On Tue, 2002-02-26 at 14:54, Andy Ross wrote: > Tony Peden wrote: > > OK, JSBSim now reports control surface positions. I set up the > > following properties: > > > > /surface-positions/elevator-pos-deg > > /surface-positions/left-aileron-pos-deg > > /surface-positions/right-aileron-pos-deg > > /surface-positions/rudder-pos-deg > > /surface-positions/flap-pos-deg > > > > I believe the sign conventions are the same as those used by FGControls, > > but holler if they need to be different. >
I was afraid this approach would bite you. > Hrm... I'm not liking the idea of specifying explicit, absolute angles > as the interface here. First off is the problem of configuration -- > what are the appropriate angles? Whatever is appropriate for the particular aircraft you are modeling. > If we put them in the property > interface, then both the FDMs and the model need to know. Well, in the case of JSBSim and the primary flight controls, we need to know anyway. Stability derivatives are derived based on the angular deflection of the surface. > If we use > abstract coordinates, only the model cares. > > Also, this ties us to a particular style of surface design. Only if the 3D model needs translation information. > Not all > control surfaces simply rotate around a joint. In particular, flaps, > slats, spoilers and speedbrakes often have a translational component. > Should the FDM worry about this too? Yes, the c172 uses Fowler type flaps. > Even among small planes, this > doesn't always hold. Piper cherokees have a tailplane with a hinge in > the middle. The whole assembly rotates, and the middle hinge rotates > about a different angle for any given deflection. > > And then there's the fact that YASim cares nothing at all about these > numbers. Adding them to the FDM would do nothing but add complexity; > there is nothing useful I can do with them. > > Remind me what the specific complaints were about the use of abstract, > range-bounded numbers for control surface positions? David had his model set up to use the angular rotations and that is, as it happens, easy for JSBSim to provide. So no particular complaints that I know of. > > Andy > > -- > Andrew J. Ross NextBus Information Systems > Senior Software Engineer Emeryville, CA > [EMAIL PROTECTED] http://www.nextbus.com > "Men go crazy in conflagrations. They only get better one by one." > - Sting (misquoted) > > > _______________________________________________ > Flightgear-devel mailing list > [EMAIL PROTECTED] > http://mail.flightgear.org/mailman/listinfo/flightgear-devel > -- Tony Peden [EMAIL PROTECTED] We all know Linux is great ... it does infinite loops in 5 seconds. -- attributed to Linus Torvalds _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
