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JSBSim, FADEC and propeller blade pitch

Good sims require good FDMs (the "thing" that makes an aircraft behave like an aircraft).

JSBSim, FADEC and propeller blade pitch

Postby zakharov » Wed Jul 01, 2020 8:14 am

Hello,

I'm currently playing to create a JSBSim FDM for the Diamond-DA42. After the "envelope" created by aeromatic and some tweaks I focus on the propulsion part of the FDM. On DA42, depending on the power setting, the propeller pitch is adjusted such that the required RPM follows a table (found in DA42-NG documentation, page 7-30):
Code: Select all
          <table>
            <independentVar>/controls/engines/engine[0]/throttle</independentVar>
            <tableData>
              0.00   2150
              0.20   1800
              0.92   2100
              1.00   2300
            </tableData>
          </table>
I've written channels for the two engines, which contain each the targeted RPM table depending of power setting above, some switches and a JSBSim PID controller to get the blade pitch angle adapted from the difference of actual and targeted RPM. I can't say it works at the moment, but this is just the really beginning.

Before I continue this way I wonder if JSBSim can handle by itself the RPM depending of blade pitch without I have to determine by myself the torque and all the data that will lead the propeller to run faster or slower depending of the blade pitch. Or maybe someone would show an other and better way to achieve this kind of blade-pitch adjustment :D.

Thanks a lot and best regards

zakh
Callsign: zakh Immat: f-zakh
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Re: JSBSim, FADEC and propeller blade pitch

Postby Octal450 » Wed Jul 01, 2020 4:57 pm

Make sure that you control the trigger properly with your PID as well in order to make it work - I'm not aware of any logic to do this in JSB, but I haven't played with variable pitch props that much.

Kind Regards,
Josh
Skillset: JSBsim Flight Dynamics, Systems, Canvas, Autoflight/Control, Instrumentation, Animations
Aircraft: A320-family, MD-11, MD-80, Contribs in a few others

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