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# the folly of 'fall' - Page 3

Quote:
Originally Posted by fatoldman

L&AirC,

Are you really falling down the hill and falling either right or left or are you continually moving forward and using your skis to drive your body either right or left. I am skiing my best when I feel the most connected to the snow surface. Without this connection I become a ballistic object following an arc that will return me to the surface of the planet. This disconnection can feel like falling but to me it feels like a moment of floating over the snow surface.

fom

Quote:
Originally Posted by fatoldman

L&AirC,

Forward is basically the direction I am moving in at any particular moment. Most of the time I am moving forward along a serese of arcs.

When you ski you are a body in motion. A body in motion travels in a straight line unless acted upon by an outside force which when applied will produce an arced path. If the outside force is removed the body will resume moving in a straight line. So for us to create an arc to the left or right we must apply a constant force. Having a platform off which you can redirect your body will only provide a momentary force, not the constantly applied force needed to produce the arcs that we call turns. I use the skis to generate the force I need to continually apply to the body to move it along an arced path. The forces generated by my skis and gravity are the things that propel me when I ski and gravity only propels me in one direction, down the hill. If I want to go "over there' then I must learn how to use the skis to propel myself 'over there'.

fom

FOM,

Sorry it's taken so long to get back to you on this.  Been busy.

I've thought about this a bit.  Haven't really read many of the other posts since my last post; just skimmed.  Hope I'm not throwing a wrench in the conversation.  Anyway - Yes, I'm falling down the hill.  I control the fall with my skis as a parachutist controls their fall with it's parachute. Wings on a plane, rudder on a boat etc, all controlling the fall through steering.

I also have trouble with the skis "propelling" me.  Gravity propels me.  The skis let me ride gravity like a hanglider rides it.  I understand that there is some propelling coming from a turn but it is minimal.  If it was anymore than that you would be able to skate on a flat into a turn and then start propelling yourself from turn to turn.

Even when you're walking on a flat surface, part of the time you are falling and the proof is that there is a point of no return; you have to keep going forward.  You can stop short but you can't reverse it until you stop first.  Skiing is a series of falls like our steps are.

At least that's how it works in my head.

Ken

Ah we're getting somewhere...

...if the arc is downward (in the ball example), or down the hill (in the case of a ski turn), friction and Gravity do exactly the same thing. If the force acting upon the object pulls it in towards the turn, that is a centripetal force. To bring that back to ski turns, kinetic energy expressed as linear momentum carries the body across the hill after it's released in that direction. Since the feet are released a bit later they turn across the hill more than the body. Thus we have the convergence / divergence of the dual paths. X over / under is largely irrelevent to this since both will produce the same inclinated stance early in the new turn. What's interesting is that Gravity only pulls us downhill, when we turn we change direction relative to the fall line but Gravity alway pulls us down the fall line. In the first half of a ski turn that would be an inward pull. Rendering the strong edge and pressure moves a bit superfluous.

Quote:
Originally Posted by justanotherskipro

Ah we're getting somewhere...

...if the arc is downward (in the ball example), or down the hill (in the case of a ski turn), friction and Gravity do exactly the same thing. If the force acting upon the object pulls it in towards the turn, that is a centripetal force. To bring that back to ski turns, kinetic energy expressed as linear momentum carries the body across the hill after it's released in that direction. Since the feet are released a bit later they turn across the hill more than the body. Thus we have the convergence / divergence of the dual paths. X over / under is largely irrelevent to this since both will produce the same inclinated stance early in the new turn. What's interesting is that Gravity only pulls us downhill, when we turn we change direction relative to the fall line but Gravity alway pulls us down the fall line. In the first half of a ski turn that would be an inward pull. Rendering the strong edge and pressure moves a bit superfluous.

Are you arguing that gravity pulls us down the hill? I don't think anybody would disagree with that. Agreed the convergence and divergence of the dual paths is largely irrelevant to the discussion.

So, what do we have at our disposal to resist the pull of gravity?

Answer: "strong edge and pressure moves". which are exerted, not down the hill per se , but diagonally into the ground.

Quote:
Originally Posted by justanotherskipro

Ah we're getting somewhere...

...if the arc is downward (in the ball example), or down the hill (in the case of a ski turn), friction and Gravity do exactly the same thing. If the force acting upon the object pulls it in towards the turn, that is a centripetal force. To bring that back to ski turns, kinetic energy expressed as linear momentum carries the body across the hill after it's released in that direction. Since the feet are released a bit later they turn across the hill more than the body. Thus we have the convergence / divergence of the dual paths. X over / under is largely irrelevent to this since both will produce the same inclinated stance early in the new turn. What's interesting is that Gravity only pulls us downhill, when we turn we change direction relative to the fall line but Gravity alway pulls us down the fall line. In the first half of a ski turn that would be an inward pull. Rendering the strong edge and pressure moves a bit superfluous.

