Discussion Topic |
|
This thread has been locked |
Russ Walling
Social climber
This space for rent.
|
|
|
Topic Author's Original Post - Aug 25, 2005 - 08:51pm PT
|
Hi ya'll,
Busted this out of the other thread so we can rave here. Pete? you there? Shack?? Numbers guys??
Anyway, all this math and stuff was starting to make my head spin and with the way the numbers were going, it was anyones guess as to what is really going on. I'm not saying this is the right answer, but it is a start. I'll leave the numbers crunching to those in the know (Deuce??) and show what I found and noted what I guess is happening.
here ya go.. "talk amongst yourselves..."
|
|
Russ Walling
Social climber
This space for rent.
|
|
|
Topic Author's Reply - Aug 25, 2005 - 08:53pm PT
|
Cripes!!! no edit button and I spelled DAISY wrong on the file.... Try this:
|
|
'Pass the Pitons' Pete
Big Wall climber
like Oakville, Ontario, Canada, eh?
|
|
|
Aug 25, 2005 - 09:06pm PT
|
Uh, like, the co-efficient of static friction is HUGELY higher than the co-efficient of dynamic friction.
This is to say, if you just hang the weights there, it takes a helluva lot to get the daisy to move, which you know is not true. Adjustable daisies are EASY to move.
You get a 2:1 lifting advantage. I don't care if you call it mechanical or counterweight, it's 2:1 less friction through the buckle.
Adjustable daisies rock, and I refuse to climb El Cap when I can simply pull myself up using the 2:1 or so that adjustable daisies offer.
[burp]
|
|
Russ Walling
Social climber
This space for rent.
|
|
|
Topic Author's Reply - Aug 25, 2005 - 11:08pm PT
|
The above was mostly to show what a crappy pulley the buckle is/was. But, as to the real test, I sat in a sling on the locked side of the daisy. Pulled on the free end. Magically I went up with some effort. ok... did this about 10 times to get a feel for it. Now, not hanging there I pulled on the fixed end with the same feel as when I was sitting there. Guess what the dyno said? 150lbs. So, when I was pulling on the free end while sitting in a sling I was pulling 150lbs. At 150lbs of pull, I moved up, and I weigh just under 190 right now. I pulled 1ft and moved 1ft up. So I get 150lbs of effort to move 190lbs.
Elaborate???
|
|
'Pass the Pitons' Pete
Big Wall climber
like Oakville, Ontario, Canada, eh?
|
|
|
Aug 25, 2005 - 11:11pm PT
|
Voice of Bob and/or Doug McKenzie:
"That is, like, way too hard after so many beers, eh?"
And besides, unless you are ALSO a mythical internet Superhero, you can't pull 150 lbs. with one hand...
|
|
Russ Walling
Social climber
This space for rent.
|
|
|
Topic Author's Reply - Aug 25, 2005 - 11:22pm PT
|
Better hit the gym hoser.....
Ok, I used two hands, but 10 years ago I'd show you something. (it still only rounds to 1.3 : 1 )
|
|
'Pass the Pitons' Pete
Big Wall climber
like Oakville, Ontario, Canada, eh?
|
|
|
Aug 25, 2005 - 11:48pm PT
|
The gym?
The gym?! Like, take off, eh?
Why, back in the day, I used to do laps on gym 5.10. I tell you, I was bitchin'. I owned a chalkbag and everything.
|
|
deuce4
Big Wall climber
the Southwest
|
|
|
Aug 25, 2005 - 11:58pm PT
|
Nice "everyman's" test, Russ!
We'll be able to get a coefficient of friction for you shortly. Right now I'm too buzzed from Margaritas at a friends.
Your data will give us the static coefficient of friction. We could also use the minimum weight needed to keep the thing in motion (giving it an initial tug) for the dynamic coefficient.
cheers
|
|
Lambone
Ice climber
Ashland, Or
|
|
|
Aug 26, 2005 - 01:42am PT
|
"Adjustable daisies rock, and I refuse to climb El Cap when I can simply pull myself up using the 2:1 or so that adjustable daisies offer."
What happend to walking youself up your etriers?
Oh yeah, you use those stupid Russion things with the hooks...I forgot.
Pull yourself up El Cap all you want, I'll use my good old legs and save my arms for the scary free climbing sections.
|
|
'Pass the Pitons' Pete
Big Wall climber
like Oakville, Ontario, Canada, eh?
|
|
|
Aug 26, 2005 - 07:00am PT
|
My arms?
{Dr. Piton stands, and steps in front of his full-length mirror which he keeps next to his computer. Adjusting his Superhero cape, he grins at himself and raises one eyebrow, as only Dr. Piton can do. [Pete can't] After a few Superhero poses, he raises one arm to flex his bicep and .....
