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pchapman

What manufacturers recommend double wrapping elastics?

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The Safire 3 hard opening thread has ended up having a lot of discussion about line stows.
http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=4884594;

So I want to ask, what do manufacturers actually say about how to stow lines? Which ones recommend double wrapping? Which actually discourage single wrapping? Are they talking about the locking stows, or the other stows in general?

If anyone wants to contribute info, that's great.

Sometimes it is hard to find out what a company thinks, as something might not be in their official manual ... but be in a blog post, video, or whatever.

I'll start with the limited info I have on hand:

-- PD has an old document on hard openings (hrdopn.pdf) dated 2004, that is still on their web site. It doesn't say how to use elastics but gets into the tension issue:

Quote

To check your
stows on the ground, it should take a minimum of 8 pounds,
and ideally 12 pounds of force to unstow the lines pulling the
bag across a smooth surface by the bridle. (The emphasis
should be toward 12 pounds) Use a fish scale on the bridle to
check this. Larger, heavier canopies will require more force,
as does a canopy deployed at higher speeds. (This test is
important to know how well your stow bands will hold your
lines.) You can tighten your stows if they are too loose. If you
use Tube Stoes, look at the instructions that were included
with them. Follow the instructions labeled “For tighter Tube
Stoes”. Rubber bands can be tightened in the same way.
Replace Tube Stoes or rubber bands that appear worn. Do
not wait until they break! The line stows must have between 2
1/2 and 3 inches of line through each stow. Some jumper’s
make shorter stows because they fear baglock malfunctions.
That is not a good idea. Short stows don’t prevent baglocks,
but really do promote line dump. This is because they only
have to slip a little before they are free. Remember, line
dump is potentially more dangerous than a baglock



One can argue about the tension issue since many manufacturers have also been producing semi-stowless bags, where the tension may be relatively low.

That document is also in their "Main User's Manual", which is just a scan of their 1990's printed manual.

-- The current PD manual on "Packing Instructions" says this:

Quote

Follow your container manufacturer’s instructions for closing the bag. Line stow methods vary by container manufacturer.
When using large rubber bands, PD recommends double wrapping all line stows.
For more information regarding line stows, see our video:
http://bit.ly/LockingStowMyth



Their photo shows a Spectra lined canopy, with double wrap stows for regular and locking stows.

Note that it doesn't say "double wrap" -- it says it recommends it if using large rubber bands.

I haven't reviewed the video lately.

-- PD's FAQ section states things a little more emphatically:

Quote

Should I single or double wrap my locking stows?

Double wrap!
It is important to maintain proper tension on all line stows to promote a proper deployment sequence. We have found that this is best accomplished by using large, 2” rubber bands and double wrapping all line stows, including the locking stows. While some may say that double wrapping the locking stows will cause a bag lock, we have seen through thousands of test jumps that this is simply not true.




What do other companies say?

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Aerodyne says this:

"Double stow the center closing stow. "

In the instructions for closing their semi-stowless bag.

https://www.flyaerodyne.com/wp-content/uploads/2017/06/IconManual052017_online.pdf

Also, while some companies dont explicitly recommend one way or another, I noticed the photos in the instruction manual for most rigs show the bag double stowed.

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Westerly

Aerodyne says this:

"Double stow the center closing stow. "

In the instructions for closing their semi-stowless bag.

https://www.flyaerodyne.com/wp-content/uploads/2017/06/IconManual052017_online.pdf

Also, while some companies dont explicitly recommend one way or another, I noticed the photos in the instruction manual for most rigs show the bag double stowed.



Ok, what companies manuals?
Replying to: Re: Stall On Jump Run Emergency Procedure? by billvon

If the plane is unrecoverable then exiting is a very very good idea.

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Mirage, Aerodyne, Rigging Innovations (Curv semi-stowless packing manual) and Sunpath/ Javelin have photos in their manual showing bags with double wrapped stows. It's a bit hard to tell, but it appears that the photos in UTP's user manual show the bag as double wrapped on the locking stows as well. Icarus does not mention double stowing in their manual that I can see, but I found at least one Icarus related reference that claims they recommend double stowing here:

https://parachutistonline.com/safety_training/ask_a_rigger/double-wrap-stow-bands

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I got the link wrong. Here it is:

https://web.archive.org/web/20160329231946/https://parachutistonline.com/safety_training/ask_a_rigger/double-wrap-stow-bands



Regarding the Javelin, here is the current manual:

https://www.sunpath.com/_docs/manual/spp_manual_print_rev1.pdf


Page 80, Fig 114 shows double wrapped line stows. I cant tell if the locking stows are single or double wrapped, but the line stows are double wrapped.

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Because he was packing the line stows with of the use of medium bands. If you read that whole article from parachutist, packers didn't like dealing with micro bands and double stowing can cause line twist when they get the bag spinning. I've had some very hard openings using double stows and and some pretty serious line twist. PD said I wasn't packing my Sabre1 170 correctly. Turns out I wasn't alone. Single wrapped medium band locking stows and and micro bands for the line stows has been working really well for me.
Replying to: Re: Stall On Jump Run Emergency Procedure? by billvon

If the plane is unrecoverable then exiting is a very very good idea.

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DBCOOPER

Because he was packing the line stows with of the use of medium bands. If you read that whole article from parachutist, packers didn't like dealing with micro bands and double stowing can cause line twist when they get the bag spinning. I've had some very hard openings using double stows and and some pretty serious line twist. PD said I wasn't packing my Sabre1 170 correctly. Turns out I wasn't alone. Single wrapped medium band locking stows and and micro bands for the line stows has been working really well for me.