JASP,

I'm throwing the flag.

How do they do the same thing?  Friction is gravity's arch nemesis.  What gravity pulls, friction tries to stop or at least slow.  Hence the need to wax skis and the fact we only ski when the mountains are covered with slippery stuff.  Since gravity only pulls down the fall line; not to the side or anywhere but down, the skis use frictions to defy gravity momentarily so we can change direction.  Friction does not pull us in any direction.  At least not that I'm aware of.

I think that is why it is more difficult to do some skiing drills slow.  Until we are using a force that is greater than gravity (I thinks it's 14.7psi), gravity is winning or at least has greater control.  When we exceed gravity's force with a stronger one, we now have the upper hand.

I may be reading more in to this than you intended but it caught me attention.

Ken

L&AirC,

Let me approach this from a different angle. It is quite common for me to go from 20 mph in one direction to 20 mph in the opposite direction in a second (we call this a short turn). This gives us a net acceleration of 40 mph or just under 59 feet per second to account for. Gravity won't work here because; (1) its too weak only 32 fps per second, (2) its vector is in the wrong direction, gravity accelerates us only down toward the center of the earth. So how can i account for the equivalent of almost 2 gravities of acceleration in a direction which gravity won't accelerate me? I just can't account for the observed facts using the concept of falling to get where I want to go.

There are two sources of force i can use here. First is the ground reaction force. When I push on the snow (ground) the snow pushes back with an equal force, in other words if I push the world right the world pushes me back to the left. Due to the world having a greater mass than me the observed outcome is that I move strongly to the left and the world moves just a little tiny bit to the right (let's not confuse things here by bring up frames of reference). Second is the force generated by the ski itself. A ski, decambered/edge engaged/traveling forward over the snow, generates a force that can be expressed as a vector perpendicular to the surface of the ski pushing on the sole of our foot. With these two forces acting on the sole of my feet all I have to do is to align my com in such a way as to allow this force to push it where I want it to go. In other words when I ski I am pushed around by my feet.

fom

PS To pour ink into already muddy waters gravity isn't what accelerates us down the hill its the ground reaction force.

Ironically: In the interest of achieving ever more minute accuracy of understanding, this discussion has become completely useless to our students.

Quote:
Originally Posted by fatoldman

L&AirC,

Let me approach this from a different angle. It is quite common for me to go from 20 mph in one direction to 20 mph in the opposite direction in a second (we call this a short turn). This gives us a net acceleration of 40 mph or just under 59 feet per second to account for. Gravity won't work here because; (1) its too weak only 32 fps per second, (2) its vector is in the wrong direction, gravity accelerates us only down toward the center of the earth. So how can i account for the equivalent of almost 2 gravities of acceleration in a direction which gravity won't accelerate me? I just can't account for the observed facts using the concept of falling to get where I want to go.

There are two sources of force i can use here. First is the ground reaction force. When I push on the snow (ground) the snow pushes back with an equal force, in other words if I push the world right the world pushes me back to the left. Due to the world having a greater mass than me the observed outcome is that I move strongly to the left and the world moves just a little tiny bit to the right (let's not confuse things here by bring up frames of reference). Second is the force generated by the ski itself. A ski, decambered/edge engaged/traveling forward over the snow, generates a force that can be expressed as a vector perpendicular to the surface of the ski pushing on the sole of our foot. With these two forces acting on the sole of my feet all I have to do is to align my com in such a way as to allow this force to push it where I want it to go. In other words when I ski I am pushed around by my feet.

fom

PS To pour ink into already muddy waters gravity isn't what accelerates us down the hill its the ground reaction force.

The part in bold.  I think this is what I'm getting hung up on.  "It" doesn't do squat by itself.  I make it do everything (I think everything).  Without my weight and guidance, it might slide down the hill (if I remove the brake) and will continue down the fall line only possibly changing direction if friction gets in the way.  Decamber and edge a ski without a person attached and I think it will just lay there.

I'm starting to drink the ink and have a couple thoughts on this.  I might be getting hung up on terminology but....

The reason we start sliding down hill is because of gravity.  We gain speed and make a turn by using the forces present to our advantage by manipulating our skis.  If each action has an "equal" and opposite reaction (as you described above) we can't accelerate unless we get an assist from something else.  In skiing, that would be gravity.

I'm sure it's been debated here before but my head is a little fried from coming out of the attic to put some flooring in (good thing I waited until it got hot out), but which goes faster, someone skiing a straight line down the fall line or someone making turns down the fall line?  The straight liner will get there quicker but that is probably from covering less distance.

