I went out for a run tonight and the mind was wandering:

Why did the SR-71 need ¾ of Arizona to make a 90º turn?

If the aircraft is traveling at M=3.0, that's roughly 30 miles a minute. A standard-rate 90º turn should take 30 seconds, or about 15 miles. 2-pi-r is the circumference of a circle, so a standard-rate turn at Mach 3 should be roughly a 5 nm circle, not 300 nm.

Something don't compute, and its probably that the SR-71 doesn't do standard-rate...