Bluebird K7
Bluebird K7 is a jet engined hydroplane in which Britain's Donald Campbell set seven world water speed records between 1955 and 1967. 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 to the water speed record, taking it from existing mark of to just over. Donald Campbell was killed in an accident with a much modified K7, on 4 January 1967, whilst making a bid for his eighth water speed record, with his aim to raise the record to over on Coniston Water.
In 1996, a diving team using sonar equipment started an underwater survey, locating anew the K7 wreckage. Subsequently, it was recovered between 2000 and 2007, while Campbell's body was recovered in 2001.
Design and engineering
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 Blue Bird 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 which were 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 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 Norris Brothers, Ken and Lew, 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 using electric start with external battery pack, producing 3500 pound-force 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 and remained the only successful jet-boat in the world until the late 1960s.
From the brief of the mid 1950s, Blubird K7 was designed to:
- To attain a speed of 250 mph commensurate with an adequate margin of static and dynamic stability in yaw, pitch and roll.
- Very high structural strength and stiffness; the ‘g’ loadings were to be ‘... some three times that of “Crusader” and five times that of the old Bluebird.
- Low frontal profile area to minimise aerodynamic drag.
- Every attempt to minimise aerodynamic lifting moments forward of the Centre of Gravity.
- Paired forward sponsons mounted on outriggers to reduce loadings at the front planes.
- Planes to have high lift and low drag with good anti-porpoising capability, sponson under-surfaces to permit good transition from the displacement to the planing condition, and good anti-dive characteristics.
- Low CG to minimise potential pitching oscillations at the natural frequency of the craft.
- Turbojet propulsion with low thrust line to minimise thrust on/off moment effects.
- Fuel tank at or near the CG to minimise effects on trim due to fuel state.
''Bluebird K7'' records
Campbell set seven world water speed records in K7 between July 1955 and December 1964. The first of these marks was set at Ullswater on 23 July 1955, where he achieved a speed of 202.15 mph but only after many months of trials, changes to the inlet splash guards, and a major redesign of Bluebird's forward sponson attachments points by the raising of her front spar. Campbell achieved a steady series of subsequent speed-record increases with the boat during the rest of the decade, beginning with a mark of in 1955 on Lake Mead in Nevada. Subsequently, four new marks were registered on Coniston Water, where Campbell and Bluebird became an annual fixture in the later half of the fifties, enjoying significant sponsorship from the Mobil oil company and then BP. Campbell made an unsuccessful attempt in 1957 at Canandaigua in New York state in the summer of 1957, which failed due to lack of suitable calm water conditions. It was reported in the New York Times of 17 August 1957 that "Bluebird Leaves Water for 200 Feet When It Strikes Swell at 240 M.P.H." Bluebird K7 became a well known attraction, and as well as her annual Coniston appearances, K7 was displayed extensively in the UK, USA, Canada and Europe, and then subsequently in Australia during Campbell's prolonged attempt on the land speed record in 1963–64.In order to extract more speed, and endow the boat with greater high speed stability, in both pitch and yaw, K7 was subtly modified in the second half of the 1950s to incorporate more effective streamlining with a blown Perspex cockpit canopy and fluting to the lower part of the main hull. In 1958 a small wedge shaped tail fin housing an arrester parachute, modified sponson fairings that gave a significant reduction in forward aerodynamic lift, and a fixed hydrodynamic stabilising fin attached to the transom to aid directional stability and exert a marginal down-force on the nose were incorporated into the design to increase the safe operating envelope of the hydroplane. Thus she reached in 1956, where an unprecedented peak speed of was achieved on the first run, in 1957, in 1958 and in 1959.
In 1958, Donald Campbell with his team took Bluebird K7 to the Brussels World's Fair. K7 became a centrepiece to the British stand. The publicity event continued to Lake Bourget close to Aix Les Bains, where in June 1958 K7 was shown at the annual festival.
Campbell then turned his attention to the land speed record, with the aim of establishing a land speed record of plus. He also planned to set a seventh water speed record in the same year, and so become the first person to establish the land speed record and water speed record in the same year. He set out for the Bonneville Salt Flats in August 1960 and was lucky to survive a crash in his Norris Brothers designed Bluebird CN7 turbine powered car later that September. Bluebird CN7 was rebuilt in 1961–62 and Campbell subsequently spent a frustrating two years in the Australian desert, battling adverse track conditions. Finally, after Campbell exceeded the land speed record on Lake Eyre on 17 July 1964, at in Bluebird CN7, he snared his seventh water speed record on 31 December 1964 at Dumbleyung Lake, Western Australia, when he reached, with two runs at and completed with only hours to spare on New Year's Eve 1964.
This latest success made Campbell and K7 the world's most prolific holders of the water speed record, and in addition Campbell realised his 'double' when he became the first, and so far only, person to break both the land speed record and the water speed record in the same year. Following on from this success, Campbell stated that K7 would be most likely retired and become a museum exhibit. Her hull was ten years old, her engine fourteen, and her design speed of had been exceeded by over on a number of occasions.
Donald Campbell's water speed records
Donald Campbell had two Metrovick Beryl engines that were interchangeable during K7's life. These were used in achieving all of his seven K7 records. The Beryl engines were used from 1955 until 1966.Final record attempt and death of Donald Campbell
In June 1966, Campbell decided to once more try for a water speed record with K7: his target, 300 mph.To add more power, Campbell received a 4,500 pound-force Bristol Siddeley Orpheus engine on loan from the Ministry of Defence. This was both lighter and more powerful than the original engine. Campbell also purchased a crash-damaged Folland Gnat, which used the Orpheus engine, as a source of spare parts. The vertical stabiliser from the Gnat was also used on the rebuilt K7, and a new hydraulic water brake designed to slow the boat down on the five-mile Coniston course. Also changed in the 1966 redesign, was the start system: "The compressed air starting system, designed and manufactured by Rotax Ltd for the Orpheus engine in the Hunting H126 and Folland Gnat aircraft, was adapted for use in Bluebird. The system comprised two spherical air bottles containing 39lbs of dehumidified air, compressed to over 3,000psi. The bottles... were charged by means of a high-pressure, three-stage compressor, complete with air-drying and cleaning facility, housed in a specially adapted Land Rover vehicle."
The boat returned to Coniston for trials in November 1966. These did not go well; the weather was appalling and K7 destroyed her engine when the air intakes collapsed under the demands of the more powerful engine, and debris was drawn into the compressor blades. The engine was replaced, using the engine from the Gnat aircraft that he had purchased at the project's start. The original Orpheus remained outside the team's lakeside workshop for the rest of the project, shrouded in a tarpaulin.
By the end of November, after further modifications to alter K7 's weight distribution, some high-speed runs were made, but these were timed at well below the existing record. Problems with the fuel system meant that the engine could not develop maximum power. By the middle of December, Campbell had made a number of timed attempts, but the highest speed achieved was 264 mph, and therefore still shy of the existing record. Eventually, further modifications to K7's fuel system fixed the fuel-starvation problem. It was now the end of December and Campbell was all set to proceed, pending only the arrival of suitable weather conditions.