Slider-Up Heading Performance

[Zennie 0]

Following Tom's suggestion...

Quote

I've been fighting my Ace since Day 1 to get it to open on-heading slider-up. Slider-down it opens just dandy, but slider-ups have been giving me consistent 45deg (+) off-headings.

460 and I have been kicking around theories, such as tail-rolling/folding techniques, but one thing I always do is attach a rubber-band to the left inner C-line and then take a bite of slider mesh to keep it up on the stops.

My last jump was off-heading veering to the left and thinking back I'm pretty sure most, if not all, of them have been in that direction.

So I'm starting to wonder if this might be the real source of the problem. Perhaps by having the slider rubber-banded to one side I'm creating asymmetric tension and inducing a turn in that direction.

Then again I could be all wet.

And to answer Tom's question these are generally 5-10 second delays. The last one was a 5 second and I probably had a 90deg off. I had one from 1900 where I wound up with a 180.

So yeah I'd like to hear some discussion on how people manage heading in a slider-up configuration.

- Z
"Always be yourself... unless you suck." - Joss Whedon

[TomAiello 26]

Are you certain that you are stowing the slider from the center (i.e. is the bight of mesh being taken from the exact center of the slider)?
I'm not sure if this would make a difference in practice.
In theory, if you take a bight closer to one side of the slider, the other side could expand more, at an earlier point in the inflation sequence (before the slider begins deploying). This inflation "head start" could generate an off-heading.
This line of reasoning would seem to fit the observed facts in your case. With the stow band on the left side, you are more likely to take your bight slightly left of center on the slider mesh, which might constrain the left side slightly longer, giving the right a head start, and generating a turn to the left. It sounds good in theory, but I've never seen appreciable evidence that this happens in practice.
Personally, I prefer to mark my sliders' exact centers, just to be sure.
Another thought: What kind of rig are you using? I've seen consistent off-headings on two pin rigs generated by closing technique. If you are using the leverage of the pull up cord to bring the side flap in when closing, that can twist the pack job a bit, and generate consistent off headings. So, if you're on a two pin rig, I'd look at your closing technique, as well. This ought to be less of a concern with velcro, and is pretty much not a factor with a Prism.
Yet another thought: how many jumps are we talking about? I generally ignore trends like this, for my own jumps, unless they are happening consistently over an intermediate term (say, 50 or so jumps).

-- Tom Aiello

Tom@SnakeRiverBASE.com
SnakeRiverBASE.com

[Zennie 0]

Quote

What kind of rig are you using? I've seen consistent off-headings on two pin rigs generated by closing technique.

I'm using a Warlock. I do tend to tug a little to getthe grommets lined up so that could be a factor. But why would my slider down pack jobs open fine if I use the same technique?

Quote

how many jumps are we talking about?

About 10 or so.

- Z
"Always be yourself... unless you suck." - Joss Whedon

[Diver23 0]

---------
My last jump was off-heading veering to the left and thinking back I'm pretty sure most, if not all, of them have been in that direction.

---------

A friend of mine has a brand new Ace which opened consistently to the left on sub-terminal slider up jumps. We still have not figured out what the problem is. He is using a two pin rig and don't uses any form of slider control.

Cheers

[jimjenningsmpa 0]

I was in Norway last summer and a friend of mine had his brand new ACE - jumping it for the first time. He did three jumps in a row and all jumps were a 180 off heading. He was scared to jump it and asked me to give it a jump to see if it was his body positioning that was causing the off heading. He bet me a bottle of Whiskey I would have a 180.

I obliged and packed it the same as I pack my FOX. Slider up - two wraps from a small black rubberband on each center C line for direct control of slider - a double wrap indirect control of the slider for backup in the event the direct control failed, and a double wrap of the upper control lines with masking tape. The jump was good up until opening. The canopy seemed to have a two stage opening. In the first stage the canopy pulled hard to the left as I was propped upright and instantly pulled the right riser to correct the offheading as it opened. The second stage of the opening was more the inflation and it opened slowly (IMHO) but on heading since I was yanking on the right rear riser. I did another jump and it opened fine - in 2 stages and too lsow for my taste. This canopy had excessive forward speed (IMHO) during flight and I would not want this if I was facing a wall. It did have a very nice deep flare. The canopy opened to the left - same as the 180 openings my friend had.

