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