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fcajump

Dealing with high shock loading

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Yes it was a thing. There were a few canopies that tried to use it. It doesn't work very well. The PC is in the burble of the canopy and provides inconsistent drag and the line burns up the canopy as it passes through. Solid sliders that block the wind into the canopy work much better. Good thought, but it turns out that it doesn't work well.

Lee
Lee
lee@velocitysportswear.com
www.velocitysportswear.com

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I seem to recall some folks rubber banding sliders in the old days. Might have been the free packers. Obviously that’s not an exact science as it was done in 1980 or so, but a hesitator of some kind might stage the opening better.

I didn’t because I built a diaper that contained everything until line stretch. At least all but one the times I used it :P, and that time I know I didn’t roll the nose enough.

Wendy P.
There is nothing more dangerous than breaking a basic safety rule and getting away with it. It removes fear of the consequences and builds false confidence. (tbrown)

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>That's the simple solution. Why not just put a tailgate on the slider?

Because that won't solve the problem.

People seem to think rogue openings happen because someone screwed up, or the slider was in the wrong place, or that something else went wrong (often with the caveat "which isn't a mistake I would make.")

Rouge happenings can open even when parachutes are properly packed and maintained. There's no one solution that will solve the problem, although a great many solutions can reduce the odds of it

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gowlerk

Rouge openings like this can only happen it the slider fails to do it's job. It would probably be better and simpler to focus on finding ways of ensuring that sliders stay all the way up until line stretch.



Yes! Simple solution; magnets on the slider stops. Tabs could work as well, similar to slider locks on the risers but sewn on the slider stops instead. This would certainly help to keep the slider in place during the packing process.
Onward and Upward!

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billvon

>That's the simple solution. Why not just put a tailgate on the slider?

Because that won't solve the problem.

People seem to think rogue openings happen because someone screwed up, or the slider was in the wrong place, or that something else went wrong (often with the caveat "which isn't a mistake I would make.")

Rouge happenings can open even when parachutes are properly packed and maintained. There's no one solution that will solve the problem, although a great many solutions can reduce the odds of it



If we are looking to solve the problem of the slider coming down early a tailgate (or snaps) would hold the slider in place better.

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billvon

Rouge happenings can open even when parachutes are properly packed and maintained.



Maybe so, but where's the data?
Unless one has high speed video of the opening, one often has no clue what happened. If you have a slammer, do you blame the canopy or blame your packing? Even if you're not sure you did anything wrong?

Not saying you are wrong. Maybe sometimes the spreading forces just happen to be higher than usual, given the way the bottom skin & nose inflates, and pushes the slider down suddenly despite the upward forces on the slider. Maybe it would make no difference if the slider slipped down 1" vs. being physically restrained all the way up by some mechanical connection with light force. Or would it?

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veazer

Would utilizing a pilot chute controlled reefing system (pilot chute attaches through the canopy to the slider to help slow/control its descent down the lines) potentially help with this? No idea what potential issues those have but I'm sure someone's tried it before, right?



We had this for years on JFX's modified for CF (more open nose, dacron lines). Worked great because the faster the airspeed, the more your slider was slowed down. We eventually were able to not have sliders in the conventional sense, but just grommets and rings to the bridle. Packing was way more challenging and we did see some damage to the bottom skin of the canopy, however.

My profile pic is with those canopies, with that system.

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pchapman

***Rouge happenings can open even when parachutes are properly packed and maintained.



Maybe so, but where's the data?
Unless one has high speed video of the opening, one often has no clue what happened. If you have a slammer, do you blame the canopy or blame your packing? Even if you're not sure you did anything wrong?

Not saying you are wrong. Maybe sometimes the spreading forces just happen to be higher than usual, given the way the bottom skin & nose inflates, and pushes the slider down suddenly despite the upward forces on the slider. Maybe it would make no difference if the slider slipped down 1" vs. being physically restrained all the way up by some mechanical connection with light force. Or would it?

I've noticed that wind and turbulence may have an effect on the opening. I've never had a true slammer, but I've had a few harder openings that left me dropping the F word a few times. The canopy sniveled for maybe 1-2 seconds and then the slider magically popped all the way down the lines. Anyway, one thing I noticed is that the few I had occurred in windy or turbulent conditions. As in, as soon as the canopy opened fully it was immediately turbulent and windy.

