Vectran vs. Spectra lines

[Geoff 0]

OK - It now seems widely accepted that Vectran lines stay in trim better than Spectra, but that Vectran is more susceptible to wear and sudden failure.
The problem area seems to be the lower control lines, which get the most wear, and because they're not loaded during deployment, are more likely to fail during the flare or swoop. Crunch.
So - I'd be interested in opinions on the following:
(1) Do the thicker (1000lb?) vectran lines which Icarus now install as brake lines really improve things?
(2) Why not use Spectra just for the lower control line section? This shouldn't affect the trim very much. (not my idea - I read it on rec.skydiving)
(3) Is the improvement in trim from Vectran significant, even for very high performance canopies, or are we just becoming victims of the latest fashion?
Thanks for any opinions.
Geoff

[alan 1]

So - I'd be interested in opinions on the following:
(1) Do the thicker (1000lb?) vectran lines which Icarus now install as brake lines really improve things?
Yes, but the real question is how much do they improve things. I am not sure.
(2) Why not use Spectra just for the lower control line section? This shouldn't affect the trim very much. (not my idea - I read it on rec.skydiving)
Probably my post. I have replaced my lower brake lines with Spectra after discussing it with an Icarus rep. I am happy with the results. She said we may see this from the factory sometime soon. I guess time will tell.
(3) Is the improvement in trim from Vectran significant, even for very high performance canopies, or are we just becoming victims of the latest fashion?
Spectra appears to be superior to Vectran in all but one category, it does not retain its' original length as well. Line trim is indeed critical to some of todays high performance canopies, but in varying degrees, not all. My opinion is that Spectra would be the better(safer) choice if jumpers could be relied on to replace lines at the recommended intervals. Unfortunately, we can't. We tend to replace them when they 'look' really bad or the canopy starts to fly and perform extremely poorly. This would generally be too late on some of todays extremely high performance canopies. With Vectran, they look like crap after 200 - 300 jumps, and so we replace them.
alan

[alan 1]

I just thought I'd add this here as well. I received via e-mail in response to a post I made in rec.skydiving on this question. Here is the cut and paste:
Alan,
I saw your rather detailed post on the merits of
Spectra and Vectran. Interestingly enough, it turns
out that sail makers use mono-filament fibers, like
Spectra and Vectran, to carry the loads in sails.
Below is a breakdown of properties for Spectra and
Vectran, taken from the July/August 1997 issue of
"Sailing World" magazine. Take note that these
properties are for a given denier, and will not
correlate exactly to a combination of fibers, such as
a braid used in a suspension line. The results are
interesting though, and generally reinforce what
skydivers already know or are finding out. What jumps
out at me are the values for "flex life" and "UV
resistance". There appears to be a substantial
difference in the two fibers in these areas, but I
have yet to hear this mentioned in the context of
skydiving.
*******************Begin Quote*******************
SPECTRA
Initial modulus = 1250
Tenacity = 33.5
Flex life = not affected
UV resistance = 6 to 7 months
Elongation to break = 5%
VECTRAN
Initial modulus = 510
Tenacity = 23.0
Flex life = 15%
UV resistance = 1 to 2 months
Elongation to break = 2%
Where ... "Initial modulus" is a measure of the
fiber's ability to resist stretch. The higher the
number, the less the stretch. "Tenacity" is a measure
of initial breaking strength. The higher the number,
the more load it takes to break the fiber. "Flex
life" is a measure of the fibers ability to retain its
strength after being folded back and forth. It is
expressed as a percentage of the fabrics strength lost
after 60 bend cycles. "UV resistance" is the amount
of time it takes for the fiber to lose 50% of its
initial modulus. "Elongation to break" is a measure
of the fibers ability to resist shock loads. It is a
measure of how much a fiber will stretch before it
breaks.
Spectra has a weird characteristic when it is highly
stressed - it "creeps" - which is essentially
permanent stretch. Spectra has superb durability; it
doesn't mind flex, sunlight, or chafe.
Vectran ... suffers more in sunlight. Unlike Spectra
it does not creep, but it's also very expensive.
*******************End Quote*******************
blues,
Andy
I would like to make a note here that while this article refers to Spectra "creep" as a permanent stretch, what happens in the parachute suspension line application is that it reacts to the heat generated by the slider and deployment forces by permanently shrinking.
alan

[phorty 0]

Hi Guys, I just ordered a Safire from Icarus and was asking the same question. If you go to their website you will notice that they have a warning re:Vectran in red now. They are now recommending you go with the Spectra line set for the Safire as it can go out of trim w/o affecting performance as much as other ellipticals. Blue ones!

