When Richard Noble and the Thrust 2 team took their car to America for the first time in 1981, they went to the Bonneville Salt Flats of Utah, described by some as the ‘spiritual home of record breaking’. It is now a matter of record that Thrust 2 did not like the concrete hard surface - it skated around like it was being driven on ice, and the jarring in the cockpit was almost insufferable. To this day, Richard Noble talks of having the car ‘sideways’ at speeds of up to 300mph.

It is interesting to note that Art Arfons, Rosco McGlashan and many of the Bonneville cars all suffered similar serious stability problems when trying to run solid-wheel record cars on the salt.

Why was this? Previous record attempts on rubber-tyred wheels had had no such problem - rubber grips the salt better than it grips tarmac or asphalt, and is offered a degree of cooling by the surface. With the ever increasing speed being attained by the jet-cars, rubber tyres had reached the limits of their capabilities - it is said that the cost of development of 750 mph tyres would probably equal that of building Spirit of America in the first place. ThrustSSC's wheels, for example, are solid aluminium, rotate to 8,500rpm and accept a wheel rim radial acceleration of 35,000g. All the current contenders for the LSR are using solid wheels.

When the 1982 attempt at Bonneville was washed out by the onset of the winter rains, by a huge stroke of luck the Thrust 2 team found an alternative in the Black Rock Desert near Gerlach, Nevada. Black Rock proved to have a huge advantage over Bonneville - rather than a coating of unyielding hard salt, it comprised a vast expanse of alkaline mud playa - dried alluvium that had washed off the hills and settled to leave a perfectly flat surface. Firm, but yielding enough to allow the car’s wheels to obtain the grip, ride and stability Noble needed to keep it in a straight line, Black Rock Desert and Thrust 2 suited each other perfectly.

With the experience of Thrust 2 behind them, the ThrustSSC team have always targeted alkaline mud playa deserts as their intended surface. Jafr Desert, Jordan, is another example which, although shorter, provides a harder and more consistent surface than Black Rock.

Everything is a compromise, and the downside of a dried mud surface is drag - Thrust 2 required every pound of thrust from her Avon 302 engine to break Gary Gabelich’s existing record by a bare 2%. Increased drag means slower acceleration, more fuel weight and possibly a slower top speed. But if the alternative surface does not provide the necessary car stability in the first case - the maximum speed becomes academic.

It is now a matter of public knowledge that ThrustSSC’s chief competitor in the attempt to break both Noble’s existing record (of 633.468mph) and the sound barrier (at around 750mph), Craig Breedlove, is planning to make his first trials on the Bonneville salt. The Utah site has a huge number of other advantages. The BLM annually create the track system - the salt hosts a number of events including the famous Bonneville Speed Week - and the large town of Wendover with its airfield is well used to providing the necessary facilities. Black Rock on the other hand has only the small communities of Gerlach and Empire nearby and the entire record bid infrastructure needs creation.

The question remains: "Alkali or Salt?"

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