PROPELLER RPM LIMITER ANALYSIS

 

This utility can be opened from the Engines debug window, and was developed to make tuning the PID controllers for both propeller RPM limiter types easier, clearer, and more effective (see the Note On Propeller RPM Limiter for more information). Normally, adjusting PID controllers is difficult when done "blind" as it requires guessing the right coefficients and repeatedly checking results without direct feedback on the effect of each term on the system. However, with the real-time charts provided by this tool, you can observe the PID controller signals - and the limited parameters - as they change directly in the simulation. This makes it possible to evaluate the controller response more clearly and adjust the tuning with a higher accuracy.

 

Once you have this window open, you will be able to select the engine to view (if there are multiple) from the top:

 

 

Under the engine selection, you then have three expandable sections containing information and setup data.

 

 

CFG Settings

This section provides reference information about the selected propeller RPM limiter settings, as well as additional parameters that affect its behavior. The amount and type of displayed information automatically adapt to the current settings.

 

 

Curves Legend + Live Data

This section provides a legend for the curve colors on the charts and displays the real-time numeric values of the current parameters. The amount and type of displayed information automatically adapt to the current conditions.

 

 

Charts Settings

In this section, the aircraft maker can set a custom axis scale for the charts. The utility will then automatically adjust this scale for optimal chart display.

 

 

 

Charts

The Propeller RPM Limiter Analysis window will present you with the following two charts:

• Propeller RPM
• Propeller Pitch Angle

 

 

And if the aircraft has the fuel flow governor setup, then you will have a third chart:

• Engine Corrected Fuel Flow (lbs per hour)

 

 

Note that if only the fuel flow governor is initialized (without the prop pitch governor), the "Propeller Pitch Angle" chart will still be displayed, since turboprop engines assume the use of a constant-speed propeller, and the propeller pitch angle is an important parameter for evaluating the overall system behavior.