I promised I would get back with more data on the Hartzell CS 70" prop utilized by 320's. 

 

The pitch limits are set 30" from the center at 12* for fine and 40* for max coarse.  Of course, the 75% position (26.25") is slightly different and I measured that as about 2* more angle. So, wind milling at fine pitch of about 14 degrees puts that point on the curve about where the arrow is located - and above the stationary propeller drag.  If the prop can be pulled to coarse pitch, about 42*, the drag is almost as minimized as in full feather and certainly less drag than when stationary.  Remember I am using the same prop angle condition that Paul used by not including the additional and unknown angle of attack.

 

Just for comparison, the widest blade chord is 6.5" and the chord at the tip is about 5".

 

I see why I get such good prop drag on final at 13" MAP since the RPM is well below the 2500 selected by the pilot and the prop is at the finest pitch setting. 

 

<<<<<<<<<<<

Here is some data from my 320 powered LNC2 with the 70 inch Hartzell prop.  This propeller is the same design as an 84 inch prop, but with 14 inches lopped off (by Hartzell design).  Thus, the blade is very wide.  At cruise pitch (somewhat fine), power reduced to near idle and at best glide (about 107 KIAS for the load as indicated by the AOA device), the descent rate was 1500 to 1600 fpm (107 Kts is 10,836 fpm), a worse case ratio of about 6:1.  At coarse pitch, the rate was reduced to 400-500 fpm and a worse case ratio of about 21:1.  I don't know if I could get the prop to stop for a test, but I think the drag is some where between fine and coarse (the area of the chart curve where beta is less than 22 degrees).

>>>>>>>>