DH turn shape.

[Speeder]

Is it fair to say that most turns made in a downhill are semi circular ie constant radius versus more "C" shaped ie semi elliptical in the tech events?

 

[pchewn]

I think that the shape of the "ideal" turn in all ski racing events is approximately a cycloid. In each event, the parameters of the cycloid will be different because the speed, offset, and distance between gates varies.

Actual ski turns will deviate from the cycloid because skiers and snow surfaces are not perfect.

Here's an article that describes the cycloid ski race turning shape:

x = -(cp - sin cp), y = -, (1 - cos cp). 2g' 2g (T9.7) This is the parametric equation of a cycloid,


https://link.springer.com/chapter/10.1007/978-1-4757-4345-6_19


I'm quite sure that in no events is the shape of the "best" turn a constant radius.....

 

[Doug Briggs]

The primary consideration of turn size and shape is to get you where you want to be for the next turn. The turn shape is determined by the direction change required to get there. An ideal turn might be perfect, circular arcs, but at over 60 mph, you take what you can get.

As important as shape is pressure on the snow: where it is applied in the turn and whether it is applied smoothly during its buildup and reduction.

 

[oldschoolskier]

DH turns are about conserving energy (the more you have the faster you go) while just changing enough direction to stay on course. Because of the forces involved while there is an ideal turn shape, maintaining speed while staying on course takes preference.

 

[ejj]

I'd say the shape of "fast" has changed over the years--in all events.