I went through the calculation for the front shaft using an online java calculator here: http://www.tech.plym.ac.uk/sme/desnotes/shaftMandT.htm
The attached screen shot shows the result of the calculator and would

indicate that the front shaft is indeed capable of taking the full
torque pulse of a 2 rotor, even if you add a significant fudge factor.
If you only ask it to take ½ the load?  Dual prop amphibian?
Decker, Michael

What stress level or material did you enter the program with?

Paul Lamar
UTS 800 Mpa
Decker, Michael


800 megapascal = 116 030.190 41 pounds per square inch
Nobody designs a crank shaft or e-shaft to run at 116,00 psi.

19 mm is a 3/4" diameter e-shaft. That is crazy :)

Yes it might not break if applied once but no engine designer
would use that number. 30,000 is more like it.

Paul Lamar


OK, but the e shaft i question is more like 30mm if I'm not mistaken.
That is quite a fudge factor, and I was also assuming 400 ftlb torque
max as you state on your site.  That is twice the actual average, and
if we want to use the front for only half the load then the max pulse
is only 200ftlb.

I guess there is only one way way to know for sure.

Decker, Michael