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TEAM TALK
Solberg - The fastest road sweeper in New Zealand
Letter from SWRT
9 April 2005
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| Copyright © STI |
Road sweeping, clean lines and road cleaning have been the hot topics of conversation during the first Leg of Rally New Zealand. Subaru Team Principal David Lapworth explains what it all means, and how the team has coped:
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The stages of Rally New Zealand and Rally Australia are probably the most well known for road cleaning, but all gravel stages will clear, to some extent, if the surface is dry. The scale of the effect depends on the nature of the road surface. Most gravel roads have a hard-packed rock and stone base covered with a loose layer of gravel, sand and mud. Each passing car cleans off some of the top layer and exposes more of the hard surface underneath. The amount of loose material, and the grip level of the surface that is exposed, determine how much the surface improves.
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| Copyright © STI |
In New Zealand today we've seen a lot of cleaning. After a long dry summer and on such well-made roads the base underneath is as hard and grippy as an asphalt road, while the loose top surface is quite thick. On Leg one we've seen that the first few cars sweep the road clean and lose a lot of time. Typically, the time lost is about 0.2 sec/km between the first two cars, and about 1 sec/km between the first and the 10th car.
The fact that the first and longest stage of the day was slightly damp certainly helped Petter. Overnight rain reduced the cleaning effect a little, as the hard surface that was exposed was slightly damp, and the cars following did not get such an advantage. This enabled Petter to take a slightly softer tyre compound, which gave him better grip and helped to compensate for his poor road position.
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2006
2005