In article ,
Bill D wrote:

Matt

Yes, dragging a rope will wear it out. The car doing the dragging will also
wear out fairly quickly. Auto tow is like drag racing - it puts a lot of
strain on a car.

Of course, start-up costs for auto tow are lower than a winch which makes it
attractive but in the medium term (Say two years) a winch is much cheaper to
operate. There are about 1500 clubs worldwide which use ground launch but
only a handful use auto tow. They've found a winch is quicker, cheaper,
safer and gets the glider higher using less space.

By the time you've replaced a few ropes and tow cars, a winch starts looking
pretty cheap.

Yep, we did that. We did the pulley ground launch until the club's
founder, Glen Lawler, built the "Eagle Winch". We happily used it for
several years before a change if airfield made winch use untenable
(crossing runway, not enough runway length). Last I heard, the winch was
at Philly Gliding Council. I miss it. We once launched half a contest
grid with it. The other poor, benighted sods without a ground launch
endorsement had to suffer aerotow.


Speaking of Glen's winch, it had a wide drum requiring an active level
wind mechanism to lay the line on evenly. Glen's level wind was a neat
bit of engineering involving a slotted bar that cammed the guide back
and forth across the drum. Have seen some pretty expensive winches that
had level winds mechanisms that did the job, but were clearly not as
precise as Glen's. Given that, if designing a winch, I'd go for simple
with a large diameter drum that would not need an active level wind.