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I like someone to explain me why can someone choose to have a non-zero porosity pilot chute to do base. I understand the meaning of a slider for some high jumps in order to slow down the opening of a canopy, but the pilot only slow down the canopy getting out of rig. So that seems stupid to me, if i want to slow down the first fase of opening i just release the pilot a sec. later.
This is comon-sense for me, but i know its wrong cause there are ppl using non-zero porosity pilots in base.
So what i like to know is the advantage of doing it, and if its not the same as using a zero. one and retarding 1sec the release of it.

Thanks ppl

how does that work???you mean if you want to be closer to the ground right

I think most people will buy zp pc´s if they buy new today,but the old F-111 still works,thats why people still use them...Your F-111 BASE canopy also still works,and not many is buying zp topskin as i have heard off...

I cant tell why people use them,i myself got rid of all F-111 pc´s and now noly has zp pc´s(all vented besides one 46´ which i just got)

There are many good reasons for using an F-111 (non ZP) pilot chute for BASE.

The primary reason is pilot chute orbiting (or oscillation). All pilot chutes will pass some amount of air through (otherwise, they'd be stuck in mid-air, and not descending). A ZP pilot chute will pass this air by spilling it sideways, from the edge of the skirt. This means that the ZP PC will develop some sideways drive, possibly resulting in an orbiting pilot chute. PC orbiting is a leading cause of off heading openings.

In short: ZP PC => Greater Chance for Orbiting => More Likelihood of Off-Heading Openings.

An F-111 PC, by comparison, spills the air evenly through the fabric of the pilot chute. This tends to dampen the oscillation (even if you induce oscillation by a vigorous sideways throw).

In short: F-111 PC => Less Chance of Orbiting => Generally Better Opening Heading.

The trade off is that ZP PC's tend to inflate faster/hesitate less. In general, if I am doing a lowish jump (sub 400') I'll go with ZP, usually vented. I begin to consider removing the vent when I drop below 200' exit altitude on a freefall deployment. For slider up jumps, unless I am planning on a low pull (i.e. more time in free fall than under canopy) I almost always opt for an F-111 PC. Another disadvantage of F-111 is that it will wear out faster than ZP.

Obviously, this is an over simplification. There are some other options (such as vented ZP pilot chutes) that combine some of the better facets of each option. And not all vented PC's are equal, either, as the vent size, shape and location can vary depending on the manufacturer.

I've split the two sub-discussion (PC wear and PC venting) off into their own threads, if anyone is looking for them.

I pretty much followed experienced jumpers' advice when buying my first set of PCs. Now that I am jumping I've started to form my own preferences, eg I prefer a F-111 42" PC because it feels more secure in the pouch when going stowed.

On a slightly related note (not trying to cause another thread split or anything ) : I'd be interested in peoples preferences for how big a PC you'd go stowed with. Personally I won't go bigger than 42", but was wondering if there are any experienced jumpers out there who go stowed with anything bigger? (if so, why not go handheld?)

One argument I've heard is that if there is a tricky climbout to the exit point requiring both hands it might be better to go stowed (on an object requiring 45" or 46" PC). Any other reasons to go stowed with a larger (than 42") PC?

Will

I hate to admit this, but...

I have had two big reasons for going stowed at low altitudes at various points in my sordid past.

1) At one point I was uncurrent with hand held, and kept getting consistent 90's left with a hand held PC. This was because I would pitch with one side of my body and dip that shoulder during the opening sequence. I sorted it out with video and started doing a symmetric "fake pitch" with the other hand. But for a while there, around 200-300 jumps, I really was getting better heading stowed, and I'd go stowed when heading was important.

2) I used to go stowed from low altitude for the wow factor, to impress skydivers, to get chicks, etc. I don't recommend this, but I do understand it.

I don't recommend it, and I don't do it much anymore, but my 48" has been inside my BOC plenty of times.

Doesn't this cause undue stretching of your BOC spandex (in particular the mouth of the BOC)? Would you stow it just before gearing up for a jump? (ie not when you packed)

BTW what is your average number of jumps before you have the BOC spandex changed?

Will

It hasn't been too bad, actually. I haven't done any careful studies, but I haven't really noticed a problem.


Yes. Anytime I did a low stowed jump (below about 300' or so), I'd stow the PC as close to the exit as possible. I started doing this after a PC hesitation from 300', on a PC packed the night before, in which the most knowledgable jumper on site declared the problem to be "random stowed hesitation." I think that a PC packed for less time will tend to inflate quicker and hesitate less.


Gosh, I dunno. I've only ever replaced BOC spandex on one BASE rig. It probably had about 300 jumps on it at the time.

OK, thanks. On low objects that you've jumped both handheld and stowed - could you tell the difference in terms of hangtime? I appreciate that handheld the PC would inflate sooner, but given the snatch-force required to open the container did going stowed make any real difference?

Also, what was the largest PC you've used for a slider up jump and what was the delay?

Cheers for the feedback.

Will

Definitely.


42". 4 second delay. I've probably also done a 42, slider up at shorter delays (3 or so) when trying to time a multi way, or just because I'm soft and was doing many jumps in a short time and wanted softer openings.

But the largest PC for a slider up jump where I was focusing on the mechanics of that particular jump was a 42" PC with a large mesh slider taking a four second delay. It was pure silliness.