Kind of an odd question.
The central idea of dive bombing is that by diving steeply you
minimize your motion relative to the ground and are suppose to be able
to aim and deliver more accurately. If you are going straight down at
your target, you can't miss!
The Stuka's trick was that it could stand on its nose long enough to
aim and release WITHOUT building up so much speed that the pilot
didn't black out or the wings snap off during the pull out. That's
what the dive brakes were for. (I remember reading that some Stuka's
were equipped with an auto-recovery mechanism set to initiate pull out
at 1500 ft.)
So, how FAST could it go in a dive? Too fast. A better question is,
how SLOW could it go?
Watanabe's "Stuka, Ju 87" quotes max diving speeds of 279 mph for A-1
and 404 mph for B-1. I'm guessing those are max ALLOWED speeds!
Greg Reynolds, IPMS