hatch located at the nose of the aircraft, which extended the bomb sight out of the fuselage. This system was replaced in the Mk.IV with a slightly extended plexiglas panel, making it more comfortable.

Sources:

1. https://en.wikipedia.org/wiki/Armstrong_Whitworth_Whitley

2. https://www.valka.cz/Armstrong-Whitworth-A-W-38-Whitley-Mk-VII-t6571

3. https://www.valka.cz/Armstrong-Whitworth-A-W-38-Whitley-Mk-IV-t6569

4. https://www.valka.cz/Armstrong-Whitworth-A-W-38-Whitley-Mk-V-t6570

5. Hall Park Books - Warpaint 21 - Armstrong Whitworth Whitley