Flight test update - long

Finding more time to go flying these days, but still less than ideal.
Up to 18 hours so far, with no major problems. I rerigged the tail a
few weeks ago to take care of some of the out-of-balance problem
and an excessive nose-down trim requirement at cruise conditions.
It really helped, so I've cut the rudder tab down to about 6" and my
right foot doesn't go to sleep as long as I stay fast.

Today was a two-ended envelope expansion flight, up to 170 KIAS
and down to accelerated stalls (up to 2g). Accel stalls are a real
non-event, as long as the ball is centered (I didn't do any uncoordinated
stalls today). I used near-idle power and about 45 deg bank and a
steady pull modulating descent rate to control bleed rate. A few knots
prior to stall there's pretty good airframe buffet, felt in the seat and
the stick. I really wasn't expecting any warning, so it was a nice
surprise. At stall the airplane rolled out of the turn, usually
to about 5-10 degrees opposite bank. Recovers immediately on
relaxation of aft stick. Most noticeable once again were the stick
displacements - I really had to horse it around at 70-100 KIAS to
get it to stall. Forces drop accordingly as airspeed decays but
are still higher than some would have you believe. This is still at
forward CG - it WILL get lighter at aft CG's. Working up to spins (soon).
A few stalls in each direction showed that the results are (apparently)
repeatable and predictable.

As it stands now I've done one incipient (1/2 turn) spin out of a stall
when I got lazy on the rudder. Recovery was immediate with a bit
of forward stick and a quick boot of rudder opposite the yaw rate.

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.

EGT and CHT have really settled down, presumably due to the
cylinders breaking in. I've still got a ~150 deg split in EGT and
a 65 deg split in CHT at cruise (#3 cyl hottest), with peaks well
below maximum allowable. I haven't let climbs at high power
go long enough to see if I'll hit limits - I throttle back based on rate
of increase rather than peak. These splits aren't bad, but I'm going
to add blockers on the front (coolest) cyls to a) direct more air over
the hot (aft) cylinders, and b) see if I can direct a little more air into
the cabin air pickup mounted on the inlet ramp in front of the #2 cyl.
Since I sealed the cockpit with weatherstripping it seals most of
the leaks, but the vent system is pretty anemic. Good for cold
days, bad for hot ones.

For those of you that talked to me about flying it at PJY, I've
been paying more attention to what my right hand is doing.
When maneuvering, even moderately, I *still* rest my whole hand on
the grip. I haven't noticed any tendency to overcontrol, and I've
got what I consider precise control. I'm not really the two-fisted
wonder I joked about at PJY, but still don't need to fly it with
a finger and thumb to avoid overcontrolling. I do have a little
experience with very maneuverable airplanes, maybe this makes
a difference, I dunno, but I'm happy with it the way it is. For
extended straight and level flight I'll sometimes rest my forearm
on my thigh, which places my hand below the grip. I can still
make small corrections this way and it's more comfortable for longer
flights. It's much more a comfort issue than a sensitivity problem.

Up next in the cards are stalls with aggravated inputs, then incipient
and developed spins, as well as a quick trip to Vne. Chute repack
is current :-) It depends heavily on weather, though, and I'll rearrange
stuff and do climbs if I can't get to 7.5K or so for spins.

Envelope so far:
0 AGL-8000 ft MSL
40-170 KIAS (200 KGS)
0-4g
1g and accel stalls

Dave 'onward and upward' Hyde

RV-4 in flight test, EAA Tech Counselor

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