I have a fox 285 (non vtec) and was wondering what can be done to slow the opening shock on slider down jumps. Currently, I expose and stretch/open the center cell around the top of the pack job inside the container (deep brakes).
Does anyone have experience rolling and tucking the nose, like a slider up terminal speed pack job, on a slider down pack? Any effect on heading?
Martian Bob
Hi Bob:
My experience has been that opening the center cell greatly promotes on-heading performance. I currently open the center cell (wrapping it all the way around the entire pack job) on both slider up and slider down pack jobs (even at terminal).
I found that I was more willing (especially on slider down jumps where you open close to the object) to accept a hard opening than I was willing to accept an offheading and potential object strike.
Note that I do roll the outer six cells on both slider up and down jumps. The idea of this is to promote inflation only through the center cell, and inflate the other cells initially through the crossporting. I'm not sure of the effect of this practice. I've heard speculation that it gives slower (softer) openings, but I have used it successfully on free fall deployments as low as 200', and have not noticed any hesitation in inflation.
Perhaps it might be better to consider taking less delay to soften the openings, rather than compromising your heading rate. Alternatively (if heading is unimportant--say on a forgiving span), you might just want to put a slider on, and get a truly cushy opening.
--Tom Aiello
tbaiello@ucdavis.edu
I've had softer openings not using a locking
stow, which should only be done in combination
with a tailgate and a tailpocket that won't dump
prematurely. Deep brakes also assist in slowing
the opening slightly. I've not really had
any results doing things to the nose.
Regarding slider up, rolling the outer three
cells on each side a couple times, slight exposure
of the center cell, folding the stabilizers, and
rubber banding the brake lines to the trailing
edge of the slider seems to give consisently
non-hard on-heading openings.
I agree with Tom.
Depending upon the object and the amount of risk during an off heading (eg. low cliff vs. bridge), I wrap the center cell more or less around the pack tray. The more you wrap, the harder the opening in my experience. But you also have more assurance that the center cell will aid in an on-heading opening.
But the less you wrap, the softer the opening. This is, of coarse very dependant on your delay. A deep delay=hard opening. Can't really change what a deep 4+ second feels like slider down.
Also, try PC sizing. A 46" slider down on a 3+ second delay will also add to how hard the opening is. You may find that a 38" fits you delays, or maybe a 40"-42". you really need to assess the jumps to determine that.
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Mick Knutson :D
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Hi Martian Bob,
I too had issues concerning the slowing down of slider down/off pack jobs. After toying with my packing a bit, I came up with a pack job that should give you long snivels, and never open hard. OK, so I didn't come up with this totally on my own, but the guy I got this pack from, won't remember the pack anyway. Hell, I was with him once when he actually forgot where he was! (How do you not know you're in an international airport?)
So this guy....he calls the pack "The Corn Dog". From what I recall, the pack is a loose combination of the psycho pack and vodka. (possibly other pain killers, but that is just speculation at this point.) Hey man, I was there, and let me tell you, this pack could never open hard. For curiosity sake, we did a simulated deployment, and this pack sniveled lllllong. And this was just in the living room! I can only imagine how soft it would open from 390'. I bet if you flicked, closed your eyes and deployed, it would almost feel like nothing was happening. Now that's what the boys are looking for!
So in summary, there are a few basic rules to follow in packing The Corn Dog; Always start The Corn Dog late (like 3-4 AM), use at least 4-6 hours before the pack to "prepare" for the actual pack, cock your pilot chute (you should always use a collapsable pilot chute with The Corn Dog, it creates less drag after opening, allowing your Fox 285 to out surf anyone dragging a 42" anchor behind them), and of course, don't you go worrying none about them there line twists, it's probably just an illusion created by them new fangled digital cameras. That digital seems to distort images, due to the Coriolis Effect, and make The Corn Dog deployment appear as if it's nothing but a ball of sh1t, when in reality (analog), it's just a standard Corn Dog being flown by a highly skilled "BASE GOD". Hope this helps!
