craig a crit :
>
> If you look at the current "production" aircraft both fixed wing and rotor
> they are all moving to 5 blades or
> More, Personally I think that speaks volumes.
>
Craig, Karl and all,
Karl gave a good number of the pros and cons of 2-blade vs 3-blade.
As has been stated, drag is also to be taken into account, as well as
propulsion efficiency.
The main advantage of 3-blade props with small engines is reduced
diameter, for ground clearance or reduced tip speed (= noise and drag).
That's why 3 or more blades are used on airplane when noise reduction is
at a premium.
Apart from the above, there are few engineering reasons for adding more
blades on low power aircraft. (100 hp is not much for an aero engine).
Best regards,
--
Gilles
http://contrails.free.fr
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