Technical Focus: The Rain-Men
		by Will Gray, England

The constant threat of rain at Silverstone for the British Grand Prix was not just a pain for the spectators. Many drivers dislike the rain, and such conditions can often turn the competition into a lottery. But, it is for this very reason that some teams lower down the grid enjoy such conditions. For those at the circuit, rain presents a damp, unpleasant environment to work in - but that is the least of a team's worries when they see the dark clouds looming. Obviously, rain can be present in varying amounts, and a 'wet' track can mean many things - just look at the circuit which was declared a 'wet track' on Saturday afternoon, and compare it to that of Friday practice. You see, the difficulty with wet conditions, for teams and drivers, is down to ever changing levels of grip - with the present day cars acting like a hoover and power hose all in one, the water is rapidly shifted off line. The aerodynamics of the modern racing car provide substantial downforce and, through Newton's laws of Action-Reaction, to every downward force, there must be an opposing upward force. This is clear to see when the track is wet, with plumes of spray kicking up from the rear of the cars. The upward motion, combined with the turbulence creating swirling air ensures the moisture that was once happily resting on the track is removed. This causes two major headaches for the drivers. Firstly, there is the problem of visibility. We've all heard the analogies of following a truck on a motorway, or driving at speed in dense fog, but it is quite simply impossible to comprehend traveling so fast in such conditions. This is probably because no-one in their right mind would do such a thing unless they had to! Sometimes even F1 drivers see sense and give in to the conditions - most famously Niki Lauda in Fuji, Japan, 1976, where he lost the championship to James Hunt, or Alain Prost, who was famed for his fear of the wet stuff, claiming racing in the rain was nothing more than a game of chance. However, with the modern Formula One being such a global media event, the show must go on. The teams must be able to cope with the conditions, and this is where an ever drying track can cause problems - as we saw last Saturday at the British Grand Prix. Rain is acknowledged as a great leveller. A car has a limit - it's downforce and mechanical grip mean it has an ultimate, achievable, on-the-limit lap time (that is, if the driver can drive it on its limit). But the limit of adhesion is given by the grip levels offered by the car, and the adhesion of the track. In the dry, the level of adhesion offered by the track is such that the limiting factor is the car, so the cars with more downforce and mechanical grip will go faster. When the surface becomes wet, the grip offered by the track is lower, and this becomes the limit of adhesion. The first thing a team will do is put on a whole heap of downforce - the more force they can put on the tyres, the more grip they will attain - but once they have done this, the limit is determined by the track, and how much grip it can provide - it is therefore more about the driver. For them, once out on the track, it is a question of finding the limit. This is the case in wet or dry, but in the wet the difficulty is that the limit is constantly changing not just every lap, but around the lap. At Silverstone, it was clear that whilst some corners drained well, others left puddles of water on the racing line. The risk of the car swapping ends is great, and any white lines or painted kerbs present great danger for the unsuspecting driver - just look at Nigel Mansell's white-line experience at Monaco in 1985. The message is clear: Stay off the kerbs in the wet. But if a driver is unfortunate enough to find himself exiting stage left, the rain presents yet another danger. A slippery track can mean a driver may spin in an unusual area, where gravel traps are not usually considered. He can then be faced with the dangerous situation of 'acceleration-grass', speeding the car towards the barrier rather than slowing it to rest - trick is, then, not to get out of shape! Undeniably, the greatest challenge in the wet is working with the changing limit level. In qualifying, there are only twelve laps available to set a time, so it is essential to use these sparingly. The first step is to position spotters around the circuit and surrounding area, as it is important to see where the weather is coming from, and what it is likely to do. If the black clouds are looming, then you have to time it just right and get out before the rain comes, but if there's sun on the way, that means the track will dry, and there's no point in setting a wheel out of the garage until the end of the session. Playing the weather is never more important. Although the days of intermediates are gone, leaving teams with a choice of just wet or dry, tyres are still quite critical. A wet tyre has three important criterion. Firstly, the v-shaped channels in the tread will move standing water from the front of the contact patch, to the sides and out. In addition to this, there are pores on the tyres which absorb the moisture to create a dry section of track under the contact patch, which finally allows the compound to create adhesion with the surface. With all cars on the same type of tyre, there is still the possibility of variability. In very wet conditions, wets are clearly the way to go, but when the circuit begins to dry, the wet tyres 'go off' easily - that is to say, they lose grip rapidly due to chemical changes in the compound, when the heat of the track rises above the temperature they are designed for. To avoid this situation in qualifying, teams can scrub down their wet tyres to remove rubber from them, which lessens the speed at which the tyres will go off. Also, a driver can elect to go for one hot lap, then take a breather for a lap, running different lines to normal to find the wet patches and cool the tyres down, before going for another fast one. At the right time, another option, for the brave, is to go for dry tyres. This can make a hero of a driver, as if the track has dried to the right level, a car on drys can be literally seconds ahead of one on wets. If that decision is made right at the end of a qualifying session, then the grid can be quite unusual. Even when the track is suitable for dry tyres, the conditions still constantly improve - as was the case at Silverstone qualifying. All runners were on dry tyres way before the session ended, but the track was still drying, and success was all about timing. A driver will want to leave his run to the very last second to take advantage of the driest track - because with so many cars out at the end, the track is forever getting faster. However, if that one run is disrupted by traffic, then he's lost his chance. As Alain Prost might argue, it's all a bit of a lottery really.

Will Gray	© 2000 Kaizar.Com, Incorporated.
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