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Feb 07, 2012, 03:08 PM
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aeronaut999's Avatar
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Discussion

Colors for long-range visibility in the sky-- why red?


I notice that some of the high-performance molded sailplanes have a mostly-red undersurface, and red tips on the top surface. Is this really a good choice? It seems to me that a black undersurface would be much easier to see against the bright sky. The outer 1/4 or so of the underside of each wing could be white for added contrast.

Likewise for the top surface, it seems like a better choice might be white with black tips, rather than white with red tips.

I've always preferred to fly with polarized, brown lenses. These really seem to bring out contrasts in the sky to an amazing level. By tilting the head in various directions, one can brighten or darken the backdrop of the sky at will, like twisting a "brightness" setting. If the sky is "set" to dark, then all the white parts of a sailplane really leap out at the viewer. Conversely, if the sky is "set" to bright, then the black parts are very visible. That's why I like to have at least 25% of the glider as seen from any given direction be black, and at least 25% of the glider as seen from any given direction be white. Another important point is that the white areas and dark areas be as consolidated as possible into a few wide bands of color, not dispersed out into multiple stripes. (From a great distance a zebra might look grey!)

It seems to me that through red, orange, or brown lenses, red tones would act too much like white, being preferentially transmitted, and thus not giving the desired darkening effect. In some conditions, seen through these lenses, a red and white sailplane would be too much like an all-white sailplane -very easily seen in some conditions but very hard to see in other conditions, like against a high sunlit haze or cirrus layer. A sailplane with ample black or dark blue on it would seem to be much easier to spot under these conditions.

Maybe the red gliders are preferred by those who prefer grey lenses rather than red or brown-- but I've always thought that the brown polarized lenses were hands-down the way to go for seeing detail in the sky...

What do you think?

PS I think the birds have figured this out a long time ago. The big soaring birds that need to be seen at great distances by others of their kind are black and white. Bald eagles, wood storks, pelicans, jabirus, whooping cranes, condors, and so forth.... There are (almost) no big red soaring birds!

PPS I believe that at least some-- and possibly many-- of these birds are known to have in their eyes oils, coatings, or structures that preferentially transmit red tones... "blu blockers" sunglasses picked up on this in their ads....

Steve
Last edited by aeronaut999; Feb 07, 2012 at 03:25 PM.
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Feb 07, 2012, 03:55 PM
Registered User
Steve:

I once commissioned a DLG with sequenced, gradually decreasing chord-wise stripes (in black). The idea was from RCDigest, and was supposed to promote judging height by how many stripes you could count. It sort of worked, but a DLG was too small for it to work well.

Anyway, the black-and-tan stripes (black paint and kevlar) didn't turn "brown" with distance. Rather, the stripes merged instead (which was the intent), and I could always count on seeing a bit of black against a cloud, or a bit of light against the blue.

Ironically, I have observed another aspect of the visibility issue. I flew two, matching DLGs last year that were kevlar with no distinguishing marks. Far away or high up, what was visible were the tail surfaces, "flashing" in the sun as the glider turned.

I do believe that the soaring birds see thermals - to a point. Last summer in Utah, we experienced an afternoon of really dead air. But, when two or more gliders started circling (one would circle, almost in hopes, and others would join), then soaring birds would join up for a turn or two. Then, depart.

Yours, Greg
Feb 07, 2012, 05:09 PM
Envies his own avatar
rockyabq's Avatar

Stadiametric ranging


This yours, Greg?
I tried a similar pattern on the bottom of my Weasel.

I found this on the web a while back...

"Now, don't anyone go copying this....

This is my new Light Speed from RCBuilder. The format and dimensions came from an old copy of RC Digest, and ASK did it for me special.

In the air, count the stripes.

6 stripes = < 200' away
5 = 200-400
4 = 400-800
3 = 800-1200
2 = 1200-1700
1 = 1700-2500
0 = over 2500' away

And yes, when I launch, I can still see all six stripes."

And from RC Soaring Digest for July 1998 (I think):

Dimensions: 6" stripe; 4" gap, 4" stripe; 3" gap, 3" stripe; 2" gap, 2" stripe; 1" gap, 1" stripe; 0.5" gap, 0.5" stripe.

What ever the colors you choose, I discovered that "dark" colors (red, blue, black) work best on "light" backgrounds (yellow, white).

