New Posts  All Forums:Forum Nav:

PMTS Camp at Hood - Page 9

post #241 of 254
Thread Starter 
Quote:
Originally Posted by ssh
Of course not... but that's not really the point, is it?.
I hate to take this thread off topic again, but I'm wondering what the point of PSIMan is (other than being a pretty cool gadget)?
post #242 of 254
Thread Starter 
Quote:
Originally Posted by Powdigger
Anyone . . . Anyone. . . .the ____________ curve . . .




This thread is great
??? What goes in the blank???
post #243 of 254
Quote:
Originally Posted by Max_501
??? What goes in the blank???

Blank? I thought it was a straight line, followed by a curve, but he just didn't know how to draw a curve...
post #244 of 254
Quote:
Originally Posted by Max_501
??? What goes in the blank???
It was a movie reference but I screwed it up. It was a reference to Ferris Buhlers Day Off. I think it is actually goes:

Anyone . . . Anyone (something) ______ doo economics.

Ed

This is the most entertaining thread of the summer.
post #245 of 254
Quote:
Originally Posted by Max_501
I hate to take this thread off topic again, but I'm wondering what the point of PSIMan is (other than being a pretty cool gadget)?
It shows that skiing can be performed without active input and without thinking about it. PSIman is purely mechanical yet it skis. What I like is that the skiing it performs is edge to edge which is what we consider to be good parallel/carving skiing.

A demo by something like PSIman can help people see what they may not when looking at another human. It breaks skiing down to the simplest concepts and forces.

Like all tools, it has its place in the teaching spectrum. A good instructor can use it to advantage.
post #246 of 254
Quote:
Originally Posted by disski
YAY
Thankyou ...
especially the centrepoint/focal point one.... I never got why everyone was so obsessed that both skis were on a circle with the SAME centre.... unless you skied the whole 360degrees out you would be quite happy for their centres to be about ... say... "hip width" away from each other...
Sorry to be late coming into the discussion, but I missed a bunch of it over the weekend. I'm glad someone came back to the concentric circles again, because I was thinking:

I'm not Physicsman, and I'm just visualizing in my little pea brain, but.....It seems that it is possible for both skis to be carving arcs of roughly equal diameter without deliberate adjustment on our part and without convergence due to the facts that 1) we're skiing arcs, not full circles,2) there are two focal points with the focal point of the arcs being approximately hip distance apart, and 3) both focal points continue to move down the hill with the COM.

Could someone correct me if this is faulty thinking???
post #247 of 254
Thread Starter 
Yes, the tracks would look like this:

post #248 of 254
Quote:
Originally Posted by Max_501
Yes, the tracks would look like this:

That would necessitate your inside leg starting behind your outside one (or finishing ahead of it), and you would also have, as demonstrated by the drawing, the width of the gap between your skis varying around the turn, BUT... for both arcs to be of the same radius would require the skis to be on top of each other at the start and end of the turn - if you were to expand that drawing to include the horizontal part, the two circles must overlap there, otherwise their centres are not in the same horizontal plane, and so they physically can't be the same radius (without your legs crossing on the way out of the turn )
post #249 of 254
Isn't that graphic drawn with two stationary focal points? Wouldn't the focal points continue moving down the hill with the COM, then change sides prior to the convergence point? how would the moving focii affect the arcs????

(The pea brain is getting strained with all this thinking and visualizing!! )
post #250 of 254
Quote:
Originally Posted by volklgirl
Isn't that graphic drawn with two stationary focal points? Wouldn't the focal points continue moving down the hill with the COM, then change sides prior to the convergence point?

(The pea brain is getting strained with all this thinking and visualizing!! )
The centre points of the arcs would only move down the hill if they weren't arcs (e.g. if you introduce skidding/tipping/twisting/pressure/... into the equation), otherwise it's making a turn based on a fixed radius.
post #251 of 254
Thread Starter 
Quote:
Originally Posted by Bob Barnes/Colorado
--I agree that mastering the "no up" movement through the transition is critically important for expert skiing, and a movement that few skiers have mastered. It's an especially important option to master for shorter turns at speed, and for moguls, and powder, and other challenging terrain and conditions. It's an important skill! But is it a fundamentally and universally important movement? Are there times when it is unnecessary, or even a mistake? You know my answer!
Bob, when is a flex movement to release a mistake?
post #252 of 254
Max, Bob may be referring to what I was when discussing GS movements versus slaom movements a page or two back int he discussion. Often an up movement (cross over) is used to set up the next turn on steep pitches because with a cross under you gain so much speed and can risk getting very late and low. For free skiing it is a good tool to have in case you find yourself in a situation that requires you pull yourself out of the back seat, or that requires you initiate a turn in a very far forward position (possibly on or just before a steep section on a groomer). I am sure Bob can come up with others though.
Later
GREG
post #253 of 254
Quote:
Originally Posted by T-Square
It shows that skiing can be performed without active input and without thinking about it. PSIman is purely mechanical yet it skis. What I like is that the skiing it performs is edge to edge which is what we consider to be good parallel/carving skiing.

A demo by something like PSIman can help people see what they may not when looking at another human. It breaks skiing down to the simplest concepts and forces.

Like all tools, it has its place in the teaching spectrum. A good instructor can use it to advantage.
I video taped it and analyzed it frame by frame like I would one of my racers.
I found out some pretty interesting things.
The parallelagram linkage that is the "hips" has loosness in it. This causes a slight impact as the shield, which contains the CG, crosses and moves forward causing it to tip. The loosness makes it so the skis don't change at the same time. At times it appears to stem but this may be because of the forward swing of the CG brings the outside ski up on it's tip. What happens when it turns is the CG swings forward and over the outside edge of the inside ski. The outside ski is lifted slightly and counterbalances it as it turns on the inside ski (sometimes it tips inside but those parts are edited out). The only reason it works at all is because the CG is well below the carriage parallelagram.
My conclusion is, that while it is an ingenious device (toy?) it has very little to do with a human turning a pair of skis.
post #254 of 254
Quote:
Originally Posted by Wear The Fox Hat
The centre points of the arcs would only move down the hill if they weren't arcs (e.g. if you introduce skidding/tipping/twisting/pressure/... into the equation), otherwise it's making a turn based on a fixed radius.
OK, so you're saying the COM/arc focii is static/stationary during the turn : : : ??. Hmmm.... (scratching head!)
New Posts  All Forums:Forum Nav:
  Return Home
  Back to Forum: Ski Instruction & Coaching