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Does anybody have any opinions on pilotchutes where each pie slice is its own unique piece of ZP fabric?

I'm aware that Asylum's Toxic also has the vents moved, something I can potentially see as an advantage. But I'm not convinced the advantages of more symmetric fabric loading are worth the introduced complexity of the extra seams.

I ordered a Toxic to check it out, but I'm curious what other people think. Not just about the Toxic, but about pie-slice based PCs in general.

Thanks,

Jaap Suter

I don't know a ton about it, but what has been explained to me is when they do the pie slice method it gives them the ability to line up the block and bias so that the material is as stucturaly perfect as possible. If the block is lined up incorrectly to the seems the PC will strech under load and probably oscilate.

Maybe you already know this and you are asking a different question, but if not, grab one of your PC's and look at the block pattern. If you poll from corner to corner it will strech, but from flat line to flat line it won't.

Yeah, that's what I meant referring to the "more symmetric fabric loading". I suppose I could have explained that better.

Part of me is imagining a pilotchute of which one spoke blows up. On a single-piece pilotchute, you'd probably generate enough drag still (albeit asymmetrically), whereas on a multi-piece pilotchute you now have a big hole across half your pilotchute, significantly reducing drag.

Now I'm sure Asylum (or any other manufacturer that makes PCs this way) assures me that the seams just won't break, but in a sport where the working of a pilotchute is the difference between life and death, I'm not sure if I want to tinker with a proven design.

That said, Asylum's QA has always been phenomenal so I ordered one and will see what it's like.

 

How they line up the block or bias relative to the rest of the pilot chute has no bearing on the structure of the material.


The ZP(or Low Porosity) material in the pilot chute stretches/deforms under load no matter how the seams are oriented.

The amount of deformation can be minimised by orienting the reinforcing tapes along the bias, as this is the direction that the material will deform in the most under load.Maybe you already know this and you are asking a different question, but if not, grab one of your PC's and look at the block pattern. If you poll from corner to corner it will strech, but from flat line to flat line it won't.

Why haven't pilot chutes evolved since they began as a circle of mesh and a circle of fabric? Does anyone disagree that pilot chutes/oscillations are a primary cause of off-headings?

Then why aren't pie-shaped, round-style PCs making an entry into the market? Besides being rounds, I don't think anyone would want to jump a round into the ID bridge if it had suspension lines as long as the radius of the fabric! Then why would PCs have to be so primitive and potentially trouble causing? Lets advance pilot chute technology next, unless someone has a better place to continue...

Why bother? It's too much trouble making them that way. The old para-innovators from many years ago used to have independent gores, but expense was no issue since it was military related.

My new "Pie Slice Pilotchute" (Actual name: Toxic) is ready for pick up at Asylum. They're already being made on a limited basis, meaning, you can get one, but there's a long wait time. They're definately more labor intensive. It's an impressive design and built rather nicely.

hmmmm....
i have a lot of PC ideas, not to mention a ton of sewing experience, and a fuckton of spare time these days so, maybe i will.

seen one in person a few times, and it is extremely nice.. like a mini tandem drouge almost, but lots of stitching involved.

Ummmm, just for the record- Toxic pilot chutes are not made to look like tandem drogues. The mesh and ZP are the same dimensions...

agreed... i dindt say that, and im not a rigger..

