Almost perfect payout winch launch.

On Monday, May 20, 2013 10:02:54 AM UTC-6, wrote:
On Monday, May 20, 2013 11:00:54 AM UTC-4, Tony wrote:

On Monday, May 20, 2013 9:52:58 AM UTC-5, WB wrote:



In article , Tony wrote: If you're using a pulley why not just have a release on the tow vehicle? Hi Tony, I was unclear about the pulley launch. The pulley is on the tow vehicle. One end of the line is anchored, the line goes over the pulley to the glider. The tow vehicle is pulling from the middle of the rope, going in the same direction as the glider. The advantages are that acceleration at the glider is almost as fast as a winch launch and the tow car only has to go 25-30 mph maximum to launch the glider. No gear changes required, and the low vehicle speed means it can be done on less than paved surfaces. Launching with 4000 feet of dacron rope and an old LTD with 500 lbs of bricks in the trunk used to get our Ka-8 to 2000' if we had a bit of headwind. A release can be put at the anchor point, but that's a long way from where the action is. There are some other disadvantages to this type of ground launch as well. Turn around time is fairly long.. Switching ends of the rope after each launch can speed things up especially if the anchor point is another vehicle. Rope recovery can be problematic since a chute is usually not part of the rope end hardware, so the rope tends to fall a ways downwind.







ah i see, i was thinking of a fixed pulley.



Yes, fixed pulley has some advantages: quick turnaround, can use a chute, driver

is facing the action. The disadvantage is that you drag the whole rope the

length of the field at speed. I would think that would wear out Spectra

pretty fast. There's some places that use multiple pulleys that can

mitigate some of that. Check out the pulleylaunch Yahoo group for that.



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.

On Monday, May 20, 2013 8:26:41 AM UTC-6, Tony wrote:
On Monday, May 20, 2013 9:19:03 AM UTC-5, WB wrote:

In article , Martin Gregorie wrote: 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. We used to do a lot of ground launching via the "pulley method". We always had an observer in the tow car watching the launch. Our "guillotine" was a sharp machete in the hands of the observer. Of course we were also taught to immediately bank into a tight turn and circle the tow vehicle if we could not release. I always had my doubts about recognizing the release failure in time to cut the line or to turn and get tension off the line before things got out of hand. All the pulley launch rigs I have seen are just a bare pulley, usually a truck rim mounted an a trailer hitch. No fairleads or other structure. I guess a guillotine could be mounted to such a rig. Would be a good Idea, I think.



If you're using a pulley why not just have a release on the tow vehicle?

http://framework.latimes.com/2013/05...hed-sailplane/

On Tuesday, May 21, 2013 5:20:21 PM UTC-6, Frank Whiteley wrote:

http://framework.latimes.com/2013/05...hed-sailplane/

Bad Photoshop job. You can see the real rope going past the horse to something out of the frame that's really launching the glider. However, it would have to be a gentile something - that's a Baby Albatross with a, IIRC, 65mph Vne.

Bill D wrote:
On Tuesday, May 21, 2013 5:20:21 PM UTC-6, Frank Whiteley wrote:

http://framework.latimes.com/2013/05...hed-sailplane/

Bad Photoshop job. You can see the real rope going past the horse to something out of the frame that's really launching the glider. However, it would have to be a gentile something - that's a Baby Albatross with a, IIRC, 65mph Vne.

http://www.youtube.com/watch?v=86rOfjhsIIM