I’m tuning a supercharged piston engine, but the RPM don’t seem to be under control (lowering the throttle doesn’t lower the RPM) and I’m guessing that the manifold pressure may be too high, so I’d like to use that parameter. But once turned it on, the engine always go to max RPM and will never go down , which is very confusing, please does anyone know how it works.
manifold_pressure_regulator_threshold=0 ; Manifold pressureat which the Manifold pressure regulator
will start having an effect.Default value is 0 [inHg]
manifold_pressure_regulator_tc=1 ;time constant
The supercharge seems work well if I disable the manifold_pressure_regulator.
How is everything running without the supercharger? You didn’t give any information about the propeller setup. That is critical to understanding your RPM issue.
The purpose of a supercharger on an aircraft engine is to allow it to maintain adequate MAP at higher altitudes. Are you seeing this work?
There are many parameters that may not work in the sim or at least it’s not known how they work. If you can find an example of another plane that implements this parameter, you may need to analyze the parameters it is using as a guide.
Thank you for your concern!
The intake pressure for this engine to take off is atmospheric pressure (QFE) + 80mmHg. In ground tests without the supercharger setup, the set RPM and output power for takeoff could not be achieved, and with the addition of surpercharger, the RPM and output power did increase (still needs fine tuning). I haven’t tested the effect of ceiling, but it should have improved. I don’t have the propeller data with me now, I will attach it later.
I have purchased many third party aircraft, but after researching many of them, I have not found any that apply this parameter, and the SDK tool and SDK documentation are in conflict.
You should cure the too high RPM by setting the beta_min so that it can develop the greatest horsepower at the optimal RPM for takeoff. It seems like 14 degrees may be too fine of a pitch and the engine can just spin that up to max.
Then at top airspeed, you can see if you can get close to the beta_max pitch and still be in an appropriate PRM range.
I don’t know much about the supercharger parameters, but certainly the critical_altitude should be set correctly. I think the sim will scale downward from there.
If you get the overall horsepower in a useable range, you may not have to add anything like the MP regulator. Getting the correct MAP to display on the gauges is sort of the last step and more for appearance. After all, we’re not building an actual engine from basic data.
Everyone developing for MSFS right now is an explorer as nobody but the official developers knows very much about how all the code works.
Yes，the beta setting is too low at this given condition，although the data is from the POH of the real aircraft（rather old style).
Thanks for the suggestion，I think I’ve found the way.