Rule of Thumb - RPM per Inch?

[jevery]

I've forgotten. Isn't one inch of pitch worth 300 - 400 RPM? What should I gain dropping 4" pitch with similar type props?

 

[Silvertip]

Re: Rule of Thumb - RPM per Inch?

150 - 200 revs per inch of pitch is the accepted number but that is highly variable. If you have an engine that is way over propped and you drop pitch you may see much more than that. And that number also assumes you have the same manufacture and same prop series. Two props of the same pitch from two different manufacturers may not show the same performance.