On Wednesday, October 7, 2015 at 6:06:34 PM UTC-5, Dan Marotta wrote:
As promised, the following clip was copied from raw film shot for an
ESPN show, Secrets of Speed.* The ground launch begins around 30
seconds into the clip but I left the low pass just for fun.* This
shows what happens to the tow car when the glider (me in my LS-6a)
pull too aggressively at the top.



https://www.dropbox.com/s/k9a4v2wbg9...aunch.mp4?dl=0




On 10/6/2015 9:35 AM, Dan Marotta
wrote:




...

I have the raw footage on DVD.* Perhaps I can find a "free" video
editor program and pull out the car pulley sequence and upload to
google drive.* We'll see...



Dan




On 10/6/2015 9:21 AM, Dan Marotta
wrote:




Thanks, Bill.



I only did a couple of pulley tows for the filming of the ESPN
thing.* Some of the raw footage (not shown on TV) shows the rear
end of the car being lifted sufficiently that the driver lost
control of the car.* Fortunately the passenger/observer was
Emerson Fittipaldi and he reached across, took the wheel, and
straightened out the car.* When I released, it was quite a sight
seeing the rope literally slamming down on the runway.* I can
easily imagine the tangles this caused in the pulley system. =-O



Dan




On 10/5/2015 6:18 PM,
wrote:







Dan, a pulley tow launches a glider just fine - but then you need to reset for the next launch. Often, this means untangling the rope. Straight auto tow or winch launch rarely tangles the rope.

There are very few pulley tow operations in the world and cycle time is the usual reason why they gave up on pulleys and moved on to winch launch.


On Monday, October 5, 2015 at 9:16:28 AM UTC-6, Dan Marotta wrote:


I once flew for an ESPN video on flying (Secrets of Speed).* One of
the launch methods used was an auto pulley tow wherein the pulley
was mounted to the receiver on the back of the car and the cable was
staked to the ground near mid field.* The car drove in the takeoff
direction during the launch and, with the 2:1 advantage of the
pulley, it was every bit as exciting as a winch.* The car drove at
about 1/2 the speed of the glider.* We were using a 3,400' runway
and I don't recall the release height, though it was not as high as
a winch with a full runway length of cable.




On 10/5/2015 5:01 AM, GB wrote:



Good question. Seems to me reverse car tows(fixed pulley windward car drives toward the glider) would be the way to go. Has there been any sailplane work with car mounted pay out winches? Pay out winches are what the hangglider and paraglider community have mostly settled on using. Both of these solutions somewhat mitigate the space needed to auto tow.






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Dan, 5J






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Dan, 5J




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Dan, 5J




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Dan, 5J

Yep. That's why we had 400 pounds of bricks in the trunk of our autolaunch car.