1950s. Slo-Mo-Shun and Bluebird: Propriders To Turbojets
Early in the morning of 26 June 1950 a small red boat skipped across Lake Washington, near Seattle, and improved on Campbell's record by 29 km/h (18 mph). The boat was called Slo-Mo-Shun IV, and it was built by Seattle Chrysler dealer Stanley Sayres. The piston-engined boat was able to run at 160 mph (260 km/h) because its hull was designed to lift the top of the propellers out of water when running at high speed. This phenomenon, called ‘prop riding’, further reduced drag.
In 1952 Sayres drove Slo-Mo-Shun to 287.25 km/h (178.49 mph) - a further 29 km/h (18 mph) increase. The renewed American success persuaded Malcolm Campbell's son Donald, who had already driven Bluebird K4 to within sight of his father's record, to make a further push for the record. However, the K4 was by now 12 years old, with a 20 year old engine and Campbell struggled to run at the speeds of the Seattle-built boat. In late 1951 K4 was written-off when it suffered a structural failure at 170 mph (270 km/h) on Coniston Water.
At this time, yet another land speed driver entered the fray. Englishman John Cobb, was hoping to beat 320 km/h (200 mph) in his jet-powered Crusader. A radical design, the Crusader reversed the ‘three-pointer’ design, placing the floats at the rear of the hull. On 29 September 1952 Cobb tried for a 320 km/h (200 mph) record on Loch Ness. Travelling at an estimated speed of 210 mph (340 km/h), Crusader's front plane collapsed and the craft instantly disintegrated. Cobb was retrieved from the water but had already died of shock.
Two years later, on 8 October 1954, another man would die trying for the record. Italian textile magnates Mario Verga and Francesco Vitetta, responding to a prize offer of 5 million lire from the Italian Motorboat Federation to any Italian who broke the world record, built a sleek piston-engined hydroplane to claim the record. Named Laura III, after Verga's daughter, the boat was fast but unstable. Travelling across Lake Iseo, in Northern Italy, at close to 306 km/h (190 mph), Verga lost control of Laura III, and was thrown out into the water when the boat somersaulted. Like Cobb, he died of shock.
Following Cobb's death, Donald Campbell started working on a new Bluebird - K7, a jet-powered hydroplane. Learning the many lessons from Cobb's ill-starred Crusader, K7 was designed as a classic 3 pointer with sponsons forward alongside the cockpit.
The 26 ft (7.9 m) long, 10 ft (3 m) wide, 5 ft (2 m) high, 2.5 ton craft was designed by Ken and Lewis Norris in 1953-54 and was completed in early 1955. It was powered by a Metropolitan-Vickers Beryl turbojet of 3500 lbf (16 kN) thrust. K7 was of all metal construction and proved to have extremely high rigidity.
Campbell and K7 set a new record of 325.60 km/h (202.32 mph) on Ullswater in July 1955. Campbell and K7 went on to break the record a further six times over the next nine years in the USA and England (Coniston Water), finally increasing it to 444.71 km/h (276.33 mph) at Lake Dumbleyung in Western Australia in 1964. Donald Campbell thus became the most prolific water speed record breaker of all time.
At this time that the world speed record (200.42 mph) for piston-powered propeller-driven boats was held by the Miss U.S. I owned by George Simon. This record was set at Guntersville, Alabama in 1962 by Roy Duby. This record stood for 38 years.
Read more about this topic: Water Speed Record