In 1956, Donald Campbell began planning a car to break the land speed record, which then stood at 394 mph (630 km/h).

The Norris brothers designed ‘Bluebird-Proteus CN7’ with 500 mph (800 km/h) in mind.

CN7 was completed by the spring of 1960, and was powered by a Bristol-Siddeley Proteus free-turbine engine of 4,450 shp.

Following low-speed tests conducted at the Goodwood circuit in Sussex, England, the CN7 was taken to the Bonneville Salt Flats in Utah, USA, scene of his father's last LSR triumph in 1935.

The attempt was unsuccessful, CN7 being written -off following a high-speed crash in September at Bonneville. Campbell was seriously hurt, suffering a fracture to his lower skull. His confidence was also severely shaken and for some time he doubted if he would ever return to record breaking.

As part of his recuperation he learned to fly light aircraft and this boost to his confidence was an important factor in his recovery. By 1961 he was on the road

 

The rebuilt car was completed, with modifications including a large vertical stabilizer, in 1962. The omission of such a tail in the first place was unusual, as their necessity at such speeds had been recognised since the 1930s. By the end of the year she was shipped to Australia for a new attempt at Lake Eyre in 1963. The Lake Eyre location was chosen as it offered 450 square miles (1,170 km2) of dried salt lake, where rain had not fallen in the previous 20 years, and the surface of the 20 miles (32 km) long track was as hard as concrete. As Campbell arrived in late March, with a view to a May attempt, the first light rain fell. Campbell and Bluebird were running by early May but once again more rain fell, and low-speed test runs could not progress into the higher speed ranges. By late May, the rain became torrential, and the lake was flooded. Campbell had to move the CN7 off the lake in the middle of the night to save the car from being submerged by the rising flood waters. The 1963 attempt was over.

 

Campbell and his team returned to Lake Eyre in 1964, but the surface never returned to the promise it had held in 1962 and Campbell had to battle with CN7 to reach record speeds (over 400 mph/640 km/h).

 

After more light rain in June, the lake finally began to dry enough for an attempt to be made and on July 17, 1964, Campbell set a record of 403.10 mph (648.73 km/h) for a four-wheeled vehicle (Class A). Campbell was disappointed with the record as the vehicle had been designed for much higher speeds. CN7 covered the final third of the measured mile at an average of 429 mph (690 km/h), peaking as it left the measured distance at over 440 mph (710 km/h).

 

CN7, a potted history...