Winching - Reverse Auto Tow

Frank Whiteley wrote [snip] " we pulled all of the
wire from the drum and found it to be collapsing inward under the strain
of
launching the Twin Astir and L-13 under more power than the winch had
been
designed for."

This happened to another club, and I am concerned it might to us too.
What did you do do to fix it - could the ATC-type drum be suitably
reinforced to prevent it, or did it need a new drum which would no doubt
be of heavier material or with added stiffeners inside?

Chris N.

"Chris Nicholas" wrote in message
...
Frank Whiteley wrote [snip] " we pulled all of the
wire from the drum and found it to be collapsing inward under the strain
of
launching the Twin Astir and L-13 under more power than the winch had
been
designed for."

This happened to another club, and I am concerned it might to us too.
What did you do do to fix it - could the ATC-type drum be suitably
reinforced to prevent it, or did it need a new drum which would no doubt
be of heavier material or with added stiffeners inside?

Chris N.

It was repaired with steel pipe of a suitable diameter and thickness by the
late Robyn Pierce-Boby and Larry Green(e?). Since Enstone GC is defunct, I
have no idea how to contact Larry. Someone like Ken Sparkes may be able to
help with contacting Larry. I don't have the specific details, but the pipe
was cut to a suitable length and split into two halves and clamshelled
around the existing drums. Once welded into place, it was turned true and
balanced. Seemed to do the trick though I originally thought it inelegant
and perhaps trickier than just making new drums.

Frank Whiteley

Has anyone had experience with a reverse pulley system on asphalt runways and using a rope, rather than piano wire or cable? I am considering the feasibility of 1/4" Dacron rope on an 8,000' runway in Hobbs, NM. My concern is that the rope will wear out too fast, being drug at launch speeds (45-55 mph) down the runway. We do straight auto tow now with steel wire, but there are power lines in the area, and we couldn't risk 4,000+ feet of conductive cable being in the air in case of a break, or even a decent crosswind.

Spectra rope makes more sense, but I would like to use Dacron to prove the concept without as much investment. If it works, Spectra would likely make more sense for performance and longevity.

Stephen Layton
Hobbs, NM

I have about 2,000 winch flights. Most damage to rope/cable is done after glider release when rope hits ground and being reeled in fast at the same time, not launch. Synthetic materials are great because they are light and impact themselves less on ground.

On Tuesday, July 19, 2016 at 2:11:46 AM UTC+12, Gen Shib wrote:
I have about 2,000 winch flights. Most damage to rope/cable is done after glider release when rope hits ground and being reeled in fast at the same time, not launch. Synthetic materials are great because they are light and impact themselves less on ground.

Yeah but on a regular winch launch the cable is off the ground along its entire length pretty quickly. There won't be anywhere near enough tension with a reverse pulley system to keep the cable between the pulley and the car off the ground, especially as the length of cable increases as the glider gets higher and the tension becomes less.

Interesting pics he

http://www.coloradosoaring.org/think...ey/default.htm

Suggest you consider a 2:1 pulley launch. Gets the rope up off the concrete during the launch very quickly.

We've done 10 or so at Sunflower. 4000 feet of rope on a 7000 ft runway. Easy 1500 ft launches in our nose hook equipped 2-33.

Only time the rope drags on the runway is when (very slowly) resetting the rope after the launch.

On Monday, July 18, 2016 at 1:06:39 PM UTC-6, Tony wrote:
Suggest you consider a 2:1 pulley launch. Gets the rope up off the concrete during the launch very quickly.

We've done 10 or so at Sunflower. 4000 feet of rope on a 7000 ft runway. Easy 1500 ft launches in our nose hook equipped 2-33.

Only time the rope drags on the runway is when (very slowly) resetting the rope after the launch.

I'm not sure I see much advantage of a 2:1 system (assuming you mean the reverse-driving vehicle has a pulley as well). Wouldn't you still be dragging 4,000 ft of rope behind the tow vehicle (from the fixed pulley)? It hardly seems worth the extra rigging trouble...but I've never done it either. My primary concern is rope wear, and I'm not seeing much improvement with that. Please let me know what I am missing.

Stephen

During the 1960's and early 1970's the Dansville (NY) Soaring Club primarily used the car-pulley system as described above by Steve. The anchor was in the grass adjacent to the runway and midfield. The cars drove on the runway to avoid tearing up the grass. The system worked very well at a cost of $1 per tow and tow rope wear was reasonable, although rope breaks were quite common. Having a Chrysler dealer as a club member who provided old and large V8 junk cars, with excellent cooling systems, was essential to the fiscal viability of the car-pully operation. About 9" high runway lights were installed in the early 1970's which required addition of thin tube tripods that covered each light to allow the rope to slip over the light rather than tearing up the light. Later the runway lights were replaced with ones that are about 2ft high which made car-pulley launches not viable.

On Sunday, November 2, 2003 at 1:49:20 PM UTC-5, wrote:
Can anyone direct me to Clubs / Web sites using this method of launching -
Interested in finding out more about this method, particularly from clubs
that operate from gravel/dirt strips

Thank you


John Spargo

Bruce: I can give you some quantitative numbers. In 1966-67 I made ~70 car-pulley tows in a 1:26 at Dansville using an asphalt runway that is almost 4000ft in length. The average tow was to 1300ft with some tows to 1500ft when the wind was optimum. For comparison, in 2009 I gave many instruction winch flights in either a Blanik L13 or a ASK21 using the same runway at Dansville. The average tow again was 1300ft and 1500ft when the wind was favourable. Thus under similar circumstances car pulley and winch give essentially the same height. Winch tows can utilize the full length of the airfield whereas car pulley tows are limited to the length of the paved surface because of the damage caused driving on the grass. Also winch tows are less intrusive than car pulley if the airport has mixed power and glider activity.

Doug C

Does anyone have particularly bad experiences with pulleys used like this. I am talking about the pulleys themselves. Has someone found a particular diameter that is too small. Obviously larger is better for both bearing speed and rope bending, but there are limitations on cost and availability....particular for the trial run I'm thinking about. I am considering a trial run with a swiveling pulley on the receiver hitch of a pickup, no guides, just the pulley, with around 8,000' of 1/4" poly hollow braid, flying a 1-26. That should prove the launch height, assuming the rope doesn't break on the first launch. I'm not sure what to expect at the pulley end, and don't want the rope jumping out of the sheave, catching and breaking. I doubt it will, but have no experience to back it up.