New lines?

[peckerhead 0]

Maybe I am old fashioned but I keep hearing about "new linesets"

Back in the day we never replaced a line unless it broke.

Now I hear about people replacing lines that are not broke with as few as 100. 200, 300, 400, etc. jumps.

A few months ago this kid brings me a rig that he wants to sell and he says "The canopy only has 200 jumps but it need new lines"

I looked at it and jumped it and said...

What?



Is this really necessary? Or do you just do it because someone told you it was the cool thing to do?

The new motto seems to be:

If it aint broke then fix it anyway

[2shay 0]

I would guess every 500 for lines and trim mostly but then again I suppose I should have relined mine a while ago but I still love it and feel no need to so what the hell, I don't know.

don't try your bullshit with me!!!

[DougH 270]

I think it depends on the canopy. When I first got my hornet 170 it had around 150? jumps or so. It was opening like a lightening bolt so the slider was flying down the lines at light speed.

It is severly out of trim now with only 350 jumps. I measured it, scary out of trim.

I think if it was packed to open more slowly it would have experinced a lot less shrink in the spectra lines. Just a hunch.

"The restraining order says you're only allowed to touch me in freefall"
=P

[AggieDave 6]

Seriously? Have you ever checked the line trim on a canopy and found it out of trim?

Do you know how the different line types respond to the friction and wear from openings?

Depending on the types of lines on a canopy, a canopy can get way out of trim long before the lines break from wear. On a modern canopy design that can result in very odd flight characteristics, bad openings or even dangerous situation with the canopy's stability in flight.

--"When I die, may I be surrounded by scattered chrome and burning gasoline."

[kenneth21441 0]

In my oppion:

I feel that a canopy that has a high wing load will need a new line set sooner then one that has been jumped with a lighter wing load factor.

Based on this I feel that this information plus the other factors of packing methods (IE: pro, stack, rolling, etc) along with actual opening speeds each have on the canopy and lines.

An example that I might use is a 200 lb jumper exiting with a canopy with 130 cu ft of canopy (High wing load) vs 200 lb jumper with a 250 cu ft canopy (lighter wing load).. The amount of stress on the materials would be greater then a lighter wing load. I have seen this on heavy equipment airdrops while in the Army.

Such in the case of a one to two parachute load: if you use two parachutes for say 8000 lb load and one system opens sooner (2Sec cutters) this one parachute is holding the entire shock/ load for that 2 sec. I have seen this many times including with the higher load base loads of 42K.

What goes first canopy or lines: not sure as its a mess. Blown gores/ panels, and broken/ snapped lines.


Just my in put in this area....

Kenneth Potter
FAA Senior Parachute Rigger
Tactical Delivery Instructor (Jeddah, KSA)
FFL Gunsmith

[skybytch 259]

Quote

Back in the day we never replaced a line unless it broke.

Back in the day we jumped big slow F111 canopies with Dacron lines. By the time the lines needed replacing, the canopy was either sold to a broke newbie who didn't know any better or retired to become a car cover or wall hanging.

We don't all jump big F111 canopies with Dacron lines anymore. We get less drag by using different materials for lines; the tradeoff is that those lines don't last (stay in trim, don't break) the way Dacron does.

[peckerhead 0]

Agreed. Obviously if it is out of trim or there is a justifiable reason then replacement is waranted.

What I am talking about is random replacement for no reason other than someone says you should.

The canopy I mentioned above was not out of trim and opened just fine. Not to mention there was very little signs of wear.

[skybytch 259]

Quote

What I am talking about is random replacement for no reason other than someone says you should.

The canopy I mentioned above was not out of trim and opened just fine. Not to mention there was very little signs of wear.

Some people have more money than sense. It's good to help them fix that imbalance.

[VideoFly 0]

I checked my line set after my openings began to shift off heading. At 700 jumps on the canopy, some of my lines were three inches too short, so I changed them. The canopy flies much better now.

[DrewEckhardt 0]

Quote

Is this really necessary?

