2-Stow Bag

[KellyF 16]

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I have heard of bag strip and have asked several times if anyone, anywhere, in all the thousands and thousands of canopy deployments of video, for video of bag strip. No one has ever shown video of bag strip to me.

I've seen one video of bag strip on a tandem canopy that had all the locking stows half-hitched. The canopy came out of the bag 1-2 feet out of the container, with all the rest of the linestows still in place. The canopy opened normally (soft).

One thing to keep an eye on with your bag is the wear on the fabric around the magnets. If they are just held in with para-pack, the lines could wear through the fabric fairly quickly. Have fun with it though! We've made a few variations on the idea, and for the most part, the people that jump them love them. But I'm not comfortable selling the style everyone wants

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[floormonkey 0]

I've got over 500 jumps on one of Kelly's (VSE/Infinity) "lazy bag." VX 104, small HMA line. In that time, 1 brisk opening and 0 line twists. My heading performance during opening actually improved with this bag.

Before using Kelly's bag, I had another of the same style using velcro closure and had similar results.

I usually pack it reserve style, one "layer" at a time, but I also have packed it by figure-8ing the lines over my fingers and shoving the whole thing in at once.

Do the magnets make it difficult/annoying to stow the lines?

Are the magnets so strong the close on your fingers while stowing?

Do you stow one layer or figure-8 the whole mess?

[hookitt 0]

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What you have to avoid absolutely is a line dump when the canopy starts to inflate before the full line stretch

What your describing is bag strip. It's very very uncommon. Hard openings are blamed on line dump and it's not the case. Someone mentioned line dump as a reason for hard openings and it became gospel. I even believed it.


The locking stows need to stay closed until line stretch. That's about it. What you do with the rest of the lines makes no discernible difference in the opening.

Free stowing type bags are great. I'm currently not using one in my Infinity but plan to modify mine with just an open pouch.

My grammar sometimes resembles that of magnetic refrigerator poetry... Ghetto

[Hooknswoop 19]

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One thing to keep an eye on with your bag is the wear on the fabric around the magnets. If they are just held in with para-pack, the lines could wear through the fabric fairly quickly.

1-1/2-inch type III.

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I've seen one video of bag strip on a tandem canopy that had all the locking stows half-hitched. The canopy came out of the bag 1-2 feet out of the container, with all the rest of the linestows still in place. The canopy opened normally (soft).

Ya, tandems are scary.

Derek V

[erdnarob 1]

I mentioned a line dump which not really a bag strip. Line dump is due to too lose rubber bands. I just wonder if the design demonstrated in this thread provides a sufficient resistance to unstow the lines progressively for all kind of parachutes. Though it works for square reserves.
You have to remember that what happens on the ground at very slow speed (in case of a demonstration) is quite different of what happens at 120 MPH. At that speed you have to take in account the momentum of the DB/packed canopy.
Also I think it would a good reminder to explain what happens at opening time:
1) when you throw the pilot chute, this acts like an anchor and almost stops (or slows down a lot) including the DB. In the mean time, you keep on falling at 120 MPH and the line stows give up one after the other (hopefully) to keep order in the lines (avoiding for instance the tension knots). So far the jumper feels almost nothing.
2) at line stretch the jumper starts to accelerate the almost stopped pilot chute/DB, this is the snatch force which can reach for a fraction of second near 2000 lbs (according the Low Speed Aerodynamics studies of Jean Potvin and Gary Peek of University of St Louis and according tests made by John Sherman from jump Shack).
3) then the canopy is becoming exposed to the air and starts to inflate, slowed down by the slider, this is the inflation force.
I certainly don't want the author of the thread to be discouraged. On the other hand I wish him the best. I am myself into new experiments and testing.

Learn from others mistakes, you will never live long enough to make them all.

