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pchapman

Packing line equalization diaper with all lines in diaper?

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Does that make any sense at all, packing a line equalization diaper with all lines inside the diaper?

I heard a newer rigger say he had someone instruct him that one could or should do that. Sounded a little crazy. Never heard of anyone doing that and don't plan to do that, but curious what others know.

The idea was that one couldn't have a failure of the diaper as could theoretically happen, if there was some entanglement with the half of the lines that went directly to the canopy (thus never tensioning the other set of lines that held the diaper closed). Say by an unstable pilot bailing out.

But if both sets of lines went to the diaper, the elastics there would absolutely have to be set up to be really tight or something, so that they wouldn't pull out until all the lines pulled out of the pack tray elastics. If the diaper released early, it would be almost as if it were a non-diapered canopy, something diapered canopies were generally not designed for.

It seemed like an idea not fully thought out, creating one large potential problem in place of an extremely rare problem. Or am I missing something?

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I've never heard the term line equalization diaper but i assume you mean a Strong diaper with half the lines in it. Putting all of lines in the diaper to lock it with the rest of the lines in the container completely defeats the purpose, may/ will result in the diaper releasing before the lines in the container deploy greatly increasing the chance of a malfunction, and simply doesn't follow the manual or the tso'd configuration.

Educate the new rigger to follow the manual and why, and try to educate the rigger that told him to do it that way not to try to make it up as he goes.

This is one of the worst cases of "creative" rigging I've heard of.>:( I hate to think of what he is doing to make those locking stows tight enough to not come out.[:/] While his concern may be correct his solution is no better and illegal in the US in not following the manual. If in the U.S. he's in need of reevaluation by the administrator.

I'm old for my age.
Terry Urban
D-8631
FAA DPRE

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He might have been confused by the diaper design. Some Strong diapers can be used as Type-2 deployment (half the lines used to lock the diaper, line stowage otherwise on the pack tray) _or_ as Type-4 (all the lines stowed on the diaper). We choose one or the other based on manufacturer instructions -- mostly for the bulk distribution that makes the pack look nice.

Mark

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Never heard of that packing technique before??????

Was he referring to a Type 2 diaper (with only the left line group locking the diaper closed)?

Like the other poster said, he may be confusing it with a Type 4 diaper. Strong and Butler manuals instruct riggers to pack Type 4 as Type 2 or Type 4 depending upon desired bulk distribution.

For example, all but the oldest Strong, 26 foot diameter, conical canopies made of low-porosity fabric have Type 4 diapers with three locking stows (rubber bands). When packing a Strong LOPO, round canopy into a Strong Para-Cushion PEP, I always stow the left line group on the diaper. The right line group remains outside the diaper. The rest of the lines get stowed in the pack tray because that is the method illustrated in the Strong manual and it is important to pack most of the line bulk under the pilot chute to provide the spring with a solid platform to launch.
OTOH when packing Strong LOPOs into most other containers, I stow all the lines on the diaper.
The only exception is when I am packing a Strong LOPO into a thin container (e.g. Long Softie) then I revert to Type 2 line stowage to spread line bulk and make the pilot more comfortable.

Packing in a manner not illustrated in the manual (per manufacturers' instructors) turns the user into a test-jumper ... not wise on gear that was perfected 40 years ago.

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Thanks everyone.

The rigger never actually packed anything the incorrect way, and just related the story to me as "I was told that....", so that's good. Hopefully the error cropped up for the reasons others suggested -- that one could change from half the lines in the diaper to all the lines in the diaper, but only in the context of switching between completely different type 2 and type 4 packing, where approved.

As for my using the term "line equalization diaper", that's funny. A printed page in my original rigging course described that line equalization releases that sort of 2 grommet diaper so I happened to start using that term in my logbook to distinguish between diapers in a more descriptive fashion than type number or grommet numbers. You've got full stow in a couple orientations (with or without bottom flaps), and you've got line equalization. After that, the issue never came up that it was an informal description rather than an accepted term that anyone else uses...

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betzilla

I found it in a packed rig once. Creepy. Also annoying that I had to spend all that extra time removing rubber bands from the diaper, and installing them in the container.



Been there, seen that... from an older rigger whom was known to disregard the manual and "knew better" than the mfg. (my DPRE and I had a chat...)


