On 20 Aug 2004 07:04:30 -0700, (Daniel)
wrote:

Hartman & Biermann investigated & tested such props back in the
1930's. While they do indeed gain a bit in peak thrust, they lose
quite a bit of thrust at take-off. Minor thrust improvements at
cruise have relatively negligible benefits and major losses in thrust
at take-off have significant negative effects, hence such planforms
were shelved for almost all applications. Reference NACA Technical
Report 643.

I'm not positive, because I don't have the article in front of me as I
write this, I'll check tonight, but I don't think this prop lost any
takeoff or climb performance.

As to the planform being like those tested by Hartman and Biermann, I
have not seen their planforms so I can't comment. If you look at the
prop in the picture cited he

http://www.contactmagazine.com/Issue77/PaulsProp.JPG

Perhaps you can tell me if they are in fact similar.

Corky Scott