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worldsocold

wind down the guywire???What Do You Do???

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Do you all also climb down in zero wind??

If you jump with wind in the middle of the sector, a percentage of the wind is pushing you away from the wire. If you open facing the wire your approach speed towards the wire equals canopy speed minus the push off factor of the wind speed. All the wind is also pushing you away from the tower. Obviously idea conditions!

If you jump with the wind directly down the wire, 100% of the wind is pushing you along the wire. The wind not pushing you away from it, but it is also not pushing you on to it. If you open facing the wire your approach speed equals your canopy speed, but if you open facing the tower all the wind is pushing you away from the tower, parallel to (not on to, or off) the wire.

If you jump in Zero wind there is obviously no wind pushing you onto or away from the wire. If you open facing the wire your approach speed towards the wire equals your canopy speed and if you open facing the tower, your approach speed towards the tower equals your canopy speed.

Obviously all winds in the above are the wind at opening altitude and this can be very different from the wind at exit or landing due to wind sheer.

Wind can obviously increase the chance of an off heading, but if you jump with the wind directly down the left wire and open with a 90L you have no more chance of hitting the wire than you do if you jump in zero wind and have a 90L. But that said you have more chance of having said 90L

Greeny

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if you jump with the wind directly down the left wire and open with a 90L you have no more chance of hitting the wire than you do if you jump in zero wind and have a 90L.


most often i would say that the canopy opens towards the wind,which in wind down the wire will result facing the corner of a wire and the tower,as you have twind pushing you away from that corner it aint as bad as if you get the 90L flying down/into the wire,as you´ll have more speed from wind,you´ll have less time to correct before you fly into the wire.

0 wind is more gambel than wind down the wire(in some degree) i agree,i rather expect an offheadding into or or away from the wind than getting an 165 off in 0 winds..

Stay safe
Stefan Faber

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If you're taking a 6 second delay from 1000ft (not including any wind shear), how much wind could you really have affecting your opening? After 5-6 seconds, your body should be moving with the wind horizontally... so where is this 'wind' that you are worried about causing offheadings?

(i know that this only applies in constant winds with no wind shear... otherwise any number of scenarios can come into play (from personal experience))

Winds obviously can have a huge influence on opening headings on lower objects, but after 5-6 seconds of freefall you really shouldn't have any problems (unless the winds are strong, or they are doing funky things... which you should be observing on the climb up)
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Cleveland Skydiving
"Hey, these cookies don't taste anything like girl scouts..."

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Greeny is correct.

No winds are more dangerous than winds down the wire. Do a simple vector diagram analysis of the problem.
Looks like a death sandwich without the bread - Steve Deadman Morrell, BASE 174

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Greeny is correct.

No winds are more dangerous than winds down the wire. Do a simple vector diagram analysis of the problem.



agreed.

for lazy/stupid people:

wind down the wire makes the 120 degree 'optimal' opening range of the sectors moot.

all you have to worry about is the wires that the wind is blowing down.

basicaly, it turns a A into a A with wires at 180' abgles, not 120'

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Greeny is correct.

No winds are more dangerous than winds down the wire. Do a simple vector diagram analysis of the problem.



How so? With winds down the wire, the canopy is being pushed down the wire, where the wires are converging and distance between the wires is decreasing. In no wind, this added factor is not there. I've personally watched 3 seperate occasions where people have flown between guy wires on a large tower, with 150' between each wire at the tower connection point. I do not have an accurate guess of how far away from the tower they were.

This is not a simple problem. Which is safer will depend on whether you consider the wire or the tower more of a threat. Personally, I'd rather hit the tower than the wire. I'm also much more confident in my ability to avoid a giant obvious tower at night than a thin, hard to see guy wire (with half or less moon).

If jumping slider up and taking a 5-6 second delay, you have absolutely no excuse to hit the tower in no wind. If jumping slider down and taking around a 3, which I have done many times, I feel the same way.

A guy wire is not a solid wall.
A waddling elephant seal is the cutest thing in the entire world.
-TJ

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If you treat them as a solid wall, you will not get an accurate assessment of risk exposure for each available option given specific conditions.

