John and others http://groups.yahoo.com/group/pulleylaunch/
It is interesting to learn of your experience. I must say I am a little suprised that your rope winch is designed to be able to handle knots. My understanding was that the spreader mechanism is normally vulnerable to knots passing through it ? I have seen a video of the SGCC winch and it is very impressive. Some of the features I liked about it included: -used rope -operated side on - mobile if the vehicle is licenced For smaller rope (ie 4 - 6 mm polyprop) towing hang gliders we used to wrap black insulation tape around the reef knots. If more tape was wrapped around each join every 3 or 4 days of flying then the knots would outlast the rest of the rope. If no tape was used, a wear point on each knot would quickly develop and the rope would soon break at the knot. The secret to the tape was that it did not fit completely flush on the knot and you would get a couple of mm wear protection when in fact your tape was much much thinner than 1 mm. I wonder if the tape concept would work with 8 or 10 mm rope getting dragged at higher pressures and speeds ? Have you or anyone else tried it? Cheers Michael On Thu, 9 Mar 2006 19:07:50 +1100 (AUS Eastern Daylight Time) "John O'Neill" <[EMAIL PROTECTED]> wrote: > > ---------------------------------------------------------------- > Michael, > > At SGGC we often tie a reef knot with the ends tied to keep things moving > when we are busy. > The knots on our 10mm polyprop rope are usually good for about 20 or 30 > launches compared to to 100plus splices. > We normally cut out the splices before the start of the next days operations > > > John > > -------Original Message------- > > From: Michael Derry > Date: 03/09/06 18:42:10 > To: Discussion of issues relating to Soaring in Australia. > Cc: [EMAIL PROTECTED] > Subject: Re[2]: [Aus-soaring] Re: [pulleylaunch] Knots? > > If > -it takes 30 seconds to tie a knot > -10 minutes to do a splice > -you need to carry a splicing tool > -you need someone who is trained and wants to do it > > Why would you bother to splice...unless you used a winch and were > therefore forced to do it ! > > KISS > > Keep It Simple Stupid !!!!!!!!!!!!!!!!!!!!!!!!!!! > > On Thu, 9 Mar 2006 16:38:44 +1300 > "Brett Kettle" <[EMAIL PROTECTED]> wrote: > > > Why not splice it? > > > > -----Original Message----- > > From: [EMAIL PROTECTED] > > [mailto:[EMAIL PROTECTED] On Behalf Of Michael > > Derry > > Sent: Friday, 10 March 2006 5:38 AM > > To: [EMAIL PROTECTED] > > Cc: aus-soaring; Winchdesign Yahoogroups > > Subject: [Aus-soaring] Re: [pulleylaunch] Knots? > > > > To: http://groups.yahoo.com/group/pulleylaunch/ > > cc others > > Neil > > > > I should have expanded a little more about knots. > > > > A FEATURE THAT OUR COUSINS USING WINCHES CANNOT TAKE ADVANTAGE OF > > > > The knots which we used that worked were reef knots. > > > > If you look at a reef knot, the knot sticks out one side and the two > > lengths of rope line up under pressure. So when you watch a rope with a > > reef knot in it go around a pulley at speed and under load the line of > > the rope goes right against the pulley and the reef knot sticks out to > > the side. > > > > After watching knots go around pulleys many times under load I was > > amazed to see that the line of the rope always went against the pulley > > and the knot was on the opposite side. > > > > Reef knots slip easily so we tied a knot at the end of each peice of > > rope to stop it slipping. This worked a treat. > > > > A knot savy pilot saw a reef knot we had tied before a launch and > > replaced it with some other superior knot in terms of strength. > > Unfortunately when the knot went through the pulley it snapped. The > > reason it snapped was that the two lengths of rope did not line up when > > under pressure and the knot did not stick out to the side. The knot was > > on the inside of one of the pieces of rope and acted as a fulcrum > > placing much stress on the rope at the edge of the knot. > > > > Has anyone eany other thoughts about knots.....it is a big subject ? > > > > Regards > > > > Michael Derry > > > > "Neil Wolthers" <[EMAIL PROTECTED]> wrote: > > > > http://groups.yahoo.com/group/pulleylaunch/ > > > > > Is there any particular reason you guys are using knots in the rope? > > _______________________________________________ _______________________________________________ Aus-soaring mailing list Aus-soaring@lists.internode.on.net To check or change subscription details, visit: http://lists.internode.on.net/mailman/listinfo/aus-soaring