[ramon 0]

You may know this but here is what Brian Germain (of Jedei fame) does with is new Samurai canopies.
Our lines are Spectra, with the exception of the out-board line and brake lines, which are made from Vectran. This proven method extends the usable life of the lineset significantly above customary methods.

[DistantThunder 0]

Sorry to swim in somebody else's pool-
I'm not a rigger, but I do work in commercial sewing-specifically custom tactical gear. There has lately been a huge debate in some areas of the tactical arena over Spectra body armor having failures when exposed to heat such as being left in the trunk of a car or a wearer spilling hot coffee on him/herself. In addition, there was some concern about Spectra failing after exposure to moisture, etc. There is more information available over at Tacticalforums.com under the Mad Dog Labs heading.

[rmsmith 1]

I've been wondering about the smaller Vectran and HMA lines being subjected to gamma radiation at the airports these days. Sunlight is relatively low energy with a long wave-length, which only affects the exterior fibers first. However, gamma radiation is extremely powerful with a very short wave-length, which easily penetrates all of the fibers throughout the line. I also understand that most of the parcel services now scan their customer's packages with such devices. The only realistic option is to replace these lines on a shorter interval as the penalty of line failure is just too great.

[drbartling 0]

X-Ray (at the airport or normal shipping) or Gamma scanners (for large freight international shipping(not likely your gear will ever see this)) have no impact on your line wear. Tin foil hats, however may rub against the line causing abrasive damage.

[hackish 8]

I have a rig here that I built some years ago to test out some strengths of closing loops. It would be interesting to put some spectra through some of the hot coffee/wet tests to see if it's affected. I don't have a good source of gamma radiation though...

-Michael

[jumpwally 0]

OUTSTANDING !!!!

smile, be nice, enjoy life
FB # - 1083

[Mentosfresh 0]

Interesting, I read that Spectra is not supposed to absorb moisture at all.

A new fiber to keep an eye on is the new Dyneema DM20. It is basically Spectra, but this new grade should have significantly lower creep.

[Southern_Man 0]

Mentosfresh

Interesting, I read that Spectra is not supposed to absorb moisture at all.

Spectra is used extensively in marine applications, so it is at the very least extremely resistant to moisture

"What if there were no hypothetical questions?"

[masterrigger1 2]

Quote

A new fiber to keep an eye on is the new Dyneema DM20. It is basically Spectra, but this new grade should have significantly lower creep.

You are a little behind. It has already been tried.
It actually is as bad as Spectra (Polyethylene) which is the worst line medium out there today.

The new stuff to look for is Twaron (Para-Aramid). One click better than Technora (Also a Para-Aramid...AKA "HMA") for parachute applications.

We are leading the way again, by being the first company to introduce Twaron line sets to the field with good results.

Also, Spectra shrinks from use.
The word "creep" is used in the braid world as a term for elongation due to loading the material from it's static state.
While it will get longer(elongate) when loaded, it gets shorter every time that you use it.
Probably the most misused, incorrect term for Spectra is that some people call it a "no stretch line", when in fact it does stretch when loaded.
It also is hygroscopic and will absorb water to some degree.

Some info for the masses:

Dacron - Polyester

Spectra - Polyethylene

Technora - Para-Aramid (which is in the HMA-High Modulus Aramid family)

Twaron - Para-Aramid (which is in the HMA-High Modulus Aramid family)

Cheers,
MEL

Skyworks Parachute Service, LLC
www.Skyworksparachuteservice.com

[erdnarob 1]

FYI Vectran is in the family of polyesther while Spectra is made of polyethylene fibers.

Learn from others mistakes, you will never live long enough to make them all.