The UK has successfully fired a high-power laser weapon against an aerial target for the first time in a trial.
It is hoped that the test will pave the way for a low-cost alternative to missiles to shoot down targets like drones.
The DragonFire weapon is precise enough to hit a £1 coin from a kilometre away, the Ministry of Defence (MoD) says.
I believe they are rated by power output at the emitter. I think your math is correct but these systems aren’t heating water, nor are they heating a kilogram of it. They’re simply trying burn through / melt a few ounces of plastic. The journalist who test fired a 10KW system was able to down a drone in about 15 seconds by slagging its propeller so I have to imagine that a 50KW system would do it even faster, potentially as quick as just a second or two.
That’s why I was saying larger missiles would be more resistant, since they’d have higher thermal conductivity aluminum, and a shorter closing time than 15sec.