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#1
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Visible wingtip vortex!
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 ------------ Find a new reason to fly www.adventurepilot.com ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
#2
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Visible wingtip vortex!
On Mon, 24 Oct 2005 12:25:15 -0500, Bill wrote in
:: It was a tube of swirling distortion, dropping down off his wingtip and then coming back to us. Did what you saw have any moisture component that made it more visible? |
#3
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Visible wingtip vortex!
On Mon, 24 Oct 2005 17:36:15 GMT, Larry Dighera
wrote: On Mon, 24 Oct 2005 12:25:15 -0500, Bill wrote in :: It was a tube of swirling distortion, dropping down off his wingtip and then coming back to us. Did what you saw have any moisture component that made it more visible? No. We discussed this as well. This was nothing like the vortices you see when it's humid, especially from jets on landing. This was just a visual distortion, like what would happen if you looked through glass that had a big dimple in it. And if you weren't almost perfectly centered on it, it was invisible. You could not see it from the side of the plane, nor from behind it unless the center of the vortex was actually hitting the windshield. Bill Strahan ------------ Find a new reason to fly www.adventurepilot.com ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
#4
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Visible wingtip vortex!
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 |
#5
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Visible wingtip vortex!
On Mon, 24 Oct 2005 12:50:20 -0500, "Jim Burns"
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 I've seen that as well, but it's visible from every angle. It's essentially a small cloud created at the tip of the prop. This was absolutely invisble unless you were centered behind it. Then you got a distorted view of everything through it. It wasn't white, it was clear. Bill Strahan ------------ Find a new reason to fly www.adventurepilot.com ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
#6
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Visible wingtip vortex!
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 |
#7
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Visible wingtip vortex!
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. Bill Strahan ------------ Find a new reason to fly www.adventurepilot.com ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
#8
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Visible wingtip vortex!
"Bill" wrote in message
... What causes distortions from heatwaves? Is it the differing density of the air? If so, that might start to explain it. Bill Strahan I've never heard any "official" explanation from an expert, but that's been my understanding. Different air density bending light waves differently than the surrounding air. Jim |
#9
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Visible wingtip vortex!
In article ,
Bill wrote: On Mon, 24 Oct 2005 17:36:15 GMT, Larry Dighera wrote: On Mon, 24 Oct 2005 12:25:15 -0500, Bill wrote in :: It was a tube of swirling distortion, dropping down off his wingtip and then coming back to us. Did what you saw have any moisture component that made it more visible? No. We discussed this as well. This was nothing like the vortices you see when it's humid, especially from jets on landing. This was just a visual distortion, like what would happen if you looked through glass that had a big dimple in it. And if you weren't almost perfectly centered on it, it was invisible. You could not see it from the side of the plane, nor from behind it unless the center of the vortex was actually hitting the windshield. The index of refraction of air changes with density. Light moving between regions of different density gets bent by the changes in the IofR. You perceive this bending as distortion. This is what causes the "shimmering" effect on a hot day. Light moves from hot, less dense air near the ground to cooler, more dense air by your eyes and is refracted at the boundary between the two air masses. The shimmering occurs because the hot air rises, which causes the temperature and hence the density of the air to fluctuate. The effect is most pronounced where there is a net difference in density between the air around the observer and the object being perceived. In this case the light passes through only one refraction boundary. The light is bent only once, and so it arrives at the observer at a different angle than it left the object being observed, making it look as if the object has moved quite a bit from where it really is. (You can see this effect very dramatically in a fish tank.) If the density at the object and observer are the same you can still perceive refraction if there is more/less dense air in between, but the effect is much less. This is because the light passes through two refraction boundaries. The first one bends the light one way, and the second one will (typically -- it depends on the geometry) bend it back, so the net effect is not a change in the angle of the light but simply an offset. The magnitude of the offset depends on how far the light travels in the different density region. Because vortices are narrow the refraction offset viewed from the side is too small to be perceived by the unaided eye. But inside the vortex the light passes through only one refraction boundary so you get an angular offset that you can perceive. The "shimmering" is caused by small changes in the geometry of the boundary of the vortex as the plane moves through the air. rg |
#10
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Visible wingtip vortex!
"Bill" wrote in message ... 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. Same thing, Yes. |
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