Walk on road, hm? Walk left side, safe. Walk right side, safe. Walk middle, sooner or later get squish just like grape. Here, rigging , same thing. Either you full diaper stow "yes" or full diaper stow "no." You full stow "guess so," sooner or later get squish just like grape.

All lines on diaper (in an appropriate container) - safe.
1/2 lines closing diaper, all lines in container) - safe.
all lines closing diaper, all lines in container - squish.

JW
Always remember that some clouds are harder than others...

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dpreguy

fca summary is correct.

And; with half of the lines in the diaper 'choice #2' - tight rubber bands on the diaper lines=per Strong. For a while they even recommended a double wrap on them.



I know that things can be different in the air than on the table, but when I unpack a Type II (1/2 line locked diaper) system, I want to see all the full line stows in the pack release before the diaper. If not, you need to use fresher/snugger bands on the diaper.

Failure of this diaper stowage design is the deployment equivalent of bag strip for a ram-air canopy. Canopy (opening) is exposed to the air and starting to inflate prior to line stretch. Either a very hard opening and/or lines knotting on whatever they want to as they flail around... Either way, your gonna have a bad day.

JW
Always remember that some clouds are harder than others...

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Hi Peter and all interested
I was surprised that you brought up a subject concerning diaper line set up in 2016.

I have had 2 Strong reserves in the 70s:
a) a 26' LoPo PN: 1012
b) a LoPo Lite PN 1014

a) The first case (26' LoPo PN 1012) had only half of the lines (the left set) going below the flap of the diaper with 3 stows using grommets and you had to cope with the difference for stowing the lines (both sets) in the container (see in attachment)

b) the second case (LoPo Lite PN 1014) needed to have ALL THE LINES going below the diaper flap, with 3 stows using the grommets and the rest of the lines was stowed ALL on the diaper itself in rubber bands installed just beside the grommets in a dicreasing distance way.(see in attachment)

The idea for the second case was that Strong wanted to have diaper first deployment then after diaper extension, line extraction well away from the jumper to decrease the chance of entanglement with the jumper

But a drawing is equivalent to 1000 words, have a look at the 2 documents provided by Strong when I bought those reserves (see in attachment)
Learn from others mistakes, you will never live long enough to make them all.

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erdnarob

Hi Peter and all interested
I was surprised that you brought up a subject concerning diaper line set up in 2016.

I have had 2 Strong reserves in the 70s:
a) a 26' LoPo PN: 1012
b) a LoPo Lite PN 1014

a) The first case (26' LoPo PN 1012) had only half of the lines (the left set) going below the flap of the diaper with 3 stows using grommets and you had to cope with the difference for stowing the lines (both sets) in the container (see in attachment)

b) the second case (LoPo Lite PN 1014) needed to have ALL THE LINES going below the diaper flap, with 3 stows using the grommets and the rest of the lines was stowed ALL on the diaper itself in rubber bands installed just beside the grommets in a dicreasing distance way.(see in attachment)

The idea for the second case was that Strong wanted to have diaper first deployment then after diaper extension, line extraction well away from the jumper to decrease the chance of entanglement with the jumper

But a drawing is equivalent to 1000 words, have a look at the 2 documents provided by Strong when I bought those reserves (see in attachment)



The second case, newer 3-closing/full stow diaper was an option for packing the Strong 26' LoPo/Mid-lite in a container that did not have container line stows as part of its packing procedure.

In the Strong Paracushion up to the present day, the 3-stow diaper is used with lines split to use only the left side to close the diaper and all the rest stowed in the container.

The diaper/canopy can be used in either type of packing method, dependent upon the needs of the container.

Where we see the problem is when people use all lines to close the diaper and then stow the remaining lines in the container. This will cause great trouble.

JW
Always remember that some clouds are harder than others...

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On 4/25/2016 at 5:15 AM, fcajump said:

...

Where we see the problem is when people use all lines to close the diaper and then stow the remaining lines in the container. This will cause great trouble.

JW

 

 

Always remember that some clouds are harder than others...

 

Silliness done by people who do not understand the deployment sequence.

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On 3/26/2016 at 8:51 PM, pchapman said:

' ... line equalization diaper ... "

That is reallllly old and cumbersome terminology.

Why invent new terminology?

About 40 years ago, John Sherman coined the terms: Type 2 diaper, etc. and most riggers have been using that standardized terminology ever since.

