David M. wrote: > I tried to fix this problem in JSBSim a year or two ago, and I seem to > recall that no one on the flight model list could quite figure out how to > code it back then. I also took a stab at YASim, and failed just as > miserably. Neither model is set up to have the propeller driving > the engine rather than the engine driving the prop. > > The rule of thumb for pilots is that a windmilling propeller creates as much > drag as a disc of the same size, but that's too vague for modelling (plus, > it doesn't handle the partial-windmilling situation). What we need to > figure out is how much drag we get from the propeller turning the > crankshaft, compressing the cylinders, and spinning the accessory drives > (vacuum pump, alternator, etc.).
Curt wrote: > It very well could be a model setup issue at which point it's probably > beyond my ability to debug, but with the JSBSim c310, I took off, climbed > to a comfortable altitude and speed, and chopped the throttle on my right > engine. Then I slowly pitched up to bleed off speed little by little. As > the speed bled off, I held my heading with rudder and kept the > wings level with aileron. > > From the readme: > > Minimum single-engine control speed (Vmca): 75 KIAS > > However, I was able to fly right through this until I got the stall horn, > (about 60 kts?) and all the time, the rudder had plenty of effectiveness to > hold heading. In the real thing (assuming the README is correct) at about > 75 knots the rudder loses enough effectiveness to hold heading against the > one good engine at full throttle and you begin an uncontrollable yaw. This > doesn't happen right now in the JSBSim C310 anyway. As for the -310, I think we may have fixed both the propeller model and the stability issue. If someone wants to try out the C-310 doing the same test that Curt did above, I'd be interested to hear the results. I'll get to it sooner or later, but if someone else wants to grab the aircraft from JSBSim CVS and get the modified FGPropeller.cpp from JSBSim CVS, go ahead. Jon _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
