How about the fastest plane, the SR-71? Does it have this corner?
The fastest man in the world has been my FO here a few times. I'm glad to have the chance to be the non-flying pilot for him on alternating legs. He was an F-4 Instructor Pilot, then flew the SR-71. He finished his Air Force career on the corporate-style G-III at Andrews AFB.
And E. is humble, soft-spoken and religious, definitely not above speaking with other pilots, no matter what their background or present aircraft. This can not be said for some pilots who "streak' around in the DC-10 or 747 (many are too self-impressed with their paychecks). I can ask E. about the corner, but my impressions are that the SR was limited more by temperature, controlling the c.g. with fuel transfer, and inlet airflow control. Even 65,000' was nowhere near the max altitude.
Pardon the comments which are unrelated to the "corner", but the irony of such a pilot's humility is never lost on me.