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Cutting the loop or pulling the pin?

 

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nigel99  (D 1)

Sep 1, 2013, 1:17 AM
Post #1 of 169 (11926 views)
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Cutting the loop or pulling the pin? Can't Post

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?


Deyan  (D 322)

Sep 1, 2013, 1:37 AM
Post #2 of 169 (11786 views)
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Re: [nigel99] Cutting the loop or pulling the pin? [In reply to] Can't Post

That's how bad rigging may contribute to slow reserve deployments.

http://www.youtube.com/watch?v=HYIUjKGxagI

This video was posted in at least 3 other threads.


(This post was edited by Deyan on Sep 1, 2013, 1:49 AM)


nigel99  (D 1)

Sep 1, 2013, 2:54 AM
Post #3 of 169 (11722 views)
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Re: [Deyan] Cutting the loop or pulling the pin? [In reply to] Can't Post

Deyan wrote:
That's how bad rigging may contribute to slow reserve deployments.

http://www.youtube.com/watch?v=HYIUjKGxagI

This video was posted in at least 3 other threads.

Very interesting, but are you saying that would NOT have happened when pulling the pin?


jumpwally  (D License)

Sep 1, 2013, 4:31 AM
Post #4 of 169 (11660 views)
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Re: [nigel99] Cutting the loop or pulling the pin? [In reply to] Can't Post

Try the same thing with a racer.....


shropshire  (C License)

Sep 1, 2013, 5:12 AM
Post #5 of 169 (11622 views)
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Re: [jumpwally] Cutting the loop or pulling the pin? [In reply to] Can't Post

"other pop-top harnesses are available" :-)

Kind of loving my Teardrop right about now.


virgin-burner

Sep 1, 2013, 6:34 AM
Post #6 of 169 (11564 views)
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Re: [shropshire] Cutting the loop or pulling the pin? [In reply to] Can't Post

how MUCH are you loving it!? Tongue


adamUK  (C 104423)

Sep 1, 2013, 7:18 AM
Post #7 of 169 (11527 views)
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Re: [shropshire] Cutting the loop or pulling the pin? [In reply to] Can't Post

Are teardrops still RSL unfriendly?


shropshire  (C License)

Sep 1, 2013, 7:26 AM
Post #8 of 169 (11518 views)
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Re: [adamUK] Cutting the loop or pulling the pin? [In reply to] Can't Post

I can't say - sorry .. no RSL on mine..


EDITED : I just looked on-line and RSL is offered as an option TSE Tear Drop SF


(This post was edited by shropshire on Sep 1, 2013, 7:49 AM)


adamUK  (C 104423)

Sep 1, 2013, 7:39 AM
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Re: [shropshire] Cutting the loop or pulling the pin? [In reply to] Can't Post

Mmm. I remember them being a bit difficult to rig with an RSL but that was a long time ago. Glad it's sorted.


Deyan  (D 322)

Sep 1, 2013, 8:17 AM
Post #10 of 169 (11426 views)
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Re: [nigel99] Cutting the loop or pulling the pin? [In reply to] Can't Post

nigel99 wrote:
Very interesting, but are you saying that would NOT have happened when pulling the pin?

It's a wild guess, but I think that with the pin out, the RPC would've clear the flaps without hesitation. It will not be the greatest launch though. Maybe 2 ft or less, but at least out of the rig.

http://www.youtube.com/watch?v=V7bFy4FoNiA


riggerrob  (D 14840)

Sep 2, 2013, 6:32 PM
Post #11 of 169 (10925 views)
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Re: [nigel99] Cutting the loop or pulling the pin? [In reply to] Can't Post

With an (older-style) pin-puller (FXC 12000, KAP-3 or Sentinel Automatic Activation Devices), the reserve deploys pretty much the same way as if the ripcord was pulled.
One disadvantage is that the pin-puller's power cable has to the strapped to the last flap (or next-to-last-flap), making it stiffer and more difficult to push out of the way.
Racer is the only reserve container that opening is not adversely affected by a pin-puller).

The disadvantage with loop-cutter style AADs (Argus, Astra, Cypres, M2 and Vigil) is that it is difficult to know how long the closing loop is. The longer the closing loop, the greater the risk of it causing a pilot-chute hesitation.

