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Packing with smaller rubber bands or just double loop?

 

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vanessalh  (D 33301)

Nov 5, 2012, 7:27 AM
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Packing with smaller rubber bands or just double loop? Can't Post

I just purchased gear, and am discovering the joys of breaking your own rubber bands. I notice they are typically sold in two sizes (large and small). I can only assume the smaller ones are used for the stows further down the bag.

Up until now I've been double looping the large bands to get sufficient tension on the lines. Should I instead be using the smaller bands here?

Does it make a difference on opening?


DocPop  (C License)

Nov 5, 2012, 7:32 AM
Post #2 of 29 (1677 views)
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Re: [vanessalh] Packing with smaller rubber bands or just double loop? [In reply to] Can't Post

Advice from the PD reps at Summerfest this year was for me to ditch the small bands for the locking stows and double wrap large ones as the keep the canopy from moving around better as the bag accelerates off your back.

The above was for HMA lines but would hold true for Vectran and Microline (Spectra). Not sure what the advice would be for dacron.

Non-locking stows - do whatever you want as long as they all release their lines at the same tension. They really just keep things neat during the packing process.


davelepka  (D 21448)

Nov 5, 2012, 7:32 AM
Post #3 of 29 (1677 views)
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Re: [vanessalh] Packing with smaller rubber bands or just double loop? [In reply to] Can't Post

Quote:
Does it make a difference on opening?

No. Your opening is a function of your pack job, airspeed, and body position. Rubber bands have nothing to do with that. Some will try to argue that proper tension is required, but reserves (besides Racers) and a good number of main D-bags only have locking stows, with no rubber bands at all holding the bulk of the lines.

Provided that your lines are neatly stowed in some way, and all the stows balanced in their size and tension, it will not effect your opening.

In terms of size, I use the big ones double wrapped. They're easier to wrap, and easier to change, and I just like them better.


Fast  (D 28237)

Nov 5, 2012, 7:49 AM
Post #4 of 29 (1637 views)
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Re: [DocPop] Packing with smaller rubber bands or just double loop? [In reply to] Can't Post

In reply to:
Advice from the PD reps at Summerfest this year was for me to ditch the small bands for the locking stows and double wrap large ones as the keep the canopy from moving around better as the bag accelerates off your back.

The above was for HMA lines but would hold true for Vectran and Microline (Spectra). Not sure what the advice would be for dacron.

Non-locking stows - do whatever you want as long as they all release their lines at the same tension. They really just keep things neat during the packing process.

Ya know - I have heard that as well. I even watched the video, so did the packers I use. One of them had tight enough double stowed lines that I was getting stood up before the parachute was even remotely out of the bag, causing me to speed up and subsequently have harder openings.

Packing is like voodoo half the time.... bleh


DocPop  (C License)

Nov 5, 2012, 7:52 AM
Post #5 of 29 (1631 views)
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Re: [Fast] Packing with smaller rubber bands or just double loop? [In reply to] Can't Post

I have to say that I feel like my openings have improved using the PD advice - but it's very subjective and I was looking for ways to speed up my openings anyway.

I use a semi-stowless bag with only two locking stows, FWIW.


pchapman  (D 1014)

Nov 5, 2012, 8:30 AM
Post #6 of 29 (1594 views)
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Re: [vanessalh] Packing with smaller rubber bands or just double loop? [In reply to] Can't Post

In reply to:
Does it make a difference on opening?

Note that Davelepka said "no", but also said, "provided that..." It is those details that are important!


vanessalh  (D 33301)

Nov 5, 2012, 8:51 AM
Post #7 of 29 (1570 views)
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Re: [pchapman] Packing with smaller rubber bands or just double loop? [In reply to] Can't Post

Thanks all!
Since it doesn't make a difference either way it seems easiest just to use the large bands and double loop them.

On the voodoo of packing... has anyone else had the experience where packers give you harder openings than your own pack?

It happens to me constantly, to the point that I've decided to pack for myself all the time. It might not look elegant going into the bag, but I get a great opening so something must be working...


theonlyski  (D License)

Nov 5, 2012, 9:30 AM
Post #8 of 29 (1538 views)
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Re: [vanessalh] Packing with smaller rubber bands or just double loop? [In reply to] Can't Post

In reply to:
On the voodoo of packing... has anyone else had the experience where packers give you harder openings than your own pack?

