2 vs 3 blade props

[Wayne Galligan]

I  have recently been experimenting with 2 and 3 blade props on my OS 1.40
in my Entropy.   I was trying to get this airplane to fly similar in speed
to my Aries as the Aries is a wide body and there was too much difference in
the speeds between the two airplanes.  I have not had the chance to use one
of Dave Lockharts prop but this is what I am using.

3 blade 16x11  GSW c.fiber
3 blade 16.5x12 Bolly c.fiber
2 blade 17x12 reg APC
2 blade 17x13 reg APC

15% Cool Power and c.fiber proto-type pipe by AeroSlave.

The 3b 16x11GSW gave good performance both top end(8350rpm) and on downline
braking.  It is 1 oz lighter then the APC so it would accelerate quicker and
had good vertical. I had balance issue using this prop as I was at the back
of my c.g. already.  I flew this prop at the Houston Contest with good
results.

The 3b 16.5x12 Bolly had similar performance to the GSW but was noisier and
sounds much different then the other props.  A sound that I didn't like. It
made kind of a burbling like noise but engine was running fine.  This prop
has narrow blades and does not seem to have more pitch then the GSW even
though it was a 12 vs 11 pitch.

2b 17x12  APC works good in windy conditions and most all around flying.
This prop needs a little more throttle management as it will  unload more
then the 3 blades or 17x13.
and it was the right prop at Lubbock at altitude and after carb adjustments.

2b 17x13 APC  seems to be close in comparison to the 3 blades in downline
braking when the pipe and mixture is set right.  It is much quieter of all
the props and is more linear in throttle response.  I liked this prop best
on the Entropy that I am flying that is not as wide a body as some of the
new planes and is a little faster then like my Aries.

Pipe tuning is definitely an issue when switching props so best results may
not be seen unless you retune.   So far the APC 2 blade 17x13 has gotten the
nod from me until I get one of  Dave Lockharts 3 blades to try.

Wayne Galligan

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