The rope on a payout winch is on a drum not simply attached to the rear of a truck. Straight auto-tow uses a release. A payout winch needs a guillotine.

On Saturday, May 18, 2013 10:03:48 AM UTC-6, Dan Marotta wrote:
Guillotine? How about simply mounting a release mechanism to the back of

the tow vehicle with the release cable within reach of the driver or

observer? That's the way they do it on the dry lake in Nevada and I was not

the least concerned about accepting ground launches. And, of course,

there's always the weak link at the glider end...





"Martin Gregorie" wrote in message

...

On Fri, 10 May 2013 06:19:27 -0700, son_of_flubber wrote:



Okay. I do have a few observations/opinions:



1)That the payout winch payouts more line and keeps line tension

constant when the glider hits lift seems an inherent advantage of this

approach when compared to a traditional winch launch.



As Bill says, a payout winch can't easily compensate for sink or a rear

gust at the start of a launch in calm conditions.



2)Don's suggestion that traditional winch launching is proven and that

there is therefore no reason to experiment with payout winching misses

the point. In a country where beefy pickup trucks are common, the

start-up costs for payout winching are much lower than traditional

winching. Secondly, far fewer humans need to be deployed and

coordinated to run a payout winch. The relevant question is "Which is

better to use on a dry lake bed, 1)autotow with payout winch or

2)traditional autotow? What are the tradeoffs?



As Don mentioned, we've been shown videos of payout winches with *no

gillotine fitted*. Its relatively rare, but cases of failures to release

have happened and are highly liable to be fatal without prompt use of the

guillotine. Even with a guillotine, what are the chances of a solo payout

winch driver noticing the problem in time? Even if he does notice, how

fast can he get to the guillotine's release and operate it?



I wouldn't accept a winch or auto-tow launch if there wasn't a functional

guillotine installed so that its release was instantly accessible to the

driver and/or the person monitoring the launch.





--

martin@ | Martin Gregorie

gregorie. | Essex, UK

org |