HMA lines.....whats the 411....

[Vectracide 0]

I am not that far from a lineset change and I am considering using a HMA set. Can a guy get a HMA lineset for a Crossfire 2 or a Katana? Other than the fact that they last longer than Vectran and present less wind resistance, whats the other benefits?

Edit to add: After posting I did a search.........and found that it has been done.

I guess my question should be now...is it worth it for the Katana that will be a competiton canopy? Or even the Xfire2 for shits and giggles?

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Controlled and Deliberate.....

[BETO74 0]

I used to fly a Nitron 135 with HMA lines, yes is less drag, do you notice it? no really. Because they are so much thinner than the other lines the risks of tension knots increases, I had two tension knots one I landed rear riser no problems the other was a cut away. In my opinion unless you're in the high end of canopy piloting you will not feel the difference in drag or get much out it. Another thing I don't really understand is the tendency of some canopy manufactures to have HMA lines on student canopies maybe somebody can explain that to me, on a high performance regardless of my opinion I can understand since the people buying this canopies have more experience and they understand the risk involve but why students?

http://web.mac.com/ac057a/iWeb/AC057A/H0M3.html

[marks 0]

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do you notice it? no really.

you notice a HUGE difference, if you are flying a VERY high performance canopy.

every time you double your speed, you triple your drag.

try driving down the highway at 90 mph, and hold a 10 ft long 2x4 out the window note how much drag there is, then turn the 2x4 sideways, and feel the reduction in drag. thats approximately the difference between the SMALL HMA," there are different sizes". and vectran.

and there is a increase in tension knots, you have to stow lines very very neat.

[marks 0]

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Another thing I don't really understand is the tendency of some canopy manufactures to have HMA lines on student canopies maybe somebody can explain that to me,

a large benefit of hma, is it doesn't go out of trim like the other lines do.


and also, just because it is hma doesn't mean it is the small ones, there are different sizes.

[beezyshaw 0]

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every time you double your speed, you triple your drag

Actually, Mark, if you double speed you quadruple the drag. Drag increases as the square of the speed, meaning if you triple your speed, drag is increased 9 times.

[BETO74 0]

Agree!!!
I believe that only those that have master canopy piloting to that extreme benefit from thinner lines (HMA). does the regular weekend warrior notice that difference in speed, I believe not.

Yes they require to be more careful while stowing the lines, learn that one the hard way!

http://web.mac.com/ac057a/iWeb/AC057A/H0M3.html

[johnny1488 1]

I cant vouch for non cascaded, but I doubt cascaded HMA would last as long as a vectran line set.

Icarus recommends 5-700 jumps on a line set. I change my brake lines at 300 and have seen more than 1000 jumps on a line set without a line braking. and because it is vectran, it stays in trim very well.

Like was said, unless you are at the very top of the swooping ladder, you probably dont need an HMA line set.

Johnny
--"This ain't no book club, we're all gonna die!"
Mike Rome

[Vectracide 0]

So, by the jist of the replies, it looks like there isn't much of a benefit for me for where I'm currently at. Perhaps, its more of a liability with the potenital tension knots and attention to stowing needed. I'll stick with Vectran. Besides, its my call here anyways..,. Thanks.

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Controlled and Deliberate.....

[BETO74 0]

I thought the HMA lines don't strech or shrink thats why the trim last longer, much different tahn vectran you can also see the wear on a vectran line the HMA line just snaps. Maybe somebody could elaborate more.

http://web.mac.com/ac057a/iWeb/AC057A/H0M3.html

[marks 0]

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the HMA line just snaps.

I think HMA has a bad rap of snapping because the peeps using them are useing the tiny small HMA.

there are different seizes of HMA, I would think the thicker HMA is stronger than a similar sized vectran line.

beezy, more info....

[diablopilot 2]

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much different tahn vectran you can also see the wear on a vectran line the HMA line just snaps. Maybe somebody could elaborate more.

Untrue. HMA shows wear as well.

----------------------------------------------
You're not as good as you think you are. Seriously.

[johnny1488 1]

HMA and vectran have similar line trim characteristics. Both stay in trim very well over the life of the line set.

Johnny
--"This ain't no book club, we're all gonna die!"
Mike Rome

[masterrigger1 2]

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I cant vouch for non cascaded, but I doubt cascaded HMA would last as long as a vectran line set.

Johnny,
Being casscaded are not has absolutely nothing to do with the longevity of the lines.

