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Just had a thought today...Probably doesn't actually mean anything and I haven't elaborated on it too much, but I just thought I'd run it by you guys.

I'm a grad student in Physics...just so you know where my motivation is coming from in thinking about this. Theoretically a parachute deployed the same way every time in the same conditions with the same packjob, yadda yadda...should open the same way (or at least nothing so major as a 180 or linetwists or worse)...but obviously that's not the case .

I've been exposed a lot recently to research that focuses on bifurcation, stability analysis, chaotic systems, etc...and I think that there is a LOT of pertinent information there for BASE gear. What if there are certain components of the inflation characteristics of a canopy that are susceptible to similar dynamics? PC hesitation and burble as an unstable equilibrium (obvious) or maybe even modeled as a type of chaotic dynamical attractor (the fluid dynamics and their effect on the PC I mean).

IMO BASE manufacturers might benefit a LOT from that type of modeling. If you can successfully model something like that then often times you can figure out what criteria / initial conditions / etc can be changed to influence the dynamics in a favorable way.

Physicist + Mathematician + BASE gear specialist + wind tunnel + high speed camera + computers w/ fluid dynamic modeling software = profit?

EDIT: Also, I've seen people do slow-scale modeling of high airspeed flows using a liquid, dye, and a nice, controlled setup (something like this http://www.youtube.com/user/Fluidmechanicsvideo#p/u/1/ua2k1MRIK4o ). I wonder what would happen if you worked on simulating parachute openings like that...*shrug* would be awesome to watch if nothing else =D

I'm sure a lot of testing has been done on ram-airs already. They've been around for a long time now, relatively speaking.

There's a lot of variables in BASE, and a lot of these variables are controlled by the jumper and not the gear. To expect a human to be able to eliminate variables like PC toss speed, direction and rotation, body orientation, relative wind, turbulence from clothing etc is expecting too much :)

But hey, go crazy. If you think there's a lot of benefit in doing something, let the market be the judge of that. There can never be too much research made.

It's easy to predict what you will see: A Big Mess. Imagine that instead of a nice steady wing you put a folded grocery bag inside the tank. Now start moving your hands randomly in front of it to simulate the burble and see how nice green lines of dye instantly disappear and the tank is now filled with swirling muddy liquid.

After that, the real question becomes, "Why the hell it opens on heading most of the time?"

Profit?

How much does wind tunnel time and good CFD cost? How many rigs do base manufacturers make?

C'mon man. Gotta cut back on all that acid you must be on. I know you physics kids are doing all kinds of weird stuff... As for the testing, benefit could theoretically exist, but far too many dollars down the road to really see the profit at this time probably.
Also, it sounds to me like you're just adding more complications for yourself to consider, and safe BASE is kind of about keeping it simple, right? To be honest, you sound like you haven't jumped yet to be so questioning. Nervous about 180s? BASE isn't for the uncoordinated or weak-stomached.
Let me know when you strike it rich one day and actually get to work on this, you know, right after you find that oil in the ground behind your house.

I think your idea is really good, but you're not asking the right audience. Apply it to skydiving instead to solve the line-twist/diving canopy issue and I think the base community will make use the benefits from your analysis and apply it to base themselves. Slow motion video of base canopy openings freak me out. Best not to look!

For as much as I would like to use my background in econometrics and run regression analysis on BASE jumping you should first realize there are several specification errors with trying to model such a vastly complex chain of events that leads up to your chute deploying.

As many have said, watching the canopy deploy is scary. Then there's the factor of maybe it got bumped on a climb to somewhere that shifted the canopy a little bit causing it to open awkwardly. Maybe it was packed symmetrical according to the eye but one spot was tighter than the other and it pulled it over due to motion.

The problem with a wind tunnel is that it's a perfect environment. It's too consistent. Base jumping isn't done indoors, it's done in the hearts of canyons, valleys, urban environments, etc. The wind streams are almost impossible to predict that accurately because of all the varying factors. I can remember spitting off the potato bridge and watching it fall smoothly to the ground. 10 seconds later I spit and it swirled around before taking a straight path again. There was almost no noticeable difference in physical wind speed.

So yeah it would be cool but it would take a lifetime to come up with all the u variables that may alter the desired opening of a canopy.

Next time, don't buy apex

Fluttering phenomenon are the most complicated and least understood aerodynamic processes in nature.

The is a group that does compressible CFD to understand parachute openings and flight. It includes material properties like deformation and elasticity. The Army funded much of this research. Check it out: http://www.tafsm.org/

For a round parachute:

http://www.tafsm.org/PROJ/AS/MDCM/

Note that these simulations require vast computational resources that are not at all cheap.

http://www.tafsm.org/PROJ/AS/

Just a thought on how complicated and chaotic the factors in heading performance really are:

I think the opening is very chaotic and also think it is miraculous how great the heading performance on base canopies is. I saw this video (link below) yesterday in which Todd from Apex explains the reasoning behind the Multi, which is supposed to prevent center cell stripping and improve heading performance, but atleast to me it seems like jumpers have not bought into it that theory much since majority of people do not use it. It is a brave effort and in theory its great, but the jumpers would all use it if it was a certain improvement to heading performance.

I tried to find it on youtube but it seems its only posted on Facebook: https://www.facebook.com/...?v=10150445121331180

Kerkko
BASE1184

I had almost no serious off heading opening in hundreds of jumps using a multi. Most of these jumps were mesh slider up, delays from 2 seconds to terminal.

Your body position at pull time must be spot on, just like your pack jobs!

Like I said, if the evidence was seen as conclusive by basejumpers, everybody woud be jumping the multi. Opposite example would be something like the tailgate, also by Todd I believe, no one in their right mind jumps slider down without one.

I have one jump with Multi, thats it. I'm not saying it isn't great, just saying that most jumpers don't believe it helps.

Kerkko
BASE 1184

I don't believe the types of jumps I regularly do are that common. Most other people's jumps I believe are slider down or near terminal. I jumps canopies with and without the multi. I still get much better openings on the ones with the multi. The multi doesn't seem to help slider down.

Thanks for the info =)

I just re-read my post this morning...I should smoke less weed before I get on the forums

Man, you are spot on to keep thinking about such problems and I applaud you. A curious critically thinking person is more of what the world needs. Don't sweat it. Please keep posing such questions.

Yep. Here's a pic for the OP.

Edit: I know its not the controlled test tank thing that yall science nerds where talking about, but it still shows the OP that it comes out messy even if it goes in clean (just like sex).

im not sure whos opening that picture is of, but whoever packed that rig seems like a real mess of a person, who is most definitely going to break a nail soon on one of his BASE jumps!!!!!!!!!!! im appauled and nauseated!

dick. You on the west coast yet, or still in sin city? Call me, I'm trying to book a ticket.

sin city till tuesday, then LA, then up to san fran a week from today brother! im gonna book a trip to seattle in probably april for some flicks and a flystyle tour.... come down before then!