Opinions on tube-stows

[SkydiveMonkey 0]

Ok, I've just put tube stows on my d-bag (all tubestows, no bungies). Is this a good idea? I don't want to mess about with bungies all the time, but would welcome opinions on this. I know some people have tube stows just on the locking stows.
When you participate in sporting events, its not whether you win or you're loose, its how drunk you get.

[dove 0]

Uh-oh! Boy did you ask for it! Some people have opinions about tube stoes as strong as their opinions about AADs and RSLs! Personally, I LOVE tube stoes. I have had nothing but beautiful openings and they don't chew up my dainty girl hands. (Hehehe - yeah, right!) And it is nice not to have to go hunting around for a new rubber band after every jump. Just make sure you use the proper locking stoes and not the smaller ones for locking.
dove

[skymedic 0]

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and they don't chew up my dainty girl hands.

can I take a closer look at those "girl hands"...LOL.....
Cheers....vasbyt
marc
"I have no fear of falling, I just hate hitting the ground"-The Badlees...

[Jessica 0]

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...and they don't chew up my dainty girl hands.

That's exactly why I like them. Rubber bands hurt.
The door is open
We are way the fuck up here
Might as well get out.
~ FallingMarc

[SkydiveMonkey 0]

Yeah, I made sure to use the 2 larger ones for the locking stows. I know people have a lot of opinions on these, I'm asking to find them out When you participate in sporting events, its not whether you win or you're loose, its how drunk you get.

[skymedic 0]

I know SkymonkeyOne uses em...and loves em..ask him...or I am sure he will chime in..
Me? I am a rubber band jumper....nothing against tube stoes...there just not for me....
Cheers....vasbyt
marc
"I have no fear of falling, I just hate hitting the ground"-The Badlees...

[Zennie 0]

Do tube stows break?
(This is a loaded question )
"Zero Tolerance: the politically correct term for zero thought, zero common sense."

[PhreeZone 20]

Zennie... yes they do, but at a higher level then bands. Personally I use SkyStoes for as many things as possible but after packing a rig with Tube stoes all weekend and week, I have to admit that they are just fine and last a long time.

[Zennie 0]

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yes they do, but at a higher level then bands

A much higher level.
The words "bag lock" come to mind.
"Zero Tolerance: the politically correct term for zero thought, zero common sense."

[SkydiveMonkey 0]

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bag lock

2 words - reserve canopy
When you participate in sporting events, its not whether you win or you're loose, its how drunk you get.

[skymedic 0]

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The words "bag lock" come to mind

this can happen on rubber banded rigs too...I kinda think this is more skydiving folk lore than true scientific fact.....
Cheers....vasbyt
marc
"I have no fear of falling, I just hate hitting the ground"-The Badlees...

[Zennie 0]

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this can happen on rubber banded rigs too...I kinda think this is more skydiving folk lore than true scientific fact.....

Rubber bands are designed to break. Tube stows are not.
It would be interesing to do a stress test and see how many pounds of force it takes to break a tube stow as opposed to a military grade rubber band.
In the meantime, I'm sticking with rubber bands. They're not that difficult to replace.
"Zero Tolerance: the politically correct term for zero thought, zero common sense."

[Zennie 0]

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reserve canopy

I see your two, and raise you two more words, "reserve repack".
"Zero Tolerance: the politically correct term for zero thought, zero common sense."

[SkydiveMonkey 0]

I'll see that, and throw in another two - beer case When you participate in sporting events, its not whether you win or you're loose, its how drunk you get.

[polarbear 1]

I was just saying in another thread that I have found that out of all the stow bands, I have found it the hardest to get tight line stows with tube stows (yes I know how to tighten them). I use rubber bands; they work the best for me. Check out the thread entitled "Line Dump" in the safety and training forum.
Bottom line is if tube stows work for you, then they work for you. Many people use them with success.

[polarbear 1]

I'll see that and raise
"Bottle of favorite liquor for rigger who saved your ass"
and
"Cutaway, baglocked main is hard to find in a corn field"

[Hooknswoop 19]

2000+ jumps on tube stows, no line dump, no bag locks, no problems. I have to replace a broken tube stow about once every 100 jumps. Saves a lot of time packing. If line dump was such a big problem, it would happen to reserves all the time. It doesn't. People say that tube tows cause bag locks (don't break and hold the line too tight) and they say that tube stows cause line dump (don't hold the lines at all, too loose.) Which is it? They can't be both.
As long as the locking stows hold (which doesn't take all that much) you won't have line dump, regardless of what the rest of the lines do. If the locking stows are 4 1/2 inches apart, and you make 1 1/2 inch locking stows, you have 6 inches of line outside the stows and 4 1/2 inches of line between the locking stows. With more line outside the stows, the lines wouldn't fall out of the stows, regardless of how loose they are. I don't recommend loose stows, but I also don't believe that line dump happens nearly as often as is claimed.
Hook

[skybytch 273]

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People say that tube tows cause bag locks (don't break and hold the line too tight) and they say that tube stows cause line dump (don't hold the lines at all, too loose.) Which is it? They can't be both.