And also yes about what someone said: beyond 1700 feet, you are not really controlling ANY glider, just trying to get it back, especially a DLG.
Feb 07, 2012, 07:58 PM
It's gonna be YUGE!!!
LVsoaring's Avatar
This question, or a variation thereof, has come up time and time again.

IMHO, the correct answer is, use whatever color works best for you. Everyone is different.

Personally for me, dark blue or purple works best against a light blue sky.
Feb 07, 2012, 08:03 PM
It's gonna be YUGE!!!
LVsoaring's Avatar
Another bit of info that may be of interest.....
Feb 07, 2012, 08:13 PM
Hot Dawg Glider Pilot
schrederman's Avatar
My easiest-to-see colors are white tops with orange trim, and blue/orange bottoms...
Feb 07, 2012, 09:28 PM
Sherpa
Schwemmer's Avatar
I read this article on Pierre Rondel's web site. He compares colors against the sky. Have a look.

http://planet-soaring.blogspot.com/2...contrasts.html

Hope this info helps.

Sherpa
Feb 07, 2012, 09:32 PM
Registered User
rockyabq:

Yes, that's me, and that's my trusty, old, long-gone Light Speed.

Yours, Greg
Feb 07, 2012, 10:00 PM
Registered User
Vegas_flyer's Avatar
Radian 78" wingspan, I was able to see it at 3500 feet, just a couple of dots but I could see it......


.... and the top was left solid white.
Feb 08, 2012, 01:30 AM
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aeronaut999's Avatar
Thread OP
Interesting-- I always thought that my orange translucent Gentle Lady was very easy to see in most situations, even when specked out very high overhead, with or without the brown polarizing lenses. Of course with that generous dihedral, discerning the orientation was rarely an issue, it was always obvious which side was "up"....

I still think that in a non-translucent, bi-colored aircraft, with modest dihedral, white and black might be the most visible color scheme, and in the interest of making the orientation obvious, the undersurface should be about 70% black and the top surface should be about 70% white....

I'm having a hard time believing that the bar-code-looking multi-striped color scheme is a good way to go....

And I'm still thinking that millions of years of evolution may have come up with something that is also pertinent to our more temporal needs....

Steve

Quote:
Originally Posted by Schwemmer
I read this article on Pierre Rondel's web site. He compares colors against the sky. Have a look.

http://planet-soaring.blogspot.com/2...contrasts.html

Hope this info helps.

Sherpa
Feb 08, 2012, 01:31 AM
Registered User
aeronaut999's Avatar
Thread OP
Quote:
Originally Posted by Vegas_flyer
Radian 78" wingspan, I was able to see it at 3500 feet, just a couple of dots but I could see it......


.... and the top was left solid white.
I bet you could have seen it at 4000' if you had consolidated the orange areas into one color patch on each wingtip rather than breaking them up with the black stripes...

Steve
Feb 08, 2012, 01:54 AM
Registered User
Vegas_flyer's Avatar
That might depend on which way it is turning.

Those victory stripes allways confused me. People clam they are highly visible, yet the say the stripes will incrementally dissapear the farther awy they get.

Quote:
6 stripes = < 200' away 100% wing showing
5 = 200-400
4 = 400-800
3 = 800-1200
2 = 1200-1700
1 = 1700-2500
0 = over 2500' away <50% of wing showing
How could that be more visible?
Feb 08, 2012, 09:46 AM
Envies his own avatar
rockyabq's Avatar
Yes, this is true. The graduated sizes of "invasion stripes" are not intended to provide maximum visibility. They're just an attempt to allow the flier to estimate the altitude of the plane. (Sorry for getting off-topic with that.)

Back on topic...
Around these parts, folks have been using what's coming to be called "Nutter panels" on their built-up wings. Most of the bottom of the wing is a dark color, but a section about a chord-length wide on one or both wings is covered--top and bottom--with translucent white covering. When that's illuminated by the sun, the white panel glows like it's lit up and is very easy to see at distance.
Feb 08, 2012, 10:44 AM
LSF303-AMA Fellow
tkallev's Avatar
Everyone's eyes are different, some people are more sensitive to red, some to orange or yellow ... it really depends on the individual.

IMHO, all colors bascially turn black on the bottom of a model when it gets to a certain altitude. My best colors for seeing are black on the bottom, red on the top with white stripes or white tips to give contrast on the top of the wing.

YMMV ...

tk
Feb 08, 2012, 03:57 PM
Registered User
ozmo01's Avatar
I got this pic here and saved it for a reference


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