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Discussion Starter #1
I'm asking this mostly due to having ice raced yesterday on a frozen lake, but I'm sure it applies also to slippy wet gravel and snowy roads. First season doing loose-surface racing, so it's a constant learning process, bear with me.

I was in several situations where, driving my AWD turbo GC Impreza on street studded tires, I would exit a corner, be pointed in the right direction, but still have some sideways slip angle, but assume a straight after the corner. So I am able to accelerate hard until the next element. I have found that trying to keep the slide contained/minimized can often be faster, so assume a shallow slip angle.

In a case like this, with very low grip, is it faster to get on the throttle as much as possible and spin/slip the tires while accelerating, or is it faster/better to modulate the throttle to spin the tires less, and try to be nearer to the 'friction point' of the tires? (Not spinning/slipping versus normal grip driving), and then once they hook up, accelerate hard?

What are your thoughts?
 

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don't cut
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Dr. Robert Woods, professor of mechanical engineering at UTA, head of the student SAE program there and accomplished Solo driver, teaches the friction circle, i.e., staying in the limits of traction. Of course, I don't think he has come up with a mathematical explanation for sprint cars.
 

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Discussion Starter #3
That applies more so to tarmac/grip driving though does it not, in our cases we're usually cornering on more kinetic friction versus static friction, no?
 

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don't cut
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According to Dr. Bob, it applies to all surfaces. Here is an article about him from last year: http://www.uta.edu/news/releases/2013/02/sae-triplee-award-woods.php

If you look him up on the University of Texas, Arlington web site, you can find an e-mail address for him. He might be able to answer your question with more authority than I can. I have gone to a few of his seminars and am still not sure about it.

From personal observation while watching Tom French race a SAAB 900 at a local dirt track, it seems with the low power in the 4 cylinder sedan class, driving the "racing line" versus trying to swing the tail out like a sprint car, was faster. The reason I think is that the Pintos, a common car in that class, did not have the horsepower to weight ratio to overcome the braking affect of having the rear tires sideways to the direction of travel.
 

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Whatever gives you the highest average mph over a set distance :p

I'm guessing it can go either way, case in point, Petter Solberg in World RX. Clearly more sideways than most, sliding constantly.

It seems harder on the car, but he seems to be faster than everyone else.

Loeb on the other hand kicks ass at being a minimalist, and has always done well when precision is required.

I think its a fine line. I know that I can accelerate faster in the STi rallycar on studs on winter roads by keeping wheelspin down by keeping the car in a sane gear (like 4th or 5th) rather than spinning it to the moon in 2nd and 3rd.

I also find less shifting on ice teaches you that patience thing people preach about. If you focus on better driving, rather than if you are in the right gear/going fast enough, the speed comes naturally. Again, especially on ice, driving lower in the power band may be ideal for the low grip levels. Even my stock RS can overpower studs on pure ice no problemo. At that point, its all about traction management as you don't have the "mechanical" grip that comes from a car normally digging into the surface (like gravel).

And finally, after driving my civic around lately, sliding the car on pure ice is DEFINITELY not faster as there is too little forward driving force/traction. YMMV.
 

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Discussion Starter #7
Thanks for your input guys.

I'm doing pretty well so far, I've got the patience down on the ice and am either 1st or 2nd in my class at the all the RallyX events I've done.
HiTemp, any chance you're running at the Calgary Sports Car Club Ice Dice series this year? I may need to pick your brain about these kinds of things in person, if you are :D

It does make sense to try and have the tires hook up and not have wheelspin go crazy; since we all know, wheels spinning provide less grip. I just wasn't sure if this would apply also in the really slippery conditions where your lateral momentum is also a consideration, and part of your friction circle is naturally resisting that sideways force.

At least on the most course we did, which was a mid speed long sweeping turn kind of setup, I generally left it in 3rd for everything except the tighter corners, where a bit more throttle response was needed mid-corner to keep the car orienting how I wanted it. So I agree with you there, less shifting can be rewarding.
 

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I may need to pick your brain about these kinds of things in person, if you are :D
Probably won't be at any of the Calgary ones. You should talk to Johnny Summers, he's been instructing a long time. I'm faster than him (you can tell him I said that ;) ) but I'm sure he'll be more than helpful lol.
 

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Discussion Starter #10
Yeah I've spoken to Johnny, he was at the last ice race, I've known him for a while. He couldn't give me any solid answers (or weaknesses) in my driving technique, so I guess it's just all seat time and experience now. I came in 2nd just behind him for overall time at the last race. So things to learn, but not starting from scratch :)
 

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i wanna go fast.
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I'm not sure if this helps the conversation, but in college I asked a similar question. Why slide a car in rally, when clearly there is less traction while sliding? The answer from was this: "In off-road racing, the driving slides the car because the grip is constant. Instead of worrying about which moments he is about to lose traction in an unpredictable way, he slides the car, so this friction is constant, allowing him attack the cornering and be in control the whole time" I summed that up, but you get the point.

Instead of worrying about breaking loose, which can be very hard to do on slippery surfaces, his theory was to just do the whole race at a constant kinetic friction level, and be consistent. Food for thought, not sure if that helps!
 

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I'm not sure if this helps the conversation, but in college I asked a similar question. Why slide a car in rally, when clearly there is less traction while sliding? The answer from was this: "In off-road racing, the driving slides the car because the grip is constant. Instead of worrying about which moments he is about to lose traction in an unpredictable way, he slides the car, so this friction is constant, allowing him attack the cornering and be in control the whole time" I summed that up, but you get the point.

Instead of worrying about breaking loose, which can be very hard to do on slippery surfaces, his theory was to just do the whole race at a constant kinetic friction level, and be consistent. Food for thought, not sure if that helps!
Just don't try to use this as the excuse for why you were sideways in the snow when you see the blue lights behind you...trust me.
 

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No one mentioned slip angles of the tires. Some tires are manufactured with more slip than others. For example a dirt track car has optimum grip at 40º+ of slip angle, a road racing saloon car about 6-8º and an F1 car at about 2º.
 
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