Forums: Climbing Information: The Lab: Re: [patto] Theory about forces in a 3-legged cordelette: Edit Log




BetaRock


Jun 25, 2012, 4:59 PM

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Registered: Jun 25, 2012
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Re: [patto] Theory about forces in a 3-legged cordelette
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patto wrote:
I believe John Long did do tests with the 3 legged cordalette. But there was so much wrong with John Long's 'research' that it is hard to know where to begin.

The two legged cordalette is trivially easy to equalise well as long as there a proper 'V' angle formed. A three legged cordalette is almost impossible to get perfect but in my experience I can get rough equalisation without too much difficulty.

First, I don't think John Long himself was involved in the Sterling tests to which I'm referring. Those tests were performed by Jim Ewing, R&D manager at Sterling Ropes. The statistics were completed by Dr. Lawrence Hamilton and Dr. Callie Rennison.

Second, according to the test summary, they did not perform tests for a 3-legged cordelette rig. Only the 2-legged.

Would you mind detailing the flaws in Ewing's tests? The details of the experiments are laid out in the book and determined that the load distribution across the two legs were dismal: almost 800 pounds difference between the legs in a Factor 1 fall.

This difference in force seems significant to me. Is there debate surrounding how they performed those experiments?


(This post was edited by BetaRock on Jun 25, 2012, 5:03 PM)



Edit Log:
Post edited by BetaRock () on Jun 25, 2012, 5:02 PM
Post edited by BetaRock () on Jun 25, 2012, 5:03 PM


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