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MakeItHappen 15
QuoteFor instance, if the problems we have experienced are related to the angle of the closing loop through the cutter,....
Yeah, that may be the issue for the Argus.
A simple solution is to place a cap on the end of the cutter that has 'arms' with retaining hoops that effectively narrows the portal that the loop passes through. It would at least keep the angle to a certain angle, but not necessarily perpendicular.
This would make packing a bit more tricky, but it would address the 'angle' issue, if that is really the issue involved.
If the cutter placement was such that you did not need a pullupcord to thread the closing loop through the cutter, then the packing issue is not that big of a deal. You could also place a spring under the cap so that the hoop opening could be enlarged for packing and then the spring narrows it down once the closing loop is threaded.
Or you could redesign the cutter such that the portal for the closing loop is smaller.
My thinking is that since the Vigil, that also has a cylindrical cutter, and a recess anvil and the Argus type failures have not appeared with the Vigils, is that the tolerances between the OD of the cutter cylinder and the ID of the recessed anvil are different between Argus & Vigil and that the distance is larger on the Argus than on the Vigil. Since the specs of these cutters are proprietary we may never know.
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Make It Happen
Parachute History
DiveMaker
Make It Happen
Parachute History
DiveMaker
QuoteQuoteFor instance, if the problems we have experienced are related to the angle of the closing loop through the cutter,....
Yeah, that may be the issue for the Argus.
A simple solution is to place a cap on the end of the cutter that has 'arms' with retaining hoops that effectively narrows the portal that the loop passes through. It would at least keep the angle to a certain angle, but not necessarily perpendicular.
This would make packing a bit more tricky, but it would address the 'angle' issue, if that is really the issue involved.
If the cutter placement was such that you did not need a pullcord to thread the closing loop through the cutter, then the packing issue is not that big of a deal. You could also place a spring under the cap so that the hoop opening could be enlarged for packing and then the spring narrows it down once the closing loop is threaded.
Or you could redesign the cutter such that the portal for the closing loop is smaller.
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I was not trying to address the Argus issue at all.
My point was only that the cutter location that works best for one rig might not work best for a rig of a different design.
gowlerk 2,190
Ok, then. Obviously it's time to go back to the future. All that has once been will be once again. We need a pyrotechnic pin puller. One that could not interfere with the normal operation of the ripcord in any way. Although I'm sure it has already been explored and rejected.
All I know for sure is that an AAD with a potential failure mode like a trapped reserve is not acceptable.
Ken
All I know for sure is that an AAD with a potential failure mode like a trapped reserve is not acceptable.
Ken
Always remember the brave children who died defending your right to bear arms. Freedom is not free.
QuoteWe need a pyrotechnic pin puller. One that could not interfere with the normal operation of the ripcord in any way.
AFIAK cutters were introduced, because there could be some interference with pin and pin pullers.
An AAD with a cutter might save your life if you have a bent reserve pin.
BrianM 1
QuoteAll I know for sure is that
an AADa container with a potential failure mode like a trapped reserve is not acceptable.
Fixed it for you, since that's a potential failure mode of any cutter mounted above the pilot chute.
"It's amazing what you can learn while you're not talking." - Skydivesg
billvon 2,990
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>We need a pyrotechnic pin puller.
And then if the swage breaks you're going in - and not even an AAD will save you, whereas a loop cutter will.
There's no perfect answer.
And then if the swage breaks you're going in - and not even an AAD will save you, whereas a loop cutter will.
There's no perfect answer.
QuoteOk, then. Obviously it's time to go back to the future. All that has once been will be once again. We need a pyrotechnic pin puller. One that could not interfere with the normal operation of the ripcord in any way. Although I'm sure it has already been explored and rejected.
All I know for sure is that an AAD with a potential failure mode like a trapped reserve is not acceptable.
Ken
But a rig with such a failure is okay?
The original reason for moving cutters above pilot chutes was not an AAD problem.
It was a RIG problem, that cutting the loop "deeper in the rig" left a long tail that could lock the rig.
The AAD did exactly what it was intended to do - it cut the loop.
Anybody who is building rigs today must concede that AADs are here to stay.
Since putting the cutter so near the pin can cause new problems, like a cutter jamming on a loop, it follows that a rig manufacturer had better build a rig that will open when you cut the loop far from the pin, leaving that troublesome "tail".