 
Making BASE PC's more complex in design for the short job it must do of opening and pulling out the Canopy to start it's inflation ? Will there ever be a perfect Hand Deployed PC. That sits in air-movement and Tows without movement ? The perfect human deployed PC is a pipe-dream. PC's these days really do a outstanding job for BASE and they are at there highest point of design and function especially the vented smaller PC's. designed for higher air-flow speeds.
The BASE PC has a important job but it's job is very narrow/specific in function. It must go-out, open, then pull-out. In a Very Short time span. All PC's move around somewhat in the air-flow and the job that the BASE PC does in Free-Fall is nothing in comparison to what a Drogue has to do especially in the long term designs of free-falls where it has a specific job to do that is more complex than just opening and starting the Canopy inflation sequence.
When everything is done right like symmetrical construction, distortion from tread tensions kept uniform throughout construction with proper Tapeing along with a centered Tow. The BASE PC tows strait with movement to a minimum. It simply does its short job very well and for me. I am pretty satisfied with what I am getting and seeing out there BASE jumping.
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There is also a huge flaw with this Thread. In comparing Drogue construction & BASE PC construction to promote better functional design and is flawed with endless for disappointments in the quest for the perfect hand deployed BASE PC. Flaw in comparing the design, there/SIZE - function/job, length of each in TIME used to complete it's designed job, air-speeds in which each performs it's designed job. Along with the basic one size fits all for Tandem and BASE uses specific sizes for a specific air-speed of ranges.
The quest to become more proficient in BASE is much more important than the quest for a perfect BASE PC.
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I would be more impressed with an auxiliary custom system to release my spandex pouch and launch the pilot chute away from me in case I was having difficulty with the extraction.

I can't imagine that PC technology is at a standstill just because it has reached the top of today's technology and ideas. A pilot chute is perhaps the simplest and most critical aspect of the entire operation.

If the pilot chute is oscillating because it is a piece of crap, then your badass canopy with your 2 hour Building packjob is pretty much compromised.

I don't believe that a pilot chute just needs to open at pitch time, pop pins or velcro, get to line stretch, and then it is done. It needs to be a ultra-stable, ultra-reliable, non-oscillating, and pull in the desired direction. (UP!) Kind of makes you think of a miniature water round or Army round.

The canopy when it is coming off your back isn't a canopy. It is a bunch of nylon folded and pressed together, and the direction and force of the pilot chute pulling on the center of the topskin is a EXTREMELY critical time in both the lives of you and your canopy. Simply, if it isn't pulling straight up, your canopy is going to be influenced in that direction.

I am not a rigger, manufacturer, or any of that stuff. I just love to jump and watch videos if there is any light. But a significant percentage of the off headings that I have watched are due to the packjob coming out perfectly straight and on heading- but pointing straight at the wall. The pilot chute comes out wobbling, pulls the packjob out as expected, twisting and oscillating, and the packjob gets turned around at the mercy of a PC that is pulling anywhere but straight.

Pilot chutes can be improved. They have been lately, but I used to have a 32" PC that I use for slider up that gave me 180s most every time. And when you watch the videos, it shouldn't surprise you. It looks like a propeller behind me, and the canopy with a nice packjob just goes where it is pulled. In this case, anywhere but straight. Replaced with one that doesn't suck, I have great, solid openings.

Now the question is how to make PCs that are a little more than a disc of mesh and ZP. If need be...

And Ray, I would be really interested in learning your opinion of how many off headings are the result of PC oscillation. And this isn't just limited to oscillations- why do jumpers still accept that PCs just don't inflate sometimes, or hesitations are just part of the game?

this has probably been thought of already, and i'm willing to bet that there's a good reason for this not being done, but i'm bored so here goes anyway:

To decrease/eliminate PC hesitations, what about introducing some kind of rigidity or memory to the design? for example, a thin, flat, flexible length of plastic sewn into each radial reinforcing tape? I'm talking only a slight amount of stiffness, so upon extraction the PC spreads open a little bit rather than staying stuck together until the airflow pulls it apart? But not stiff enough to cause bridle entanglement issues.

Has anyone tried this, and if so, what problems did you run into?

That's the way my specially designed 49 inch pilot chute works. Very stiff tapes to cause it spring open.

Have you seen any others like it?

Has it worked well enough that a very light stiffener would be practical/reasonable/efficient/a general good idea?

If this is just another good idea that is a bad idea in practice, thats all good. But it might have saved some lives recently.?

No, I have not seen others like it. It was custom designed by my friend Walt Appel. I had no problems with it, but I was always going hand held.

Maybe something like the image I attached, so you could stow it too. Excuse the penmanship, it wouldn't let me use the text option in paint.

