 Poster: A snowHead
|
GrahamN, but your carpet example is static just like the maths models and i dont think is relevent.
think instead about skiing slow carves one footed on grippy snow. When i do this and get pressure on the shovel I can change the radius of the turn quite easily by bending the ski as it bites into the surface. ie that slight pressure on the shovel whether through rotary torque, forward weight into the boot, deeper edge engagement, femur steering etc. will have a very pronounced effect on turn radius along. I will grant that this comes with some increase in edge angle but do you take my point?
|
|
|
|
|
|
Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
|
| skimottaret wrote: |
| Graham, I havent been following the maths closely so forgive me if i get this wrong... My gut feel initially was that the differences between the models and real life were fairly small and secondary effects are what is keeping the skis parallel when making carved/surved tracks. Your analysis of the model showing a typ rec skier is out by a matter of only degress and inches during a "normal" turn seems to support that. |
But that is completely contradictory to saying you tend toward V8's view. He's been saying all along "no they're parallel, but the angles are the same, and I'm not diverging/converging" - and gone on from that to extrapolate to a completely false mathematical explanation. The fact that the differences may only be a few inches or degrees is not the issue, it's that those differences exist. If you accept that, then you allow for the fact that those differences may have to increase as you get to higher performance levels, to a point where it may be difficult to make them subconsciously, which is precisely what FastMan's quoted post addresses. This is a similar kind of situation to where the approximations inherent in Newton's laws are perfectly adequate to get us to the moon, but we'd need Einstein to get us to the stars.
|
|
|
|
|
|
Well, the person's real but it's just a made up name, see?
Well, the person's real but it's just a made up name, see?
|
GrahamN, Good point, well presented. Clearly a relevant factor, but I think ski flex is still very significant. If the tip bites, even on a rock hard surface, it will still bend the rest of the ski due to the dynamic loading. Same goes for the tail. It's not just a simple static side load like you are applying to the carpet. But your point is valid, soft snow will allow more ski bending for sure.
Yes I did a lot of my skiing on straight skis (Rossi 3G, 4S etc) and I could carve on them, but not as easily or cleanly as modern shaped skis. They did have some sidecut from memory, but very slight compared to today. I was too young to think about it in this kind of way back then, but the carving radius must have been generated almost entirely from the ski bending. How else would it carve an arc? The inside ski was along for the ride in those days too and just got in the way when racing. There was none of the current emphasis on even weight distribution and simply rolling onto the edges. Everything was forced into shape, making progress more tiring. We have it easy now I can assure you 
|
|
|
|
|
|
You need to Login to know who's really who.
You need to Login to know who's really who.
|
| skimottaret wrote: |
| ..think instead about skiing slow carves one footed on grippy snow. When i do this and get pressure on the shovel I can change the radius of the turn quite easily by bending the ski as it bites into the surface. ie that slight pressure on the shovel whether through rotary torque, forward weight into the boot, deeper edge engagement, femur steering etc. will have a very pronounced effect on turn radius along. I will grant that this comes with some increase in edge angle but do you take my point? |
But that's not then a purely carved turn - there is some degree of sideways movement from at least part of the ski, and the track is broadened by some amount - possibly small. A situation I also covered in that post back on page 3. As an example I calculated that the broadening if the ski was turned only by rotation (femur steering, whatever) would be about 2mm. Do it by some kind of pressure effect on a soft snow surface it may be less, but it's still going to broaden the track (and also cause some slow down as the edge motion has some lateral component and associated additional friction). Actually, although you can't see the tracks, this is very obvious on plastic as the ski sounds completely different as soon as you do anything other than a pure carve. Maybe reason number say 1.5 why you should ski on plastic  ?
Last edited by You need to Login to know who's really who. on Thu 17-04-08 14:24; edited 1 time in total
|
|
|
|
|
|
Anyway, snowHeads is much more fun if you do.
