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REAL jump/landing building

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mer-man
Posts: 1079 - Karma: 10
What are the fundamental aspects to proper jump building? What is the general formula for speed/slope on packed snow? What is the proper aspect ratio in-between a jump and landing? What is the smoothest ratio between a jump and landing? How do you calculate the parabola of jump with a given speed?

Someone must have the answers to these questions?


Nov 27 2011 9:11PM
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Ski_ThEast
Posts: 1676 - Karma: 272
in terms of speed you just gotta feel it out then send it.
Nov 27 2011 9:12PM
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james6345789
Posts: 4763 - Karma: 461
I think most people just kinda pile snow, shape it a little bit, and hope for the best...
Nov 27 2011 9:14PM
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steezy.stew
Posts: 1137 - Karma: 568
Does anybody actually think into it that much? I thought the general mindset was just fuck it and huck it
Nov 27 2011 9:14PM
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-=---=-=-=-
Posts: 424 - Karma: 7
I'm sure the Olympic committee has this figured out already..
Nov 27 2011 9:17PM
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mer-man
Posts: 1079 - Karma: 10
No because when you are building a jump, you need to establish a realistic speed that you can achieve every time. Once you calculate your general speed you need to build a jump that will accommodate your speed. I am building the jump/landing out of 70 odd yards of topsoil before the snow comes, so I can't just see how fast I'm going.
Nov 27 2011 9:18PM
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Willgum
Posts: 3254 - Karma: 3,066
I think big ass mountains like Breck and huge competitions must put some thought/calculations into it since you cant fuck up on the scale they're dealing with. Theres probably a veteran park buillder on ns somewhere who can give you some number5.
Nov 27 2011 9:19PM
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coldcuts69
Posts: 3718 - Karma: 1,888
yes. and im assuing based upon his icon the OP is canadian. this means he can figure his own shit out cause canadians are cool
Nov 27 2011 9:20PM
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mer-man
Posts: 1079 - Karma: 10
WORD, what I'm hoping for.
Nov 27 2011 9:21PM
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Guard_Puma
Posts: 344 - Karma: 82
There is definitely some very basic physics that go into jump building, at least for quality jumps. Simple vector equations that take into account the distance in X you want to travel , the velocity in X and Y when you take off (corrisponding to the take off angle and speed) and when you land (X and Y velocities when you hit the deck). I
Nov 27 2011 9:21PM
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mer-man
Posts: 1079 - Karma: 10
exactly, there must be some basic formulas that can really improve the way a jump feels. I have seen some parks which have jumps which scream 'wtf?'
Nov 27 2011 9:25PM
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west-coast
Posts: 985 - Karma: 204
45 degrees will shoot you the farthest and highest, and speed has a direct correlation with clearing distance so it would be extremely easy. talk to a physics teacher and they will explain in deeper context
Nov 27 2011 9:26PM
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polmei
Posts: 410 - Karma: 1,463
im sure jon olson could answer this question.


the man to ask really is David Ny how built the jumps for the Olympics, the Jon Olsson Invitational, Swatch Skiers Cup and the Arctic Challenge.
Nov 27 2011 9:30PM
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Ski_ThEast
Posts: 1676 - Karma: 272
oh i was referring to just a backcountry booter or something i mid-read your op
Nov 27 2011 9:31PM
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ForeverYung
Posts: 8385 - Karma: 2,060
thats what i do
Nov 27 2011 9:32PM
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HeathR
Posts: 4359 - Karma: 1,382
I have done 6 seasons of park crew, and its quite surprising that no formulas were ever used. Even when we built the Burton Open course in NZ and a 90 ft jump, no math or calculations were done. To figure out the speed for the 90 footer you just make your best guess and go for it. Its all done using the experience and feel of the cat driver and crew. After you have built a ton of jumps you just get a feel for it. You test it, and then make tweaks. I have measured takeoff and landing angle but its usually just done by feel. I like the landing to be about 5 degrees steeper then the takeoff but it kind of depends on the style of jump. You could use physics and speed guns to figure it out but there are so many variables that it simpler to just build it.
Nov 27 2011 10:47PM
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kamron_708
Posts: 944 - Karma: 1,129
What about level 1 or stept guys. They are for sure aware of how to build a 110 foot jump like the sun valley one. That'd be fucking terrifying just like how waldo went way too big
Nov 27 2011 10:55PM
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HeathR
Posts: 4359 - Karma: 1,382
The speed it takes to make it to the landing of a jump is a extremely variable thing. It gonna depend on the takeoff angle and the style: step down, step up, step over, and true table all take different speeds even if they are the same size jump. As stated before in a simple physics equation 45 degrees is going to give you the maximum distance, however this is way to steep for a park jump. Then you have wind, snow conditions, temperature, ski length, wax, weight of the skier, how baggy clothing is, how hard you pop, if you lose speed when you spin, etc. This is why I can be really difficult to take physics from the classroom and apply it to the real world.
Nov 27 2011 11:01PM
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skiEER
Posts: 4089 - Karma: 79
this is why they have kids like you to test the jumps no nobody important gets hurt
Nov 27 2011 11:37PM
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Rob.
Posts: 189 - Karma: 16
It can be done by physics for sure, but I doubt it often is.

