I've been using a 42", vented, ZP pilot chute for freefalls in the 270-290' range, some stowed, some hand held; what are the chances that I could get a PC hesitation due to the venting?
I know it works; but would I be better served with a non-vented PC in order to get a faster inflation and higher snatch force from that altitude?
Is PC oscillation even an issue at that height?
With this scenario, what would the difference be between unvented ZP and F-111?
At that height, and my experience level i'd be using a 46 or 48" PC. Where are the experienced guys input on this?
"What kind of man would live a life without daring?
Is life so sweet that we should criticize men that seek adventure?
Is there a better way to die?"
Charles Lindberg
August 26th, 1938
Why the hell would you go stowed from that height? Does it make you more hardcore? You can take a longer delay going HH, I've never understood newbies and their thinking on this stowed business sub 300 ft. In my opinion Davo is right, you should be using a 46-48 from that height. Some will disagree and say they have used 42's for 100s of jumps from that height and lower but why not use a bigger PC. Your delays cant be more than 1.5-2 maybe.
vented compared to non-vented makes no difference IMO. don't think the vents will be more likely to cause a hesi either.
personally i don't go stowed below 300 very often, but in some cases the exit point warrants it for me to do so. i do however jump 42s in that height range quite a bit (with 280' tarps) and they work great. i tend to pick a PC for the desired delay, not the height.
the only thing that i think is silly about going stowed low, is when, for instance, people are jumping something like Tombstone, and their hand is on the PC and pulling before or as they step off. i see this a lot, and that is seriously retarded.
anyway, it really doesn't matter... do what you want.
If your planned delay is 2 sec......I use a 42. Who cares how tall it is! My 48 scares me anyway, seems just TOO big.
I agree about stowed sub 300, scary stuff. good for you guys! I dont really see the point unless the exit point warrants it, or you are working your way to do gainers!
Realistically, what is the actual PC inflation difference between going hand held vs. going stowed? If I launch and go beyond a half second pause before pitching, I don't think the pilot chute cares whether it was launched from my hand or flicked out of my pouch? There isn't going to be any appreciable difference between the two.
Now, I can see hand held being useful in uber low free falls where you want to, essentially, pitch at the same moment you launch, (but again, realistically, what is the difference if you throw immediately from your hand or like Blitzkreig said, leave with your hand on your BOC?) The only benefit I can see in that situation is that hand held you can pitch upward towards bridle stretch and get an extra couple of feet of inflation.
As far as why; while the exit points do not necessarily dictate going stowed, I feel that stowed is a much cleaner and much simpler exit. We just had a situation at the top where, while going hand held, a jumper popped his lower pin climbing over the railing to the platform. It wasn't a difficult climb over by any means, it's just Shit Happens. Hand held is just an additional set of parameters to worry about.
The original question of vented vs. unvented came to mind after randomly rereading an article by TA saying that vented pilot chutes inflate slower than unvented pilot chutes. It makes sense, due to the fact that you don't have a big hole in the apex of your PC to let air through, but I just hadn't really thought of it that way and how it might relate to low freefalls.
Oh, and no, it doesn't make me more hardcore, it makes me more comfortable.
Huck, I guess I don't see your rationale for saying that you can take a longer delay when going hand held? Why is that? The longer the delay, the more rationale there is for stowed.
Just my thoughts
RE: handheld versus stowed
Yes, some exit points require both hands to access.
However, some 'Mountain Dew' types prefer to make
PC location decisions based on some 'Rad' factor
I personally prefer handheld for lower jumps and
agree that if you are humming it (short delay/low)
object then handheld allows you to go lower safer.
If you hum it low stowed and fumble just a touch
then things could get dicey really quick, not good.
RE: venting
A vented PC's slower inflation is a trade off for less
PC oscillation and consequently a lower chance of
having an off heading.
I think we all agree that opening 20 feet lower but
on heading is better than open higher with a 180.
I have video of a guy going stowed from 300' with a vented 42 and it is probably the closest I've been to cleaning blood and guts off me and those around me. If you think it can't hesitate think again. Both going stowed and being vented played into the delay. 4 secs from exit to canopy overhead... You do the math...
