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Launched in the air by the carve - Page 2

post #31 of 44
post #32 of 44
Thread Starter 
Whoa
post #33 of 44
Great video!! just want to point out the "Pole Vault" scinerio here. If you watch he first gets back, and because of this the quad muscle is firing on all cylinders. With that muscle firing like that there is no way to relax the leg and allow the body to pass over the ski. So what you end up with is an inflexible leg. Because of this, as the pressure builds the leg becomes a pole. And the center of mass begins to come across the ski in an upward direction. This hill is steep and it does not take much of this upward movement to come completely off the snow.

"So what we got here... is failure to communicate" ifnn ya hangs on too long you gonna get flung up cause dat leg is just a pole a flingin ya on down da hill.
post #34 of 44
Ski is also a diving board. If the leg doesn't flex to soak up the spring-back, up you go.
post #35 of 44
Well hang on a minute, The ski holds some potential energy when it is all flexed up. However ask yourself how much potential is there? Flexing a ski in a shop does it take 10, 15, 20, pounds of pressure to flex a ski? So the only diving board effect will be exactly that much. So yes there is some but relative to 200 pound skier changing direction at a high rate of speed, and the forces involved in that activity I would say it would be less than 1 percent of the total weight at that particular moment.

I would say that more attention be paid to what we are doing, how fast we are going and how steep the hill is, as larger contributors to the "rebound" formula.
post #36 of 44
Thread Starter 
Quote:
Originally Posted by mosh View Post
Well hang on a minute, The ski holds some potential energy when it is all flexed up. However ask yourself how much potential is there? Flexing a ski in a shop does it take 10, 15, 20, pounds of pressure to flex a ski? So the only diving board effect will be exactly that much. So yes there is some but relative to 200 pound skier changing direction at a high rate of speed, and the forces involved in that activity I would say it would be less than 1 percent of the total weight at that particular moment.

I would say that more attention be paid to what we are doing, how fast we are going and how steep the hill is, as larger contributors to the "rebound" formula.
Maybe all that techno electronic gadgetry in my Head skis are acting like some bionic launch pad for me.
post #37 of 44
Yes you do have to pay attention to what you are doing. For example if you are in a 2 g turn and all your weight is on your heels with your tips off the snow, you've got about 400 lbs of force pushing back and the turn going to end. Release the turn suddenly and you are no longer being pushed inside the turn. If you're above the ski you are being pushed up with a force equal to twice your weight. It's also a question of impact. Jump on a spring with all your weight and you bounce back.
post #38 of 44
I did some experiments in my garage and the small amount of flex we see in the typical race video isn't enough to bounce a skier into the air. I'm too lazy to work out the physics, but I'm guessing the virtual bump is mainly from the release of the forces built up during the turn.
post #39 of 44

Pilot

Quote:
Originally Posted by Richie-Rich View Post
....about my yet to be used RD SL skis and their potential to launch me across the trail.
Wellcome aboard Head SL RD 166.... ready for take off....

http://sports.topeverything.com/defa...tent&ID=F4+478

...thank you for flying Head .

T
post #40 of 44
Clearly, there are two mechanisms at work here.
One is using the leg as a pole vault. The other is like the spring-back from a cars suspension after making an abrupt sharp turn.
post #41 of 44
Quote:
Originally Posted by mosh View Post
Well hang on a minute, The ski holds some potential energy when it is all flexed up. However ask yourself how much potential is there? Flexing a ski in a shop does it take 10, 15, 20, pounds of pressure to flex a ski? So the only diving board effect will be exactly that much. So yes there is some but relative to 200 pound skier changing direction at a high rate of speed, and the forces involved in that activity I would say it would be less than 1 percent of the total weight at that particular moment.

I would say that more attention be paid to what we are doing, how fast we are going and how steep the hill is, as larger contributors to the "rebound" formula.

Mosh,

With all respect, a ski can be bent in the shop with 20 lbs of force, but that does not mean the spring has bottomed out and that's all the ski has got.....

The ski will continue to bend and store energy, but it takes much more force than you can apply just hand flexing the ski in the shop. Hand flexing in the shop only stored that much energy. A 200 lb skier pulling a couple of G's will store a lot more than 20 lbs of force applied in the shop. .
post #42 of 44
Quote:
Originally Posted by Richie-Rich View Post
I was just thinking about the strengthening I still have to do for this coming season and about my yet to be used RD SL skis and their potential to launch me across the trail.

How many of you have entered a high-G turn only to have your edges engage so forcefully that you have been launched airborn out of the turn?

Admittedly my form leaves much to improvement, and it has happened several times to me, so at times now I do put the brakes on.
Back to the original Q.....

The answere is no! The skis will not launch you across the hill or into the air. If your skis are FIS approved 166cm Head SL RD sandwich construction racing skis they will feel like a pair of rr-road tracks. Stiff, heavy and super rigid. Base tuning is imperative. If the skis are new you dont need to take them to a shop and get the base bevel fixed to 0.5deg but if they are used you need to do that. Base 0,5deg/side 87deg. If you tune the skis properly and mount the binding forward of the centermark by 30mm you will have a ski that holds the carve no matter how fast you go no matter what kind of surface. At least it will feel that way when you try them out for the first time. In a while you will get used to them and you will be able to push their limits.
post #43 of 44
Big E
I respectfuly disagree, Potential energy is just that. If it takes 20 pounds that is all that ski can return to you. The rest comes from somewhere else, not the ski itself. Now when you are experiencing the pole vault that 20 pounds of force can create a rotation to the lanunching sequence at a very bad time just as you leave the snow. It could be we give lots of credit to the ski because of the timing of the release of this energy. However it is basic physics. The ski simply can not do to you what your leg can.
post #44 of 44
Quote:
Originally Posted by mosh View Post
Big E
I respectfuly disagree, Potential energy is just that. If it takes 20 pounds that is all that ski can return to you. The rest comes from somewhere else, not the ski itself. Now when you are experiencing the pole vault that 20 pounds of force can create a rotation to the lanunching sequence at a very bad time just as you leave the snow. It could be we give lots of credit to the ski because of the timing of the release of this energy. However it is basic physics. The ski simply can not do to you what your leg can.
I'm in agreement with Mosh here. Out in my garage I bent a ski to the same amount we typically see in the pics of racers. It didn't take much weight and the rebound from that amount of bend was trivial.
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