Forums: Skydiving: Gear and Rigging:
550lb vs. 825lb microline

 

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jkwon  (A License)

Apr 5, 2004, 9:56 PM
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550lb vs. 825lb microline Can't Post

I figure the main difference is one is rated to 550 lbs and the other is rated to 825lbs...This leads me to believe one is thicker than the other. But how much force does someone who weighs 190lbs exert on his lines?? Am I safe buying 550lb lines??

--joe


nightjumps  (D 23385)

Apr 5, 2004, 10:05 PM
Post #2 of 29 (5418 views)
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Re: [jkwon] 550lb vs. 825lb microline [In reply to] Can't Post

Yes.


skygod7777  (D 24081)

Apr 5, 2004, 10:20 PM
Post #3 of 29 (5409 views)
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Re: [jkwon] 550lb vs. 825lb microline [In reply to] Can't Post

Quote:
This leads me to believe one is thicker than the other.


your thinking is correct.

Quote:
But how much force does someone who weighs 190lbs exert on his lines??

i'm not sure

Quote:
Am I safe buying 550lb lines??


yes, my buddy jumps a stilleto with 550, and he's about 225 or 230 out the door.


the only thing with the 550 is it goes out of trim faster than the 825. that is the downside to it.

later


KevinMcGuire  (D 15395)

Apr 5, 2004, 10:42 PM
Post #4 of 29 (5397 views)
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Re: [skygod7777] 550lb vs. 825lb microline [In reply to] Can't Post

550 also wears out much faster than 825. It is even more pronounced if you land in a dirt landing area


headoverheels  (D License)

Apr 5, 2004, 10:53 PM
Post #5 of 29 (5393 views)
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Re: [skygod7777] 550lb vs. 825lb microline [In reply to] Can't Post

In reply to:
the only thing with the 550 is it goes out of trim faster than the 825.

That was my belief, and maybe still is, but Brian Germain told me that the opposite is true. I still prefer the fatter lines. I wouldn't hesitate to buy a used canopy with either type, but would probably buy 825 for a new canopy or new line set.


skygod7777  (D 24081)

Apr 6, 2004, 12:35 AM
Post #6 of 29 (5371 views)
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Re: [headoverheels] 550lb vs. 825lb microline [In reply to] Can't Post

Quote:
That was my belief, and maybe still is, but Brian Germain told me that the opposite is true. I still prefer the fatter lines. I wouldn't hesitate to buy a used canopy with either type, but would probably buy 825 for a new canopy or new line set.


if this is the case, i'm sure brian will say something on here. he posts on here.


the guy who i said above (220 out the door) had to have his lines replaced at about 400 or 500 jumps with the 550, and i've seen the 825 go 800 or 900 +

later


cruzlite  (A 44192)

Apr 6, 2004, 3:01 AM
Post #7 of 29 (5352 views)
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Re: [skygod7777] 550lb vs. 825lb microline [In reply to] Can't Post

300 jumps with dacron (550)

15 with spectra(850)

I don't like the way the spectra stows (seems like a limp invitation to a half hitch)...
Don't like the small rubber bands...

Seriously considering dacron for next canopy...
D


grega  (D 100020)

Apr 6, 2004, 3:21 AM
Post #8 of 29 (5343 views)
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Re: [jkwon] 550lb vs. 825lb microline [In reply to] Can't Post

it seems a strange question to me but did you consider you actually have about 40 lines that's 22000 lbs at 550 lines and 33000 lbs at 825 lbs.

And i think human body can't survive forces that are even less than 22000 lbs. So yes either lines are strong enough, i think Wink


SkydiveMO  (D License)

Apr 6, 2004, 8:29 AM
Post #9 of 29 (5271 views)
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Re: [headoverheels] 550lb vs. 825lb microline [In reply to] Can't Post

In reply to:
In reply to:
the only thing with the 550 is it goes out of trim faster than the 825.

That was my belief, and maybe still is, but Brian Germain told me that the opposite is true.

Thats not what I want to hear Crazy. I just ordered a new canopy with 825lb microline with the hope it would wear better then the 550lb microline.