Even if it is a very light springy plastic, it still might way the PC down though and cause hesitation.

Any nick on that plastic is likely to capture the mesh and prevent the pilot chute from inflating. I suggest more rigid external tapes.

..."I am not a rigger, manufacturer, or any of that stuff. I just love to jump and watch videos if there is any light. But a significant percentage of the off headings that I have watched are due to the packjob coming out perfectly straight and on heading- but pointing straight at the wall. The pilot chute comes out wobbling, pulls the packjob out as expected, twisting and oscillating, and the packjob gets turned around at the mercy of a PC that is pulling anywhere but straight. "

..."And Ray, I would be really interested in learning your opinion of how many off headings are the result of PC oscillation. And this isn't just limited to oscillations- why do jumpers still accept that PCs just don't inflate sometimes, or hesitations are just part of the game? "

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I wonder what the percentage of those osculated caused deployment Canopy twist was caused by.
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1- Pilot Error in non-centered Bridal attachment ?
2 - Simply not keeping good symmetry or distortion non symmetric due to bad-non-consistent Thread tensioning on Seams and Tapeing ?
3 - Pilot simply does not know his PC. what habits good/bad or unaware or unable to identify a plan and simple un-balanced Pilot-Chute ?
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I don't know if it's a matter of just total acceptance of the VERY rare PC total malfunction. PC's do hesitate on inflation this is a documented fact and Given enough altitude most any un-inflated PC will most likely inflate. The biggest risk that must be accepted is that the human error in judgment on the mechanics of Packing and the Grasp & Pitch out plus the human element in the Manufacture and QC is the biggest risk any BASE jumper MUST accept without choice. pilot/human error is the big killer. not your PC
I feel that the level of performance I get when I throw my PC to the wind is Acceptable and Satisfactory. I am happy with the level of design at this point in BASE.
Would not the manufacture of a much more labor intensive and complex PC design be more inclined to the human error not mechanical malfunction ?
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There's an interesting physics problem: double pendulum. "A double pendulum is a pendulum with another pendulum attached to its end, and is a simple physical system that exhibits rich dynamic behavior. Above a certain energy its motion is chaotic."

Extracted canopy and PC at bridle stretch make a double [inverted, driven by drag and gravity] pendulum. Could it be that some PC oscillations can be caused not by asymetry of the PC, but by chaotic double pendulum effect? (A recent antenna strike in Russia, when the properly centered and symmetric PC wildly oscillated and caused 180, is one example.) If we can figure this out, then perhaps this tendency for chaos can be reduced by chosing a certain ratio of bridle length to line length and PC weight to canopy weight? Kind of avoiding the resonance frequency.

See the attached animation. Looks familiar?

Yuri

Edited to attach an animation.

Wow. I never though resonance frequency would have anything to do with deployment, but that is a sound theory.

but then again, its not really a double pendulum system until linestretch, is it?

> That's the way my specially designed 49 inch pilot chute works. Very stiff tapes to cause it spring open
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Would you mind posting (or PM) pictures and/or drawings of that special PC, please?

 

There's an interesting physics problem: double pendulum. "A double pendulum is a pendulum with another pendulum attached to its end, and is a simple physical system that exhibits rich dynamic behavior. Above a certain energy its motion is chaotic."

Hmm. I can tell you put a lot of thaught in to that.

As did you. He's right actually. F-111 made pilot chutes are more stable than their ZP counterparts.

I was mainly replying to "No need to be afraid of a little porosity".

Don't you get drastically more pull force from ZP. Would you have to use a 60" F111 PC to compare to a ZP46" pull force, even if it's vented.

I'm pretty sure I have heard other benefits to ZP as well.

The problem with going to F111 is that you gain some porosity, which makes the pilot chute more stable, but at the same time it also produces less drag. An F111 pilot chute is not optimal because it's letting air through everywhere. A better design would be a pilot chute whose porosity is controlled so that it produces a maximum of drag, but also lets air through in just the right places to stabilize. That's the idea behind a zero-p pilot chute with an annular vent.

