Queston about slider-down BASE

[JohnGraham 0]

Hi y'all.
I read somewhere (a source I consider reputable, but can't remember exactly where) that when a BASE rig is packed slider down, the brake lines must not be routed through the slider grommets.
How accurate is this? And, what I was really wondering, why is this so important???

[Treejumps 0]

Thats a good start, but optional. Most people do route their brake line outside of the slider grommet and keeper ring. Search "Line Mod" and you will find more detail.

[helge 0]

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.... And, what I was really wondering, why is this so important???

If you get a lineover, it is more likely that it is one of the brakelinkes that is causing it. When the brakelines are routed outside the sliter grommets you can simply toss the corresponding toggle, and the lineover will clear.

[NickDG 23]

Hi John,

The "line-mod" was popularized by a BASE jumper named Mark H. in the late 1980s after he had a lineover malfunction on a LA building that left him impaled on an iron fence.

At the time slider down deployments are allowing BASE jumpers to go lower and lower with great success. Luckily most square canopies of the day (this is years before dedicated BASE canopies) are strong enough to handle these deployments and all's well until one by one lineover malfunctions began to take their toll. No one at the time understood that jumping slider up made lineovers almost impossible and jumping slider down made them almost inevitable. Lineovers and slider down jumps are linked like soup and sandwich. Most, if not all of the lineovers you see at the DZ are packing induced. And to this day skydivers still erroneously call any line, fabric, or slider entanglement a lineover.

Mark noted BASE jumpers are reporting the lineovers they were experiencing on slider down jumps always involved a control line. (The steering lines are much longer than any other lines on a ram air canopy and together with their outboard position it's very easy for them to get over the top.) At first BASE jumpers began carrying hook knifes to cut the offending control line but that proved difficult and dangerous. Finding and cutting the correct line while in a sometimes radical spin proved too much and raised the specter of slicing right through a riser in haste. And unless you cut both steering lines you were left with a hard to fly canopy and a tough landing ahead.

The line-mod simply means the steering lines run cleanly from the trailing edge of the canopy to the risers. The lines do not pass through the slider grommets or the keeper rings on the riser. The brake is locked in the braked deployment position in the normal way.

Jumpers who experienced lineovers could now release both brake lines simultaneously and let them go. This would clear the lineover and allow for a survivable landing while steering and flaring with the rear risers. Mark H. is credited with saving many BASE jumpers during this period.

There were problems of course. Securing the brake lines to the riser in this fashion caused more than few premature brake lines releases. All kinds of fixes were tried, but the one that worked best was going back to something that had fallen out of favor with skydivers at the DZ, and they were called Zoo toggles.

These toggles used steel pins, like straight ripcord pins, to secure the brake line and some form of this is still used today.

Another lesser problem is once the brake lines are released from the riser and the canopy is being flown, if the jumper accidentally dropped or let go of the toggle it's gone for good. Also early jumpers complained flying the canopy was harder due to the fact the control lines aren't thru the riser keepers. (With them thru these riser rings any motion the jumper makes with the toggle translates into a straight down pull on the trailing edge of the canopy.) Jumpers in the habit of making jerky wild ass toggle inputs suffered the most.

However, soon enough jumpers learned this is sort of a blessing. It actually gave them a wider range of control and some talked of using "english" while flying their canopies.

That's about it, John, with the following warnings. Never use the line-mod when jumping slider up as it puts too much strain on the lines and trailing edge of the canopy. If you ever employ the line-mod remember a little bit of riser equals a lot of toggle so be careful of stalling. Also I haven't looked at your profile, so I don’t know what stage you are in, but the above isn't good enough to just go try it. Have a BASE Mentor show it to you or take a BASE course . . .

NickD BASE 194

[JaapSuter 0]

[base283 0]

A functionality test will explain this to you. Tie down your slider and then pull the toggle thru the slider grommet while acting like a line over release mod in action. A good BASE toggle has an extra long stowage area IMHO. This makes a lopsided T with the base of the T being the steering line. What I tried was to take a basic long nose toggle and finger trap the the line tightly around the lowerside of the toggle instead of the grommet. Folding the toggle webbing like a riser end for a streamlined effect. The problems which I encountered with this is the distance below the slider grommet and the angle that the toggle is released. The toggle slingshots and tends to wrap over the slider hindering clearance unless one actually feeds the toggle to the slider grommet and then lets go. Which is difficult if the rear slider groms are not tied down to the riser tops which I do not recommend (because this is old school way).
Have fun,
be careful,
hope this helps,
take care,
space

[460 0]

For slider up, routing the lines outside the slider will drastically slow the descent of the slider, since the slider is primarily driven down by the brake lines.

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

[ZegeunerLeben 0]

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I've succesfully used the LRM on slider-up skydives just for the heck of it, and aside from being prepared for a slider coming down slowly, I don't see too much problems with it...

>>My understanding is that if you use the LRM on slider-up jumps and have a blown toggle, it can entangle with the slider preventing it from coming down, which it would already be having trouble doing. Not a problem on a skydive, you just cut it away. Probably fatal on a BASE-jump, unless you route the brake lines through the keeper rings but outside the slider grommets, and that would defeat the purpose.

