Best Prop Tip Speed?

Having friends with RV's (mostly 8's), the discussion comes up about propeller design, and the efficiency in certain rpm settings.

A former prop engineer for a major company has stated that they always designed the props for best efficiency in cruise at 750 fpm tip speed. This would be close to Mach .65.

What is your experience in the RV world with various propellers? Is the .65 tip speed pure BS, or is it a real world number for most efficient cruise?

Yes, there are many factors involved, but just trying to simplify the subject so I can wrap my brain around it!

Contact Craig Catto, he will know.

I would think the best tip speed is determined by the shape of the tip, design of the airfoil at the tip, speed of the aircraft, engine torque, tip speed, phase of flight (climb vs. cruise), etc.

N941WR said:

Contact Craig Catto, he will know.

I would think the best tip speed is determined by the shape of the tip, design of the airfoil at the tip, speed of the aircraft, engine torque, tip speed, phase of flight (climb vs. cruise), etc.

Click to expand...

Just sent an email.
Thanks!