mverlin Posted October 22, 2017 Share Posted October 22, 2017 I'm experiencing repetitive unexpected shifts in compass and GPS headings. The only method I'm using is to set the the HSI and autopilot set to heading. If I try to use the Nav and GPS the aircraft will display frequent unexpected course changes. Any suggestions to deal with this is welcome. Michael Verlin Link to comment Share on other sites More sharing options...
Capt_Flappers Posted October 22, 2017 Share Posted October 22, 2017 which aircraft, which panel, which airport, what weather - bernie p.s. no need to call me Capt folks, Capt Flappers is just a name my wife teases me with because of my flight sim obsession. :o Link to comment Share on other sites More sharing options...
mverlin Posted October 22, 2017 Author Share Posted October 22, 2017 All general aviation, all panels, all weather all airports Link to comment Share on other sites More sharing options...
PhantomTweak Posted October 23, 2017 Share Posted October 23, 2017 Different places in the "world" have different magnetic off sets. Thus, a magnetic heading of 245° in California is different when compared to true North, than in Hawaii, just for example. Also, and along the same lines, the magnetic heading will be totally different, in most of the world, from the GPS heading, which orients to true North. Does this help at all? Pat☺ [sIGPIC][/sIGPIC] Had a thought...then there was the smell of something burning, and sparks, and then a big fire, and then the lights went out! I guess I better not do that again! Sgt, USMC, 10 years proud service, Inactive reserve now :D Link to comment Share on other sites More sharing options...
hovercrafter Posted October 23, 2017 Share Posted October 23, 2017 Try Shift D to sync HSI/GPS and magnetic compass and also check if you have compass drift set to on. Gordon Hmmm It might be just D. Not near the flight sim computer at the moment Link to comment Share on other sites More sharing options...
JerryH Posted October 23, 2017 Share Posted October 23, 2017 If I understand your problem correctly, the heading changes occur when you use NAV mode to hold the aircraft on a VOR radial. There are 10 control variables (called PID feedback controllers) in the autopilot section of the aircraft.cfg file that can be revised to improve this. My own analysis several years ago came up with the following values that work well for me in most cases: nav_proportional_control= 20.0 nav_integrator_control= 0.45 nav_derivative_control= 0.0 nav_integrator_boundary= 0.50 nav_derivative_boundary= 0.0 // gs_proportional_control= 14.0 gs_integrator_control= 0.65 gs_derivative_control= 0.0 gs_integrator_boundary= 0.70 gs_derivative_boundary= 0.0 Give it a try and see what happens. Regards, JerryH Link to comment Share on other sites More sharing options...
mverlin Posted October 24, 2017 Author Share Posted October 24, 2017 Thank you for all of your kind assistance. I've tried it with some improvement. The real puzzle its the fact that the compass reading is unstable. With a fixed heading on the autopilot, the compass won't hold the proper heading. It swings wildly at times 180 degrees, sometimes not as large a setting, but if I try to use the GPS, the aircraft will not follow the intending course. The only way I can fly is to keep the autopilot in HDG, and ignore the compass and GPS. I'm at the point where I am considering abandoning flight simulation after almost 18 years. Any help is appreciated. Michael Verlin Link to comment Share on other sites More sharing options...
tgibson_new Posted October 24, 2017 Share Posted October 24, 2017 Perhaps your magdec.bgl file is corrupted? Try replacing it from the FS9 CDs. Is it worse near the poles but OK at the equator? If so, your magdec.bgl file may not be being read correctly? Try moving it from its default location to a new folder (and scenery subfolder) listed at the top of the Scenery Library. Hope this helps, Tom Gibson CalClassic Propliner Page: http://www.calclassic.com Link to comment Share on other sites More sharing options...
JerryH Posted October 24, 2017 Share Posted October 24, 2017 Michael, Now that you've described the compass swings of as much as 180 degrees, it's obvious that my PID controller changes are not the solution. If anyone knows the answer, Tom Gibson will be the one. Don't give up. Regards, JerryH Link to comment Share on other sites More sharing options...
mverlin Posted October 24, 2017 Author Share Posted October 24, 2017 Thank you! I"ll report Back. Michael Link to comment Share on other sites More sharing options...
mverlin Posted October 25, 2017 Author Share Posted October 25, 2017 Thank you, Tom. The problem appears to be resolved. I'll test further. Michael Link to comment Share on other sites More sharing options...
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