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Slack line anchors !?!

widewetandslippery

9-May-2012
2:02:00 PM

Man I went to a Catholic boys school and they never told me about sins 10 & 170. Do tell more.

Olbert

9-May-2012
2:48:18 PM

On 9/05/2012 One Day Hero wrote:
>Oli, I'm disappointed! You feeling ok? Seems like you've gone a bit pussy
>about this stuff. I'm gonna have to sort it out myself.

I was giving the benefit of the doubt as in this instance he didn't seem too far wrong.

>
>Firstly- "apparent weight"?? Fuch that, don't use made up terms!

I figured this might be something that is used in rigging because it might be easier to understand for some people even though it's wrong (especially when industrial safety things are rated in kilograms and not newtons). Since I'm not a rigger I wouldn't know.

>There
>is the "mass" of the slackliner, and there is the "force" which is exerted
>due to the "acceleration" of the slackliner. At no point is it helpful
>to conjour an "apparent weight"

I feel it might be helpful if all your rated strengths are in kilograms. Climbing gear is not...so in this instance, yes, it is fairly useless.

>Next- Nobody knows what the maximum force will be when the slackliner
>falls off the slackline.........this is way too complicated to work out
>without measuring stuff. 5g acceleration seems too high to me, but in order
>to work it out you'd need to know the; length of the slackline, spring
>constant (if it behaves like a simple spring), how quickly it rebounds
>to its neutral position once unloaded (when the slackline dude pitches
>off, the line will very quickly return to being straight, so his freefall
>will be a lot shorter than the length of his leash).

I thought about trying to do that physics but I figured there would be a bunch of suppositions which would have a large bearing on the outcome.

Also in reality each variable most likely has a large range it could reasonably be (length of slackline, unloaded tension of slackline, spring constant of material, length of leash, mass of slackliner, length of ADT sling, distance between ADT bolts, to name the ones I can think of now).

So I decided not to do the 'first principals solution'. I figured I would reverse engineer Cool Hand Lock's solution. His suppositions seemed fairly reasonable to me at a quick glance (I could probably be won over by a good arguement as to why any or all were bullshit.)

Most of his solution seemed fairly reasonable, if you ignore the ADT bit and the 'apparent weight bit' and the very last bit about the force being 2400kG instead of 1200.

>Death Triangle- It depends! The force on the bolts is dependent on the
>angles in the triangle (ie, how long the sling is), and may vary anywhere
>from 0.7xload up to infinity (on each bolt). It is pretty funny though,
>listening to clowns bidding at the "correct answer" without any fuching
>clue as to how to work it out.
>
>My feeling is that during his rigging course, Cool Hand Lock has been
>taught a bunch of boofy rules of thumb, by a bunch of large boofy riggers.
>Although the numbers spat out at the end aren't that far off this time
>(if you buy into the bullshit assumptions), the process is utterly kooked
>and will produce very wrong results most of the time! On the upside, the
>riggertards seem to have gotten the trig across correctly, which is surprising.
>
>Oli, get your game face on next time, or start looking for another job!

Sorry sir. Yes sir. I will do better next time sir.

One Day Hero

9-May-2012
3:41:01 PM

On 9/05/2012 Olbert wrote:
>
>I figured this might be something that is used in rigging because it might
>be easier to understand for some people even though it's wrong (especially
>when industrial safety things are rated in kilograms and not newtons).
> Since I'm not a rigger I wouldn't know.
>
Yeah, they convert all forces to the equivalent (static mass x gravity)........not the worst idea in terms of visualizing things. However, it goes to shit when riggers try to calculate the forces resulting from accelerating masses.....they end up doing dV/dS instead of dV/dT (it approximates ok for small S, not so well for larger values)

ZERO

9-May-2012
4:00:02 PM

I put this link up on a previous tyrolean discussion.
Its pretty cool watching the forces change as you change the angle.
Someone else has done all the Braniac stuff.

http://www.tagsafety.com/library6.asp

Fish Boy

9-May-2012
4:33:10 PM

What's a "kilonewton"?

