On Sunday, December 30, 2018 at 10:02:46 PM UTC-7, John Foster wrote:
I'm seriously looking at a reverse auto tow set-up to cut the costs down when starting up the club and am playing around with design concepts in my head. As far as rope goes, I am really impressed with Dyneema as a rope material, and from what I can gather, Samson Amsteel Blue Dyneema has a breaking strength of 1400 lbs for a rope only 7/64" diameter. That's about the thickness of a string! I can get a spool of it 3280 feet in length. Our runway is about 4,800, so we'd probably need to splice some additional length to be able to utilize the full length of the runway and maximize the height of the launch. Would need to use a weak link on each end though. For this application, would a single axle wheel like a motorcycle wheel rim work better for the pulley, or would something like the Cotswold design work better? The rope wouldn't have the extra mass that the piano wire did that they used in Cotswold.

1/8" for 2400lbs. Not sure is the small diameters are easily spliced buy I have a spool of 1/8", so well let you know.

You might get away with a 14" wheel. I wouldn't bother with a motorcycle wheel.

Have to grok on this a bit.

Frank Whiteley
Been there, done that