Can you please clarify what you mean by 'medium' and 'micro' bands?

I'm used to 3 sizes.

Small - approx 3/4" diameter, 3/8" wide.

Large - approx 1 3/8" diameter, 3/8" wide.

Tandem - Same diameter as "large", but 3/4" wide.

I generally use large (double wrapped) on the locking stows, and small (single wrapped) on the rest.
"There are NO situations which do not call for a French Maid outfit." Lucky McSwervy

"~ya don't GET old by being weak & stupid!" - Airtwardo

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From the Parachutist story referenced above

Getting here is a journey that started with everyone wrapping each bight of lines with the common 3/8-inch-wide by 2-inch-diameter by 1/16-inch-thick (10mm x 50mm x 1.6mm) natural rubber bands available from most equipment dealers. These medium bands seemed to work fine, but back then, lines were fatter, more elastic and more numerous.

I just call them large and small myself.



As lines became smaller and made of new materials that don’t stretch to absorb much opening shock, people began double wrapping their stow bands to prevent the bights from coming out too early in the deployment sequence. Many experts warned against the double wrap, saying it caused knots, line twists and possibly bag locks. Smaller “micro-line bands” the same width and thickness but only 1½ inch or 1¼ inch (38 or 32mm) in diameter came into existence. Also came the pricier, longer-lasting Tube Stoes (designed like a snake eating its tail) in several sizes, which some jumpers still prefer.
Replying to: Re: Stall On Jump Run Emergency Procedure? by billvon

If the plane is unrecoverable then exiting is a very very good idea.

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Those 3/4” wide tandem rubber bands are exclusive to Vector Tandems with thick, Dacron suspension lines. They solve a problem created by heavy Dacron lines dumping prematurely. In the worst scenario, the drogue jerks the d-bag out of the container, but leaves all the lines in the container, creating a “spaghetti mess!” In the evening worst scenario, the slider remains in the container as the canopy fabric inflates!

All the different tandem manufacturers have suffered line dump and they have all developed a variety of solutions. Strong added an Anti Line Slump Flap to their d-bags. Parachutes de France and Eclipse added extra locking stows while Racer developed their Speed-Bag where every line stow is a locking stow. RWS/UPT developed double-wide rubber bands for civilian tandems and triple-wide rubber bands for military tandems. Hint: military tandems like to start with barrels containing 500 pounds of cargo!

Line weight seems to be the deciding factor because when you pack Icarus mains - with slender lines (HMA or Vectran) they open just fine with MIL SPEC standard-sized rubber bands.

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pchapman



One can argue about the tension issue since many manufacturers have also been producing semi-stowless bags, where the tension may be relatively low.


About the SS-Dbags
As stated, the ideal situation for a favorable opening is that the lines come to full stretch prior to the canopy exiting the bag. If the locking stows are tightly double wrapped on a semi-stowless bag this is almost sure to happen. The lines will very likely come to full stretch prior to unlocking the bag and exposing the canopy. This is what the goal is.
Personally I jump a wings SS-Dbag with HMA700 lines, 4 double wrapped locking stows on a sabre2. My openings are fu%king awesome.

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To add some datapoints to the mix:

1. Variance of release force is much greater with double stows than with single stows. Meaning off headings and line twists are much more likely
2. After I switched to single stowing small rubber bands opening heading performance increased.
3. I have about 200 jumps on a wings semi stowless d bag single stowing bungees (comes like that from manufacturer... release force - less than a pound). It worked beautifully.

Like someone mentioned in this thread, the purpose of the stows is to keep your bag locked until line stretch. Single stows are more than capable of doing that.

Everyone is a big boy and can decide for themselves how to pack their stuff. But I've gotten better performance out of single stowing small rubber bands, so I'm gonna stick to doing just that.

If you have shitty openings, ask one of the more experienced people than you for some advice.

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Quote

If you have shitty openings, ask one of the more experienced people than you for some advice.



Or go with what most of the major manufacturers have been saying for years. Which pretty much happens to be the opposite of what you just posted.

Quote

Everyone is a big boy and can decide for themselves how to pack their stuff.



Well....that part is true.

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lyosha

To add some datapoints to the mix:

1. Variance of release force is much greater with double stows than with single stows. Meaning off headings and line twists are much more likely
2. After I switched to single stowing small rubber bands opening heading performance increased.
3. I have about 200 jumps on a wings semi stowless d bag single stowing bungees (comes like that from manufacturer... release force - less than a pound). It worked beautifully.

Like someone mentioned in this thread, the purpose of the stows is to keep your bag locked until line stretch. Single stows are more than capable of doing that.

Everyone is a big boy and can decide for themselves how to pack their stuff. But I've gotten better performance out of single stowing small rubber bands, so I'm gonna stick to doing just that.

If you have shitty openings, ask one of the more experienced people than you for some advice.



lyosha



Like someone mentioned in this thread, the purpose of the stows is to keep your bag locked until line stretch. Single stows are more than capable of doing that.

If you're using small bands and they provide adequate stow tension. But often times they dont because people use the large bands and the lines basically just fall out.

There are videos on YouTube showing what happens when the locking stows come off early. The results are very serious and can be lethal. People have died from hard openings and I've met more than one person who broke their neck or suffered some other form of serious injury from a hard opening.

Here is a video of what happens when the locking stows come off too early (bag strip):

https://www.youtube.com/watch?v=wdR47kcMRz8


http://www.dropzone.com/cgi-bin/forum/gforum.cgi?do=post_attachment;postatt_id=134145;t=search_engine

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