Anyway, snowHeads is much more fun if you do.
|
uktrailmonster, so what happened on rock hard pistes - or did they even do the injection type thing back then? (I guess we've lost Martin Bell by now with this anal wrangling - shame). Or was it just pivot and lock, until you got a bit of softness back in the surface?
We do spend a long time in these arguments talking about the perfect carve - as the holy grail  - but we should remember that it's really only a limiting case of a spectrum of different turn combinations. But for the ski to have minimum friction, and so go fastest, the ski has to travel travel purely along the direction of its edge. Next can of worms?
|
|
|
|
|
|
You'll need to Register first of course.
You'll need to Register first of course.
|
GrahamN, I think our posts crossed but to reply to your 13:00..
Yes i know my position is contradictory. Some of v8's assertions about the maths are incorrect, (i dont want to argue for him but my position). i tend towards his view as I think his underlying arguements are sound in that we can demonstrate virtually parallel clean carved turns without diverging. His mistake is fiercely argueing the first order effects of the models are wrong when he should be agreeing with the basic geomtry and physics you guys righly point out. He should instead focus on trying to argue why the models dont stack up with the "real world". The models arent perfect and shouldnt be slavishly followed as he rightly points out.
I would argue that these static models, like most physics models are close but the secondary effects/forces are not taking into account into the actual dynamics of the physical problem. Hence me trying to uncover the mechanism that allows us to do on snow what the models say we cant.
To reply to my one footed example. Sorry but staying less than theoretical i recon I can carve a pretty clean one footed turn on the outside ski without visible skidding in good grippy snow. I also think i can vary the radius of the turn by pressuring the shovel, so body mechanics and force can affect turn radius allowing one to have two "parallel" carved tracks..
Lets not forget that skis dont have consistent stiffness along their length. The tips are quite a bit softer than the middle or tails. and again this secondary issue isnt in the models you argue for.
|
|
|
|
|
|
|
|
|
Makes me think that at the next Snowheads bash there should be a longboard ski day ala TGR. Maybe combine it with the all-in-one day? Everyone on 2m+ sub 70mm tip/tail skis.
|
|
|
|
|
|
|
|
skimottaret, fair dues, and I'm not going into bat on this one, as I agree with you that adjusting the pressure point along the ski can change the turn shape (as I've already said). We may differ over the explanation of how that arises, and whether that's still a carve or not, but the important point is that it does happen.
My only remaining comment on the modelling thing is that models may not be perfect, but neither is human perception, and people (particularly non-scientists) are very good at misinterpreting what models say, and we've had some doosies in this thread. Frequently it's not the model that's saying something is impossible, but someone's misinterpretation of what the model says, or its underlying assumptions, that results in a rejection of its conclusions.
Last edited by After all it is free  on Thu 17-04-08 14:55; edited 1 time in total
|
|
|
|
|
|
You'll get to see more forums and be part of the best ski club on the net.
You'll get to see more forums and be part of the best ski club on the net.
|
| skimottaret wrote: |
| I would argue that these static models, like most physics models are close but the secondary effects/forces are not taking into account into the actual dynamics of the physical problem. Hence me trying to uncover the mechanism that allows us to do on snow what the models say we cant. |
I would put it slightly differently: the mathematical/physical point is that (1) putting down parallel tracks while (2) both skis do the same thing at the same time is theoretically AND practically not possible; the skiing point is about achieving an optimisation whereby the deviation from (1) or (2) or some combination thereof is minimised (such that it would take a quite acute observer to notice).
Last edited by You'll get to see more forums and be part of the best ski club on the net. on Thu 17-04-08 14:48; edited 1 time in total
|
|
|
|
|
|
|
|
| GrahamN wrote: |
uktrailmonster, so what happened on rock hard pistes - or did they even do the injection type thing back then? (I guess we've lost Martin Bell by now with this anal wrangling - shame). Or was it just pivot and lock, until you got a bit of softness back in the surface?
|
injection type thing? Sorry I'm not familiar with that term?