Happy Birthday Bob, and of course, Mince Division!
(These other posts seem like decent ideas, but are they really pushing the envelope? I think not. Don't be a follower!)
Thanks for the tips,
The object in question is about 460 feet with a large soft landing area, no real threat of an object strike unless you compound several bad decisions. I've been using a 42" pilot, tail gate, 0.8 loading, velcro rig, with about a 2 sec delay. I was only considering increasing the delay to about 3 seconds.
I'll have to do some tinkering on a higher free standing object.
thanks again all
cheers
Bob
Hmmmm. Sounds familiar. Does the crackling of power lines figure prominently at the exit point?
If so, I'd recommend not using a slider on it. The legs on that thing come out enough that a weak launch combined with a slider could yield object strike during deployment.
--Tom Aiello
tbaiello@ucdavis.edu
Better to cock your pilot chute that shoot your pilots cock!
Also, how many wraps, on what size rubber band are you using on the tail-gate?
I found that the more wraps on the tailgate, the harder the opening. I actually took a 2 second with 4 wrapps on a small rubber band once and got the shit knocked out of me!
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Thank You
Mick Knutson :D
[link:www.blincmagazine.com|BLiNC Magazine]
"Everything you ever wanted to know about BASE Jumping, but didn't know who to ask."
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[font size="1" color="#FF0000"]LAST EDITED ON May-02-01 AT 07:25 PM (PST)[/font][p] >Deep brakes also assist in slowing the opening slightly.
Chris,
Can you elaborate more on this point? I have often wondered what effect the brake settings had on opening speed. The rumor I had heard (one of those "I once knew a guy whose uncle said..." ) was that deeper brakes led to faster openings.
Does anyone have any information on why deeper brakes make the opening slower? Would the fastest possible opening be an unbraked canopy? Or is there an optimum brake setting for fast openings?
I've had my eye on a low site for a while. It is a span with a totally open landing area, so off headings and forward speed on opening are non-issues. What kind of brake settings do you think would yield the fastest opening?
Does anyone else have any thoughts? (DW, I know you have done more low jumps than the rest of us put together--what's your view?)
--Tom Aiello
tbaiello@ucdavis.edu
Hi Tom,
the openings on slider down are primarily determined by bottom skin inflation and not by cell pressurization. Once the bottom skin inflation has pushed the canopy apart, the canopy will coast forward determined by the trim of the canopy and by the brake settings. Air will pass over the top skin and pull it up while some air is starting the enter the cells. This contributes somewhat to the opening shock. With deep brake settings, the canopy will not coast forward much and the cell pressurization will be slower after the bottom skin is spread. With shallow settings, the canopy will coast forward a great deal and allow for the cells to pressurize much more rapidly.
Regarding my original post, not using a locking
stow seems to reduce the distance it takes me to
get open, but the opening shock is milder since
the opening is a more continuous deceleration.
For really low jumps though, I think a careful
factory pack is quicker. It will open (that is
unfold) quicker since it has less folds than a
pro-pack. The pro-pack has a fold to make it
narrow enough to fit in the container, whereas the factory pack does not. However, you could use a propack with a narrowing fold toward the nose and not the tail. That would cause the it to unfold during linestretch.
bsbd, Chris
>Does anyone else have any thoughts?
>(DW, I know you have done more low
>jumps than the rest of us put
>together--what's your view?)
Do you want the short response (this is how I would configure my gear when say punching a double gainer with stowed deployment from 180') or the long response (with justification and examples which back up every statement made, which will vary depending the different types of equipment to be used...blah blah blah).
I'm kind of busy at work....
Or do you just want to wait 8 days and get the practical lesson in low freefall rather than just the theory?
You know me. I want the long response and the practical lesson.
But if you're too busy I'll just corner you next weekend for a combined lesson.
Thanks.
--Tom Aiello
tbaiello@ucdavis.edu
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