There are a variety of rigs that tolerate the long tail without problem.
Perhaps all rigs should be able to make that claim.
gowlerk 2,190
QuoteBut a rig with such a failure is okay?
The original reason for moving cutters above pilot chutes was not an AAD problem.
I could not disagree with this idea more. An AAD is an accessory. It does not require a TSO, and it is not necessary.
Ken
Always remember the brave children who died defending your right to bear arms. Freedom is not free.
QuoteQuoteBut a rig with such a failure is okay?
The original reason for moving cutters above pilot chutes was not an AAD problem.
I could not disagree with this idea more. An AAD is an accessory. It does not require a TSO, and it is not necessary.
Ken
What idea are you disagreeing with?
From what you quoted, are you saying that the cutter was moved because the AAD was faulty?
By moving the cutter, the manufacturer tacitly admitted that their rig did not work correctly when the cutter was where they first put it. The cutter location was not chosen by the AAD manufacturer. It came from the rig manufacturer.
They are already reacting to the idea that they won't sell any rigs if they don't admit that AADs are here to stay.
And what does any of this have to do with the idea of a TSO for AADs?
Of course an AAD is an accessory, except, of course, for where it is required.
But the manufacturer would soon be out of business if he said, "oh, by the way, you can't use an AAD with this rig."
So admitting that they are here to stay is required.
gowlerk 2,190
QuoteWhat idea are you disagreeing with?
Sorry, I did not quote the correct part of your post.
I am disagreeing with the concept that a rig can be considered faulty because a given AAD may not function properly on it. The tail does not wag the dog. The problem here is not long loop/loose loop/silicon or no silicon. The problem here is a cutter that sometimes fails to cut. Everything else is interesting discussion material, but beside the point. There is no talk of grounding AADs with proven cutters, only the ones that have been shown to occasionally fail to cut the loop cleanly. Without this clearly unforeseen flaw, there would be no discussion here.
Ken
Always remember the brave children who died defending your right to bear arms. Freedom is not free.
QuoteWhat idea are you disagreeing with?
QuoteSorry, I did not quote the correct part of your post.
I am disagreeing with the concept that a rig can be considered faulty because a given AAD may not function properly on it.
I didn't see where he said that. What he said was:
"The original reason for moving cutters above pilot chutes was not an AAD problem.
It was a RIG problem, that cutting the loop "deeper in the rig" left a long tail that could lock the rig.
The AAD did exactly what it was intended to do - it cut the loop. "
If, after the cutting of the closing loop, the rig doesn't allow the reserve to extract because of a trapped (and already cut) closing loop, then yes...it's a rig/container problem, IMO.
Now having said that, yes, a screwed up or broken reserve PC with no spring power may be a different animal.
My reality and yours are quite different.
I think we're all Bozos on this bus.
Falcon5232, SCS8170, SCSA353, POPS9398, DS239
I think we're all Bozos on this bus.
Falcon5232, SCS8170, SCSA353, POPS9398, DS239
QuoteQuoteWhat idea are you disagreeing with?
Sorry, I did not quote the correct part of your post.
I am disagreeing with the concept that a rig can be considered faulty because a given AAD may not function properly on it. The tail does not wag the dog. The problem here is not long loop/loose loop/silicon or no silicon. The problem here is a cutter that sometimes fails to cut. Everything else is interesting discussion material, but beside the point. There is no talk of grounding AADs with proven cutters, only the ones that have been shown to occasionally fail to cut the loop cleanly. Without this clearly unforeseen flaw, there would be no discussion here.
Ken
This discussion was about how/why the cutter locations were chosen. It was not about the failed cutters, per se. It was about where a cutter should be to have minimal negative impact on the function of the rig, regardless of what might go wrong with the cutter.
Anyway...
The cutter was moved long before we had any thoughts of a cutter jamming on a loop.
The manufacturer chose the original cutter location.
The manufacturer decided to change the location after some people found that the rig could lock up.
There was a video. IIRC it came from Canada. The video showed that a fully cut loop with a long tail could jam the rig.
The cutter location change came shortly after that video. (IIRC).
Since the manufacturer chose both the original location, and the new location, and there was no consideration of a failed cutter at that time, I must conclude that the manufacturer decided for himself that the rig needed to change, because it was not working the way he had intended.
