Hypothetical Slider Discussion

[darkwing 5]

You make the mistake of thinking that just because nothing obvious has developed recently, that there hasn't been development. As others said, there were many variations tried back in the 1970's mostly, and lots of variations on sliders themselves. I know because I tried some of them. I think what we have is known as "mature technology." which is not to say that we shouldn't keep trying, but sliders are very simple devices, and they are an elegant solution to a complex problem.

Note also that if you do too much designing of a canopy to optimize openings, it can interfere with how the canopy performs after it is opened. There are always design tradeoffs.

-- Jeff
My Skydiving History

[mjosparky 4]

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You could jump a (square) canopy all day without a slider as long as you never took it to terminal velocity.
BASE jumpers do that every day.

You might want to rethink this statement. Base jumpers launch at 0 mph. A skydiver leaves the aircraft at 80/90 mph.

I have seen two people jump from a Howard with the slider packed in the down position. One suffered a compression fracture of his cervical spine and the other almost bit off his tongue

Sparky

My idea of a fair fight is clubbing baby seals

[RiggerLee 61]

I've got about twenty slider down jumps from 182's. In all honesty it is a bit rough but survivable. Remember the size trim and break setting are big factures. Small canopies are a smaller wall to hit the air. And let's be honest. I'm just not that bright.

Lee

Lee
lee@velocitysportswear.com
www.velocitysportswear.com

[mjosparky 4]

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And let's be honest. I'm just not that bright.

After the first 4 or 5 most people would have seen a trend.

Sparky

My idea of a fair fight is clubbing baby seals

[Martini 0]

When I first read this post I thought it was kinda dumb, why try to change something that is so simple and works so well? Then, after a few days thought and several bottles of wine it occurred to me that the slider could use improvement in one area. You can change the opening characteristics of a canopy by using various packing techniques but the single most important control mechanism is the slider. The slider, while factory "optimized", isn't adjustable in any way. It sets up against the stops, it gets reset and that's it. Yeah there are subtle things you can do like cloverleaf or not, and a much larger impact on openings can be had by varying the amount of exposure of slider past the canopy nose. But the slider itself is in no way adjustable. Having the ability to tailor the slider to desired opening style or for hop and pops vs. freeflying or line shrinksge or whatever might be useful to some people. Maybe not for everyone but for some it might be a real advantage. Instead of reinventing the wheel how about just improving the one we have now? As usual, the more complex things are the riskier they become. Some are willing to make the trade, some are not.

Sometimes you eat the bear..............

[ryoder 1,590]

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Capewells worked fine as releases before three rings;

Sure if you didn't mind them occasionally jamming up. They were never intended to be used in mid-air, but only to attach/detach the harness from a packed canopy which stayed with the plane.

"There are only three things of value: younger women, faster airplanes, and bigger crocodiles" - Arthur Jones.

[ryoder 1,590]

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With rings and ropes there were two types. Top surface and bottom surface. I haven't had a chance to jump my Strato-Star but have been told that the underside rings and ropes work better than the top surface.

Whether you preferred top vs bottom ropes & rings was just a matter of whether you preferred holes burned in the topskin, or if you preferred your suspension lines burned in half.

"There are only three things of value: younger women, faster airplanes, and bigger crocodiles" - Arthur Jones.

[ryoder 1,590]

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A simplified version of ropes and rings was the pilot chute controlled slider, basically a rope tied to the bottom of the pilot chute and the top of the X slider. The rope was routed straight down through the center of the canopy. Some military HAHO and HALO jumper still use double-length PCCS, because they work better at the high speed edge of the envelope.

I had a PCCS on a Parafoil. When I first got it , it was slamming the hell out of me. I called the mfgr to complain. He asked what size PC I was using. I told him I was using the stock PC that came with a Wonderhog.

Mfgr: "Oh, you need a 40" PC."

Me: "Well why the hell didn't you bother to mention that in the docs you provided with a brand new canopy???"

