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Author Topic: AIR_70_ITT questions
WarpD
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Post AIR_70_ITT questions
on: May 22, 2012, 11:28

Since I'm picking LM brains... gonna ask about a couple .air file tables that I've never really figured out entirely.

There are entries AIR_61S_OIL_TEMPERATURE, AIR_61S_OIL_PRESSURE, AIR_70_ITT etc... and they all have 3 fields: a 'tuning constant', a max value and a 'time constant'.

Would it be too much to ask how these values are used to calculate the results in the sim? It's been more or less a 'hit/miss' game of trying to set correct values in the 'tuning constant' and 'time constant' to get decent values returned. A better understanding of how the sim actually uses those values would g a long ways to reducing the 'guessing game'.

Ed Wilson
MikeSchroe-
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Lockheed Martin
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Post Re: AIR_70_ITT questions
on: May 22, 2012, 15:30

They have an internal normalized algorithm based on the appropriate parameters (e.g. N, combustion, damage, atmosphere, etc...). The "peak" or "max" value essentially sets the high end "normal" limit. The "tuning constant" is just a scalar on top. It essentially does the same thing as scaling the max value by the same value and leaving it at "1.0". These generally utilize 1st order lags, in which the time constant is that specified in those .air blocks.

WarpD
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Post Re: AIR_70_ITT questions
on: May 22, 2012, 18:11

When you state 1st order lags... would that be something like this: new_value = time_constant * raw_value + (1 - time_constant) * old_value?
MikeSchroe-
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Lockheed Martin
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Post Re: AIR_70_ITT questions
on: May 23, 2012, 11:43

Yes, that looks right.
WarpD
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Post Re: AIR_70_ITT questions
on: May 24, 2012, 21:48

Thank you sir.
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