Mosquito speed over Bf 109 and Fw-190

[Graham Boak]

I wonder what the pressure error is on a Mosquito under those circumstances? There is clearly no way it could ever have achieved 650 kts True, but at what speed would the ASI have been indicating 480 Kts IAS?

I wonder, but I suspect it is not on record.

[andy bird]

TAS as typed on the report.

Andy

[Graham Boak]

I don't doubt that's what it says, but it isn't possible. No Mosquito could get that close to Mach 1. I don't know its limiting Mach number but it must be around 0.8M or 530 kts True, (580 mph) The reasons why would not have been understood at the time outside of a comparatively small number of specialists, so it wouldn't set any flashing lights going in the minds of the normal squadron pilots or intelligence officers.

480 kts True would have been exciting enough, and a misunderstanding based on that is another possibility, but I suspect a large pressure error due to compressibility is the likeliest cause. There is quite an amazing list of aircraft that supposedly went above Mach 1 around the end of WW2, but it was all due to pressure errors (and a bit of wishful thinking).

NOTE: knots are about 10% above mph. Correction due to Martin Giles.

[MW Giles]

Graham

You are right about the reported speed being excessive, but by going from mph in the original posting to knots you have added 10 % to all the figures, all on your own

Regards

Martin

[Graham Boak]

Working in knots/Mach is a career-long habit I'm afraid and hence difficult to shake off - sorry. I'll add a note to the text in case people don't read on to your's.

This does make the pressure error rather less extreme, about halving it.