The greatest risk is if the closing loop gets squeezed between two grommets, then the additional friction can cause a pilot-chute to hesitate.

The best answer is to stack the tolerances in your favour.
Start by choosing canopies that are compatible with your container (as listed in the container manual). S

Secondly, hire a rigger who has read the manual for your container.

Thirdly, read the manual yourself.

Fourthy, ask you rigger how long a reserve closing loop he installed.

Fifth, if his answer is more than a half inch longer than recommended in the manual, pull the ripcord and tell him to try again.

Hint: the Vector/Micron/Sigma/Sidewinder manuals recommend reserve closing loops 4.5 inches long (tied to a Cypres washer).
The Javelin manual recommends reserve closing loops just over 2 inches long (tied to a Cypres washer).


nigel99  (D 1)

Sep 2, 2013, 8:35 PM
Post #12 of 169 (10817 views)
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Re: [riggerrob] Cutting the loop or pulling the pin? [In reply to] Can't Post

riggerrob wrote:
With an (older-style) pin-puller (FXC 12000, KAP-3 or Sentinel Automatic Activation Devices), the reserve deploys pretty much the same way as if the ripcord was pulled.
One disadvantage is that the pin-puller's power cable has to the strapped to the last flap (or next-to-last-flap), making it stiffer and more difficult to push out of the way.
Racer is the only reserve container that opening is not adversely affected by a pin-puller).

The disadvantage with loop-cutter style AADs (Argus, Astra, Cypres, M2 and Vigil) is that it is difficult to know how long the closing loop is. The longer the closing loop, the greater the risk of it causing a pilot-chute hesitation.

The greatest risk is if the closing loop gets squeezed between two grommets, then the additional friction can cause a pilot-chute to hesitate.

The best answer is to stack the tolerances in your favour.
Start by choosing canopies that are compatible with your container (as listed in the container manual). S

Secondly, hire a rigger who has read the manual for your container.

Thirdly, read the manual yourself.

Fourthy, ask you rigger how long a reserve closing loop he installed.

Fifth, if his answer is more than a half inch longer than recommended in the manual, pull the ripcord and tell him to try again.

Hint: the Vector/Micron/Sigma/Sidewinder manuals recommend reserve closing loops 4.5 inches long (tied to a Cypres washer).
The Javelin manual recommends reserve closing loops just over 2 inches long (tied to a Cypres washer).

Thanks Rob, that is the kind of information I was looking for. The guy who packs my reserve religiously sticks to the closing loop lengths (I know cause he's taken issue with two other peoples loops when I've been repacking with him).

My curiosity is a general interest issue rather than a specific concern about my equipment.


RiggerLee

Sep 2, 2013, 9:09 PM
Post #13 of 169 (10796 views)
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Re: [riggerrob] Cutting the loop or pulling the pin? [In reply to] Can't Post

Loop cutter AAD's. I don't see pilot chute launch as being affected by compatibility. Many other things are, but not PC launch. The two major factors I've seen are container design, and Rigging. Container design, other then choice or rig is out side your hands. Even small changes in the pattern set or construction can affect hesitations. Although they may not publicly advertise it this is something manufacturers are putting a lot of effort into. Rigging is about the only thing with in your control. I don't like the idea of published loop lengths. There are too many variables, from canopy selection to bulk distribution in the pack job. Some canopies just pack up bigger then others. Or if you put an optimum in there it will obviously be thinner. Humidity is another large factor. So the loop length that is right for one rig may not be right for a container of exactly the same size. And the loop that is right for one rigger may be too long or too short for another.

