Despite having read elsewhere that the P-51 Mustang could exceed Mach 0.8 I found those comments of an encounter report:
Pilot: Lt.Col. Thomas L. Hayes
date: 28th of may 1944
unit: 364 Fighter Squadron, 357th Fighter Group
time: 14:00 DST
area: NW of Magdeburg, Germany
quote:"(...)Taking up pursuit again, I was able to get on one of the Me-109, which now began to dive (now following details of the kill...) I WENT OUT OF
CONTROLL INDICATING 500 MPH @ 20.000ft. AND SO DID MY WINGMAN"
At 20.000ft altitude, Mach 1.0 is normally encountered with 706.6 mp/h
(699.5 Mp/h with temps. 5 degrees below normal and 713.7 mp/h with temps 5 degrees above normal), so both Mustangs went out of controll at Mach 0.71 instead of the often quoted 0.82 figure.
Altough I also read several accounts of Mustang Pilots swearing they hit 650 mp/h at low altitude, implying Mach 0.85.
Any ideas anyone?
Thanks in advance,