Does anyone know if 825lb microline causes significantly greater parasite drag compared to 550lb microline?


grega  (D 100020)

Apr 6, 2004, 10:10 AM
Post #10 of 29 (5239 views)
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Re: [SkydiveMO] 550lb vs. 825lb microline [In reply to] Can't Post

huh it sure does.

i don't know exatly how thick 550 lbs lines are but let's say they are 3mm in diameter and 825 are 4mm in diameter
826 lbs lines are about 1 mm wider than 550 lbs lines.
you have 40 lines, that are long 290 cm in average A lines probably around 270cm and D lines about 310cm (i don't know, i'm guessing according to my cobalt 120)

that's 4mm*40*290= 46400 square mm

with 550 lbs you'd get 3mm*40*290=34800 square mm

That's 33% more drag that you get from lines. if 825 lines are only 0.5 mm thicker than 550 (which definitely are) than it's only 16.7% more drag.

But we're talking only line drag not whole drag. You have a body that creates a lot more drag than the lines. just wear tight suits, and you'll swoop the same as in freefly suit with 550 lb lines Tongue


(This post was edited by grega on Apr 6, 2004, 10:11 AM)


jkwon  (A License)

Apr 6, 2004, 10:37 AM
Post #11 of 29 (5215 views)
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Re: [grega] 550lb vs. 825lb microline [In reply to] Can't Post

I didn't know I was opening up such a big discussion here. I would have to say that I didn't even think about line trim when I was making this decision. Does anyone know the true facts behind trim and which one goes out of trim faster? Sounds like some people believe the 550 goes out faster than the 825 and vice versa?

--joe


masterrig  (D License)

Apr 6, 2004, 11:57 AM
Post #12 of 29 (5189 views)
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Re: [jkwon] 550lb vs. 825lb microline [In reply to] Can't Post

Try giving PD, Precision or Icarus a call or an e-mail. I'll bet they will be able to tell you what you want to know.

Chuck


bch7773  (C License)

Apr 6, 2004, 12:56 PM
Post #13 of 29 (5169 views)
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Re: [masterrig] 550lb vs. 825lb microline [In reply to] Can't Post

and if anyone does call them up, post what they say on here... i'm kinda curious now to see the "official" answer


SkydiveMO  (D License)

Apr 6, 2004, 1:24 PM
Post #14 of 29 (5157 views)
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Re: [grega] 550lb vs. 825lb microline [In reply to] Can't Post

In reply to:
But we're talking only line drag not whole drag. You have a body that creates a lot more drag than the lines. just wear tight suits, and you'll swoop the same as in freefly suit with 550 lb lines

Which leads me back to the question is the difference in line drag of 550 vs. 825 significant? I was wondering if the drag from everything else (slider, pilot-chute, jumpers body, wing itself, etc.) so great that it makes the difference between 550 and 825lb microline even noticeable?


mjosparky  (D 5476)

Apr 6, 2004, 2:08 PM
Post #15 of 29 (5140 views)
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Re: [SkydiveMO] 550lb vs. 825lb microline [In reply to] Can't Post

In reply to:
Which leads me back to the question is the difference in line drag of 550 vs. 825 significant? I was wondering if the drag from everything else (slider, pilot-chute, jumpers body, wing itself, etc.) so great that it makes the difference between 550 and 825lb microline even noticeable?

The 825 will create more drag than the 550 but you don't have access to the equipment that can measure the difference.Tongue
Sparky


SkydiveMO  (D License)

Apr 6, 2004, 3:30 PM
Post #16 of 29 (5108 views)
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Re: [mjosparky] 550lb vs. 825lb microline [In reply to] Can't Post

In reply to:
The 825 will create more drag than the 550 but you don't have access to the equipment that can measure the difference.Tongue
Sparky

I do have access to the equipment needed to measure it Cool however going through all the trouble to design the experiment and controls to test this would go against my lazy nature. I was hoping for the easy answer, like has anyone had 825 microline on their canopy then had it relined to 550 microline and said Wow! That made one heck of a difference!

http://www.pcprg.com


mjosparky  (D 5476)

Apr 6, 2004, 4:37 PM
Post #17 of 29 (5089 views)
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Re: [SkydiveMO] 550lb vs. 825lb microline [In reply to] Can't Post

In reply to:
like has anyone had 825 microline on their canopy then had it relined to 550 microline and said Wow! That made one heck of a difference!

