Paul,
I was only thinking of the possibility of this the other day ie.

moving prop and then "shift' during climb out?

No shift but stock transmission have been used. Car transmission output
shafts are too small for prop gyro bending loads. The Mazda manual

transmission has

an output shaft only 0.8 inches in diameter. It is very dangerous to do

that.

Tracy's new shaft is 1.77 inches in diameter. The Ross is 1-7/8 inches
in diameter. The Power Sport and Marcotte is over three inches in diameter.

The bending stress in a shaft is inversely proportional to the third or
fourth power of the diameter. Most AC engines have prop shafts well over
two inches. That is why the akro guys are going nuts buying Power Sport
engines and Gear Boxes :-) PL

George Lendich wrote:

I was looking at the picture/drawing of the Power Sport provided on the
discission group
and noticed it was hollow. Are they all hollow or hollow over a certain
diameter.
I can't imagine a solid shaft of 3"
George (down under)-- 

Most all AC prop shafts are hollow to varying degrees so the simple formula
based on OD is not entirely correctly but it is roughly due to the fourth 
power exponents involved. Here is the actual formula for moment of inertia of
a hollow shaft in bending:

 I = 1/4 * pi * (Ro^4 - Ri^4)

The combined stress's due to torsion and gyro bending loads are a stress analyst
worst nightmare. Best to make it BIG.


Paul Lamar
 
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