Must be your body position! Tongue


You pay for the pack job, NOT the opening.Wink


(This post was edited by theonlyski on Nov 5, 2012, 9:30 AM)


JohnSherman  (D 2105)

Nov 5, 2012, 9:43 AM
Post #9 of 29 (1522 views)
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Re: [vanessalh] Packing with smaller rubber bands or just double loop? [In reply to] Can't Post

One more thing, You might find the following interesting. They should be read sequentially as that is the order of development:

http://www.jumpshack.com/...ds&SortBy=DATE_D

http://www.jumpshack.com/...OW&SortBy=DATE_D

http://www.jumpshack.com/...ag&SortBy=DATE_D

http://www.jumpshack.com/...ag&SortBy=DATE_D

Our conclusion was that if the line stows are balanced then only one size of rubber band is required, from small diameter line to heavy line and none require double wraping.


adamUK  (C 104423)

Nov 5, 2012, 9:49 AM
Post #10 of 29 (1517 views)
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Re: [davelepka] Packing with smaller rubber bands or just double loop? [In reply to] Can't Post

Quote:
Some will try to argue that proper tension is required

I remember being told that it was good practice to have at least 12lb of tension to release each stow (i.e. you should be able to pick the bag up using the lines and the stow would hold). Is this not true? What would happen if I had no tension on all the stows with the exception of the mouth locks, would the opening still be okay?

I've taken a much greater interest in my packing since I had my 'Mike Tyson' slammer PirateUnsureFrown so all thoughts welcome!

Cheers All

Adam.


davelepka  (D 21448)

Nov 5, 2012, 10:07 AM
Post #11 of 29 (1506 views)
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Re: [adamUK] Packing with smaller rubber bands or just double loop? [In reply to] Can't Post

Quote:
I remember being told that it was good practice to have at least 12lb of tension to release each stow (i.e. you should be able to pick the bag up using the lines and the stow would hold). Is this not true? What would happen if I had no tension on all the stows with the exception of the mouth locks, would the opening still be okay?

Again, most every reserve and all 'stowless' main d-bags are just as you decsribed. Locking stows only, with the rest of the lines folded into a pocket or pouch, and they open fine.

The point is that rubber band tension has nothing to do with the opening itself. All the rubber bands do is provide neat storage for the lines during packing and deployment. As mentioned above, a pocket or pouch serves the same purpose.

What's important is that they are stowed neatly, and in a way that they will not effect the clean lift of the bag by the PC. If the lines were tight on one side, and loose on the other, it could lead to bag wobble or spin, which can lead to other opening problems. So if you want to 12lbs on each band, that's cool as long as it's 12lbs for all bands. Want zero tension, like a stowless d-bag? That's cool too, it just has to be the same all around.


vanessalh  (D 33301)

Nov 5, 2012, 10:12 AM
Post #12 of 29 (1504 views)
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Re: [JohnSherman] Packing with smaller rubber bands or just double loop? [In reply to] Can't Post

Thanks John,

Out of interest, what is "line dump"?


adamUK  (C 104423)

Nov 5, 2012, 10:17 AM
Post #13 of 29 (1499 views)
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Re: [davelepka] Packing with smaller rubber bands or just double loop? [In reply to] Can't Post

Thanks Dave. That's interesting.

Is there a minimum tension for the mouth locks? I would imagine the mouth locks have to resist the inertial mass of the bag during deployment to make sure the lines reach full stretch before releasing.

Jeez. Been jumping 9 years and I still feel as though I know nowt.


CarpeDiem3  (D License)

Nov 5, 2012, 10:36 AM
Post #14 of 29 (1480 views)
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Re: [vanessalh] Packing with smaller rubber bands or just double loop? [In reply to] Can't Post

In reply to:
I just purchased gear, and am discovering the joys of breaking your own rubber bands. I notice they are typically sold in two sizes (large and small). I can only assume the smaller ones are used for the stows further down the bag.

Never assume anything. Ask your instructors or experienced jumpers before you do it.


(This post was edited by CarpeDiem3 on Nov 5, 2012, 10:37 AM)


pchapman  (D 1014)

Nov 5, 2012, 10:51 AM
Post #15 of 29 (1462 views)
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Re: [CarpeDiem3] Packing with smaller rubber bands or just double loop? [In reply to] Can't Post

In reply to:
In reply to:
I just purchased gear, and am discovering the joys of breaking your own rubber bands. I notice they are typically sold in two sizes (large and small). I can only assume the smaller ones are used for the stows further down the bag.