The real root question is how much tail is left locking the flaps closed when the loop is cut. I phrased is that way on purpose. That is in truth of what is really happening. I'm not saying cutters are a bad thing. They solve a host of problems and make what we conceder modern AAD's possible. But it does come with issues. For most rigs the loop length does not effect the amount of tail that is left. It's the amount of looseness. Big thick rig stuffed full of a bulky canopy, long loop tight as fuck, no problem. On the other hand, smaller canopy fluffed and stuffed with a shorter loop, loosens over time, and the pilot chute wobbles. Now you have an extra inch of loop passing through the lose spring to the cutter below the sub flap. The biggest problem here is old school sloppy lazy rigging practices. A good example would be a relatively thick container packed quickly in one session in a dry environment. Looks fine when it leaves but over the next few days or weeks the canopy settles letting the bottom of the spring compress down wards pushing the cutter down away from the end of the loop creating a longer tail. If the pack job is not neat, folded rather then stuffed. If they do not take the time to compress/pre age the pack job as they close it. If the humidity is too low, there is actually a published range. If they try to close it fast rather then letting it settle over night before closing the last few flaps. All of these things can lead to the pack job settling and the pilot chute loosening. We used to just consider this to be the sign of sloppiness, an esthetic issue, at worst a risk of developing ring around the pilot chute. Now it's become clear that it is a real threat to functionality. It's very much a rigging question. So the real acid test is whether your pilot chute is down tight. Can you push on it? Does it wobble? Or does it fell as solid as a rock even after six months? If it ever stats to feel loose say after the weather changes and it gets humid. Take it back and have him replace the loop and tighten it.

What I've said here mostly refers to rigs with the cutter on a sub flap. If the cutter is above the pilot chute the tail become very consistent in length. The only problem is that the cutter isn't really happy there. Issues of routing, thickness, wear, appearance, and the possibility of damage to the cutter or wires argue against this placement. There have also been scares about the cutter pinching the loop and locking the container closed, think Argus.

The most extreme design is to have the cutter on the base plate. Javelin does this. You would think this was a horrible idea But it actually seems to work well for them. A lot of this is a product of the design of there rig/freebag/and base plate. With the molar bag and relatively small base plate they wind up with a relatively short loop regardless of the size of container or canopy. It's like the pate suckes up into the pack job and the PC sucks down. The tail can wind up being shorter then a badly packed Mirage. And it's going through only two pullies rather then four like a "normal" rig. So even with a relatively wimpy pilot chute spring the container still performs well.

The biggest wild cards are the pop tops. In theory their performance is not hindered by cutting the loop. In theory the deployment sequence is exactly the same. But they do still suffer from the pinching issue. Let's say you have a two pin like a racer. If one cutter pinches rather then cutting cleanly even just slightly what happens? So one loop is pinched. That means the other side of the cap henges up and the bottom of the pilot chute flips out and the thing just sets there flopping on it's side like a fish on your back held be that loop there is nothing trying to pull is loose. A single pin would have a 40 lb spring trying to break those final fibers of the loop but not with a two pin. You know I wonder how often this really happens. some people say that they need a certain amout of force on there loops for them to cut cleanly. Ever pulled the ripcord slowly on a strong seat pack so one clears before the other? Some thing like this happened to a guy at Dallas many moons ago. It wasn't an AAD thing. It was just bad rigging. Probably a bit of fabric caught in the top loop. Pulled his reserve and nothing happened. He looked over his shoulder and saw white flapping got a hold of the pilot chute and pulled it loose with a tug and through it out. I'm not sure if he had time to unstow his breaks or not. Point is that some thing similar could happen with a cutter.

You can tell I'm board. The point is that there are real problems that people are struggling with when it comes to loop cutting AAD's. Right now there really isn't a performance standard for them. I still remember the performance of the FXC 1200 that I jumped as a student. It was what it was. It's an AAD. We accepted it. No one expected greater accuracy from it. And you know where we set it 1200 ft. You planed your opening altitudes accordingly. Now these spoiled little bitches are whining about there cypresses as if they weren't the most impressive thing since sliced bread. They seem to feel that they should be magic and infallible. There has even been the suggestion that if they are less then perfect and fail to meet if not exceed the performance of the base system then they in some way make the rig unairworthy. The only way in which they could make the rig unairworthy is if they in some way prevented it from working as designed. In other word prevented the rig from deploying when you pulled the rip cord your self.

Lee


nigel99  (D 1)

Sep 2, 2013, 11:09 PM
Post #14 of 169 (10712 views)
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Re: [RiggerLee] Cutting the loop or pulling the pin? [In reply to] Can't Post

Thanks Lee,

From what you are saying, it is important to leave 'modern' gear to settle for as long as possible prior to closing the loop? Everything you've said makes sense and clarifies some of what was alluded to in previous threads.

It always amazes me how 2 or 3mm can sometimes be the difference between life and death (not specific to closing loops, but in general).


