Prop tip speed calculator

[Admin]

My dealer for Composiclean products in the States told me about a calculator for figuring propeller tip speed for max performance. Pretty

 

cool.. http://www.pponk.com/HTML%20PAGES/propcalc.html

 

 

[Smokey]

This calculator takes prop dia, rpm and temp then returns the tip speed in mach (and mph) and then goes on to state "To produce maximum thrust at full power your tip speed should fall between .88 and .92 mach."

 

They appear to have based this assertion on their own static thrust experiments (http://www.pponk.com/HTML%20PAGES/propellers.html) and are calculating the speed purely on flat plane rotation with no allowance for advance. (Test of 7 propellors in one day.)

 

No mention is made of pitch although reading between the lines they were varying the pitch to achieve max thrust at a particular rpm.

 

The calculator does not make any mention of the fact that it applies to a static test (my assumption), hence by ommission implies it is applicable to a dynamic situation. The calculator also works out tip speed based on flat plane rotation with no allowance for advance.

 

I would seem to me that extrapolating a static test to a dynamic situation and implying that a flat plane tip speed optimum also applies in a dynamic situation is stretching things a little far.

 

Does anyone know of any, more detailed, information on optimal tip speed ?