Then carry these thoughts over to the comments about skating then turning on the flats.  No gravity so you have to use muscles to move.  Now the reaction forces can't accelerate me because there isn't a gravity nudge in the fall line.

By the way, though I keep getting distracted by life, I find this thread/debate very helpful.

Ken

Quote:
Originally Posted by nolo

Ironically: In the interest of achieving ever more minute accuracy of understanding, this discussion has become completely useless to our students.

The saving grace will be if we understand it from every angle, we will have a larger tool box of knowledge to draw from to answer their questions and /or describe things to them to help them ski better.

Maybe. I'm a big fan of simplicity in teaching. You don't need to know the actual physics to ski well.

Quote:
Originally Posted by nolo

Maybe. I'm a big fan of simplicity in teaching. You don't need to know the actual physics to ski well.

They tend to sort themselves out  by themselves  as long as you consider their effects and use them to your benefit.  I know when  I walk I use many tools to make use of physics but I don't really think much about it

as an edit;  You may want to learn some of it to teach well. Ever taught a Chinese engineer ?  They want to know everything .

Edited by GarryZ - 5/27/12 at 3:20pm
Quote:
Originally Posted by nolo

Maybe. I'm a big fan of simplicity in teaching. You don't need to know the actual physics to ski well.

I don't believe in teaching to this detail.  I do believe in understanding things to my fullest potential.  Some people like to tear the engine apart and see how it's put together, others like to drive without ever understanding anything about the engine past turning the key.

This is of no benefit to the majority of my future students as none of them will have been introduced to physics yet or even what gravity is.  Little kids struggle with the concept of the fall line.

My participation in this thread is about me understanding and on the odd chance an older student has a question specific detailed question, I'll be able to do more than .

Isn't this level of detail exactly what this particular forum is for?  Get down in the nitty gritty detail and wallow around in the physics until your head hurts.  Hopefully the pain stops before ski season starts.

You're absolutely right, L&AirC -- or as one guru puts it, simplicity is on the other side of complexity. Meaning, I think, that a student (meaning you and me) has to muddle through the complexity to get to an understanding that is elegantly simple to share with others. I'm just making cautionary notes -- you'll bore the heck out of your students if you insist that they know the physics before they can go ski.

Quote:
Originally Posted by nolo

You're absolutely right, L&AirC -- or as one guru puts it, simplicity is on the other side of complexity. Meaning, I think, that a student (meaning you and me) has to muddle through the complexity to get to an understanding that is elegantly simple to share with others. I'm just making cautionary notes -- you'll bore the heck out of your students if you insist that they know the physics before they can go ski.

Ditto.  I am the LAST person to explain physics.  I am in the middle of muddle and enjoying it.  Each time I make it to the other side of complexity, I realize there is a whole other level that I hadn't even considered.  Keeps me thinking and is more fun than doing sodoku

Friction and Gravity act the same way as they would with the ball. Although since the ground is inclined the net direction isn't straight down but down the hill. Thought that was obvious but obviously how I wrote that was not clear.

Oisin, Gravity is the primary motive force involved in skiing. Although resisting it is only half the story, as in the second half of the turn where we turn across the hill. The other half is to cooperate with it. As in the first half of the turn, or through the transition phase. Moving towards it doesn't require pushing against something, sometime all we have to do is let it have it's way with us. To expand on that point, Gravity never sleeps and allowing our body to fall into the new turn doesn't imply hitting the snow, just letting it topple far enough for the net result to be an inclined stance and alignment at the beginning of the next shaping phase. That shaping phase can be deliberately moved to any part of the next turn, it's something we teach junior racers who have perfected the round high line and are ready to move onto the next level in racing. WC stars learned this well before getting to that high level of racing. In short they own a wide variety of skills and don't make just one type of turn. They would DNF if they did that. I'm disappointed that you don't seem willing to accept that fact.

Edited by justanotherskipro - 5/27/12 at 3:16pm

Just Another:

I certainly accept that racers benefit from having a variety of turn types, strategies and tactics. just as our students can.  I was only trying to explain one type of turn in which it would appear  that the racer is falling down the hill. Someone advanced the theory that the racer is in fact intentionally doing that with the expectation that he will recover toward the end of the turn. I can accept that that is possible and sometimes done but I don't think it is necessarily a good idea nor is normally what we are seeing in those racing pics. I don't want to nail down the physics, merely explain the racer's movements to clarify what is happening so that we don't go out there and encourage our students to toss themselves down the hill and try to recover. I'm a big fan of lateral learning though and a personal motto in this regard is "never say never". You can't have too many skills and doing it all kinds of ways just builds your toolkit if you can avoid getting hurt.

