Subject: Props
From: Paul
Date: 3/6/2001, 12:22 PM


Don't know why it would work any better than any other scimitar blade prop.
The theory is if the center of lift is behind the the flexural center line
the blade will untwist.

The NASA funded Global prop took this theory to its ultimate
implementation and failed according to Power Sport that tried one.


"Ray Richardson Jr." wrote:

Dear Paul and friends;

Powersport has used the Global prop on our test stand for
2 years now. The ground adjustable blades have held up very well.
However the pitch we set the 2 blade to, for static testing were much
flatter than the pitch we would fly our RV-6A at.

We did fly with the 2 blade Global and found that at our 215 hp.
the 2 blades could not carry our power level. We changed to
a 70" x 85" wood prop from Allen Tohl's Powersport powered RV-3
to fly to Oshkosh. With 85" of pitch,  we over rev. at 200 mph.

We now make the prop hubs and blade collars for Global
and also have made the hubs for Global's 3 blade props.

To set the record straight The Global prop did NOT fail.

We exceeded the horse power level their 2 blade could handle.
and the blades would stall resulting in poor climb.
We will retest the global as a 3 blade prop when we get their
new blades. We have made over 100 blade collars for them and
many hubs so they are in use.

We changed to a 72" dia. 3 blade MT electric constant speed after Oshkosh
last year. Take-off,  climb,  top speed,  cruise 200 MPH at 2300 prop
speed/ 5300 engine. You can get the best of all worlds.
But you do pay more.

We now are a MT prop dealer and have sold 6 MT,  3 blade props to our
Powersport engine customers.

Ray Richardson Jr.
Powersport

Thanks Ray for clearing that up. I must be more careful in my choice of words. 
I did not mean fail structurally but fail to work as advertised and change pitch.

Paul Lamar
 
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