I have read some discussion on the effects of different props, reducing harmonic vibration by changing the number of blades (4 blades on a 6-cylinder engine for example, vs. 2 or 3 blades which have lower harmonics) and this might be beneficial. That thought process might lead one to a 3 blade or 5 blade on an 8-cylinder engine.
Another concept which might be considered is the prop material itself, with composite props like the MT damping out the combustion shock more than an aluminium prop.
Guess that’s what makes these planes “experimental”.
Robert M. Simon
ES-P N301ES
From: Jack Morgan [mailto:jmorgan1023@comcast.net]
Sent: Thursday, June 02, 2011 8:29 AM
Subject: Re: [LML] Re: L-IV Choice of Engine
The most important issue being missed is the torsional resonance the auto crankshaft receives from the propellor. The application of viscous couplings is often tried to isolate the auto crank from the propellor with some success but the weakness still remains. . . Jack Morgan