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nigel99

Cutting the loop or pulling the pin?

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How exactly are you doing this mechanically in side the housing. I'm not clear on how it's working mechanically and still allowing full extraction of the rip cord. And what is the story on the gas? How is it contained? Does any of it escape from your pushers, pullers, or the inline? Is there a stop on the ripcord that you push against to move it and how much slack do you have to allow the rip cord to float and stretch? How long is your control stroke? How much compression is there in your housing? How will the housing be mounted? Tacked down or with a clamp like the old school housings that attached to a plate going to the first cone or grommet or what ever? I can see this working for you but are you looking at using this same design on other rigs? What about when there is more space or... softness, stretch between the end of the housing and the grommet? You can't just tease people like this. It's cruel.

Lee
Lee
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www.velocitysportswear.com

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How exactly are you doing this mechanically in side the housing. I'm not clear on how it's working mechanically and still allowing full extraction of the rip cord. And what is the story on the gas? How is it contained? Does any of it escape from your pushers, pullers, or the inline? Is there a stop on the ripcord that you push against to move it and how much slack do you have to allow the rip cord to float and stretch? How long is your control stroke? How much compression is there in your housing? How will the housing be mounted? Tacked down or with a clamp like the old school housings that attached to a plate going to the first cone or grommet or what ever? I can see this working for you but are you looking at using this same design on other rigs? What about when there is more space or... softness, stretch between the end of the housing and the grommet? You can't just tease people like this. It's cruel.



Kinda makes you wonder don't it?:)

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And what is this going to do to Booths obsession with spectra rip cords? Will he have to start buying stainless ripcords from Jump Shack? Or is he going to tie a knot in his spectra at a certin point on so your inline can push on it?



Ever try to push a rope. Its something like that.;)

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charliemike

***But if the reserve pin is bent, it will not be able to pull, correct? (has this ever happened to such extend, though...?). How many pounds of force are generated with the "pull"?



One less worry with the Racer's pin protection.:)
Bent pins have been reported just due to the tension on the loop, but even a racer is vulnerable to a bend from external forces. It does not good for it to be said that a puller can provide 80 or whatever pounds of force, by itself that number does nothing to show it can overcome a bent pin, and who knows how much a pin might be bent?
People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am

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Bent pins have been reported just due to the tension on the loop,



This is a made up "What if". In the last 40 years nearly 100% of all rigs jumped had cloth loop and standard ripcord pins. To my knowledge there have been no fatalities attributed to the bent pins. Sure some have been found and I am sure some have been pulled bent. But no one has ever gone in from one. Cutters on the other hand, which represent only a small percentage of the overall population, have cause several fatilities and caused one company to close.
If this isn't a "No Brainer" I don't know what is.

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nigel99

A few times in recent threads about slower deploying reserves or TSO a few respected riggers have mentioned there is a difference between cutting the loop and pulling the pin.

It is fairly clear that some knowledgeable people feel that there is a difference that can be attributed to the 'how' the deployment is initiated. I'm interested to learn more?



There is a difference. If the pin is pulled the flaps can slide off the closing loop without much resistance. With a cutter the loop is cut at the bottom, in most cases, and the loop can become trapped and prevent the PC from clearing the flaps. This is most likely to happen if the loop is too long. This was addressed by at least one manufacture with a SB changing the location of cutter.

Sparky
My idea of a fair fight is clubbing baby seals

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To my knowledge there have been no fatalities attributed to the bent pins. Sure some have been found and I am sure some have been pulled bent. But no one has ever gone in from one.



Well, this may qualify as an incident. The pins were said to have some bend in them by Nancy herself.

Also, the floating ripcord theory could be a mistaken theory.

How do you not know that he was pulling all the way until impact and the handle was probably released AFTER the impact?

Here are the two fatalities:

http://www.dropzone.com/cgi-bin/forum/gforum.cgi?do=post_view_flat;post=3678254;page=5;sb=post_latest_reply;so=ASC;mh=25;


MEL
Skyworks Parachute Service, LLC
www.Skyworksparachuteservice.com

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The bends occurred due to impact. There were corresponding dents in the grommets from the strike of the pin blades.



I have never heard of or seen these from an impact.

Also, probably the two bodies impacted before the rig did.

Lastly, the pair loaded the top flap which then loaded the pins,loop, and etc....

The reason that one pin was bent more was the way the load was applied. The top pin is probably the one that was bent the most just by the angle of the dangle is my guess.

