Closing Loop Tack

[MexPilot 0]

I plan on making some closing loops with Spectra 1000. I know a tack is not needed, but I do remember something about tacking with a straight stich as opposed to a bar-tack or zig-zag? I cant remember why and I cant find it in any of my manuals. Any info?

Thanx

"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return." Leonardo da Vinci

[riggerpaul 1]

Maybe you heard something from me.

I was taught to stitch fingertraps with a zig-zag, not a straight stitch or a bar-tack.

The theory is that a straight stitch should not be used where the stitching needs to stretch.

Bar-tacks have some straight stitching underneath the zig-zag, so they don't stretch well either.

[likestojump 3]

certain Pilot rigs specify a 301 straight stitch on the closing loop - that's about all that I *think* I heard. I believe the reasoning was that the zigzag does more damage to the canopy, as the loops are seated in the backpad.

[riggerpaul 1]

Interesting. I'm not very familiar with pilot rigs, so I certainly don't mean to argue.

But could you explain a bit more?

You say the straight stitch will damage the canopy less. Is this closing loop stitched to the canopy?

[likestojump 3]

Here's the quote from :
http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=3085909
"A straight stitch is used when the sewn area of the loop comes in contact with the canopy fabric on most containers. "

the closing loop passes between the folds of the round canopy as you lay it in the container - no freebag or sleeve is used, just like packing a round in a sport packtray.

[JerryBaumchen 1,450]

Hi likes,

  Quote

the reasoning was that the zigzag does more damage to the canopy

I recall something like in a Para-Gear catalog because ( I 'think' I remember ) that they straight stitch the loops that they supply.

Anyone else??????

JerryBaumchen

PS) In the past I have straight stitched them and, upon re-pack, have never found any thread broken. Although, if for a 1-pin then why stitch; just tie the knot at the bottom end as that sets the length.

[riggerpaul 1]

So, I'm learning something here.

When I was taught to use a zig-zag, I think we were talking about sewing loops on steering lines.

I never imagined that it would be different for a loop in a different place.

I know that I've taken apart a lot of zig-zag stitches from loops on lines attached to a canopy, but again, this isn't a closing loop on a pilot rig either. (Also, I am sure they were simple zig-zags and not bar-tacks that would have had straight stitching underneath the zig-zag.)

Thanks, all, for taking the time to explain.

[MexPilot 0]

Now that I am reading all this the straight stich does sound right. I believe it was regarded to pilot rigs. Although for some reason though my mind still thinks there is something else related to the straight stcich on a closing loop. Zig Zag is correct for fingertraps and line assembly example old school nylon thread where you had lines atached with a clove hitch and a half hitch. The Zig Zag allows for stretching. Thanx for the feed back.

"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return." Leonardo da Vinci

[deadwood 0]

The old wife’s tale I remember was that you should use a straight stitch on a closing loop that went through a free bag as a wide zigzag stitch would act like a “saw” and with repeated flexing of the container possible damage the canopy.

As to a straight stitch not stretching as much as a zigzag, that’s true. But a straight stitch made of nylon should stretch more that the spectra you are making the closing loop out of right?

He who hesitates shall inherit the earth.

Deadwood
Skydive New Mexico Motorcycle Club, Touring Division

[RiggerLee 61]

I'll toss out a theory. I've seen a lot of old loops made with a straight stitch. I'm trying to recall the containers that I've seen them in over the years. A lot of the loops That traditionaly seem to be built this way were long continueous double ended loops used in two pin pilot or sport rigs. In that case in the event of a partial pull, one pin cleared, where the continueous loop was ment to let the pilotchute launch regardless you would have a very long loop winding it's way through a lot of flaps and grommets. A stiff bartack or tight zigzag might create a stiff spot locking the container when it could not turn the corner around a grommet. A long straight stitch might be softer and more flexable and althoue it's under stress it's not being shock loaded so I doubt the lack of streatch is so big an issue. In fact althoue you make a good argument for zigzags over bar tacks I'll point out that most suspension lines are bartacked with staying stitches and that doesn't seem to be the bigest failure point.

Lee

Lee
lee@velocitysportswear.com
www.velocitysportswear.com