Of course, none of this says anything about the failed cutters. That is an extremely serious problem that MUST BE FIXED. But it is a different problem from what we have been talking about here.
bofh 0
QuoteI think all cutters are EXPECTED to do their job...QuoteThe CYPRES cutter is expected to do its job even if all the errors you mentioned are made, ie it will cut the loop.
No, not in the presence of the the different errors that were mentioned in the post I was replying to.
QuoteQuoteI think all cutters are EXPECTED to do their job...QuoteThe CYPRES cutter is expected to do its job even if all the errors you mentioned are made, ie it will cut the loop.
No, not in the presence of the the different errors that were mentioned in the post I was replying to.
Yes, even then, AADs are expected to do their job.
The affected AADs have been around a while. Those "errors" didn't just recently appear on the scene.
Incomplete cuts have only recently become an major issue with them.
The AADs were expected to do their job before and they are still expected to do the job today.
The AADs are not meeting those expectations, hence, the backlash.
What you are calling errors are not really errors. They are conditions that all AADs face every day and there's no way, right now, to prevent those things from happening. It's a mistake to blame recent cutter incidents on riggers and closing loops as some manufacturers would have you believe.
My reality and yours are quite different.
I think we're all Bozos on this bus.
Falcon5232, SCS8170, SCSA353, POPS9398, DS239
I think we're all Bozos on this bus.
Falcon5232, SCS8170, SCSA353, POPS9398, DS239
No matter what brand of AAD you have, with the reserve pin on top you always have an extra risk if you put the cutter on top. even if this risk is very small. It's electronics and nobody can say that it's full proof and 100% safe.
I never understood the descision the move the cutter on top. (I now why they did it but never understood that descision)
I never understood the descision the move the cutter on top. (I now why they did it but never understood that descision)
QuoteNo matter what brand of AAD you have, with the reserve pin on top you always have an extra risk if you put the cutter on top. even if this risk is very small.
What risk is it that you would always have if you put the cutter on top? Would that risk be present if the AAD was mounted elsewhere?
QuoteIt's electronics and nobody can say that it's full proof and 100% safe.
...and yes, that applies regardless of mounting location.
My reality and yours are quite different.
I think we're all Bozos on this bus.
Falcon5232, SCS8170, SCSA353, POPS9398, DS239
I think we're all Bozos on this bus.
Falcon5232, SCS8170, SCSA353, POPS9398, DS239
ufk22 33
QuoteNo matter what brand of AAD you have, with the reserve pin on top you always have an extra risk if you put the cutter on top. even if this risk is very small. It's electronics and nobody can say that it's full proof and 100% safe.
I never understood the descision the move the cutter on top. (I now why they did it but never understood that decision)
You also have an extra risk if you put the cutter on the bottom.
Bottom line, if Argus had a more reliable cutter we wouldn't be having this discussion.
This is the paradox of skydiving. We do something very dangerous, expose ourselves to a totally unnecesary risk, and then spend our time trying to make it safer.
sundevil777 102
QuoteQuoteQuoteQuoteQuotehis means it is NEVER acceptable to place the cutter in a location that could render the system inoperable if there is a cutter failure. Period.
what are racer/reflex users supposed to do then?
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Racer and Reflex users are expected to continue with the factory-recommended packing procedures, loop length, etc.
We have not heard of any Racers or Reflexes - with AADs - failing to open when needed. Any time you change one variable, you mess with a dozen other variables, and it will take you years to figure out all the new malfunction modes.
Don't mess with success.
Sounds like you advocate having the cutter as close as possible to the pin. Is that what you're saying?
I don't think he was suggesting that a particular location is best in all cases.
All he said was that in the cases of the Racer and Reflex, the current location seems to be working. (But maybe these rigs don't have enough "exposure", and so the statistical validity of our experiences might also be questioned.)
Not all "nearest the pin as possible" locations are the same.
For instance, if the problems we have experienced are related to the angle of the closing loop through the cutter, then placing the cutter on a flap near the pin might be bad, but putting it on the backpad near the pin might be perfect. (Contrasting Mirage and Racer, for example.)