All sane persons should stop reading at this point but, since the arcane matter of the physics of this particular aspect of a particular type of turn have been raised, I will attempt a simplified and, hopefully understandable, explanation. Goodness knows I've probably messed it up so far.

The force that tends to pull us to the outside of a turn is angular momentum. Anytime a moving body changes direction momentum tends to want to keep us moving in the direction we were formerly moving. In a turn this means that force is is toward the outside of the turn (did I say that already?) Ok, so at any given moment a component of this force resolves itself to varying degree into the feeling we are being pulled to the outside. We resist this force with edging and our legs, by pushing against the grip we've created on the snow. We balance against this normally with an inclined stance. Gravity is pulling us toward the earth as well as our momentum is pulling us outward.The source of momentum and angular momentum is always gravity by the way unless you've got a jet pack or something.

Still with me? I'm getting nauseous at this point.

OK so, in the type of turn we are discussing, the racer has just crossed the fall line and begun a very early crossover with  the result that he is inclined down the hill. This can be way before his skis have turned sufficiently that they are parallel to the fall line remember. So there's the racer seemingly hanging out over space and we wonder why he isn't falling over?  Maybe he is, as someone suggested. The problem for the racer is that at this high early phase of his turn there is not sufficient force pulling him to the outside of the new turn to balance against. Gravity pulling him in a direction down the hill and toward the snow is dominant. So, and here's the nut, a sudden forceful extension of the legs provides, for a tiny moment, a replacement for that force. The direction of that extension is inward (from an outward force) but also upward. Remember, he begins this movement from a very compressed position so a part of the effect, in addition to generating an instant of force against the edge platform, is upward. OK? So he isn't falling down, hoping to catch himself before he hits the snow, but balanced in a somewhat normal manner. Now the effect of this move is only available for an instant because the skier cannot keep on creating this force. Once he's made the extension movement he's given it all he can. But an instant is all that is required since, when his skis reach the fall line and turn beyond it, he starts getting back that normal outward pulling force and he can continue his balancing act in the normal fashion.

I hope this clarifies the matter for those who care. I apologize for any misunderstanding I may have created. Certainly it was not my intention to lead us so far into rocket science (with which I am woefully unfamiliar).

Edited by oisin - 5/27/12 at 7:11pm

Re the early shaping of the turn:

There may be a variety of reasons why a racer might choose to do this. I began playing with this back in the days when slalom skis were long and skinny and bendy.  In order to carve an arc you had to bend the ski. I was trying to carve the entire turn or as much of the turn as I could so I began playing with this early turn shaping by extension in order to bend the ski before the fall line and discovered it also provided something to balance with. Doing this made it possible to carve and shape the very top of the turn. It was kind of fun, making these turns in which the major shaping was established at the top and the rest of the turn, after the fall line was almost anticlimactic.

We have so much very hard snow out here in the East, especially early in the season you sometimes have to make your fun, if what you enjoy is learning and developing. That brings me to another point regarding why this can be useful. The way to ski with the most control on very hard snow (but not blue ice) is often to carve your turns. The way you move and the angles you can make are often far more significant than the sharpness of your edges which you might think was key to control in this kind of stuff. The problem with a carved turn is a vastly reduced frictional resistance so you find that shaping your turn and turning further across the hill is often required in order to keep your speed under control. Often when you see someone carving turns on very hard snow it almost looks as if he were accelerating across the hill at the end of the turn. The problem with loading the skis at this point when they are crossing the fall line is that too much force upon them at this point can cause them to break away and skid so shaping the turn early is a way to avoid this. As your skis cross the fall line you may actually even be skiing uphill slightly in an effort to bring your acceleration down but beginning a move across your skis to release the edges and initiate the next turn.. Really carving feels a lot like ice skating to me: little friction, lots of turn shape.

Its neat to see racers doing this type of turn for what reasons they have.

Oisin, from Wiki...

In physics, angular momentum, moment of momentum, or rotational momentum[1][2] is a vector quantity that can be used to describe the overall state of a physical system. The angular momentum L of a particle with respect to some point of origin is

$\mathbf{L} = \mathbf{r} \times \mathbf{p} = \mathbf{r} \times m\mathbf{v}\, ,$

where r is the particle's position from the origin, p = mv is its linear momentum, and × denotes the cross product.

The angular momentum of a system of particles (e.g. a rigid body) is the sum of angular momenta of the individual particles. For a rigid body rotating around an axis of symmetry (e.g. the blades of a ceiling fan), the angular momentum can be expressed as the product of the body's moment of inertia, I, (i.e. a measure of an object's resistance to changes in its rotation rate) and its angular velocity ω:

$\mathbf{L} = I \boldsymbol{\omega} \, .$

In this way, angular momentum is sometimes described as the rotational analog of linear momentum.

