Erik Hofman <[EMAIL PROTECTED]> said: > Jon S Berndt wrote: > > On Wed, 6 Aug 2003 17:41:33 -0400 > > David Megginson <[EMAIL PROTECTED]> wrote: > > > >> you are flying fast enough (i.e. a dive). Any suggestions? JSBSim > >> does not handle windmilling properly either. > > > > > > Any suggestions? > > Windmilling is basically a reverse calculation. > > You know how fast the aircraft goes at a certain propeller RPM. > Now you want to know the propeller RPM at a certain speed. > > That said, implementing it might prove to be more difficult.
Basically that is how YASim calculates the RPM and a value called "Prop Torque" as well as thrust. In the YASim model, Engine Torque is used to increase the prop rpm as it exceeds the "torque" value of the Propeller. Remember the "torque" value of the Propeller is derived using a thrust formula which uses a well known relationship of rpm, velocity and prop radius (prop pitch is in there as well) and another presumed relationship which represents a torque/thrust ratio. So the way it works (or should work) is if the engine torque is greater than the prop torque the rpm is increase proportionally. The increased rpm in turn goes into the torque calculations again on the next iteration. We would be closer to getting it, if we properly applied drag (and or reduced propthrust when the engine torque falls below the prop "torque" value. I do think the reversing prop thing is probably the result of a bug (see earlier message). Best, Jim _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
