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28 off from a heli at 100ft

gator1gator1 Posts: 591 Crazy Baller

We filmed one of team Spokane stroking 28 off. Tried pretty hard to keep the respective position of Heli to skier constant to allow the tech heads to get a good consistent look at the path. Anybody want to bet what differences there will be between this path and 38?


  • webbdawg99webbdawg99 Posts: 1,067 Mega Baller
    Was the 1/3 side the onside or offside? Turn radius was much more consistent on 1/3. 2/4 you could see angle rapidly increased at the finish of the turn.....except for 6 ball of course.
  • Than_BoganThan_Bogan Posts: 6,630 Mega Baller
    Man you're doing some cool stuff right now @Gator1! Trying to figure out how you're making time!!

    Anyhow my prediction: The -38 path will be slightly sharper out of the buoy, cross the centerline slightly earlier, and have a slightly straighter looking path into the ball. Another way of saying it is that will bend a hair closer to a square wave.

    If that doesn't happen, that's when I'm going to get really interested. :)

    Well actually, I won't have to change my thinking much if centerline-earlier thing is untrue, because of course a skier who is capable of running -38 is going to run -28 far ahead -- he/she is not taking the easiest path, but rather the lowest-risk path. These are potentially quite different. Indeed, most of us focus on skiing our early passes "just as hard" even though that is not necessary just to complete.

    If you compare someone who can just barely run -28 with someone who can just barely run -38, THEN I'd really expect the earlier crossing for the -38 guy.

    My theories are moderately well-informed, but that doesn't mean they're right! Some data is always interesting.
    Nathaniel Bogan -- GUT Padawan
  • gator1gator1 Posts: 591 Crazy Baller
    @Than_Bogan I'm in a travel heavy mode right now, following 6 weeks down time waiting for scoped knee to heal, got a grand total of 11 passes so far this spring. Going nuts and killing time while sitting in airports. Fly two days for a 1 hour meeting. Travel is so glamorous.
  • gator1gator1 Posts: 591 Crazy Baller
    @webdawg99 he's left foot forward.
  • bogboybogboy Posts: 699 Solid Baller
    @gator, exciting Video & perspective. my guess is the shorter the line, the farther up on the boat the skier is in the turns. Good luck with your recuperating.
  • jlittlejlittle Posts: 257 Baller
    The difference between this and 38 is... if this guy runs 38 I'm taking him out and buying him a lap dance :-)
  • xratedxrated Posts: 506 Solid Baller
    @jlittle if that involves a classy establishment I'm going to Compton just as soon....ahh heck I can't even run the course so you are safe.

    @gator1 cool perspective.
  • LkSamm196LkSamm196 Posts: 75 Baller
    You need a couple different cameras/ know like Travis Rice does it.
  • JJVDMZNJJVDMZN Posts: 128 Baller
    The paths will be the same, or very close to the same
  • skinutskinut Posts: 424 Solid Baller
    @gator1 where is that lake?
  • cragginshredcragginshred Posts: 713 Crazy Baller
    Sweet thanks for sharing this!
    Vapor pro 2017
  • SethroSethro Posts: 293 Solid Baller
    That is really cool! Seems like he's pretty far past the ball when he hooks up and heads across course, but is still there in plenty of time at the next ball.

    It's official, I need to come to Washington if for nothing else to get a ride in your helicopter. Maybe you could fly down to CA and pick me up when I'm there in two weeks.
  • gator1gator1 Posts: 591 Crazy Baller
    Anytime @Sethro‌
  • DustyDusty Posts: 315 Baller
    Hard to tell who that skier is but I have a suspicion... Must have filled his tag already...?
  • jlittlejlittle Posts: 257 Baller
    @Dusty Funny lol... Yes, after a two year drought he finally fed a long beard a face full of #6s April 25.
  • DustyDusty Posts: 315 Baller
    @jlittle- -38 will go down just like -35 did. "you don't need it all, you just need enough"... if I might be so bold...
  • gator1gator1 Posts: 591 Crazy Baller
    @Dusty‌ , two sets in a row, we're only two balls away from the stateline. Damn, I can almost smell the desperation and stale beer in the carpet. Can't wait for our boy to get it done and get me back to the home of my youth.
  • jipster43jipster43 Posts: 1,434 Crazy Baller
    I really ought to jump in the truck and get to those Moses Lake tournaments this weekend. The logistics are cramping my style at the moment, but it would be cool to watch @jlittle 's first tournament 38 go down.
  • ColeGiacopuzziColeGiacopuzzi Posts: 453 Open or 55K Rated Skier
    I actually happen to have a video of myself at 38 off from above, kind of cool to see if there's comparison @gator1‌
  • ColeGiacopuzziColeGiacopuzzi Posts: 453 Open or 55K Rated Skier
    edited June 2014

    This is 38 off on memorial day weekend, this is also the Lake that the free Pacific Slalom Clinic will be held on with the Wilson Bros demoing Radar Skis on June 27th so hurry and sign up!
  • gator1gator1 Posts: 591 Crazy Baller
    @Colebrah‌ Thanks! very cool. My Heli got conscripted to go dry cherries so we were in a hold mode.

    Shape is basically the same between 28 and 38: Two straight lines with a hook at the end. Easier to see at 38.

    From hookup to a little past the whitewater at about 40 degrees (acceleration), then sharp 15 degree turn, then straight line while coasting to turn. Basic difference between 28 and 38 is angle of the acceleration line and angle of the coasting line, and sharpness of turn at ball.

    amazing what perspectives show. Bears no resemblance to any pendulum. And, therefore, I submit to the BOS intelligensia, pendulum physics as a mathematical model to discuss speeds and accel is a waste of time.

