Question on zip lines

[Jeremy9]

I was just wondering if anyone knew how to figure the weight you are putting on your anchors when zipping a piece.

 

[RogerM]

There's a "rope angle physics" spread sheet floating around in the archives somewhere. It allows you to input different weights as well, Mr Adam's might be able to link it for you.

 

[Blinky]

That's some complex math. The loading changes as the piece slides and the rope angles change. It's good to figure out the basics but generally use big safety margins.

 

[Mahk_Adams]

[ QUOTE ]
That's some complex math.

[/ QUOTE ]

Very.

Very.

In the words of the late Peter Donzelli, who was a Certified Arborist and an engineering professor:

[ QUOTE ]
Many people have asked me to try my hand at this calculation.
As much as I have tried, I don’t yet understand it to my own
satisfaction, and don’t want to pass off bad information.
. . . [T]he initial rope tension and stretch (engineers would talk
about rope stiffness, the ability to resist stretch) . . . is the key
to solving for the forces in a speedline. Problem is that it now
becomes more complicated than just vector diagrams; there are
differential equations involved. Just as important, though are
some experiments to validate the equations.

[/ QUOTE ]


Bearing that in mind here are two articles on setting up a speedline:

http://www.treebuzz.com/pdf/speedline_variations_1.pdf

and

http://www.treebuzz.com/pdf/speedline_variations2.pdf


Here are some links to past discussion:

http://www.treebuzz.com/forum/showflat.php?Cat=0&Number=23165&page=0&fpart=3&vc=1

and

http://www.treebuzz.com/forum/showflat.p...h=true#Post8017

See also the ISA's Art and Science of Practical Rigging workbook and DVD, although that doesn't really address the issue of the forces involved.

If the tree is at all suspect, back it up with a second line.

 

[TheTreeSpyder]

This assumes a horizontal line, the actual equations will be by how the rope is inline with the force of gravity(vertical).

Rope Angle Calculator

And then adding an extra leg of force for a Double whip tackle spread: Spread DWT

 

[Jamin_Mayer]

[ QUOTE ]
This assumes a horizontal line, the actual equations will be by how the rope is inline with the force of gravity(vertical).

Rope Angle Calculator

And then adding an extra leg of force for a Double whip tackle spread: Spread DWT

[/ QUOTE ]

As always. Good work.