I can't answer this at length at the moment, but a couple of months ago I turned off JSBSim turbulence completely because I had some questions about it myself. If you get the FGAtmosphere.cpp file from JSBSim CVS, that should include the newly turned off turbulence.
I hope to revisit that in the near future. I have assembled some reference documents to review as time permits. Jon > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of > dave perry > Sent: Sunday, December 02, 2007 9:45 PM > To: FlightGear developers discussions > Subject: [Flightgear-devel] [Fwd: Re: [Flightgear-users] Seneca II - > couple of user comments] > > I am forwarding an exchange from today's users list to the developers > list because it raises a significant difference between jsbsim and > yasim. These fdms treat turbulence very differently and jsbsim has a > very exaggerated adverse-aileron yaw that makes this difference fatal > for autopilot ILS approaches even in light turbulence. > > -------- Original Message -------- > Subject: Re: [Flightgear-users] Seneca II - couple of user comments > Date: Sun, 02 Dec 2007 19:10:05 -0700 > From: dave perry <[EMAIL PROTECTED]> > Reply-To: FlightGear user discussions > <[EMAIL PROTECTED]> > To: FlightGear user discussions <flightgear- > [EMAIL PROTECTED]> > References: <[EMAIL PROTECTED]> > > > > Laurence Vanek wrote: > > For my money, the Seneca is one of the best done aircraft in FG. > Have > > been flying it a good deal of late. > > > > > Agreed! > > <snip> > > [2] On localizer during an ILS approach the A/P seems unstable > > (increasing roll oscillations) when within ~1 mile of approach end of > > runway. Perhaps this requires tweak of A/P controller constants. On > a > > CAT II or III approach one would still not be able to see the runway > at > > that distance. I usually disable the A/P at DH point. > > > I have commented before about the difference between yasim and jsbsim > when it comes to two autopilot issues. > 1. jsbsim becomes almost uncontrolable with turbulence. Even at 0.1 > or > certainly at 0.2 turbulence, the c172p will not complete an approach > with the kap140. So, make sure you have turbulence at 0. > 2. I spent many many hours tweaking the SenecaII autopilot config > file. Since jsbsim (in my opinion) has a very exagerated adverse > aileron yaw response and most autopilots have aileron but not rudder > roll outputs, this creates the oscillations. That is why I put in the > menu options for the SenecaII a yaw-damper that may help some. It is a > controller that applies rudder to try and keep the ball centered. > > To see the fdm difference, fly the Senecal II and then the pa24-250 > (which has the same autopilot nasal file and very similar autopilot > config file) down the same ILS. The pa24-250 with the Century III > autopilot will be rock solid all the way to the runway center line even > with light to moderate turbulence. The pa24 uses yasim. You can see > the same comparison between the jsbsim c172p and the yasim pa28-161 > which both have the kap140. > > <snip> > > Does anyone know of a jsbsim model with autopilot that will fly an ILS > with no oscillation with even very light turbulence? > > -Dave Perry > > ----------------------------------------------------------------------- > -- > SF.Net email is sponsored by: The Future of Linux Business White Paper > from Novell. From the desktop to the data center, Linux is going > mainstream. Let it simplify your IT future. > http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 > _______________________________________________ > Flightgear-users mailing list > [EMAIL PROTECTED] > https://lists.sourceforge.net/lists/listinfo/flightgear-users > > > > ----------------------------------------------------------------------- > -- > SF.Net email is sponsored by: The Future of Linux Business White Paper > from Novell. From the desktop to the data center, Linux is going > mainstream. Let it simplify your IT future. > http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 > _______________________________________________ > Flightgear-devel mailing list > Flightgear-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/flightgear-devel ------------------------------------------------------------------------- SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
