How many blades on the prop? Variable pitch? What balancer are you using?
Is it nose wheel or tail dragger? I do some helicopter blade balancing and
have gotten funny results at times. We really have to get the helo off the
ground to do the fine tuning. Helicopter vibrations reflecting from the
ground can be misleading. I've never tried balancing a " Stuck Wing" prop.

--
Stuart Fields
Experimental Helo magazine
P. O. Box 1585
Inyokern, CA 93527
(760) 377-4478
(760) 408-9747 general and layout cell
(760) 608-1299 technical and advertising cell

www.vkss.com
www.experimentalhelo.com


"Mark Burton" wrote in message
...

Hi,

I tried to balance a prop on a O-320 on a RV-6 the other day and could
not because other large vibrations were present.

Im summary, I got:

0.7 IPS at 0.5 crank RPM

0.2 IPS at crank RPM

0.5 IPS at 3.5 crank RPM

The vibration levels at the other multiples of 1/2 crank were all
relatively small.

I can find lots of info on the web re 1/2 crank vibration and its
causes but I can find nothing on 3.5 crank and I am puzzled as to why
it is so high.

Is it normal for this kind of engine?

Thanks,

Mark