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What 4-blade prop produces similar levels of thrust to a 6x4 2-blade?

#1
I am building a P51 Mustang with an MT1806 motor (powered from a 2s battery). I have a 6x4 propeller that produces a good amount of thrust with this setup. However, for accuracy reasons, I really want to install a 4-blade (yes, I know it's less efficient). What size and pitch propeller is good enough to produce about as much thrust as the 2-blade?
 

FDS

Well-known member
#2
I wouldn’t put a 4 blade on a mini, you will kill the efficiency a lot vs running a two blade. You have a relatively small battery and motor in minis, when it’s flying you cant see the prop anyway. If you want scale fidelity build a bigger one as the lower wing loading will cope better with a multi bladed prop. You would certainly want 3s with a smaller multi bladed, low pitch prop. They don’t make many “scale” props in small sizes either. The closest thing you might be able to run would be a set of 4 blade 5x3 props. These HQ ones might just work on the motor you have, but test the heat in the motor ESC very carefully and fly a short flight before checking the battery voltage as well.
https://www.racedayquads.com/products/hq-prop-4
A spinner will improve the look of the plane if you want a compromise, and you can paint the tips of the prop without messing up the balance too much. Be careful with spinners that cover the motor and block airflow, as that will result in overheating.
 
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quorneng

Well-known member
#3
Wole Oyeyele
If you are really concerned at accuracy not only a 4 blade but the right diameter as well. One without the other is a bit pointless for scale effect.
The problem is a 4 blade of something like the right diameter (6"?) will require twice the power from the motor which it will not be able to provide.
To deliver the same power with the scale diameter would require a motor that turns slower with a rather lower kV value of the current motor. I doubt such exists without it also being quite a bit heavier so you would actually need more power to compensate for that as well as the lower 4 blade efficiency. You then might need a bigger battery too. Can you see where this is going?

As FDS says it may possible but the attraction of staying with the designed prop and motor is strong.
There is of course nothing stopping you fitting a scale four blade prop to look at, just don't fly with It.;)