On Apr 12, 9:18*am, 150flivver wrote:
Suppose your tow plane has a placard that says "Max Glider or Banner
Weight: *1000 lbs." *You are going to tow a glider with a max gross
weight of 1000 pounds. *Are you supposed to limit the tensile strength
of the tow rope used to 1000 lbs? *The regulation specifies that the
tow rope should be no less than 80 percent and no greater than 200
percent of the max towed weight. *This would allow you to use a rope
that has a strength of 2000 pounds but wouldn't that endanger the
towing aircraft which has the placarded 1000 pound limit? *Would you
use a weaker tow rope or a weak link or would you just tow the 1000
pound glider with the rated 2000 pound rope?

It would be worthwhile to look at the origin of the placard to
determine what it really means.
Example. Schweizer hooks for many applications have a maximum rope
strength specified of 1200 lb. This effectively limits the max weight
of the glider to be towed to 1500 lb based on min rope strength of 80%
of max gross weight of the glider..
The basis of this specification, if I recall correctly, was force on
the release handle.
Rope strength is specified with limits related to the max certified
gross weight of the glider being towed, that is NTL .80 of gross wt
and NGT than 2.0 times gross wt. Weak links can be used, as
appropriate to saty within these limits.
If the approved installation of the tow hook has other limits, they
are in addition to those related to the glider defined limits.
If you are using a hook not produced for towing gliders(there are lots
of home made banner towing hooks made to AC 43-13 which may not be
suitable for glider towing), consider moving to a proven tow hook
installation.
Good Luck
UH