Spitfire Mk IIa performance tests - Patch 1.07.18301

[klem]

Originally Posted by Crumpp

At 992mb at 19C, the density altitude at sea level is 1194 feet.

If the atmosphere is correct, then standing at sea level is the same as being at 1200 feet altitude on a standard day to the airplane.

Your altimeter is just a barometer and measures pressure. It will only show some 554 feet!!!

All the altimeter sees is pressure while the aircraft sees density. Test flying is done at pressure altitude and performance calculated according to density altitude.

Set the ALTIMETER to 29.92inHg or 1013Mb. That is your altitude for starting your performance calculations.

Well that would skip the first calculation of Pressure Altitude from indicated altitude and altimeter setting and I might try that but I don't see how that would change the resulting TAS.

I'm not a test pilot, I'm just doing the Maths and it took me a while to get my head around how to do these tests. I did it that way so I could fly at/very near sea level on the altimeter although as bongodriver says I could just project the 0ft value.

I'm not sure what your trying to say other than to collect the readings in a different way that skips one calculation step.

Do you think my results will be incorrect for some reason? See above fornulae drawn from
http://williams.best.vwh.net/avform.htm#Mach
and my Hurricane results
http://forum.1cpublishing.eu/showthread.php?t=33135