Well, the monsoon paused; so the 2 10year olds and i set this up.
We have a 3500# and 2500# Dynos; as previously referred to; some 1/2" arborist lines ~7,000 tensile, and a come-a-long. We use the comealong as input force, to have something really readable on the scales/ not splitting hairs of a few pounds on these tiny face readouts; and more fun/ more power to boggle lil'minds (self included); to cook more imaginations as to the possibilities etc. Working in input range of ~250# for readability and yet staying within confines of safe working practices/ SWL.
We used DBY/bowlines rather than butterflys; as i've often thought short bowlines to place less side pressure/ friction on running ropes, than long eye bowlines or butterflys. i used multiple eyes with single line reeved thru, rahter than multiple lines ran thru same eye. We even (ab)used some kind of Lehman concotion of single eyed DBY in bight for this.
We found the 1.6x as fairly realistic for a theoretical 5x setup. But, quickly 'pinging' or sweating line, then relaxing would allow both scales (input and output) to read lower values, then cranking come-a-long more would get us up over 2.5x input to output ratio. Even just vibrating lines allowed force to equalize between the legs of pull more, to allow less effort input, to a higher output. Such input/output reads is why i have 2 Dynos.
After tightening input comealong to ~200#; and getting a readout on output Dyno of ~500#+; could bend the line comealong pulls; to a perpendicular angle by hand, to get ~700#. While grabbing all legs of lines and bending them perpendicular to the tension force flow thru them, rendered ~850#.
After such manipulations, that allowed higher tension into the legs of pull closer to output than input end; the same friction that reduced the ability to tension those lines with come-a-long; now seemed to help hold same tension, for slightly higher readings on output.
Placing 1 pulley in the system; did better as theorized, being placed on the input end, rather than output; but seemed to reduce the power of the sweating strategy somewhat. It's looking to rain again; but in a hurried fashion, on 1 test of several runs, that is whut we got.
Bending and 'rattling' lines on this type of friction setup; is a usual strategy and style for me. The more friction on bends, the more useable this strategy is i think. Also the final bending for force is a very powerful force.
A lot of times i take the linear tightening; even with some temporary sweats and line rattlings; to be not the real tightening; but stiffening the line. Then, bending the lines in final stage (for tie downs etc.) as final stage of tightening. This bending the more stiffer/tighter lines from the stage 1 linear tightening, gives higher leveraged return when bent.
MOst of the high, high leveraged power of line bending is in the first few degrees from perfectly straight. So, a tighter line that resists bending more, bends less, and is in a higher leveraged multiplier position; so gives higher leveraged return from the bending force.
i wrote the
Bent Line Force Spreadsheet allows manipulation of the angles and pressure at bend (to read out pressure at termination/anchor) by the user.
In all fairness, returns of 1.6x - 2.5x from a theoretical 5x system might not be considered high. But, then this is just on the compression strategy of rig use; but if used for lowering, keeping tension or relaxing tension slowly; i think we would have the 5x + these friction factors that fight us in compressing jig.
Taken to knot lacings of similair bends, forces, friction on self etc. i think we have lots of power in roundturn; but not as much increase in utility going to double round turn, then to coil when trying to feed line tension in; but then lots of help given by the increased turns in holding the line tension they've purchased.
Spock Out;