[JaapSuter 0]

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My understanding is that if you use the LRM on slider-up jumps and have a blown toggle, it can entangle with the slider preventing it from coming down, which it would already be having trouble doing.

This risk is huge when you put them through the grommets, but not the keeper rings. If you actually take them out of the keeper rings as well as the grommets, the risk is a lot less. It's not neglectible, but unlikely. Especially with properly set and double-checked brakes, I believe this is an acceptable risk in skydiving.

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unless you route the brake lines through the keeper rings but outside the slider grommets; never heard of anyone doing that before.

There would be no point in doing this. The point of doing it vice-versa (grommets but not keeper rings) is that you can push a toggle through the grommet to release it. However, with big-grab toggles, pushing it through a grommet will take too much time. WLO toggles or a hook-knife will save you a lot faster I imagine. I'm not actually talking from experience, so take this all with grains of salt.

[NickDG 23]

>> I don't quite understand how the LRM could put too much stress on the canopy or lines, especially if you use a shallower brake setting.<<

I didn't mean while BASE jumping, I meant while jumping from an airplane. Many new BASE jumpers tried this to get the feel of the line-mod and suffered canopy damage. I've seen it . . .

NickD BASE 194

[JaapSuter 0]

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I meant while jumping from an airplane. Many new BASE jumpers tried this to get the feel of the line-mod and suffered canopy damage. I've seen it ...

Very interesting, thanks! This was something I had not heard of before. It wasn't mentioned in this thread afaik.

[BASE813 0]

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Hi y'all.
I read somewhere (a source I consider reputable, but can't remember exactly where) that when a BASE rig is packed slider down, the brake lines must not be routed through the slider grommets.
How accurate is this? And, what I was really wondering, why is this so important???

A slider down or off deployment is more prone to a line over malfunction. So the control lines are routed outside the slider and keeper rings to allow the LRM (letting go of the offending control line to clear the line over).

People think the tailgate is there to stop "lineovers" for slider down / off deployments, when in fact it is to stop tail inversions, which in itself is also a cause of lineover malfunctions.

If any of my thread is incorrect, please correct me............ as this is how I see it......

[ZegeunerLeben 0]

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This risk is huge when you put them through the grommets, but not the keeper rings. If you actually take them out of the keeper rings as well as the grommets, the risk is a lot less.

>>That makes sense. If the toggle blows and is routed through the slider grommet, it has a much higher chance of hanging up the slider than if routed outside it.

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There would be no point in doing this.

>>Yep you're fast on the trigger Jaap! You got me before I finished editing!

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The point of doing it vice-versa (grommets but not keeper rings) is that you can push a toggle through the grommet to release it.

>>I'd still be worried about the toggle catching on the slider grommet before the slider descended, but like you said that's an acceptable risk on a skydive.

[JaapSuter 0]

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People think the tailgate is there to stop "lineovers" for slider down / off deployments, when in fact it is to stop tail inversions, which in itself is also a cause of lineover malfunctions.

I wonder if anybody has some good footage of tail inversions. I've read about them and I think I sort of understand what they are, but there's nothing like video for some good visualization.

Thanks,

Jaap

[base283 0]

Hellllooo!
The toggle will get slingshotted over slider unless you feed it thru, then, you can see if the toggles can clear the grommets. Hello? is any body listening?.
have fun,
last post on this one topic.
take care,
space

[NickDG 23]

Call it "tail inversions" or "tail flutter" APEX has video of it. They were the first to take notice and give it a name. Skydivers get it too. It's why they find those mysterious faint white marks on the top outboard surfaces of their canopies. It's caused by the upper control lines whipping on the fabric during the tail "flutter."

And, as said, preventing tail flutter brought Apex to implement the Tailgate . . .

NickD BASE 194

[BASE813 0]

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brought Apex to implement the Tailgate . . .

from a real accountancy anal view, you mean BR, as they are a seperate entity!

hehehehe

[NickDG 23]

Come on, Brother, don't you think I know where I worked for years and years? It was Basic Research when they came up with the tailgate but now that BR and Vertigo have merged into one company its all Apex BASE now. (Except for Anne, it's all the same folks.)

And since it was a proper business deal the new company owns all the successes of the prior two. Or, LOL, as one BASE jumper put it, "the stinking globalization of BASE gear manufacturers."

NickD BASE 194

[JohnGraham 0]

WOW!!!
SOOOOOO much information from a single simple question - even in the short time I've been around DZ's, I've very much learnt that there is no such thing as a "quick question" though I consider that a good thing, as you learn more than you even thought there was to learn!

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Also I haven't looked at your profile, so I don’t know what stage you are in, but the above isn't good enough to just go try it. Have a BASE Mentor show it to you or take a BASE course . . .

I have less than 100 skydives (91 or 92, I think... coming up to 100 soon, at least) so I haven't ever made a BASE jump or taken a course, but I definitely want to in the future. For now, I'm just very interested in the rigging/packing/technical side of things and this particular thing bothered me. Thanks to you all for your replies!

[Stewie 0]

I agree with John, this thread provided quite a bit of knowledge. Thanks, guys!

"Fuck that. I'll take a good ass-pounding over a bj any day." -- pyrotech