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Originally Posted by
michaelA 
Rick,
By the way you're now using the paired-up term "Steering/Skid Angle" you seem now to be acknowledging that the two terms are actually interchangeable as the same thing and that there really isn't any difference... (I could certainly live with that and personally, I like the term 'Drift Angle' as well)
For the most part they are, in terms of what the angle of the ski compared to the direction of skier movement looks like. I define that angle as created under foot, and Ron seems to also when he says, "
the middle of the ski does the work of changing your direction of travel, largely due to its steering angle there."
Where I differ in my use of the skid angle term is that I don't move my point of reference when we get into carving. I still focus on what's happening underfoot, and how much skid the ski is producing. In the case of carving that skid angle obviously would be zero. Ron also looks at steering angles in the forebody of the ski caused by the ski's "self steering effect". While he's perfectly accurate in his explanation of that "effect", the multiple reference points for his steering angle term adds a bit of complexity that I'm able and happy to avoid.
My linking of the two terms was from the context of his under foot focus, and with the purpose of pointing out how our concepts of the primary applications of those skid/steer angles differ.
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I don't believe for a minute Ron LeMaster envisioned any of the "radius limitations" you interpret from his text. I suspect he was writing that material in a particular context and by printing isolated snippets here you're creating a false impression for what he was actually trying to communicate. Since it's obvious to all of us here that edge-angle combined with Steering Angle can result in many different actual turn-radius outcomes, I suspect Ron probably knows it also and that it wouldn't be new information to him.
Actually, Michael, all the way through his explanation, which only constitutes a couple pages, he consistently has a theme of linking steering angle to resultant radius. No where does he really discuss options for delinking the two, or even that such options exist. Whether or not he understands this, we can only speculate what lurks in his head, because it does not live in the book. Like you, I too suspect he's aware of it, but does that really matter? At this point all we can do is deal with and compare to what he has put in print.
And really, Ron LeMaster and his beliefs are not what this thread is about. He simply came up because a term exists that's very close in nature to one I use, and we needed a definition of it so I could explain why I chose not to go with it.
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As I see it, turn radius is managed by a combination of edge-angle, ILS and pressure. The resulting Steering/Skidding Angle is just the outcome of those three inputs (along with slope angle, snow conditions and current speed which we don't manage internally). Would you agree with this?
Yes, absoulutely. And it's the options we have to mix and match the amount and nature of the edge, steering and pressure we use that provides us the ablity to greatly delink radius from skid angle.
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Also, when you say, "Any skid angle can be combined with any turn radius"... Wouldn't you agree that this is highly dependent on slope angle and/or speed? For instance, there's no way to maintain a large Steering Angle *and* a large turn radius unless you've a lot of speed or a reasonable slope-angle to keep you going.
Of course. There will be a limit to how flat a slope that an ultra large skid angle will allow you to remain in motion. It does, after all have the potential to produce a large amount of drag, which is the point of it.
It's actually a great training exercise to see how big of an skid angle you can employ on a flat slope,,, super for developing fine edge control, but in reality such a slope is not where a large skid angle is going have it's most useful application. It's designed to provide speed control with in a specific turn shape. On on a steeper pitch it allows students to learn good turn shape within a personal comfort zone. That's where this particular radius/skid combo really shines.
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I would agree that Steering/Skid Angle does figure into the amount of friction (braking) we produce - but so does edge-angle and pressure (again, as modified by slope angle, snow conditions and speed).
It's all part of the equation. Turn shape,,, degree of turn,,, they too are very useful speed managment tools. But they will never touch the versatility and pay back potential of skid angle when it comes to speed management options.
Edited by Rick - 11/7/09 at 11:30am