^yay wordy sentences
A waddling elephant seal is the cutest thing in the entire world.
-TJ

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Summary:

With "enough" winds between the wires, a guyed tower is a relatively safe object. With a simple diagram, you would understand that the angle of the wind is constant, and the distance from the wires is increasing with every moment. You get the thrust from your jump away from the tower, wind drift in freefall away, wind drift once the canopy opens, and even some subterminal track if its tall enough. With a 180, you're in the same situation as when you get a bad spot at the dz, and no matter how hard you try, pointing back at the lz, you can't make it.

Without winds, you are jumping not only something as "unsafe" as a building or underhung cliff (things hanging off the A), but you are jumping a notch. With the B or E, you have 180deg of "freedom", 90 each direction. With the windless A, anything more than a 60deg offheading, and you will be screwed without immediate input. And you're right, the wires aren't walls. They're worse. What is that going to do when you hit it with your neck or body, halfway up your lines in flight, or tear your canopy in half on guywire.

You aren't always guaranteed a jump when you show up at your local slider down cliff, sometimes you will have to walk away from your building after staying up all night, and might even get winded off the Prine. It sucks, but you might have to climb down from a tower, asking here what you already know is the right decision won't make it any safer.

BTW, if the winds are between the wires, but blowing harder than you want, and are still going to go, consider some things. Strong tailwinds are going to slow your opening, air isn't getting forced into the open nose cell. You might want to practice your handheld action, you're increasing the chances of having the bridle wrapping around arms or body. Head high will also be better than head low. And if you still have to go, you also might want to consider climbing a little higher and getting a little more delay time. If the winds are strong, and not perfectly between, consider a little push off into the wind, and keep in your mind that when the canopy opens "perfect", there is a better direction to turn back into the wind for landing. That is if you still insist on going.

That should be enough loose generalizations for one post, have a great jump.

Choose your own level of danger.
Gravity Research Institute

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read Yuri Kouznetsov's (outrager) article on the subject. it changed the way i thought about the risk assessment on sites, particularly towers. zero wind will always be more dangerous than moderate wind down the wire.
Looks like a death sandwich without the bread - Steve Deadman Morrell, BASE 174

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Strong tailwinds are going to slow your opening, air isn't getting forced into the open nose cell.



i disagree there, IMHO, the canopy will open the same assuming the person is in freefall. the only thing wind changes is relative body postion.
(thus why a xwind causes opening to face into the wind usualy, its just like if your right shoulder low, you usualy get a slight right opening, the same as a right wind)

PS- remember, everything causes lineovers. everything. especialy normal , stable, belly down jumps.

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some of my comments have gotten some responses via PMs. OK, firstly, make up your own minds on what you think is correct. Your the one who will have live with it. These forums are great because they have so many different opposing *good* ideas. Here's a thread from BASE 311 regarding Yuri's antenna comments... However, I disagree with 311's heading alteration with winds down the wire. I prefer to get a good canopy and deal with it then. Altering your exit heading is leading to off heading opening disasters. I have a friend (BASE 175, he was Yuri's mentor) who used to actually alter his exit heading parallel to the downwind wire because he hated the hard off headings and partial line twist potential because of the wind sock inflation issue. This is only for the advanced jumper though.

Here's 311's comments from 2003 here on dz.com:

it's been my experience that there is almost always some shift as one climbs. I always assess what the winds are doing at opening altitude and keep that in mind as I'm climbing. generally I haven't experienced a situation where the winds do a full 180, but also I generally only go to about 500feet and slider down when climbing.

When there's an elevator, it pays to stop at opening alti and get out and see what's happening. you can't tell what the winds are doing when you're inside the elevator. If the elevator is one that is so sensitive and fickle that you're afraid to stop it once you've got it going, then you probably have someone riding on top of it anyway and that person can check the winds. I'm wondering if this might not be what happened to the fellas mentioned in the darwin candidate II post where they exited and opened on the upwind side... they may have actually been exiting with the winds on their backs or down the wire - only to have it become a headwind at opening. I don't know for sure, but without stopping and getting out of the elevator at opening alti, there's not much way they could have known (unless they went against the flight pattern that prior loads had used - which would have been cause for alarm for me) what the winds were doing there.

