100% prop pitch is equivalent to 12.30 on the prop pitch instrument (pitchometer?). 12.00 is 90%. When you land with prop on auto with a normal low power setting of 1,500 to 1,800 rpm the pitchometer settles at 12.00 and stays there throughout the whole landing sequence. So you land with prop pitch at 90%.
The 109G manual says, if I remember right, land with prop on automatic or if you must use manual control (eg if the automatic control is non fuctional) set the prop to 11.30, which is between 80 and 85%.
(Anyone at all interested in this aeroplane should download a copy of the translation from one of the 109 sites.)
I have tried manual at 100% and do not like it - it needs much higher engine rpms to maintain a given glide path and is less responsive to throttle changes to adjust rate of descent. I suppose that is because the prop is not at peak efficiency. Also not needed to slow down when all you have to do is trim the a/c to the right AoA.
Manual at 80% is better than 100% - more control - but auto is optimum for me, and the manufacturers. Clever fellows, these germans.
BTW the time when manual prop is recommended in the manual is when you are adjusting boost and rpm to achieve the recommended cruise settings, but since the autosettings do a pretty good job of this anyway at normal IL2 heights I do not bother.
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08-05-2008, 05:35 AM
Hybrid Mode