The basic physics: http://en.wikipedia.org/wiki/Trajectory_of_a_projectile (I haven't read it, but I'm sure it will give a good enough description)

This requires a bit of calculus if you want to include air resistance, which is a must for gaps, along with some empirical data about coefficients of drag, etc. This method also neglects any "pop" on take-off.

I've always thought about making something to define the "perfect" landing slope, where no matter your take-off speed for a given take-off angle (above a minimum speed), the angle at which you met the ground on landing would be less than, say, 10 degrees. It would be useful, but in reality very difficult to adhere to. For city jumps it would work fine (neglecting size constraints), but on mountains it's largely a matter of working with what you have.
Nov 27 2011 11:51PM
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BlakeG
Posts: 1450 - Karma: 1,030
i think that the pop of a skier would be a variable that would be hard to calculate since it would differ from person to person. Also it would be simply hard to calculate(unless im a fucking idiot and i dont know how to do this) so i think that mayeb 30 degrees would be a good angle for takeoff
Nov 27 2011 11:57PM
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Rob.
Posts: 189 - Karma: 16
It is basically the added vertical component of their take-off velocity. Not too difficult to find using even a medium- to high-frame rate camera. It would vary from person to person, one time to another, one jump to another, certain snow conditions to another, etc. Realistically, you can't control everything.

Wind is a factor which is just as important. Any relative headwind component, you will travel further. In this case, the best take-off angle (for distance) would be less than 45 degrees. Similarly, if you have a relative tailwind component, then the best take-off angle (for distance) would be greater than 45 degrees. These effects depend on many other variables, including your frontal or wetted area, coeff. of drag (which is basically a function of your shape and exposed surfaces, including how baggy your clothes are), how fast you are spinning (if you are) and some properties of the air. Crosswinds have an effect too.

Friction between your skis and the snow is there too on the lead-in. Can't forget about that, but at least it doesn't apply after you leave the ground.

When you start digging into the theory behind this, you really need to use some good judgement and estimations. So in the end, you end up with a good guideline but still nowhere close to an exact answer.

Sadly, these are some of the types of things you day dream about when going to school for aerospace engineering.
Nov 28 2011 12:33AM
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mer-man
Posts: 1079 - Karma: 10
Ya same with COC this year. Its just a really experienced Cat driver that feels everything out. I can def see the logic behind a 5degree steeper landing.
Nov 28 2011 8:14AM
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skifoo
Posts: 1396 - Karma: 45
making small jumps its just simple. you can see it by eye if you can do it or not. But building like JOSS kicker, Thats just speechless
Nov 28 2011 8:40AM
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Loco-Deer-Slayer
Posts: 1401 - Karma: 701
shit man when I go skiing I'm trying to escape from school, who uses calculus/physics to build jumps?
Nov 28 2011 9:01AM
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coldcuts69
Posts: 3718 - Karma: 1,888
park builders/designers? i really have no clue though.
Nov 28 2011 9:04AM
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Master_Debater
Posts: 1211 - Karma: 225
Bricks. Bricks of white. and lots of em. stacked into a jump and shaved down.
Nov 28 2011 9:55AM
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theabortionator
Posts: 52146 - Karma: 168,471
It's not that hard to get it pretty close if you know what you're doing. Just gotta visualize that shit.



