Wind and Opening Heading

[TomAiello 26]

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Heck yea. You get one just "because its Wednesday." I had my first one a month ago. 900 A 6 second delay. Plenty of tail wind...

On a 6 second slider up delay, I'd say that the tailwind most likely caused that 180. It probably would have happened that way on Tuesday, or Thursday, as well, had the wind conditions been the same.

edit for thread title ~TA

-- Tom Aiello

Tom@SnakeRiverBASE.com
SnakeRiverBASE.com

[avenfoto 0]

can you elaborate? im not following something i guess... i can see (and have experienced)how a crosswind can influence opening heading, but was of the understanding that tailwinded a = good...

[VictorSuvorov 0]

cross/tail wind affects your openning on short delays(when your fall rate is comparable to the wind speed)because it changes your body position in relative wind. crude example: deploying at 30mph vertical speed with 30MPH cross wind and your sholders parallel to the groung is similar to having your sholder dipped 45 gegrees with no wind. another words the canopy will try to turn into the wind.
i donot see how tail wind would affect the oppening on 6 sec.

[TomAiello 26]

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I donot see how tail wind would affect the oppening on 6 sec.

For lack of a better term, I'd call it "windsock effect." The canopy (not yet fully inflated) has open cells at the front that tend to be grabbed by the wind and rotated in a manner similar to what happens to a windsock. This is more pronounced with slower openings (because there is more time before the slider gets down for the still-bunched-up canopy to get pulled around by the wind). Subterminal slider openings are pretty slow. This often yields openings directly into a strong wind (regardless of wind direction). I remember one load with a wind at opening of around 35-40 mph coming from approximately 135 degrees behind and left, on which 5 consecutive jumpers experienced identical 135 left openings.

-- Tom Aiello

Tom@SnakeRiverBASE.com
SnakeRiverBASE.com

[Tornolf 0]

Could that possibly be the cause of a 180 I had recently? I had to stop climbing a tower due to ice on the ladder and exited around 750 or so. I took around a 4 second delay and opened with my body in the harness onheading, the slider still up, and a 1/2 twist in the lines below the slider. I had little forward movement due to a decent wind (I'd estimate about 10-15mph direct tail wind from 200-450ft) and turned it around without incident.

I had considered something similar to this as the cause, but neither myself nor two more experienced jumpers I talked to could come to a definitive answer.

A waddling elephant seal is the cutest thing in the entire world.
-TJ

[sabre210 0]

Tom

Are you saying that this happens because a lot of the time what we consider to be tailwinds are actually not pure 180 tailwinds and so the canopy is turned from the dominant direction.

If it was a pure bona fide tail wind i can't understand how the wind could grab the cells at the front of the canopy and turn it one direction or the other. Surely all it can do is push.

Crosswinds on sub terminal slider ups are something i am very weary of but have laboured under the belief that a tailwind was not something that would affect my heading performance per se, and to a degree, this has been my experience.

Have you experienced the canopy getting pitched nose down (or rather tail lifted) and diving to the ground in tailwinds?

ian

[VictorSuvorov 0]

the windsock analogy does not really work, because the deployment take place in RELATIVE wind, the canopy isnot attached to the pole. i attachad a diagram to examplify. i apologize for the lack of artistic abilities. the perfect tail wind should not affect the headding. it was my experience as well

[The111 1]

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the windsock analogy does not really work, because the deployment take place in RELATIVE wind, the canopy isnot attached to the pole.

Here's a guess:

The canopy is attached to the jumper who, while not a pole, does have a great amount of inertia, and is not initially moving downwind at as great a speed as he will be once he is a "jumper/canopy system in equilibrium", especially if he is subterminal.

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[TomAiello 26]

I've split this off the "Cliff Strike in Arizona" thread.

-- Tom Aiello

Tom@SnakeRiverBASE.com
SnakeRiverBASE.com

[TomAiello 26]

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Are you saying that this happens because a lot of the time what we consider to be tailwinds are actually not pure 180 tailwinds and so the canopy is turned from the dominant direction.

Partly, yes.

But remember that the other side of the equation (the canopy heading) is rarely "pure" either. What we think of as "on heading" can be (and often is) up to 15 degrees off heading. Remember back in the IPBC days, when jumpers would complain that the judges had dinged them 10 degrees, even though they'd had a perfect on heading? And then when they were shown the video, they almost always had to admit that what they perceived as a "pure" on heading was actually 5 or 10 degrees off, one way or another?

-- Tom Aiello

Tom@SnakeRiverBASE.com
SnakeRiverBASE.com

[yuri_base 1]

Good illustration. While not about heading performance, here's another factor that should be taken into account: extra loss of altitude caused by canopy surging down in strong tailwind. This can make a low pull uncomfortably low.

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