[superstu 0]

the bags that i use Kelly made for me years ago (2004 range). i personally love them. i've jumped all types and sizes of canopies with them both sub-terminal and terminal and haven't had any problems. easy to pack with or without an RDS, very very very rarely do i get line twists or "line dump". i really have no complaints except when i have to jump a d-bag that has more than 2 rubber bands . like i said, 2000+ jumps and 5-6 years experience with them and still love them.

Slip Stream Air Sports
Do not go softly, do not go quietly, never back down

[Hooknswoop 19]

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when you throw the pilot chute, this acts like an anchor and almost stops

What do you think the slowest average speed of the PC is during deployment?

I have no concerns about line dump or bag strip. There is no reason that the canopy will come out before line stretch compared to a 'normal' d-bag.

Derek V

[Hooknswoop 19]

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Do the magnets make it difficult/annoying to stow the lines?

Not really, I just stuff each 'layer' of line in, moving the magnets apart each time.

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Are the magnets so strong the close on your fingers while stowing?

They are strong, but they don't get my fingers. It is much easier than a normal bag.

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Do you stow one layer or figure-8 the whole mess?

One layer at a time, like a reserve, but not as neat.

Derek V

[ficus 0]

Andre,

The kinetic chain created between the pilot chute and the harness is going to yield in ascending order of resistance. This is true on the ground and in the air.

Even if all of the free stowed lines pay out simultaneously, they are going to achieve tension before the locking stows give. At worst, I could imagine this contributing to tension knots, but it is not going to have an effect on snatch force or hardness of opening.

If the locking stows give first (e.g. small stows, oversized rubber band, very little tension, I think this would actually be difficult to achieve in this design), then the tension holding the D-bag in the canopy must be less than the force required to pay out the free stows for anything out of the ordinary to happen. If that does happen, it's bag strip.

Cliffs Notes: "Line dump" is BS.


Derek,

Sorry for hijacking your thread.

I like your design, but I think it would be easier to make the free stows if the pouch peeled all the way back like the Lazy Bag (or a tail pocket). Do you have an opinion about this?

[Hooknswoop 19]

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I like your design, but I think it would be easier to make the free stows if the pouch peeled all the way back like the Lazy Bag (or a tail pocket). Do you have an opinion about this?

I agree, it would be easier, but would require more work to design and build and increase bulk. Everything is a trade-off. I was leaning towards low bulk and easy to build on this design. The lines pack up very quickly and easily as is.

It was a fun experiment, not as fun as wet risers in the freezer, but still fun.

Derek V

[glgflyer 0]

Where can I find one of the Kelly bags?

[eric.fradet 17]

I've seen one video of bag strip on a tandem canopy that had all the locking stows half-hitched. The canopy came out of the bag 1-2 feet out of the container
_______________________________________________
line dump due to the use of bad rubber bands on a tandem sigma bag, the line stows which have been released are going to float above the bag and can capture the bag

[mjosparky 3]

Derek,

Something like this one. I made it years ago and put over a 1,000 jumps on it with out a problem.

Here is a post on it from June 2005, post #12.

http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=1689990;search_string=d-bags;#1689990

Sparky

My idea of a fair fight is clubbing baby seals

[D11281 1]

That looks pretty much just like the factory bag I got with my new X-210 in a Security Alpha system in 1984.

BB

[skydiverek 54]

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Probably the worst thing though is that red blood cells, with all of their iron, will collect close to the bag, and you will get gian blood clots there, plus you'll be anemic everywhere else in your body.

But you will be anemic only for the duration of the time the magnets are close to you, right? So, in skydiving, that would be about 1 - 2 hours a day (wearing a rig). Is it also "bad", or no big deal in general (long term effects)?

[darkwing 4]

It isn't clear to me from your response above that you understood the real intent of my original post. So let me state that my entire post you responded to was meant to be humorous, as it is entirely absurd.

-- Jeff
My Skydiving History

[skydiverek 54]

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It isn't clear to me from your response above that you understood the real intent of my original post. So let me state that my entire post you responded to was meant to be humorous, as it is entirely absurd.

