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chrischan1985

why not a second reserve?

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Hi all, I am new to skydiving and this might be a silly question..

Why don't skydivers usually carry a second reserve, like the belly mounted kind those test jumpers use when doing intentional cutaway demonstrations? If the fail rate of a parachute is 1/1000, then the chance of all 3 failing would be one out of a billion, which I think is minimal. Wouldn't that make us more comfortable? I know I sound a bit paranoid here thinking about double malfunctions but I think having a 3rd parachute would give me more confidence in the case of a necessary cutaway..

Is it that the altitude would not allow the use of a second reserve, or is it the belly mount being really cumbersome, that prevents its widespread use?

And btw I don't think the fear of being called a wussy is a valid reason for not considering this practice:)

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Why? Simply because the skydiving world regards the amount of effort expended would exceed the gain. You can explore the all the reasons with your question, but it will always come back to this simple bottom line.
Always remember the brave children who died defending your right to bear arms. Freedom is not free.

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Thats simple! If you had a second reserve then you couldnt call the first reserve a reserve because you have a second reserve which also means if the first reserve doesnt exist then there is no second reserve. So now, just because you tried to add a second reserve, you now dont have a first or a second reserve and the faa clearly states you have to have a reserve!

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It's not the belly mount in your example, but I heard an interview with Bill Booth(?) about a triple-canopy container. He said that one had been invented and prototyped, but the increase in complexity actually made it less safe than the dual-canopy container. You needed 2 more handles that could not be mistaken for the other handles, and increased complexity in what's going on in the back with the risers, another set of 3-rings, etc. So they decided it was less safe and that 2 canopies in a container is the best number.

"So many fatalities and injuries are caused by decisions jumpers make before even getting into the aircraft. Skydiving can be safe AND fun at the same time...Honest." - Bill Booth

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chrischan1985

If the fail rate of a parachute is 1/1000,



Which it may be, in very rough terms, ....for a main parachute, including typical operational factors that don't involve the design itself.

Reserve parachutes are probably an order of magnitude more reliable. At least that, I hope.

Reserves don't get packed in 5 minutes before the next load, with lines with 800 jumps on them, so there are operational reasons for improved reliability. That's in addition to the much more conservative design than used for the faster main parachutes.

That still doesn't get to the one in a billion you were talking about, but whatever the stats are, it is regarded as safe enough. Especially when there are so many more ways to die, so many more things to watch out for, that failed reserves are a tiny, tiny fraction of all skydiving fatalities.

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Thanks Jeff! I was not even aware this kind of design existed.. I can imagine how challenging it would be to operate them in the right sequence in an emergency. Certainly don't want to cutaway reserve #1 when the main fails:D

The belly design however, has always been around, so that is why I asked about it. I am certain using that requires special training too, but in my opinion it could be worth it. But that's just me.

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pchapman

***If the fail rate of a parachute is 1/1000,



Which it may be, in very rough terms, ....for a main parachute, including typical operational factors that don't involve the design itself.

Reserve parachutes are probably an order of magnitude more reliable. At least that, I hope.

Reserves don't get packed in 5 minutes before the next load, with lines with 800 jumps on them, so there are operational reasons for improved reliability. That's in addition to the much more conservative design than used for the faster main parachutes.

That still doesn't get to the one in a billion you were talking about, but whatever the stats are, it is regarded as safe enough. Especially when there are so many more ways to die, so many more things to watch out for, that failed reserves are a tiny, tiny fraction of all skydiving fatalities.

That makes sense. Thanks!

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Why not another belly reserve?
In a nutshell, because we don't want to. :)
Nobody or nothings prohibits you to modify a regular harness to install the snaps to mount a belly reserve in front of you.
I've seen it done when they test prototypes and plan on intentional cutaways, it's a "standard" procedure (actually, in these cases it's mandatory).
I guess you could do it for your "normal" gear too but they already told you the reason why we prefer not to.
I'm standing on the edge
With a vision in my head
My body screams release me
My dreams they must be fed... You're in flight.

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JeffCa

It's not the belly mount in your example, but I heard an interview with Bill Booth(?) about a triple-canopy container. He said that one had been invented and prototyped, but the increase in complexity actually made it less safe than the dual-canopy container. You needed 2 more handles that could not be mistaken for the other handles, and increased complexity in what's going on in the back with the risers, another set of 3-rings, etc. So they decided it was less safe and that 2 canopies in a container is the best number.



In this case the KISS princible seems about right...

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It is a legitimate question. And has been answered in various ways. The million to one theory does not seem at first to be valid, because of the complexity... or maybe we just want the "decision tree" to be a small one.

Consider the complexity of the tandem decision tree.

Fun to just think of the many scenarios, the possible training.....

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dpreguy


Fun to just think of the many scenarios, the possible training.....



Has anybody ever landed a 3-out?