I wasn't good enough to carve cleanly on a rock hard piste. Actually thinking back, the whole concept of clean carving was rarely discussed outside of racing. Short swings were fashionable in the 80s and much talk was about dealing with moguls, not carving clean lines on groomers. Some degree of skidding was inevitable for all but the longest radius turns. There were no internet forums either, so you didn't really debate these things with anyone outside your ski club.
|
|
|
|
|
|
snowHeads are a friendly bunch.
snowHeads are a friendly bunch.
|
|
GrahamN, i think we mostly agree on this stuff. i guess i however take a much less rigorous view to the maths (as i am rubbish at maths and still have a headache from my concussion last week) nothing wrong with arguing for correctness and precision though when incorrect statements are made...
|
|
|
|
|
|
And love to help out and answer questions and of course, read each other's snow reports.
And love to help out and answer questions and of course, read each other's snow reports.
|
|
skimottaret, I hadn't heard about your concussion - hope you're ok. I'm not meaning to start another argument - genuine curiosity - were you wearing a helmet?
|
|
|
|
|
|
|
|
| uktrailmonster wrote: |
| injection type thing? Sorry I'm not familiar with that term? |
Sorry...water injecting race pistes to make them harder.
|
|
|
|
|
|
You know it makes sense.
|
|
laundryman, DOnt worry this thread has more points than a snowflake. yes i was wearing one and very glad i had donned it. still have blurred vision in one eye and am still seeing odd bits of stuff floating around in my eyeball. They thought i had detatched a retina but fortunately that was ruled out in France after seeing an opthmologist a few days after the hit.
|
|
|
|
|
|
Otherwise you'll just go on seeing the one name:
Otherwise you'll just go on seeing the one name:
|
|
skimottaret, hope that clears up soon.
|
|
|
|
|
|
Poster: A snowHead
|
|
|
|
Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
|
My initial focus in the debate has been about debunking the need to scissor/diverge in order to ski RR tracks, and to debunk the tighter inside ski radius.
Is everyone now agreed that the two tracks produced by L & R skis are in fact identical rather than one having a smaller radius than the other? Because if you don't think this is the case, we can't move on.
|
|
|
|
|
|
Well, the person's real but it's just a made up name, see?
Well, the person's real but it's just a made up name, see?
|
| veeeight wrote: |
| Is everyone now agreed that the two tracks produced by L & R skis are in fact identical rather than one having a smaller radius than the other? Because if you don't think this is the case, we can't move on. |
Veeeight, let's just let it rest. I think the consensus is mixed at best for you, and at worst pretty much the opposite. You aren't going to agree with GrahamN, LaundryMan and I no matter what lengths we go to. We'll carry on for days otherwise.
|
|
|
|
|
|
You need to Login to know who's really who.
You need to Login to know who's really who.
|
| veeeight wrote: |
Is everyone now agreed that the two tracks produced by L & R skis are in fact identical rather than one having a smaller radius than the other? Because if you don't think this is the case, we can't move on. |
Not even a wafer thin difference? 
|
|
|
|
|
|
Anyway, snowHeads is much more fun if you do.
Anyway, snowHeads is much more fun if you do.
|
| Quote: |
| invoke some jargon to divert/impress the punters to make you look knowledgeable, particularly if on shaky ground, only this time, as on the force/pressure thing, you've been caught out |
Do you still believe that you can apply "early pressure" ??? 
