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I just started packing this way.(inverted tailpocket at the top of the container) The nose is more exposed for inflation then the other.

Any pics or illustrations?
Don't really understand how it works.

I don't think it matters much. Changing the initial placement and folding method helps to get the canopy into the pack tray neatly (and fit to the shape of your container). I don't think it does much, if anything, to inflation.

Once the canopy exits the pack tray, it's pulled straight anyway, so the folds it sat in the pack tray in are already gone before it sees any airflow.

On slider down configuration, opening speed has very little or no relation with exposed nose or extra fold her or there.
I know.... this statement may raise many questions as opposite thinking is very common here in BASE world
However, the field testing showing that I am right. Again It is about Slider Down!! Not Slider Up (which is different story)
One and only thing what has great impact on opening is speed of extraction, design of bottom skin and brake settings, that is all.
Once the canopy bottom is spread out , the pressurization comes , but that is the second stage, which than has some connection with nose expousure..
...so, when thinking how to get canopy open fast, think about how to get extraction of the lines fast- it is very simple!!

hey robi, can you please be a bit more specific on those three points you made (1. speed of extraction, 2. design of bottom skin, 3. brake setting). what does it mean? what we need to do in order to have a fast opening? and what we have to avoid? thanks in advance and best regards, bernhard (will we see us at heliboogie?)

I think Robi is absolutely correct here. The brake setting issue can be a bit confusing though. I think that shallow settings cause quicker openings than deep brake settings.

shallow settings cause quicker openings than deep brake settings.
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this may happened but that depends on the delay. it is mainly subjective impression due the opening shock...
when we talk about go-throw jumps ( very low object ) Brake settings should be right , just near but not at stall point, but again that point is again different and depends on weight and taken freefall delay.
Usually it is good to set brake settings on 1 second as that is the most common delay taken w slider down ( even the most jumpers say they took three or four )

ok thanks.

most of my jumps are mesh slider up and i do know that shallow settings cause more rapid descent of the slider, hence a quicker opening. i don't like very hard openings so i always pack slider up packjobs with deep brakes. Most of my delays are from 3 seconds to 12 seconds.

 
Okay, so if two jumpers, who have the same canopies, PCs, and weight go and throw from 200 feet, will the one who uses a shallow setting be open higher or have more flying time?

do either of them have a mustache?

Do they have vents?

Jumper A is using shallow settings, has a handlebar moustache and is radder than the other jumper. Jumper B is using shallow settings, no moustache, and not rad. Other than that all else is equal.

Originally the variable was deep vs. shallow.

But now you changed the thought
experiment to mustache & radness.

So use whatever break setting you
like, grow some facial hair, continue
being rad, and you are all good

Can you explain your reasoning?

Can you explain your reasoning?


I sink quickly on my Troll with vents
whenever there is a touch brake input.
Hence deep brakes on a vented wing
equals faster descent in my mind.

One comment, though I expect it's got nothing to do with where the tailpocket is. Watching a bunch of static line video some years ago, we realized that the usual packjobs give the canopy a rotation as it leaves the pack tray. I've attached an image here, built from the video. Note that the packjob is s-folded vertically because the jumper has done a "step off" style exit, but that the same thing would happen if the jumper were horizontal at deployment.

The rotation causes the canopy to be somewhat "nose-down" when it starts deploying. I have my doubts about this being a major effect in deployment, but thought I'd note that the canopy has dynamics that can be influenced by how it is packed in the container, and is not simply "pulled straight away".

I'm confused by your diagram.

Are you saying:

1) that the canopy is tilted forward when it leaves the pack tray, or;
2) that the canopy is tilted forward when it reaches line stretch and begins inflating?


I'd be curious to see the video. I'm having trouble visualizing a canopy at line stretch canted forward as you've drawn it, and with the locking stow in place, I think the inflation before line stretch (when I could visualize it canted forward) is going to be negligible (since the stow is binding the base of the canopy together.

Both, sort of. The canopy is (on the whole) rotating forward as it leaves the pack tray, owing to the geometry of the thing. When it hits line stretch, this rotation is conserved, and the whole packjob is extended and tilted forward maybe 20 degrees by the time it starts to inflate. As you say, the canopy hasn't inflated at that point, and if it had any effect, it'd be due to the way that the packjob is presented to the relative wind.

I'll see if I can dig up some representative video.

I think you may be overgeneralizing based on your experience. Remember that the "deep brakes" on any canopy are relative to the suspended weight. That means that one jumper's deep brakes might be shallow to another, and that it's very difficult to compare "deep brakes" across canopies.

All else equal, I'd expect the unvented canopy with shallower brakes to inflate slightly faster, because it hops forward a bit more to scoop air into the nose inlets. The same reasoning is true for the vented canopy, but a lot less important to it's overall inflation (because the bottom skin vents generate a more dominant portion of the inflation, reducing the relative influence of the nose inlets).

you may be overgeneralizing based on your experience
you may be overgeneralizing based on your LACK OF experience

Fixed it and completely true

I just use this super cool method that came in the CR manual for my BlackJack. Kinda like 98.7% of folks pack. It doesn't suck and works most of the time.

When it stops working I'll put the tail pocket at the top w/2 full line twists in.

I've attached a side view on one of the jumps where we first noticed this. This one's quite extreme, and in addition to the angular momentum the packjob picks up while leaving the tray, takes contributions from the fact that (1) the jumper is quite flat for a PCA jump due to an acrobatic exit; and (2) he's rotating slowly, so that the packjob picks that up as well.

You can see that the packjob rotates further than the jumper, though, moving through maybe 45 degrees while the jumper rotates through maybe 20 degrees. It's that extra 20-30 degrees that I've seen on a lot of static line jumps, even where the jumper drops straight off of the object in a vertical position.

As I say, I doubt it has much effect (the opening on this jump was completely unremarkable, despite the huge lean on the packed canopy as it comes toward line stretch), but I've always been curious about whether one could pack a canopy such that it had no angular momentum (as in the diagram earlier) just by virtue of being pulled out of the container.

I guess if you see line twists putting the tail pocket inverted at the top of the container, then have fun.

Of the pack jobs that I've done with it inverted at the top, on heading opening. Solid.

Shallow, deep brakes...what ever your pleasure. Isn't the point in the brake setting a reefing method to assist with depolyment?.

So when you open up your not into full flight, but not at a stall?

Sounds like people are trying to build a rocketship to the moon when all they wanted was to go to the store down the street for a pack of smokes.

Still don't understand how it works.

This is a nugget though and I myself often end up doing this:

Where do the risers end up when you invert the tail pocket?

at the exact same place in the pack tray.