Vividly realised why you sometimes want steel rope after trying "blondin" - wire-rope is much stiffer than fibre rope. Recovered some discarded crane wire-rope and gave it a try. Right here, you see it...
Some of that angle in the wire rope will be the trees bending inwards a bit...!
(Yes, I also ran a fibre rope between the trees - it was vastly more elastic - it sagged by a huge angle with the same weight)
R Smith, 19.07.2009