Using JavaProp to generate JSBSim propeller coefficients

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This is a tutorial on how to generate thrust and power coefficients for a JSBSim propeller using JavaProp. JavaProp can be obtained from Martin Hepperle's website - follow the instructions at https://www.mh-aerotools.de/airfoils/javaprop.htm -> Step by Step Instructions to install a local copy of JavaProp.

As example "subject" for this tutorial I will use the propeller of the Daher TBM 900.

Step 1 - Gathering data

Find the diameter, spinner diameter, number of blades and the minimum / maximum / feather / reverse pitch settings, governor minimum and maximum RPM for the propeller to be modelled. Barely available, but knowing the real airfoil is of course really really good !

Most of this data is usually available in the POH of the aircraft - but the TCDS (Type Certificate Data Sheet) of the EASA / FAA has proven to be an important data source, too.


Here's the data for the propeller of the TBM 900:

  • Model (name): HC-E5N-3C
  • Number of blades: 5
  • Diameter: 91 in (2.311 m) (I usually pick the larger diameter of the minimum and maximum diameters supplied in the POH)
  • Spinner diameter: can be measured on / estimated from the three-view drawing of the aircraft - not the diameter at the spinner root but the one at the blade station is to be used ! 0.45 m in this case.
  • Pitch settings at the 30 in station:
    • Reverse pitch stop: -9°
    • Low pitch stop: 19.5°
    • High pitch stop: often is not supplied in the POH if the propeller is feathering - it may be supplied in the TCDS of the propeller, but in this case no pitch settings are specified in the TCDS at all - so I took a guess at 30°.
    • Feather pitch stop: 85°
  • Minimum prop governor speed: usually in the POH -> General -> Descriptive data -> Propeller, else in the TCDS or as last resort the lower end of the green range on the propeller tachometer. None of those was available for the TBM 900 though … so I'm guessing at 1500.
  • Maximum prop governor speed: 2000 rpm

Additionally, an airspeed to design the propeller for has to be chosen - should be a low cruise speed. I picked 170 kts

Step 2 - Starting JavaProp and initial setup:

Now start JavaProp - on Linux systems open a terminal window (Ctrl+Alt+T), cdinto the directory containing JavaProp.sh and execute

~/MH-Aerotools/JavaProp$ ./JavaProp.sh

It will (hopefully) show a splash screen for a few moments, then you are shown the main window, with the Design tab open. Enter all your data there (name, number of blades, airspeed

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