"So many fatalities and injuries are caused by decisions jumpers make before even getting into the aircraft. Skydiving can be safe AND fun at the same time...Honest." - Bill Booth

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JeffCa

***
Fun to just think of the many scenarios, the possible training.....



Has anybody ever landed a 3-out?

They say the first guy who had one is still floating around up there, somewhere... ;)
You are playing chicken with a planet - you can't dodge and planets don't blink. Act accordingly.

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Surely another reason is that terts for intentional cutaways are usually used when the cutaway is performed with plenty of alti? By the time the main and secondary (reserve) have been cutway, there would be far fewer instances where there'd be enough time for deploying another reserve. It would also seem that the 1/1000 "multiplier" would be much less effective than for the first reserve since many of the scenarios where a normal reserve "fails" wouldn't likely to be fixable with a third parachute.

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a simple answer is that there usually just isn't enough altitude for a 3 rd reserve to be practical, as well as what others have said about the very unlikely event of a reserve malfunction.
Have you seen my pants?
it"s a rough life, Livin' the dream
>:)

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Let's say you were willing to carry the weight and bulk that would be required to have a rig with three reserves. If you were to split that weight and square footage between the main and primary reserve canopies I think you would go much farther towards increasing your safety with out sacrificing the simplicity of the system.

Just saying, look at the stats. I'm hard pressed to think of any one who died because their canopies, particularly the reserve, were too big. But there are a lot of people in the ground that might like to go back and rethink their wing loading given the chance.

Lee
Lee
[email protected]
www.velocitysportswear.com

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I've heard some suggest a tersh system where the "second reserve" has a single-point-of-attachment, has no pilot chute and is hand-deployed (thus no 2nd cutaway decision tree) similar to a paraglider reserve. Just added aerodynamic deceleration. I'd be interested in hearing your (and others', especially other riggers' or highly experienced jumpers with a long time in the sport) well-considered opinion of that. (Obviously requires thinking outside the current "box".)

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Yeah Andy that's more like the traditional tersh in the sense used by CRW guys in the early 80s, although it was still rare then. It wasn't just snapping on an old belly mount with throw out canopy. Back then it would have been a hang gliding reserve (since paragliding didn't exist as a sport), or something custom built based on the same concept. I don't know the exact details as I wasn't jumping then.

While unsteerable rounds like in hang gliding do have a single bridle, for paragliding the single bridle does split into 2 risers at the shoulders. So opening shock and landing isn't taken half on one's side.

For those not familiar with the systems, the system is "hand deployed" but not like an old military belly mount. For a paragliding reserve, the handle on the container is connected to the bag. So you don't need to grab a bundle of canopy and toss it out, you just pop the pins and toss the whole bag in the desired direction. There's no pilot chute and bridle on it, so nothing to wrap around itself or to pull itself straight up into the malfunctioning main. The bag opens from inertia - when it comes to the end of the lines the momentum from the mass of the canopy will pop the last line stow. (There have been a couple with drag pockets on the bag, to give it a little extra drag.)

Some things are different with paragliding reserves but I won't get into the details. As is, they aren't suitable as a skydiving tersh as they are designed to open fast, which is good at very low speeds, and only designed for say 80 mph maximum test speed in certification. With the new low bulk fabrics the recent designs have become more compact. Bridle lengths have to be chosen for the right application -- so a HG reserve might have a long bridle to clear the glider, while a PG reserve might be shorter to stay short of the paraglider on its long lines.

Paragliding reserves have tended to stay as rounds due reasons including to the low altitude two-out issues and not normally having a cutaway system. But Rogallo wings also exist (and one cuts away one side of the main after deployment to streamer the main behind you), or for pilots doing aerobatics, a square with a full cutaway has been used too.

Most people don't need a 3rd canopy, but if one were building something nowadays, some combining of both skydiving and paragliding knowledge would help in building something appropriate for hand deployment past a malfunctioning regular reserve with no cutaway.

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JerryBaumchen

Hi chris,

Quote

I was not even aware this kind of design existed.



Here you go,

JerryBaumchen


Good thing that doesn't look sketchy as hell. ;)
Every fight is a food fight if you're a cannibal

Goodness is something to be chosen. When a man cannot choose, he ceases to be a man. - Anthony Burgess

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Then you might need two altimeters, two AADs, two helmets, two audibles, two mains, etc.
Also today most of the accidents are under beautyfull fully inflated canopys .....
Keep it simple!, the parachute for idiots is not ready yet, I heard this one time from Bill Both mouth.
Keep jumping and you will understand soon why a second reserve is not an option..
;)

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Well, if you want to be a Strong Tandem Master you might have to. That's Strong's intentional cutaway rig. Has handles set up to mimic Dual Hawk Tandem rig. Fun to jump and absolutely no issue with three ring. Every jump is a cutaway!;)

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

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