4 ms·

> They were always white as that was part of the spec - dark colours would have taken heat absorption out of limit! Interesting. The SR-71 Blackbird was dark (

by msl 10y ago

> They were always white as that was part of the spec - dark colours would have taken heat absorption out of limit! Interesting. The SR-71 Blackbird was dark (almost black) in order to radiate heat efficiently [1]. Then again, the Blackbird flew much higher (at around 26 km compared to Concorde's just over 18 km) so maybe convection plays a bigger part in Concorde's thermal management. [1] https://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird https://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird (Although my primary source is the book "Skunk Works" by Ben R. Ritch and Leo Janos.)

chadgeidel 10y ago
Zing! I, too remember this from "Skunk Works". What a great book!
anexprogrammer 10y ago
Fascinating. Now I want to know why! Maybe at mach 3 more heat's coming from inside than being absorbed. Concordes were specced with Anti-flash White (high reflectivity as used by US and UK nuclear bombers), and the main reason I remember is there was some publicity when France painted one Pepsi blue (not wings) for a sponsorship. It had to have speed restrictions. Wikipedia has a little more (not much), but says the white finish reduced the skin temperature by 6 to 11 degrees Celsius. https://en.wikipedia.org/wiki/Concorde https://en.wikipedia.org/wiki/Concorde
- msandford 10y ago
  The sun adds 1000 watts per square meter, and black body radiation is the fourth power of temperature difference. If you're heating the skin say 5000 watts per square meter due to friction or compression, then the 1000 watts from the sun isn't bad. But if it's only say 500 watts, well, then the sun dominates. They operated at different speeds and altitudes so it's not entirely surprising to me that they had different strategies.
hga 10y ago
Note that they were using titanium, and while I'm not sure what the fuel cells were made of, until they heated up it leaked quite a bit. One of the first orders of business after takeoff was getting a refuel, which included changing the type of fuel, see e.g. http://iliketowastemytime.com/facts-you-didnt-know-about-sr71-blackbird http://iliketowastemytime.com/facts-you-didnt-know-about-sr7...

by msl 10y ago

chadgeidel 10y ago

Zing! I, too remember this from "Skunk Works". What a great book!

anexprogrammer 10y ago

Fascinating. Now I want to know why! Maybe at mach 3 more heat's coming from inside than being absorbed. Concordes were specced with Anti-flash White (high reflectivity as used by US and UK nuclear bombers), and the main reason I remember is there was some publicity when France painted one Pepsi blue (not wings) for a sponsorship. It had to have speed restrictions. Wikipedia has a little more (not much), but says the white finish reduced the skin temperature by 6 to 11 degrees Celsius. https://en.wikipedia.org/wiki/Concorde https://en.wikipedia.org/wiki/Concorde

msandford 10y ago
The sun adds 1000 watts per square meter, and black body radiation is the fourth power of temperature difference. If you're heating the skin say 5000 watts per square meter due to friction or compression, then the 1000 watts from the sun isn't bad. But if it's only say 500 watts, well, then the sun dominates. They operated at different speeds and altitudes so it's not entirely surprising to me that they had different strategies.

hga 10y ago

Note that they were using titanium, and while I'm not sure what the fuel cells were made of, until they heated up it leaked quite a bit. One of the first orders of business after takeoff was getting a refuel, which included changing the type of fuel, see e.g. http://iliketowastemytime.com/facts-you-didnt-know-about-sr71-blackbird http://iliketowastemytime.com/facts-you-didnt-know-about-sr7...