The Gloster Garrison Bomber

**Spinners** · August 26, 2018

Gloster Garrison B.I - 101 Squadron, RAF Bomber Command, 1937

In 1932, the Air Ministry issued Specification B.9/32 for a twin-engined day bomber with a challenging demand for "higher performance than any preceding bomber aircraft" and, among others, the Gloster Aviation Company responded with a mid-wing cantilever monoplane featuring all-metal stressed-skin construction, retractable landing gear, flaps, a powered dorsal gun turret, a ventral bomb bay and variable-pitch propellers. Like most of the companies tendering to B.9/32, Gloster's design featured the politically-favoured Rolls-Royce Goshawk 'evaporative' (steam cooled) engine but by the end of 1933 Gloster could see that the Goshawk engine would seriously degrade flight performance due to the larger then expected size of the condensors required to turn the steam vapour back into liquid.

Gloster's chief designer, Henry Folland, turned to his long-time friends at the Bristol Engine Company who were planning a new 14-cylinder twin-row sleeve valve radial engine as a development of their existing single-row Aquila engine by adding another row of cylinders and transforming it into the Bristol Taurus twin-row radial engine. With an anticipated power output of 1,000 hp and with very low weight, Folland quickly redesigned his bomber around two of the proposed Bristol Taurus engines and boldly reduced the crew from four to two by removing the defensive armanent and the bombardier's station. Folland briefed RAF and Air Ministry officials on his unarmed fast bomber and mainly due to the support of Edward Ellington, the Chief of the Air Staff, Folland was rewarded with a new Specification B.40/34 to cover his new design soon officially named as the Gloster Garrison. Ellington soon followed up this support with a production contract for 250 Gloster Garrison aircraft as part of 'Scheme F' an ambitious plan to increase the size of the Royal Air Force to 187 squadrons within three years to counter the threat from Hitler's Germany. Such was the dominance of "the bomber will always get through" strategy at the time that Ellington demanded five bomber squadrons for every two fighter squadrons and he saw that this unarmed fast bomber could play an important role in his expansion plans.

With development of the airframe running slightly ahead of the Taurus engine, all Garrison prototypes were powered by two 840 hp Bristol Mercury VIII radial piston engines and these were good enough to demonstrate the aircraft's performance and handling and also that the design was a good bombing platform. With continued delays in the development of Taurus engine the first production aircraft retained the Bristol Mercury VIII engines and following the completion of handling trials, conducted at the Central Flying School at Upavon in Wiltshire, the Garrison B.I entered RAF squadron service with No.49 Squadron at Scampton in August 1937 and No.101 Squadron at Bircham Newton in October 1937.