Speed graphs for Spitfire and Hurricane

[klem]

Originally Posted by ATAG_Snapper

Thanks for posting this, Camber.

Your SL data for the IIa squares with what I got for both online and offline ie 290 mph IAS +/- 2 mph. Where my data began to diverge (offline vs online) is when I climbed to 5,000 feet and 10,000 feet. The online Spit IIa begins to seriously decline in IAS while the offline Spit IIa holds a fairly steady IAS right up to 10,000 feet (and possibly higher -- did not test beyond 10K).

I can't fathom why the two flight models for the two same aircraft should be so different at emergency combat settings ie. 2800 at full overboost. (The needle goes off scale on the boost gauge, so I can't tell if it's +9 lbs or +12 lbs -- or something else for that matter).

I haven't used the no-cockpit gauges but why they woulld read differently is a real worry, surely these are the same gauges or are the gauges in the cockpit set in the 3D model whilst the no cockpit gauges are 'made' separately. In that case either the gauge plates could be calibrated differently or perhaps the needle rotation formulae are different.

Regarding the on line versus offline difference it could be that different atmospheric conditions are modelled, e.g. perhaps one is a 'standard day' and the other not or perhaps both are not and are different from eachother. Then again, the test environment used by 1C could be different from both.

http://stoenworks.com/Tutorials/Unde...0airspeed.html
That standard is:
1. at sea level
2. standard day (temperature, humidity)
3. a barometric setting of 29.92 inches of pressure

If any of these criteria are off then the indicated airspeed will be different than the actual airspeed of the aircraft.

http://www.elsevierdirect.com/compan...-d/default.htm
IAS = 'indicated airspeed'- this is the speed displayed on the aircraft instruments. As such it is a function of height (static pressure) and forward momentum (dynamic pressure). The value displayed on the instrument will be affected by local atmospheric conditions and by errors from the installation of the sensors on the aircraft.

I've added the 1940 documented data from spitfireperformance.com charts to your jpg so we can see how all the IAS's are off if its supposed to be a standard day.

However, note that the IAS's given for Spitfire IIa in the spitfireperformance chart we have been referring to is 'raw' so I have deducted the Positional Error Compensation and the Comp. figutres to give the true IAS's. I suspect this is what os modelled in CoD, I doubt if they modelled in a Positional Error or Comp. error.