Today's airplane "black boxes" are mostly solid state, recording critical flight data in semiconductor memory.
But before the days of cheap, durable flash memory, and even before magnetic tape, here's how a flight data recorder worked: By scribing lines in a long sheet of inconel steel foil: A metal hard enough and corrosion-resistant enough to withstand even the most extreme environmental catastrophes: up to 3,000 Gs and up to 1,000 degrees Celsius.
They were a marvel of super-durable, mostly-mechanical engineering.
Bill Hammond, the "Engineer Guy," explains just how that worked in this accessible two-minute video.
And if you want a flight data recorder of your own, you can buy one for about $125 on eBay.
