Excuse the 'Jackanory' element here...
Whilst sweating my ar5e off in a hotel room, I stared at the ceiling fan above me and thought "if they put more blades on this thing it would push more air towards me and keep me cooler."
I came to the conclusion that adding prop blades would eventually make the whole setup less efficient due to drag and strain on the motor, and that therefore there was an 'optimum' amount of blades (and their AoA etc.)
Could someone clarify (or provide formulae for) the above?
Why is it that some helicopters use only 2 blades (jetranger[?}) and others need more? Likewise for propeller aircraft. What are the implications for adding more blades to a prop and at what point does it become ineffecient?
Ta
Chris