Obeisance
I bow to BOAC's response... I was only asking, due to my own inexperience of operating much above M .5 and F/L 25.0. I usually had fans on the wings, which I could see rotate at a reasonable speed and quietly.
My world was flat, when I was acting as a Navigator. I understood that it was said to be an oblate spheroid - but I never really believed them. Why didn't they give me a Globe ?