Will Gray

Technical Talk: Back to the title battle

Will Gray

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The title race gets back on track this weekend in Valencia but which of the two main contenders will the street circuit suit best?

The last race, in Budapest, saw Lewis Hamilton put McLaren back at the front with his first win of the year, but - whether they remain ahead or not after the summer break - the most important battle in terms of the championship will be the relative supremacy between Red Bull and Brawn, wherever they are on the grid.

Brawn fell back in recent races after Red Bull introduced a significant development package and McLaren's return to the front has not helped matters for the old Honda squad. This weekend they will be hoping their car is suited better to the streets of Valencia than it has been to the tracks in Hungary, Germany and Silverstone.

The circuit, which arrived on the calendar last year, has a street layout look and feel and although it is far removed from Monaco in terms of its average speed (which is higher here than on most other city tracks) it retains one of the most important factors of temporary tracks, that of low base surface grip.

The grip of the tarmac itself is generated from two elements. Firstly, it is dependent on how closely the stones in the tarmac are spaced and secondly it is affected by the roughness of the stones themselves. On top of that, regular race circuits have extra grip provided by rubber laid down by previous racing - but on temporary tracks such as Valencia, where previous running has been severely limited, there is naturally limited grip.

As the surface is 'green' due to a lack of racing during the rest of the year, and it will constantly change throughout the weekend - making grip levels unpredictable. This is going to make tyre choice exceptionally difficult for the race itself, with the relative grip and wear levels of the softer and harder compounds likely to remain unclear.

With a low-grip track, more grip must be generated from the tyre, which is affected mostly by temperature.

One thing that seems an almost given in Valencia is a high ambient temperature, which obviously means a high track temperature, as the long-range forecast suggests a settled 34-36 degrees Celsius all week.

Additional temperature then gets into the tyres through the car's motion around the track, much of which comes from cornering and braking forces.

In Valencia, the circuit is relatively fast on average, but with long straights linking five hairpins and three medium-speed chicanes there are few high speed corners so the tyre wear from cornering forces is generally low. However, the transition between high-speed and slow corners means there is a large amount of braking, and that will see cars put heat into their tyres this way - but this will be less than it would if there were more high-speed corners.

Tyres work best in a range and if they get too hot it can turn to disaster. How the Brawn and Red Bull cars balance grip generation to tyre degradation will be a major factor in their relative performance in the race.

Meanwhile, as the battle for the title between Brawn and Red Bull goes on, other teams could be in the mix for individual race success with yet another upgrade from McLaren likely to help them build on their Hungary performance and Toyota, also successful in Hungary, expecting the track to suit their mid-level aero package better than any other circuit too.

So the two title contenders may have to contend with others for victory this weekend - but their eyes need only be firmly on each other.

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