Wheel slip with road tyre and wet road

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Smokes
4
Joined: 30 Mar 2010, 17:47

Wheel slip with road tyre and wet road

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Dumb question, but with a road tyre if you hit throttle hard enough to break traction on a wet road. even if the trye is slipping does it still generate forward traction abielt small and is it linear until the tractive velocity of matches the velocity of the body?

Just heard a car with TC slip cut slip cut and slip before it gained traction, i just wondering if algorythms used in road car TC is not that good.

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strad
117
Joined: 02 Jan 2010, 01:57

Re: Wheel slip with road tyre and wet road

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Depends on the make of car...some use the brakes, some like my Ford simply cut the fuel supply.
To achieve anything, you must be prepared to dabble on the boundary of disaster.”
Sir Stirling Moss

Scootin159
9
Joined: 06 Aug 2009, 21:09

Re: Wheel slip with road tyre and wet road

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The tire generates less traction the more it slips, but it will still always generate some traction. That's why when you see a car do a burnout it still moves forward slightly (unless the driver also hits the brakes). The peak amount of grip actually comes from a tire that is just ever so slightly slipping.

TC is another matter - most older systems do just as strad says, they apply the brakes as needed to prevent one wheel from spinning significantly faster than the rest. Newer systems will also cut engine power (to prevent overheating the brakes). From a performance standpoint though neither is typically tuned for maximum acceleration, but is instead tuned with a huge range of error (to account for large variables in tires, maintenance and surface conditions) with the intentions of making it easier for your grandmother to avoid spinning the tires.

A true race-mode TC system (such as we used to see in F1) would need to be trained for the specific tire installed (in F1 they had switches to adjust for the variable diameter in different compounds), as well as to account for the grip available on the given surface (the F1 cars had a 'learn' mode they used in practice starts). A good system will also allow you to turn back the acceleration a little to save your rear tires.

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