I read somewhere that it started at 80,000 feet and descended to 20,000 feet in 7/8ths of a second!

I want to know what that is in miles per hour. I converted that to 11.363636 miles / 0.875 seconds, then multiply for hours and I get…

46,753 miles per hour!

Is that correct? Did I get the details right? I used a simple calculator, might have rounding errors?

Any links to confirming sources would be appreciated!

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Then I’m trying to find some other stats on manned vs. non-manned speed records within our atmosphere.

“The fastest airplanes in the world – X-15: The X-15 holds the record for the fastest speed ever achieved by a manned, powered aircraft. It reached a top speed of Mach 6.72, or 4,520 miles per hour.”

“The fastest aircraft is NASA’s X3 jet plane, with a top speed of 7,000 mph (11,200 kph).”