Spectra shrinkage is significant. IIRC there was a > 5" difference between the outer lines of my Stiletto 120 and inner lines due to shrinkage after 600 jumps. Openings were getting more interesting for 100-200 jumps before that even with a brake line replacement.

[phastasphuk 0]

Quote

In my oppion:

I feel that a canopy that has a high wing load will need a new line set sooner then one that has been jumped with a lighter wing load factor.

Based on this I feel that this information plus the other factors of packing methods (IE: pro, stack, rolling, etc) along with actual opening speeds each have on the canopy and lines.

An example that I might use is a 200 lb jumper exiting with a canopy with 130 cu ft of canopy (High wing load) vs 200 lb jumper with a 250 cu ft canopy (lighter wing load).. The amount of stress on the materials would be greater then a lighter wing load. I have seen this on heavy equipment airdrops while in the Army.

Putting the new way of measuring canopy size away, why would a canopy with a high wingload be subjected to more stress on the lines than a canopy with a light wingload? Both are subjected to the same load. And if that was the case wouldnt we see more small canopies blow up than big ones, and also put lines with a higher rating on the pocketrockets...but in reality it is the opposite (well maybe not for the blown chutes, anyone know?).

But I agree that highly loaded canopies get new lines more often, most likely because the effects of lines being out of trim are more noticable on such canopies.

chris

[dontiego 0]

Quote

Putting the new way of measuring canopy size away, why would a canopy with a high wingload be subjected to more stress on the lines than a canopy with a light wingload? Both are subjected to the same load. And if that was the case wouldnt we see more small canopies blow up than big ones, and also put lines with a higher rating on the pocketrockets...but in reality it is the opposite (well maybe not for the blown chutes, anyone know?).

Well, in theory you're right: whatever how big the canopy, your weight is divided in 40 pieces, supported by every 40 lines.
This is valid in flight with constant speed and direction
(this is why I still don't understand why people say you have to use a larger canopy to do a Mr.Bill, because of the increased weight).

In spirals however, you get to add the Gs to your weight. A smaller canopy gives you more Gs, so the lines endure more strength.


(I guess?)

"We call on the common man to rise up in revolt against this evil of typographical ignorance."
http://bancomicsans.com

[UDSkyJunkie 0]

Quote

What I am talking about is random replacement for no reason other than someone says you should.

The canopy I mentioned above was not out of trim and opened just fine. Not to mention there was very little signs of wear.

Yeah, I think some people are a little OCD about their lines... or they think the fast/slow/off-heading/weird/diving/twisted openings are the result of the canopy being 1/2 inch out of trim instead of poor packing, poor body position, dumping in a track, or just the fact that most canopies don't open perfect every time.

I bought a Sabre1 135 from someone who re-lined it 4 or 5 times in (tops) 500 jumps... if he had a slammer he'd send it back to PD. I put another 500 jumps on it, and it flies just fine thank you very much, although it is about 3-4 inches out of trim. Opening and flight charachteristics did not change all that much. (although I did replace the lower brake lines due to wear).

Obviously if you're jumping a Widowmaker 37 with ultra-tiny carbon-nanotube lines you probably need to replace them a lot more. I think for most of us though every 500-1000 jumps is plenty.

"Some people follow their dreams, others hunt them down and beat them mercilessly into submission."

[UDSkyJunkie 0]

Quote

(this is why I still don't understand why people say you have to use a larger canopy to do a Mr.Bill, because of the increased weight).

I have an answer for this, and it's nothing to do with the possibility of damaging the canopy.

After several "interesting" openings and more than one malfunction, a couple of jumpers I know decided that they shouldn't use tiny, elliptical canopies for Mr Bill dives. I think they were using a 119 crossfire 2.

It's not that the canopy is likley to blow up due to the increased force (the hanger won't stand a chance of holding on if the opening is that hard anyway), it's that the 3:1+ loading will exaggerate any ansymmetrical aspect of the opening, greatly increasing the likleyhood of violent spins, ect. The 2nd person not being hooked up in the harness directly, and the fact that the deployment was probably from a less than stable position further exaserbates the problem.

"Some people follow their dreams, others hunt them down and beat them mercilessly into submission."