Boulton Paul Overstrand

The Overstrand was a development of the Boulton Paul Sidestrand, which had first flown in 1928 and like the Sidestrand was named for a village in Norfolk, home also of Boulton Paul’s Norwich factory. The Sidestrand was similar to its First World War predecessors, in that it had open cockpits and hand-operated machine-guns. Unlike its predecessors, the Sidestrand could fly at 140 mph (230 km/h) making operating the guns in exposed positions difficult, particularly in the nose. The Overstrand was fitted with an enclosed and powered nose turret with a Lewis gun, the first RAF aircraft to have a power-operated turret. Traverse of the turret was driven by pneumatic motors, elevation and depression of the gun by hydraulic rams. The cockpit was also enclosed but the dorsal and ventral gun positions remained open, though shielded.

The first Overstrand flew in 1933 as the Sidestrand Mk IV, powered by two 580 hp (430 kW) Bristol Pegasus IM.3 engines, instead of the 460 hp (340 kW) Bristol Jupiters in the Sidestrand and was capable of 153 mph (246 km/h). The bomb load was also increased to 1,500 lb (680 kg). The conversion was a success and three more Sidestrands were modified using the 580 hp (430 kW) Bristol Pegasus II.M3. 24 Overstrands were produced and in 1936 began replacing the Sidestrand in No. 101 Squadron RAF, the only Sidestrand squadron and briefly in No. 144 Squadron RAF, being replaced by Bristol Blenheims in 1938. At the outbreak of the Second World War, eleven Overstrands remained in service and six were used for gunnery training. They remained in operation until May 1941, though flying was limited following the mid-air breakup of Overstrand K8173 on 22 April 1940.