Accel out to 170 KIAS (Vne is 183) with nothing unusual noted
except for increased wind noise. I can definitely see the utility
of ANR headsets at higher speeds. The airplane really seems
to smooth out above about 145 KIAS and 2500 RPM. There
are also sweet spots at lower RPMs and speeds, just as there
are regions of noticeable vibration, in particular 120 KIAS and 2400 RPM.
I've been told a harmonic damper will help, and will also get some
weight well ahead of the CG - in its current configuration and
I will go out of CG limits before I overgross unless the front-seater
is hay-uge (and I'm not *that* big). I'm looking into dampers now.

Dave 'onward and upward' Hyde

RV-4 in flight test, EAA Tech Counselor
+++++++++++++++++++++++++++++++++++++++++++

If you are having thoughts of springing for the so called
$400 harmonic balancer that Mark Landoll has developed,
let me recommend that you try his $80 steel ring first.

Although I have never tried the $400 damper....
I cannot see how or why it could do anything more
than the $80 steel ring that I added to my wooden prop 150 hp
setup. Both weigh 12 lb and go a long way towards making
up for the loss of flywheel weight when you are using a
10-12 lb WOODEN prop, instead of the 40 lb steel fixed pitch
club that normally accompanies a 150-160 Lycoming.

Bottom line....
I no longer enjoy flying behind a Lycoming 150-160 engine
with wooden prop without some sort of added flywheel weight.
If you want to fly without the 12 lb ring, I recommend using
the heavier Sensenich metal prop attached to the crank.
Your butt on a long cross country will likely thank you for it,
if you are in tune with such vagaries and nuances of flight.

FWIW...
Can't beat a metal prop for flying through summer rain.
Wooden props take a real beating above 2100 RPM.

Also, engine mounts, the specific prop, its indexing, engine
baffles and tons of stuff that you would never think of can
dramatically affect vibration and the points it feels the worst.

IMO.....
If Lycoming needed a harmonic balancer, it would come
that way from the factory.... well engineered and suited for
the purpose.

You might enjoy this tidbit....
http://64.233.167.104/search?q=cache...balancer&hl=en

Lots has been written on this balancer business,
and now you have my 2 cents as well.

As always...
YMMV


Barnyard BOb - over 500 steel ring hours + ANR