Editing Donald Campbell (section)

== Water speed records ==
{{More citations needed|section|date=February 2024}}
[[File:Bluebird K7 in 1960 at Goodwood.jpg|thumb|left|''Bluebird K7'' on display at Goodwood Motor Racing circuit in 1960]]
Campbell began his speed record attempts in the summer of 1949, using his father's old boat, ''[[Blue Bird K4]]'', which he renamed ''Bluebird K4''. His initial attempts that summer were unsuccessful, although he did come close to raising his father's existing record. The team returned to [[Coniston Water]], [[Furness|Lancashire]]<!-- Do not change to Cumbria, it did not exist prior to 1974 --> in 1950 for further trials. While there, they heard that an American, [[Stanley Sayres]], had raised the record from {{Convert|141|to|160|mph|abbr=on}}, beyond K4's capabilities without substantial modification.

In late 1950 and 1951, ''Bluebird K4'' was modified to make it a "prop-rider" as opposed to her original immersed propeller configuration. This greatly reduced hydrodynamic drag:  The third planing point would now be the propeller hub, meaning one of the two propeller blades was always out of the water at high speed. She now sported two cockpits, the second one being for Leo Villa.

''Bluebird K4'' now had a chance of exceeding Sayres' record and also enjoyed success as a circuit racer, winning the Oltranza Cup in Italy in the spring of that year. Returning to Coniston in September, they finally got ''Bluebird'' up to 170&nbsp;mph after further trials, only to suffer a structural failure at {{Convert|170|mph|km/h|abbr=on}} which wrecked the boat. Sayres raised the record the following year to {{Convert|178|mph|abbr=on}} in Slo-Mo-Shun IV.

Along with Campbell, Britain had another potential contender for water speed record honours&nbsp;— [[John Cobb (racing driver)|John Cobb]]. He had commissioned the world's first purpose-built turbojet [[Hydroplane (boat)|Hydroplane]], ''[[Crusader (speedboat)|Crusader]]'', with a target speed of over {{Convert|200|mph|abbr=on}}, and began trials on [[Loch Ness]] in autumn 1952. Cobb was killed later that year, when Crusader broke up, during an attempt on the record. Campbell was devastated at Cobb's loss, but he resolved to build a new ''Bluebird'' boat to bring the water speed record back to Britain.

In early 1953, Campbell began development of his own advanced all-metal jet-powered ''[[Bluebird K7]]'' hydroplane to challenge the record, by now held by the American prop rider hydroplane Slo-Mo-Shun IV.[1] Designed by Ken and Lew Norris, the K7 was a steel-framed, aluminium-bodied, three-point hydroplane with a Metropolitan-Vickers Beryl axial-flow turbojet engine, producing 3,500-pound-force (16&nbsp;kN) of thrust.

Like Slo-Mo-Shun, but unlike Cobb's tricycle Crusader, the three planing points were arranged with two forward, on outrigged sponsons 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 and stressed to 25 g (exceeding contemporary military jet aircraft). It had a design speed of {{Convert|250|mph|km/h|abbr=off}} and remained the only successful jet-boat in the world until the late 1960s.

The designation "K7" was derived from its Lloyd's unlimited rating registration. It was carried on a prominent white roundel on each sponson, underneath an infinity symbol. ''[[Bluebird K7]]'' was the seventh boat registered at Lloyds in the "Unlimited" series.

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 {{Convert|202.32|mph|km/h|abbr=on}} but only after many months of trials and a major redesign of ''Bluebird''{{'}}s forward sponson attachments points. Campbell achieved a steady series of subsequent speed-record increases with the boat during the rest of the decade, beginning with a mark of {{Convert|216|mph|km/h|abbr=on}} 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 latter half of the 1950s, enjoying significant sponsorship from the Mobil oil company and then subsequently BP.

Campbell also made an attempt in the summer of 1957 at [[Canandaigua (city), New York|Canandaigua, New York]], which failed due to lack of suitable calm water conditions. ''Bluebird K7'' became a well known and popular attraction, and as well as her annual Coniston appearances, ''K7'' was displayed extensively in the UK, United States, Canada and Europe, and then subsequently in Australia during Campbell's prolonged attempt on the land speed record in 1963–1964.

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 {{Convert|225|mph|km/h|abbr=on}} in 1956, where an unprecedented peak speed of {{Convert|286.78|mph|km/h|abbr=on}} was achieved on one run, {{Convert|239|mph|km/h|abbr=on}} in 1957, {{Convert|248|mph|km/h|abbr=on}} in 1958 and {{Convert|260|mph|km/h|abbr=on}} in 1959.

Campbell was named as a [[Commander of the British Empire]] (CBE) in January 1957 for his water speed record breaking, and in particular his record at [[Lake Mead]] in the United States which earned him and Britain very positive acclaim.

On 23 November 1964, Campbell achieved the Australian water speed record of {{convert|216|mph|km/h}} on [[Lake Bonney Riverland]] in [[South Australia]], although he was unable to break the world record on that attempt.<ref>{{cite web | title= Press Release - Bluebird Replica Build Begins | website=K7 Project Bluebird Barmera Australia | date=31 December 2014 | url=https://www.bluebird-electric.net/bluebird_history/K7_Project_Bluebird_Barmera_Australia.htm | access-date=27 August 2020}}</ref><ref>{{cite web | title=Donald Campbell's Water Speed Record Attempt | website=Monument Australia | url=https://www.monumentaustralia.org.au/themes/culture/sport/display/50429-donald-campbell%60s-water-speed-record-attempt | access-date=27 August 2020}}</ref>