Nov 28 2011 10:08AM
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theabortionator
Posts: 52146 - Karma: 168,471
For sure. Then it comes down to do you trust yourself. Better an employee than some random gaper. Also you can always tweak it a little if needed.



The bigger the jump the more it has to be done right. I def enjoy checking out all the pics/video of joss every year on here.
Nov 28 2011 10:11AM
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skibum_mark
Posts: 515 - Karma: 567
When choosing a location for your jump you should make sure you cannot over shoot your landing. If there is too much vertical drop in. make a starting point with a gate or some sort of a sign.

Try not to make the gap bigger than the landing.

In terms of shaping your dirt work you should push a mellow landing. You can always add more snow to make it steeper. The cat can only groom to a steepness point before it starts slipping and doing a poo job.

I hear for testing test big money shot jumps, Jon Olson know how to build them for it.. you shape the slide of the landing like hips.
Nov 28 2011 10:55AM
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theabortionator
Posts: 52146 - Karma: 168,471
For bigger jumps at bigger mountains they winch the landings. Then you can get it as steep as you need it.
Nov 28 2011 10:59AM
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Elg
Posts: 2998 - Karma: 3,881
Whats going on in here?! Nothing but serious posts?

I sure hope there is some math going into building the really big jumps they use for shoots and comps. I skied down the arctic challenge course last season,without hitting the jumps off course, the night before the comp. Those jumps were huge, and i don't think they would send professional athletes to hit them without knowing they would clear them, or knowing that the landings matched the take-offs when it comes to angles.
Nov 28 2011 11:04AM
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skibum_mark
Posts: 515 - Karma: 567
Really? Blackcomb has pretty big jumps and im pretty sure they dont winch. It sounds pricey... Winch cats aren't cheap and if there is no anchor then your going to need another cat and operator.
Nov 28 2011 11:30AM
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theabortionator
Posts: 52146 - Karma: 168,471
Idk man. Just saying that most large operation winch their big jump lines. And I would be really surprised if a large mountain with steep terrain that they groom didn't own at least one winch cat.


If you want a really large jump and a steep landing it's really the only way to go.
Nov 28 2011 11:44AM
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Elg
Posts: 2998 - Karma: 3,881
how exactly do tha use the winches? Is it just for pulling the snow cat up the steep parts?
Nov 28 2011 12:34PM
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J_MAC
Posts: 572 - Karma: 127
yaaa merman i did my graduating math project on the physics of a jump so if you really want to calculate it out ive still got all the equations and know all the variables
Nov 28 2011 12:45PM
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Stickity
Posts: 7750 - Karma: 769
false
it's about 54 i think because of drag
Nov 28 2011 12:48PM
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zagfan5
Posts: 2608 - Karma: 144
pulling up or slowly going down. its just there so the cat doesnt flip. and for the extra power. im sure the cats have enough horsepower to get up a steep slope like that, its just for the extra safety, and you dont have the strain the cat as much if its anchored.
Nov 28 2011 12:57PM
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cow.
Posts: 416 - Karma: 200
in my experience, people build jumps skinnier than they should be, and don't let them sit long enough afterwards, to let the snow harden. (it really does harden) leave the jump like 2 hours minimum, and like a day ideally to get a solid jump.

the only question i can answer intuitively for ya is the smoothest ratio one. it'll be smoothest when the landing slope is parallel to your instantaneous velocity vector as you land.



just out of curiosity, why the heck would you ever want t know this? you gonna hike up somewhere with blueprints, measuring tape and a calculator? yearitemang.
Nov 28 2011 2:01PM
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crab_pretzel
Posts: 3919 - Karma: 622
WRONG! highest would be straight up obv, and your statement is only true when your landing at the same elevation as your takeoff which is almost never true for your average stepdown jump

and just to explain why 45 degree=max distance is cuz sin(2theta) is somewhere in the numerator of the horizontal range formula. the greatest value you can get out of that = 1 when its sine of 90, anything more or less than that in degrees will be less than one. so 45 is what gets you 90, and when everything else is constant thats gonna be the max horizontal range (distance).

