Wow
SR-71 altitude record was just over 85,000 feet.
World circumference at that altitude (2*pi*R) is equal to 534,070 feet.
So at that altitude they could circle the world in 101 seconds. (534, 070/5280).
a minute and 1/2 at max record altitude to go around the world. I’m guessing the real challenge is not shooting out of the atmosphere.
Additional math shows at typical geostationary orbit level they cold circle the world in about 6 hours at that speed.
Isn’t the earth 24,000 miles around at the equator or over 131 million feet?
Did you only count the 85,000 feet of altitude, and not all the way to the center of the earth In your equation?