At the time no one was using PC's that large, so I had a local rigger build a custom one. From that point on, that canopy gave me the smoothest openings I've ever had!!!
The downside was the bridle passing through the center of the canopy caused burns on the two adjacent ribs, and within a 2' radius on the top & bottom skins.

"There are only three things of value: younger women, faster airplanes, and bigger crocodiles" - Arthur Jones.

[Beatnik 2]

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Sure if you didn't mind them occasionally jamming up. They were never intended to be used in mid-air, but only to attach/detach the harness from a packed canopy which stayed with the plane.

I'll agree with them originally not intended to be used in air. Maybe I am wrong on this, but I believe there original intent was to allow paratroopers to release their canopies if they were being dragged in high winds, some were even dragged to their deaths. Without going through some of my books, I believe it was a couple years after the end of WWII the Capewell release was invented with this reason in mind.

[ryoder 1,590]

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Sure if you didn't mind them occasionally jamming up. They were never intended to be used in mid-air, but only to attach/detach the harness from a packed canopy which stayed with the plane.

I'll agree with them originally not intended to be used in air. Maybe I am wrong on this, but I believe there original intent was to allow paratroopers to release their canopies if they were being dragged in high winds, some were even dragged to their deaths. Without going through some of my books, I believe it was a couple years after the end of WWII the Capewell release was invented with this reason in mind.

Now that I think about it, I believe you are right due to them being on troop harnesses. There were also a couple other designs, (eg the Koch and the Rocket Jet), that were designed with pilots in mind.

I had a homebuilt cutaway rig with Rocket Jet fittings on it. Through Yankee ingenuity I managed to get a bag lock on it one day, and I am still amazed how fast I was able to grab two flailing Rocket Jets, depress the buttons in both sides, and release them, (with gloves on).

Edited to add: Swell, now it looks like attachments are broken.

"There are only three things of value: younger women, faster airplanes, and bigger crocodiles" - Arthur Jones.

[RiggerLee 61]

As to modifing the slider to adjust openings...That's interesting. First I should point out that one of the easiest ways to change the opening is to change the break setting but here are some other thoughts. If you had a pleated "dome" slider you could put a strap across the center of it in a channel like a kill line but fastened on each end with a fast tec so you could compress it to take the "dome" out of the slider. Another thought is a slightly adjustable slider stop. I'm envisioning something that would slide along a peace of tape and lock in place. Lowering the slider stops is one of the best ways to speed up the opening of a canopy. I can think of at least one canopy that added weights to the slider to try to speed the openings of their canopies.
Now it's late at night and I'm just rambaling but hay, we're brain storming right?

Lee

Lee
lee@velocitysportswear.com
www.velocitysportswear.com

[Martini 0]

Having several brake settings (like on some BASE rigs) is an interesting idea, naturally it requires attention to prevent interesting malfunctions. Adjustable slider stops seem reasonable too. I've experienced the use of different slider weights but only to bring the slider fully down not to change openings. How about this: a slider with a large hole in it, the hole can be closed or opened by use of a locking drawstring to regulate the opening size. Yes it is late and I'd be brainstorming if I had one.

Sometimes you eat the bear..............

[mnealtx 0]

Wouldn't that have the effect of a *much* smaller solid slider when the hole is completely closed off? In essence, no real difference from the larger, "open hole" slider?

Edit to add: On second thought, it *might* be slower due to the lines being held closer together by the "closed" slider.

Mike
I love you, Shannon and Jim.
POPS 9708 , SCR 14706

[riggerrob 643]

Try thinking of a corral (4-sided wall) of fabric with grommets in the bottom corners and a draw-string around the top edge.
As you tighten the draw-string, the hole in the center becomes smaller. When the draw string is completely tightened, it acts like a regular fabric slider, with only a tiny hole in the center.
The distance - between grommets - does not change because you started with plenty of slack.

[riggerrob 643]

I can think of at least one canopy that added weights to the slider to try to speed the openings of their canopies.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Funny,
About five years ago, I traded e-mails with a guy from Arizona who was experimenting with light-weight slider grommets in an effort to reduce "slider rebound."
His theory was that any gap between the slider and the bottom skin vastly increased the risk of hard openings.
He suspected that suspension line elasticity sometimes catapulted the slider off its stops, then any momentum kept it sliding down the lines.
The other issue was that sometimes the weight of the slider caused it to sag away from the bottom skin as it was lifted off the jumper's back.