Angular momentum is conserved in a system where there is no net external torque, and its conservation helps explain many diverse phenomena. For example, the increase in rotational speed of a spinning figure skater as the skater's arms are contracted is a consequence of conservation of angular momentum. The very high rotational rates of neutron stars can also be explained in terms of angular momentum conservation. Moreover, angular momentum conservation has numerous applications in physics and engineering (e.g. the gyrocompass).

Don't know why you claim special insight into what type of turn WC racers do most often but that's exactly what you wrote. All I am saying is that is an overstatement. You also claim Ron's work shows this and I've provided more than a few montages from his site that suggest otherwise. They use what they need to use to stay in the course while trying to reach the bottom faster than anyone else. Bode is especially adept at stivoting throught the entire first half of a turn and carving through the second half. He can do so much more than that though. So can the rest of those folks.

BTW, progressive edge and pressure doesn't imply waiting until the last few feet of a turn to engage the edges. At that point we need to be flexing to keep the skis carving. Although I've watched Bode do that very thing. The rest of us don't own his skill set though, so that tactical option isn't always a doable thing.

The topic herein this thread  is falling into the turn. I can do that while carving, or skidding. Ice or no ice it's really not that hard.

Edited by justanotherskipro - 5/28/12 at 6:40pm
Quote:
Originally Posted by GarryZ
Ever taught a Chinese engineer ?

I have. When I got the physics wrong he put my fingers in this devilish tube thing. Now I have to ski with special gloves and hold my poles real close together.

I have never taught a Chinese engineer. I taught an Irish one though. Once we cut through the brogue we went skiing and had a blast.

I'm done talkin' on this topic so I'll leave you fellers to go on dancing on the head of your pin.

So what's left to discuss here? Falling into the turn is only one way to describe the concept of progressively allowing the body to move towards the next turn. If that move is too strong (as in the hucking move previously discussed), then the body moves too far inside the new turn. Thus making balance on the inside edge of the outside ski impossible. A tell tale sign of this is when a skier ends up trying to balance on the little toe edge of the inside ski. If that move is too weak, then the skier must actively do something to get the core further inside the next turn just to gain edge purchase (as in the skidded turns where a stacatto edge set finish is present). Between those two extremes exists a stance that is aligned along what LeMaster and others call the balance axis. From that well balanced stance we can selectively apply any combination of skills to produce any turn. The myth of needing an edge platform established before beginning the new turn (changing direction towards the fall line) has also been discussed and hopefully exposed as dogma based on a incomplete understanding of the math and science.

As further proof I offer the simple Garland drill as proof of the flaws in that sort of thinking. The drill includes direction changes from both active edge releases and re-engagement. In the release phase the skis turn towards the fall line without any edge engagement needed. Why? It's simple, Gravity is pulling them there. In that way Gravity is acting as a Centripetal force since the skis are turning in that direction. Of course in the last half of the turn Gravity is no longer pulling us to the inside of the turn because we have changed direction  but to be clear here, it's not because Gravity has changed directions.We have. In the active edge engagement phase the ski (and our body) turn away from the fall line (across the hill). Additionally it needs to be pointed out that when we release the skis we will immediately begin moving diagonally across and down the hill due to the combined efects of Gravity and our inertial momentum. Obviously the faster we are traveling on that traverse, the longer our momentum will carry us across the hill without any engaged edges and only when we slow down a bit will we begin to turn downhill.

In conclusion I have been suggesting early edge engagement and a strong extension move can hasten that but cannot be considered appropriate for more than one type of turn shape. In that way it's of limited use and inappropriate for the much wider variety of turns we would use in a race course, or out on the rest of the mountain for that matter. IMO, owning a larger variety of movement options and knowing where and when to use them is the best measure of true expertise. When we close our minds to that fact, we limit our skiing performance.

Edited by justanotherskipro - 5/30/12 at 2:42pm

FoM, you seem to imply that an even distriubution of pressure, and in particular in the transition is a good thing, and Oisin you seem to imply that a forceful extension early in the turn is the go to move for racers. I strongly disagree with both of these statements, and I'll explain why I think so.

I apologize in advance for the length of this explanation but I know it has been an epihany for at least some people.

When an edge is engaged in the snow you can divide the force that the edge affects the snow with in two major components.
1. The force component that is tangent to the snow surface. This force is given by the instantaneous turn radius of the CoM. If you are going straight (or free-fall "straight") this component does not exist. If you are doing tight SL turns at WC speeds this force is huge. It is proportional to the square of the speed and inversely proportional to the turn radius of the CoM. This can also be called the centripetal force.
2. The force component perpendicular to the slope. The time average of this component is given by the steepness of the slope and the weight of the skier. If the slope is flat the average is equal to the weight (multiplied with g to be strict).

