Matt Whiting wrote in message ...
Jay Honeck wrote:

I did a bunch of "research" (asking as many 235 owners as I could
find) about this two years ago when one of my blades failed
inspection. Almost all of them reported some sort of vibration.


I've heard this before, but I don't understand why an extra blade would
inherently add vibration?

If anything, shouldn't an extra blade reduce vibration?

I thought the same, but it doesn't appear to be the case, at least not
with 4 cylinder engines. I've read that the 3 blade props seem more
compatible with 6 bangers. Supposedly, this is related to power pulses
of the engine, .......

Yes, and four cylinder should have either two or four blades.
I checked with prop mfgs and they will generally tell you that
three blades do not get along with four bangers - especially
larger ones. One mfg essentially refused to sell a three blade
for a four banger and insisted on two or four blades.
On smaller engines like O320 a three blade is less of a problem
simply because the power pulses are much less severe than that
of a O-360 for example.

There is more of an issue than just vibration - the potential
breakup of the three blade prop with a LARGE four banger.
Any four banger O 360 or larger should not use a three blade
except wooden ones - wood can dampen the extra vibration energy.

My 220hp Franklin 6, gets hapily along with a IVO 3 blade inflight
adjustable prop - very smooth at high power.

---------------------------------------------
SQ2000 canard: http://www.abri.com/sq2000