Vivian Meazza wrote: > However (and there's always a however), I can't land the > thing. Closing the throttle and pulling back the propeller pitch > control doesn't reduce the power enough. I reasoned that there was too > much boost with the throttle closed, (currently set at 10%, > AFAICS). 10% of the supercharger output at sea level before the > wastegate is a big number
Yeah, that's a good point. The idle tuning of the engine was done before turbocharging was added, and doesn't really map well to the new regime. As a near-term workaround, you can always pull the mixture way back to reduce power to near-zero. I'm wary of adding a magic number to the configuration files for this, though. I wonder if there's a saner way of calculating an appropriate idle power dynamically from the input values... A related issue that stands to be fixed is that the current code doesn't really model a gear-driven supercharger properly. With a centrifugal compressor like this, the output pressure gain is a direct funcition of RPM. The existing code tries to model an exhaust-driven turbo charger by simply multiplying the input MP by the turbo-mul factor, which isn't the same thing. The behavior will match at maximum power output, but be off in the middle and at the low end. > One other 'however': the property mp-inhg seems to be bound to the > supercharger output before the wastegate is applied. Really? PistonEngine.cpp:112 looks like it is setting the current MP based on the turbo output. Maybe there's a different bug somewhere (units conversion, maybe?) Andy _______________________________________________ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
