PC hesitation discussion

[guest]

I've had similar experiences. I tend to agree with Bryan that the prime cause of PC hesitation is stowing. I've noticed that I get a PC hesitation rate of around 1 in 10 doing "stow and go" deployments (i.e. a stowed deployment with zero delay). I had a conversation with a BASE gear manufacturer after one of these experiences off a 300' cliff in Moab, and he described it as "random stowed hesitation." Basically, he meant that sometimes stowed PC's just hesitate.

My advice: if you can't afford to have a PC hesitation, go hand held.

I would like to see (or do) some research on hesitation. I have ruled out the "bridle-over" malfunction by video evidence on more than half of these stowed hesitations. I'm sure that it can happen (I've seen the video), but I don't think it is the primary culprit. I just have too many videos of my PC at full bridle extension, with the mesh fully extended, flapping away (not inflating). When I examine it frame by frame, it looks like it should be inflating (airflow straight up into the mesh, bridle and mesh fully extended) but it just isn't.

The only cause I have been able to identify (by statistical inference) is the length of time the PC remains packed and stowed prior to the jump. I have a far higher rate of hesitation on a PC that was stowed at least 12 hours prior to the jump than on PC's stowed at the exit point. Call me superstitious, but I've taken to stowing my PC as close to the exit as possible for the way low (300' or less--yes, I know that's too low to go stowed) stowed jumps.

Anyone else have any possible causes?

--Tom Aiello
tbaiello@ucdavis.edu

[guest]

Hi guys,

I'm just looking for a bit of a discussion about PCs. 2 nights ago I had a pretty serious PC hesitation with a ZP PC. We were jumping a 380 ft object where you have to do a 1 - 1.5 sec delay to make the good landing area. I did a 1 sec delay with a 42" ZP stowed and proceeded to tow it behind me for about 200 ft finally opening with just enough time to turn and make the crap alternate landing area. I had a similar hesi at the tree in Chamonix although not for so long and I'm now of the opinion that F111 is the way to go. I believe that the ZP may have hit the airflow side on and wrapped around causing inflation problems.

Anybody else had any similar experiences or alternative views on this issue?

Cheers,

Craig

[Yuri]

Yo !

I believe that F111 will give you a higher chance of PC hesitation at low speed and altitude, especially when going stowed (ZP wants to expand while F111 wants to stay folded). However the difference between F111 and ZP is so minimal that i haven't seen any hard proof to support either opinion. I guess there are other factors, more important than PC material...

bsbd!

Yuri.

[bps]

Hello Craig -

This might be a short response...I'm an instructor/teacher and I'm in-between periods right now.

I'm also curious about PC hesitations and have studied them through my my own experiences as well as others.

I don't know if I agree with F-111 being any better than ZP when it comes to "collapsing on the side". If there was enough side-influence to collapse in the side of a PC, I don't think that low-porosity would make any difference. Maybe in small scientific measurements -- but not in the big picture.

I do believe in two things that can and will cause PC hesitations:

1) Bridle-over-the-top. (a line-over of sorts) I have seen direct proof of this on video. Last year, I shot video of the owner/inventor of the BASE Board and noted to myself that he had a decent little PC hesitation. Afterwards, we slowed it down frame-by-frame and you could clearly see the bridle over the top of the PC and as the PC inflated, it hung on for a split-second and then rolled off to the side. It was difficult to see with the naked-eye until you saw it on the video.

A bridle over the PC is one reason I'm a big fan of no outside handles on pilot chutes for jumps with low to medium speed deployments. If you have an outside handle and it hangs-up when your low...

I believe that a bridle over the PC is less likely to occur when you go hand-held. To demonstrate this to yourself, pack-up your PC on the ground for hand-held (s-folds). Now throw it out to the side and notice how the pilot-chute's deployment is well-staged -- it springs out like an accordian.

Now pack-up a PC with the mushroom-method to go stowed. As long as the stowed bridle is controlled by your hand as you extraxt the pilot chute, its deployment is well-staged. But if the PC pack job is sloppy, or if you extract in a hurry and just dump it out into the airstream, it is quite possible for a lump of bridle to suspend itself above the pilot-chute before it has a chance to inflate. The PC inflates into the bridle and presto, you have a bridle over the PC. This problem is more prominent during low-speed deployments and is something to consider if your jumping a low object.

2) With large-bore mesh, it is possible for the mesh to stick together (or on something else) when going stowed. Yes, it is unlikely, but during a low-speed deployment, it could take a slight increase in airspeed before the mesh can release, allowing the PC to inflate. Once again, hard to see with the human eye in real-time, but something that is definitely noticeable to the jumper during a low or ultra-low freefall.

There are many other factors involved, but these are two things that come to mind. I've had 3 noticeable PC hesitations in just over 200 jumps, and have witnessed about half a dozen more on other jumpers. Through this and slow-motion analysis on video, I've come to the above conclusions.

How about the rest of you out there - any other thoughts or ideas?

C-ya!

Bryan

[guest]

One possibility that comes to mind: bridle
catching the lower corner of your rig. If you
went hand held, did you attach your bridle to
a velcro piece on the bottom part of your rig
to prevent this?

[guest]

I allways do this when going hand held but on this occasion I went stowed and tucked the bridle in to prevent accidentally pulling the bridle with the PC.

Craig