Now you may have noticed that I used the term "average". The interesting thing about the second component is how it is distributed in time throughout a turn. In a static "park and ride" turn the size of this force is quite constant and proportional to your weight x cosine(slope angle).
On the other side of the spectrum we have a highly dynamic turn, like a WC SL racer that flies through the transition with very little pressure on the skis and has a short by very intense engagement of the edges. Say for example and simplicity that he has no noticable pressure for 2/3 of the turn and that he has a high but constant pressure during 1/3 of the turn. This means that the second force component will be proportional to 3 x weight x cosine(slope angle) during this 1/3 of the turn.
In other words you cannot change the average magnitude of this force, only where it is distributed.

Now if we consider the following facts:
-The steeper it becomes the less is the average of the second force component (due to the cosine(slope angle), if you don't know your trigonometrics you just have to trust me on this one)
-The steeper it becomes the faster we go if we carve
-The faster we go the higher the first force component will be due to higher speed and tighter radius
-The resultant force of the combination of the two force components compared to the edge angle is what determines if the edges hold or not. Ron refers to this as the platform angle.

Now this means that to hold an edge in the steeps you either have to increase the edge angle OR increase the second force component (off course the best is to do both).
Up to moderate speeds and steeps and on grippy surfaces it works pretty good to just increase the edge angles, but pretty soon you will reach a limit, for example:
-in soft snow the resultant force is too much along the snow surface and the ski will break loose because of "shaving"
-On ice the ski can very easily break out and skid.
-If you are going very fast the edge angle is larger than what you can handle (read hip to the snow angles)

Now if it easy to realize that if the second force is larger the edge hold will be better. If we take the example above it is like making the force pushing the skis down into the snow three times larger.

So, the core of this is simply that if you want your edges to hold under tricky circumstances you need to have more dynamics in your skiing, i.e. a short but intense edge engagement followed by a longer "float" with very little pressure. One way of viewing this is that if you have this force component significant when the edges are not engaged you are wasting it.

How you get the dynamics is a whole new subject, but some examples are:
-Old school push edge set where you push down on you edges short and abruptly with muscular effort to get a float into the next turn.
-Modern SL turns where you float through transition, delay the edge set by angulation instead of pushing, set the edges by "landing" with already extended leg. Still above the fall line. Continue increased edge angles and counter until the vaulting effect (Or toppling as it is called in this thread) starts to throw you upwards and into the next turn. Retract at exactly the right moment to get a new float into the next turn.
-A longer GS turn where the float is longer so that the body is almost upright in the middle of the transition, but there is still a float similarly to the SL turn.

The tell tale sign that this is going on in a montage is that the CoM is going up and down. You can see this in most WC footage.

In the context of this thread you can view this kind of float as a kind of falling from one turn to the other, where the state of the fall is given by linear and angular momentums as well as the external forces (gravity and friction) as JASP explained. As said, "semantics".

Oisin, the problem with an early forceful extension is that you disrupt how the second force component is distributed throughout the turn. This means you are compromising both higher edge angles and edge grip later in the turn.
FoM, same goes for having too much snow contact in transition, it will make high level dynamic skiing impossible.
Quote:
Originally Posted by Jamt
................Oisin you seem to imply that a forceful extension early in the turn is the go to move for racers..........

......
Oisin, the problem with an early forceful extension is that you disrupt how the second force component is distributed throughout the turn. This means you are compromising both higher edge angles and edge grip later in the turn.
FoM, same goes for having too much snow contact in transition, it will make high level dynamic skiing impossible.

Jamt

I said I was done talking but, oh well........... I'm not sure what the "go to move" means but I've become a little tired of responding to things I've allegedly said that seem to have been uttered by some imaginary straw man whom I've never met. I'm not entirely certain why racers use this move although I see them do it. Someone suggested that these racers are indeed falling and I've suggested they may not be. I do think  it's preferable to falling though I suppose if you want to argue such semantics skiing itself could conceivably be described as falling. This is just a move I've noticed in racing that I've experienced at times in my own skiing. I find it fun to play with, as I've said, and it does have its uses. For some reason JASP seems to think I said this the only tactic to employ all the time or something to that effect. It certainly wasn't my intention to say that and I don't think I did. (re-read my posts if you like)  I think you are probably correct about it compromising higher edge angles and grip later in the turn. It does prepare you for a very early edge release at the end of the turn though and in that situation you may not want high edge angle or strong edge grip at that point.  That was the point I was making when I described my own experience on very hard snow/ice i.e. it prepares you for a very "light" turn completion where edge grip might be problematic or perhaps where you might want  to have a shorter line.  Anyway once a skier has this in his toolkit he can explore situations in which it may be useful. As I said it beats falling although falling is probably worth exploring as well, if you can avoid being injured.

