Bluebird K7

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The wreckage of the tailfin of K7

Bluebird K7 is a jet engined hydroplane with which Britain's Donald Campbell set seven world water speed records (WSR) during the later half of the 1950s and the 1960s. K7 was the first successful jet-powered hydroplane, and was considered revolutionary when launched in January 1955. Campbell and K7 were responsible for adding almost 100 miles per hour (160 km/h) to the WSR, taking it from existing mark of 178 miles per hour (286 km/h) to just over 276 miles per hour (444 km/h). Donald Campbell was killed in an accident with a much modified K7, on 4 January 1967, whilst making a bid for his eighth WSR, with his aim to raise the record to over 300 miles per hour (480 km/h) on Coniston Water.

Donald Campbell began his record-breaking career in 1949 following the death of his father, Sir Malcolm Campbell. Initially, he had been using his father's 1939-built Rolls-Royce 'R' type powered propeller-driven hydroplane Bluebird K4 for his attempts, but he met with little success and suffered a number of frustrating setbacks. In 1951, K4, which had been modified to a prop-rider configuration to increase its performance potential, was destroyed after suffering a structural failure, when its V-drive gearbox sheared its mountings, and punched through the floor of the hull.

Following rival record breaker John Cobb's death in his jet boat Crusader, which broke up at over 200 miles per hour (320 km/h) during a record attempt in September 1952, Campbell began development of his own advanced all-metal jet-powered Bluebird K7 hydroplane to challenge the record, by then held by the American prop rider hydroplane Slo-Mo-Shun IV. Designed by Ken and Lew Norris, the K7 was a steel-framed, aluminium-bodied, three-point hydroplane, built at Samlesbury by Samlesbury Engineering, powered by a Metropolitan-Vickers Beryl axial-flow turbojet engine, producing 3500 pound-force (16 kN) of thrust. Like Slo-Mo-Shun, but unlike Cobb's tricycle Crusader, the three planing points were arranged with two forward and one aft, in a "pickle-fork" layout, prompting Bluebird's early comparison to a blue lobster. K7 was of very advanced design and construction, and its load-bearing steel space frame ultra rigid. It had a design speed of 250 miles per hour (400 km/h) and remained the only successful jet-boat in the world until the late 1960s.