RiggerLee

Sep 3, 2013, 1:22 AM
Post #15 of 169 (10618 views)
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Re: [nigel99] Cutting the loop or pulling the pin? [In reply to] Can't Post

To be clear these are just a few packing techniques. People do this in different ways. In the end all that matters is that the pilot chute not loosen over time. I'll give you some examples. Most of them involve closeing the rig part way and the in one way or another encouraging the pack job to compress, settle, age before closing the rest of the flaps. This can allow you to close the rig with a much shorter loop then you would normally be able to and prevent it from loosening over time with out creating an excessively high pull force. Every one has there own tricks. I know one guy that closes the fist two flaps and the pilot chute then puts the rig under the cussion of his couch and eats dinner, watches movies, etc. while he sits on it. He's... kind of big, actually he's fucking fat so it works well for him. Some people like to use a bowling ball and leave it setting in the pocket of the pilot chute over night to compress the rig. Walking on the rig and using there feet and weight. I like to put it flat on the floor in the corner of a door frame and put my back against the other side. This lets me hold the frame and use the mussels of my legs over my weight to walk on it and compress it as I use my feet to... shape it. I'm kind of a small guy. Any time I have the chance I try to let it stand over night after I close the pilot chute before I finish closing the rig. The flip side of this is that it sucks to stop in the middle of things. In truth it's not the best rigging practice. It's easy to loose track of where you are in the packing and it's a good way to make mistakes. Particularly if you are working on more then one thing at a time. But letting it settle over night really helps the pack job to compress and lets you close the last 4 flaps the next day with a shorter tighter loop. All of these things is the equivalent of retightening the loop after the rig has been packed for a few weeks. You're just artificially accelerating the process. If you do this right the rig should not be a hard pull. The key is not forcing it. If you tried to just close it straight through you would have to force it but with technique and patience it should not be hard to close.

Lee


koppel  (F License)

Sep 3, 2013, 2:31 AM
Post #16 of 169 (10585 views)
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Re: [RiggerLee] Cutting the loop or pulling the pin? [In reply to] Can't Post

Great reading. Thanks


hackish  (No License)

Sep 4, 2013, 5:39 PM
Post #17 of 169 (10161 views)
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Re: Cutting the loop or pulling the pin? [In reply to] Can't Post

2 things:
a) About those ears. A number of the manuals say you can just ram them in or neatly fold them. I've always preferred using neat folds and the closing loop length is decidedly shorter than that used by a local rigger who frequently has a bad case of the wrinkles.

b) About the chance of lockup, one point many people forget about is closing loop lubrication. It says that you are supposed to lube up with the cypres silicone. Maybe I like my loops too juicy but many times I feel that other riggers entirely neglected this step or if they did it was only a little dab on the tip of the loop.

Added bonus, I also find that putting silicone on your closing loop makes it easier to pass through the cutter.

-Michael


RiggerLee

Sep 4, 2013, 6:39 PM
Post #18 of 169 (10099 views)
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Re: [hackish] Cutting the loop or pulling the pin? [In reply to] Can't Post

They came up with that lube, "snot", to make the loop more slippery so the tail can turn the corners around all those "pullies" easier. Great idea. But have you ever noticed how stiff those loops can get after they've been packed under the pull of a stiff pilot chute for months. I think it's mostly the tension but heat cycles might also play a part. Some times I wonder if we might be better off with a dry loop. It's like over time the silocone soaks into the yarn between the tiny fibers by capulary action, as the fibers of the loop are squeezed together over time by the tension it's almost like they bond. They don't want to shift relative to each other thanks to the surface tension of the siocone. It's like the loop is slick but stiff after a few months. Don't get me wrong, I'm still a liberal user of Snot. At the moment it seems to be our best bet but I wonder if there might be a better lubricant out there or if we might actually be better off with a dry loop.

A lot of small changes have been made over the years and a real effort has been made to go back and reevaluate the rigs in terms of pilot chute launch by cutter. I remember lissening to a conversation about it at a PIA where they were discussing possible standards for this testing but I was not clear if there was going to be any ageing in the test. If the rigs were getting poped as soon as they were packed it might explane why we are seeing hesitations in the field.

