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J turn

post #1 of 9
Thread Starter 

From a straight run, how far can you travel back up the hill?

We have a contest coming up and I am wondering if there is an advantage to carving a longer or shorter arc in order to travel the farthest back up hill...

Greg 

post #2 of 9
Quote:
Originally Posted by GR8TRN View Post

From a straight run, how far can you travel back up the hill?

We have a contest coming up and I am wondering if there is an advantage to carving a longer or shorter arc in order to travel the farthest back up hill...

Greg 

The travel in an arc beyond the normal limits of a turn would be dependent on the speed carried into the arc as well as the means of maintaining the speed within the arc. The longer the time spent in the fall line arc, the greater the speed maintained or increased. The shorter the time spent across the fall line or arcing uphill the less the loss of inertia and speed. Also the more precise the carved arc, the less forward speed loss to sideways slipping or skidding. 

So if you can vary your arc radius to maximize the speed which you generate by gravity and then decrease the time spent when gravity is exerting its slowing effect, you should be able to make a complete 360 degree turn, given the right terrain pitch and snow conditions. 

post #3 of 9
Thread Starter 

gcarlson,

  • what i got from you, clean arc vs. loosing forward momentum when the skis skip or slide.
  • less actual time spent in the time when gravity is slowing the momentum (across the fall line?)

my goal is to go back up hill as far as possible, not to ski a 360 degree turn. If I spend less time across the fall line, that would be a shorter radius arc. Wouldn't I loose momentum if the arc is too short by increasing the centripital force that pulls me down the fall line?

THANKS,

Greg

post #4 of 9
Quote:
Originally Posted by GR8TRN View Post

gcarlson,

  • what i got from you, clean arc vs. loosing forward momentum when the skis skip or slide.
  • less actual time spent in the time when gravity is slowing the momentum (across the fall line?)

my goal is to go back up hill as far as possible, not to ski a 360 degree turn. If I spend less time across the fall line, that would be a shorter radius arc. Wouldn't I loose momentum if the arc is too short by increasing the centripital force that pulls me down the fall line?

THANKS,

Greg

 

I would think that one would have to balance the time spent perpendicular to  the fall line when gravity is no longer increasing speed to the radius of the arc which determines how long you remain in this line before actually turning up the slope where gravity is slowing you. Centripetal force equals mass x velocity squared divided by the radius of the turn. So that doubling the velocity would require 4 times the centripetal force to keep the motion in a circle. A reduction in the radius would also increase the centripetal force. Since the centripetal force is provided by the friction or edging of our skis the increase in speed and/or the decreased radius of the turn could lead to a loss of grip with slipping or skidding. I would think that this would be the limiting factor and determine how to balance the speed versus the turn radius to keep the skis moving forward in a clean carved arc. But the less time you spend in an arc which is not profiting from gravity for additional speed until you get to a flat ski moving uphill against gravity should give you the best chance for maintaining speed and distance until you stop. 

 

 

There are certainly other considerations such as snow conditions, proper waxing, turn radius of the skis, etc. It would be interesting to make some test runs and let us know how the forces treat you and what the ideal turn radius vs. speed gives you. 

 

 

post #5 of 9

Keep it simple.  Turn up as sharp as you can while maintaining a pure arc.  Any slip = loss of energy.  Don't worry about "bruising the snow", just try and keep it cleanly carving.

post #6 of 9
Thread Starter 

KISS got it.

tried it today and the clearner the better, can't go very far up hill anyway:( 

post #7 of 9

By turning to sharp, by way of physics, you will loose inirtia, and turning to slowly you will lose as well cause all your momentum will be lost when you traverse the hill.

You, in theory, would want to find the perfect arc that works best to keep your foward momentum a constant untill you start going up hill.

I'm sure there is some mathamatical formula for this. haha.

 

These guys are giving you the right idea all the way. Carve it clean and go for it.

post #8 of 9

The more speed you can work up on the way down and carry around the turn, the higher you will go.  Watch out that you don't get taken out by someone bombing down the hill behind you.

post #9 of 9
Thread Starter 

Sounds good, we will have a closed course. Fingers crossed, not happening til Feb 15th.

Speed, clear arc, get 'er done. Got it.

Cheers 

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