My bad. It would have been more accurate to say MMO (Mach max operating) as opposed to Vmo (velocity max operating). Sometimes they are interchangeable.
EC
No worries. Most of my seat time was in an Aeronca Champ. 😉
I don’t think ‘Mach’ numbers were even in the 1940s manual. Also you probably couldn’t hit Vne in a full ‘power’ vertical dive. 80 HP ya know.