wuzak
Captain
I think you need to review some combat reports W, & watch a few gun-cam films then,
If the Wingco Flying of the Tempest outfit, R. Beamont, ( & who was also a Hawker test pilot)
put it in his official combat reports, as well as in his memoirs, he's confident about it.
Addit: The mph noted is IAS, per the ASI, & some of those combat reports note
dives 'going off the clock' & ' well past the ASI redline.'
600mph IAS - I call bollocks. Or faulty equipment. Or that is 600mph IAS = 600mph TAS - ie at sea level. Just before the aircraft augured in.
The ASI was in those instances, most likely,faulty. There were similar claims from P-47 pilots which would have had them doing speeds approaching 700mph TAS.
8,000ft would be, in my mind, about the time you would want to be pulling out from a high speed dive, not initiating one.