Getting airspeed correct at altitude in a piston

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1

Hi All

I’ve started further editing of the bonanza’s engine.cfg. When we first looked at it we set the aircraft to have 4 cylinders and tweaked accordingly. Our changes matched the POH but subsequent sim updates have made the aircraft slightly overpowered with slightly less fuel burn than anticipated.

I’ve started looking at editing the engines.cfg to bring it more in line with the POH but can’t seem to get the numbers right. I can get the tas to be correct for low level but when we get up around 6000ft my numbers fall off faster than the POH. Fuel burn is within .5 all the way up to 16000.

At the moment it looks like I can get it right at altitude and wrong down low, or vice versa. Can anyone help? Or know what causes this? I presume it is a setting I have missed or not understood regarding fuel/air mixtures???

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If you fly too fast for a given fuel burn, I would say you’re not draggy enough.

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Will increasing drag not affect the falling off of airspeed at high altitude even more? At the moment I can get the speed right up to about 6000ft but after that if drops off what the POH states.

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You can test your hypothesis about the mixture by enabling the fuel_air_auto_mixture parameter. Your drag problem can be a polar problem, that is a CL vs CD or CD vs AOA problem rather than a too high/too low CD.