Sorry to damp the enthusiam about the high speeds capabilities of the ME262.
All of u are true, the ME262 did reach 590mph in dive or even more, but there was a simple prob, at those speeds the plane couldnt be used as gunplatform due to vibrations along the longitutial axis (from nose to tail) that made aiming a futile task.
The effective speed up to which a ME 262 could be used as gunplatfrom was (if i remember right) was around 530 mph, above that speed the vibrations accured and the plane wa off no tactical or operational use.
(will look for the exact numbers at home).
Edit:
good news
tactical limit (up to which plane was able to be used as gunplatfrom) Mach 0.82
adive to the pilots below 8000meters a speed of 960 km/h should not be exceeded, above 8000 m a speed of 900 km/h should no be exceeded
[ 08-14-2001: Message edited by: Naudet ]