When the propeller spins backwards in the demo reel, confidence that the engineers will make an airworthy aircraft is instantly flushed down the toilet.

On Monday, August 17, 2020 at 1:39:31 PM UTC-7, Eric Greenwell wrote:
Per Carlin wrote on 8/17/2020 12:58 PM:
The Main factors for power from a propeller are diameter, pitch and rpm, not the number of blades.

An increase from 2 to 3 blades gives at best about 10-15% more drag if the remaining is constant. However the efficiency of the propeller drops by 5-10% and this is a major drawback in electrical propulsion system for gliders.

I think something is missing in your explanation: for example, 3, 4 and 5 blades
are common on airplanes, and wind turbines routinely use 3 blades. My
understanding is tip speed is the ultimate limit on the power a propeller can
absorb, so adding a 3rd should 50% more power capability.

Take a look at this bad boy - Five blades!

https://hartzellprop.com/are-more-pr...blades-better/

The Hartzell site also discusses reasons for choosing more blades

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1