I really think skiing for me is about exploring (and sharing) all facets of movement and not about being top dog or the consummate expert and I suppose this can be misunderstood.

I don't particularly like the term falling, because it implies loss of control, and that is far from what is going on. During the float phase you have very little contact with the snow so in this sense you are not in balance, but you will be once the edges engage again. What about a free-skier doing a big-jump? Is he out of balance in the air and then recover in the landing? IMO no, he is in control, he is not falling through the air. He might fall when he lands but that's something else.

Oisin, here are some quotes from you that led me to what I said about your implications:

Quote:
Originally Posted by oisin

So, you might well ask, what is happening here that allows them to be inclined down the hill and strongly engaging their edges without falling over? Are they really falling down the hill? The answer is that they are balancing against forces much the same way that we always balance while skiing. In this case it is the force created by a forceful extension just as the skis roll onto their new edges that produce the force required to balance against during that very brief moment they are inclined down the hill.

I very much doubt that any top racer uses a forceful extension just as the skis roll on to their new edges. That would pretty much destroy the rest of the turn

Quote:
Originally Posted by oisin

the turn is initiated there is often a phase in which the skier appears to be inclined down the hill, usually accompanied by extension. I don't disagree that you could fall down the hill at this point and play catch-up either. I'm just saying that is not usually what you are seeing.

How would a forceful extension help balance if you are inclined. The force vector would pass close to the CoM and do very little for balance.

Quote:
Originally Posted by oisin

The effect of a forceful extension to achieve crossover is to release the edges simultaneous with the movement of the body across the skis. That's a pretty nitty point I must admit but consistent with good mechanics of skiing.

Forceful extension to release. It was a long time since I saw that in racing.

Quote:
Originally Posted by oisin

Answer: "strong edge and pressure moves". which are exerted, not down the hill per se , but diagonally into the ground.

Hmm

Quote:
Originally Posted by oisin

The force that tends to pull us to the outside of a turn is angular momentum. Anytime a moving body changes direction momentum tends to want to keep us moving in the direction we were formerly moving. In a turn this means that force is is toward the outside of the turn (did I say that already?) Ok, so at any given moment a component of this force resolves itself to varying degree into the feeling we are being pulled to the outside. We resist this force with edging and our legs, by pushing against the grip we've created on the snow. We balance against this normally with an inclined stance.

Angular momentum is not a force. I guess what you are trying to state is Newtons first law of motion "

 Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it.

For the record Oisin...post 37 is where you entered this discussion, here is the entire post...

Originally Posted by oisin

I try to avoid falling while skiing.

I suppose it is partly a matter of what level skiing you aspire to. Falling implies a loss of control to me but I'll leave it up to you folks. If you want falling to be what you do while skiing well then so be it. If you aspire to something better then look at really high end skiing and I mean racers at the World Cup level you will see very early crossover and edge engagement. There are technical reasons for doing this that I won't go into now but if you examine the sequential photographs that Ron LeMaster publishes you can clearly see that they usually have crossed over their skis and are inclined down the hill way before the fall line. Usually the movement to achieve this has begun just after passing the gate. So, you might well ask, what is happening here that allows them to be inclined down the hill and strongly engaging their edges without falling over? Are they really falling down the hill? The answer is that they are balancing against forces much the same way that we always balance while skiing. In this case it is the force created by a forceful extension just as the skis roll onto their new edges that produce the force required to balance against during that very brief moment they are inclined down the hill. This is high energy, fast skiing. Try this while skiing slowly and you really will fall down the hill but try it at moderately fast speeds in the context of athletic skiing and you will find that you will be able to carve and even shape the turn somewhat before you even reach the fall line so that the rest of the turn is just completing the arc and preparing to move into the next turn.

The smugness of the opening sentence aside, you go on to suggest something "better" and offer insight into what WC level skiers do and suggest pictures from Ron's website are proof of that opinion. You continue and use the word usually several times to suggest that strong extension move and strong edge engagement are more common than they are at that level. Sorry if questioning that idea ruffles your feathers but I do question your understanding of WC level skiing and of the montages Ron posts on his website. I'm not saying that to be mean, or to prove anything beyond pointing out the holes in your theory. I even posted a wiki definition because you seemed to be so mixed up about linear and angular momentum. I rarely do that because a definitions debate is usually unproductive. I like the idea that you stick to your guns but in this thread I must say you seem to be way off base. Extension to maintain contact through the float phase cannot be mistaken for early and strong edge engagement. Two different moves with two entirely different outcomes.

Quote:
Originally Posted by justanotherskipro

For the record Oisin...post 37 is where you entered this discussion, here is the entire post...