Yes, it's typical for it to be nil on the ground and downright breezy at alti. I've jumped in winds of perhaps 30-40 (maybe 50) mph on my back at exit... perhaps 15-20 at opening and zero on the ground. I'm more concerning when there is no wind at all at opening alti. On towers it is good to have a tailwind splitting the sector in which you'r'e jumping; that helps you when there are off-headings. If the wind is down the wire it has been theorized that even that is better than no wind at all (see outrager's post on blinc mention in another thread), though I'm much more cautious of winds down the wire... usually opting out or altering my exit heading - exiting so I'm facing more toward the wire on the opposite side away from the downwind wire - putting the opening more crosswind hoping for an off-heading away from the downwind wire (most times it works). YMMV

bsbd,
Gardner
Looks like a death sandwich without the bread - Steve Deadman Morrell, BASE 174

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i disagree there, IMHO, the canopy will open the same assuming the person is in freefall. the only thing wind changes is relative body postion.
(thus why a xwind causes opening to face into the wind usualy, its just like if your right shoulder low, you usualy get a slight right opening, the same as a right wind)

PS- remember, everything causes lineovers. everything. especialy normal , stable, belly down jumps.



Interesting. I can't imagine how you are correct. Especially if you are jumping a non-vented canopy. If you take a short delay, which was the discussed situation (lets assume a 1 sec delay- 16fps down, 20fps forward, roughly 45 degrees), the relative wind vector will be from behind, coming from your feet to head. As opposed to the head to toe, eg. nose towards tail.

You don't think that air rushing into the nose would increase the speed of opening relative to air rushing past the tail, past the nose, until the overhanging nose gets to scoop some of the air that is "relatively" outflowing past the nose?

And yes, everything causes lineovers. But I would assume that all things being equal, air blowing hard from the tail lines of the canopy towards the nose would have a much higher incidence of lineovers than the nose inflating first, which is exactly what the tailgate is supposed to promote. It is the tail lines that are most likely to cause a lineover, btw. Deployment position is different than the relative wind that the wind will react to once it hits the air.

I am very interested to hear your rationale in why a tailwind would open the same as a headwind. Since the canopy is opening, and inflating, at only the nose. (non-vented, and to a lesser degree vented.). And how lines that are getting blown towards the nose can't create a problem on opening.

Kind of makes me wonder if it would make a difference according to your thinking, if you were on the Prine with 20+ winds, whether you floated it or just hucked it normal. Same thing, same opening, no difference at all?
Gravity Research Institute

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IMO the wind (whether a tailwind or headwind) will affect your opening speed almost nil. in my experience, the canopy is like a windsock and will simply follow you in freefall at an angle with the direction of relative wind.

air will rush into the nose from below the canopy, not necessarily in front, as per design and line trim. so whether you do a floater or normal exit, the canopy should open the same.

to picture it...

floater = belly to relative wind, canopy comes off your back with the wind

a regular exit (may end up being slightly head down on a shorter delay to get belly to relative wind) = canopy still opens off your back with the wind.

even if you take a 1 sec delay, where you'll be traveling somewhere around 20mph in freefall, you will still be accelerating during opening, which dependent on PC deployment method, could be another few seconds of travel.

is this making sense?

maybe, i'm just crazy.:S

edited to add: stupid picture... what i'm trying to say (probably not so well) is that regardless of how you exit or where the wind is coming from, in "theory" the canopy will always open the same (disregarding heading) based on the fact that the "relative wind" will always hit the bottom of the canopy during deployment in the same manner (in a closed container deployment).

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IMO the wind (whether a tailwind or headwind) will affect your opening speed almost nil. in my experience, the canopy is like a windsock and will simply follow you in freefall at an angle with the direction of relative wind.



My experience with low freefalls very strongly disagrees with this. A headwind will cause you to open higher/faster, though the difference in opening speed will not be very obvious. The difference in opening height will be obvious.
A waddling elephant seal is the cutest thing in the entire world.
-TJ

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it gets complicated to think about, as in sub-term freefall, you are changing speed rapidly, and that has a factor in it.

but i think that like you said, its a windsock. the canopy is getting drug out by PC whatever direction the relative wind to the jumper is. so i dont think there is any difference in the amount of air hitting the nose of the canopy. it would be camparable to being head low or head high, thats it.

someone said that a headwind makes you open higher, (how so?)

are you jumping As in headwind, because that is the only way to prove this. jumping cliffs in a headwind only means that you accelerate in airspeed faster, not a headwind at all as the wind is comeing from beneath you on a cliff.

also, i can see how one would think that in a tailwind that a canopy takes longer to start flying if it is on heading opening, the body needs to be accelerated forward to wind speed as well as flying speed. but thats not opening.