Similarly, on the backpad near the closing loop anchor point might be great in a rig where the length of the "tail" is not a problem, while the same location in a rig that is sensitive to the length of the "tail" would not be good.
Rigs are different and so are cutters. What works best for one rig and a particular cutter might not work best on another rig with a different cutter.
Hard and fast rules are tough to come by in discussions like this.
Isn't it true that a rig with the pins against your back will be vulnerable to a cutter locking the loop, not allowing a ripcord to function, no matter where the cutter is placed?
Some think that rigs should not allow such a scenario to exist.
As you said, placement of a cutter against your back might have a better setup to prevent a locked loop because the closing loop path might be 'straighter' as it goes through the cutter, assuming that problems with the Argus cutter locking are in fact related to the angle of the loop as has been speculated.
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
Deimian 43
Sorry for resurrecting a death thread 
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I am thinking in which rig should I get next. The one that I'm currently thinking of has the cutter in one of the closing flaps. It bothers me a bit, but not too much. My rationale is that if the cutter fails for whatever reason, and pinches the loop, I am already pretty much death, because below activation altitude I wouldn't have time to pull the ripcord myself. The amount of errors/failures that would stack up for that to happen (no manual ripcord pulling, no RSL activation, and cutter failure) is, from the probabilistic point of view, close enough to 0 to be comfortable with the trade off offered by the top location of the cutter. I don't like it, but I doubt that it will contribute significantly to a negative outcome. At best, if that happens, you would speculate if pulling the ripcord after activation altitude could have give me a small chance 
.
The rig I am considering has fully enclosed RPC, and a wide (close to the yoke) top flap (which I guess can make the extraction of the freebag a bit more difficult, but it is difficult to say without manually exploring the reserve tray), so I am more concerned about letting the RPC out as fast as possible.
Now, after explaining my rationale, just to see if somebody has any input to it, I have a question unrelated to my thinking, but related to the thread . Why not using double cutters? One on the closing flaps and another in the bottom? This way there are 4 possible scenarios:
-Both cutters work: Awesome, the closing loop do not have to zigzag as much as in the bottom placement, so it effectively works as pulling the pin. In other words, better than a single bottom cutter.
-Bottom cutter fails, top cutter works: Scary, one cutter failed, but the other did, and again with optimal performance, as the loop doesn't zigzag. In other words, better than a single bottom cutter.
-Top cutter fails, bottom cutter works: Scary, pulling the ripcord wouldn't release the RPC, but the bottom cutter might save the day, with a bit of delay because the loop has to zigzag between the grommets. In other words, better than a single top cutter.
-Both cutter fail: Well, fuck. In other words: worse than a bottom cutter because it effectively prevent you from saving your own life, but chances of successful manual activation below automatic activation are pretty damn slim anyway.
I can see why some manufacturers that opts for the bottom cutter wouldn't want this double cutter. But I don't see why a manufacturer that opts for the top cutter wouldn't want this double cutter. There is no downside to it, besides the increased price of the AAD.
Any thoughts on that?
BTW: I'll probably change rigs far in the future, I think I can downsize again in my current rig. Does somebody know how a 135 canopy fit in a Wings W11?
df8m1 24
DeimianSorry for resurrecting a death thread
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Why not using double cutters? One on the closing flaps and another in the bottom? T
-Both cutters work: Awesome, the closing loop do not have to zigzag as much as in the bottom placement, so it effectively works as pulling the pin. In other words, better than a single bottom cutter.
-Bottom cutter fails, top cutter works: Scary, one cutter failed, but the other did, and again with optimal performance, as the loop doesn't zigzag. In other words, better than a single bottom cutter.
Any thoughts on that?
From what I gather, the reason you are thinking about using redundant cutters, but each in different locations (upper and lower), is primarily because of a lack of confidence in the cutter's ability to cut the loop.
If the cutters are shady, then adding more in an effort to increase the likely hood of reserve pack opening would make sense if you were stuck on the island with only one type of cutter, but, that is not the case.
Don't forget that the reason that some container manufacturers moved the cutter location to some where above the PC is because there were totals due to long loops. IMOP, the current reserve containers are not designed to be opened from the inside (as a cutter does), and some manufacturer's designs and construction methods are more forgiving than others. SO, with some rigs there would be a combined potential for both a top pinching cutter and a long loop total, where the long loop total trumps the lower cutter that did cut the loop as in one of the scenarios you mentioned.