Michael

lets see....
many thousands of jumps under study...hundreds of jumps of personal experience using F111...and I'm still here! Never had an object strike attributed to F111 pc. Problem is nobody has adapted it because of this fallible fear of "unwanted freefall." F111 is bulletproof! Can be evidenced by a 36 F111 I sold (it had 100+ jumps before I got it and jumped it for about 100 jumps and numerous counts of water exposure). It is fear that causes oscillation and thus death

THE DEATH MONGER

I'm certainly not saying using an F111 pilot chute will kill you. I use them, too. I'm just saying better solutions are possible.

Michael

 
How about a hybrid PC with both fabrics, ideally combined in a way to capture the benefits of both? Perhaps an inner circle of ZP and outer circle of F111? Just throwing ideas out there.

You're right, until linestretch it's more like a single pendulum with the suspension point (PC) able to oscillate due to feedback from the suspended weight (canopy).

When the suspension point moves with the frequency equal to the natural frequency of the pendulum, a resonance occurs. The system begins to oscillate with high amplitude.

The period of oscillations of a L=9ft. pendulum is T = 2*Pi*sqrt(L/g) = 2*3.14*sqrt(9/32) = 3.3s.

What frequency the PC oscillates at? Although it's more chaotic motion rather than harmonic oscillation, it still has some characteristic frequencies. They depend on airspeed, size, construction, etc. If the PC oscillates with the period of 3.3s, then we have resonant coupling between the PC and the canopy, which can cause an offheading.

If we can make the PC oscillate slower than the canopy does - slower than 3.3s - than this energetic coupling will be broken and onheading performance will improve.

One way to make the PC oscillate slower is to use a vented PC. It inreases the "effective mass" of the PC and slows down the latteral motion.

Will a longer bridle make the PC oscillations slower? Yes, but the canopy oscillation will be proportionally slower, too, so it won't kill the resonance, although the onset of resonant oscillations will be slower and the canopy will twist less.

Anyone have experience using substantially longer bridles, e.g. 15ft?

Don't we all at least agree that there is a lot of improvement that we can find with current pilot chutes? And PCs are a current weak link to a relatively solid modern setup?

ask the real yuri base... or do some more equations

Yuri (outrager) used to use a 25 foot bridle! There are more potential problems with this setup than there are advantages.

No, I don't think so.

Properly made F-111 and ZP PC's will exert almost exactly the same drag force. The air has to vent out of both of them--it just vents out differently. With an F-111 PC, it vents out through the skin of the PC. With a ZP PC, it vents around the skin of the PC (over the skirt or through the vents).

I once took a couple of F-111 and ZP PC's and tested this (I had doubted that it was true when Anne Helliwell told it to me), and it really did turn out this way when I drag tested them with spring scales.

" Don't WE ALL Agree " - The PC is the Current WEAK LINK. to a relatively solid modern setup?
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NO, WTF , have you not been reading what I wrote ? I am just to tired tonight to get into this Biggest conceived piles of shit tonight & one of the most fucked-up statement I have ever read. so I will stop this right there.

"Fact" The Pilot-Chute is one of the MOST reliable things that ALWAYS Works. Next to. The Canopy will ALWAYS Inflate after extraction.
You might want to re-think and get back to the Web. BASE jumping in a few years.
(just my opinion) There is NOT Ever to be a huge breakthrough in PC's like the perfect magical Sky-Hook. There is not much more improvement left you Can & Will do to the modern BASE PC. The only thing left to be done is small refinements in design. That will maximize and capture what little efficiency is left in drag and balance of movement.
The Pilot-Chute is not the weak-link, the most important thing, the biggest key piece of equipment, The one thing to FEAR the most in BASE. All PC's now & in the future. Will work and Look and Act just like the PC you though out into the Air yesterday. All a PC has to do is One-Short-Quick-Job. To pull-open and Drag-Out a big pile of fabric to inflate in a half-assed orderly fashon. After that it is up to the Pilot, "YOU" the BASE jumper to do his/her job.
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Some of the BEST Pilot-Chutes I got. Are the oldest & most used over my life. I have a firm belief that all New pilot-chutes must be broke-in. Life of the PC does not start on the first Pitch after it leaves the Loft. They must be used and forced to form and take shape after they come off the Sewing Machines. Thread and fabric weave must be slowly forced to take shape/stretch to a flowing end result over some PC packing & free-falls. After you get some jumps on the PC then you can judge how it tows and feels. Its got to be broke-in SLOW. You got to get to know them.
Don't be Scared. Take some slow quality time & Have a long and lasting relationship over many years with your PC. ...
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Holy hell, Ray... You finally lost it.

