Resend after getting bounced earlier ... On Tue, 2003-01-07 at 14:39, David Megginson wrote: > Curtis L. Olson writes: > > > - respect runtime property changes (i.e. new altitude or location) > > > > I would respectfully suggest that this one not be implimented or at > > least be put at a low priority. We tried to do this in JSBsim and it > > can really get messy. > > The problem was that the startup trimming routine and the properties > always ended up arm-wrestling. In principle, this should be very > easy: > > 1. Before each iteration, copy all state variables in from the > bus/property tree. > > 2. After each iteration, copy all state variables back out to the > bus/property tree. > > YASim already does #2; it simply needs to add #1. > > JSBSim retrims automatically when certain values are changed outside > the FDM unless certain properties are set, etc. -- it's all fairly > confusing. > > Over all, I think it would be better if none of the FDMs trimmed > automatically. FlightGear, which provides the primary user interface, > is in a much better position to know when trimming is required; for > example, you do want to trim when an altitude and speed are selected > on the command line, but you do not want to trim when a flight is > being restored from a save file. If the FDMs simply retrim for steady > state when requested, we can make sure the request is issued when > needed. That should clean up the JSBSim/FlightGear interface code a > bit as well. > > Tony: what do you think?
Aside from restoring from a saved state, when do you need the trimming routine to step aside? It seems to me you'd want it the rest of the time. > > > I think it would be much cleaner to force a reset to a new location > > each time we warp to a new location. This allows us to delete the FDM > > instance and create a new one so it can be freshly inited and trimmed > > for the new conditions. Otherwise, it's really hard not to carry over > > some state from the previous location which can cause obscenely large > > forces and other wierdness. > > The problem is that when we restore a saved flight or > start a premade scenario, You realize that this situation is exactly what the trimming routine is good for, do you not? In what way does it create a problem? > we'll get bumps (etc.) from the trimming routine, when the > saved state was already (presumably) steady. It must not have been ... of course, it's highly unlikely that any human can trim an aircraft as precisely as the trimming routine. > I think we're pretty > close -- you want to force a reset, and I want to be able to request a > retrim. > > > All the best, > > > David -- Tony Peden <[EMAIL PROTECTED]> _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
