Winching - Reverse Auto Tow

On Tuesday, 26 July 2016 02:12:58 UTC+1, wrote:
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.

Hi, I wrote an article "The Expedition Pilot's guide to launching" in the Dec2013/Jan 2014 edition of the UK Sailplane and Gliding magazine. It may be of interest. I use 12mm diameter high density polypropylene rope (Skyrope from Skylaunch) on snatch blocks with, initally steel pulleys on plain bearings 110mm dia. The bearings cooked in spite of lots of grease! These have been modified for regular use to nylon pulleys with steel ball bearings. The steel flaps or cheeks of the snatch blocks keep the rope where it should be. I use either a 2 to 1 or 3 to one system to keep the tow speed down ( we use some rough fields). If you are serious then I can send you a copy of the article and details of the kit, as well as the links to YouTube videos of some launches in the Lake District (UK) using 2 to 1 pulley system, with one pulley on a ground anchor and the other on the car's tow hitch (with the rope tail to another ground anchor). Everything used is inexpensive, and it works. Pete Whitehead

On Tuesday, July 26, 2016 at 1:51:14 AM UTC-6, Peter Whitehead wrote:
On Tuesday, 26 July 2016 02:12:58 UTC+1, wrote:
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.

Hi, I wrote an article "The Expedition Pilot's guide to launching" in the Dec2013/Jan 2014 edition of the UK Sailplane and Gliding magazine. It may be of interest. I use 12mm diameter high density polypropylene rope (Skyrope from Skylaunch) on snatch blocks with, initally steel pulleys on plain bearings 110mm dia. The bearings cooked in spite of lots of grease! These have been modified for regular use to nylon pulleys with steel ball bearings. The steel flaps or cheeks of the snatch blocks keep the rope where it should be. I use either a 2 to 1 or 3 to one system to keep the tow speed down ( we use some rough fields). If you are serious then I can send you a copy of the article and details of the kit, as well as the links to YouTube videos of some launches in the Lake District (UK) using 2 to 1 pulley system, with one pulley on a ground anchor and the other on the car's tow hitch (with the rope tail to another ground anchor). Everything used is inexpensive, and it works. Pete Whitehead

Pete, I watched your videos, and those look like strong launches! Much better acceleration than we typically see. If you could send me an electronic copy of your article, I would love to read it.

On Wednesday, July 27, 2016 at 3:28:38 AM UTC+12, wrote:
On Tuesday, July 26, 2016 at 1:51:14 AM UTC-6, Peter Whitehead wrote:
On Tuesday, 26 July 2016 02:12:58 UTC+1, wrote:
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.

Hi, I wrote an article "The Expedition Pilot's guide to launching" in the Dec2013/Jan 2014 edition of the UK Sailplane and Gliding magazine. It may be of interest. I use 12mm diameter high density polypropylene rope (Skyrope from Skylaunch) on snatch blocks with, initally steel pulleys on plain bearings 110mm dia. The bearings cooked in spite of lots of grease! These have been modified for regular use to nylon pulleys with steel ball bearings.. The steel flaps or cheeks of the snatch blocks keep the rope where it should be. I use either a 2 to 1 or 3 to one system to keep the tow speed down ( we use some rough fields). If you are serious then I can send you a copy of the article and details of the kit, as well as the links to YouTube videos of some launches in the Lake District (UK) using 2 to 1 pulley system, with one pulley on a ground anchor and the other on the car's tow hitch (with the rope tail to another ground anchor). Everything used is inexpensive, and it works. Pete Whitehead

Pete, I watched your videos, and those look like strong launches! Much better acceleration than we typically see. If you could send me an electronic copy of your article, I would love to read it.

Yes, the launches shown here look like normal launches from a pretty powerful winch, not the average rather anaemic direct-pull car launch. Sadly, we don't see anything of the vehicle or launch setup

https://www.youtube.com/channel/UC_G...WaGdMMduefDVAg

On 7/26/2016 9:28 AM, wrote:
Snip If you could send me an electronic copy of your article, I would love to read it.

Or post it on Dropbox or similar so we can all read it!
--
Dan, 5J

I would get a 15 to 17 inch rim from a junk yard. Cheap, steel, plain. Then, get a stub axle and hub from Tractor Supply or the like with at least a 2000 lb load rating. No need for guides. No need for swivels. Axis of rotation for the wheel to be horizontal, running side to side. Your pull off angles to the side (for the anchor, or the glider while climbing) will never be more than a few degrees, and the rope will not want to climb out of the deepest part of the wheel. Don't add more complication than is needed. With 8000 feet of ramp, you probably don't need much more than 6000 feet of rope.

If you are anchoring the pulley (say, to a parked car), still no need for a swivel. Keep your life simple!

Just my two cents worth.

Steve Leonard

On Tuesday, July 26, 2016 at 8:38:31 AM UTC-6, Steve Leonard wrote:
I would get a 15 to 17 inch rim from a junk yard. Cheap, steel, plain. Then, get a stub axle and hub from Tractor Supply or the like with at least a 2000 lb load rating. No need for guides. No need for swivels. Axis of rotation for the wheel to be horizontal, running side to side. Your pull off angles to the side (for the anchor, or the glider while climbing) will never be more than a few degrees, and the rope will not want to climb out of the deepest part of the wheel. Don't add more complication than is needed. With 8000 feet of ramp, you probably don't need much more than 6000 feet of rope.

If you are anchoring the pulley (say, to a parked car), still no need for a swivel. Keep your life simple!

Just my two cents worth.

Steve Leonard

Steve, that is exactly what I was planning to do at first. As I looked at other applications, I began to think that I was making it too simple, and needed more precision. Maybe some other designs are overly complex.

We've been using an auto-mounted pulley launch system for over 50 years, and the idea came from the Dansville, NY club who've been using it since the Wright Bros.

Initially, launching a K-8, a 1965 V-6 Jeep was enough. A 300 ci Olds V-8 engine was installed when glass ships with ballast came along. Later, something with more muscle was needed to launch a ballasted Duo Discus so the vehicle used now is a supercharged 454 ci Chevy Suburban.

Traction has been a problem from day one, especially on early morning launches on wet grass. The jeep was equipped with chains on all four wheels which was still marginal during the soft ground in spring. To harness the 600 hp of the '99 Suburban a 350 foot paved strip was added, and this "launch pad" does the trick. Catapults to 150 feet altitude (all we need on the ridge top) take seven seconds for a 15M ship and 10 seconds for the Duo.

With the 2 to 1 reduction in required vehicle speed due to the pulley on the Suburban there is no need for the transmission to shift gears, so we use first gear, high range, 4wd. The glider releases from tow just as the Suburban reaches the end of the pavement. The throttle is floored until the glider calls "3,2,1,release" at which point the throttle is cut back.

Tow cable used is 3/16th galvanized. It lives outdoors. The pulley is a MG B trailing arm suspension welded to a 2 in coupling ball with the 13" steel wheel serving as the pulley. Totally indestructible, it has giving flawless service for 52 years.

Karl Striedieck

Karl-

Apparently, you have figured out the solution for your operation. I can only offer one suggestion:

Bluetooth.

According to Dr. Sheldon Cooper on the "Big Bang Theory." everything is better with Bluetooth.