If you have access to the equipment and have tested with it in the past, you already know the answer.Tongue Right?
Sparky


darkwing  (D 4164)

Apr 6, 2004, 4:43 PM
Post #18 of 29 (5087 views)
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Re: [SkydiveMO] 550lb vs. 825lb microline [In reply to] Can't Post

the quick answer for cylinder drag is that it is proportional to the presented area. Assuming the cross-sectional area of the line scales with its rated strength we determine that the 825 has 22% greater diameter than the 550 (if you care-- Sqrt(825/550)=1.22). So, for lines of the same length, the 825 will have 22% more frontal area, hence 22% more drag. I agree though that it is small potatoes compared to all the other drag factors, and isn't worth worrying about unless you are greased up, bare naked, have a disposable pilot chute and d-bag, and are shooting for a record.


SkydiveMO  (D License)

Apr 7, 2004, 5:49 AM
Post #19 of 29 (5022 views)
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Re: [darkwing] 550lb vs. 825lb microline [In reply to] Can't Post

In reply to:
I agree though that it is small potatoes compared to all the other drag factors, and isn't worth worrying about unless you are greased up, bare naked, have a disposable pilot chute and d-bag, and are shooting for a record.

That's what I was wondering! Sure I could sit down and calculate everything out but in the end what I wanted to know is under canopy could I feel the difference?

In reply to:
If you have access to the equipment and have tested with it in the past, you already know the answer. Tongue Right?

Its funny, you can spend all day calculating how a parachute should open and fly then you throw it out of an airplane and it does something completely different. I let the professor handle the calculations I just like to push stuff out of airplanes and see if they open PirateWink


darkwing  (D 4164)

Apr 7, 2004, 7:00 AM
Post #20 of 29 (5009 views)
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Re: [SkydiveMO] 550lb vs. 825lb microline [In reply to] Can't Post

In reply to:
Its funny, you can spend all day calculating how a parachute should open and fly then you throw it out of an airplane and it does something completely different. I let the professor handle the calculations I just like to push stuff out of airplanes and see if they open PirateWink

I agree, it is just that very often people don't believe you without the numbers. Numbers are great, but until you fly it, the simulations won't really answer all of the questions.


jkwon  (A License)

Apr 7, 2004, 8:25 AM
Post #21 of 29 (4992 views)
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Re: [SkydiveMO] 550lb vs. 825lb microline [In reply to] Can't Post

I had another experienced jumper tell me that the 825 lines wear faster than the 550 lines. ???

I'm guessing it has something to to with total surface area actually contacting the grommets of the slider. That has to be the only explanation.

--smiley


skymoo  (D 26277)

Jan 18, 2007, 1:51 PM
Post #22 of 29 (4173 views)
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Re: [jkwon] 550lb vs. 825lb microline [In reply to] Can't Post

Rusty, very nice guy at PD, confirms that the 825lb microline lasts longer than the 550lb microline. "they are thinner and have less weave, any nick or scratch percentagewise will wear out the line more" now, the advantage is confirmed to be less drag, but in his words "only the very advanced canopy pilots" have use for this slight difference. I'm sticking to 825s

Yup, it took three years to answer this Tongue


(This post was edited by skymoo on Jan 18, 2007, 3:17 PM)


everymansaved  (C License)

Jan 18, 2007, 5:22 PM
Post #23 of 29 (4122 views)
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Re: [jkwon] 550lb vs. 825lb microline [In reply to] Can't Post

If trim is a big conern, go with Vectran (assuming it's offered on the canopy you want). You have to replace it more often, but it never loses trim.

EFS
Sean LR


Premier Tonto  (D 515)
Moderator
Jan 19, 2007, 12:26 AM
Post #24 of 29 (4068 views)
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Re: [SkydiveMO] 550lb vs. 825lb microline [In reply to] Can't Post

In reply to:
has anyone had 825 microline on their canopy then had it relined to 550 microline and said Wow! That made one heck of a difference!

No, but I went from 550 to 825 on a reline, and thought "Wow! That made one heck of a difference!" I noticed an increase in performance. Amazing what being it trim will do to a canopy.

t


RMURRAY

Jan 19, 2007, 2:16 AM
Post #25 of 29 (4052 views)
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Re: [everymansaved] 550lb vs. 825lb microline [In reply to] Can't Post

In reply to:
If trim is a big conern, go with Vectran (assuming it's offered on the canopy you want). You have to replace it more often, but it never loses trim.

EFS
Sean LR

exactly. I would not reline any canopy with spectra these days...

rm


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