Originally Posted by majortato
The amount of energy stored in a ski is not enough to send a skier cross the hill.
The amount of energy stored in a ski is significant...even if it is not enough to send the skier across the hill, it can send itself across the hill faster. That's all we need! If the ski can go faster, then the skier's COM can take a more aggressive or shorter line....we don't need enough energy to send a 180lb skier across the hill..only enough energy to send a 5lb ski across the hill.
Ok, so how much energy is stored? Make a model and estimate. Did you do the carpet test? Also do you understand that to send something across the hill it needs to fly?
A force perpendicular to the direction of travel is a turning force.
A sustained force applied perpendicular to the direction of travel is a turning force. A force applied to the initial direction of travel is NOT a turning force (think a swimmer going across a river). As a physicist, you of all people should understand this fairly easily.
What I wrote is the definition of a turning force. Don´t know what you are trying to argue.
What is the initial direction of travel? The CoM is basically going down the fall line crossing the center line as it turns. While you are going towards the center line, i.e. after the fall line, you claim that you can increase the speed by pushing. At this time you are basically pushing yourself up the hill. Do you see why this does not makes sense? We are not even using physics here. Common sense.
The external force pressing the ski into the surface is larger than the spring force in most of the turning phase.
The external pressing force happens before the fall line when we pressure the skis. After the fall line, the pressing force decreases and the spring force takes over.
Well you agreed on: "If there is an external force pressing the ski into the surface, the ski "spring" cannot generate an opposite force that is larger than this force. At no point in the turn.
Agreed. It doesn't need to."
This means that the spring force "takes over" a lot later than you think.
If more camber made racers faster skis would have a massive camber.
More camber can add more spring action....it does not necessarily make a skier faster. Don't confuse the two. There is a delicate balance that needs to be achieved.
You are the one claiming that the spring action accelerates the skier out of the turn. If that was true...
Modern race skis have almost no central camber and reverse tip camber.
reverse tip camber is to avoid tips digging into snow...this is obvious. The tip itself doesn't do much on the ski. All modern race skis I own or have owned have some camber.
Lol, you realize we are talking obout racing on ice/firm snow here? Reverse camber in race skis is used because you want the ski tip to be soft but torsionally stiff. This is very difficult to make but with some reverse camber you don´t have to make the tip as thin. The tip of a racing ski is very important.
A spring system in a ski delays pressure input output function.
pressure input happens when you create pressure....it's not related to the ski. How the ski responds to that pressure is a different story.
What? You have been claiming all along that the spring force "takes over", where does the resulting pressure come from if "it´s not related to the ski"
It is possible to accelerate out of a turn by applying muscular force, but not in a direction that increases speed or brings the skier faster to the bottom.
I disagree. This is basically our debate.
So, you are basically claiming that you accelerate out of a turn by pushing muscularly? Well, I claim that in order to accelerate in a desired direction you should apply force above the fall line and minimize it after the fall line.
The ski-snow interface does not care if the force comes from energy stored in the ski or your legs. This means that released energy from the skis after the fall line would have the same effect as pushing after the fall line. Following this argument along with your reasoning then would come to the conclusion that pushing after the fall line is a good thing, and please don´t come with the argument that this happens at the fall-line because we agreed that the release is not instantaneous. In the best of worlds it starts at the fall line, but most often a lot later.