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# Reconciling Foot Squirt™ with Foragonal movements - Page 2

Quote:
Originally Posted by epic

I skied with an Eastern examiner today who asked me what I am "working on" these days. I explained and showed "foot squirt" in my short turns. I was told that I need to be pressing into my boot tongues at the top of the turn. This person will be scoring me at Dev Team tryouts! Aaaaarggghhh, so frustrating! I will be making the best turns I can when I go. This makes my turns better for better or worse.

the thing is at this point in time, you need to explain what is happening to them and ask them why their way is better. "just because it is" is simply not a good enough answer.  Constant forward pressure is simply very good skiing learning to use the whole ski is something for the truly great.  I have seen your turns the edge angles you are getting in the fall line on a brushed short turn are crazy high and in perfect balance.

Also we need to make it so we can start beating them at their own game which has always been my goals was to change the PSIA from the top. The close mindness of the organization needs to go.

The velocity of the feet in the downhill direction (velocity is a vector as you know) is indeed lower than that of the CM in the same direction at this instant. The absolute speed of the feet across the snow is higher than that of the CM. In fact, in Barnes' animation the speed of the feet and the speed of the CM are each constant, feet always having a higher speed than the CM. What changes continually is the component of speed of each that is directed downhill - i.e., the downhill velocity vector of each.

Quote:
Originally Posted by justanotherskipro

If turning across the hill slows us down, and the feet are turning further across the hill than the body, the feet naturally would slow down more than the body.

Actually if you understood the concept better you would know that the animation shows constant speed because it cannot show the variable speed. So don't be tricked into forgeting the basic physics of a ski turn and taking the animation too literally. The skis accelerate turning into the fall line and they slow down as they turn across the hill. So a more in depth and accurate description of the tactic needs to be developed. Are we minimizing the feet slowing down by not introducing delay moves? Yup. Is the body getting ahead (relative to the bottom of the hill) due in small part to the feet slowing down as they turn across the slope? Yup. Does that mean the wider arc of the skis doesn't contribute to the body's ability to meet the feet at the control phase? Nope. The dual paths theory includes all of this and so much more. Bob might need to chime in here as well but  I just hate to see comments like the feet travel at a constant speed get traction when it's totally false. That just leads to confusion when someone actually feels the feet accelerating during these turns.

Well somewhere in these animations we'd be able to get a lot of answers.  It you read the paper associated with the newscientist report on Matthew Brodie's work you get an idea of the complexity of actually capturing the skier's movements.

How it works:

Video from newscientistvideo

Multiple viewpoints of skier:

Well those last three posts really clear things up, but I guess we'll never really know until they get the Large Hadron Collider up to full speed.

Quote:
Originally Posted by epic

Well those last three posts really clear things up, but I guess we'll never really know until they get the Large Hadron Collider up to full speed.

Any day now, any day.  Once it's up to speed, then it's up to the theoreticians:

Think speed,

CP

Edited by CharlieP - 1/7/11 at 5:17am
Quote:
Originally Posted by justanotherskipro

Actually if you understood the concept better you would know that the animation shows constant speed because it cannot show the variable speed. So don't be tricked into forgeting the basic physics of a ski turn and taking the animation too literally. The skis accelerate turning into the fall line and they slow down as they turn across the hill. So a more in depth and accurate description of the tactic needs to be developed. Are we minimizing the feet slowing down by not introducing delay moves? Yup. Is the body getting ahead (relative to the bottom of the hill) due in small part to the feet slowing down as they turn across the slope? Yup. Does that mean the wider arc of the skis doesn't contribute to the body's ability to meet the feet at the control phase? Nope. The dual paths theory includes all of this and so much more. Bob might need to chime in here as well but  I just hate to see comments like the feet travel at a constant speed get traction when it's totally false. That just leads to confusion when someone actually feels the feet accelerating during these turns.

