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How can you estimate amount of jumps on main

 


Maksimsf  (B 37743)

Dec 11, 2012, 7:08 PM
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How can you estimate amount of jumps on main Can't Post

Question for riggers and experienced jumpers. If someone saying that main canopy got 500 jumps, but in reality it may be 1000 jumps or more - how can you tell? I do understand that 500 jumps in Arizona, Texas or SoCal may do more damage than 500 jumps somewhere up North. Is that just a matter of trust between seller and buyer?


labrys  (D 29848)

Dec 11, 2012, 7:29 PM
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Re: [Maksimsf] How can you estimate amount of jumps on main [In reply to] Can't Post

Quote:
Question for riggers and experienced jumpers. If someone saying that main canopy got 500 jumps, but in reality it may be 1000 jumps or more - how can you tell? I do understand that 500 jumps in Arizona, Texas or SoCal may do more damage than 500 jumps somewhere up North. Is that just a matter of trust between seller and buyer?

You've pretty much reaching the salient point in that it doesn't really matter how many jumps are on a main compared to its condition.

It matters what the condition of the main is. Something with 500 jumps that has been neglected and exposed to bad conditions won't have the same lifespan as something with 1000 jumps that's been well cared for in a good environment.

So why are you worried about the actual number of jumps more than the actual condition of the canopy?


davelepka  (D 21448)

Dec 11, 2012, 7:33 PM
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Re: [Maksimsf] How can you estimate amount of jumps on main [In reply to] Can't Post

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Is that just a matter of trust between seller and buyer?

If the buyer is dumb, sure. Otherwise, it's a matter of getting a qualifed rigger to inspect the gear and tell you how it looks.

My Velo has over 1000 jumps on it, but you couldn't tell by looking at the fabric. It's always been jumped in grassy Ohio and packed indoors. The lines are beat right now, and PD could tell you it's beed relined three times already, but the fabric looks great.

Always have used gear inspected by a rigger before purchase. It can save you $100s in repairs or maintenance, or from buying something that's not even airworthy.


Maksimsf  (B 37743)

Dec 11, 2012, 7:34 PM
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Re: [labrys] How can you estimate amount of jumps on main [In reply to] Can't Post

When you buy a canopy and if it's stated amount of jumps how can you estimate condition? That was my question.

Edit: Dave pretty much answered it :)


(This post was edited by Maksimsf on Dec 11, 2012, 7:36 PM)


councilman24  (D 8631)

Dec 11, 2012, 7:36 PM
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Re: [Maksimsf] How can you estimate amount of jumps on main [In reply to] Can't Post

You can't.

Before ZP canopies wore out by becoming porous and their flight characteristics degrading. We rarely replaced lines because the dacron line lasted the life of the canopy fabric. Roughly 700-1000 jumps.

Now, canopies made out of ZP material can last thousands of jumps and need several line sets. One that is jumped in the grass, always bagged, never left in the sun and with new lines might have 500 jumps or 1500 jumps. I doubt I could tell. Other things like DOM of the canopy and the rig it is in might add a clue. Fading of the canopy fabric also might add some hints. But neon fabric can fade quickly and my 1997 sabre neon rainbow with 800-1000 jumps essentially hasn't faded at all. Wear on other parts, bags, PC,s etc might also help. But all of these could be replaced. The wear on the label might give a hint but it would still be guess work and depend on the conditions where jumped.

And with ZP canopies it may not matter. The difference between 500 and 1000 jumps may simply be the need or not for new lines, bag or PC.

Don't misunderstand me. An abused canopy might go from worthy for purchase to junk in that 500 jumps. But it may have another 1000 left in it.

Overall condition of the fabric, tapes, lines and other components may be the real decision criteria instead of absolute number of jumps.

BTW I've never known anyone (other than meWink) to overestimate the number of jumps. Angelic


airtwardo  (D License)

Dec 11, 2012, 9:29 PM
Post #6 of 14 (1191 views)
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Re: [Maksimsf] How can you estimate amount of jumps on main [In reply to] Can't Post

In reply to:
Question for riggers and experienced jumpers. If someone saying that main canopy got 500 jumps, but in reality it may be 1000 jumps or more - how can you tell? I do understand that 500 jumps in Arizona, Texas or SoCal may do more damage than 500 jumps somewhere up North. Is that just a matter of trust between seller and buyer?

Just a quick point...I jump in Texas, I land on a manicured grass LZ and pack indoors...my main has 600 jumps on it and looks like new! Laugh


mark  (D 6108)

Dec 12, 2012, 5:56 AM
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Re: [airtwardo] How can you estimate amount of jumps on main [In reply to] Can't Post

In reply to:
Just a quick point...I jump in Texas, I land on a manicured grass LZ and pack indoors...my main has 600 jumps on it and looks like new! Laugh

Except the crossports. The crossports are frayed, especially the ones most outboard.

