Originally Posted by
JohnBurke
It's absolutely not a "red herring," and your assertion is supported by no documentation. In fact, it's not supported by your link to ANA, either.
With respect John it is!
Page 149 of naval aviators, figure 2.19:,
Apologies for the poor pic you can download the pdf here
https://www.faa.gov/regulations_poli.../00-80t-80.pdf it's page 167 on the pdf or pg 149 on the original
In this diagram the cut off point is a pitch of about 20 degrees. The 15 degrees that I cited in my original post is from a scientific paper from NACA from the 1930s.
The diagram clears shows a course pitch prop at 30 degrees wind milling with about half the drag coefficient of the same 30 degree pitch prop stationary... (30degrees is about full course on bonanza for example)
In my original post I was clear to state that a wind milling prop in fine pitch (e.g. <15 degrees), such you might find a multi-engine aircraft will provide substantially more drag than a stationary one.
The fine pitch setting on turbo props are typically very low blade angles, from the diagram I cited 5 degrees will produce a drag coefficient for a wind milling prop of about 3 times higher for the same stationary prop.
To be absolutely clear 'a fine pitch wind milling prop' with produce significantly higher drag than the same fine pitch prop when stationary, that is not the case for course pitch prop.