Double stowing suspension lines

[smiler 0]

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Too tight of stows and you will get a bag lock.

I really don't get this. The whole point of bungees is that they stretch, and once they can't stretch any more, they break. I'm not talking about tube stows here. How could a pilot chute in decent condition (or even an old one!) not exert enough force on a bungee to stretch it enough to release the lines, or break it? And you're talking about a drogue, not just a pilot chute!

No matter how you release the lines on the ground, the theory that tight stows can cause a bag lock can only be true if you are putting 100-150 lbs of force on the bag and they're still not coming off?

www.wingin-it.co.uk
Wingin' It wingsuit school

[Hooknswoop 19]

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How could a pilot chute in decent condition (or even an old one!) not exert enough force on a bungee to stretch it enough to release the lines, or break it? And you're talking about a drogue, not just a pilot chute!

Yep, strange but true. You wouldn't think a rubber band would be able to hold, but they cn, especially when the bag tilts because it is pull from a band and the edge of the bag and pulling on the next band too. Bag locks happen. If rubber bands always broke, there wouldn't be bag locks with rubber-band equipped d-bags. But there is.

Derek

[mdrejhon 8]

I just started jumping my packjobs (first packjob last weekend, jumped 5).

Several of the small rubberbands on my D-bag broke, so I had to use the dropzone's larger bands. They were too loose (slack) on the bottom of the lines, so I had to double-wrap.

I also now have the bigger bands on the two locking stows after the small bands on those broke too (I hope I got the terminology correct -- these are the first two stows after the lines comes out of the D-bag?).

I have had 1 soft opening, 3 normal openings, and 1 relatively hard opening. (Sabre 170, known for hard openings) About statistically the same as the other packers.

Now this post got me thinking. The softest opening was when I had the small rubber bands on the locking stows.

I am going to inquire at the dropzone on the next visit. Maybe I should be buying my own rubber bands rather than using the dropzone supplied.

[Hooknswoop 19]

Ue the smaller bands. For openings, control the lines and make sure to keep all 4 slider gromments against the stops (washers in the stabilizers).

Derek

[rigger_john 0]

I've seen quite a few bag locks in my 15 years of rigging and almost every one I've ever seen has been because of asymmetrical line deployment. This results in a set of lines from one riser dragging against the closed flap of the d-bag and the line group that remains stowed is not subject to any pressure from the pilot chute. The bands don't fail to break because they are to strong. They don't break because there is no pressure excerted on them.

Another way for a bag lock to occur is if a loop of stowed line from one band manages to loop over a portion of lines in another stow. In this case the band will not break because again the pressure from the pilot chute is either against the tape on that the band is looped onto or because the line has a leaverage advantage against the pilot chute.

In either case double stowing is irrelevant. the bands would break if there was pressure on them.

I repeat Smilers question. Does anybody have ANY direct evidence of double stowing causing a mal. Just because the bag didn't open does not mean the bands were to strong I have seen a baglock on a bag that had single stow with quite weak bands.

I hear a lot of anecdotal evidence but nobody has given a single case where double stowing caused a mal beyoned any doubt.

_________________________________________

Nullius in Verba

[bluewaterstream 0]

Double stowing has never caused a mal that I had to cut away from, but double stowing did seem to cause my deployments to take longer to achieve line stretch, caused off heading openings, and occasional line twists. Changing to single stows using smaller bands on the non-lockers has solved all of these deployment issues for me. This change has improved my openings dramatically and I have had faster, on-heading openings ever since.

Now I single stow everything: large bands (always tight) on my locking stows and small bands (not so tight) on everything else. I view my small band single stows as an organized alternative method to free stowing; these stows, IMO, do not need to be as tight as the locking stows do, but the lines still should be organized and held in place tight enough to prevent an out of sequence deployment.

Take a look at the line management of your reserve - a few locking stows and the rest of the lines are free stowed in an organized manner, they are not and do not need to be tightly secured with single or double stows.

John

[brettpobastad 0]

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Bag locks happen. If rubber bands always broke, there wouldn't be bag locks with rubber-band equipped d-bags. But there is.

