From: ar12@quads.uchicago.edu (Andre Robotewskyj) Subject: About reinforcing sail seams? Message-ID: <1993Feb5.163944.6250@midway.uchicago.edu> Organization: University of Chicago Date: Fri, 5 Feb 93 11:39:44 EST Hi ho, Well, I'm about to start construction of my monster stunter- I've finalized the design to a 16.5' scaled up version of the NS Extreme- Having experienced the effects of sail stretch, I was wondering if it might not be a bad idea to reinforce panel seams with lengths of 3/4" dacron tape (folded in half to 3/8" width) which could be sewn into the seams- this would seem to minimize sail stretch as presumably much of the sail tension would be distributed along the low stretch dac ron seams- does anyone have an oppinion concerning possible cons in such a design? Andre = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = From: sasaki@netop3.harvard.edu (Marty Sasaki) Subject: Re: About reinforcing sail seams? Message-ID: <1993Feb9.200106.19693@das.harvard.edu> Organization: Harvard University Date: Tue, 9 Feb 93 15:01:06 EST In article <1993Feb5.163944.6250@midway.uchicago.edu>, ar12@quads.uchicago.edu (Andre Robotewskyj) writes: >Well, I'm about to start construction of my monster stunter- I've >finalized the design to a 16.5' scaled up version of the NS Extreme- >Having experienced the effects of sail stretch, I was wondering if >it might not be a bad idea to reinforce panel seams with lengths >of 3/4" dacron tape (folded in half to 3/8" width) which could be >sewn into the seams- this would seem to minimize sail stretch as >presumably much of the sail tension would be distributed along the >low stretch dac ron seams- does anyone have an oppinion concerning >possible cons in such a design? This is an area of great interest to me. Several kites currently on the market have trailing edge reinforcements to try and take control of the stretch. Many manufacturers carefully lay out panels on their kites so that the stretching of the fabric will aid the desired flight characteristics of a kite. Ask Bob Childs about the Jabberwocky, or ask me about the Katana. The characteristics of the fabric also have an effect on stretch. As an example Carrington stretches much more, both along the grain and the bias, than U.S. domestic fabric. The new Icarex fabric, and other polyester fabrics have much lower stretch along the grain and about the same as domestic fabric on the bias. Adding reinforcing tape won't stop the kite from stretching, it will just cause it to stretch in different ways. I would suggest sticking to conventional construction techniques, and learn to live with the stretch. That's why bungee cords are used on so many kites, they help compensate for sail size variations. Use dacron tape for certain high stress seams (like along the spine). -- Marty Sasaki Harvard University Sasaki Kite Fabrications sasaki@noc.harvard.edu Network Operations Division 26 Green Street 10 Ware Street Jamaica Plain, MA 02130 Cambridge, MA 02138-4002 phone/fax: 617-522-8546 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = From: northg@egr.msu.edu (George M North) Subject: Re: About reinforcing sail seams? Message-ID: <1l98c2$fsj@msuinfo.cl.msu.edu> Date: Tue, 9 Feb 93 16:40:18 EST Organization: Michigan State University I wouldn't think that it would be a wise idea to use dacron in the seems. You want a sail to take on a smooth shape and seems need to strech with the fabric to give it the correct shape. I would recommend that you just be careful to lay out your fabric with your grain going the right way and then you could use dacron along the trailing edge or better yet ues some line and run it along the trailing edge to keep it tight. you wan't to keep that part of the kite as taught as possible. Good luck George. = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = From: salanne@convex.csc.FI (Simo Salanne) Subject: Re: About reinforcing sail seams? Message-ID: <1993Feb10.085724.22441@nic.funet.fi> Organisation: STACK Finland Organization: Finnish Academic and Research Network Project - FUNET Date: Wed, 10 Feb 93 03:57:24 EST In <1993Feb9.200106.19693@das.harvard.edu> sasaki@netop3.harvard.edu (Marty Sasaki) writes: >an example Carrington stretches much more, both along the grain and >the bias, than U.S. domestic fabric. The new Icarex fabric, and other >polyester fabrics have much lower stretch along the grain and about >the same as domestic fabric on the bias. Does anybody have hands on experience on Icarex? I got few meters of samples, but have not done anything with them yet. Smooth Winds Simo Salanne = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = From: sasaki@netop3.harvard.edu (Marty Sasaki) Subject: Re: About reinforcing sail seams? Message-ID: <1993Feb10.164041.8563@das.harvard.edu> Organization: Harvard University Date: Wed, 10 Feb 93 11:40:41 EST In article <1993Feb10.085724.22441@nic.funet.fi>, salanne@convex.csc.FI (Simo Salanne) writes: >>an example Carrington stretches much more, both along the grain and >>the bias, than U.S. domestic fabric. The new Icarex fabric, and other >>polyester fabrics have much lower stretch along the grain and about >>the same as domestic fabric on the bias. > >Does anybody have hands on experience on Icarex? I got few meters >of samples, but have not done anything with them yet. I have no experience with Icarex, but I have made several kites using polyester fabric from Japan. The major advantages are the lack of stretch, and the greater strength. Most kite designs aren't affected much by the lack of stretch, but some of the highly stressed taut sail designs require a bit of tinkering. A polyester Katana is a little bit wider before putting the sticks in. This was done to give a slightly deeper sail with the sticks in. This adds a bit of stability to the kite. The bridles can be set a bit higher for a similar amount of oversteer. The higher bridles also give the kite a little more speed, bringing it up to the same speed as a Carrington Katana. Polyester is also a lot more colorfast. Last year's team kites had one blue polyester panel which has no noticable fading while the other three panels have obvious fading. -- Marty Sasaki Harvard University Sasaki Kite Fabrications sasaki@noc.harvard.edu Network Operations Division 26 Green Street 10 Ware Street Jamaica Plain, MA 02130 Cambridge, MA 02138-4002 phone/fax: 617-522-8546 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =