Expert: Paul Soderman - 12/16/2008

Question
Dear Mr. Soderman,
    I have s quick question about propeller pitch and how it affects performance and efficiency.  Basically, does a lower angle equal more RPM or does a higher angle equal more RPM?  Thanks for your time!

Answer
On most aircraft pitch and rpm are independent variables, so I don't quite understand your question.  Do you mean - how can I recover the same thrust if pitch is reduced.  If so, the answer is to increase rpm unless you are reaching a limit.  Do you mean - what happens if I reduce the pitch on a constant HP engine. If so, the rpm will go up because there is less load on the engine.  Check the following website on propeller performance:

http://www.epi-eng.com/propeller_technology/selecting_a_propeller.htm

or write back with clarification.
Paul