and OP i have one answer for you in the words of my old physics teacher: PHYSICS!
Nov 28 2011 2:58PM
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shredsox
Posts: 66 - Karma: 14
Lots of great answers already. HeathR pretty much nailed it - the countless variables make the math extremely difficult. A good builder can see speed, and also the relationship between the jump and landing angles. Build it, test it, then make the minor tweaks to get it perfect. Then continue to evaluate the jump daily and make changes as needed.

Winch Cats: Are used nightly in 22ft pipes, most 18ft pipes, and occasionally by jump builders when needed. The winch is really more about traction then horsepower. All the horsepower in the world is useless if the tracks of the cat are spinning. The winch does give you more power, but mostly it balances out the weight of the machine and keeps it from sliding and the tracks from spinning out. The more traction you have the more snow you can push/pull uphill.


Nov 28 2011 4:01PM
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mer-man
Posts: 1079 - Karma: 10
I have a 100meter hill infront of my house. I built an 8ft high tower on top of the hill that add 15ft of about 70degree angle. The tower also has an insulated interior that is complete with heat, macbook and shred-shack beats. Also there is a secondary room that comes off the tower which is a couch/lounge area. The reason for being choosey about the angles is that it is going to be almost 35ft, and the nature of the landscape means that you are jumping over a reversed tilted L shape. Don't know if that makes sense lol but needless to say its going to suck if you fuck it up. I am building it with a kabota so I have the opportunity to really sculpt everything which is why I want to employ some physics that will ensure the jump has a good flow. With the possible addition of a rope tow, it could be epic stoke time! Mostly it came to this from riding the shit ass high impact jumps all around my area in quebec. I spent the summer in whister digging for wssi. The insane that went into the jumps at all the camps translated into such an difference it was like black and white. Being back in quebec, I just dont wanna fuck it up bla bla bla
Nov 28 2011 7:25PM
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Trace.
Posts: 1460 - Karma: 635
I'm not sure if It's dead but I bet someone in the park builders cult could give you some help on this too
Nov 28 2011 9:27PM
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FerrisBueller
Posts: 8280 - Karma: 5,173
this
Nov 28 2011 9:32PM
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theabortionator
Posts: 52146 - Karma: 168,471
Oh believe me, it's dead.

Used to be decent a few years ago.
Nov 29 2011 1:21AM
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snomaster
Posts: 3346 - Karma: 5,776
I just scrolled this whole thread to see what you posted here.
Nov 29 2011 1:35AM
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ASkierNamedJaymz
Posts: 1209 - Karma: 341
dont want to make my own thread for this... but do you have any suggestions for building a wall ride/stall jump. one that goes straight up to your feature. i think maybe my transition was too short or something but my skis tips kept digging in. Help?
Nov 29 2011 1:38AM
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theabortionator
Posts: 52146 - Karma: 168,471
This has nothing to do with the op. Give it more transition get your weight back. solved
Nov 29 2011 1:46AM
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bleevus
Posts: 1308 - Karma: 2,049
yeah the renter at my parents old house designs the jumps for the dew tour.
Nov 29 2011 9:08PM
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DBL
Posts: 1405 - Karma: 2,218

Brimacombe Park Build from Fresh Pressed Productions on Vimeo.


Nov 29 2011 9:32PM
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Billups
Posts: 3960 - Karma: 329
This is the guy you want to be listening to. I know when we build our stuff, there are no formulas, no standards. We look at what we have to work with, what kind of feature we wan to build, and how big we want to build it. Different features are going to have different kinds of landings and take offs.

Step downs benefit more from steeper landings, and step overs with shallower landings. Your basic table top works best with a take off and landing within a few degrees of each other. But i second what others are saying in that the best jumps come from a trial and error process combined with the experience of building stuff.
Nov 29 2011 10:10PM
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