The thought that if both cutters cut the loop (at both ends) could allow faster PC launch is something I have not heard before, so kudos for that, but, I’m not sure that would be so. One way to find out though.
The best combination would be a cutter that will cut the loop cleanly (without requiring any loop tension in order to do so), and a reserve container that was designed to be opened from with in as a primary method of opening, as apposed to an after thought.
Aside from the container and cutter reliability issues, adding an additional cutter increase the amount of power needed to fire both of them, so there is a measurable required advantage with a single cutter over a dual cutter. Plus, depending on how the AAD’s firing circuit is designed, it is possible to have one cutter shorted, which would not show up on a self test, but would most likely result in the other good cutter not firing because all the power took the path of lest resistance and went through the short instead of the initiator of the other cutter. Granted, a single cutter circuit could be shorted just the same, and would pass a self test, but you were asking about any disadvantages of having two cutters, and although the results would be the same, (a short causing a no fire), any potential advantage from a second cutter would be eliminated given that scenario due to the design of the AAD.
You are thinking and that is good, and this is just my thoughts that come to mind as I type. I like to say “there is one way to find out who is right”, try it and see what happens, maybe something totally unexpected will happen.
mxk 1
DeimianMy rationale is that if the cutter fails for whatever reason, and pinches the loop, I am already pretty much death, because below activation altitude I wouldn't have time to pull the ripcord myself.
Pulling the ripcord wouldn't help you anyway. The pilot chute may launch, but the free bag with your reserve will still be held in place by the cutter and flap 1 (or whichever flap it's attached to).
DeimianBut I don't see why a manufacturer that opts for the top cutter wouldn't want this double cutter. There is no downside to it, besides the increased price of the AAD.
Take a piece of CYPRES cord, pull it tight, and cut it with scissors. Works well, right? Well... depending on the quality of the scissors. Now, release all tension and try to cut it again.
If you have two cutters, they are not going to be perfectly synchronized. One will cut first. If that happens to be the bottom cutter, the top one is now trying to cut a loop without any tension on it, increasing the chances of it pinching the loop and keeping the container closed. That's a pretty big downside, not to mention the extra complexity in the design.
Deimian 43
mxk
Pulling the ripcord wouldn't help you anyway. The pilot chute may launch, but the free bag with your reserve will still be held in place by the cutter and flap 1 (or whichever flap it's attached to).
That's what I meant. With a cutter failure I'd die because it would prevent me from opening the container, but that that fact wouldn't matter, as I would be too low anyway.
mxk
Take a piece of CYPRES cord, pull it tight, and cut it with scissors. Works well, right? Well... depending on the quality of the scissors. Now, release all tension and try to cut it again.
If you have two cutters, they are not going to be perfectly synchronized. One will cut first. If that happens to be the bottom cutter, the top one is now trying to cut a loop without any tension on it, increasing the chances of it pinching the loop and keeping the container closed. That's a pretty big downside, not to mention the extra complexity in the design.
The comment about cord tension makes a good point, I didn't think about it, but I am not sure it is true. There are plenty of videos around of AAD cutters cutting Cypres cord without tension on it. If the cutter is working as designed, that shouldn't be an issue. But even if it was, if the top cutter pinches the closing loop, the bottom of it is not attached to the container anymore (because it has been cut by the bottom cutter), so it should open anyway.
I don't think he was suggesting that a particular location is best in all cases.
All he said was that in the cases of the Racer and Reflex, the current location seems to be working. (But maybe these rigs don't have enough "exposure", and so the statistical validity of our experiences might also be questioned.)
Not all "nearest the pin as possible" locations are the same.
For instance, if the problems we have experienced are related to the angle of the closing loop through the cutter, then placing the cutter on a flap near the pin might be bad, but putting it on the backpad near the pin might be perfect. (Contrasting Mirage and Racer, for example.)
Similarly, on the backpad near the closing loop anchor point might be great in a rig where the length of the "tail" is not a problem, while the same location in a rig that is sensitive to the length of the "tail" would not be good.
Rigs are different and so are cutters. What works best for one rig and a particular cutter might not work best on another rig with a different cutter.
Hard and fast rules are tough to come by in discussions like this.
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