Incorrect. A rubber band, even if you 'quadruple stow', will not directly cause a bag lock. The rubber band WILL break. Bag locks are caused by sloppy packing and incompatible equipment components

"It's only arrogance if you can't back it up"

[Hooknswoop 19]

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I hear a lot of anecdotal evidence but nobody has given a single case where double stowing caused a mal beyoned any doubt.

The bag lock on the tandem was without a doubt caused by double stowing. I saw it in the air and confirmed it on the ground.

Derek

[Hooknswoop 19]

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A rubber band, even if you 'quadruple stow', will not directly cause a bag lock. The rubber band WILL break. Bag locks are caused by sloppy packing and incompatible equipment components

Incorrect, it happened to me.

Derek

[brettpobastad 0]

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The bag lock on the tandem was without a doubt caused by double stowing. I saw it in the air and confirmed it on the ground.

What system was it?

"It's only arrogance if you can't back it up"

[brettpobastad 0]

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The bag lock on the tandem was without a doubt caused by double stowing. I saw it in the air and confirmed it on the ground.

What kind of stows? Long? Short? What kind of stow bands? Rubber bands? Tube Stoes? Bungee Elastic? Those red or black Butyl rubber deals?

Got any pictures?

"It's only arrogance if you can't back it up"

[brettpobastad 0]

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I hear a lot of anecdotal evidence but nobody has given a single case where double stowing caused a mal beyoned any doubt.

I agree.

In order of importance when stowing canopy suspension lines:

1. NEAT stows.
2. EVEN stows.
3. LONG stows.

And a distant….
4. SNUG stows

When stowing your lines, it is most critical to be neat. Sloppy line stows will only enhance the ngative effects of everything else. It is also important to make all the stows the same length and tension. Longer stows work better than shorter ones. I feel that two to three inches works the best. Jumpers double stow suspension lines to avoid line dump or to soften openings by slowing down line deployment. A better way to avoid line dump is to lengthen your stows and be neat about it. Double stowing your lines can actually increase the overall deployment force of your parachute system. Double stowing also contributes to line twists and ‘off heading’ openings.

Use the right size rubber bands for the job. I find that regular rubber bands work the best for the first one or two locking stows (depending on D-bag configuration) with most all line types. Mini rubber bands after that for micro-lines, etc. and regular rubber bands for Dacron. I would avoid any other type of stow bands.

I would avoid surgical tubing style bands as well as those red and black Butyl rubber things.

"It's only arrogance if you can't back it up"

[Hooknswoop 19]

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What kind of stows? Long? Short?

Not long, not short, 3 inches +/-.

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What kind of stow bands? Rubber bands? Tube Stoes? Bungee Elastic? Those red or black Butyl rubber deals?

Plain old large rubber bands.

Derek

[nate_1979 9]

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In order of importance when stowing canopy suspension lines:

1. NEAT stows.
2. EVEN stows.
3. LONG stows.

And a distant….
4. SNUG stows

I used to use longer stows on my rig, until a few jumps ago when someone told me that if I have longer stows I am risking a bag lock, so I have changed my stows to small ones... The reasoning given to me made sense, the larger your stows the bigger the chance that lines from a later deployed stow could get caught in the loop of an earlier deployed stow, which would effectively stop the deployment process. (sorry if that doesnt make a ton of sense, I dont know how else ot explain it )

FGF #???
I miss the sky...
There are 10 types of people in the world... those who understand binary and those who don't.

[brettpobastad 0]

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someone told me that if I have longer stows I am risking a bag lock

Let me ask you a couple of questions:

Who was that 'someone'?

Did he elaborate and show you how and why that might happen?

Did he have any specific examples?

And more importantly, where you having any sort of deployment problems at the time?

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The reasoning given to me made sense, the larger your stows the bigger the chance that lines from a later deployed stow could get caught in the loop of an earlier deployed stow

I'm thinking you must mean that as the lines unstow, the could wrap around other stows that are too long??

"It's only arrogance if you can't back it up"

[Hooknswoop 19]

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What system was it?

Vector Tandem

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Got any pictures?

No, I didn't have a camera at the DZ.

Plain old large rubber bands double wrapped caused a bag lock on a Vector Tandem system. When I looked over my shoulder because of the abnormally long trap door, the bag was about 8-10 feet above me, with 4 stows still stowed, the lines were even, all going straight to one stow. On the ground, pulling on the lines with my foot on the bridle, the stows refused to unstow.

