Aces High Bulletin Board
General Forums => The O' Club => Topic started by: Sandman on August 18, 2009, 12:26:52 AM
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Never heard of such a thing before, but it looks bizarre. The photo is from Afghanistan.
Many more images here (http://www.michaelyon-online.com/the-kopp-etchells-effect.htm).
(http://www.michaelyon-online.com/images/stories/koppetchells/3150-fertilizer22vC-730.jpg)
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Ive seen this on our birds every once in a blue moon. Ive only seen it last for a few seconds. The best chance we have is when theres a thunderstorm and were in T1. Very cool looking. Thanks for the post, now I can sound smart to the booters when they ask what it is.
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If you asked me out of the blue I would have said the rotors were fixing to have a bad day. In fact it almost looks like the rotors came un-synced or something. Such a phenomena would have been my last guess, if I even got that far. Goes to show you all the weird things that we have yet to understand completely.
Edit: The camera used to take these photographs is phenomenal, in a few you could even see the exhaust housing glowing a red hue.
Thanks for posting this!
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It is a nice camera.. Wonder what it is. There's no exif data.
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That's pretty cool. I wonder if it's not just the rotors creating their own St Elmo's Fire like you get on the skin of aircraft when they fly near electrically charged thunderclouds.
http://www.youtube.com/watch?v=nx_vFXd_zpk
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In reading the article, you will understand Yon made up the name to describe the effect. It's a good read.
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Great article and it is quite touching to think that the name for the effect that is very cool was given in rememberance of two men who died among friends.
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Seen it many times, firsthand.. Usually in a rainstorm, but very high humidity will do it too...
I've seen CH 53's make a solid disk of yellowish/white fire in the spray, from the rotor downwash..
At night, standing, or floating, underneath it is spectacular without a doubt...Never seen it in
sand before, but it doesn't suprise me.. Apparently anything that can generate enough friction
on the blades, to build up the charge, will do it... Always called it St.Elmo's Fire...
Unless this is supposed to be a different phenomenon... Sure looks the same tho!!!
:aok on the new name for it... That's the best kind of reason to rename something!!!
RC
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In reading the article, you will understand Yon made up the name to describe the effect. It's a good read.
I did read the article, and I do understand he made up the name. However, the effect probably already has a name: St Elmo's Fire. And yes, it was a good read.
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It is a nice camera.. Wonder what it is. There's no exif data.
Well, it's clearly a digital camera. He was definitely shooting at a high ISO setting, 1600 or higher. Probably more like 3200. Even the best digital SLR cameras produce a "noisy" image at ISO settings above 800. By noise, I mean the red and blue flecks throughout the image.
I don't know who Michael Yon is, but if he is a journalist working in Iraq, he is almost certainly shooting either a Canon EOS1D Mark2 (or Mark3) or whatever the latest and greatest Nikon body is these days (shoot Canon myself, so I don't keep track of the Nikon equipment).
You can pick up a Canon 1D Mark3 for a little less than $4k these days, without a lens.
http://www.bhphotovideo.com/c/product/484813-REG/Canon_1888B002_EOS_1D_Mark_III_10_1.html
They make a 1D that shoots a higher resolution, but this model of the 1D has the faster frame rate, which is what a working photo journalist generally prefers. As for the lens, probably an 80-200 f2.8 IS. That's a popular lens for a journalist, it isn't very bulky or heavy (like a 300 f2.8 would be, which is usually considered a sports lens), but it has some reach and the f2.8 gives you a lot of lighting flexibility.
http://www.bhphotovideo.com/c/product/544676-USA/Canon__70_200mm_f_2_8L_IS_USM.html
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It's just static electricity created by the rotor blades. Very common to see at night. Usely under NVG's. Every rotor crafts does this.
Former Army Blackhawk Crew Chief and Inspector.
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It is similar to the balls of blue light emmitted in the wake from rotors of a ship ( or small boat I suppose also ) at night (daytime also but it's like the stars). I have tried to find pictures but can't find any. Can be quite mesmerising.
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It is similar to the balls of blue light emmitted in the wake from rotors of a ship ( or small boat I suppose also ) at night (daytime also but it's like the stars). I have tried to find pictures but can't find any. Can be quite mesmerising.
No. St. Elmo's Fire is from static electricity. The light from ship's wakes is a response of luminescent plankton to quantifiable levels of flow agitation. (Bioluminescence)
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That be cool for Independants day celebration. :aok :lol
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Seen it many times, firsthand.. Usually in a rainstorm, but very high humidity will do it too...
I've seen CH 53's make a solid disk of yellowish/white fire in the spray, from the rotor downwash..
At night, standing, or floating, underneath it is spectacular without a doubt...Never seen it in
sand before, but it doesn't suprise me.. Apparently anything that can generate enough friction
on the blades, to build up the charge, will do it... Always called it St.Elmo's Fire...
Unless this is supposed to be a different phenomenon... Sure looks the same tho!!!
:aok on the new name for it... That's the best kind of reason to rename something!!!
RC
Best guess, based on your observ and the photo: it's reflections coming off the water that has condensed out of the air in the vicinity of the rotor. Typically, any airfoil moving through freestream has a pressure distribution on its upper surface that gets pretty low (usually peaks near some point around quarter chord - see Abbott and Von Doenhoff if you want examples).
In any case, reducing the pressure will tend to create precipitation of any suspended water. It'll precip out, likely fogging/coating the blades. I suspect then that if the light hits it just right you'd see a reflection.
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sand and dust makes sparks on the blades. Saw it frequently during my 10 years as a CSAR helicopter flight engineer
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Okay... my guess looks bad. This is metal-on-quartz sparking or static discharge? If the latter, is it continuous or does it pulse (a bad question, I guess, since, itf it pulses at a high enough freq, it'll look continuous anyway).
But will it do it with a composite rotor as on AH-1W?
And how do you account for it happening in high-humidity conditions? That would look to favor static discharge as opposed to sparking...
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I also note, it only appears to be happening out near the tips - where the velocity is highest.
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chem lights look cool when thrown into the rotor system......nice green spray.
I have seen it happen on NVGs at night whenever we were in a hover, sand and dust seemed to amplify it.....so I guess it could be a little of both.