I thought you had learnt from that last debate that it's all about early edge, then build the pressure in the fall line (which was always my initial assertion) therefore you can't "apply" early pressure - but no, you had to read it differently!!! You took umbrage at my use of the word "resultant" instead of "resulting"
| Quote: |
| So given that veeeight has conceeded that the separation in tracks will often be narrower at transition then apex, he has to conceed also that there is divergence/convergence along the path - it's inherent in their definitions. |
No, because your rigid ideal of maths doesn't allow for the fact that I am doing exactly the same thing on both skis simultaneously, edging them the same amount with no rotary input. Ask any good skier on this forum. Show me any current coach that encourages divergence of skis in a turn at low speeds and low edge angles.
| Quote: |
| On a practical note, you seem very anti-inside ski steering (correct me if I'm wrong). Warren Smith on the other hand spends a fair proportion of his DVDs training us to "power steer" our inside skis. |
I did say earlier that as the speeds go beyond recreational and as the angles get higher, the insider ski is steered to match the outside ski (as the outside ski gets more and more dominant). However at recreational speeds skiing arc to arc turns there is no needs to utilise this. I also believe that this is Fastman's position.
| Quote: |
| and (possibly unwisely) made a comment in passing that veeeight's maths was balls. |
It may be balls, but it did show that the tracks we produce in skiing are not in fact of different radii. But conversely, none of the maths/physics models so far have managed to show what actually happens in reality!
| Quote: |
| The only complication being that the lightly loaded inside ski naturally wants to travel in a wider arc than the heavily loaded outer, therefore requiring a bit of correction from another source i.e steering, forward tip loading or whatever. |
So close to the solution!
Last edited by Anyway, snowHeads is much more fun if you do. on Thu 17-04-08 17:06; edited 2 times in total
|
|
|
|
|
|
You'll need to Register first of course.
You'll need to Register first of course.
|
| uktrailmonster wrote: |
| veeeight wrote: |
Is everyone now agreed that the two tracks produced by L & R skis are in fact identical rather than one having a smaller radius than the other? Because if you don't think this is the case, we can't move on. |
Not even a wafer thin difference? |
Well, OK, allowing for wafers. But certainly not like the maths concentric circles! Else your inner ski would be trying to prescribe a tighter arc than the outside ski!
|
|
|
|
|
|
|
|
| veeeight wrote: |
| Else your inner ski would be trying to prescribe a tighter arc than the outside ski! |
The problem with that being...........?
|
|
|
|
|
|
|
|
| veeeight wrote: |
| It may be balls, but it did show that the tracks we produce in skiing are not in fact of different radii. |
Sorry, I don't agree you have shown this at all. All the diagrams you produced were flawed. Please draw me the diagram of a 180 degree turn. They do that in racing from time to time don't they?
|
|
|
|
|
|
You'll get to see more forums and be part of the best ski club on the net.
You'll get to see more forums and be part of the best ski club on the net.
|
| veeeight wrote: |
| Is everyone now agreed that the two tracks produced by L & R skis are in fact identical rather than one having a smaller radius than the other? Because if you don't think this is the case, we can't move on. |
Not in the slightest, and only someone totally delusional and unable to read English could possibly have come to that conclusion. In none of those diagrams that have been posted are the tracks parallel. As I have said about half a dozen times, remove your requirement that they be parallel and then in certain circumstances (principally that you never turn by more than 90 degress) you may be able to describe identical tracks - but they will not be parallel. It has been proved to you time and time again that this is the case but you continue with your delusion that black is in fact white. The left pair of tracks below shows what happens when the skis ARE doing exactly the same thing simultaneously. To get the tracks on the right you have to start the left ski before the right, and they will then do the same things, but never simultaneously.
And no FastMan does NOT agree with you. Regarding low edge angles,
| FastMan wrote: |
| To carve parallel skis, the inside ski needs to ride a higher edge angle, which means the inside ski needs to be tipped onto a higher edge. |
I don't know how many time I have to reference this before you get it.
As SS Bob says there is clearly no point in any further discussion on the subject while you continue with your delusion.