Mark


Premier likestojump  (D License)

Dec 13, 2012, 11:52 AM
Post #8 of 14 (883 views)
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Re: [Maksimsf] How can you estimate amount of jumps on main [In reply to] Can't Post

In short :

Crossport Fray (non-bearing ribs, especially center and end cells).

Damage on the bottom (both skins) at the trailing edge center (pinholes, tiny line burns)

top skin of the center cell from the PCA to the trailing edge - that's where most of the finger grease / sweat is rubbed off and that area will be very worn. As a bonus, a desert canopy will be very dusty, but that area will be much cleaner. An additional bonus is on a lighter colored canopy that area will looks faded / dirty and will most likely fail the pull test.

So yeah, it's possible to tell how much usage the canopy has had, even if the material looks relatively good.


airtwardo  (D License)

Dec 13, 2012, 12:00 PM
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Re: [mark] How can you estimate amount of jumps on main [In reply to] Can't Post

In reply to:
In reply to:
Just a quick point...I jump in Texas, I land on a manicured grass LZ and pack indoors...my main has 600 jumps on it and looks like new! Laugh

Except the crossports. The crossports are frayed, especially the ones most outboard.

Mark

Good point, I hadn't thought about that...but upon checking this morning the cross-ports look sharp & unfrayed...then again 1/2 of the jumps on that canopy are H&P's so I'd expect it to 'wear out' a little slower.

~I guess the point being, number of jumps isn't the only factor to be considered when looking at a used canopy.


swoopfly  (E License)

Dec 13, 2012, 11:03 PM
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Re: [airtwardo] How can you estimate amount of jumps on main [In reply to] Can't Post

I can usually get a decent rough average by feel of the zp fabric.
Even in good jump atmosphere the zp wears after every jump, just a little. The crossports and center cell also give you an idea like mentioned. Also how a canopy packs can give you an idea. They start getting broke in around 200 jumps. Add all these aspects together and i think you can come up with a close average.


Maksimsf  (B 37743)

Dec 14, 2012, 11:53 AM
Post #11 of 14 (763 views)
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Re: [swoopfly] How can you estimate amount of jumps on main [In reply to] Can't Post

Thanks guys, good info.


Premier Remster  (C License)

Dec 14, 2012, 11:58 AM
Post #12 of 14 (760 views)
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Re: [airtwardo] How can you estimate amount of jumps on main [In reply to] Can't Post

Quote:
I guess the point being, number of jumps isn't the only factor to be considered when looking at a used canopy.

Yep. After 7 years in Eloy, I doubt I'll get much for my Sam if and when I seel it! lol


Krip  (Student)

Dec 18, 2012, 10:09 PM
Post #13 of 14 (626 views)
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Re: [airtwardo] How can you estimate amount of jumps on main [In reply to] Can't Post

Quote:
Just a quick point...I jump in Texas, I land on a manicured grass LZ and pack indoors...my main has 600 jumps on it and looks like new! Laugh

There's lots of variables that can age a canopy besides # of jumps. In the PNW we never packed indoors, just under a nice tree in the shade, and flat packed it as soon as we landed on our carpet.

Jumping in Houston in the summer in houston Pirate packing inside is probably a good idea due to the heat not the UV.

Another thing that will age a canopy before its time is leaving it unpacked in the sun while you take a lunch breakCrazy Or leaving your rig in your car trunk for extended periods of time.

IMO you can tell a lot about a canopy by knowing the jumper your buying from and looking and feeling the canopy material.

We saw a canopy at the LP boogie that had a split thru the top of canopy's center cell. The nice lady said the dude that sold it to her told it it only had 500 jumps.

I'm not a rigger but we went for a lookie and we could tell from 10 ft away that the canopy was ragged out. It either had a mass qty of jumps on it or was used as a car cover. The fabric looked very dull and it felt paper thin.

Buying a used canopy is like buying a used carShocked. Have a rigger you trust check it out they can perform a objective tensil test on the material.

Wanna buy a 10 yr old car with 500 miles on it that was driven to church by a little old lady every xmas.Sly

Don't be afraid of buying used gear just be carefull what you buying.


pchapman  (D 1014)

Dec 19, 2012, 6:41 AM
Post #14 of 14 (559 views)
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Re: [Krip] How can you estimate amount of jumps on main [In reply to] Can't Post

In reply to:
Have a rigger you trust check it out they can perform a objective tensil test on the material.

With the caution that one had better agree with the seller about the tensile test and what number to test to!

If you rip the seller's canopy, you've probably just bought a ripped canopy for full price.

And it'll need some major repair work, even though it might have been good for hundreds of jumps more. The tear strength on the top aft center cell might be way down from spec, but still quite usable for a long time without a center cell replacement.

I've seen top aft center cells tested to just 20 lbs as a compromise value. Or skip the tensile test and use the opinion of an experienced jumper / rigger as to the value and expected future longevity of the canopy.


(This post was edited by pchapman on Dec 19, 2012, 6:42 AM)



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