........ You continue and use the word usually several times to suggest that strong extension move and strong edge engagement are more common than they are at that level. ........

And then I respond by clarifying what instances I am referring to:
Quote:
Originally Posted by oisin

Agreed, I believe I was thinking only of that technique which, visually at least, appears to be most like falling. Obviously there are a variety of techniques employed for various reasons.

and again:

Quote:

Originally Posted by oisin

Jamt

This is just a move I've noticed in racing that I've experienced at times in my own skiing. I find it fun to play with, as I've said, and it does have its uses. For some reason JASP seems to think I said this the only tactic to employ all the time or something to that effect. It certainly wasn't my intention to say that and I don't think I did.

and again

Quote:
Originally Posted by oisin

Re the early shaping of the turn:

There may be a variety of reasons why a racer might choose to do this.

and again

Quote:
Originally Posted by oisin

Just Another:

I certainly accept that racers benefit from having a variety of turn types, strategies and tactics. just as our students can.  I was only trying to explain one type of turn in which it would appear  that the racer is falling down the hill.

Sorry if these are out of sequence. I certainly am technically challenged when it comes to using the multi-quote tool.

I don't mind having my responses questioned, I invite that. I would,however, appreciate it more if you bothered to read them.

I own up to the smugness, if that's what it was.

I don't think I am confused about the distinction between linear and angular momentum although it has been a long time since I studied statics and mechanics and I admit to not being on top of the terminology.

I think you continue to miss the point. Early forceful extension can be a means of repositioning the float phase, as you call it to the latter part of the turn . Extension can provide a brief force which allows for early and strong edge engagement.  I know this from my own skiing because, as I explained, I used it to actually bend the ski, prior to the fall line. I would say that any force applied to an edged ski capable of bending it is a strong edging force.  I'm sorry if you continue to think of this as a proposed exclusive and all purpose tactic. It was offered, in the context of a thread on falling  an explanation for what occasionally looks to be a falling move. . Obviously, I should think, it does not appear in all racing turns nor was it ever meant to be a description of all racing turns.

Perhaps we should keep that in mind and get back to the topic.

Yes I guess I continue to miss the point. Do you have a montage or video to identify the move you are talking about?

Here are two videos that both demonstrate excellent controlled float without falling. The first is a recreational skier and the second one is the WC overall champ.

Notice in the first clip that he uses extension in some turns, but they are quite different.

Quote:
Originally Posted by Jamt

I don't particularly like the term falling, because it implies loss of control, and that is far from what is going on.

Here I think you must be paraphrasing what I said myself, so I should be flattered.

During the float phase you have very little contact with the snow so in this sense you are not in balance,

But the point is that you can have more contact with the snow during  the early pase, if you choose to.

but you will be once the edges engage again. What about a free-skier doing a big-jump? Is he out of balance in the air and then recover in the landing? IMO no, he is in control, he is not falling through the air.

Really, it sure looks like falling to me.! Seriously I am being facetious here, of course he is falling through the air.

He might fall when he lands but that's something else.

Oisin, here are some quotes from you that led me to what I said about your implications:

I very much doubt that any top racer uses a forceful extension just as the skis roll on to their new edges.

That would pretty much destroy the rest of the turn

Perhaps but that is what I see happening in some racing turns.

How would a forceful extension help balance if you are inclined. The force vector would pass close to the CoM and do very little for balance.

Yes but it is a vector, as such it has a vertical component.

Forceful extension to release. It was a long time since I saw that in racing.

Look again.

Hmm

Angular momentum is not a force. I guess what you are trying to state is Newtons first law of motion "

Angular momentum, momentum, is a result of force and velocity. The rate of change of that or its resultant is experienced as a force (F=MA) so there is unquestionably a force component. Sorry if my terminology is flawed. Angular momentum or momenta are what result in the centrifugal force you mentioned in one of your posts. I believe you indicated it was what kept the racer from falling or something to that effect in one of your posts. You introduced that term in the discussion. (Sorry I think it was JASP who did that)

Edited by oisin - 6/1/12 at 7:58am

Oisin, I wonder if you read my post 83 and understood why extension in the wrong place compromises the turn? Sure you may have to extend at inappropriate places because of a previous mistake, but it  is just that, a mistake. An sure a racer may choose to extend in transition if he wants to. I for one teach my racers not to do that, and that has worked pretty well. I think you are mixing up passive extension that racers do in GS turn and forceful extension. If you can show video or montage of the opposite that would be great because then I would definitely have to learn something new.

If you bounce the CoM up and down 0.3 meters with equal acceleration up and down it will take you 0,7 seconds to go from one low position to another. Incidentally this is about the same time it takes to do an SL turn at race speeds. What happens with this time if you forcefully extend on edge change? My guess is you will blow right out of the course.

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