His theory was that lighter slider grommets would result in more consistent, softer openings.
He experimented with grommets made of aluminum tubing,but never went to market.

[mnealtx 0]

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Try thinking of a corral (4-sided wall) of fabric with grommets in the bottom corners and a draw-string around the top edge.
As you tighten the draw-string, the hole in the center becomes smaller. When the draw string is completely tightened, it acts like a regular fabric slider, with only a tiny hole in the center.
The distance - between grommets - does not change because you started with plenty of slack.

Howdy, Rob - hope you've been ok.

I follow you on the description - the 'closed' configuration would be similar to a shallow dome slider at that point, wouldn't it? (except for the small hole at the apex, of course).

Mike
I love you, Shannon and Jim.
POPS 9708 , SCR 14706

[Martini 0]

If I ever thought "slider rebound" was an issue or had concerns about the slider drifting down the lines I would hitch a rubber band around a center "C" line attatchment point and band the top of the slider up like some BASE guys do for slider-up jumps. How about magnets at the slider stops and nickel or 400 series stainless grommets or brass grommets with bits of iron sewn in.

I do have a good test canopy for the hole and drawstring slider idea, a Xaos that wii snivel an honest 1500' if you let it. The slider also likes to hang up so more weight would help. I even have an extra slider for it but it's being used on another canopy. And I have a plan for the system and expert sewing ability (my wife). I'll build the slider but I need George Galloway or some benefactor to pay for the test jumps.

Sometimes you eat the bear..............

[relyon 0]

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Capewells worked fine as releases before three rings;

Sure if you didn't mind them occasionally jamming up. They were never intended to be used in mid-air, but only to attach/detach the harness from a packed canopy which stayed with the plane.

OT - I didn't mention anything about where a given release is used.

Bob

[ryoder 1,590]

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Try thinking of a corral (4-sided wall) of fabric with grommets in the bottom corners and a draw-string around the top edge.
As you tighten the draw-string, the hole in the center becomes smaller. When the draw string is completely tightened, it acts like a regular fabric slider, with only a tiny hole in the center.
The distance - between grommets - does not change because you started with plenty of slack.

Interesting idea. Has anyone actually implemented it?

"There are only three things of value: younger women, faster airplanes, and bigger crocodiles" - Arthur Jones.

[popsjumper 2]

Your Shiner pic...

Looks like a kneecap strike to me.


Can I be frivolous here?
How about packing a small-person in the canopy? He could hold onto the stabilizers and release them at the right time for soft openings. Just don't piss him off by calling him a midget.
Nah...then you'd have the added expense of having to feed him.

My reality and yours are quite different.
I think we're all Bozos on this bus.
Falcon5232, SCS8170, SCSA353, POPS9398, DS239

[hackish 8]

The slider has stayed because it employs the kiss principle. Very simple and it does work.

Rob and I spent some time discussing a detachable slider but ultimately it is very difficult because there are many considerations.

First you have to make sure it is going to be reliable - unlikely to snag a line or cause a malfunction.

Second you have to make sure it's durable. All the hardware we thought about would have a tough time lasting and withstanding the 1000lb or so MBS required by the slider.

Finally it would have to be easy to pack. Take something complicated and the potential for mistakes goes way up.

There is no simple alternative that works better - that explains why it's been unchanged for as many years as it has.

-Michael

[Beatnik 2]

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Your Shiner pic...

Looks like a kneecap strike to me.

I think it was from a Capewell cover. I was thrown around pretty hard when that thing opened up. Who knows, what it is from. The opening was an instant stop and nothing would surprise me. Some thought it might have been from the reserve. Don't know what it was from and from how hard that opening was, nothing would surprise me.

I have been knocked out a couple of times on openings and this one was close. If I took this canopy to terminal, it probably would have knocked me out. I hate it when that happens but it does make for good stories later.