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sfzombie13

installing a drogue system on a sport rig

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is it legal to modify the pilot chute part of the main canopy container so that it uses a drogue system?  in my opinion, this is the best way to prevent a hard opening from killing you, and i have an old container lying around.  from my limited understanding it is not, since it involves changing the function of the container, but the reserve part of the container is covered under the faa jurisdiction and not the main part.  i also recall being told years ago that i could even make my own canopy but that only i could jump it, but that could have been false, mis-remembered, or changed. 

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I think you are asking if you need to ask permission to do make the change.  That depends on how you interpret "parachute" in Part 65.125(c):

Quote

A certificated parachute rigger need not comply with 65.127 through 63.133 (relating to facilities, equipment, performance standards, records, recent experience, and seal) in packing, maintaining, or altering (if authorized) the main parachute of a dual parachute pack to be used for intentional jumping.

 

If you think "main parachute" means all the stuff that goes with it, including main container, bag, pilot chute, etc., then you don't need permission (my preferred take on the meaning of the regulation).  If you think "main parachute" means just the canopy, then you're stuck with asking the manufacturer or your local FSDO and you might as well abandon your project.

BTW, Strong Enterprises made a drogue-equipped student rig several years ago, but it never caught on.

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12 hours ago, mark said:

I think you are asking if you need to ask permission to do make the change.  That depends on how you interpret "parachute" in Part 65.125(c):

If you think "main parachute" means all the stuff that goes with it, including main container, bag, pilot chute, etc., then you don't need permission (my preferred take on the meaning of the regulation).  If you think "main parachute" means just the canopy, then you're stuck with asking the manufacturer or your local FSDO and you might as well abandon your project.

BTW, Strong Enterprises made a drogue-equipped student rig several years ago, but it never caught on.

that is what prompted the question, it is a touch confusing and i will probably do it anyway.  thanx for the info on strong doing it on a student rig.  now it seems i just have to find out if it never caught on due to preference or a bad design/safety issue or something like that. 

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14 hours ago, sfzombie13 said:

in my opinion, this is the best way to prevent a hard opening from killing you,

 

 

14 hours ago, sfzombie13 said:

modify the pilot chute part of the main canopy container so that it uses a drogue system?

On a tandem, the drogue system introduces most of the tandem specific malfunction modes that need careful training and planning to prevent. And I can see no way that it could prevent hard openings. How on Earth did you come to this opinion?

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26 minutes ago, gowlerk said:

On a tandem, the drogue system introduces most of the tandem specific malfunction modes that need careful training and planning to prevent.

Strongly, STRONGLY agree with this ^^^

Be careful that you aren't creating more problems than you are trying to solve...

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1 hour ago, gowlerk said:

 

 

On a tandem, the drogue system introduces most of the tandem specific malfunction modes that need careful training and planning to prevent. And I can see no way that it could prevent hard openings. How on Earth did you come to this opinion?

physics.  or math.  if the deployment at 120 mph creates enough g force to kill you, then an opening at 75 mph MAY reduce the g force enough to keep you alive.  maybe not.  i am not an engineer and do not have the necessary knowledge to work out the math yet.  that is step whatever after i follow the advice i was given after i talked to chuck at strong enterprises about the student drogue they used at one time and the reason it was taken out of service.  he also mentioned that i need to use the whole drogue system and not just the handles, something i had not considered, in order to be able to release the drogue properly to avoid a line dump, thus creating the very thing i am trying to prevent.  he also suggested some additional research material to look into. 

all of this is taking a backseat to my current project, an impact rated skydiving helmet with a built in case for a gopro, no snag points and no external mounts.  as soon as the 3d printer comes in, i can start working with the carbon fiber and get a prototype in the air, maybe as soon as this month.

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23 minutes ago, sfzombie13 said:

if the deployment at 120 mph creates enough g force to kill you, then an opening at 75 mph MAY reduce the g force enough to keep you alive.  maybe not. 

Keep in mind that it would take at least 1000 feet and possibly more for a large pilot chute to slow you down that much. I like your helmet plans much more!

