Forums: Skydiving: Gear and Rigging:
'Slowest' Slider.

 


ryanl2006  (B 30967)

Aug 2, 2007, 8:29 PM
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'Slowest' Slider. Can't Post

I have been thinking a bit lately on how the slider slows the opening. I know it chokes the lines to the canopy to control how fast it inflates, but my question is 'what is the slowest sized slider?'

Let me explain a bit further. Initially I thought that a smaller slider would cause slower opening due to more 'choking' force, but after searching and reading here I have found that a smaller slider will cause faster opening, I guess because due to smaller size there more force pushing it down.

So at what size does the slowest opening occur? Obviously there must be some point where a bigger slider will actually cause a faster opening, take the extreme example, if the slider was the same size as the canopy there would be no 'choking' at all so the canopy would open as if there was no slider. Does the slowest opening happen when the slider is a set size, say 1/10th as wide as the distance from outermost lines, or does it vary from canopy to canopy?

There is no real reason behind this question, I am just curious about the physics behind opening.


diablopilot  (D License)

Aug 2, 2007, 9:11 PM
Post #2 of 13 (971 views)
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Re: [ryanl2006] 'Slowest' Slider. [In reply to] Can't Post

There is no "right" answer.

Some canopies require a small slider, some a large slider to open softly.

I have seen hard opening canopies fixed by going both ways.


bob.dino  (E 2185)

Aug 2, 2007, 9:27 PM
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Re: [ryanl2006] 'Slowest' Slider. [In reply to] Can't Post

There are a number of forces acting on a slider during the opening sequence.

Just after the canopy comes out of the d-bag, you're still descending vertically. The canopy is trying to inflate -> lines move further apart, pushing down the slider. In opposition to this is the force created by the air on the slider, holding the slider up the lines.

As you decelerate, the force holding the slider up the lines decreases (because the force from the air is less) and the slider moves down, allowing the canopy to continue to inflate.

As to the "one true size", I don't think there's one. But then I'm not a parachute designer.


bodypilot1  (D 16037)

Aug 2, 2007, 10:21 PM
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Re: [diablopilot] 'Slowest' Slider. [In reply to] Can't Post

 
In reply to:
I have seen hard opening canopies fixed by going both ways.

Leave your personal life out of this........ LaughTongue


Be safe
Ed


diablopilot  (D License)

Aug 2, 2007, 10:24 PM
Post #5 of 13 (946 views)
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Re: [bodypilot1] 'Slowest' Slider. [In reply to] Can't Post

Shush sailor, or I'll scratch your eyes out.Tongue


ryanl2006  (B 30967)

Aug 2, 2007, 10:37 PM
Post #6 of 13 (940 views)
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Re: [bob.dino] 'Slowest' Slider. [In reply to] Can't Post

Ahhh well. I figured the answer would be it depends. Thanks guys.


blackj  (D 482)

Aug 3, 2007, 2:13 AM
Post #7 of 13 (906 views)
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Re: [ryanl2006] 'Slowest' Slider. [In reply to] Can't Post

As a side note a bigger slider doesn't mean a slow opening. If the slider is to big then more of the canopy when it get out of the bag can inflate before it has to work against the slider. You get a very hard snatch force but the rest of the opening will be quite slow.


Ronaldo  (D 34728)

Aug 3, 2007, 7:30 PM
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Re: [ryanl2006] 'Slowest' Slider. [In reply to] Can't Post

The ideal solution would be to create a small slider (lots of reefing effect) but with the drag of a bigger one (longer snivels). Thats why pockets and domes work so well, they combine the best of both (reefing of small and drag of larger).


riggerrob  (D 14840)

Aug 4, 2007, 8:30 AM
Post #9 of 13 (744 views)
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Re: [Ronaldo] 'Slowest' Slider. [In reply to] Can't Post

The slowest slider would have the same distance between grommets, but would be have small grommets (say # 5) be domed and have pockets, lips and flags hanging off all sides.


diablopilot  (D License)

Aug 4, 2007, 8:43 AM
Post #10 of 13 (742 views)
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Re: [riggerrob] 'Slowest' Slider. [In reply to] Can't Post

AND pilot chute reefing.Laugh


riggerrob  (D 14840)

Aug 5, 2007, 7:16 AM
Post #11 of 13 (686 views)
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Re: [diablopilot] 'Slowest' Slider. [In reply to] Can't Post

In reply to:
AND pilot chute reefing.Laugh

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

No need to be shy.
Let's install a double-length bridle and a pair of spring-loaded pilot chutes!
Tee!
Hee!


RMURRAY

Aug 5, 2007, 8:07 AM
Post #12 of 13 (678 views)
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Re: [ryanl2006] 'Slowest' Slider. [In reply to] Can't Post

I know first hand tha a dome slider (of equal size to factory slider) works great on a problem canopies. For example a sabre 1. MEL (skyworks rigging) explained it to me once - a dome slider is "self correcting" so it will never stand on an edge and come rocketing down the lines like a regular or pocket slider can.

rm


packing_jarrett  (D License)

Aug 5, 2007, 8:51 PM
Post #13 of 13 (626 views)
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Re: [ryanl2006] 'Slowest' Slider. [In reply to] Can't Post

In reply to:
if the slider was the same size as the canopy there would be no 'choking' at all so the canopy would open as if there was no slider.

In my limited experience I would say that wouldn't happen. The canopy will stay in the burble of the slider and thus choking it off. I experienced this while jumping a R.A.G.E. (107?) by Paratec. I did some jumps on that and every time I pulled, the slider was so huge that it didn't even let the canopy inflate. Of course when I started yanking on the yonkles the slider started coming down.

My 2 cents



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