-SPACE-

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are you jumping As in headwind, because that is the only way to prove this. jumping cliffs in a headwind only means that you accelerate in airspeed faster, not a headwind at all as the wind is comeing from beneath you on a cliff.

also, i can see how one would think that in a tailwind that a canopy takes longer to start flying if it is on heading opening, the body needs to be accelerated forward to wind speed as well as flying speed. but thats not opening.



Most of my data comes from a bridge, where jumping in a headwind is not a problem. There is a significant difference between a low freefall (where the wind will have the most effect on opening) in a tailwind versus a headwind. Myself and others have also jumped a certain antenna in a headwind, which I find to be within my limits of risk assuming certain precautions are taken.

The way I think it causes higher openings is what's been said before - a headwind will push air into the nose causing faster pressurization. Wind (in any direction) will also cause linestretch to occur faster due to faster overall speed relative to the air mass.

That is merely a hypothesis. I have made numerous observations, on video, showing that jumping in a headwind will result in faster primary pressurization than jumping in no wind or a tail wind.
A waddling elephant seal is the cutest thing in the entire world.
-TJ

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It sucks, but you might have to climb down from a tower



and then lay in the weeds till 5-0 steps away from your vehicle. haha. i love chiggers.


Rat for Life - Fly till I die
When them stupid ass bitches ask why

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ok, i have no research to support my theory.

i will have to test that someday.

i just dont understand from a physics standpoint...

the canopy MUST be at linestretch at paralel (or close to if teh PC is orbiting) the relative wind of the jumper, it only makes sense that way.

are you sure that your results are not skewed by holding back on high-tailwind jumps, and focusing then on high headwind jumps?

like you said, opening speeds first function is airspeed, and high wind increases that in sub-term.

maybe the headwind/higher relative wind is what your attributing these results to, not air going into the nose cell?

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I could see how tailwind could definitely slow down an opening.

While I agree with blitz in that until linestretch, the canopy acts like a windsock and opens the same relative to the wind, what about when inflation starts to occur?

For example, if the tailwind blows your canopy out in front of you during extraction, what happens when it hits linestretch and your body suddenly loads the canopy while it is in front of you? wouldn't it tend to pull the canopy backwards a bit (or at least exert some force preventing it from continuing to blow forward with the wind) to get it back over your head? Then while the canopy is inflating, the tailwind comes into play again, slowing down pressurization through the nose.

btw sorry if the above paragraph seems choppy or retarded, i'm driving down the highway with somebody talking my ear off and asking me to read off some stupid serial numbers, so each sentence was written about 5 minutes apart... hopefully you get the jist :)
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Cleveland Skydiving
"Hey, these cookies don't taste anything like girl scouts..."

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i just dont understand from a physics standpoint...

the canopy MUST be at linestretch at paralel (or close to if teh PC is orbiting) the relative wind of the jumper, it only makes sense that way.



try KITING your canopy.
does it inflate faster in a headwind or tailwind?
does it even want to inflate in a tailwind?

also, airfoils need airspeed to generate lift.
given a 10 knot wind, and 2 jumpers... the headwind jumper starts with a 20 knot airspeed advantage over the tailwind jumper. which will generated lift faster?
DON'T PANIC
The lies in learning how to throw yourself at the ground and miss.
sloppy habits -> sloppy jumps -> injury or worse

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slider down or slider up?

slider down - canopy inflation is from the bottom skin. the dynamic is completely different now with the advent of the tailgate.

slider up and without a slider gate mechanism, the tail wind will increase the rate of the initial opening but it may affect your heading.

slider down, slider up subterminal, and slider up terminal are completely different beasts. any generalizations regarding openings need to be put in context.
Looks like a death sandwich without the bread - Steve Deadman Morrell, BASE 174

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