>> works fine, however, I notice some differences in the numbers reported >> by the heading and track properties. > >Are you sure that the Digitrack actually knows the roll angle of the airplane? >
I am not sure I have the technical background to understand how the Digitrak actually works. It does not use a turn coordinator as a source of roll information. There is an explanation on the website http://www.trutrakflightsystems.com/overview.html which may be new, I do not remember having it when I made the model for MSFS. In the FG generic autopilot, the second stage of the heading bug hold, inputs /orientation/roll-deg into the controller and uses the target roll as the reference. I copied this to get it working. I looked at the KAP140, but it depends on the turn indicator for input to the wing leveler (roll mode). The Digitrak docs clearly state that it does not employ a turn coordinator, so I cannot take this approach. The overview claims it can sense motion about the three axes, apparently through the directional gyro. I assume it uses that to obtain roll angle. The orientation/roll-angle would be a good place to start, being closest to getting the roll information from the digital gyro. Is it possible to use the directional gyro as a source? It seems that I would need to create my own gyro model to do this. The DG/heading indicator only outputs heading. I can only assume from the documents (the PDF manual particularly) that the gyro is periodically corrected for drift using the magnetometer or the GPS. I have not decided how to simulate this. >Heading and track are _not_ the same thing. Heading is the direction that the >nose of the aircraft is pointing. Track is the direction that the aircraft is You're right. I forgot about wind effects. I have studied this in instructional texts on navigation, but I have become lazy flying PC flight sims by GPS route most of the time. Thanks for clearing that up, Steve _______________________________________________ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