So, there you have it, a true-to-life case of double wrapping rubber bands causing a bag lock on a tandem.

Derek

[brettpobastad 0]

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I firmly believe that tight rubber bands can prevent all sorts of nasty out-of-sequence deployments

Gotta disagree, RR. Tight stows may artificially mask other issues such as sloppy or short line stows, or mismatched or improper components. In other words, a triple stowed mini rubber band might keep a short, sloppy stow from releasing out of order, but that's the wrong way to address the problem and by doing that, you may be creating a whole bunch of other issues.

Check out 8.1.12 of the Poindexter Manual.

Brett

"It's only arrogance if you can't back it up"

[mjosparky 4]

There 2 thing that affect how hard a canopy opens, the slider and the fill time. For the slider it is the size, shape and placement during packing. The fill time is a function of design and can be controlled to some extent by how the nose is handled during packing. Anything that happens before the canopy comes out of the bag does not affect opening shock because the canopy is not opening if it is still in the bag. As I mentioned in another thread, I have over 1000 jumps on a bag that uses just 2 locking stows. The rest of the lines are stowed in a side pocket for the purpose of order only. I can pack the canopy to knock your socks off or to give you a 500 foot snivel.

Those who think they get better, on heading openings from not double stowing or not using tight stows, the reason is because the bag is not whipping back and forth as much which causes asymmetrical and off heading openings. But it has nothing to do with how hard the canopy opens.

Sparky

My idea of a fair fight is clubbing baby seals

[nate_1979 9]

That "someone" was one of the senior packers at my DZ.. Yes, he did elaborate and showed me exactly how a baglock could occur, he stopped and showed me on the pack job that I had just bagged and stowed the lines on as I was about to put it into my container. I have had some interesting openings, but none of them have been baglock. And what I ment is that , how to put it, ... You have your stows which hold the bag shut, then I have 3 rows of stows below that on the bag, I'll number them rows 1 through 3, 1 being the closest to the stows which hold the bag shut.. Basicly, if Stow 1 has a large amount of line on the outer side of the rubber band, then the lines from stow 1 could get caught in the loop created by the excess line on stow 2, when it came time to deploy stow 2 would tighten around the lines of stow 1 and possibly prevent the deployment sequence from continuing. I can definately see how this could happen, .. clearly your not going to have those lines mixed like that, but I could see the lines just mixing, say, when your closing the container... It's just a possibility, far fetched mabey, but one I'd prefer to prevent.

Another aspect too is that I've noticed the lines on my canopy definately get caught with eachother more so than other types of lines (my canopy is HMA), so I think from my limited knowledge that the capability of my lines grabbing eachother and holding are a big higher than some types of lines that might just pull apart, but I could be wrong.

I also asked my rigger about this, and he confirmed with me that I should not have alot of line in my stows.

As far as deployment since I started putting less line in my stows, I have noticed that it happens a bit faster than it used to, but people have told me that doesnt make much sense either, .. but I dunno .. I'm thinking that my time for line stretch might be shorter, mabey feeling a bit more on the initial opening jerk?

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someone told me that if I have longer stows I am risking a bag lock

Let me ask you a couple of questions:

Who was that 'someone'?

Did he elaborate and show you how and why that might happen?

Did he have any specific examples?

And more importantly, where you having any sort of deployment problems at the time?

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The reasoning given to me made sense, the larger your stows the bigger the chance that lines from a later deployed stow could get caught in the loop of an earlier deployed stow

I'm thinking you must mean that as the lines unstow, the could wrap around other stows that are too long??

FGF #???
I miss the sky...
There are 10 types of people in the world... those who understand binary and those who don't.

[brettpobastad 0]

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Anything that happens before the canopy comes out of the bag does not affect opening shock

Technically true. Opening shock is opening shock. that's a function of the canopy and slider. It can be affected (for better or worse) by such things as slider placement and how you treat the leading edge, etc.

However.....Snatch force is affected (again, for better or worse) by how you stow the lines (as well as pilot chute type and size, bridle length, d-bag type, etc.) If you decrease snatch force too much (by double stowing, for example) you may actually increase the forthcoming opening shock.

