Trim, buffeting, dangers?

[skyhighkiy 0]

ok, sorry, I did a search for this and didn't find anything (I'm probly just not very good at searching the forums)

anyway.

My canopy is out of trim and the brake lines are too short (no bow)

when I pull both fronts, regardless of whether or not I have toggles in my hands (tested high) the canopy buffets.

what are the potential dangers of buffeting? I can feel the lack of tension in the line when it bounces, but what can happen?

Thx.

BE THE BUDDHA!

[AggieDave 6]

Here's the trick, is the canopy out of trim or did the brake lines just shrink a bit? You can very easily adjust your brake line length, but I would highly recommend having a rigger show you how to do it properly the first time you try (as well as show you how to finger trap the excess line).

Now, if the rest of the canopy is out of trim, you might want to get that fixed (new lineset), since it'll start effecting the openings and flight.

As for the bucking canopy, it can be a serious thing, especially if you're cranking out a hook, but hopefully at 89 jumps that's not how you're experiencing the bucking.

Just go ahead and talk to your rigger about lengthening the brake lines (letting them out) and see what that does for you.

A good rule of thumb is to only lengthen an inch or so (you don't want to lengthen out a long way) per jump and keep adjusting as needed.

--"When I die, may I be surrounded by scattered chrome and burning gasoline."

[Spizzzarko 0]

Talk to your rigger. DO NOT put your canopy into intentional buffeting. That is all.

[SkydiveNFlorida 0]

If there isn't much slack left in the trap of the lower lines, you can just have new lower brake lines put on, rather than entire new brake lines. I did that with my first canopy. I don't think it costs much, either (it was done for me as a favor by a friend). Prior to that I was getting a lot of bucking in riser turns... when your canopy is fighting you, it'll probably win.

Angela.

[SkydiveNFlorida 0]

Quote

when I pull both fronts, regardless of whether or not I have toggles in my hands (tested high) the canopy buffets.

Just reread... That's odd. That wouldn't be a brake line problem if you've let your brake lines go, then. When you pull fronts w/o holding your toggles (which I have no idea what you'd do that for), you are obviously not pulling your brake lines. Maybe your canopy is severely out of trim, that or the brake lines are so short that you're actually flying in brakes at full glide. I would talk to a rigger who can inspect and maybe test jump it.

-A

[ramon 0]

Dave and Spizzarko are right, get a re-line. Ask the person doing it to not "sew" your brake lines but to tie a knot so that you can let the brake lines out a little if you need to.

Then if under your canopy in full flight up high if you look at your brake lines with no toggle pressure there should be a bow (i.e. they should not be pulling tension on the tail in a full forward flight).

If you pull double fronts to simulate getting drive in higher winds and look up at your canopy it should not buffet...if they do let the brake lines out like 1 inch.

Properly trimmed your canopy should allow a smooth double front.

After you find a sweet spot where your canopy is not buffeting, you can get a rigger to sew your lines if you wish. On some canopies you may have to let it out 2 inches (if the canopy gets tension in the tail when you do this, but does not buffet that is fine).

Experienced swoopers often let ther break lines out much further as they not only wish their canopy to not buffet, but to reatain an efficient shape when they perform front riser turns. Not only do they not want their canopy to buffet but they want it not to pull down the tail (adds drag). This is good for small canopies swooping but maybe not ideal for a typical jumper.

I have a VX where the brakes are let out about 5 inches, the canopy does not buffet or even deform when I pull doulbe fronts...but that is for swooping. And I have to flare past my hips to get a full flare.

I also have a PD vengeance and when I pull double fronts my tail is deflected, but I have no buffeting, so I leave it (this is my "need a safe parachute" canopy). It is easy to get a full flare on this one and it flies perfectly.

If this does not help talk to a rigger (prefferably one that is up on newer canopies).

ramon

"Revolution is an abrupt change in the form of misgovernment.", Ambrose Bierce.

[skyhighkiy 0]

Hey guys, thanks for the info...but my question was really regarding the dangers of buffeting.

My self-diagnosis in the air (with the advice of the riggers I know, on the ground)
let me know that yes, my brake lines are too short because (as stated in first post) there is no bow in them
the canopy is out of trim, when packing, 1st A (outermost) is about an inch and a half to 2 inches above the 5th A (innermost) and the whole group cascades, rather than being even.

skydivenflorida, my reason for pulling fronts up high w/out holding toggles was to take out the variable of pulling the toggles down to the dive loops (i.e. testing trim, rather than taking the chance of testing trim and brake line length at the same time.)


thx for fingrtrap info, I need to ask about that.


b.t.w. aggie, I'm interested, how does it affect openings? does itmake them harder? cause I've been getting whacked really hard as of late.

BE THE BUDDHA!

[BrianSGermain 1]

Quote

My canopy is out of trim and the brake lines are too short (no bow)

when I pull both fronts, regardless of whether or not I have toggles in my hands (tested high) the canopy buffets.

what are the potential dangers of buffeting? I can feel the lack of tension in the line when it bounces, but what can happen?

Thx.

The risk is that your canopy could collapse. The chordwise oscillations can increase in amplitude such that the A-B cascade point can drift aft enough to make the nose of the canopy dive at you, and fly at a negative angle of attack, and possibly depressurize the canopy. This will cause an immediate increase in the rate of decent, and will take control out of your hands. If the ground is nearby, you are toast. (Speaking from experience)

It will take you about five minutes to make the change. Please do it now. In the time that it took to debate this issue, you could have irradicated the problem.
+

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[skyhighkiy 0]

thx

BE THE BUDDHA!

[AggieDave 6]

Quote

b.t.w. aggie, I'm interested, how does it affect openings? does itmake them harder? cause I've been getting whacked really hard as of late.

That's a classic example of what happens when your lines are out of trim.

Get a rigger to do a quick check on your line trim this weekend (he/she can do it by laying the canopy out like a flat pack, to check the lines against each other since the groups won't uniformally go out of trim).

--"When I die, may I be surrounded by scattered chrome and burning gasoline."

[BrianSGermain 1]

Quote

Quote

b.t.w. aggie, I'm interested, how does it affect openings? does itmake them harder? cause I've been getting whacked really hard as of late.

That's a classic example of what happens when your lines are out of trim.

Get a rigger to do a quick check on your line trim this weekend (he/she can do it by laying the canopy out like a flat pack, to check the lines against each other since the groups won't uniformally go out of trim).

This is but one example of what can happen when lines go out of trim. The result is mostly based on the specific parachute design. Some canopies will open better as the brakes setting gets deeper, while others will get harder. Some will open more off-heading, others will be more on-heading. Generalizing concepts in parachute design is the best way to be proven wrong.

The best thing to do is to establish what the brake setting is when a canopy is new, and then watch it evolve. When the brakes get shorter than the "A" lines, it's time to do something about it. Just compare the shortest brake line to the center cell lines when the brakes are stowed.

For more on this and other maintanence issues, please read: The Parachute and its Pilot
+

Instructional Videos:www.AdventureWisdom.com
Keynote Speaking:www.TranscendingFEAR.com
Canopies and Courses:www.BIGAIRSPORTZ.com

[AggieDave 6]

Brian,

Thank you for the correction. I know you've forgotten more about this stuff then I've even learned in my nearly 5 years in this sport.

--"When I die, may I be surrounded by scattered chrome and burning gasoline."