S K E T C H Y
Acceleration due to gravity on earth without any air resistance equals 9.8m/s/s
or 32ft/s/s. If there is higher humidity, the air will be more dense, resulting in
more friction which reduces the rate of acceleration.
For simplicity, assume that jumper is at sea level with low relative humidity.
The idiot's guide to physics of acceleration and speed uses 10m/s to calculate
speed and distance over time, since 9.8 is pretty close to 10:
10+20+30+40 = ~100m after 4 seconds of freefall
1 meter = 3.28 feet
4 seconds from the Perrine is dicey but
4 seconds from a 300 foot freestander
Of course even an un-inflated PC would have
slowed his or her descent a marginal amount.
Good work. So like I told the jumper wind resistance saved his ass!
I'm not going to disagree with this statement; but, it holds just as true other way as well...Originally Posted by Greenmachine
...then stowed allows you to go lower safer.
If you hum it low hand held and fumble just a touch
then things could get dicey really quick, not good.
You've got every opportunity to botch a hand held, just like a stowed.
- Ever seen anybody stow their bridle incorrectly?
- Ever seen anybody wrap their bridle around their hand?
- Ever seen anybody throw their PC into their burble?
- Ever had the tailwind blow your mushroom around your hand right on exit?
Now, I'm not trying to prove that one way is better than the other, they've both got their pros and cons. It's like most other things in BASE, what works best for you taking into account as many variables as possible; height/delay/landing area/comfort level/mind fuck/etc...
i'm not saying the hesi wasn't scary... but are you actually saying 4 seconds from exit to canopy? that is pretty normal sounding to me for a go and throw even. count the seconds on this one from 265'...
BASE Jumping Videos: ~265ft FreeFall
just saying...
1. Sure, but you've got all the time in the world to double check it at most exit points.
2. Yea, but it's preventable with proper technique.
3. No, not that there's much burble happening on a sub-300' jump anyways.
4. Only if you use the open mushroom technique. Why not just S-fold the whole thing?
If the idea is to deliver the PC to bridle stretch as quickly as possible while minimizing the chances of interaction between the bridle and the PC itself AND minimizing the chances of oscillation, then going handheld is going to provide a more consistent result, especially at lower airspeeds on shorter delays.
Most people who take short stowed delays have a tendency to pitch their PC with a flick of the wrist, sending their PC tumbling through the bridle on its way to bridlestretch out to the side of the jumper. Sure the chances of the bridle hitching the PC are minimal (especially without an external handle), but this has caused more than one fatality.
Egad, a BASE life defiles a bad age.
The video Tony is talking about was from YL in Moab. ~300'. Skilled jumper goes stowed, takes a standard 300' delay at 3500' MSL, and has a hesitation. As jumpers, we know what "it opened at the last possible second" means, and it opened at the last possible second. It opened just in time to surge him into the tree next to the landing area turnout.
If you want to go stowed, go stowed. I've noticed the same thing with newer jumpers, thinking that once they got their Perrine progression within three jumps, (PCA, HH, stowed), they never look back. Got to look like a badass and not a newb, so huck it stowed.
And think of these things as planned time of delay. Personally, unless I'm doing aerials, or the exit won't let me prep up, I go handheld under 1.5 seconds, most of the time. In my opinion, you lose a little by immediately cocking back to immediately pitch at low airspeeds. I also think, more pronounced at lower airspeeds, that when you throw a stowed PC out, it inflates off to the right, then swings back, instead of presenting a PC along the centerline, handheld. Might be psychological, but if you're learning low freefalls stowed, the first couple times you're going to throw that thing as far and harder than ideal. And, generally, I think the incidence of hesitations is greater when going stowed instead of handheld.
And my understanding was that venting is a solution to pilot chute oscillation at higher airspeeds, and doesn't necessarily reduce the chances of hesitations. Don't know if that's correct or not. Either way, the pilot chute, for being as simple and relatively inexpensive to the whole system, is probably the most important thing you have with you on the jump.
Its just BASE jumping, do it your style. Have fun.
Last edited by base935; March 5th, 2010 at 02:28 PM. Reason: Thought of another thing to solve all of BASE jumers problems.
Posting Permissions
Reply With Quote
Bookmarks