    I'm mesmerized by straightness of those two lines. Just like that recent video of AM gates from the side perspective. Makes it very easy to model speeds from a visual.

    BT dubs, nice pass brah.
  • Than_BoganThan_Bogan Posts: 6,630 Mega Baller
    This is awesome visual data! SO COOL!

    The statement "bears no resemblance to any pendulum" goes a little too far. At some point I hope to have time to explain why (with charts even!). I may start by emailing you directly. Possibly not today; we'll see.
    Nathaniel Bogan -- GUT Padawan
  • ToddLToddL Posts: 2,824 Mega Baller
    The distinctness of the two paths at different angles just means the skier is pretty efficient at creating space before the buoy.
    -- The future of skiing depends upon welcoming novice skiers regardless of age to our sport.
  • jipster43jipster43 Posts: 1,434 Crazy Baller
    @jlittle I heard somewhere out there a stripper is a little richer!
  • SkiJaySkiJay Posts: 2,314 Mega Baller
    @gator1 I've noticed the same thing from forward mounted GoPro footage. The ski goes straight, edge change, straight, turn, repeat . . . . But the handle scribes a perfect arc around the pylon like a pendulum. Herein lies a lot of the complication in skiing. The energy source is scribing arcs while the ski is tracking relatively straight lines, and the skier in between these two things has to keep them efficiently connected. It has to be one of the most complex moves in sports. ... Your ski should be your dance partner, not a wrestling opponent
  • gator1gator1 Posts: 591 Crazy Baller
    @SkiJay‌ There are a couple of things I've learned from these videos: When people speak of the ski "grabbing angle" and "building angle to the wakes" I'm convinced they are just kidding themselves. It may be the ski holds the straight line we see with less effort. And, in the category of "something actually useful to getting better" I'm convinced these vids prove you will add no angle once the arms go straight and the load comes on. Which kind of validates the whole patience, finish the turn, complete your rotation, blah blah.

    Maybe the razor 14 or whatever Horton tested awhile back is different, but I think all other skis with the three part rocker prescribe this straight line due to their shape.

    And, at the risk of getting overly into the realm of rocket science, the handle swings an arc back and forth at the end of a string of constant length. However, that arc is not an natural, pendulum profile of gravity accelerating a mass. Instead, the skier is providing acceleration to the mass.

    The rocket science boys would say draw a control volume "an imaginary movng box" around the boat, skier and rope. If we assumed drag from the water was the stand in for gravity, put a guy on a saucer out at buoy width, and let him swing back and forth he'd present a decaying pendular motion in the control volume. Lots of drag, so the motion would decay pretty quickly. But, within the control volume pendulum physics would describe the motion exactly.

    But, the box is moving. So the decaying pendulum would have to be mapped onto the bottom of the lake as the control volume passes over the lake at 34 mph. It would not look like a pendulum, neither handle or saucer rider.

    But, there is more. The skier adds acceleration on the "downswing", and deceleration on the "upswing". So, within the control volume, we would not see a pendular path. It would pick up speed too quickly on the "downswing", and lose speed too quickly on the upswing.

    Then, we have to map the artificially boosted and retarded pendular motion onto the bottom of the lake. A real mess that requires a computer and sophisticated measuring devices to analyze.

    And so, after all this physics and human force adding and subracting, which really IS rocket science, the skier path mapped onto the lake bottom is TWO STRAIGHT F--CKING LINES. HOW CAN THIS BE?

    My mind is blown by this. Why does A=pi r squared? Why is the derivative of speed acceleration? Why does f=ma? Not kindof. exactly. WTF! We ski two straight lines. There must be a god.

    Or maybe the fact that I just finished four beer lawnmowing is having an affect.
  • mwetskiermwetskier Posts: 1,337 Mega Baller
    a guy whose knowledge on the subject i trust has told me ' no matter whether someone thinks slalom is related to pendulum physics or not they never seem to consider that slalom is actually a closer model to a * double pendulum *. the rope to the handle being the first pendulum with the pylon as the pivot point and the handle to the skier being the second pendulum with the handle being the pivot point. the action of the secondary pendulum is generally under the direct influence of skiers input '. i copied that out of his email and dont pretend to understand completely what it means.

    but there is one thing he said that makes pretty good sense -apparently those who study pendulum physics agree that a double pendulums behavior is very much tied to its initial conditions. which sounds a lot like the advice of top coaches who say getting wide and far up on the boat for your gate shot sets up your run for the rest of the pass. its seems those coaches often make reference to similarity with a pendulum when their dispensing that advice.
  • gator1gator1 Posts: 591 Crazy Baller
    Nope. As I have written before, the skier's reach can serve to lengthen or shorten the effective length of the rope.

    But, the handle and rope have comparatively no mass. And, they can only impart a resultant force vector pointed at the boat, with no moment. Consequently, the handle does not serve as a pivot point.

    A golf swing has two main pivot points: Shoulder and wrist. The arm can provide a force vector other than one pointed at the shoulder. And the wrist muscles can provide a moment. Thus, the club does pivot around the wrist.

    Entirely different. The rope has no muscles, and the handle can't provide a moment.
  • DekeDeke Posts: 385 Baller
    @gator1‌ so the skiers reach serves to lengthen or shorten the primary pendulum? And, the skier has the ability to change gravity relative to the pendulum?
  • gator1gator1 Posts: 591 Crazy Baller
    @Deke‌ Yep.
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