We already have two new AF-Ones on order from Boeing for $3.9 billion

[Igel]

10. I heard this here a couple of weeks ago.

Periodically dig.

One claim was that the dark paint has more air resistance. Counter: Perhaps--only "perhaps"--50 years ago. But not now.

Claim: "There's a reason that birds and such are light underneath. It's so they're not visible from below." Counter: Same for fish. On the other hand, it's not like there's an active campaign to spot and destroy civilian (or government/military) aircraft. Plus that wasn't a claim, just an observation.

Claim: "You don't want heat absorbed on the bottom, that's why the top's darker." Counter: But the Sun's going to be hotter than the IR emitted by the ground. In addition, blackbodies cool faster than more reflective bodies, with black being the easiest crude approximation of a blackbody. If there's a worry about heat from below, dark would be best below. But the claim's the flip of that.

One could claim, plausibly, that you'd want the top of the plane dark so it would cool faster when the Sun went down (but pity the HVAC during the day--thankfully, most flights are at night ... Oh ... Wait ....) Polished metal would be the worst "color" for cooling. There you have it. (Actually, white titanium-based paint, if smooth, might be good. Emits in the IR.)

Plus it's not that the claim that the bottoms of planes are conventionally all light isn't fairly sieve-y. Apparently during WWII they were painted dark to help other pilots spot them. Otherwise ...

https://www.smithsonianmag.com/air-space-magazine/why-do-airliners-have-dark-bellies-64155827/
https://www.airlinereporter.com/2011/12/why-is-american-painting-the-bottom-of-their-planes/
https://aviation.stackexchange.com/questions/1833/why-are-airliner-underbellies-generally-painted-differently