Visible wingtip vortex!

See Bill? I was right! It was a ghost!
Jim

On Mon, 24 Oct 2005 13:46:08 -0500, "Jim Burns"
wrote:

See Bill? I was right! It was a ghost!
Jim


Yeah, that sounds just as reasonable, just like those spirits that
mock me by yelling back at me. For some reason, those spirits are
always around certain canyons and caves.

I'll get this ghost on video before the end of the year, hopefully.

I just couldn't believe I had never heard of this being visible,
especially with the number of people who fly formation for recreation.

Bill Strahan
------------
Find a new reason to fly
www.adventurepilot.com

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"Bill" wrote in message ...
Yesterday I was flying back from a weekend camping trip, and came up
behind my friend in his AA5. I started getting up close, and was
feeling the effect of the vortex off his right wingtip. I reached the
point that I had my ailerons deflected almost 50-60% to the right just
to stay level, when I suddenly SAW the vortex hitting my windshield!

I know if I heard this description I would say it was bull****. But I
saw it, as did my passengers. It was a tube of swirling distortion,
dropping down off his wingtip and then coming back to us. At that
point, I had rolled out of position, and was way off to his right. My
passengers all wanted to see it again, so we dropped behind and
started closing in again.

Imagine the way heatwaves createa a shimmering effect. It was the
same thing, except it was swirling instead of shimmering. We saw it
twice more, and it was a lot of work to do it. There is a VERY narrow
cone behind the wingtip in which it's visible, and it's very difficult
to stay in one position while the vortex is essentially centered on
the windshield.

We all tried to describe it in words, and the bottom line is it looked
like some strange special effect from a movie. Words like "wormhole"
were thrown around. But if I had seen this in a movie I would have
said it was bull**** and complained about directors making up crap
just for special effects.

So, I'm going to try to duplicate this at some point, and video
tape.it. The sun was in front of us, and that may have played a part,
but I'll find a way to duplicate it and get it on video.

When I do, I'll post it on my site and I'll announce it here as well.

Anyone else actually seen the wingtip vortex like I'm trying to
describe?


Bill Strahan
------------


Where was the sun relative to your view? There is an effect called a "schlieren visualization" that describes why we see
mirages and the like, sort of like seeing the heat rise off a candle. I once watched a shock wave dance around on the
nacelle of a DC-10. The sun was the "coherent light source" low on the horizon. It was pretty strange to see. I have
also read that NASA and DARPA have used high power optics from the ground to observe airflow around an aircraft at high
altitudes.

Dan D.

On Mon, 24 Oct 2005 18:56:44 GMT, ".Blueskies."
wrote:


"Bill" wrote in message ...
Yesterday I was flying back from a weekend camping trip, and came up
behind my friend in his AA5. I started getting up close, and was
feeling the effect of the vortex off his right wingtip. I reached the
point that I had my ailerons deflected almost 50-60% to the right just
to stay level, when I suddenly SAW the vortex hitting my windshield!

I know if I heard this description I would say it was bull****. But I
saw it, as did my passengers. It was a tube of swirling distortion,
dropping down off his wingtip and then coming back to us. At that
point, I had rolled out of position, and was way off to his right. My
passengers all wanted to see it again, so we dropped behind and
started closing in again.

Imagine the way heatwaves createa a shimmering effect. It was the
same thing, except it was swirling instead of shimmering. We saw it
twice more, and it was a lot of work to do it. There is a VERY narrow
cone behind the wingtip in which it's visible, and it's very difficult
to stay in one position while the vortex is essentially centered on
the windshield.

We all tried to describe it in words, and the bottom line is it looked
like some strange special effect from a movie. Words like "wormhole"
were thrown around. But if I had seen this in a movie I would have
said it was bull**** and complained about directors making up crap
just for special effects.

So, I'm going to try to duplicate this at some point, and video
tape.it. The sun was in front of us, and that may have played a part,
but I'll find a way to duplicate it and get it on video.

When I do, I'll post it on my site and I'll announce it here as well.

Anyone else actually seen the wingtip vortex like I'm trying to
describe?


Bill Strahan
------------


Where was the sun relative to your view? There is an effect called a "schlieren visualization" that describes why we see
mirages and the like, sort of like seeing the heat rise off a candle. I once watched a shock wave dance around on the
nacelle of a DC-10. The sun was the "coherent light source" low on the horizon. It was pretty strange to see. I have
also read that NASA and DARPA have used high power optics from the ground to observe airflow around an aircraft at high
altitudes.

Dan D.


The sun was ahead, and above the wing. Not so bad that it was
blinding us though. If I had to guess....draw a line from us as
observer to the wingtip. The sun was 20-30 degrees higher than that.
It definitely wasn't close to head on.

FWIW, this was about 5:30 yesterday, Paris, Tx area.