But strong magnets DO draw blood, don't they?

[jumpwally 0]

Have you seen the new designer smoked sausage from Poland ?

smile, be nice, enjoy life
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[bliston 0]

Anybody see any downside of making a 2 stow bag using the "Wings style" velco free bag design (that keeps the hook clear of the lines)?

Would that be more likely maybe to allow the lines to lock up since they couldn't separate the velcro as they were extracted if need be?

I have 500 HMA on one canopy and might prefer to use velcro instead of magnets...

Ben

Mass Defiance 4-wayFS website


sticks!

[JerryBaumchen 1,047]

Hi Ben,

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Anybody see any downside of making a 2 stow bag using the "Wings style" velco free bag design (that keeps the hook clear of the lines)?

Wings is not the only rig that does it this way.

I do not see any downside.

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Would that be more likely maybe to allow the lines to lock up since they couldn't separate the velcro as they were extracted if need be?

I do not have a 'lot' of square reserve rides but I do have a few. I do not really think that the velcro actually unpeels when the reserve is deployed. YMMV though.

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I have 500 HMA on one canopy and might prefer to use velcro instead of magnets...

I do not see any correlation between type of line & magnets. Do you; just wondering?

I say: Give it a go. Then let us know how it went.

JerryBaumchen

[pchapman 261]

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"Wings style" velco free bag design (

Ah, now I understand:
their velcro free-bag design,
not a velcro-free bag design.

[mjosparky 3]

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I do not have a 'lot' of square reserve rides but I do have a few. I do not really think that the velcro actually unpeels when the reserve is deployed. YMMV though.

Hi Jerry,

I have about 1,000 jumps on the bag I posted about upstream. I can’t ever recall the pocket opening during deployment. When first testing it one of my goals was to prevent bag whip which can lead to other problems. With the lines playing out through the “line channel” the bag remained stable until the locking stows. Then there was quick skip just before the canopy cleared the bag. I went so far as to put snaps on the pocket flap right at the edge of the channel. But I chickened out and went with straight Velcro.

Sparky

My idea of a fair fight is clubbing baby seals

[JerryBaumchen 1,047]

Hi Sparky,

You got me to thinking ( sometimes not such a good thing ).

Since yours was a main d-bag & you wanted to eliminate/reduce line whip, then the more 'locking' that you can get would be a good thing.

The downside is that with greater 'locking' there is the possiblility of line 'jam-up' right at the opening.

It would be interesting to run a series of test jumps on a d-bag that was 'locked' right at that ~2" opening and see if it really makes a difference.

My money says it will not.

OK, great big DUH for me. As I was typing this I suddenly realized that I have a Wings reserve free bag in my shop. As I look at it, the Velcro is installed so that it really does 'lock' the Velcro. It is built in such a manner that it would take a tremendous amount of force to seperate the Velcro.

Since I have never heard of any line 'jam-up' on one of these reserve free bags I would conclude that this is really a non-event.

As I mentioned in another thread; learn something almost every day.

JerryBaumchen

[bliston 0]

Had a couple hours this afternoon and, as we all know, that can be dangerous if if some scrap material and a sewing machine is around.

Please take a look and let me know if you see any potential problems with this design. The sides of the "cover" has tuck tabs, and then magnets seal the top. I went with the triangle covers to help hold the lines in place until the main cover is in place - thought being it would be easier to get the lines neatly in place than with a regular freebag style pocket.

I attached pics of the final product and some along the way, just in case anyone wants to build their own.

Ben

Mass Defiance 4-wayFS website


sticks!

[LouDiamond 1]

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let me know if you see any potential problems with this design

I'd recommend that you sew a piece of cotton duck or other non nylon material along the edge between the magnets where the lines exit. The friction of the lines during extraction and before the magnets release could cause friction burns and or damage /deterioration of the lines over time.

Your design still uses 2 rubber band/tube stow locking stows correct?

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