This is actually a good question to pass along to the FlightGear developers list, too. I'll repost any good answers here to the JSBSim list.
> Andreas wrote: > > > I want to use JSBSim to simulate an airplane (no matter which airplane, so > > I use > > the Cessna). > ... > > The problem now is that the simulation time is not the real time, e.g. 20 > > "simulation seconds" are executed in only 1 "real" second (clock time). But > > I > > need the simulation time to be equal (or almost equal) to the real time. I > > guess I can correct it by changing the value of 'dt' (e.g. 'dt=0.0001' > > instead > > of the default 'dt=0.0083333'), but then the autopilot cannot hold the > > altitude > > and always crashes :( > > ... interesting ... > > > Maybe someone can help me. It should not be that difficult, as FlightGear > > already does it (with 't' or 'T' you can change the speed of the time). > > Yes, this would probably be a simple change. It would involve creating a > timing loop in > JSBSim.cpp (for the standalone version), so that the FGFDMExec::Run() method > would be > called at the same rate as the "dt" value - in this case, at 120 Hz (0.008333 > seconds per > "frame"). > > Now that you bring this up, it sounds like a good option to have for the > standalone > version. That is, there could be an option: > > ./jsbsim --script=scripts/c1723.xml --realtime > > or, the script itself could specify "realtime" as an XML directive. > > I see a problem, though, because it is very OS-dependent. A Mac, a PC running > Linux, > Cygwin, Windows, and IRIX, etc. all will do timing differently. Yet, as you > mention, > FlightGear seems to do it OK. > > Any comments from anyone else? > > Jon _______________________________________________ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