Bye
Last edited by You'll get to see more forums and be part of the best ski club on the net. on Thu 17-04-08 17:55; edited 1 time in total
|
|
|
|
|
|
|
|
| veeeight wrote: |
| And this could well explain why good skiers, that hold a constant ski width, will often have slightly narrower tracks at the transistion than apex (as both skis have the same radius). |
I think this statement encapsulates your confusion. How can these three clauses be consistent?
(1) "hold a constant ski width"
(2) "slightly narrower tracks at the transistion than apex"
(3) "both skis have the same radius" (I assume you mean tracks here).
The acceptance of (2) is one way of meeting the geometrical/mechanical facts:
| laundryman wrote: |
| (1) putting down parallel tracks while (2) both skis do the same thing at the same time is theoretically AND practically not possible |
In this particular way, (3) may be true on some occasions but (1) is not. Given that it's a direct negation of (2), it's hardly surprising.
|
|
|
|
|
|
snowHeads are a friendly bunch.
snowHeads are a friendly bunch.
|
Not trying to fan the flames. but could someone work out the difference in radius between inner and outer ski when doing a 20 metre radius turn and assuming two different centres of radius for each ski (which i believe to be correct). I think we are talking about next to nothing and that the perception of parallel curves is because the differences are so minute as to be imperceptable in practice.
Tryin to make some peace here I believe that V8 recons the curves can be "identical" in that they can be overlaid (which i think is correct). GrahamN is correctly argueing that they cannot be parallel as well, which i am guessing in practice would entail some tip lead /lag? but with the (im guessing) very small differences does it matter?
Last edited by snowHeads are a friendly bunch. on Thu 17-04-08 18:14; edited 1 time in total
|
|
|
|
|
|
And love to help out and answer questions and of course, read each other's snow reports.
And love to help out and answer questions and of course, read each other's snow reports.
|
|
skimottaret, tiny differences in radius yes, but the divergence/convergence effect is still significant (if the small corrections are not made) due to the relatively large distance travelled. It basically scales up exactly like the small sketches.
|
|
|
|
|
|
|
|
uktrailmonster,
| Quote: |
if the small corrections are not made
|
I am thinking that we can make identical tracks that can be overlaid... i also think being able to do that requires some small correction or the maths dont support it. whether that is bending the ski more, more edge angle , scissoring or something else is small beer in terms of the tracks laid down. Im not too sure that the practical divergence is that large as the ski length doesnt change and as the radius increases so doesnt scale up exactly.
|
|
|
|
|
|
You know it makes sense.
|
skimottaret, good engineers question, cut through all this maths purists crap. If the tracks are parallel, then the centres will be the same - mathematical truth. The radii will be therefore be different by the separation of the skis/tracks (this is about the third time I've said this, but no worries, last one was probably several pages back). The answer to the edge angle difference requires a turn radius/edge angle calculator. I've lost the envelope on which I did this calculation, but it will depend on the sidecut of the skis. Remember that a 20m radius turn cannot be carved with anything tighter than 20m sidecut skis though.
Actually, cobbling something together from PhysicsMan's sheet (and he has loads of caveats about the approximations in this calculation), using a 25m radius ski, and assuming 32cm (12.5 inches approx) between the tracks
a 20.32m radius curve requires a 35.6 degree edge angle, and a 20.00 m radius curve requires a 36.9 degree angle.
Tightening it up a bit more,
a 15.32m radius requires a 52.2 degree angle, and a 15.0 radius requires a 53.1 degree angle.
a 10.33m radius requires a 65.6 degree angle, and a 10.0 radius requires a 66.4 degree angle.
If you want the feet a bit further apart than 32cm, 53cm (nearly 21 inches)
a 20.53m radius requires a 34.8 degree angle
a 15.53m radius requires a 51.6 degree angle
a 10.53m radius requires a 65.1 degree angle
If you want a different sidecut, turn radii will scale with sidecut for the same edge angle.
