Kitebuilder.com

[Al Hargus]

[Stan]

Great post Al.

I've sliced myself on Spectra and Kevlar, and agree about thin diameters being the worst.
The paranoia about Kevlar (and to some degree manjha) gets pretty heated sometimes. It's just line, and will only cut another line if made to do so. BTW, I've seen cotton line cut Spectra, so maybe we should ban those evil cotton-heads!

[Al Hargus]

[Jones Airfoils]

Interesting tests Al. That's how Pete Ianuzzi would go about things! Good read.

I agree Kevlar has it's uses also, but I disagree with your assessment that Skybond was useless, since it was great inexpensive performance trainline material. Spectra is still inferior to Kevlar trainlines IMHO and for many reasons that your tests bear out, so no need to regurgitate the knowledge you've shared. Now I agree Skybond was rotten stuff as fly lines but the problems it presents as fly lines do not manifest themselves when used as train lines, and on the rare instances they did, it's arbitrary since trainlines don't twist around each other as fly lines do and their spans are short. Spectra just stretches too much right off the spool compared to Kevlar of equal strength so Spectra's accuracy is inferior to Kevlar, especially when mass producing trainlines on a jig and your stacks are expected to be locked-in out of the bag everytime. Plus, it had the benefit of being 'friendly' Kevlar. You can get Spectra to work fine but you'll need a slightly larger diameter to compensate for it's stretch inferiority to Kevlar, otherwise you'll need to spend some time flying your stack, dissassembling it, measuring the trainlines, adjusting...anyway...my $0.02...you can get pretty sick with obsessing over rigging accuracy...Edeiken would No-Knot all of his Kevlar trainlines...

Mike
_________________
Que Veneno!

www.jonesairfoils.com

[Al Hargus]

"Jones Airfoils" said. "Interesting tests Al. That's how Pete Ianuzzi would go about things! Good read."

MIKE - Good to hear from you. It's been a while!

I agree about the use of SkyBond as an effective train line for stacks. I guess that I did come down kinda hard on that line, but as "Flying Line" it wasn't a good idea. I have two stacks of Revs that are trained with Sky Bond so it does have it's uses!

The stretch problem with Spectra has cause a lot of problems for a lot of fliers when used as train lines! Two ideas I've used to "Prestretch" Spectra for any use (both I'm sure you already know Mike)

- Use old Spectra flying lines as train lines. Prestretched already!

- Latest "Al's slightly weird" stretching method = I take line down to work (print shop) and lay out the length I'm going to use. One end to an Eye bolt in far wall and other end secured to our 2ton Lift Truck. After I measure the line I "Back Up" the Lift Truck and put the line under tension. (Tricky! Not too much or I break the line, but TIGHT as a violin string)

I then go back to work for about an hour with line under tension. The line NEVER again stretches. I've used this "Prestretch" method with the new 125 foot Quad Line sets we have been using for Quad team here in the Midwest and after the "Prestretch" the lines NEVER change length again!

Again Good to hear from you Mike
_________________
GOOD WINDS

AL
Columbus, Ohio
USA

[KiteSquid]

Another way to prestreach line is to fly a kite on it!!!!


Be sure to pluck it like a guitar string to set up vibrations so the fibers can lay down....



Just do it on an open field.....
_________________
VR/
KiteSquid
AKA TakoIka
AKA Harold
King George VA


P.S. Yet another post by the Squid..... Doesent he ever shut up???

P.P.S. The wind is like the air, only pushier.

[Jones Airfoils]

I have a 20' jig that uses weights and large diameter smooth hooks. I'm sure there are a million ways to do it, but you didn't have to do any of that with Skybond. And Kevlar doesn't have the consistency issues Spectra does like Al mentioned, especially when it's associated with kites, again, as Al has already mentioned. Kevlar just comes off the spool ready to go much better.
_________________
Que Veneno!

www.jonesairfoils.com

[kiteman]

What a great write-up. I don't fly on Kevlar often, but I have taken to building my large 4-line foils with a Kevlar bridle. My foil speeds are easily 30% higher with the reduced drag. You just have to be careful how you knot what to what. If one line has the ability to slip in a knot at all, make sure it's not the kevlar.

[StringDriver]

Hey Al,

Thanks for solving more than one mystery with your tests !
Not only do I have more information about Kevlar and Spectra, I now know why some of the contestants in the Flying Pig Marathon here in Cincinnati were wearing prostheses and special running shoes!

[kiteguy]