Lee


JohnSherman  (D 2105)

Sep 9, 2013, 8:05 AM
Post #19 of 169 (9612 views)
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Re: [RiggerLee] Cutting the loop or pulling the pin? [In reply to] Can't Post

Do not lubricate any Racer loops!


IanHarrop  (C 1152)

Nov 28, 2013, 9:54 AM
Post #20 of 169 (8654 views)
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Re: [nigel99] Cutting the loop or pulling the pin? [In reply to] Can't Post

Interesting teaser on the Parachute Labs FB page...

According to their FB page "Coming soon, all Racers will come with our brand new Automatic Ripcord activation device."

Eliminating the cutter is an interesting idea. There will be some questions which might include...
- it looks like it includes a ripcord stop and those fell out of favour a long time ago
- will it work with existing AADs.
- will other rig makers will be willing to licence it.

Bet there are lots more questions Cool

https://www.youtube.com/watch?v=N4LgO6Irk5k


(This post was edited by IanHarrop on Nov 28, 2013, 9:55 AM)


dirtbox  (D 31759)

Nov 28, 2013, 10:11 AM
Post #21 of 169 (8595 views)
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Re: [IanHarrop] Cutting the loop or pulling the pin? [In reply to] Can't Post

pneumatic computerized FXC??? I don't see a stopper so much as that is the limit of the range of motion of the device perhaps? I know a dz in On that would love this ...Angelic


JerryBaumchen  (D 1543)

Nov 28, 2013, 11:15 AM
Post #22 of 169 (8502 views)
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Re: [IanHarrop] Cutting the loop or pulling the pin? [In reply to] Can't Post

Hi Ian,

He does say this:

We are putting them on Racers as we speak.

We are also installing one on Karels Javlin and video will be posted.


It will be interesting,

JerryBaumchen


JohnSherman  (D 2105)

Nov 28, 2013, 11:46 AM
Post #23 of 169 (8452 views)
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Re: [JerryBaumchen] Cutting the loop or pulling the pin? [In reply to] Can't Post

Let clear/muddy the water a bit.Smile

I can not speak for PLI. I can only relay what I know about the technical questions.
It has been tested and operationally interfaces correctly with CYPRES Vigil & Argus. They will recgonize this device as a cutter and accept it or reject it during POST as it would a cutter. The device is not compressed air fired. It is fired with a gas generating squib just like a cutter.
The demo is done with a CO2 Bicycle inflator. I can get 8 or 9 firings with the CO2 and only one with the Squib. The Squib generates more force than the CO2 so this makes the CO2 a great test as well as a demo tool.
The mechanical connection to the 3 AADs referenced is a different matter. The IOpener, as it is called, comes with a 3.5MM stereo phone jack which is manufactured to be plug and play with the Vigil. The CYPRES and the Argus require adaptor pigtails of which there is a small supply.
Yes, other manufacturers have been offered this and I understand several are planning to incorporate it. PLI is just the first to accept it and make the announcement/teaser on their Facebook page.
Installation is as simply a reserve ripcord housing replacement.
No cable stop!
The handle and cable come completely out of the housing on full extension. Video to come soon.

I will try to answer technical here as requested.
In my mind there is no question when considering the Thread question. The history of cutters is long and bloody.
This device, unlike cutters, does not and will not interfere with the normal operation of your certificated reserve. This is an FAA rule and cutters violate it. PIA through its release of TS-112 tacitly acknowledges this.


Premier skydiverek  (C 41769)

Nov 28, 2013, 11:57 AM
Post #24 of 169 (8429 views)
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Re: [JohnSherman] Cutting the loop or pulling the pin? [In reply to] Can't Post

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"?


JohnSherman  (D 2105)

Nov 28, 2013, 12:23 PM
Post #25 of 169 (8381 views)
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Re: [skydiverek] Cutting the loop or pulling the pin? [In reply to] Can't Post

Quote:
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"?

How much is the pin bent? We have built a force generation tester which measures the pull force of the ripcord. Currently we have seen a low of 80 pounds and a high of 120 pounds. This is more than I can pull. I will post "Burn curves" in the future when we have finalized the Squib formula. We are at an operational state at this time but we want to hone the formula and tighten the spec. This process will take no more than 2 days when we get the necessary Pyrogin.


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