So typically up to 1-2 degrees different. The angle difference is actually greater at the lower edge angle (as the turn radius is less sensitive to angle the closer you get to the sidecut radius, i.e. the flatter the ski). Once again, I repeat, no-one has said that these differences are large, but they have to be admitted. Allowing for that 1-2 degree difference in edge angle removes all this crap about identical tracks needing to be overlaid, and parallel curves are quite possible. Again, no-one (except V8 ) has argued against this solution.
|
|
|
|
|
|
Otherwise you'll just go on seeing the one name:
Otherwise you'll just go on seeing the one name:
|
| Quote: |
Allowing for that 1-2 degree difference in edge angle removes all this crap about identical tracks needing to be overlaid and parallel curves are quite possible.
|
thanks for doing the sums, most informative and i recon all of us can manipulate the inner ski by 2 degrees so therby sorta making a lot of the arguements moot.... 
|
|
|
|
|
|
Poster: A snowHead
|
Firstly, let me say that this thread has got rather out-of-hand and personal. This should be merely a diverting (diverging?  ) little thought experiment, looking at maths and geometry, and pondering how that might be applied to real-life skiing. This thread should have absolutely nothing to do with who is the better skier, racer, coach or instructor, nor about who can make friends with the most racers and coaches in a bar, nor about who knows more British instructor-trainers with the surname Smith  .
| veeeight wrote: |
| MB, I would dispute that scissoring, convergence, and divergence is intent in modern technique or tactics, if trying to ski arc to arc turns. None of us here coach it, we do everything possible to eliminate it, we avoid patterning it. (and I think you're just jerking my chain here ) |
What do think I am, some kind of dinosaur who goes around telling kids to ski-race like this?:
http://bloggbilder.aftonbladet.se/images/519/img_45851dba61c05.jpg
I am honestly not trying to yank anyone's chain. I merely made the observation that small amounts of scissoring are observable in modern racers (when they are racing unconsciously, and not concentrating on looking pretty for the camera). I then merely hypothesized that this phenomenon MAY have something to do with what PM's mathematical models state: that it is impossible to do pure carved turns with a simultaneous occurrence of these three factors: identical radii, identical edge angles, constant track width.
(Actually, this occasional divergence may just as easily have a bio-mechanical cause - have you ever noticed how your tips point outwards when you're riding the chairlift. Fischer have even incorporated this effect into their ski boots.)
By the way, I looked carefully at the diagram below. I actually measured the track width (sad, I know!) between the upper two lines; you can actually see that it is about 1mm greater at the apex than at the beginning or end. So presumably they must diverge and then converge - although again, I don't claim to be an expert on geometry...
| veeeight wrote: |
 |
|
|
|
|
|
|
Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
|
|
|
|
Well, the person's real but it's just a made up name, see?
Well, the person's real but it's just a made up name, see?
|
veeeight, have you ever carved a 360? I have and I'm crap . . . go do it and then get some string and lay a length in each track them measure them. The tracks may be equidistant from each other but the lengths are different. The outer ski has travelled further and faster than the inner ski. THIS CAN BE MEASURED with a piece of string and the simple will to do it and it's not maths . . . it's just string!
Do you understand why the inner ski has a different angle of attack (see your supplied pictures)? It's because the leading ski is further along its arc and pressuring the shovel (if you're in a good posture).
The reason the inner ski is cranked over more in your pics is because for it to provide an equidistant track with a lighter load to deflect it, it must achieve a tighter radius to stay inside the outer ski track
Your drawings show that you're starting the turn with your outside leg forward of the rear and finishing it with it behind. Try to place this in a real world context . . . go through a complete turn in your mind from inception to finish where do your feet start, end and pass each other in the manoeuvre.
I'm trying not to get riled again but this thread has lived up to and beyond my rant of many pages ago and I withdraw my apology 
|
|
|
|
|
|
You need to Login to know who's really who.
You need to Login to know who's really who.
|
|
|
|
Anyway, snowHeads is much more fun if you do.
