Spitfire Mk IIa performance tests - Patch 1.07.18301

[klem]

Originally Posted by ACE-OF-ACES

I think so.. In that I found and error in your Density Altitude calculation

See the following REVIEW of your Java code.
...............................................
Where:
T_std = T_o - Alt_ind × TLR = Standard Temperature in Kelvin
T_o = ISA Standard Temperature @ SL
TLR = ISA Standard Temperature Lapse Rate
OAT = Outside Temperature in Kelvin[/code]

Now lets review your Java implementation of Williams formulas

Here is the Java code you want to use

Density_Alt = Pressure_Alt + (T_std/TLR) * (1 - Math.Pow((T_std / Z_AmbientAirTemperature),0.2349690));

OK I get the Constant versus T_std/TLR error, I made the mistake of taking it directly from his example

Where:
T_std = 288.15 - Alt_ind × TLR
TLR = 0.0065

OK

If you plan on doing any testing above 36Kft than you will want to adjust TLR as follows

if ( height < tropopause ) then
   TLR = 6.49(°C/1,000m) = 1.98(°C/1,000ft) = 3.56(°F)/1,000ft
else
   TLR = -56.5(°C) = 216.65(°K)

Where:
tropopause starts at 11.0km (36089.24ft) and ends at 20km (65,616.78ft)

I don't but I might build that into the code in case anyone else wants to use it.

Also not sure if you can use Z_AmbientAirTemperature directly in that it is not realitve to I_Altitude.. And as you know small temp differences can have a big effect on Density Altitude calculations, so hopefully these are small differences. Might be better of using the ISA Standard Temp formulas adjusted for temp.

The Z_AmbeintAirTemperature appears to be the OAT at the altitude, it decreases with alt at around 0.0021C/ft

Hope this helps! S!

It does, thanks. Also learning from Robo that the BCO doesn't work unless I wiggle the throttle.