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pressuremedia

JVX - loose lines on opening??

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Hey whats up Jim.
Where are you jumping now, you missing the Zone?? :)
I heard you had some problems with your jvx openings.
I've had 3 jvx's and they all opened really well, soft but always with tension on the lines.
But, I had an 89vx with jvx lineset and the C's and D's would flap around during opening, I had two chops because of tension knots on it.
Is it the same lines that are flapping on your wing?

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doing well Ricky. will pm you with a lot more.

Jumping a zp 90JVX
Yes, these lines are flapping around. Changed slider a few times and now not getting the tension knots (yet - a few before) but a lot more flapping lines.

All of your JVX's opened without flapping lines???

Anyone with a JVX and flapping lines?

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Hi Jim,

I havn't noticed any lines flapping aroud on mine!

To be honest I haven't really been looking though. I have a look this weekend.

Hows the careere change going?

charge on

rhyso
"When the power of love overcomes the love of power, then the world will see peace." - 'Jimi' Hendrix

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How many jumps do you have on your JVX?

You need to change your lineset around 250 - 400 jumps. That's one of the reasons they come with a spare line set.

If you're below those numbers, you have a problem.



is it the original lineset or was it relined....maybe the reline job is the problem. I would talk directly to Jim S about it.

rm

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How many jumps do you have on your JVX?

You need to change your lineset around 250 - 400 jumps. That's one of the reasons they come with a spare line set.

If you're below those numbers, you have a problem.


That makes no sense what so ever. How is changing to the exact same lineset going to change the amount of slack line he's experiencing? It's HMA, it changes less than 1/2" in a 1000 jumps.
----------------------------------------------
You're not as good as you think you are. Seriously.

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I'll yield to your experience with JVX's and their Trim Sets. I assume you jump them and understand every aspect of them? But hey thanks for the Flame.

I was not stating that this alone was his problem, but he should take jump numbers into consideration if he has more than 400 jumps on a JVX line set.

It could be that he simply has a poorly trimmed line set, and should take that up with Jim if less than 250 jumps.

You can't assume that all HMA lines are constructed the same way and wear at the same rate. You also cannot say that HMA will only wear up to a 1/2 inch in 1000 jumps. You can't state that because many things alone or in combination contribute to line wear and shrinkage or taking a line set out of trim.

We don't know if he has a stock slider, brass or steel slider gromets, or even a knick in one of his grommets. He could have shortened his control lines, or he could just have a bad line set. We don't know.

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Harry, it has nothing to do with JVX or any other canopy. It's the suggestion that the opening issues are due to worn or "out of trim" HMA lineset that's incorrect. HMA offers some of the best dimensional stability compared to any other line type, it doesnt shrink or go out of trim, at least not sooner then the lines break due to wear and tear :) That is one of the reasons it has become a popular choice for high performance wings.

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Yes I know what's adverstised with regard to HMA, and agree with it for the most part. I agree that HMA is more likely to break than streatch when they are worn, but I don't believe that HMA lines never go out of trim.

Even 1/2 inch out of Trim on A-D lines on a JVX can affect performance. Probably not so much on the control lines.

The OP did not specify how loose his lines were. But I'd agree that if they were significantly loose (4-6") then it's probably a line trim issue or a Control Line setting issue.

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they are vectran lines not HMA. The JVX has 3-400 jumps on. The lineset has not been changed. The JVX was one of the first ones and came with the four flap slider. Since then the brake lines have been changed according to an update and the slider is the correct size with no flaps. Line trim has been checked and does not seem to be out at all.

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I too have a zp jvx90 with vectran lines and am experiencing the same loose lines during opening; Specifically it is most drastic just before the slider starts to move down. My lines have around 150 jumps, and I have videos showing this on essentially every opening. When these lines decide to not knot up (happend twice in 150 jumps), the openings are simply amazing; non seaking snivel with center cell inflation spreading out to the endcells, easily staying on heading. This canopy is DOM feb. 2006.

I can post videos with frames showing rogue loose lines forming randomly during inflation upon request.

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Specifically it is most drastic just before the slider starts to move down



I have not noticed this but wonder if it is the slider not moving off the stops "cleanly". I have had a bunch of wild rides which seem to start right at that point. Maybe MEL could comment?

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Here is a sample of of 6 openings. Despite what the lines are doing, all of these opened beautifully soft and on heading.

I apologize for the lack of quality of these photos. Just switched to mac, and imovie is refusing to work with anything that touched sony vegas. Screenshots are the best that I could get. Btw I am a very neat packer, and initial snivels show no slack lines on any of these openings.

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Thats what I thought. Is anyone seeing this on other hp canopies, or is this specifically jvx? I love this canopy, and would hate to change due to increased malfunction rate; my only cutaway was a tension knot after an ideal snivel on this canopy. I also only noticed this after reviewing videos, and have never seen it during jumps.

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I have not noticed this but wonder if it is the slider not moving off the stops "cleanly". I have had a bunch of wild rides which seem to start right at that point. Maybe MEL could comment?



Sorry, just saw this post! I am still in Reno had just had a moment to log on....


The lines are loose because of exactlt what Aggie spoke of. The canopy has not yet pressurized fully and extended the line.

With Technora this becomes an issue as the slider is trying to come downward, causing excess BELOW the slider of the not yet extended lines. Technora has a lot of "grip" in reference to the slider.


BS,
MEL
Skyworks Parachute Service, LLC
www.Skyworksparachuteservice.com

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These lines are vectran



Vectran would usually act the same as it is not as smooth as Spectra.

Even more so if it is a little worn. As it wears, it becomes more like Technora as far as grip in relation to the slider grommets.

A high aspect ratio canopy is short on chord and long on wing span.

So during inflation is is going to inflate from the center out during a normal opening (hopefully).

The only way to reduce the delay the inflation of the end cells is to open up the crossports WHICH is NOT recommended.

Cheers,
MEL
Skyworks Parachute Service, LLC
www.Skyworksparachuteservice.com

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Is there any line type you would recommend to minimize this problem? These lines are still quite new to feel and appearance, with little wear to the lines and grommets.



No, not really.

I would suggest looking at how you pack and maybe try something a little different to speed up the end cells inflation process.

Cheers,
MEL
Skyworks Parachute Service, LLC
www.Skyworksparachuteservice.com

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