MEL
Skyworks Parachute Service, LLC
www.Skyworksparachuteservice.com

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Well, this may qualify as an incident. The pins were said to have some bend in them by Nancy herself.

Also, the floating ripcord theory could be a mistaken theory.

How do you not know that he was pulling all the way until impact and the handle was probably released AFTER the impact?

Here are the two fatalities:

http://www.dropzone.com/..._reply;so=ASC;mh=25;


It doesn't qualify. There was video of the hole thing, He never graspsed the ripcord handle.
The pins might have been bent as a result of impact but they had nothing to do with the incident. The rigger admitted to misrigging the RSL under the top flap when he was changing the CYPRES batteries. The ripcord was pullable but wasn't pulled. The handle was not in the pocket but because the pocket had been modified by the user the handle came out and floated and could have been grabbed easly and the AAD didn't fire. Nothing to do with bent pins.

Keep looking

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There was video of the hole thing, He never graspsed the ripcord handle.



Handy cam Video?

I just paged through several tandem cutaways with handy cam video and most you cannot tell much of what is going on until after the reserve canopy is deploying.

Just saying....

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The pins might have been bent as a result of impact but they had nothing to do with the incident.



I would have to think they were bent from the shock loading of the RSL-top Flap-Quick-Loop-Pins.

A quick shock load calculation of a 500 lb load dropping 6 inches equals 2296 lbs. This is with stranded 1/4" wire cable as a medium in the calculation. It would be lower with material that had more elasticity and also lower with lesser travel distance.

Of course we know that we never achieved that amount of force or the quick loop would probably have broken.

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The ripcord was pullable but wasn't pulled.



I am guessing that you re-created the loaded scenario with two people in the harnesses (450 lbs) and then pulled it.

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The handle was not in the pocket but because the pocket had been modified by the user the handle came out and floated



So, in the video, the handle just popped out of place????

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Nothing to do with bent pins.



John,
Your RSL system (or mis-rigging of it) has a built in error trap which played a role in these fatalities whether you will admit to it or not.
....Yes, I know read the manual!

The reason that I brought this up is this. I think that the pin puller is the way to go provided there are no bent pins. It is a better way to go IMHO.

But.....Ironically your system (with the RSL attached) has the highest probability of bent pins. More so that any other rig out there with the above scenario.

MEL
Skyworks Parachute Service, LLC
www.Skyworksparachuteservice.com

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John,
Your RSL system (or mis-rigging of it) has a built in error trap which played a role in these fatalities whether you will admit to it or not.
....Yes, I know read the manual!

The reason that I brought this up is this. I think that the pin puller is the way to go provided there are no bent pins. It is a better way to go IMHO.

But.....Ironically your system (with the RSL attached) has the highest probability of bent pins. More so that any other rig out there with the above scenario.

MEL ***

Believe it or not we did test it and as you say the caveat is in the manual. We tested it in the air as well as on the ground. While suspended under canopy, in the air, by the RSL x-connector locked under the top flap after a cutaway. The test jumper was able to pull the ripcord and the reserve deployed normally. There were no bent pins. We studied this on the ground before doing it. Strangely when the top flap is loaded there is no noticeable increase in force on the pin pull. I attribute this to the fact that the loop in tight from pin pressure in the packed position and the flap is loading the loop in a perpendicular direction while the flap itself is acting as a pulley reducing the load. Even the shock of the cutaway did not bend the puns.
We knew, 30 years ago, that some dummy would make this mistake so we studied it and put it in the manual. We know of 2 occurrences of this error over that time period and that covers some 30,000 RSL equipped rigs.

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I think the next video should be made using a high speed thermal imaging camera, looking at each end of the housing when the pyro fires!! That would be narley! lol;)


Just a couple of thoughts that I am sure have been thought of;

Will you be sending Nomex gloves with these as well in case the jumper is pulling the handle when it fires?…:o

I’m sure airlines will love the open explosive arrangement as well [:/]

Very interesting though...

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I think the next video should be made using a high speed thermal imaging camera, looking at each end of the housing when the pyro fires!! That would be narley! lol


Just a couple of thoughts that I am sure have been thought of;

Will you be sending Nomex gloves with these as well in case the jumper is pulling the handle when it fires?…

I’m sure airlines will love the open explosive arrangement as well

Very interesting though...



