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From: "Al Gietzen" <ALVentures@cox.net>
To: "'Rotary motors in aircraft'" <flyrotary@lancaironline.net>
Subject: RE: [FlyRotary] Re: Tips on tuning
Date: Fri, 3 Aug 2007 16:36:29 -0800
Message-ID: <000001c7d62f$7fb19560$6400a8c0@BigAl>
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I'm all for 3 or more blades because there is more surface area to=20
impart thrust from. Since we have a prop disc limit of 66 inches on our=20
airframe, adding blades is the way to go to improve thrust. There is a=20
limit to the amount of HP a given blade can absorb and transmit. I=20
wouldnt necessarily be opposed to trying a 6 blade variant either,=20
provided we are making full power with our engine, or later with the =
turbo.

David;

I'm quite certain it is not as simple as more blades equals more thrust.
More blades equals more rotational drag, and each additional blade =
getting a
smaller "bite".  If you are allowed the diameter needed to absorb the =
power,
two blades usually gives you the highest top speed.
But a 3 blade is nice for a pusher; the general opinion is it is =
smoother
than 2 blades because both blades are not in the wing wake at the same =
time.

Al