Dual Brake Line Idea

[pBASEtobe 0]

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I have done it from airplanes. I found the slider noticeably slowed.

Ok then...for jumps you would normally do with a fine mesh slider, why don't you do it with a large mesh slider with the brake lines routed outside the grommets and keeper rings. Used with those risers I had made (blow free risers? [pics]) this might give you the same opening speed with the easy ability to clear line overs. Or is there a huge difference between brake lines in and out the slider grommets, bigger than the difference between large mesh and small mesh? Anyone?

[nicknitro71 0]

Lots of questions very little empirical data

As for fine vs. large mesh I like fine mesh better and I know few other people who don't use large mesh anymore. Apparently fine mesh gives more consistent openings but again data is limited. That's the big problem with BASE, not much data and too many confounding variables.

Memento Audere Semper

903

[base736 0]

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but I've heard from a few knowledgeable people that your brakelines takes most of the stress of deployment.

No, the center A lines take the most impact that's why on some reserves the center A and B lines are non-cascaded.

On the other hand, brake lines are usually made with a heavier-guage line. I expect Poynter has something to say about it (and that the truth of the matter sides with you, since I'm just making this stuff up). Anyway, with respect to bringing the slider down, I wouldn't expect the center A lines to be particularly relevant, since they're in the center.

Parachute Lab does some really cool simulations, including some on ram-air canopies. Here's the tension along the warp direction on the bottom skin, slider-reefed. It's might be hard to make out -- the nose is to the left, and we're looking at a cutaway view of the right side of the canopy. Note that the forces are generally strongest near the tail. The parent page is a lot of fun for those with any inclination toward simulations.

[Cue "think less, jump more" in 3... 2... 1...]

[nicknitro71 0]

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On the other hand, brake lines are usually made with a heavier-guage line. I expect Poynter has something to say about it (and that the truth of the matter sides with you, since I'm just making this stuff up). Anyway, with respect to bringing the slider down, I wouldn't expect the center A lines to be particularly relevant, since they're in the center.

The initial load is taken most by the center A lines. Also the brake lines are usually thicker (not the case in skydivig canopies for the most part) not because they have to take more load but because of the additional wear from the grommets and rings in the case of slider up.

Who said anythign about A lines and slider descent?

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Parachute Lab does some really cool simulations, including some on ram-air canopies. Here's the tension along the warp direction on the bottom skin, slider-reefed. It's might be hard to make out -- the nose is to the left, and we're looking at a cutaway view of the right side of the canopy. Note that the forces are generally strongest near the tail. The parent page is a lot of fun for those with any inclination toward simulations.

Do you know the time of the inflation of the simulation pic?

Memento Audere Semper

903

[base736 0]

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Who said anythign about A lines and slider descent?

I have this habit of assuming that a reply is in the context of the message it replies to. I'm wierd like that.

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Do you know the time of the inflation of the simulation pic?

No idea. But it looks to me like it's either very late (in which case there'd be no point in mentioning that it's slider-reefed), or a static simulation with the slider fixed at some point on the lines...

[nicknitro71 0]

Interesting...Do you know any details on the model?

Canopy opening (RAM air) is one of the toughest problems in fluid dynamics...

Memento Audere Semper

903

[460 0]

I thought Vertigo (Apex now I guess) invented the WLO toggle for slider up line overs. Restricting the tail with a tailgate slider up, so long as it doesn't hangup, should restrict the brake lines to the extent should very rarely result in a lineover.

Looks like a death sandwich without the bread - Steve Deadman Morrell, BASE 174

[base736 0]

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Interesting...Do you know any details on the model?

Not certain. From the other pics, it's 7-cell. If I recall correctly, they make reference to "Parafoil" at one point a lot of people seem to use that as a generic term from ram-air canopies.