Type 1 with all the suspension lines stowed in the pack tray. Now considered obsolete.

Type 2 diaper with the left line group stowed in 2 or 3 locking rubber bands on the diaper with the rest of the suspension lines stowed in the pack tray. Considered obsolete for most containers except for Strong Para-Cushion pilot emergency parachutes where the suspension lines' bulk provides a launching platform for the pilot-chute.

Type 3 diaper with 2 locking stows and all of the suspension lines stowed horizontally on the diaper. Invented by Hank Asquitto and used on Piglet and Phantom, etc. round reserves.

Type 4 diaper with 2 or 3 locking stows and all suspension lines stowed vertically on the diaper. he industry standard for round civilian canopies made since the 1960s (e.g. Strong Mid-Lite round reserve canopy). Also seen on a few early squares (e.g. Hobbit and reefing line Cloud).

Type 5 deployment bag with 2 or more locking stows and all of the suspension lines stowed on the D-bag (rubber bands or in a pocket).

Type 6 Sleeve - mentioned in the FAA Parachute Riggers' Handbook (2015 revision)

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In defense of half stow diapers.

Although it's a less intuitive system and there can potentially be issues with it, I will say that it also has advantages. A lot of it centers around mass and weight of the lines. Problems show up in both high and low speed deployments. 

 

I'll start with low speed stories. The dz I started at still had round reserves on the student rigs. On the whole this wasn't a bad thing as it made two out's relatively benign in most cases. The rigs had a mix of reserves. We had FXC's. I noticed that the half stow strongs deployed a lot smoother and cleaner in low speed two out sinarios. The weight of the lines was in the tray. As the pilot chute deployed the canopy there was never a sudden weight of a heavy diaper with full stow lines. On the other hand I watched a malfunction where a phantom deployed beside a low speed malfunctioning main. The pilot chute and canopy went up but when the diaper fell out of the tray it stalled struggling to lift the weight of the diaper. It just floated beside the main actually sinking lower as the main turned wrapping the lines of the reserve around every thing till the pc caught enough air to finish in showing the diaper and the reserve started to fill and deploy at which point every thing started to unroll. It all turned out fine. The lesson I took away from watching that was first the importance of an adequate PC. Second to not disregard the weight of the diaper.

 

High speed. On high speed higher then normal terminal deployments the sudden mass of the full stow diaper can put a lot of strain on the canopy. We had a failure where we snapped a tape on the radial seam that the diaper was attached to. Wound up adding a heavy tape on top running up to the apex with a loop on the end to support the weight of the diaper during deployment. Please note that the military did the same thing, or similar, with the adoption of the quarter bag. They found that they needed a 1" type 4 tape just to lift the weight of all those lines. I'll give you another example of a high speed failure caused by a full stow diaper. This was on a phantom at an air show. And yes it was the tighter diaper. It doesn't matter it's the nature of the design. When it tried to lift the diaper the crown line for the seam that held the diaper acted like the rope in a pulley with the PC bridle. It pulled the #1 seam out of the fold in the diaper. That gore caught air and snapped the line off at the canopy. The inflating skirt pulled out the next two Gore's and snapped them. This continued all the way around the canopy breaking the lines at the skirt till the last one broke at the link. Pilot went in under just the lines. All of this could have been avoided it there was an independent tape or a loop in the crown line. Based on the radar data the canopy should have survived if the diaper had not failed. 

 

No one's denying that a full stow diaper is much better staging for deployments. But it's also a significant weight concentration which can add it's own issues.

 

As to packing it. Lack of knowledge of how it functions is a failure of the rigger not the system.

 

Lee

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5 hours ago, RiggerLee said:

This was on a phantom at an air show. And yes it was the tighter diaper. It doesn't matter it's the nature of the design. When it tried to lift the diaper the crown line for the seam that held the diaper acted like the rope in a pulley with the PC bridle. It pulled the #1 seam out of the fold in the diaper. That gore caught air and snapped the line off at the canopy. The inflating skirt pulled out the next two Gore's and snapped them. This continued all the way around the canopy breaking the lines at the skirt till the last one broke at the link. Pilot went in under just the lines. All of this could have been avoided it there was an independent tape or a loop in the crown line. Based on the radar data the canopy should have survived if the diaper had not failed.

Just to be clear, you're saying the inertia of the heavy diaper & lines basically pulled down on that side, causing the opposite seam to get pulled up.

