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> People thought that mirrored surfaces might just reflect the beam. It turned out that reflective surfaces are actually more vulnerable. Does anyone know why

> People thought that mirrored surfaces might just reflect the beam. It turned out that reflective surfaces are actually more vulnerable. Does anyone know why this is the case? Do mirrored surfaces trigger some sort of internal reflection which ends up absorbing more energy?

barbegal 3y ago
This sounds like completely made up rubbish to me. Reflective surfaces definitely absorb less heat. Mirrors may however be impractical and may not reflect enough to make the missile immune.
- logophobia 3y ago
  Or have a lower melting point, making it more practical to use some sort of heat-resistant armoring? Might be pretty difficult to make something that both reflects light and is heat-resistant, no mirror reflects everything.
Panzer04 3y ago
I think the usual issue is a mirrored surface is not robust enough to absorb extreme levels of energy for very long before it becomes a poor mirror. I expect the counter will be more along the lines of having sufficient ablating material to block the laser - a small amount of extra armour probably has an outsize affect on survivability.
gateorade 3y ago
Just spitballing here but it might have to do with the fact that materials that absorb light are more heat conductive than materials that are reflective. The SR71 was famously painted black as a mitigation for surface heating issues because the black paint conducted heat away from the areas the were really susceptible to ram-heating. Perhaps reflective surfaces reflect some percentage of the incoming energy away, but thermally conductive surfaces conduct a larger percentage of that energy away and are able to safely sink it into some thermal mass.
- worrycue 3y ago
  Black surfaces are good at absorbing AND radiating heat. I think that’s why the SR-71 was painted black. The amount of heat it got from absorbing the sun’s rays probably paled in comparison to the heat it radiated from all the friction as it flew.
  - George83728 3y ago
    From what I understand, the SR-71's black paint did radiate thermal energy, but also made the plane harder to see in visible light at night, and on radar. It was a RAM coating impregnated with iron to reduce the radar cross section. The characteristic chines along the edge of the fuselage were also meant to reduce the radar cross section.

barbegal 3y ago

This sounds like completely made up rubbish to me. Reflective surfaces definitely absorb less heat. Mirrors may however be impractical and may not reflect enough to make the missile immune.

logophobia 3y ago
Or have a lower melting point, making it more practical to use some sort of heat-resistant armoring? Might be pretty difficult to make something that both reflects light and is heat-resistant, no mirror reflects everything.

Panzer04 3y ago

I think the usual issue is a mirrored surface is not robust enough to absorb extreme levels of energy for very long before it becomes a poor mirror. I expect the counter will be more along the lines of having sufficient ablating material to block the laser - a small amount of extra armour probably has an outsize affect on survivability.

gateorade 3y ago

Just spitballing here but it might have to do with the fact that materials that absorb light are more heat conductive than materials that are reflective. The SR71 was famously painted black as a mitigation for surface heating issues because the black paint conducted heat away from the areas the were really susceptible to ram-heating. Perhaps reflective surfaces reflect some percentage of the incoming energy away, but thermally conductive surfaces conduct a larger percentage of that energy away and are able to safely sink it into some thermal mass.

worrycue 3y ago
Black surfaces are good at absorbing AND radiating heat. I think that’s why the SR-71 was painted black. The amount of heat it got from absorbing the sun’s rays probably paled in comparison to the heat it radiated from all the friction as it flew.
- George83728 3y ago
  From what I understand, the SR-71's black paint did radiate thermal energy, but also made the plane harder to see in visible light at night, and on radar. It was a RAM coating impregnated with iron to reduce the radar cross section. The characteristic chines along the edge of the fuselage were also meant to reduce the radar cross section.