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Modern (plastic) gliders are painted white (I suppose for thermal reasons), except for some shapes on the fuselage (generally blue or red, but it seems the color does not matter). And the aircraft registration is dark, I suppose for maximizing the contrast.

Now, for the wingtips I noticed that there are two possibilities:

  • white (nothing special)
  • red marks

My question is: Why red? Is there something special that is preventing the wingtips from being painted in another color?

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  • $\begingroup$ If one was red and the other was green I'd say it is to match the navigation lights. $\endgroup$ Commented May 11, 2017 at 9:44
  • $\begingroup$ I instantly googled other colors en.wikipedia.org/wiki/Wingtip_device#/media/… $\endgroup$
    – Fattie
    Commented May 11, 2017 at 12:30
  • $\begingroup$ Additionally, many sailplanes seem to be a light yellow color, some are orange, and here's one s-media-cache-ak0.pinimg.com/736x/47/d6/74/… $\endgroup$
    – Fattie
    Commented May 11, 2017 at 12:33
  • $\begingroup$ Other colours than red are used too. Our club has two ASK-21s; one with red markings and the other with blue markings. $\endgroup$ Commented May 11, 2017 at 14:33
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    $\begingroup$ They are not painted red. They are just very sharp, and ground personnel sometimes isn't. $\endgroup$ Commented May 11, 2017 at 20:30

3 Answers 3

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White is indeed chosen for thermal reasons. Gliders use epoxy resins which cure at room temperature and are then tempered at 60°C. This tempering shifts the glass transition temperature to something close to the tempering temperature, so the structure must not be heated under stress to more than this temperature. To limit heating by solar radiation, black surfaces should be avoided altogether and mostly red, blue or grey is used for markings.

The red wingtips were popular in the 1970s and were meant to improve visual identification when flying in hazy weather and close to clouds. They can be mostly found on gliders of this era. Since structural loads are lowest at the extremities, wing- and fuselage tips can be painted in high-visibility colors.

Schempp-Hirth Cirrus

Schempp-Hirth Cirrus with red wingtips but no markings (picture source). This makes it obvious that this is a British glider.

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    $\begingroup$ kind of off topic, but curious -- the lack of markings indicated British origin? $\endgroup$
    – cat
    Commented May 11, 2017 at 12:45
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    $\begingroup$ Everyone knows that red ones are faster! If you disagree, I'm sending the waaagh against you. $\endgroup$
    – Pierre
    Commented May 11, 2017 at 14:40
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    $\begingroup$ @cat: By Gentleman's agreement, the British authorities do not require markings, and the glider pilots behave responsibly, so there is no need to track miscreants down. And it works! $\endgroup$ Commented May 11, 2017 at 16:44
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    $\begingroup$ @BoundaryImposition I think the definition of "Gentleman's agreement" as an informal and legally nonbinding agreement is understood without virtue signalling... $\endgroup$
    – Zoey Green
    Commented May 12, 2017 at 2:35
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    $\begingroup$ @Pierre. I agree. Everyone knows red adds, like, 10hp. $\endgroup$
    – acpilot
    Commented May 12, 2017 at 13:05
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Personally speaking I like red wingtips because it makes seeing the wingtips a lot easier.

During a winch launch it is critical to keep the wings level which is easy in mid flight as you have a lot of time to look about and check the instruments, on the ground run of a winch launch (where fatalities do occur) the instruments are useless due to the bumping and you have no time to check anyway. Having the red wingtips means that you can see them in peripheral vision with a minor turn of the head.

Once off the ground in the launch, again it is important to keep level, there is no horizon (actually there is but it is underneath the aircraft and useless) and the horizon indicator may still be wobbling and takes time to check. Peripheral vision and red wing tips win through again. Most of my club gliders have red wingtips but some have fluorescent colours.

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    $\begingroup$ I strongly believe it's for security reasons to see the glider from longer distance. Anything that maximizes the contrast will do. We have a twin with blue strips, a Ka-8 painted with green strips (ok, that's not plastic..) $\endgroup$
    – gusto2
    Commented May 11, 2017 at 9:26
  • $\begingroup$ Maybe this is an ignorant layman question, but how does seeing the wingtips help keeping the plane level when there is no horizon as reference? The two times I've experienced a winch launch I had the feeling that my vestibular system wasn't much use. :) $\endgroup$
    – Emil
    Commented May 12, 2017 at 6:31
  • $\begingroup$ @Emil. Humans can tell what is up instinctively, we have a built-in gravity sensor that is fairly accurate. We can all sit up straight. Looking out at right angles is also fairly simple for most people. In launch I can look out at right angles to gravity and if one wingtip is at a different height to the other then I can correct it. Once the cable is off and you are free to bank and turn then the real horizon is better as the centripetal force confuses the body. On the ground run you can compare the wing tips against the ground. $\endgroup$
    – AndyW
    Commented May 12, 2017 at 7:55
  • $\begingroup$ As a side note: the color authorized by mfg for painting is on the manual. Usually is somehow contrasting color for registration and a few super-visible colors for wingtips etc. Fuselage is only to be painted in white except for some (rare) exceptions where orange or yellow is homologated. $\endgroup$ Commented Oct 10, 2019 at 7:41
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Additionally reflective red or orange markings are required in Sweden when flying in winter conditions in the mountain areas. Stockholm segelflyg tradionally goes up North to Ottsjö, a bit outside Åre, for flying. Starting and landing on the lake ice. They (sadly I never made it there) fly in the upwinds created above the mountains when the wind comes from the right direction. Oxygen is used and I believe a few has reached 10.000 meters. It is supposed to be spectacular flying in wind rotors. Cold as well.

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