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There 2 thing that affect how hard a canopy opens, the slider and the fill time.

This statement is also correct. but there are a whole hellava lot more things that affect how 'hard' or how 'soft' your parachute opens besides just the size of the slider and how fast air goes in the nose. My experience tells me that it is much easier to fuck up a properly folded canopy with improperly stowed lines than the reverse. An example in plain english would be that a properly quartered slider and rolling the shit outta the nose won't make a bit of difference if you double stow your lines and your using a worn-out 21 inch pilot chute.

The point of this whole excersize is not that double stowing your lines is bad (it is!) The point is that most jumpers don't understand the dynamics of an opening parachute.

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Those who think they get better, on heading openings from not double stowing or not using tight stows

I'll be honest, I don't quite understand what you are trying to say here so I'll respond by saying...

"If you double stow your suspension lines, you can expect an increase in line twists and off-heading openings. This phenomenom occurs because the stows are now too tight, compromising the oreintation of the bagged canopy as the jumper continues to accelerate away from it (the d-bag will 'dance around' and 'ossilate')"

I think that's what you are trying to say here:

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Those who think they get better, on heading openings from not double stowing or not using tight stows, the reason is because the bag is not whipping back and forth as much which causes asymmetrical and off heading openings.

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But it has nothing to do with how hard the canopy opens.

Not true. It has a whole lot to do with how hard or how soft your parachute opens. Jumpers think (correctly) that if they double stow their lines they will slow down that part of the opening process. What many do not understand is that if you slow down this part of the process too much, the bagged canopy now has time to catch up to the speed of the jumper, thus resulting in more 'opening shock' because that faster moving mass of nylon will fill up with are faster and hammer your fat ass! (sorry, got a bit carried away there for a sec) You can see how a pilot chute that is worn out or too small would make it worse. You can see how tight jumpsuits faster freefall speeds might also affect openings.

Some also believe that double stowing will prevent line dump. Maybe, but the inherent drawbacks could be far worse. There are better ways (neat, even long stows) to do that.

Use your rubber bands for 'good' not evil! Don't double stow!

"It's only arrogance if you can't back it up"

[brettpobastad 0]

What is a 'Senior Packer'?

"It's only arrogance if you can't back it up"

[rigger_john 0]

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Take a look at the line management of your reserve - a few locking stows and the rest of the lines are free stowed in an organized manner, they are not and do not need to be tightly secured with single or double stows.

I think the line management on a reserve is a side issue here. We use a line stow pocket on free bags because when you are at 750 feet doing 120 mph line dump is a lesser evil than line hesitation.

_________________________________________

Nullius in Verba

[rigger_john 0]

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***
So, there you have it, a true-to-life case of double wrapping rubber bands causing a bag lock on a tandem.

Derek

When you pulled on the bag the bands neither unstowed or broke? Is the canopy still stuck in the bag or did you manage to get it out.

I'm not sure how much force a tandem drogue puts on a stow band but I be very very surprised if it wasn't enough to break a rubber band double stowed or not. I suspect that other factors were involed.

_________________________________________

Nullius in Verba

[riggerrob 643]

Plain old large rubber bands double wrapped caused a bag lock on a Vector Tandem system.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

There is your problem.
Regular rubber bands are incompatible with the bulky Dacron lines on Vector tandem canopies.
Relative Workshop recommends double-wide rubber bands on their (tandem) main d-bags.

Any time you ignore manufacturers' instructions you become a test-jumper.

[riggerrob 643]

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I firmly believe that tight rubber bands can prevent all sorts of nasty out-of-sequence deployments

Gotta disagree, RR. Tight stows may artificially mask other issues such as sloppy or short line stows, or mismatched or improper components. In other words, a triple stowed mini rubber band might keep a short, sloppy stow from releasing out of order, but that's the wrong way to address the problem and by doing that, you may be creating a whole bunch of other issues.

Check out 8.1.12 of the Poindexter Manual.

Brett

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Strangley, we agree on this issue.

I was trying to say that if all your line stows are sloppy, mis-matched rubber bands, etc .... double wrapping the last few stows (close to risers) will mask a variety of sins.
It is called erring on the side of caution.