DR400 power setting
The first thing is that the RPM required for % power setting changes with density altitude and so each attitude will have a different RPM for a fixed power setting.
For all practical application you can use pressure altitude unless the temperature is extremely away from ISA.
I plotted a graph with RPM on one axis and pressure altitude 1013 mb on the other with the 60 & 75 % lines as these settings are tabulated in the DR400 manual and are a straight line between zero and the attitude at which the engine reaches max RPM for the given power setting.
The graph gives a quick and accurate RPM setting for % power that is close enough given the relatively narrow tempriture band the DR400 is likely to fly in and the accuracy of the RPM gauge. Ofcouse you must referance your altitude to 1013 as all the numbers are based on ISA and the engine leaned as you increase altitude.
Last edited by A and C; 13th Sep 2012 at 20:18.