ITT simulation

Can we have the formula that is used to calculate a turbine’s ITT? The five
parametres provided currently are:

  • itt_peak_temperature
  • itt_tc
  • itt_tuning_constant
  • fuel_flow_max_itt_factor
  • fuel_flow_min_itt_factor

The only ones that seem to have a somewhat clear function are itt_tc and
itt_tuning constant. However, after running tests with t least 60 different
combinations, I was unable to get the ITT tuned to their RL parametres. When
plotting the charts for my results, it looks as if the ITT follows specific
ratios for low idle, high idle and max power, with itt_peak_temperature just
scaling those higher or lower. fuel_flow_max/min_itt_factor seemed to be what
I need to fine- tune my ITT readouts, but they don’t seem to have an effect.

Hello, We’re currently upgrading the documentation on ITT so here’s some
details that I can give, even though it’s not live yet:

Hope the screenshot is clear
enough for you to read, the formulas are a bit small… And I also hope it

I don’t know anything about Turboprops, but, is fuel flow max and min really
the same for all Turboprops? Are those variables eventually going to get
exposed and be modifiable? Can authors work around that?

No… they aren’t the same for each type of engine…

SonantAlpaca I would like to add a suggestion:
expose the FuelFlowITTMax and FuelFlowITTMin parameters for turboprops. The
current range of temperatures is fixed and leads to unrealistic ITT
temperatures, unless the engine’s max fuel flow is artificially lowered to an
unrealistic level. For example, some reference values from the Kodiak (Sea
level, ICAO standard day): State | ITT real | ITT sim
(settings #1)
| I ** TT sim (settings #2) **
Minimum operational ITT | 400 | Below limit | OK ****
Low idle, feathered prop | 470 | 465 | 585
Low idle, unfeathered prop | 420 | 332 | 410
High idle | 470 | 442 | 530
Climb max | 790 | 794 | 912
You can also watch an engine startup of this aircraft (PT6 engine) in this
video at 21 seconds: Kodiak startup
Below you can see
a chart that shows the distribution of ITT for different settings in the
engines.cfg file. As you can observe, the spread between minimum and maximum
values is specific and we cannot raise the bottom of the threshold without
increasing the top temperatures.
I could also suggest a StarterPeakITTFactor parameter that will set the Peak
ITT the engine can achieve during startup. You will notice in videos (Kodiak)
that the PT6-34 will be at 420oC low idle, but during startup it can reach
600-700 before settling. It won’t get us into hot starts,