I agree. Can anyone give specific examples of a bag lock caused directly by tube stoes? I've never seen it. Line dump is harder to prove, but does anyone have a personal experience with tube stoes causing line dump?
pull & flare,
lisa
[subliminal msg]My website Go Now[/subliminal msg]

[polarbear 1]

First off, as I said in my previous post, I know that many, many people have used tube stows with success.
Second, my opinions are based on experiments I did on the ground. I used different stow bands and tightened them until I got the PD-recommended 8-12 pounds of force necessary to unstow the lines.
With tube stows, I found that even when they were very tight, they still had a tendency to roll off very easily due to their round profile. Flat band shaped stows have to flip; they seem to get a better grip. It was easiest for me to get the 8-12 ponds with bands. I used to use tube stows because they lasted longer, but frankly, I have since gotten better openings with bands. It works for me, I have no desire to change.
As far as baglocks go, there is more than one way for this to occur. One is that the band is so tight the lines can't come out. I HAVE NEVER SEEN THIS WITH ANY STOW BAND. In this instance, a band made of latex will be harder to break then a gum rubber band.
Two is that a loop of line from one stow goes over a neighboring stow...this is the most common explanation for a baglock I have heard. In this case, it may be the case that a breaking band won't help. It may also be the case that if a band breaks, it will help...it just depends on the geometery. It is possible that a band may not hold the lines very tightly, but unless it breaks, a bag lock will occur. Again, it just depends on geometry.
Three is that the band is tight enough that on a closing stow, the lines are sucked into the grommet, preventing them from unstowing. I have heard of this happening. In this case, the band will have to break if the lines are going to unstow. As previousy mentioned, because of the rolling phenomenon, I have found tube stows have to be tighter to provide 8-12 pounds, thus they are more likely to pull lines into the grommet. Since they are made of latex, they are harder to break.
Now after having said all of that, I will reiterate what I have already said many other times in this and other threads. USE WHAT WORKS FOR YOU. If tube stows work, fine. I have better luck with rubber bands so I use them.

[polarbear 1]

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If line dump was such a big problem, it would happen to reserves all the time.

How do you figure?

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As long as the locking stows hold (which doesn't take all that much) you won't have line dump

As long as the locking stows hold, you won't have CANOPY DUMP. The rest of the lines can still dump. If all of your lines are stowed tightly, it requires more force to unstow them. As the lines unstow, this higher unstowing force keeps the bag from slowing down as much. When you reach line extension, you suddenly accelerate the canopy+bag+pilot chute to your freefall velocity-this is called snatch force and is the first force you feel during opening. A bigger difference in velocity between you and the bag+canopy+pilot chute creates a higher snatch force. Thus, if the bag slows down less, the snatch force is lower.
Also, the snatch force is input to the canopy through the lines at the bottom and the bridle at the top...thus it "racks" the pack job, which can help to disorganize it. A more disorganized canopy has the potential to inflate violently/unevenly.
When I actually tightened my stows (all of them) to the point of needing 8-12 pounds of unstowing force, my openings (and particularly the snatch force) got much lower. I have accomplished this on two completly different parachute systems. Another jumper at my DZ was jumping a brand new Velocity 90 that was seriously spanking him on opening. He had one so hard he actually ruptured his lymph glands and hurt his neck. After tightening his bands the way I do, he gets smooth openings EVERY time.

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I also don't believe that line dump happens nearly as often as is claimed.

I disagree. I think it happens more than people realize. Almost every time I pack a rig, I find it has very loose line stows. After tightening them, I have on several occasions had people tell me "that was a softer opening than I am accustomed to". I would agree that canopy dump probably doesn't occur with high frequency.
Now, I will reiterate for the final time, USE WHAT WORKS. If you are happy with your openings, than that's it. If your openings are hard, I have found that it is almost always one of two things 1)the slider isn't in the right place 2)the lines are stowed too loose.

[pilotdave 0]

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Can anyone give specific examples of a bag lock caused directly by tube stoes?

This isn't much help because I don't know any details, but a guy at my DZ had a baglock last year. Weeks later they found his main, still in the bag. According to the rigger that told me about it, it was caused by a tubestow that didn't break when a rubber band would have. If anyone is really curious about what happened I guess I could give ya his email address. I've never seen anyone using tubestoes so I don't know anything about them, but I'm staying away from them.
By the way, anyone bought rubber bands from square3 at cross keys? I bought a bag of the little ones and they break REALLY easily. I've broken a few just pulling them tight when I'm replacing a broken one. Replacing them often is annoying but it seems to me that being too easy to break is better than being to hard to break.
Dave
http://www.skydivingmovies.com

[kmcguffee 0]

Can you explain how you 'tighten' your stows? I can think of a few ways but I would like to know how you are doing it. I don't think anyone at my DZ does it. We just use different sized rubber bands to get different amounts of unstowing force.