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9 minutes ago, gowlerk said:

Keep in mind that it would take at least 1000 feet and possibly more for a large pilot chute to slow you down that much. I like your helmet plans much more!

i'll keep you updated on the helmet.  it will be done first anyway.  the other idea is one that may never materialize, depending on what i find out in my research.  it is a rather small subset of jumpers who would even consider using it, and it would greatly modify your deployment and emergency procedures, possibly to the point of introducing some element of danger that is unacceptable.  that is how all great ideas come about though, they have to be thought of first.  this may, or may not be, one of them.  we shall see.

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Hard openings just weren't as hard back for the "modern" canopies I used back in the 90s. I think dacron lines has a part in it (see other thread of mine about that more specifically) and I suspect that some explosive openings might be due to the locking stows breaking prematurely. Those locking stows are subjected to their max stress right at the time it matters most (of course), so I advocate locking stows that are stronger than just a rubber band - whether it is tube stows, silly stows/rings/whatever.  Have you ever found a locking stow broken when packing - ask yourself if it might have broken before line stretch, not a comforting feeling. We deserve something for the locking stows that is designed to not break.

I recognize the argument of a rubber band breaking for a bag-lock malfunction, but for my 2 center locking stows prefer the additional protection against what I see as the primary mode for fabric to be dumped into the air early.  Since I first heard about tube stows, probably late 80s, I've used some type including making a lot of them. Never a problem.

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On 8/11/2020 at 3:50 PM, mark said:

.....

BTW, Strong Enterprises made a drogue-equipped student rig several years ago, but it never caught on.

It caught on the reserve, preventing the reserve from opening.

Back around 1990, Ted Strong was trying to develop a new training program that started with tandem jumps, then progressed to droque-stabliized solo freefall, so he installed a drogue on Strong Combination Student container. The drogue was based upon a far more complex design that originated with Soviet Air Force ejection seats, was simplified for Soviet para-troopers, was dumbed down for Russian smoke-jumpers, then dumbed down again for civilian tandems.

The solo drogue system worked okay until a student went into a violent spin - in freefall - over Hinckley, Illlinois. When the FXC got scared, it pulled the reserve ripcord, but the round reserve wrapped around the drogue and never opened. End of that idea! 

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the guy i talked to at strong said they also had problems with the students relying on the drogue rather than arching, so it wasn't really good for them although it did what they wanted, other than the reserve entanglement you mentioned.  that will definitely be one of the test scenarios if i ever make it that far, thanx a lot for that very valuable info.

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You probably already thought of this but I don't see it mentioned.
Due to drogue pilot chute would probably be larger size, it would require a kill line (collapsability).  
It requires one extra step of gear prep and gear check which is not always good for students / new jumpers.
I personally use it, but there is for sure some jumpers who don't want that one extra thing to worry about.

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If you wanted to invent a drogue - to reduce opening shock - you need some sort of speed-sensitive link. ... maybe a drag-sensitive link.

Basically, if you toss your drogue/pilot-chute ate more than 130 miles-per-hour, it would remain firmly attached to the harness until you decellerate to slower than 100 mph. Then the drogue dis-connects from the harness and drags your main to line-stretch.

Engineers have devoted many millions of dollars to perfecting similar systems for ejection seats.

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On 8/14/2020 at 1:56 PM, riggerrob said:

If you wanted to invent a drogue - to reduce opening shock - you need some sort of speed-sensitive link. ... maybe a drag-sensitive link.

Basically, if you toss your drogue/pilot-chute ate more than 130 miles-per-hour, it would remain firmly attached to the harness until you decellerate to slower than 100 mph. Then the drogue dis-connects from the harness and drags your main to line-stretch.

Engineers have devoted many millions of dollars to perfecting similar systems for ejection seats.

i was looking to just commandeer the one the strong uses for their tandem rigs.  i don't have the facilities nor the training to develop something new.  if it now requires anyone using it to pull higher, then pull again to release the drogue.  i just need to figure out timing rather than try to devise a system to release it automatically. 

matja, thanx for the input regarding kill line pilot chutes, and when i was talking to the guy at strong, he did mention i would also need the pilot chute to have a release system.  that was the main reason for just putting the whole system in place, somebody has already done the r&d. 

reading the other thread regarding the break away risers and the climbing harness i doubt i will pursue something as complicated as this.  my son's mother passed last weekend and our world has been turned upside down.  if i can find those risers, i will send them off for the prototype to coolbeans.

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(edited)

You are going to create many additional problems on your quest to solve the hard opening problem.

