Basejumper.com - archive

just curious. why would you want to tow a spongey, porous pilot chute behind you during the most important part of the sequence? why not all ZP
wondering opinions
aloha

I think it is much better to have 10000 microvents (like F111 naturally do have), as only one, if it comes to an orbiting PC.
second: the PC pouch should hold F111 better than ZP.

Downside: I guess after 80 jumps, i have to replace the F111 PC.

But i am only a rookie with little practically knowlegde....

cheers

i think that respect with regard to choosing F-111 or ZP, i prefer ZP, this improves the oscilations but retard 1 second in the opening, for this motive they do not use I believe in the pilot chutes of 48'' for example, since a rapid opening is needed and the oscillation is minor to this speed, but i have few base jumps

 

Can you please answer me, why a slightly bigger, new F111 PC should collapse quicker than ZP0 one?

I would also be interested, why in generally this days all PC are ZP (if i don't count the quicker aging)

Thanks

>> I would also be interested, why in generally this days all PC are ZP<<

The answer, like most answers, can be found in history (cue the dreamy music) . . .

Originally, when we started doing low jumps, all the PCs we used were way too big. The most popular one in the mid-80s was the Hank 52. This was originally a bomb retardant built by Hank Asciutto in Perris, CA. And it was neither ZP nor even F-111 which weren't invented yet. Besides being large it was heavy and built from bullet proof rip stop cloth like most round parachutes of the day. What weighed on jumpers minds in those days was PCs not inflating or getting stuck in the burble. The heft of the Hank-52 meant you could chuck it a mile and it always inflated. And the reason you see so many jumpers back then not folding their hand held PCs was these were so big and bulky they were impossible to fold and hold in one hand.

Over time we learned the burble wasn't that big of an issue on low speed jumps. And we also learned that hard chucking a heavy PC out to the side caused off heading openings. But this was before we knew those things, and even if we did, we would've probably still figured an off heading opening was preferable to no opening at all. And we didn't just start using big pilot chutes on a whim. While the first high speed jumps, like those made in the late 70s from El Cap, were done with standard skydiving gear that didn't translate very well to the low jumps of the mid-80s. And there were some incidents that weighed on us. Brad Smith had a low opening, almost on impact, from a 300-foot bridge and we attributed that to his PC being too small. Later when Steve Grysting went in at an early Bridge Day it was the same thing and also too short of a bridle. So really, before BASE rigs were available the very first pieces of BASE gear were big PCs and long bridles.

By 1986 I had a 48" PC built out of F-111. And by then everyone was switching to F-111. But they were still too big. It was then we realized how the drag of these big PCs affected the flight of our canopies. We called it towing a bowling ball around behind us. And a lot of newer jumpers were getting hurt as this configuration when flared too high would just shut down and dump them in.

So we started going smaller and smaller on PC size. And very gingerly at first because none of us wanted to find out how small was too small. Around this time, the early 90s, ZP fabric became available and we started using it at the drop zone in some of our skydiving canopies. Early ZP was nothing like it is now and at first we saw no BASE application for it at all. In fact there was even a counter-indication for its use when one well known BASE jumper did use an early ZP BASE pilot chute, but during a two way, the slippery fabric prematurely slid out of its pouch (built for a larger F-111 PC) and the resulting collision with the other jumper killed him. So now we knew. ZP was death in BASE jumping.

Meanwhile back on the DZ the new darling fabric of skydiving was ZP. As skydivers we started to realize its good qualities like zero porosity provided better flight characteristics and canopy longevity. And it opened the door to the smaller higher performance canopies of today. But down on the Flat Iron building as BASE jumpers we still wanted nothing to do with ZP. In fact we knew there were some definite advantages to good old F-111. Especially with canopies. We now had Velcro closed BASE rigs and the best set up was combining it with a very well broken in skydiving 7-cell like a Pegasus, Unit, or Cruislite. I say broke in because for slider down jumps these now high porosity canopies opened butter soft. And we thought that important so you didn't blow up the only canopy you had.

By this time we had comfortably come down BASE PC size wise to F-111 42" PCs. The first real BASE canopies like the FOX and the Mojo along with mesh sliders were also common now so this was a nice combo for almost anything other then the lowest go and throws.