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If you use a ring on a lanyard to attach the shackle like Ray Farrell's after market RSL that threads through the lower bend of the riser next to the ring. Anywhere the riser breaks the RSL doesn't leave.

Butler isn't the only one to attenuate bridle with sacrificial bar tacks. Preserve V also has a sacrificial lazy leg.
I'm old for my age.
Terry Urban
D-8631
FAA DPRE

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Yes, magnets could be an answer. Especially if they were in pairs with magnets both on the slider and on the stops. That way you could use the polarity of the magnets to be sure the slider was held in the correct Orientation.

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gowlerk

Yes, magnets could be an answer. Especially if they were in pairs with magnets both on the slider and on the stops. That way you could use the polarity of the magnets to be sure the slider was held in the correct orientation.



At least one manufacturer is using magnets for a tailgate, so it's possible to have magnets on the canopy. I'm curious how using magnets for slider control would work, though. How would you ensure only particular pairs of magnets stuck together, especially since in the course of packing they could reorient, rotate, or flip? For example, how would you keep slider magnets from sticking to other slider magnets?

--Mark

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mark

*** Yes, magnets could be an answer. Especially if they were in pairs with magnets both on the slider and on the stops. That way you could use the polarity of the magnets to be sure the slider was held in the correct orientation.



At least one manufacturer is using magnets for a tailgate, so it's possible to have magnets on the canopy. I'm curious how using magnets for slider control would work, though. How would you ensure only particular pairs of magnets stuck together, especially since in the course of packing they could reorient, rotate, or flip? For example, how would you keep slider magnets from sticking to other slider magnets?

--Mark

Those are good questions. And I had not thought of that problem.
Always remember the brave children who died defending your right to bear arms. Freedom is not free.

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Westerly



lmost everyone I know who has at least 1000 jumps has mentioned having at least one hard opening that was hard enough to cause injury (ranging from moderate to serious). So I think hard openings are far more common than they should be.



I don't think that they are that common. I have between 10-11,000 jumps and have had only two really hard opening. Some brisk ones over the years but only two which actually left me sore the next day.

One was when I dumped a belly mount round reserve at terminal (definite ouch). The second was when I took a tail-pocketed mesh slider Lightning CRW canopy to terminal (The trail plane was REALLY high and if I didn't do a long delay I wouldn't get in. I was the only person from the trail plane to dock :) I was definitely sore the next day though - but I knew that I would be when I did it!)

I suspect that they are more common in places where fewer people pack for themselves and they have their rigs packed by rushed packers instead of taking time to do it themselves.

Definitely any canopy can have a rogue opening, but I definitely think some are much more prone to it than others.

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gowlerk

****** Yes, magnets could be an answer. Especially if they were in pairs with magnets both on the slider and on the stops. That way you could use the polarity of the magnets to be sure the slider was held in the correct orientation.



At least one manufacturer is using magnets for a tailgate, so it's possible to have magnets on the canopy. I'm curious how using magnets for slider control would work, though. How would you ensure only particular pairs of magnets stuck together, especially since in the course of packing they could reorient, rotate, or flip? For example, how would you keep slider magnets from sticking to other slider magnets?

--Mark

Those are good questions. And I had not thought of that problem.


Use snaps. Some HP canopies already do this.

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LeeroyJenkins

That's the simple solution. Why not just put a tailgate on the slider? It can be done while propacking and only takes a few extra seconds.




Ok... you lost me on that one... anyone got a good description (pics would be best), not sure I've run across a tailgate before (insert pickup truck joke here). Or maybe its just too early in my day...

JW
Always remember that some clouds are harder than others...

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Quote

anyone got a good description (pics would be best), not sure I've run across a tailgate before (insert pickup truck joke here).



A search will turn up various BASE web pages. Basically a tailgate holds the brake lines together temporarily, for a better controlled opening with less lineover potential, holding them up near the canopy, by using an elastic band and a dacron tab mounted to a line. Normally used without a slider but can be used with one, and can be mounted on the slider too (hence the connection to to the 'holding the slider in place' stuff in this thread). One video that shows some of the variations fairly clearly:
https://www.youtube.com/watch?v=Cz_2hjEyUGM

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A low placed RSL ring through the bottom loop only helps if the bottom of the riser stays with the rig. People keep talking about risers breaking at the grommet hole but oddly the majority that I have seem break snapped at the tape of the third ring. I mean that tape broke. This means that the whole riser released. This is 3 out of the 5 I've seen break. One did break at the grommet and one broke at the front riser.

