POH Power Setting Table Errors
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Be aware that it is not possible to match some of the settings in the POH Power Settings tables for this aircraft... The reason is that with standard ISA weather conditions, which these tables are supposedly based on, you cannot achieve a Manifold Pressure greater than standard ISA without a Turbo Charger! The standard ISA pressure is 24.90 at 5,000 ft., 23.98 at 6,000 ft. and 22.22 at 8,000 ft. The required Manifold Pressure settings shown below clearly exceed these values...
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@RetiredMan93231 said in POH Power Setting Table Errors:
Be aware that it is not possible to match some of the settings in the POH Power Settings tables for this aircraft... The reason is that with standard ISA weather conditions, which these tables are supposedly based on, you cannot achieve a Manifold Pressure greater than standard ISA without a Turbo Charger! The standard ISA pressure is 24.90 at 5,000 ft., 23.98 at 6,000 ft. and 22.22 at 8,000 ft. The required Manifold Pressure settings shown below clearly exceed these values...
That's a good observation. I don't know anything about flight test in order to tell you how they came up with those values in the first place, but ram air pressure would influence manifold pressure. In fact, most modern airplanes in this class have the air filters placed somewhere that would take advantage of ram rise. Probably safe to assume that MSFS doesn't model ram air effects for piston engines, so your point still stands.
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@RetiredMan93231 said in POH Power Setting Table Errors:
Be aware that it is not possible to match some of the settings in the POH Power Settings tables for this aircraft... The reason is that with standard ISA weather conditions, which these tables are supposedly based on, you cannot achieve a Manifold Pressure greater than standard ISA without a Turbo Charger! The standard ISA pressure is 24.90 at 5,000 ft., 23.98 at 6,000 ft. and 22.22 at 8,000 ft. The required Manifold Pressure settings shown below clearly exceed these values...
That's a good observation. I don't know anything about flight test in order to tell you how they came up with those values in the first place, but ram air pressure would influence manifold pressure. In fact, most modern airplanes in this class have the air filters placed somewhere that would take advantage of ram rise. Probably safe to assume that MSFS doesn't model ram air effects for piston engines, so your point still stands.
@C525B said in POH Power Setting Table Errors:
Manifold Pressure greater than standard ISA
Its more accurate to say you can't achieve some of the MP/RPM combinations listed in the table on a standard day. However, on a colder than standard day, you can. I live in New Hampshire in the US and we get a very wide range of weather. In the winter, I fly in weather as cold as -15F (-23.3C) or as hot as 95F (35C) in the summer. In the winter I can generate 75% power at higher altitudes and as such achieve higher TAS in colder weather. That's the purpose of the foot note to correct the MP required based on temperature.