Thank you for the lesson then. As Churchill said: "Personally I'm always ready to learn, although I do not always like being taught." Do you ever experience a similar sentiment? Banter aside, Barnes' animation is indeed intended to convey a concept, to capture the essence of something. It does this admirably in an idealized form, which is why I referred to it. In real life, of course, skis slow down and speed up for many reasons - that fact doesn't invalidate the principle. Happy "foot-squirting" to all!

Quote:
In real life, of course, skis slow down and speed up for many reasons - that fact doesn't invalidate the principle.

Well said, HDN. Thank you! In most of these animations, I try to strip them down to the bare essential principles involved, and eliminate anything that would be a situational characteristic of a particular turn. Thank you for seeing that!

Best regards,
Bob
Quote:
Originally Posted by epic

Well those last three posts really clear things up, but I guess we'll never really know until they get the Large Hadron Collider up to full speed.

I know, right? all that technology and we don't get much from it. One hopes the phd has a little more. Reading the way the skier was wired up, it's questionable how accurate it is. It relies a lot on gps it seems, but you'd really have to review it carefully. Still, an impressive attempt anyway.

CharlieP, the blackboard photo is awesome. Are you supposed to use binoculars as a student?

This is what probably lies in behind Bob's garage walls, filled with ski turn diagrams.

Jan 7, 2011

Hi Tog:

The second picture I presented (one with the blackboard) is named "This is why I gave up on Physics".  I use to major in physics (up to an MS) and that photo expresses my sentiment to a T.  I knew that sharing a room with you for a few nights would advance my skiing even if it were through osmosis.  So since 2009, I've been waiting for the "quantum leap" in my skiing.  However, I didn't realize that I needed a trigger to get it started.  You said in another thread that  "(skiing) it's like swinging, one smooth movement" was the trigger.  If you read what I posted in Rick's thread on Where's Waldo, I said that I tend to "cut off the top of the 'C' in my turns and being too impatient, rushing into the fall line".  Well today, I thought about "being like swinging, one smooth movement".  I think that I've corrected cutting the top of the 'C'.  Thanks, roomie.

Think snow,

CP

Quote:
Originally Posted by Tog

Quote:
Originally Posted by epic

Well those last three posts really clear things up, but I guess we'll never really know until they get the Large Hadron Collider up to full speed.

I know, right? all that technology and we don't get much from it. One hopes the phd has a little more. Reading the way the skier was wired up, it's questionable how accurate it is. It relies a lot on gps it seems, but you'd really have to review it carefully. Still, an impressive attempt anyway.

CharlieP, the blackboard photo is awesome. Are you supposed to use binoculars as a student?

This is what probably lies in behind Bob's garage walls, filled with ski turn diagrams.

Hey CharlieP -

How in the heck did that short little guy manage to write things that high up on the blackboard?

.ma
Quote:
Originally Posted by michaelA

Hey CharlieP -

How in the heck did that short little guy manage to write things that high up on the blackboard?

.ma

Up-unweighting.

I'm not sure I share the feeling that a theory not matching reality is a good thing. IMO there is no need to suggest speed is constant to get the point across. The foot speed being higher overall is sufficient to support the idea that in a reaching slalom turn the feet are allowed to freely swoop across the hill while the body's path doesn't include moving as far across the hill. Like I said before a student experiencing that acceleration as they turn into the fall line but erroniously believing the feet and body should be moving at a constant speed, would either think they're doing something wrong, or would question the validity of the idea. So why even go there, it adds nothing substantive to the idea.

Quote:
Originally Posted by justanotherskipro

I'm not sure I share the feeling that a theory not matching reality is a good thing. IMO there is no need to suggest speed is constant to get the point across. The foot speed being higher overall is sufficient to support the idea that in a reaching slalom turn the feet are allowed to freely swoop across the hill while the body's path doesn't include moving as far across the hill. Like I said before a student experiencing that acceleration as they turn into the fall line but erroniously believing the feet and body should be moving at a constant speed, would either think they're doing something wrong, or would question the validity of the idea. So why even go there, it adds nothing substantive to the idea.