Bill Strahan
------------
Find a new reason to fly
www.adventurepilot.com

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A great example of this is when the space shuttle lands, particularly at
Edwards (at KSC it tends to be humid so water vapor forms in the vortices
and masks the refraction). I've noticed it a few times and it is mainly
visible in video pointed right down the runway. Super high wing loading, I
would guess. I searched for a while but could only come up with one decent
video showing the phenomena. Pictures don't really demonstrate it. This
video is in quicktime *.mov format, so my apologies if you can't view it.

http://www.fotosearch.com/comp/FIL/FIL101/EV0116.mov

The physics of it are just those of compressible flow. Change in density
leads to change in the index of refraction of the gas. Visible, as someone
else said, via the Schlieren optical system often used in
transonic/supersonic wind tunnels. I've seen such a setup in action at the
supersonic tunnel at my school. Pretty cool stuff.

http://www.ae.su.oz.au/aero/super2d/ssflow3.html
http://web.mit.edu/edgerton/people/v...schlieren.html


-Tony Goetz
Rocket scientist in training.

In article ,
Bill wrote:

On Mon, 24 Oct 2005 13:06:38 -0500, "Jim Burns"
wrote:

Ahhh... nope. Haven't ever seen that. Sounds like a ghost though. Spooky.

Visually identifiable compressed air held together by centrifugal force
traveling through relatively less compressed air?

Jim


It WAS spooky. I don't understand how heatwaves are visible, nor do I
understand how this was visible. There were four of us in that plane,
completely dumbfounded each time we say it. It was so strange, we
were squealing like schoolgirls when we saw it the second time.

What causes distortions from heatwaves? Is it the differing density
of the air? If so, that might start to explain it.

Start he

http://en.wikipedia.org/wiki/Refraction

rg

Morgans wrote
A great example of this is when the space shuttle lands, particularly at
Edwards (at KSC it tends to be humid so water vapor forms in the
vortices
and masks the refraction). I've noticed it a few times and it is mainly
visible in video pointed right down the runway. Super high wing loading,
I
would guess.

I had always thought that was mainly due to the fact that the air coming
off
the bottom of the wing was hot as **** from re-entry. Perhaps some of
both?
--
Jim in NC


The effect only seems to be visible where the wingtip vortices would be, so
my guess would be that it's at least mostly due to them. As for the tiles
being as hot as ****, I don't think it's unusual for the ground support guys
and even the crew to wander around the shuttle not long after landing, even
touching the tiles, so I doubt they're still too hot. The tiles work by
storing the energy of re-entry within the material without raising their
temperatures too much. At the aerodynamic surface of the tiles the
temperature does get up into the thousands of degrees due to the shock
heating, but by the time the shuttle touches down they've likely cooled to
somewhat just cooler than ****.

But those are just my thoughts and possible unreliable memories of photos
and video. I hope someone corrects me if I'm wrong.


-Tony "I'm not an aerospace engineer yet but I play one on TV" Goetz

"Bill" wrote

Yesterday I was flying back from a weekend camping trip, and came up
behind my friend in his AA5. I started getting up close, and was
feeling the effect of the vortex off his right wingtip. I reached the
point that I had my ailerons deflected almost 50-60% to the right just
to stay level, when I suddenly SAW the vortex hitting my windshield!

I know if I heard this description I would say it was bull****. But I
saw it, as did my passengers. It was a tube of swirling distortion,
dropping down off his wingtip and then coming back to us.

You are the first I have ever heard describe this. Interesting. I would
think that there was a little moisture component along with the density and
diffraction, but perhaps not.

They say the late NASCAR race car driver, Dale Earnhart, could see "the
draft." His success at the highest speed tracks, where the draft was the
most important, would seem to make you think that he had something extra
working for him. Your account makes me give more credence to that legend,
now. Thanks for posting.
--
Jim in NC

"Tony Goetz" wrote

A great example of this is when the space shuttle lands, particularly at
Edwards (at KSC it tends to be humid so water vapor forms in the vortices
and masks the refraction). I've noticed it a few times and it is mainly
visible in video pointed right down the runway. Super high wing loading, I
would guess.

I had always thought that was mainly due to the fact that the air coming off
the bottom of the wing was hot as **** from re-entry. Perhaps some of both?
--
Jim in NC

"bill" == bill writes:

bill On Mon, 24 Oct 2005 12:50:20 -0500, "Jim Burns"
bill wrote:

Not the wingtip vortices, but prop wash vortices. On very
humid days, we can see them swirl past the cabin of our Aztec
on take off roll. I've also seen them many times watching crop
dusters take off. Jim


bill I've seen that as well, but it's visible from every angle.
bill It's essentially a small cloud created at the tip of the
bill prop.

This brings up a question. Why don't we experience the same
distortion all the time behind our single-engine props? Surely that
distortion would be more than what you saw, yet I've never noticed
anything like it. Maybe the distorted tube of air is too short (a few
feet) whereas your wingtip tube was many feet?