Come visit us down here and we can arrange some... therapy. Lots of cool objects to play with.[;)

> You're right, until linestretch it's more like a single pendulum
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No. You are wrong. BEFORE line stretch there no pendulum nor anything else. BEFORE line stretch there is no physical connection between jumper and parachute. BEFORE line stretch, non-stretched-lines CANNOT and DO NOT transmitt anything, nor forces nor movement nor momentum nor anything else. BEFORE line stretch, parachute is "simply" a piece of cloth trailing up there, completely indipendent from jumper's body.
Immediately after line stretch, I agree that exist two pendulums, parachute (through stretched lines) transmits forces to jumper etc etc.

What about bridle stretch? As soon as the pilot chute reaches bridle stretch the system seems like a single pendulum until line stretch when it becomes a double pendulum. Especially when you watch some bridge day videos of a dbag coming out.

Nerd.


One unfortunate person did, see the list.

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What ? . you don't talk to your pilot-chute ? I know your smarter than that.
I suppose next you will be telling you don't have an intimate understanding and long-tem relationship with any working mechanical BASE component in Either Hardware or Fabric ?
No relationship what so ever in the way that each mechanical part works and interact with each other. As well as the way those parts treat and interact with you on any given BASE jump ?
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Huh? I don't recall anything THAT long, even though some of the gear of my first couple of years was rather interesting

bsbd!

Yuri.

Don't worry. That is his usual response. He has many days-weeks that he can not remember and account for.
short-term memory loss.. 'cough cough' buzzzzzzzzzzzzzzzzz. .....
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I just don't get it… Why should we settle and believe that the PC cannot be improved?!?
Of course, jumper skills are more important than improving the PC, but why not improve the PC if possible??

The parameters we have to play with are atleast these:
Porosity of the topskin fabric (F-111/ZP), vents, diameter of topskin vs. diameter of mesh.

We need some facts on the table, and I don't have enough jumps to know, so to you with experience on this:
1. At what airspeeds does the oscillation mostly occur? 0-2s? 2-4s? 4-7s? 7+s? Let's pick the corresponding size(s) PC and experiment with that one.
2. I think what Tom Aiello said about the drag of F-111 vs. ZP is very interesting. Anyone want to measure the drag at various windspeeds for similarly sized F-111 and vented ZP PC's? If F-111 really makes a more stable PC, then this would be one of the first things to find out.

How do you know??? I don't seem to remember you...

bsbd!

Yuri.

hmmm...
what problems do you want corrected?

at some point in becomes a cost/benefit situation.
what knarly situation exists such that you want to pay 3x as much to correct?

(every additional seam on a pc can create dissymmetry and consequent oscillation.)

so what needs fixing? are they too expensive?
please define a problem to solve before requesting facts.

I was thinking that PC oscillation is a problem, and as far as I’ve understood, PC oscillation is believed to be a main cause for offheading when everything else is done right (good body position, no winds, good packing, canopy doesn’t snag on the tray).

But you have a good point: How often does this actually lead to an offheading more than, say +/- 60 degrees? 1:100, 1:1000? I guess it’s a personal decision what odds are ok, if we’re ever able to say what the odds are.