But then a funny thing happened. The newest BASE jumpers coming over from the skydiving side of the house were completely unfamiliar with F-111. Maybe they knew their reserves were made from it, but that was about it. And folks like me who sold BASE gear spent a lot of time explaining what F-111 was and why it was better for BASE jumping to this new crop of jumpers.

So when the BASE gear manufacturers actually first started to think about using ZP in BASE canopies it was more from a marketing standpoint than anything else. I remember saying to Todd at Basic Research, "Hey, let's figure out a way to give them what they want."

But it was, at first, backwards to everything we knew. We weren't looking for speed or higher performance in our BASE canopies. In fact you wanted a big barge so when you screwed up and hit something, or just landed badly, you did it going as slow as possible. And then there was the issue of what happens when a jumper inadvertently takes a ZP BASE canopy that's slider down on a longer delay than planned. This happens due to tumbled launches, PC deployment problems, or, "Holy Fuck, I thought I was slider up." Would those mega-hard openings started causing unthinkable riser and harness failures?

And that's how we came to building only upper surface ZP BASE canopies. The lower surface being F-111 would somewhat negate blowing something up. And in fact when vents were first considered they weren't so much for pressurization but for relieving pressure as at that time people weren't doing the very low freefalls of today. Also in those days people were used to seven cell canopies and didn't think of end cell closures as an issue like some do today.

So now we had these "hybrid" BASE canopies but, at first, they still didn’t sell as well as the full F-111 ones. But the sport was still top heavy with old schoolers. Also at the time almost all BASE PCs we sold and what almost everyone was using are still made from F-111. And the few ZP pilots that were available seemed to have orbiting issues.

Then everything changed in just a few seconds when we had the Will Oxx incident . . .

Will was jumping a fairly low cliff over water. He was stowed and doing aerials. By this time, in the late 90s, almost everyone was always doing BASE with stowed pilot chutes. We'd figured out by that time, especially from Bridge Day, that new jumpers who had a high proclivity for blowing their launches were better off without a pilot chute in hand and all that bridle flapping around. And because they were skydivers they already knew how to deploy a PC from a pouch. So why make them do two new things. A zero airspeed launch while hand holding a pilot chute and bridle. It didn’t make sense. And all the experienced BASE jumpers took to going stowed easily as it was just so much cooler. And I helped it along when I came up with the saying, "If you can go, you can stow."

So Will Oxx launches, does his little flippy-do, and reaches back for his stowed F-111 pilot chute. And long past where he's expecting to get pulled upright nothing is happening. He pulled his body up into a ball trying to clear whatever hesitation he knew he was having and ran out of time as he crashed into the water just as his canopy began coming off his back. If it hadn't been for the water Will Oxx would be residing on the BASE Fatality List.

We looked at the video a hundred times. And we realized despite a good deployment his F-111 pilot chute, for whatever reason, just didn't inflate when it should have. And like they almost always do. So that was when we started taking another look at ZP pilot chutes. And not for reasons of pulling power or longevity. It was simply because they were not as likely to stay wadded up. ZP just naturally wants to expand.

We finally fixed the ZP PC orbiting issues by building them as symmetrically as possible, teaching jumpers they have to be attached to bridles with a very straight angled knot, and eventually giving them vents so they orbit around that column of air. And so little you can’t see it. The fact that ZP was easier to market to new jumpers made the whole thing a win win for everyone.

So that's why most of the BASE pilot chutes sold today are ZP . . .

NickD
BASE 194

What is the consensus about the average F-111 PC longevity ? Then, would you use an old 38 instead of a new 36 for recycling it?



I guess repacking the PC just before _every_ jump, particularly if made of F-111, is definately worth it... Besides, just shaking the ripstop while keeping the bridle and mesh packed is generally enough and only takes 45 secs.

why not wait to pack the pc until you're gearing up?

I see little reason to pack my pc when I pack my canopy. it lays fine in my gear bag, an unpacked pc does NOT stretch out the pocket, and it tells me which pc is attached.

It's even better, your right...
To answer your question, probably because I'm used to do it this way..besides all my PC's have a different color and my pocket is streched to it's maximum anyway

I've seen a F111 PC that's been stowed for over a year taken out of the pocket. You could toss that sucker across the room without it really changing shape. That's when I started stowing mine just prior to the jump/climb/drive.

When buying my PCs I asked around for a while and found really it came down to risking a minor chance of either hesitation (F111) or off-heading (ZP). Assuming you did all the other things right and weren't doing something silly.