PPRuNe Forums - POH Perfomance Based on?

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“A sum of 48 equals 75% power (such as 24" MAP and 2400 rpm), each reduction of 3 is a reduction of 10% power, so 45 would be 65% and 42 would be 55%.”

So 24” at 5000 rpm on my machine would = 165%, nice!!!:E

I have the benefit of up to date instrumentation and tend to set power based on fuel flow at a set RPM. I usually go for 4900 rpm at 18.5lph (CS prop) at around 4000 ft.

Rod1

Thanks for help.

Just a question for Big Pistons Forever.... How do you deduce from the tables that above 7k the power falls below 75% from charts? I doubt I'll get that high any time soon from weather here.... But just out of interest...

So, for my flight.... Figure pressure alt, go to corresponding temp. and based on what speed or fuel burn I want, take that RPM and lean for it in flight and I'll end up with that %BHP... Correct?

Quote:

Originally Posted by Private_flyer (Post 5830998)

Thanks for help.

Just a question for Big Pistons Forever.... How do you deduce from the tables that above 7k the power falls below 75% from charts? I doubt I'll get that high any time soon from weather here.... But just out of interest...

For Pipers go to the "engine performance" chart. The top of the 75% power line equals the maximum altitude it is available. For Cessna's go to the "range" chart" . The point the 75% power line kinks to the right is the maiximum altitude 75% power is available

So, for my flight.... Figure pressure alt, go to corresponding temp. and based on what speed or fuel burn I want, take that RPM and lean for it in flight and I'll end up with that %BHP... Correct? Correct

I have embedded the answers to your questions in red

Thanks for that! Has it cleared up for me! :ok: