[logician2u]

As I recall, the usual claim for the SR-71's speed in the popular press (e.g., Popular Science, Popular Mechanics, Good Housekeeping) was Mach 3+, which could only be achieved at altitude, in the neighborhood of 80,000 ft.

Habu pilots were fitted out almost as astronauts. Not much oxygen at that altitude.

[Texas Fossil]

OK, I did the uneducated estimate. I had previously heard it was capable of Mach 3+ (heard significantly higher)

But the basic math I found did not indicate that.

Thank you for the explanation.