Do you remember the circumstances of this one? (Year, location, anything?)

I have tried to keep track of any Phantom failures but hadn't heard of that one. National of course isn't big on advertising their canopy failures.

Certainly there was the one where a pilot bailed out at very high speed, and blew all the lines off his Phantom. (Su-29, 1996, Louisiana, radar showed aircraft at 220 knots at some point). 

Your case was definitely a different one?

(The way National certified the Phantom was pretty sketchy, making 'engineering' judgements or assumptions that meant their canopy may not have been given tests anywhere close to the strength requirements of the old NAS804 used in the certification. At least, that's what one can infer from the very dry, factual statements by the FAA when investigating that 1996 accident. )

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Probably the same accident. I was told this story, had it explained to me by an FAA guy from the FSDO in Dallas. Guy named Gene Bland. Pilot broke the plane in some way. Took wings off? He had good radar plots giving him speed across the ground. He had video and impact data showing the impact angle. From that he calculated the air speed of the lawn dart. They had video of the opening of the canopy. He believed that he had good numbers on the deployment speed. He knew the pilots weight. Based on those numbers he thought that the loading should have been not within what it was certified for but he believed that it was within what it had supposedly been tested to. Bland was like a dog with a bone. He wanted to force them to redo the heavy drop test. No one else cared. He lost that fight.

 

You could see from the canopy how the lines failed. It's easy to understand the mechanics if you just play with the diaper. The phantom was never the strongest canopy out there. You could argue whether it would have survived or not. It never got the chance. It did not blow out it's crown. It did not split a gore. It did not fail in any of the ways that canopies blow up. The diaper failed to stage the opening and it broke in a very predictable way because of it. 

 

To be clear, I like Ashudo phantom stile diapers. It was just a failure of imagination. Thinking of the folded canopy as one solid thing rather then as a dynamic flexable object capable of moving and shifting. All you would need is a loop in that crown line. A peace of tape with a loop. An eye in the line. Maybe a heavier tape on that seam. I've been caught out on that as well. I snapped a tape above a diaper on a canopy I built. It was a pain to sew that thing back together and when I did you can bet it had a heavier tape on that gore.

 

Don't confuse it being a bad design with it being an incomplete design. It's just missing a small element. Full stow choaker diapers put the same stress on that tape. I think all canopies should have heavier tapes on that seam. The military apparently agreed on the C9 with the quarter bag.

 

Lee

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18 hours ago, pchapman said:

Just to be clear, you're saying the inertia of the heavy diaper & lines basically pulled down on that side, causing the opposite seam to get pulled up.

Do you remember the circumstances of this one? (Year, location, anything?)

I have tried to keep track of any Phantom failures but hadn't heard of that one. National of course isn't big on advertising their canopy failures.

Certainly there was the one where a pilot bailed out at very high speed, and blew all the lines off his Phantom. (Su-29, 1996, Louisiana, radar showed aircraft at 220 knots at some point). 

Your case was definitely a different one?

(The way National certified the Phantom was pretty sketchy, making 'engineering' judgements or assumptions that meant their canopy may not have been given tests anywhere close to the strength requirements of the old NAS804 used in the certification. At least, that's what one can infer from the very dry, factual statements by the FAA when investigating that 1996 accident. )

Hi Peter,

The 'story' that I heard was that he stood up in the aircraft & pulled the ripcord, hoping to use the canopy as a pull-out device.

Jerry Baumchen

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5 minutes ago, JerryBaumchen said:

Hi Peter,

The 'story' that I heard was that he stood up in the aircraft & pulled the ripcord, hoping to use the canopy as a pull-out device.

Jerry Baumchen

Yes Jerry, I heard the same story from Manley Butler.

The pilot in question was a young ferry pilot, ferrying the aerobat from one airshow to the next. He did something stupid enough to disable the airplane, so stood up and pulled the ripcord. The canopy inflated before his legs left the cockpit. The extra opening shock tore the lines off of that Phantom.

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In another failed Phantom story, one of the US Navy test jumpers told me about the time they used a Phantom to slow a test slug/bomb/missile/drop tank/whatever. The drop plane was an F-4 Phantom doing 600 knots. The first frame of the film showed the canopy at line stretch and the second frame showed only reinforcement tapes! All the fabric blew off in that split-second between frames!

Hah!

Hah!

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