Hi Jean,
How about using a 20B engine mounted tranversly. Drive one side off the
flywheel end and the other off the front of the e-shaft. This would be a
lot lighter than twin engines and the rotars seem to be bullet proof. It
would help offset the weight of the drive. Dog clutchs on each side to
disengage if one side fails. The props would be close enough to the
center that one side disengaged would not be as bad as conventional
twins.

Dale Davies

The front part of the shaft is not strong enough.

Paul Lamar



" The front part of the shaft is not strong enough."

Would you mind taking us through the math on that?
Decker, Michael



http://en.wikibooks.org/wiki/Strength_of_Materials/Torsion

J = pi/2 x (c)^4

J is the polar moment of inertia of a cylinder.
c is the radius of the cylinder.

What that means is the strength of the shaft is proportional to the
radius of the shaft  to the fourth power. Small changes in the diameter
of the shaft have drastic affects on the strength.

The max stress on the shaft is:
stress = T x c/J

Where T is the torque in inch pounds.

Simple.

Lets say the stock shaft is 1.5 inches in dia. c = .75 c to the fourth
power is .316.

OK Lets  we go down on the diameter to 1.3 inches c2 is then .65. c2 to
the fourth power is .178! Almost half as strong.

The same thing applies to the two rotor.
Forget taking full power out of the front of the engine.

If you make a new e-shaft with a larger diameter nose you will have to
totally redesign the oil pump drive and the thrust bearings not to
mention the front cover.

There is another problem with the 3 rotor. Now the tapered joint must
take twice the torque as it is now receiving torque from both rear
rotors instead of only the front rotor.

Paul Lamar


" Forget taking full power out of the front of the engine."

You'd only be taking 1/2 out the front in the proposed situation.  What
is the torque pulse, 1200 inch pounds?
Decker, Michael

I was guessing on the diameter for purposes of illustration.
It could be smaller.

2 to 3 times average. 400 to 600 foot pounds peek on a p-port.
600 foot pounds is 600 foot pounds is 7,200 inch pounds.

If you lose the load on one side the other side would shoot up to
max power. Scary design. Why would you want two props with
one engine?

Paul Lamar

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