After my friction work I'm ruined. I see 1/(1+1.2)x300 = 137 lbs in one rope leg and 1.2/(1+1.2)x300 = 163 lbs in the other leg, and the down leg gets 137 lbs / 1.2 = 114 lbs going down to the portawrap. Tension ratio of a rope going around a pulley like shown is 1.2. Block sling sees 137 + 114 = 251 lbs. Magic of aerial friction. Top of tree sees 137 + 163 (i.e. 300) + 114 lbs down leg = 414 lbs not 450. Magic of aerial friction again.
Top block creates useful aerial friction by reducing the down leg value. The "with the log" pulley/device kicks up the load at the stationary rope tie point on the trunk while contributing to lowering the down leg tension. Useful to know if you sub in a more active friction device for the upper block or at the log. Biner comes to mind.
I'm ruined in the same way that arborists can't enjoy a walk through a park without sizing up how they'd climb all the interesting trees. Picking optimal tips, routes etc in their mind.
Carry on. I should have put up a nerd alert for this post.
Top block creates useful aerial friction by reducing the down leg value. The "with the log" pulley/device kicks up the load at the stationary rope tie point on the trunk while contributing to lowering the down leg tension. Useful to know if you sub in a more active friction device for the upper block or at the log. Biner comes to mind.
I'm ruined in the same way that arborists can't enjoy a walk through a park without sizing up how they'd climb all the interesting trees. Picking optimal tips, routes etc in their mind.
Carry on. I should have put up a nerd alert for this post.
