seeking data on hma-line shrinkage

[feuergnom 29]

that's a question for all the riggers in here:

i jump a nitro (nitron in the u.s. market) equiped with hma/technora lines. i chopped it this weekend and went to my riggers to check for line-trim (some of the last openings were a little bit odd thus the check for trim) - what we found was that all the lines had got shorter for approx. 3 cm, the steering lines had lost more than 5 cm.

canopy has 195 jumps and is 2 years old.

so basically i am looking for info on how much and how quickly do hma/technora lines shrink and if you have any comparison on how the shrinkage affects flying & opening characteristics

edit: thanks for your input, if you don't want to post you can pm me

The universal aptitude for ineptitude makes any human accomplishment an incredible miracle

dudeist skydiver # 666

[ianmdrennan 2]

WOW, I'd love to hear what they say too. I was under the impression that HMA was the type LEAST likely to change trim over time.

Hopefully Beezy will answer.

Blues,
Ian

Performance Designs Factory Team

[billvon 3,111]

>all the lines had got shorter for approx. 3 cm . . .

All the lines? That would be extremely unusual for Spectra; traditionally the outer lines shrink significantly and the inner ones shrink much less (due to different amounts of wear.) It would be interesting if there was a different mechanism at work here.

[masterrigger1 2]

Technora ( one type of HMA) does not shrink.
The Technora that is on your canopy probably came from Germany.
I do not think there is any difference from the line that comes from Germany verus the line that we have CSR(line manufacturer) braid for us.

We have been experimenting with this fiber for almost three years and have yet to have any shrink.

It does elongate over time, but not alot. Maybe 1/2 inch after about 450 jumps.

It makes me wonder if the line trim specs you used were the manufacturing specs. They will vary greatly between the finished specs.

MEL
Skyworks Parachute Service

Skyworks Parachute Service, LLC
www.Skyworksparachuteservice.com

[beezyshaw 0]

The line specs you have include measuring the connector link; why Klaus included the link in these trim specs is unclear, but from what you say the canopy is in perfect trim. As has been pointed out before, the Technora lines on your Nitro will not shrink like spectra does. Your lineset is made from the most dimensionally stable fiber ever used in parachute lines. If you have any more questions about your Nitro or its lines please feel free to contact me by PM or email.

[feuergnom 29]

Quote

if the line trim specs you used were the manufacturing specs

we used the specs the rigger got from the manufacturer (hiper performance) - so i can't to more than stick to these

it puzzles me quite a bit if you state "They will vary greatly between the finished specs." - could you elaborate on this? i'm really curious...

The universal aptitude for ineptitude makes any human accomplishment an incredible miracle

dudeist skydiver # 666

[feuergnom 29]

i had no idea that the lenght of the connector links has to be included when measuring for trim...

pm is on the way

The universal aptitude for ineptitude makes any human accomplishment an incredible miracle

dudeist skydiver # 666

[masterrigger1 2]

Quote

Quote

if the line trim specs you used were the manufacturing specs

we used the specs the rigger got from the manufacturer (hiper performance) - so i can't to more than stick to these


it puzzles me quite a bit if you state "They will vary greatly between the finished specs." - could you elaborate on this? i'm really curious...***

Depending as to which manufacturer, the way the lines are layed out, tensioned with weight,marked and cut.

Some use weight some do not.

Also the fingertraps at the upper loops, lower loops, and cascades make the overall length of the lines shorter than when marked on the line table.

Bartacks also have some takeup.

BS,
MEL

Skyworks Parachute Service, LLC
www.Skyworksparachuteservice.com

[riggerrob 643]

Hee!
Hee!
Welcome to the dark art of reading canopy trim charts.
Every canopy manufacturer insists on inventing their own method for measuring lines and it takes years for riggers to learn the secrets.
For example, Performance Designs measures all the (Maillon Rapide) connector links and brake eyes anchored to the same hook. PD quotes a "base line" length for A lines, then compares the other lines ot that base line.
Oh! Wait a minute, PD stopped shipping new canopies with Maillon Rapide links a couple of years ago.
Hee!
Hee!
Meanwhile, Strong Enterprises only measures lines when they attached to risers.
Just to mess with you, Para-Flite measures steering line length relative to D lines.
Reading trim charts is truly a dark art.

Sinister laughter!!!