I'd like to respectfully suggest that the "theory" does in fact match reality - at least in this idealized "perfect" sequence. You are quite right that the skis accelerate in the fall line - in fact the skis are accelerating all the time, at every instant, throughout the entire turn, as is the CM, and yet their speeds may each remain constant - how can that possibly be so? The clue lies in the statement I made earlier that velocity is a vector - i.e., it has both magnitude and direction. Speed, on the other hand, is scalar. The final item is the equation a=dV/dT with an understanding that gravity is an acceleration, not a force. In the spirit of self-guided discovery, I'll leave it at that and ask you to think about it again.

Edited by HardDaysNight - 1/9/11 at 8:32am
While it is certainly true that the feet may speed up or slow down at any point in a turn, through intentional movements of the skier, and it is certainly possible (perhaps even likely) that the feet gain speed as they turn down the fall line and then lose it again as they reach the completion of the turn--it is not necessary that this happens. Indeed, with the sophisticated fore-aft movements that we've been discussing, it is very possible that the feet do not accelerate (gain speed, that is) down the fall line, as they are being actively pulled back beneath the skier's center of mass. Likewise, the feet may not slow down through the completion phase, even as the skier's body does, due to the edge release and release of effort that allows them to (feel like they) "squirt" forward ahead of the body in the transition.

Remember that it takes external force to cause acceleration (which means any change of motion including increasing or decreasing speed or changing direction, as HardDaysNight has explained). For the feet to slow down, therefore, some external force must act on them. But as we release the edge(s) and let the feet go in a turn completion, we release virtually all of the external forces acting on the feet and skis--which means that they will not, in fact, slow down. Conversely, it is the deliberate "foragonal motion" of driving the hips forward and diagonally downhill relative to the feet that forces the feet to slow down at the end of the turn. And that is the problem with "foragonal," at least as it is typically misunderstood and misapplied.

More later--gotta go make some turns.

Best regards,
Bob
Quote:
Originally Posted by epic

I skied with an Eastern examiner today who asked me what I am "working on" these days. I explained and showed "foot squirt" in my short turns. I was told that I need to be pressing into my boot tongues at the top of the turn. This person will be scoring me at Dev Team tryouts! Aaaaarggghhh, so frustrating! I will be making the best turns I can when I go. This makes my turns better for better or worse.

You know epic, if you can explain yourself as well as the concept has been explained here you should impress rather than detract from your scores at your try outs!  Challenge your selector to make dynamic round across the fall line short turns and demonstrate what he is advocating.  He should notice that he is probably not doing what he professes to do?  If he is, he is getting jammed up and making crappy turns.  If you truly understand the concept and your examiner/selector is professional enough to listen and understand your thoughts, it should become apparent to him the merits of what you describe.  Of course, you could always print out this thread and just hand it to him and ask him to read and consider it!

Hey Bob,

I asked Lemaster and his opinion was,  "In a pure* carve that constant speed could occur. Maybe, but probably not since a pure* carve rarely occurs out on the hill". That's another can of worms that I'm not trying to open, all I'm saying is the term constant can lead to confusion among students. Constant speed, or variable speed, really doesn't change the finish of a "swoopy" reaching slalom turn. Conserving momentum (both angular and linear) through the transition is the key here regardless of how close we get to actually acheiving constant speed.

As far as acceleration being a function of external motive forces only, well thrusting the feet forward with muscle power would certainly be an exception to that rule now wouldn't it.

BTW, We watched a Joulbert presentation last night and saw several examples of jet turns (not the commonly misunderstood variety though) and avelmont, replemont (spell?), S turns, serpent move, etc...

It struck me that forty years ago the foot squirt, Foragonal, and even the stivot were all being done They just were called other names. We watched videos of current stars and Killy's contemporaries doing the same moves. So while things change over time, it's remarkable how little new there really is when it comes to movements. It was also interesting to find out exactly what a jet turn really is, what avelmont and replemont are, and how this thread is all about these very same movements and maneuvers.

To return to what I said three times now, constant speed isn't a necessity and IMO not all that important when it comes to conserving momentum and as much foot speed as we can through these turns. Especially when our students more than likely cannot execute a pure* carve with that theoretical "constant foot speed". Would that variable foot speed confuse them if we prescribe it to be a constant? I say yes. So why not leave it at "conserving as much speed and momentum as possible" and leave yourself a little wiggle room?

