Don't have time for a lengthy reply, however, we use a combination of very strong on the primary length and not so strong on each end.

The long, too strong part is sold by Samson Rope, and is called Tenex. We use 1/4 inch for most gliders. Each end has a short section of 1/4 inch Polypropylene (about two feet) serving as the required weak links. No kind of knots are permitted.

The ropes used on the ends as weak links must pass a breaking strength test using a simple lever arm and weights to verify the rope meets the breaking strength requirements.

A major problem is the quality of the rope. In some cases the brand new rope has broken strands, or knots on individual strands, which causes the rope to fail during breaking tests.

Probably a good magazine article.

Tom Knauff