Blue Bird K4 was a powerboat commissioned in 1939 by Sir Malcolm Campbell, to rival the Americans' efforts in the fight for the world water speed record.

The name "K4" was derived from its Lloyd's unlimited rating, and was carried in a prominent circular badge on the forward hull.

K4 was built by Vosper & Company as a replacement to the Blue Bird K3, which had set three other water speed records for Malcolm Campbell before the K4 was built. It also used the same Rolls-Royce R engine.

K4 was a three point hydroplane. Conventional planing powerboats, such as Miss England or Blue Bird K3, have a single keel, with an indent or "step" projecting from the bottom of the hull. At speed, the force on this step is enough to lift the bow upward, reducing the wetted surface area of the hull and thus also the frictional drag. A "three pointer" has a two distinctly separate floats fitted to the front, and a third point at the rear of the hull. When the boat increases in speed, most of the hull lifts out of the water and planes on these three contact points alone. These points being even smaller in area than the planing hull of a monohull hydroplane, have even less drag. Having a broad spacing between the front planing points, the three-pointer is less susceptible to instability caused by small disturbances than is a monohull. However if the bow lifts beyond its safety margin, the aerodynamic forces (not the hydrodynamic forces of the water) on the broad forward area of the hull will cause it to "kite" upwards, leading to a somersault and crash. This is what happened to both Slo-mo-shun and Bluebird K7 (see below).

K4 set one world water speed record on 19 August 1939 on Coniston Water, Cumbria, England.

THE JET AGE

After World War II, in 1947 Sir Malcolm re-engined K4 with a de Havilland Goblin II turbojet engine and Vosper substantially modified the hull. The new configuration had first trials at Coniston Water on 13th June 1947, but proved unstable and uncontrollable at speeds approaching 90 mph. K4 was returned to Vosper's for further modifications, then taken down to Poole, in Dorset where further trials were carried out, these trials proved favourable. 

Returning to Coniston a week later for trials and an attempt on the record, its was found that the boat had now developed a tendency to porpoise at speeds over 100 mph with such violence that Sir Malcolm was nearly thrown from the cockpit. A record attempt was made on the following day and while Sir Malcolm gave it his best, he was unable to get the boat up to record speed because of the handling problems. He didn't gain any records, but the new superstructure gained the nickname 'The Coniston Slipper'. Sir Malcolm died the following year of a stroke..

SIR MALCOLM'S WATER SPEED RECORDS

1st September 1937: 126.33 mph Blue Bird K3, Sir Malcolm Campbell,Lake Maggiore, Switzerland

2nd September 1937: 129.56 mph Blue Bird K3, Sir Malcolm Campbell, Lake Maggiore, Switzerland

17th September 1938: 130.93 mph Blue Bird K3, Sir Malcolm Campbell, Lake Hallwyl, Switzerland

19th August 1939: 141.74mph Blue Bird K4, Sir Malcolm Campbell, Coniston Water, England

DONALD CAMPBELL

Donald Campbell had not previously attempted record-breaking, but after Sir Malcolm's death at the end of 1948, the threat of an American challenge to his water speed record spurred him to defend it. Under the terms of his will, Sir Malcolm's possessions, including the record breakers, were auctioned off and Donald was forced to buy them back. K4 was then re-engined with a propeller and one of the previous Rolls-Royce R engines.

Donald tried unsuccessfully to break his father's record with the K4. The boat was deemed too slow, so after another superstructure rebuild and finally structural failure it was replaced by the jet-powered K7, in which Donald died during a record attempt in 1967. The boat sank in 1951 at Coniston Water

A replica of K4 currently is on show at the Lakeland Motor Museum, Backbarrow.

SLO MO SHUN

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. 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.

JOHN COBB

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. It would be ten years, but Campbell and the K7 were to suffer a similar fate. 

Donald Campbell's daughter, Gina, was also to somersault her racing boat, but would cheat death. Since that time, no member of the Campbell bloodline has dared to put his or her toe in the water, or attempt the outright land speed record. The water speed record is a dangerous business; one cannot blame them. These days thee outright land speed record requires the skills of an aviator - and that has probably set the bar too high.

SIR MALCOLM CAMPBELL'S BLUE BIRDS

Sunbeam

Napier Lion

Rolls Royce

K3

K4

DONALD CAMPBELL'S BLUEBIRDS

K7

CN7

CNM8