.... oh dear. Not very impressive, unless you like Oscar Meyer wieners. A clattering of discarded Olde English cans can be heard underfoot as the Doc makes his way back to his chair, and resumes typing}
Thank goodness for adjustable daisies.
|
|
Wrathchild
Big Wall climber
Lee NH
|
|
|
Aug 26, 2005 - 10:03am PT
|
"Dr. Piton stands, and steps in front of his full-length mirror which he keeps next to his computer."
Why don't I find that in the least bit suprising...
|
|
Irisharehere
Trad climber
Gunks
|
|
|
Aug 26, 2005 - 10:08am PT
|
You all need Rich Goldstone (rg) here. Math prof, hard-ass Gunkie, and all-round numbers guy.
|
|
deuce4
Big Wall climber
the Southwest
|
|
|
Aug 26, 2005 - 02:10pm PT
|
What we really need is that dynamic coefficient of friction, the minimum weight the two mass system (in Russ's experiment above) can continue movement after an initial tug.
Once we have that, then we can calculate how much additional work needs to be done using the adjustable daisy for a 3000 foot route. Should be significant.
The key will revolve around whether or not the 100 lbf. weight can be put into motion (even for a brief moment) by a 200 lbf. weight on the other side, with an initial tug.
Russ, waiting for your next everyman's test...
|
|
ChrisW
Trad climber
boulder, co
|
|
|
Aug 27, 2005 - 03:47am PT
|
Adjustable daisys are for wusses! and all you Aid climbers are pussys.
(I have been drinking, also)
|
|
Ed Hartouni
Trad climber
Livermore, CA
|
|
|
Aug 27, 2005 - 12:23pm PT
|
It's not just the coefficient of friction...
...the amount of wrapping of the sling around the "pully" is also a factor, as is well known in braking with a belay device (including a body belay). The forces generated in an ideal case increase exponentially with the wraps.
I believe that is a "freshman physics" calculation...
Not being familiar with adjustable daisies I couldn't quite make out the mechanism from Russ' pictures. Anyone have a schematic of the machine?
|
|
deuce4
Big Wall climber
the Southwest
|
|
|
Aug 27, 2005 - 01:34pm PT
|
Yes, what we're looking for is the total frictional force. Well, we got that for the static case, which is 150lbf., as shown by Russ's test above. Still a lot of potential calculations regarding the whole system.
The frictional torque increases with the radius of the pulley, or in this case, the radius of the cam buckle surface that the webbing passes over. In the actual pulley realm, for example, a 6" cast iron wheel running on a steel axle with no oiling whatsoever will always outperform a 3" sealed ball bearing pulley in terms of frictional losses.
Because of the innefficencies of the cam-buckle there's much extra work involved overall, but then the mechanics of the body would have to be incorporated into the efficiency question (i.e. is it more efficient for the body to pull 150 lbs twice, or 200 lbs once?).
Ah well, another hour wasted looking at an obscure problem.
|
|
Landgolier
climber
Arlington, VA
|
|
|
Aug 27, 2005 - 02:35pm PT
|
I vote that Russ takes the text labels off of the picture above and posts it to the "Pictures of your rack" thread at rc.com
|
|
Russ Walling
Social climber
This space for rent.
|
|
|
Topic Author's Reply - Aug 27, 2005 - 02:36pm PT
|
Everyman test #2: (scary in flip flops)
Loaded it up again as the picture:
1. 100lbs on each side
2. added weight to one side as before.
3. at 250 I could just get it to move and stop with a slight tug
4. added 25 more, and with a slight tug, it would move the 100lbs upwards for a few inches or so, and would probably keep going.
5. so 100lbs on one side, 275lbs on the other side, slight tug and the 100 would move upwards, very slowly, but unaided.
6. Of note, the ridges in the webbing add significant drag into the system. they kinda ping as each one goes over the buckle radius. With smooth webbing the results would
probably be a bit different.
Crunch away.
|
|
Russ Walling
Social climber
This space for rent.
|
|
|
Topic Author's Reply - Aug 27, 2005 - 02:39pm PT
|
Ed writes: Not being familiar with adjustable daisies I couldn't quite make out the mechanism from Russ' pictures. Anyone have a schematic of the machine?
Ed, the edge or radius the webbing is running over is about as wide as two bolt hangers, maybe. Pretty much just a slightly rounded vertically oriented edge.
|
|
maculated
Trad climber
San Luis Obispo, CA
|
|
|
Aug 27, 2005 - 02:49pm PT
|
Irish, doesn't Rich lurk? I think I've seen him post here before.
|
|
|
SuperTopo on the Web
|
Let us know!