And I agree that cost and cost vs. added benefit may in practise be showstoppers, but we won’t know that before we know what the improved design is (if one exists).

So why look for a new design if we don’t know how big of a problem PC oscillation actually is? How would we verify the new design? How many jumps would it take? How about all the other factors that affect heading? Sounds like we would need a lab set-up. A new design may introduce new unforeseen problems…

But then again, how many of the modifications that have been done sofar are based on solid numbers? I think most of them are based on subjective observations and good ideas. I mean, how much evidence do we have that snagging on the corners of the pack tray is a problem? (With wingsuit, just arch before deployment. If you have head-down deployment, what are the odds of offheading more than +/- 60 degrees due to the canopy snagging on the corners?) But I like the _idea_ of dynamic corners. (no disrespect towards the manufacturers here, I think this a part of the sport)

Anyone have an opinion of what the odds are that PC oscillation alone will result in an offheading of more than +/-60 degrees, using a vented ZP PC?
Anyone who likes the idea of a PC less prone to oscillations?

"when everthing else is done right."

I think you'd get better results convincing people to get better at the those other factors you mentioned. too many want the easy way out and choose not to put effort into what they CAN do.

as you mentioned, if you can't quantify the problem, you'll never be able to judge that a fix works.

as for me, redesign the pc. go for it. but I'd rather see people focused on what is killing people.

Does anyone have pics of Asylum's Toxic P/C, or another example of a Pie Slice P/C?

hookit does, he's just slow to post it.

Is that the newer version of the bridle attachment point, which has the loop made out of an extension of the apex-pull-down-line?

Yes it is.

I've got three of them in use for FJC's, so I've got a pretty large collection of daytime video if you want to see it.

Oh sorry. I meant 24 feet!

It's about time someone that has a Toxic or a few mentions it.

Any opinions yet?

Here's a picture Marty sent me.

First of all, Yuri you have way too much time on your hands!

I guess I wonder if it matters so much, the oscillation that is, because by the time there is enough resonance, that is right at or a split second after line stretch, your center cell has been presented to the air... that is your heading has most likely already been established...

I don't think all this mental masturbation will result in better PCs or less off headings.

I'm with Ray on this one...

T.

You say that like masturbation was a bad thing.

Michael

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Those look Pretty

I can say for certain that not thinking about the gear is extremely unlikely to improve the gear.

To borrow from another thread: our greatest defense is that squishy thing inside our helmets--especially using it before committing to the jump.

When I step off the edge, I feel overwhelmed with the gratitude to the Founding Monkeys who started mental masturbation 30,000 years ago.

Still trying to figure out what's wrong with F111. Why is F111 looked down upon? From a manufacturers standpoint it's the simplest and least expensive to construct. From a jumpers standpoint you get unparalleled sub terminal slider up performance and it costs less – you don’t have to spend money on injuries or funerals anymore and you have more money to spend on traveling.

Vented ZP is acceptable for slider down because the p/c does not have a chance to oscillate enough to influence the canopy extraction and thus the opening direction. Vents on a ZP p/c clearly DO NOT eliminate sub terminal p/c oscillation - only reduces it 10 to 20% over non-vented. F111 DOES eliminate ALL p/c oscillation. In other words, non-vented and vented ZP !SUCKS! for sub terminal slider up! Make sense?

F111 being thought of as being too porous and therefore taking too long to inflate can be, and has been, proven fallacious by a simple spring-loaded test like TA has done. Give F111 a try...you will not be disappointed. Or stay on the vented p/c bandwagon for sub-terminal slider up until you hit a wall and break a foot, ankle, leg (and feel the effects FOR THE REST OF YOUR LIFE) or die. Good luck!

The Death Monger

while I am NOT convinced this style of pc will make a significant difference, Tom is correct. there is no harm in trying.

more importantly, kudo's to Marty. those pc's are works of art! keeping everything symmetrical and balanced must not be easy, or quick.

hehe.. why you pickn on me luv2fly? Yeah, I know, you're speaking all of us.