It is how it is sewn and whether or not it has UV protection on the line material. A standard bartack is not to be used for smaller HMA material.

We have some line sets (Blue Colored Technora)
going through 1200 jumps with no breakage vs.
earlier non-colored breaking anywhere from 200 to 600 jumps.


MEL

Skyworks Parachute Service, LLC
www.Skyworksparachuteservice.com

[beezyshaw 0]

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I think HMA has a bad rap of snapping because the peeps using them are useing the tiny small HMA.

there are different seizes of HMA, I would think the thicker HMA is stronger than a similar sized vectran line.

beezy, more info....

The HMA just breaking with no warning is sort of like an urban legend; the story just keeps being passed on and on. Like JP said, it does show wear, it's just that you have to look at it a little more carefully to see the questionable areas. I have seen many many Nitro canopies with well over a thousand jumps on the lineset. One thing I have noticed about HMA in my years of manufacturing with it is that it is imperative to get the slider down onto the risers. I have replaced a few outboard lines way too early in cases where the jumper chooses to leave their slider riding above the risers.

While I don't have any personal experience with cascaded HMA, I have talked to riggers at PD that build the comp. linesets for Velocities. They've told me that the fibers begin to separate at the cascade, as the aramid doesn't do well with the side-load imposed by the cascades.

As to the tensile strength of HMA vs. Vectran of similar bulk, I'd say HMA would be about 15% stronger. In other words, a 600 lb. HMA is about the same size as 500 lb. Vectran. One more note about Vectran vs. HMA (Technora) concerning dimensional stability. HMA will stay in near perfect trim, and while Vectran will not shrink like Spectra, it does elongate over time. But it does tend to get longer fairly evenly across the lineset, which for all practical purposes does not present a trim issue. A vectran lineset with 500 jumps will be about an inch and a half longer than when it was new.

[masterrigger1 2]

Beezy,
I guess we differ in our findings somewhat. It could be from the different types of braid of Vectran, etc

What I typically find is The 580 Vectran that we have been using for the last 4 years is about 1/2 inch of elongation in 600-800 jumps on sport canopiesa and about 3/4 inch on tandems.

While I do not measure all old line sets, the ones that I have measured where all within the numbers specified above.

A good test of this is to measure the Inside A line and inside C line when you have a new line set installed or a new canopy.
Jot that measurement down somewhere safe. Then before you send it out for a reline measure the same lines again.

A quick note, the inside C (center cell) lines will elongate the most on both Vectran and Technora.

As far as Tecnora, The 340 lb that we put on stretches pretty much the same as Vectran but not any more than that.

We have been taking measurements on all removed Technora linesets for R&D.

You are right as to the elongation being somewhat uniform, alot more than the shrinkage of Spectra!

Lastly, all line material is weaker when side loaded.

With that said, We have NEVER had a failure at a casscade point, as far as I know! So I would say the casscade issue is a moot point.

BS,
MEL

Skyworks Parachute Service, LLC
www.Skyworksparachuteservice.com

[BlindBrick 0]

Just out of curiosity, I know that there are now several different flavors of HMA out there, from the stuff PA uses, to MEL's stuff to a custom braid that a dz.commer had made. What's the spec's ont he differing flavors. ie strengths and dimensions?

-Blind

"If you end up in an alligator's jaws, naked, you probably did something to deserve it."

[skydived19006 4]

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With that said, We have NEVER had a failure at a casscade point, as far as I know! So I would say the casscade issue is a moot point.

BS,
MEL

I recently chopped my first tandem main (going on 2000 tandems, me not the canpy). My Vectran lined Icarus 330 had both center A/B lines break just below the cascade, right where the inserted line stopped. Was this a failure "at the cascade point", or below the cascade?

I've decided to make an attempt to keep a better eye on my Vectran lines. I'd guess that this canopy had in the range of 300 to 400 jumps on it. We're in grassy Kansas, not much sand abrasion.

About 7 years back, I had another Vectran line break on an Icarus 365. That failure was at the top of the A/B cascade on the center cell. I lost the B line, and landed the canopy. Was that a failure of/at the cascade?

Martin
Air Capital DZ

Experience is what you get when you thought you were going to get something else.

AC DZ

[masterrigger1 2]

Martin,
I would like to see the lines if you still have them.

That goes for anyone that may come across that same situation also!

Thanks,
MEL

PS - See if you can keep a jump total going with the canopy we just sent back to you. It would be nice for reference later down the road.

Skyworks Parachute Service, LLC
www.Skyworksparachuteservice.com