Respectfully,

JASP

jasp, I don't get the problem really.

As far as students go I don't see describing "constant foot speed" at all nor mentioning "conservation of momentum". Such topics would certainly confuse almost anyone unless they're really keyed in to these discussions and also, would add little to making a difference in how they turn. Maybe it's because I don't understand what you're getting at though.

Quote:
Originally Posted by Bob Barnes
...
Remember that it takes external force to cause acceleration (which means any change of motion including increasing or decreasing speed or changing direction, as HardDaysNight has explained). For the feet to slow down, therefore, some external force must act on them. But as we release the edge(s) and let the feet go in a turn completion, we release virtually all of the external forces acting on the feet and skis--which means that they will not, in fact, slow down. Conversely, it is the deliberate "foragonal motion" of driving the hips forward and diagonally downhill relative to the feet that forces the feet to slow down at the end of the turn. And that is the problem with "foragonal," at least as it is typically misunderstood and misapplied.

Note: The foragonal concept was also discussed last season in this thread started by vailsnopro:

First off Bob,, I need to express my concern over the number of times you have used the word "foragonal". Perhaps it's just an indication of the epidemic use of this word, but since Finndog brought it up in Snowmass I realize it's caused no end of distress to you.  It is gratifying that you are using the apparently eastern spelling, constructed by someone out here who at one time read "How to Construct a Word",  instead of "forwagonal" that is used in the west. Perhaps it's because you're from Maine?

We'll know it's a true epidemic when a Canadian version of the word comes out where they've managed to replace at least one of the 'a''s with an 'o'.

By "deliberate" motion don't you really mean "sudden" or discontinuous? If one is letting them selves "go down the hill" or continually moving the body in that direction then it's happening anyway, not just suddenly, no? From what you're saying I get that it's the sudden movement "foragonally" that stops the feet and makes the turn not smooth.

Alright CharlieP!

Glad it made a difference. I stole that swingset analogy from someone anyway, just can't remember who. It will also prevent the sudden foragonal movement that the forwagoneers misapply also.

Quote:
Originally Posted by justanotherskipro

Is the spinning ice skater a closer model? The longer their arms are extended the slower they spin but do the hands actually travel faster when extended? It seems likely. Although I'm sure one of our bears with a doctorate in physics could answer that question better than I can. Anyone seen or heard from Physicsman lately?

I'm no Physicsman, but from a physics points of view, I think you're right.

The question is, does the increase in hand speed caused by the increase in radius outweigh the decrease in rotation speed. The decrease in rotational speed is caused by conservation of angular momentum, which is defined as moment of inertia x angular velocity.

The decrease in rotations per minute would depend on the mass that you are extending out (IE the arms). In physics we can represent this as mass at a point - think of it as the centre of mass of the arms. The decrease in roational speed would depend on how large the mass is and how far from the centre it has moved.

The hands are always further out than this theoretical centre of mass. So the increased radius for the hands should have more effect than the reduction in rotations/minute.

(PS I am a "lapsed Physicist" so please excuse any lack of precision.)

(PPS I should have mentioned that both moment of inertia and hand speed vary as radius squared)

A serpent striking is how the foragonal move was described in the late sixties / early seventies. For that to happen the upper body is thrust into the new direction (middle of the next turn) as the feet turn across the hill and slow down. Others have described it as the feet stalling out and the body continuing to move into the new turn. Even others described it as leap frogging, catch and release, or even gorilla turns. Regardless of what you choose to call this move it involves the feet slowing down, or at the very least the body and feet moving at the same speed across the hill and the body being thrust into the new turn.