I guess we should do that for the cutters when they fire inside the reserve container. They both use the same power amd method. The only difference is that we just drive the ripcord cable and the cutter drives a cutter piston. Same amount of gas same amount of power. Same pyro and same airline consideration and if you need gloves to handle your cutter after it fires you will need them for this. If you don't you won't for this either.


JS

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In a cutter the expanded gasses are contained with in the cutter.... No hot gases escape... it is a contained explosive device, and that is why air lines allow them to be brought on a airliner.

This device has a cylinder that is not sealed the pin end, and the piston, (the swaged ball on the cable) is expelled from the cylinder during operation… So not only are there hot gasses escaping out the pin end (under great pressure), prior to the piston expulsion, once the piston is expelled from the cylinder, the remaining pressure charge (of hot gasses and any residual burring charge) will be vented out the handle end of the housing, (where the jumper’s hand will be if they are pulling the handle). If you look at you second video, you will see the CO2 blowing out the handle end of the housing, and that is at a much lower pressure then the pyro charge will be.

Friday, I was testing a firing circuit for a new AAD I am designing, and fired two cutters right on the bench, no gasses expelled, only a click of the piston hitting the end of the cylinder. My partner picked up one cutter and mentioned that it was hot, I said yes it is, it has the gasses from a pyro charge “trapped inside it”..

In order to generate the 80-120 lbs of pull mentioned in a previous post, the pressure required to do so will be way higher than the CO2 cartridge’s charge used in the demo that spit CO2 out the handle end.

I assume your cylinder ID is around .250 inches (so lets call the piston dia .250), and the rip cord cable I have here is about .090 inches in dia… The area for a .250 dia is .0490873 sqin, and the area for .090 dia is .0063617 sqin… now to get the piston area, we have to subtract the cable area from the cylinder area, so, .0490873-.0063617= .0427256 sqin of piston area for the gasses to push against… Now that we know that, we can determine the amount of gas pressure required to generate any given pull force…. So to generate 100 lbs of pull, we have to divide 100 lbs by the surface area of the piston, (how many sqin there are to push against), .0427256 sqin, which = 2340.5172 PSI.
This means that it will take 2340 PSI of gas pressure pushing on the piston area to generate 100 lbs of pull on the rip cord.

Given that the pin end of the rip cord end of the cylinder is not sealed, there will be hot gasses expelling out of it like a rocket motor at 2000+ PSI, additionally, once the piston is expelled from the cylinder, the remaining pressure will blow out the handle end, right where your hand will be. This is not a contained explosive device, as the gasses are vented to the atmosphere at a high volume by design. Yes, cutters will be hot to the touch after activation, but they are not a blow torch blowing hot and burning gasses directly on a jumper’s hand.

Plus, given the high leakage rate of the cylinder design, and the need to sustain a high rate of pull force through the entire pin length, (+ a little extra to get it moving and some reserve for the end), the amount of gasses volume that will need to be generated and vented will be more than a traditional cutter. It will be interesting to see the pull force curves when you get to that point.

Further, given that the replacement pyro gas generators are not assembled in an assembly that contains the gasses that are generated when the pyro is activated, it is an open explosive, and anyone receiving, handling, or storing, such a device is required to have an explosives handling and storage license from the ATF, and a properly rated magazine to store such charges. I know this because I am going through the process to get a license right now.

Technically, it is illegal to send an open gas generator (explosive device) to anyone (individual or business) that does not have the proper ATF license and storage capabilities. This means when a jumper needs a replacement gas generator, they, or their rigger, will be required to have a explosives handing and storage license, as well as the other required safety equipment required by the ATF to handle open explosives, in order for a new gas generator be to shipped to them. The ATF is really sensitive to explosives being shipped around lol.

The concept is interesting, but needs more refinement, as in contain the hot burning gasses with in the housing so no one gets burned, or their nylon container, and or, jump suit doesn’t get set on fire when they are at 1000 Ft AGL with lots of wind to feed the flames.. At best they should hope for a burnt hand…

CO2 and compressed air are one thing, explosive generated gasses are totally different.. Perhaps a video of a rigged system, with pull force instrumentation to measure the force generated and the time to pack opening from activation would be next. Make sure to have both ends of the rip cord housing in the camera frame so we can watch the hot gasses blowing out the ends of the housing.

I know you do not like cutters, and I do think that this is an interesting approach to an alternative activation method, but as I said, it needs to be refined more before it sees the market…

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