Snaps, magnets, or just rubber banding the center of the slider up to one of the attachment points certainly helps to avoid the occasional brisk opening. I don't think this is a bad thing at all. I don't think it's a solution to the explosively hard openings that break things and kill people. We're not talking about some thing that leaves you sore. These are like an order of magnitude higher. I don't think they are a product of the riser creeping down. I think they are the result of a much grosser failure of the staging of the canopy. Like Dennis. I figure he got one riser caught under the corner of his tray on that sit fly deployment. This difference in length means that one side of the risers and there fore the slider was pulled down about 4 feet lower then the other. One side could almost fully open unhindered and then the riser pops lose and the canopy is fully open. It was a specter if your curious, not that it matters with some thing like this. I suspect sever out of sequence openings, bag dumps played a part in some others as well.

That's why I'm comfortable talking about a weaker riser or other fail point. The magnitude of the peak forces are way beyond the change due to wear.

Lee
Lee
lee@velocitysportswear.com
www.velocitysportswear.com

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Deja Vu all over again. When I started the slider wasn't quite universal yet but it shortly took over since it worked so well. It not only worked well but was easier to use. It was beautiful. And for 40 years or so now it's been doing its job. At least until recently. Some of the equipment seems to have finally evolved past the slider.
What I'm hoping is that Bill Booth or some of the other gear Einsteins are working on a replacement. Not a modified slider but a whole new piece of technology.
And no, I don't have a clue what it would look like or how it would function. But that won't matter. I'll buy one when they release them.

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veazer

Would utilizing a pilot chute controlled reefing system (pilot chute attaches through the canopy to the slider to help slow/control its descent down the lines) potentially help with this? No idea what potential issues those have but I'm sure someone's tried it before, right?



The first Ramair jump I did was on an early Strato Star, which had the pilot chute reefing system in place, but that system didn't have a slider. Instead you had a bridle cord that consisted of 20 odd feet of rope that went down through the canopy and through rings around the bottom of the canopy.

It worked fine, but was made redundant when the slider came out.

I remember hearing about the Volplane, which apparently had some sort of hydraulic system which you could apparently set for terminal/sub terminal jumps, but I know nothing about how it worked.

I saw one jumped once, as I recall. It was owned by an old guy who was a physics professor, so maybe the hydraulic system was his own invention. I can't imagine how it would work. People were messing around with the early squares at that stage.

Apparently the Volplane had the performance of a cheapo.

Maybe an older fart than me can elaborate on that.

ETA: Just found something about them on this very site...so the reefing system came out with the canopy.

Maybe we could begin by looking back to help sort out the future. The Delta 2 OSI system is another. Modern versions could be a starting point.

http://www.dropzone.com/forum/Skydiving_C1/Skydiving_History_%26_Trivia_F21/Volplane_Hydraulic_Reefing_Device_P4582058/
My computer beat me at chess, It was no match for me at kickboxing....

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Finally someone thinking about coming up with a replacement for the line eating slider. The "Einsteins" would have to get very lucky to do better than the slider, but I know there must be a next system possible. Whether the Einsteins come up with it or just a beginner with a suggestion that the Einsteins can take credit for, it would be a great step forward. Thank you Bob for starting this in this direction. As far as holding the slider up, if it is the problem with these hard openings, Ray Farrell again, has an approved system called the "secure slider system". If he asks Ray nicely, he may send him a copy. D-3411

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HPC

This has been done before on earlier canopies, possibly accuracy canopies but I'm not certain, my memory isn't quite what it was.



My first square had it. It was the opposite of a slider. Complicated, a pain to set up and seldom worked. Oh, and it tended to damage the canopy. Sometimes it would open so hard it pressed my risers into the side of my face. The only thing that saved me was that this canopy was such a worthless piece of shit that it usually took over a thousand feet of blue green blue green to finally open. That, basically, was its reefer system.
The thing that made it a little hard to believe you should switch to the slider was looking at all these complex things that weren't working very well then being told that this little simple to use thing would. But it did.

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