I keep hearing about it, no idea if it's a big deal though.

widewetandslippery

9-May-2012
4:46:28 PM

I think newton weighed a lot and a kilonewton is a way of expressing it.

Dr Nick

9-May-2012
5:26:41 PM

WWS is on the money....ish. Newton is a unit of force, and a kilonewton is 1000 newtons (like kilometre is 1000 metres).

To give you an idea, 1 kN is the weight of a 100kg mass, or a big bloke hanging. 1N is equivalent to the weight of a 100g mass, or a king size Mars Bar.

You might also see stuff rated in "daN", meaning decanewton. This is 10N, or about the force required to hold a 1kg mass.


ChuckNorris

9-May-2012
5:34:36 PM

You guys are FULL OF SHIT.

There is, was, and only ever will be one Newton.

I'm adding you all to my ignore list.

widewetandslippery

9-May-2012
5:37:11 PM

You fellas keep using so many words.


Miguel75

9-May-2012
5:54:12 PM

On 9/05/2012 Dr Nick wrote:
>....To give you an idea, 1 kN is the weight of a 100kg mass, or a big bloke
>hanging....

Woohoo, that's the weight of me climbing nude;)

widewetandslippery

9-May-2012
6:11:36 PM

4.5lb baby, 98kg man


ChuckNorris

9-May-2012
6:16:54 PM

KillaNudeMiguel (KNM).

Got a kind of ring to it. Hey mr physics (oli) what's the name of that standards bored we apply to to get the name and metric renamed and recallibrated?

widewetandslippery

9-May-2012
6:46:18 PM

Ok I am no mathematician but how can missing naughtswhich equal zero which equal and therfore mean nothing make a difference?


IdratherbeclimbingM9

9-May-2012
6:48:51 PM

On 9/05/2012 widewetandslippery wrote:
>Ok I am no mathematician but how can missing naughtswhich equal zero which
>equal and therfore mean nothing make a difference?

~> The same way that a '.' makes the difference between a simey and a simey. ? ...
☺

One Day Hero

9-May-2012
6:52:02 PM

On 9/05/2012 bomber pro wrote:
>KillaNudeMiguel (KNM).
>
>what's the name of that
>standards bored we apply to to get the name and metric renamed and recallibrated?
>
I remember from highschool that the Frenchies have this "platinum/iridium ingot" which is supposedly the kilogram standard.........probably have to send Miguel over there to bust some heads and let the Frogs know that the new standard is him!

"Yeah? Is that what you reckon, Jean-Clau-de? Well, how would you like to calibrate this?"

"Ah merde! My eyes.......I cannot unsee"


Miguel75

9-May-2012
6:56:00 PM

On 9/05/2012 Fish Boy wrote:
>What's a "kilonewton"?
>
It's similar to a 'fig newton' but contains less fig by volume/ms


Cool Hand Lock

9-May-2012
6:57:01 PM

On 9/05/2012 nmonteith wrote:
>It should be mentioned that the sandstone rock at Brooyar is notoriously
>soft - even worse than most of the Blue Mountains. Had they placed their
>own 10mm bolts? or were they using ones already in place? I hope they weren't
>expansions!!

They are 3/8 SS glue ins, placed close together. Seems they've been placed for slacklining. Nothing wrong with the location. Just undersized and poorly set out.


Cool Hand Lock

9-May-2012
7:05:02 PM

On 14/03/2012 sliamese wrote:
>Do people get that an american death triangle will put about 140% of the
>load onto EACH anchor?

Thanks for the link the to Wiki page. If you got 2 climbers(200kg) and put them on a trianlge rigged like in the wikipedia page. You'd could load the anchors to 140% of the load each. 280kg, as the MBS of most bolts is around 2200kg, although the load could be easily reduced, it would be about 1/8th of the MBS.

would work, does work, but could be easily improved.

widewetandslippery

9-May-2012
7:05:34 PM

at least m9 makes sense


Cool Hand Lock

9-May-2012
7:11:53 PM

prove me wrong:
http://www.wedderburn.com.au/weighing-solutions/crane-scales/msi7200-dynalink-crane-scale

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