Another friend was jumping his ACE for the first time in Norway and he had an offheading with two line twists - to the left. Since then he has also had a terminal snivel jump. He is selling his ACE and test jumping the FLIK.

Those are my ACE/off heading stories. I don't believe direct control of the slider has any substantial effect on the opening direction. Mnay people have been doing direct control of the slider for years...

JJ

[Dd0g 0]

I am far from the only jumper who has suggested strongly that the Ace/Blackjack canopies have earned a reputation for bad slider-up openings. I believe these canopies - for whatever reason - consistently produce off-heading openings slider-up.

Further, I believe there is ample hard data after Petronas this year to back up this "hunch" that I've had for the better part of 9 months.

I don't want to beat a dead horse here, but I also don't want to sit on my hands. I've posted a somewhat-vociferous statement on the subject at the [ url "http://www.basejump.org]ABA website,[/url] in the forum section.

I a far from an authority on BASE gear, so take my opinions with a good bit of salt. They are just that, opinions. That said, I'd not jump these canopies slider-up with a hard object behind me. Period. I'll do lots of stupid things, but that's even outside of my own personal "stupid envelope."

Peace,

D-d0g

+~+~+~+~
But this, surely, was the glory that no spirits, canine or human, had ever clearly seen, the light that never was on land or sea, and yet is glimpsed by the quickened mind everywhere.

[TomAiello 26]

I doubt very much that CR is selling a canopy with a designed in left turn on opening. In fact, I think it would be very hard to design such a canopy. You'd have to purposefully create some weird assymetry in the design. And an off-heading resulting from the design would be the only thing I could think of that would create the phenomenon you're suggesting (that all Aces open off heading to the left).
Saying that CR has designed a canopy that opens left every time would imply that they (a) have some nefarious reason for wanting it to open to the left, and (b) are so good at canopy design that they can call an opening direction, based only on canopy design.
While I have been generally impressed with Adam's design skills, I don't thing they are quite that advanced.

-- Tom Aiello

Tom@SnakeRiverBASE.com
SnakeRiverBASE.com

[TomAiello 26]

Hi Jim,

Quote

I don't believe direct control of the slider has any substantial effect on the opening direction.

You were the first person to suggest a double direct stow (one stow on each center C, with both holding the slider) to me, sometime last year, when you were using that method.
Can you explain what you found when you did that?

-- Tom Aiello

Tom@SnakeRiverBASE.com
SnakeRiverBASE.com

[PhreeZone 20]

Turns in opening (at least skydiving wise) can be trim issues or even riser issues. If one corner is just a little bit longer or shorter it can change the way the canopies fly and open. I'd go over the trim and make sure the lines are all matched in thei size and that the 4 points of the risers are all the same length if you are thinking its a possible gear issue. Another possibility is Link size, if one is streched or something that affects things too.

Yesterday is history
And tomorrow is a mystery

Parachutemanuals.com

[flymysky 0]

>Can you explain what you found when you did that?

[jimjenningsmpa 0]

Quote

>Can you explain what you found when you did that?

One day I was packing in front of a guy who has a bit of experience rigging. I was directly stowing the slider using a rubberband on one center C attachment point. He suggested it would be just another way to keep everything symmetrical if I had a rubberband on BOTH center C line attachment points for stowing the slider. It sounded like a good idea theoretically so I did from then on. I packed this way for about a hundred jumps or so on my FOX. When packing this way it is sometimes difficult to get an even bite on each side of the slider, so I began to take one bite and double wrap both center C lines. It worked so I began to do it on all my slider up jumps and have been ever since - at least 200 slider up jumps - even lower airspeed slider up jumps - 3 to 4 seconds. The results have been good so far...