Never assume anything. Ask your instructors or experienced jumpers before you do it.

That's what he's bloody well doing, asking people here.
"Assume" can be used as part of a question, as a starting point in conversation. Even if he didn't use a question mark on that particular sentence, while doing so on two others.

I assume I've made my point against the "don't assume" cries we often hear on dz.com. (?)


degeneration  (C 106811)

Nov 5, 2012, 10:51 AM
Post #16 of 29 (1459 views)
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Re: [CarpeDiem3] Packing with smaller rubber bands or just double loop? [In reply to] Can't Post

I read/heard/saw/was told once/believe (can't remember which) that double wrapping with larger bands is the way to go as it also helps reduce wear and friction on the lines against the grommets.

On the locking stows, if you only single stow the lines, then the lines are being held on the top by the band, and on the bottom by the grommet. If you have even a slight edge/sharper bit on the grommet, this will wear on your lines as they are rubbing directly on the grommet.

If you double wrap the locking stows, then the lines are being held by the band on the top and the bottom (and sides) and are not in direct contact with the grommet, as the band is between them and the grommet. Therefore if you have a sharper edge or anything on that grommet, it is the band that suffers the extra friction, not your lines. The band will break, and you'll replace it - much cheaper than replacing damaged lines.

So definitely always worth giving your grommets a check for edges etc as well.

I always double wrap all my stows with large bands.


DocPop  (C License)

Nov 5, 2012, 10:55 AM
Post #17 of 29 (1456 views)
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Re: [adamUK] Packing with smaller rubber bands or just double loop? [In reply to] Can't Post

In reply to:
Is there a minimum tension for the mouth locks? I would imagine the mouth locks have to resist the inertial mass of the bag during deployment to make sure the lines reach full stretch before releasing.

That's essentially what the PD boys were telling me.

If the locking stows allow too much stretch, there is the possibility that as the fall rate of the d-bag is slowed by the pilot chute it may partially strip off the canopy until the canopy has slowed down sufficiently. There is, apparently, a danger of disturbing the pack-job during this phase which could lead to a undesirable opening characteristics.

The fear that many people have is that overly tight locking stows can lead to bag-lock. I have heard two well-known John's discuss this:

1. John Sherman (above) points out that Mil. Spec. bands should break before a bag-lock occurs.
2. John LeBlanc has said that a bag-lock requires the prompt execution of Eps, whereas slammer openings have killed people. His preference out of the two is for a bag-lock.


adamUK  (C 104423)

Nov 5, 2012, 11:52 AM
Post #18 of 29 (1427 views)
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Re: [DocPop] Packing with smaller rubber bands or just double loop? [In reply to] Can't Post

In reply to:
1. John Sherman (above) points out that Mil. Spec. bands should break before a bag-lock occurs.
2. John LeBlanc has said that a bag-lock requires the prompt execution of Eps, whereas slammer openings have killed people. His preference out of the two is for a bag-lock.

I watched the PD video on youtube about bag locks which was also informative. I'd certainly avoid the slammer. Holy Sh!t: I'd thought I'd been in a car crash. I'm still not right with my back.


hookitt  (D License)

Nov 5, 2012, 12:46 PM
Post #19 of 29 (1400 views)
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Re: [adamUK] Packing with smaller rubber bands or just double loop? [In reply to] Can't Post

In reply to:
In reply to:
1. John Sherman (above) points out that Mil. Spec. bands should break before a bag-lock occurs.
2. John LeBlanc has said that a bag-lock requires the prompt execution of Eps, whereas slammer openings have killed people. His preference out of the two is for a bag-lock.

I watched the PD video on youtube about bag locks which was also informative. I'd certainly avoid the slammer. Holy Sh!t: I'd thought I'd been in a car crash. I'm still not right with my back.

I would bet you 127 dollars and 50 cents it was not rubber bands. If the slider is allowed to come even a tiny bit before true line stretch, the bottom skin of the canopy will expand rapidly pushing the slider down resulting in pain, seeing stars, or worse.

If the bag stays shut through line stretch, that's all that matters when it comes to line stows. The 2 locking stows won't just fall out and let the bag open. The moment the bridle grabs the bag, the weight of the canopy, essentially pushes against the bags closing flap and causing the canopy to push against the grommets. What does that mean? It means the rubber bands get tighter before the bag leaves your back.

The most common error is not ensuring 100% that the slider is against the stops during, and after you S fold the canopy, then put it into the bag.