[polarbear 1]

It is hard to explain over the internet...the instructions in a package of tube stows shows how to do it. Basically, you are using the same larks head knot you normally would, but are looping the free end through more than once.

[Hooknswoop 19]

OK, So I was driving out to the DZ thinking about PC, stows, and openings. What if tighter stows slow the jumper down, giving softer openings? The pilot chute pulls on one side of the bag, and your weight pulls on the other, so the tighter the stows, the more the force of the pilot chute slows down the jumper. So with really tight stows and a big pilot chute, the openings should be really soft. With a small pilot chute and not as tight stows, not much force is apllied to the jumper to slow them down for deployment. Of course the pilot chute is pulling on the risers throught the d-bag, stows and lines, standing the jumper up. Would the jumpers speed increase? OK I am confused. Too many variables
I do think snatch force is based on fall rate and canopy/slider size more than anything else. The initial opening force on my VX-60 w/ a very small slider and canopy, is noticably less than on my Safire 189 w/ a big canopy and a huge slider.
This is a cool thread. It has really got me thinking.
Hook

[polarbear 1]

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OK, So I was driving out to the DZ thinking about PC, stows, and openings. What if tighter stows slow the jumper down, giving softer openings? The pilot chute pulls on one side of the bag, and your weight pulls on the other, so the tighter the stows, the more the force of the pilot chute slows down the jumper. So with really tight stows and a big pilot chute, the openings should be really soft. With a small pilot chute and not as tight stows, not much force is apllied to the jumper to slow them down for deployment.

I don't think tighter stows can really slow a jumper down much. Really tight line stows would require maybe 10 pounds to unstow them; this 10 pounds is the force transmitted to the jumper. 10 pounds of unstowing force in the "up" direction isn't much to the 200 lbs (average) in the "down" direction that the jumper weighs.
10 lbs is significant to the weight of the bag+canopy+ pilot chute, and a figure I heard for pilot chute drag at terminal is ~70 lbs. 10 lbs. is a much higher percentage of 70lbs. then 200 lbs.
Now, smaller pilot chutes typically have less drag, meaning they accelerate the bag away from the jumper less. They don't really affect the jumper at all...no matter what drag force the pilot chute produces, the jumper only feels the force required to unstow the lines, which is the same no matter what the pilot chute drag. If the bag is accelerated less by a smaller pilot chute, there will be a smaller velocity difference between the bag+canopy+pilot chute and the jumper at line extension.
The exception is that a too-high drag pilot chute will cause line dump, which means there will be no unstowing force at all on either the bag or jumper.

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Of course the pilot chute is pulling on the risers throught the d-bag, stows and lines, standing the jumper up. Would the jumpers speed increase? OK I am confused. Too many variables

It does tend to stand the jumper up, but it happens so fast there is no time for the jumper to accelerate to a higher freefal speed.

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I do think snatch force is based on fall rate and canopy/slider size more than anything else. The initial opening force on my VX-60 w/ a very small slider and canopy, is noticably less than on my Safire 189 w/ a big canopy and a huge slider.

As it turns out, snatch force is defined as I said earlier...when the mass of the bag+(uninflated) canopy + pilot chute is suddenly accelerated to the jumper's freefall speed. Once this occurs, snatch force is done. Inflation force takes over. Now is where my (presumed)understanding of it all starts getting foggy. What I think happens is (in a normal opening) the bottom skin of the center cells (and maybe the center cells themselves) and the slider inflate, which starts the inflation force. If the center cells haven't inflated yet, they then do so. At this point the center of the canopy has its airfoil shape and begins flying forward (albeit very slowly). It is still descending fast.
The primary inflation force slows the jumper down, which lessens the force holding the slider up. Air pressure through the crossports and at the nose of the canopy starts to inflate the cells adjacent to the center cells. The spanwise inflation forces overcome the slider forces and push the slider down, alowing the canopy to spread and fully inflate. On my old heatwave, the right end cell does not inflate and the canopy begins to turn to the right, making polarbear grab his rear risers and flare, while hoping his tracking was good enough to get away from everyone.
The primary inflation force (I think) depends mostly on the area of the slider and the area of canopy first exposed to the airstream. I don't really know. Inflation forces are mainly a function of airspeed and canopy design. The rest of the inflation has to do with how slowly it takes the canopy to spread and the slider to come down. I would appreciate some knowledgeable canopy designer (cobaltdan? brian germain?) explaining the rest of it.