Contrast that with the idea of a transition where the feet are passing under the body without any stalling out / slowing down. The body taking a more direct path to the middle of the next turn is the only way to remain standing. A stivot subsequent to the feet speeding through the transition is certainly one way to scrub off some foot speed and mitigate any acceleration as the skis turn into the fall line. If a pure carve is occurring, then the skis would need to take an even longer path to stay relative enough to the speed of the body for us to remain standing. We can certainly discuss and include the idea of the float phase where our stance is less relevent but even then we need all the parts to move into proper alignment before we engaged the new edges and balance on the newly engaged skis. If we don't acheive that alignment, then we fall, period. Bode's blowing up in a race is a perfect example of this IMO. What's most important here is the middle and last part of the turn where the skis are more likely to be carving. Scrubbing speed here upsets the timing of the "squirt like" cross over and makes the serpent move more necessary.

Additionally, TOG when you are introducing this maneuver it is very important to articulate the need to maintain as much foot speed as possible through the transition, or said another way, we strive to mitigate the natural tendency of the feet to slow down as they turn across the hill. Is it possible that this is perceived as constant foot speed throughout the entire turn? Perhaps, but IMHO to prescribe it as a "necessary" component of the maneuver overstates the importance of "constant" foot speed and is a distraction to the basic idea of conserving as much foot speed and momentum in the last third of the current turn and the first third of the upcoming turn.

Can we reconcile the two ideas, Yup. Watch Bode, Ligety and just about any world cup racer nowdays and you will see the reaching turn with the feet moving forward and the serpent striking forward move being used. They are valid but contrasting tactical options and a polarity exist between them. (See Weems' book for more details on the idea of polarity I'm using here.) For Epic, who is trying out for a position on the D team, the maneuvers involved in that try out are already established and they don't include the "foot squirt" at this time. Or maybe it is in the mogul skiing activities where the feet slide forward as we absorb. I'm sure Bob can speak to that idea better than me. In any case, it's not implied that the foot squirt is somehow superior, or inferior to the serpent striking move. Perhaps like the retraction turn it may occur in a test activity but the judging criteria and a consensus opinion about a drill that would demonstrate an isolated version of that movement has yet to be developed for that test.

Ski well my Friends,

JASP

Quote:
It is gratifying that you are using the apparently eastern spelling, constructed by someone out here who at one time read "How to Construct a Word", instead of "forwagonal" that is used in the west. Perhaps it's because you're from Maine?
One less keystroke.

Best regards,
Bob
Quote:
Originally Posted by justanotherskipro

A serpent striking is how the foragonal move was described in the late sixties / early seventies. For that to happen the upper body is thrust into the new direction (middle of the next turn) as the feet turn across the hill and slow down. Others have described it as the feet stalling out and the body continuing to move into the new turn. Even others described it as leap frogging, catch and release, or even gorilla turns. Regardless of what you choose to call this move it involves the feet slowing down, or at the very least the body and feet moving at the same speed across the hill and the body being thrust into the new turn.

Contrast that with the idea of a transition where the feet are passing under the body without any stalling out / slowing down. The body taking a more direct path to the middle of the next turn is the only way to remain standing. A stivot subsequent to the feet speeding through the transition is certainly one way to scrub off some foot speed and mitigate any acceleration as the skis turn into the fall line. If a pure carve is occurring, then the skis would need to take an even longer path to stay relative enough to the speed of the body for us to remain standing. We can certainly discuss and include the idea of the float phase where our stance is less relevent but even then we need all the parts to move into proper alignment before we engaged the new edges and balance on the newly engaged skis. If we don't acheive that alignment, then we fall, period. Bode's blowing up in a race is a perfect example of this IMO. What's most important here is the middle and last part of the turn where the skis are more likely to be carving. Scrubbing speed here upsets the timing of the "squirt like" cross over and makes the serpent move more necessary.

Additionally, TOG when you are introducing this maneuver it is very important to articulate the need to maintain as much foot speed as possible through the transition, or said another way, we strive to mitigate the natural tendency of the feet to slow down as they turn across the hill. Is it possible that this is perceived as constant foot speed throughout the entire turn? Perhaps, but IMHO to prescribe it as a "necessary" component of the maneuver overstates the importance of "constant" foot speed and is a distraction to the basic idea of conserving as much foot speed and momentum in the last third of the current turn and the first third of the upcoming turn.

