Sunderland Mk II, W6055, ZM-R, No.201 Squadron, Castle Archdale, September 1942 The Sunderland Mk II, built from August 1941, was powered by Pegasus XVIII engines with two-speed superchargers, each producing 1,065hp. The tail turret was changed to an FN.4A turret which still mounted four 0.303in Browning machine guns but with twice the ammunition capacity, a staggering 1,000 rounds per gun. Like the Mk I, the Mk II had a sharp-edged ’step’ in the hull. From October 1941, Sunderlands began to receive ASV Mk II ‘air-to-surface vessel’ radar. This primitive low frequency radar used a row of four prominent ‘stickleback’ yagi antennas on top of the rear fuselage, augmented by two rows of four smaller aerials on each side of the fuselage, and by a single receiver aerial mounted under each wingtip. The aircraft has white undersurfaces with camouflaged top-sides, reducing conspicuity from below.