I seem to sort of remember that Vmca decreases with altitude whilst the indicated stall speed stays the same.
This might explain why I have uncomfortable memories of demonstrating Vmca in a Twin Catastrophy in the Johannesburg GFA one hot summer day.
When the stall speed and Vmca meet or when the aicraft stalls before reaching Vmca things can become interesting in a mild sort of way?
This stimulation of interest becomes exceptionally enthralling if the aircraft in question has tip tanks!