Anyway, snowHeads is much more fun if you do.
|
Martin Bell, Although the maths purists are correct wiht the theory I think Graham has shown that with just a couple of degrees of additional edge angle on the inner ski we can create RR turns that everybody can agree on .
As a thought experiment this was somewhat useful. for me the interesting bits come when theory and practice dont agree and we try to figure out why. The idea of shovel bending is still my best candidate for why we can lay down tight carved turns. this along with a bit more edge angulation of the inner leg through femur steering and tip lead gets my vote..
Care to contribute some practicalities on "the how do you fix this problem thread"? http://snowheads.com/ski-forum/viewtopic.php?t=39115
|
|
|
|
|
|
You'll need to Register first of course.
You'll need to Register first of course.
|
What a great thread. Seriously.
Thankfully SkiMott't has started a new one.
I still don't understand how anyone ends up with too much tip lead (and I have carefully considered whether I might, and I don't think I do) not what to do about it if they have. On to the other thread (a particularly nice Aligote in my glass right now thanks... )
|
|
|
|
|
|
|
|
Martin Bell,
Ha ha 1-0.. !!
|
|
|
|
|
|
|
|
| GrahamN wrote: |
But how did skiers carve on straight skis? Was it actually a carve, or a refined form of pressure turn? Any insight uktrailmonster? |
Straight skis were not straight..... just less shapely than todays crop.... A carved turn just had a much larger radius than we see these days
|
|
|
|
|
|
You'll get to see more forums and be part of the best ski club on the net.
You'll get to see more forums and be part of the best ski club on the net.
|
So this is what happened IN REALITY today - try and fit a maths model into this if you're really determined.
3 of us - selected super sharp stiff GS skis (the primary reason being that these skis are ultra ultra difficult to pivot once you tip it onto any sort of edge. Being ultra stiff would also highlight if anything other than a edge locked pencil thin track is produced).
Laid down some tracks. Repeated. Walked up and inspected them.
Observations:
1. No skidding. Ultra thin pencil lines.
2. No inside ski divergence at the start of the turn (can't pivot)
3. Simultaneous edging movements on both skis. Same edge angles at the same time.
4. Was expecting track width to be wider at the apex than at transition (skiers holding a constant stance width) but couldn't measure any perceptible difference. Might be reasonable to expect this to change with even higher performance.
I don't know what else to say. What happens on snow is NOT reflected by any of the maths/physics models being thrown around.
Again, over beer, the discussion was around why the reality of being able to produce clean identical RR tracks, one of the points raised when I mentioned carving a 360, drawing a 180 degree turn, is that, again, in reality, whilst you can carve a 180 degrees, or even 360, the tracks will look nothing like concentric circles drawn on paper - simply because circles have a fixed radius, and in skiing we are constantly changing the radius as the turn progresses.
This is why it is false to try and produce paper tracks of 180 degrees or to try and think of concentric circles of 360 degrees, or to think that two circles of identical radius will converge. It won't and doesn't match reality.
|
|
|
|
|
|
|
|
| veeeight wrote: |
| This is why it is false to try and produce paper tracks of 180 degrees or to try and think of concentric circles of 360 degrees, or to think that two circles of identical radius will converge. It won't and doesn't match reality. |
Err, you're telling me you can't actually draw the tracks you make when you carve a 180? You can't imagine what they'd look like if someone took an aerial photo, then draw this on paper? As I said, I don't give a fig whether they're perfect arcs or circles or have altering radius throughout the turn. Just draw it will you? Otherwise I'll believe you can't draw it (or not without differing radii) and you're wrong.
Somewhere when you're carving those lines you will have one ski starting edging slightly earlier than the other or are loading it in a way to make it track a tighter radius. You may not feel like it while you're performing the motion (it's ingrained in you) and it's probably small enough a movement so you can't perceive it, but this is what's happening in reality.
|
|
|
|
|
|
|
|
FAQ
