Todd Carrico wrote:

Paul

I have been following this thread with great interest.  I to am
interested in three blades, but only because I am considering a
pusher.  The EZ type AC have a noticeable "Thud" when both blades
"Hit" the wake at the same time.  Three blades just seem to be
smoother runners on these planes.

What would we have to change/Modify to make your approach work with
three blades?

I would agree with the simpler is better approach, but I personally
have felt the difference, and IMHO it is worth the extra effort/lbs.

Todd Carrico, MCSD
Senior Consultant
ARIS Microsoft Consulting Services
972-841-0077

Well the first thing you will lose is that alignment shaft.
The next thing that happens is you will need a truck and an 
engine hoist to get the raw billet onto  the mill :-)

The third thing is the CG of a pusher might be adversely 
affected. 

Three blades hubs are best made from forgings
as they are very 3D. If you have a NC 3D mill let me
know and I will see if I can come up with a housing that
might work. It is very dangerous to mess around with this
stuff as the dynamics are a deep dark mystery. If you
are willing to build a tilting test stand and run the prop
on a rotary engine with PSRU for hours and hours while the stand
tilts up and down and side to side then you just might live
through the experience.

The first thing that happens when a prop throws a blade
is the engine departs the airframe because of the severe
unbalance and resulting severe vibration. This means you 
will die as the airplane will be uncontrollable with a
way too far forward CG.

In a tractor AC if you have the presence of mind you can push over in
a vertical dive once the engine leaves the airframe and just
before you augar in.... flare to crash land. This is not something
one can practice.
 
I hate to be so upbeat about this but I don't feel I have 
the knowledge and experience to do a variable pitch three blade. 

Paul Lamar
 
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