Many others have mentioned this, but the malfunction decision tree is much more complicated for a tandem system because of the addition of the drogue. Additionally the drogue on a tandem is intended to be deployed early at the start of a tandem jump. On a tandem this keeps the pair from hitting tandem terminal, and also provides response time if there is an issue with the drogue deployment so the instructor can respond.

Your system will be deployed much closer to the hard deck, and would allow almost no time to respond to a drogue related issue. Drogue in tow at the bottom end of the skydive, you are screwed. Drogue entanglement at the bottom end of the skydive, you are screwed. I could continue but you get the point.

  

Edited by DougH

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20 hours ago, DougH said:

You are going to create many additional problems on your quest to solve the hard opening problem.

Many others have mentioned this, but the malfunction decision tree is much more complicated for a tandem system because of the addition of the drogue. Additionally the drogue on a tandem is intended to be deployed early at the start of a tandem jump. On a tandem this keeps the pair from hitting tandem terminal, and also provides response time if there is an issue with the drogue deployment so the instructor can respond.

Your system will be deployed much closer to the hard deck, and would allow almost no time to respond to a drogue related issue. Drogue in tow at the bottom end of the skydive, you are screwed. Drogue entanglement at the bottom end of the skydive, you are screwed. I could continue but you get the point.

  

i understand completely having talked to an affi at the dz.  i sincerely hope that coolbeans gets his riser prototype finished before i get around to this, as his idea will also save my life in the case of a hard opening and is much more likely not to introduce too many additional issues to the system.  i may introduce some sort of cutting device in the case of a drogue in tow, but that is just one more device that can fail.  mals will have to be dealt with though, thanx for the advice, i will use it.

riggerrob, thanx for that idea, it would be wise for testing purposes and i will take that advice when it comes time for tests.

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I suggest finding the thread about always keeping the slider "outside" of the rest of the canopy so it would in theory hit the wind reliably and early to keep it up against the stops, instead of allowing the slider to be shielded from the wind which could allow it to fall away from the stops, theoretically. He had a lot of successful jumps packing like that, a lot of people thought there must be some hidden unintended consequence...

 

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1 hour ago, Sam618 said:

Its not gonna help, pimp. The hardest opening I had was on a tandem jump, it exploded a whole cell and I had to cutaway. 

it may have helped had you not had another person strapped to you with the drogue out.  it still may have blew the cell, but you would have been going slower, thus you would have pulled less g's.  i'm not trying to prevent the hard openings, just trying to make them survivable.  i hear that old guys have torn aortas from them and am getting old.  i have yet to have a hard one and mostly fly larger canopies anyway but if i can save one life it would be worth it, especially if it were mine.  it may turn out impractical or a pain in the arse to use, in which case i would at least have tried.  i think the break away risers coolbeans is working on is better, but you're not supposed to put your eggs in one basket.

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17 hours ago, sfzombie13 said:

i have yet to have a hard one and mostly fly larger canopies anyway

From what I recall, normally the brutal openings happened with large canopies. I haven't seen or read about a brutal opening in a small one. Makes sense also, for 2 reasons I think.

 

1. Many large canopies have the same slider size than medium sized canopies. The storm for instance has the same slider all the way from 97 sqft to 230 sqft. Others make 2 sizes or styles (normal slider vs domed slider), making often the cut at 170 sqft. This is despite the fact that the distance between line groups is larger on big canopies. In other words, you have the same force pushing on the slider from bottom to top, but more force spreading the lines and therefore pushing the slider down, so the slider will come down quicker and potentially make the opening harder.

 

2. Large canopies have simply more surface, so they can cause more drag. That means larger deceleration on opening. On a windy day, holding a tiny canopy is easier than holding a massive one. Same thing on opening, a small canopy can slow you down just so much, but a big one will slow you down much more.

 

My point is that jumping larger canopies does not protect you from hard openings. If something, that's the opposite.

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45 minutes ago, Deimian said:

My point is that jumping larger canopies does not protect you from hard openings. If something, that's the opposite.

that is something that i had not considered.  it does make sense and i wonder if the issue is something that can be fixed by using a larger slider rather than break away risers or a drogue system.  do you know of any data on it?  it would be worth doing some investigation in any case.  thanx for that input.  i was planning on going from my 218 to the 181 sometime when it comes back from the shop.  looks like it may indeed save my life, even if it's not a reserve any longer.

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