I personally have nothing against F-111. I also don't have any pilot chutes made from it. When I Purchased my first new rig, I bought a bunch of pilot chutes to go with it and still use them.

I bought the Toxic because it's very nice and the quality is supreme. The one pilot chute I still have that's not CR/Asylum is not symetrical (which on this PC is not a big deal). It's also not the size it's labled. The centerline was replaced by me because the original was made way too short by approximately 3 inches.

It's still fine for objects in the 0-1 second delay range, I'll continue to use on back to back loads.

As for F-111 being too porous, no, I don't believe that. It's definately not the case.

I've seen the drop tests on F-111 and ZP pilot chutes that were built the same and sure enough the F-111 was a lot more stable. We agree because it would be foolish not too. There's absolute evidence in captured on the videos.

If the PC's don't kill me, I'll show you video at the beginning of next month on how my 38s perform in the 5 second range.

from those who jump them, i've heard that the toxic is getting approx. 60-80 ft. faster than normal vented pc's.

Oh, that’s probably a slight exaggeration. It's roughly half to more than half the distance of a normal slider off deployment.

how long do you think it takes for a normal slider off opening?

Hi

I would like to know what gear configuration (container, canopy, PC size) and delay your observations are based on.

Would you say the faster extraction to linestretch is due to a quicker inflation or more drag, or both?

What size Toxic are you comparing to what size and type of normal PC?

I have video of a jump with a 46"AV PC, using my Blackjack 260 in a Paratech Odyssey FX.
I went stowed and did pretty much a drop-and-throw (it was from a lowish Tyrolean Traverse).

From the ground video you can clearly see my PC gets the container open before it has enough drag to lift the 260 out of the packtray (it has dynamic corners, so there is nothing holding the canopy in other than the flaps and pins/loops).

So for a higher extraction in that case the PC would not only have to inflate quicker, but have significantly more drag also.

thanks!
sam

Wow!

That's not at all my experience, based on around 100 jumps made on my 3 toxics over the past 2 months.

I think the Toxics do have higher drag (allowing you, incidentally, to use a smaller PC size for a given task, and thereby reduce your chance of hesitation). I'm not so convinced that they inflate faster. More consistently, perhaps, but not overall faster.

like I said, this what I've heard from people using them. They were using a 42" pc with ace and BJ 240's. I've got one on the way so guess I'll find out...

That's my exact set up.

To answer your question, roughly 120 to 150 feet slider off. (Mine seems consistant at the lower end of that estimate).

Shaving 60/80 feet from that distance isn't possible with a pilot chute.

What I do understand to be the case, slider up, subterminal(4-6 seconds) has shown a reduction in altitude necessary to have pressuration.

I don't know what the reduction is, 60/80 feet seems to be a stretch. I've only jumped it one time slider up subterminal so my experience on that will have to wait.

... Tom...

Will you show a few clips of the pilot chute in action please.

 
Since F111 virtually eliminates oscillation, why not just always use F111 for all subterminal or all jumps. Can the stability of F111 PCs be improved by venting (F111 stills spills air like a ZP, just not as much)?? Has anyone tested or used a vented F111 PC? Perhaps a Toxic built of F111?

Sounds like a good idea.

i do guess that if you want to make the same pull effect at your Vented F111 pc you´ll have to build it slightly bigger than a similar size zp pc.

And by nowerdays vented pc´s how big a problem is oscillation then?

 
Well, from what I hear people are still having dangerous oscillations with the vented ZP (even with proper symmetrical connection). So why not just use F111. Sure, it has a shorter lifespan, and so you may be buying a few more PCs in the long run, but I'd rather buy a few more PCs than a fat hospital bill. Why spend big bucks on a super sophisticated pie-slice ZP PC when you can get equal or better performance from a vented F111 (and have money left over to buy a spare)? Just wondering, not saying there's anything wrong with the current way, just exploring all the possibilities while trying to stamp out oscillations..

Im not saying your wrong,actualy people who wonders makes things better so keep it that way