[quote]Originally posted by sportscoach13:
|Originally posted by mike_m:
[qb]Amazing how the act of sliding down a hill on two sticks can generate such passion!
Some folks suggest that carving involves nothing but rolling the skis onto their edges and riding them--with no additional input as to direction. It would seem then that a carved turn can only be the one arc determined by the sidecut of the skis--exactly the same turn every time--and the skier is simply along for the ride. Obviously this is not so. World Cup skiers carve superb turns. Are they all identical radii? If not, and the racers are not steering their skis by directing the tips of their skis where they want to go, what accounts for the difference in the turns they make?
I'm pretty new and don't pretend to know much, but I'm sure all these race gates aren't the same distance apart and all the World Cup skiers aren't using skis with the exact same sidecut to make the exact same radius turns, time and time again. It's pretty clear that there's more going on than just tipping and riding. The difference is you, and many others here, know what else is going on, and I'm still trying to figure it out. [img]smile.gif[/img] If someone would step up and tell me, in plain English, what exactly else is going on in these turns, I'd be grateful.
Good questions and observations coach, I can see you've been doing some thinking this summer.
A racer/skier can vary carved turn radius. As others have already said a ski is not limited to one carving radius. Turns can be carved at any variation between a straight line and the minimum radius limit of the skis sidecut.
How? Simple, edge angle. When a ski is put on edge (when no pressure is being applied) the center of the ski loses contact with the snow because of the sidecut. The larger the sidecut the larger the space between the snow and the edge. When pressure is then applied to the ski it will bend until the middle of the ski makes contact with the snow. The resulting bend in the ski is what is responsible for the specific shape of the carved turn, the more bend the tighter (smaller radius) the resulting turn.
So the key is to controlling the shape of the carve is to control the amount of bend in the ski. How do we do that? Again, in principle, easy. The higher we put a ski on edge, the more space between the snow and the center of the ski occurs, so the more the ski must be bent to reestablish edge contact with the snow. Also as the edge angle is increased the direction of bend becomes more horizontal (parallel to the snow) so the ski must bend more before the edge finds a base of support on the snow.
To summarize, increasing edge angle does two things that affect turn shape; it increases the amount of space under the center of the ski, and it changes the angle of bend. Both of these tighten the arc.
Other things that affect turn shape are the hardness of the snow, pressure distribution, and speed of the turn.
Soft snow will require more compacting of the snow before sufficient base of support for turn force resistance is achieved. This means more ski bend and a smaller turn radius than would be created by a similar edge angle on hard snow.
The pressure distribution we employ also plays a role in turn shape. Each turn will create specific forces that must be resisted. If balance is directed predominantly to one foot then all the forces will be directed to that foot and the ski under that foot will bend accordingly. If balance is distributed equally over both feet then each ski only resists half the forces and will therefore bend less. This results in a larger radius turn for a similar edge angle.
Finally, something we do not have control over that has an influence of turn shape: speed. The greater our speed, the greater the forces created, the greater the pressure that will be applied to the ski, and the more the ski will bend. Translation; the steeper the hill, the smaller the turn radius that results from a specific edge angle.
Hope that helps some.[ July 11, 2003, 09:05 PM: Message edited by: FastMan ]