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Like Turning a Car

post #1 of 12
Thread Starter 
I hear this a lot on this forum. Here are some facts about it.

When you turn your car the outside wheel doesn't turn as many degrees as the inside because it needs to travel a larger radius. This is called "toe out on turns". How does this apply to skiing? Think RR track turns. Parallel shins and equal edge angles? The more vertical seperation(higher edge angle) the farther apart the tracks are, the greater the difference in radiis. Hmmmm?

Most cars built since 1970 use positive caster in their front end alignment. This means that when the wheels are turned the tires tip to their inside edges slightly. Does this apply to skiing? Not in the same way, but it happens.

Cars also have "steering axis INCLINATION". This causes the steering to recenter from a turn. Not the same as inclination in skiing other than that there are no angles between the ball joints or kingpins.

Cars don't "bank" turns. They race on a "banked" track. The reason for the banks is because cars tend to lean to the outside of a turn when their center of gravity(not the same as the center of mass)acts as a lever against the roll center of the suspension.(if the CG was below the roll center the car would bank into the turn like a boat) To my knowledge no one has been able to design a car with the CG below the roll center.
Does this have anything to do with skiing? Probably not much. :

[ August 07, 2003, 10:39 PM: Message edited by: SLATZ ]
post #2 of 12
Cars also can have negative camber, meaning the cars are "canted" onto the inside edges of their wheels.
post #3 of 12
I'm glad someone brought this up. I have a more basic question. I've seen comments that carving is akin to turning a car in control and that you don't want to skid your skiing turns, just as you don't want your car to skid when turning. This is certainly true of normal driving and of F1. However, why do rally drivers turn a lot by skidding? Just curious if there's any equivalent in skiing.
post #4 of 12

I was watching sprint cars and off road trucks on the "telly" last night. I guess I would suggest they skid because they have no choice and in addition that the skid is a constant battle to re-establih cohesion.
post #5 of 12
Thread Starter 
Just like in Skiing, it's a trade off. While the ideal would be no skid, it almost never happens that way. Rallying and dirt racing are probably more like mogul skiing.

Negative camber on a car increases stability because the tires are on their inside edges. This has the effect of keeping the car inbetween the tires.
The equivalent in skiing is negative cant so the skier stands somewhat knock kneed(the shins have the negative camber) A skier on their inside edges has their knee outside of the line of force from the CM to the edge. This requires a lot more strengh and isn't as stable.(the shins have positive camber)
post #6 of 12
just a note, negative camber in cars is also normal because as the car is loaded it will become closer to neutral.
post #7 of 12
Thread Starter 
That depends on the design of the suspension. With Mcpherson struts, like most cars use now, it doesn't change much but often becomes more negative.

[ August 08, 2003, 09:56 AM: Message edited by: SLATZ ]
post #8 of 12
Interesting. In a very basic sense, minus all of the alignment details, I could not agree more. Carving a turn while initiating the tips is so similiar to setting the front end up coming into a turn while driving. Gradually as you enter the weight shifts slowly through the ski towards the rear where you accelerate/snap the tails into the next. As in the car, the weight shifts from front to back as the disposition goes from braking gradually towards acclerating out of the turn. The reward for nailing the perfect line in both disciplines is as rewarding. It's all about the "line", right?
post #9 of 12
Thread Starter 
Hadn't thought of the front to rear thing. But then, other than the trip up the New Glarus hill in May, I've been driving a FWD car. As a SPEED channel commentator said about an Alfa in a British Touring Car event,"the back wheels just keep the exhaust from dragging".
post #10 of 12
Humorous blast from the past on this topic!
post #11 of 12
As for the carving vs. skidding.

Either a a car or skis can "carve" a turn with minimal slippage.

Either can "skid" with the tail hanging out.

Either can "drift" with equal drift at front/rear or tip tail.

Short of the pure carve, the drift is both fast and smooth in a high performance car and in high performance skiing. A high skill alternative to skidding.

FYI the rally cars use the tail around skid to attack corners that would have to be taken too slow to carve. They skid the tail around as soon as possible to align the car with the next straight so they can then use the tremendous acceleration they have avaliable to make up for the slowing for each corner. In skiing we can do the braking , but have fixed acceleration avaliable, so smoother conservation of momentum thru an arc is more efficient.
post #12 of 12
Arcmeister, your last paragraph in particular makes a lot of sense. I hadn't thought of that - just like a lot of very good ideas, it is blindingly obvious only once someone states it. Thanks - I can now throw skidding out the window with no regrets. Oh, or of course I could buy some micro jet engines to attach to the heel piece of my bindings.
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