(This post was edited by hookitt on Nov 5, 2012, 12:48 PM)


adamUK  (C 104423)

Nov 5, 2012, 12:57 PM
Post #20 of 29 (1386 views)
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Re: [hookitt] Packing with smaller rubber bands or just double loop? [In reply to] Can't Post

In reply to:
I would bet you 127 dollars and 50 cents it was not rubber bands. If the slider is allowed to come even a tiny bit before true line stretch, the bottom skin of the canopy will expand rapidly pushing the slider down resulting in pain, seeing stars, or worse.

If the bag stays shut through line stretch, that's all that matters when it comes to line stows. The 2 locking stows won't just fall out and let the bag open. The moment the bridle grabs the bag, the weight of the canopy, essentially pushes against the bags closing flap and causing the canopy to push against the grommets. What does that mean? It means the rubber bands get tighter before the bag leaves your back.

I think it was the slider but I'd still like to think about the rubber bands. I'd be interested on your views as to what happened in the photo attached (and why!)

Cheers

Adam.

P.S. why $127.50?
Attachments: TandemDeployment.jpg (39.7 KB)


DocPop  (C License)

Nov 5, 2012, 1:31 PM
Post #21 of 29 (1370 views)
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Re: [adamUK] Packing with smaller rubber bands or just double loop? [In reply to] Can't Post

In reply to:
I'd be interested on your views as to what happened in the photo attached (and why!)

Bag strip.

Because the locking stows on the bag failed in some way.


Divalent  (C 40494)

Nov 5, 2012, 1:32 PM
Post #22 of 29 (1369 views)
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Re: [vanessalh] Packing with smaller rubber bands or just double loop? [In reply to] Can't Post

My bag has 3 grommets on the flap, and I use the larger rubber bands double looped to close them. It then also has 2 sets of 3 rubber bands on the sides for stowing additional line (which don't go through grommets) and I use smaller bands just single looped. Once I've stowed through the 3 larger bands, I've gotten below the cascades, so the line bundle thickness a lot less.

visually, the diagram below resembles a view looking down on the top of my D bag, the numbers are stowing bands, in the order I use to stow the lines. 1-3 are large bands double looped, 4-9 are small single looped.

-----2-----1-----3----
4---------------------5
6---------------------7
8---------------------9


(This post was edited by Divalent on Nov 5, 2012, 1:34 PM)


dgw  (C License)

Nov 5, 2012, 1:42 PM
Post #23 of 29 (1357 views)
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Re: [DocPop] Packing with smaller rubber bands or just double loop? [In reply to] Can't Post

In reply to:
In reply to:
Is there a minimum tension for the mouth locks? I would imagine the mouth locks have to resist the inertial mass of the bag during deployment to make sure the lines reach full stretch before releasing.

That's essentially what the PD boys were telling me.

If the locking stows allow too much stretch, there is the possibility that as the fall rate of the d-bag is slowed by the pilot chute it may partially strip off the canopy until the canopy has slowed down sufficiently. There is, apparently, a danger of disturbing the pack-job during this phase which could lead to a undesirable opening characteristics.

The fear that many people have is that overly tight locking stows can lead to bag-lock. I have heard two well-known John's discuss this:

1. John Sherman (above) points out that Mil. Spec. bands should break before a bag-lock occurs.
2. John LeBlanc has said that a bag-lock requires the prompt execution of Eps, whereas slammer openings have killed people. His preference out of the two is for a bag-lock.

The bungees resist not the inertial mass of the bag, but the inertial mass of the lines.


adamUK  (C 104423)

Nov 5, 2012, 2:01 PM
Post #24 of 29 (1352 views)
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Re: [dgw] Packing with smaller rubber bands or just double loop? [In reply to] Can't Post

In reply to:
The bungees resist not the inertial mass of the bag, but the inertial mass of the lines.

I was thinking about the ability of the mouth lock bungees to keep the bag closed at the point it decelerates immediately out of the container. Hence the photo I posted where the bungees had failed.


sundevil777  (D License)

Nov 5, 2012, 4:41 PM
Post #25 of 29 (1304 views)
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Re: [DocPop] Packing with smaller rubber bands or just double loop? [In reply to] Can't Post

In reply to:
In reply to:
I'd be interested on your views as to what happened in the photo attached (and why!)

Bag strip.

Because the locking stows on the bag failed in some way.

That's what you get when you use locking stows that are able to break too easily.

I am a big fan of locking stows that are very resistant to breaking.


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