I'd like to suggest a couple of changes to the YASim piston-engine model, keeping in mind Andy's past caveats that it is very simplistic.
The most important one is idle RPM. Currently, the YASim c172 idles at about 1,350 RPM. From what I've found, recommended RPM for taxiing a C172 is only about 900 RPM, and some checklists I've see state that the engine should be idling at over 575 RPM, so I'd guess that 600-750 RPM is probably the right range. The second one has to do with static RPM. Under "Propeller Limits", the C172 TCDS lists a maximum static RPM at full throttle of 2,065-2,165. That's well under the maximum 2,400 RPM for a C172R in motion. Currently, the YASim C172 prop goes right up past 2,400 RPM even when the plane is not moving. It would be possible to get these numbers for the C172 by tweaking the math in PistonEngine.cpp, but then another aircraft might not work. It would be more in the spirit of YASim simply to provide the numbers in the config file and interpolate. Where right now, the config file has <propeller radius="1.0" cruise-speed="86" cruise-rpm="2200" cruise-alt="10000" cruise-power="99" takeoff-power="160" takeoff-rpm="2500" eng-power="160" eng-rpm="2500" x="-.6" y="0" z="0" mass="400" moment="8"> we could have something along the lines of (with an unsubstantiated guess for idle and static power) <propeller radius="1.0" idle-rpm="750" idle-power="45" static-rpm="2100" static-power="145" cruise-speed="86" cruise-rpm="2200" cruise-alt="10000" cruise-power="99" takeoff-power="160" takeoff-rpm="2500" eng-power="160" eng-rpm="2500" x="-.6" y="0" z="0" mass="400" moment="8"> YASim could interpolate between static RPM/power and takeoff RPM/power to find the effect of velocity, and between idle RPM/power and static RPM/power to find the effect of the throttle. The engine model would work much more realistically with only a little more work. Comments? All the best, David -- David Megginson [EMAIL PROTECTED] _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel