Hypothetical question
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Pro
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From: brooklyn ny
Tech Contributor
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Under your rules the time would be fairly long. You need some tire spin to get max acceleration. The tires have to slip somewhere around 17% to get max traction. They found this out at the dawn of timed drag racing when cars were going through the quarter mile with ETs that were less than theoretically possible. That was when they found the coefficient of friction wasn't exactly the correct factor to use when calculating a car's maximum acceleration.
Bill
Bill
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Verdad Gallardo
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Ok. I think what the op is asking is what can be expected of these without excessive wheel spin on launch. He's not asking how to build a watch, he just wants to know an AVERAGE time. Therefore: AVERAGE launch, air temp, DA, ect, track prep=10.9. Just like GM says. No big mystery here.
Le Mans Master
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From: Redmond WA
Under your rules the time would be fairly long. You need some tire spin to get max acceleration. The tires have to slip somewhere around 17% to get max traction. They found this out at the dawn of timed drag racing when cars were going through the quarter mile with ETs that were less than theoretically possible. That was when they found the coefficient of friction wasn't exactly the correct factor to use when calculating a car's maximum acceleration.
Bill
Bill
I think what you're actually saying is the tires need to be rotating about 17% faster than the car is actually travelling, so it sort of holds the car between static and dynamic friction.
But how do we distinguish it from so much other racer lore that's total BS (like coolant travelling too fast to cool itself) that come out of those guys? They're all about results without really sometimes understanding the WHY part, so they're often right in their observations but wrong in their conclusions.
This is the closest I managed to find: http://dcsl.gatech.edu/papers/cdc99a.pdf
Most of what's true for drag strip acceleration would also be true for ABS system deceleration; imagine a system that could HOLD the tire at a speed 17% slower than the car is currently travelling, for example... theoretically perfect braking! Do road course racers ever get into threshold braking where they're doing that but don't realize it, I wonder?
Last edited by davepl; Dec 16, 2016 at 12:25 PM.
Burning Brakes
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From: Scottsdale Arizona
Under your rules the time would be fairly long. You need some tire spin to get max acceleration. The tires have to slip somewhere around 17% to get max traction. They found this out at the dawn of timed drag racing when cars were going through the quarter mile with ETs that were less than theoretically possible. That was when they found the coefficient of friction wasn't exactly the correct factor to use when calculating a car's maximum acceleration.
Bill
Bill
One of the main reason's a Tesla launches quicker than ANY street car in the world from 0-30mph is because traction is computer controlled down to the micro second. They don't even squeal the tires, they just hook and go.
Le Mans Master
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From: Redmond WA
I don't want to get into a whole pedantic lecture on it, but when you see what you -think- is a perfect hookup in NHRA the tires are still actually spinning, just very slightly.
In the "olden" days of the 60s they'd haze them down the whole track, which wasn't nearly as effective. But being just above the slip threshold applies more force than being perfectly connected to the ground.