What is TB #9 using?
Nah really, that is impressive.
Last edited by Beaker on Sun Feb 06, 2011 4:06 pm, edited 1 time in total.
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Signal Mirrors for Show Center
You're welcome. I was excited to see three photos of "show center" signal mirrors in a single thread.Gunner wrote:@SignalMirror - Wow! I don't believe I've ever seen a more informative and detailed explanation from one of our members! Thanks for taking the time to post that - very interesting stuff!
If any one else has similar photos, now or in the future, please post them. It will be hard to beat Rhino's photo, though.
By the way, there are over 500 photos tagged "Thunderbirds" at the US Department of Defense photo album here - good source for Thunderbird photos, and almost all are public domain (read the Terms of Use):
http://dodimagery.afis.osd.mil/imagery. ... 6cfe0&n=90
In contrast, that site has only 32 images tagged "Signal Mirror":
http://dodimagery.afis.osd.mil/imagery. ... 6cfe0&n=60
That does include one of a forward air controller using a seriously damaged mirror (click on the "+" icon under the thumbnail for a larger view, or click the download icon to the right of the shopping cart icon to download the full-resolution photo)
http://dodimagery.afis.osd.mil/imagery. ... 8af6edf6ee
Re: Signal Mirrors for Show Center
Most people are probably much more interested in the Thunderbirds than signal mirrors.SignalMirror wrote:In contrast, that site has only 32 images tagged "Signal Mirror"
Re: Signal Mirrors for Show Center
I'm flattered, but I dunno. This is hard to beat:SignalMirror wrote:If any one else has similar photos, now or in the future, please post them. It will be hard to beat Rhino's photo, though.
Phantoms Phorever!
Re: Signal Mirrors for Show Center
When 2 million candlepower just isn't enough...use 6!Rhino wrote:I'm flattered, but I dunno. This is hard to beat:
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Re: Signal Mirrors for Show Center
I'm pretty certain you are right about that.Beaker wrote:Most people are probably much more interested in the Thunderbirds than signal mirrors.SignalMirror wrote:In contrast, that site has only 32 images tagged "Signal Mirror"
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Re: Signal Mirrors for Show Center
Wow.Rhino wrote:I'm flattered, but I dunno. This is hard to beat:SignalMirror wrote:If any one else has similar photos, now or in the future, please post them. It will be hard to beat Rhino's photo, though.
Okay, I did not expect that.
However, that does make my statement that "it will be hard to beat Rhino's photo" even more true.
That looks like Major Charla Quayle holding three military issue 3"x5" mirrors on a common mount. Great photo angle, too - nice job, and Thanks!
I'm wondering what they are using these days - the "three-pack", or the 4"x5" size. Based on the dates, I'm thinking they went back to using the 4"x5" size.
That composite signal mirror reminds me of the four-panel signal mirrors the Varsity Scouts build for 100+ mile mirror signaling for their "Operation On Target" mountaintop signaling event:
Also, I looked at your photos on Flickr - nice work!
Actually, that assembly she's holding is more in the 45 million candlepower class.Teej wrote:When 2 million candlepower just isn't enough...use 6!
Re: Signal Mirrors for Show Center
Heh. Nice. I think for something like that, I like the "Mythbusters" aiming technique (from the last "death ray" trial).SignalMirror wrote:That composite signal mirror reminds me of the four-panel signal mirrors the Varsity Scouts build for 100+ mile mirror signaling for their "Operation On Target" mountaintop signaling event:
Basically they stretched a loose net (the net looked a lot like cyclone fence sized mesh) about 30-40 feet away from the mirror, in the direction of the target. Aim your mirror such that it lights up the net, centered around your target (which you can see through the net).
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Re: Signal Mirrors for Show Center
I missed that show, darn it. I guess I'll have to wait for the DVD.Teej wrote:Heh. Nice. I think for something like that, I like the "Mythbusters" aiming technique (from the last "death ray" trial).SignalMirror wrote:That composite signal mirror reminds me of the four-panel signal mirrors the Varsity Scouts build for 100+ mile mirror signaling for their "Operation On Target" mountaintop signaling event:
Basically they stretched a loose net (the net looked a lot like cyclone fence sized mesh) about 30-40 feet away from the mirror, in the direction of the target. Aim your mirror such that it lights up the net, centered around your target (which you can see through the net).
You certainly can aim a mirror by lining up something between you and the target, then lighting it up, and it is a decent method if you know the right technique (below), but it is a lot tricker than you might think.
There's a reason Thunderbird #9, the Blue Angel, and the Snowbird are all using the aiming mesh rather than the manual equivalent of the net (the "Vee-finger" method, where you hold up two fingers outstretched in front of the mirror in a "Vee" shape and center the beam on them in similar fashion to the way the net was used above).
The reflected sunbeam is very narrow - that's why it is so bright. The angular diameter at long range is 0.54 deg in diameter, the apparent diameter of the sun. Every speck of silver in your mirror is putting out a cone of light 0.54 deg in diameter, and to line up with a long range target, you need the line from your eye to the target to be parallel with the line from a speck of your mirror to its corresponding part of the near-field beam (40 ft away, in your example) to the radius of the beam, or 0.27 deg. At 40 ft range, that is 2.25 inches.
The only time your correct "sight picture" is to have the target centered on the glowing spot on that mesh is when the line from your eye to the center spot in the glowing mesh is the same as the center point of your mirror to that mesh. That's true if you are looking through a hole in the center of the mirror, but if it isn't, you are going to be way off target due to parallax error.
If your target is nearly as close as the mesh, and you have a nice wide mirror, you may luck out, but at long range - nope.
For long range using an aiming post 40 ft away, a good method is to line up your eye, a corner of the mirror, the corresponding corner of the light beam on that object 40 ft away, and the target. If you can do that (to the 2.25" accuracy), you are, as the scouts say, "On Target".
Bottom line: the Thunderbirds get their money's worth out of the signal mirror aimer mesh, it makes the job a lot easier. Even with the mesh, it takes care. Just getting the aimer "fireball" (that glowing spot on my graphic avatar icon) on the target doesn't guarantee a hit - you really want to pass the very center of the "fireball" across the target.
(Another method that works well (on dry land, anyway) is to put a hole in the mirror, look through the hole, and line up your eye, the center of the mirror hole, the center of the shadow cast by the mirror hole (on a fingertip), and the target. My friend had no problem flashing me at 22 mile range with that method).
Sooo ... that's why US pilots (and not just the Thunderbirds / Blue Angels) have been issued mirrors with retroreflective aimers since the 1950s, and at I know that pilots in at least France, the Netherlands, Italy, Switzerland and China are issued mirrors with retroreflective aimers, too. (Not that I wouldn't take a (working) radio over a signal mirror in a heartbeat if I were ditched in the ocean).
[For more on signal mirrors, here are two signal mirror galleries: http://www.richard-fowell.fotopic.net/c1663439.html (with reference links) and http://commons.wikimedia.org/wiki/Categ ... al_Mirrors (with lots of description and mouseover annotation on the individual photo pages).]