Hawk,
totally agree. Mach 0.62 is not likely to be feasible at high flight levels because your EAS would then almost cetainly be below your stall EAS.
My understanding is that as an aircraft climbs, the stall EAS (for a given weight) remains constant but the limiting Mach Number (expressed in EAS terms) reduces. Therefore if you climb high enough there is an EAS which is simultaneously the limiting Mach Number and the stall speed for a given height/weight combination i.e. the Vonly as posted previously (I like that by the way, Vonly is a good term!)
It appears, therefore, that Vmd ceases to be an option above a certain height (for subsonic aircraft at least) because it would be below the stall speed, and Vmr may ultimately be unobtainable due to the limiting Mach Number and wave drag. I guess that in that case, for max range you need to fly just below Mcrit to avoid wave drag, and for endurance you just fly as slow as you can with a safe margin above the stall.
Anyone care to comment?
WF