Can we reconcile the two ideas, Yup. Watch Bode, Ligety and just about any world cup racer nowdays and you will see the reaching turn with the feet moving forward and the serpent striking forward move being used. They are valid but contrasting tactical options and a polarity exist between them. (See Weems' book for more details on the idea of polarity I'm using here.) For Epic, who is trying out for a position on the D team, the maneuvers involved in that try out are already established and they don't include the "foot squirt" at this time. Or maybe it is in the mogul skiing activities where the feet slide forward as we absorb. I'm sure Bob can speak to that idea better than me. In any case, it's not implied that the foot squirt is somehow superior, or inferior to the serpent striking move. Perhaps like the retraction turn it may occur in a test activity but the judging criteria and a consensus opinion about a drill that would demonstrate an isolated version of that movement has yet to be developed for that test.

Ski well my Friends,

JASP

Ok, I get what you're refering to now. That whole serpentine/foragonal history is new to me.

I must say that when the foragonal move is talked about I don't hear it as a sudden move, but it is a move so I guess it always is interpreted as starting from the transition and being more like you talk about with the "Serpent Striking".   I guess a common interpretation is as Bob talks about - a sudden, deliberate move. Thus, at the transition, I'd have to suddenly hurl myself "foragonally" down the hill, which would slow the feet. Rinse, then repeat.

I'd prefer to just describe it as letting the feet go, instead of talking about foot speed, momentum etc.

Would one be able to execute the let the feet go,  and have the body meet up with these skis and boots? I doubt it, but I never skied those things.

Here's a photo of the Serpentine turn:

From:  "Ailing From Avalement", by Stu Campbell

Skiing Heritage Journal, Sept 2002,  pg24 ; Link: SHJ Sept 2002

There's also this discussion of Serpentine Turn and Cross Under:

Today we speak a lot about the core moving into the new turn and releasing the torso towards the apex of the next turn. If you look closer at the third photo in the Joubert montage, I think the edge change has not happened yet. Even though the head and shoulders are already downhill of the feet. Contrast that photo with this one and you can see the similarities and the differences.

Photos three, four, and five show angulation and a countered stance being maintained (anticipation?) even though the edge angle is being reduced. The net effect is seen in photo five where the head and shoulders are already inside the new turn. Is it as severe and sudden as the Joubert example that seems to happen quickly near the edge change? Nope,but the net effect is the same, the head and shoulders preceding the rest of the body into the next turn. When the pelvis joins the upper body inside the turn (photo six) Ted is aligned very well and ready to work the newly engaged skis. I'm sure others will argue that there are differences I haven't covered but I actually hope they do that so we can all get a more complete understanding of all of this.

Edited by justanotherskipro - 1/10/11 at 9:41pm

These short radius turns show the "squirt" and the different paths of the skis vs. the COM.

Quote:
Originally Posted by bbinder

"Foot Squirt"(tm):  What a term -- describes exactly the feeling to describe this move -- I love it!!!

Wow, just found this thread.  I've been doing these turns and calling them "scoop turns, since the skis "scoop" forward at the end of the turn.  But "foot squirt" sounds more fun.

I get fussed at big-time any time I do these in front of my mountain's trainers, so it's nice to see them celebrated here.  I get such a rush of control from driving the skis this way.

Great thread.  Was playing with this this morning and found it really effective, particularly on short turns.  On steep sections it gave this freeing feeling and yet still a feeling of control.

Talked to an old timer at the mountain about it and he said they used to call this "slicing" or a "slice turn."

Another day of playing with this.  It has changed my skiing for the better, a pretty decent amount.

Comment I got from a Level III with good eyes is that I was exhibiting much more leg flexion and extension.

I was skiing top to bottom steep trails and flying with a feel of great confidence and stability.  I attribute a lot of that to this movement of letting my ankles open and allowing myself to feel the backs of my boots - briefly.

Every race coach I spoke to said, "of course."  Every PSIA type said "hmm, interesting."  All admitted on self-evaluation that "yeah I guess I do feel the backs of my boots a bit."