Stretching spectra lines

[jheadley 0]

I was once shown a trick where you take an out of trim canopy with spectra lines and slightly put it back into better trim by anchoring down all the lines and then giving a few quick tugs on the lines you want longer (typically the outside ones). This seems to tighten the weave and increase the length of the line by an inch or two. I've tried it and as far as I can tell it actually does seem to work, at least at first. I don't know if it shrinks back after a few deployments or if there are any negative effects of doing that. Does anyone have any comments about this?

[phoenixlpr 0]

I have seen this magic by Brian Germain. The owner of the canopy told that his canopy opened lot better after that.

[jheadley 0]

The thing that makes me and others skeptical about it actually working long term is that it just seems too easy. You don't even have to pull very hard for them to stretch. If they stretch that easily, wouldn't they stretch on every opening?

[henrik.anderson 0]

Quote

The thing that makes me and others skeptical about it actually working long term is that it just seems too easy. You don't even have to pull very hard for them to stretch. If they stretch that easily, wouldn't they stretch on every opening?

The one that stretch will, and the other like outerlines with less stress on them, and more friction from slider will shrink.
This is easy if you have the linespec. I have done this several times on mostly older Sabres.

[jheadley 0]

I was playing with some lines yesterday and here's the short version of what I found.

I had a canopy with LST's that were 1.25 inches off ( I found lots of twists in one steering line, only a few in the other, so the twisted line shrank faster I'm guessing). I was able to stretch the shorter line so it was even with the longer one, but it shrank back a little after only a few minutes. I left it overnight and this morning measured it and there is a .5 inch difference between the right and left lines. So it appears that initially it did seem to stretch 1.25 inches, but it shrank back and eventually settled at .75 inches longer than it was originally.

Still no idea if it'll stay like this after being jumped though but I'll keep measuring it.

[morten 0]

Nice forum, this!Yesterday I searched for a thread on this subject, but didn't find it. Today I decided to start a thread and Bingo!

I jump a Sabre2-170 (1.35 lb/sqft) with 300 jumps in it. PD's linetrim-chart says that the A-lines should be the same length within 1/8" (correct me if I'm wrong about this!)

The outmost A-lines approx. 3" shorter than the center ones. As I get closer to the middle the lines get longer and longer with the 4 middle ones almost the same length. I've not checked the rest of the lines, but expect them to be similarly affected.

The openings are always soft , but recently I've had more off-heading openings than I used to - which means a lot of off-heading openings - including two rather hairy spinning linetwists in late summer, but no cutaways so far .

The Question: Is this canopy badly out of trim?

ps.: Additional comments on Brian Germain's magic line-lengthening trick would be nice - I'm probably going to try it out soon

[henrik.anderson 0]

It's definitly out of trim if it's 3".

Reset the trim: (1 hour work)
Fix the lines to something rigid I used a big bolt in a pillar.
measure a referenspoint I usually use center A-line.
measure that line A and recalculate te rest of the trim in the chart. If A-line is like 1" off the spec, then the rest of the lines should be off with the same.
Now start pulling the lines and measure them one by one.
And get them into spec.
If the c and d lines are much shorter then a and b lines it might be dangerous, it is closer to a stall.

Regards
/Henrik

[monkycndo 0]

I've watched Brian do it on several canopies during a canopy control class. The owners later reported it made an improvement.

50 donations so far. Give it a try.

You know you want to spank it
Jump an Infinity

[darkwing 4]

Quote

...The Question: Is this canopy badly out of trim?

Not badly, but it is out. Anything with spectra lines and more than about 20 jumps is probably out of trim in the sense that it won't meet factory new specs for line tolerances. In most cases it isn't anything to get worked up over.

-- Jeff
My Skydiving History