Paul,
snips..
By the way, it is a real thrill, while also a bit scary to be flying
around
above the clouds in an "experimental" airplane that you put together in
your
garage and which uses a car engine along with a whole bunch of
do-it-yourself parts. You can't help but wonder if you did everything
correctly as one snafu could easily ruin your whole day. With that said,
I'm
beginning to feel a bit more comfortable about the whole experience now.
But
give me a couple-hundred hours of trouble-free flying and then ask me how
I'm feeling.
Mark
15 hrs (and counting)
My mother told me never to fly anywhere unless I could
see the ground :)
Things happen. Plan on it. I am not supposed to be
saying that on here but never the less always have a plan B.
Judging by what I have seen so far of your excellent
installation I think you have less to worry about than most.
BTW what are you seeing on the "cylinder head" temperature
gages so far? You are our only experimenter on those.
How is the muffler working out?
--
Paul Lamar ...No rotor no motor.
Paul,
Thanks for the vote of confidence.I try to fly high so that I
have more options, just in case.
I haven't looked at the CHT's in a while as you must page through a number
of screens on the EM-2 to get to the EGT/CHT page.Not much you can do
about
it anyway.I like to keep the main page up during the initial climb, but
the
most important info is on the top and bottom lines which don't change when
paging. The EGT's typically run around 1600-1650 in cruise. I'll check the
CHT's on my next flight and let you know what they're reading.
The " R.B.Wagner" exhaust tubes seem to be holding up just fine also. So
is
my homemade auger muffler, although guys tell me that they can hear me
coming from 5 miles away. I tested a Hush Power II resonator muffler and
it
is amazing how much quieter it is over the auger muffler. For the first
time
I could actually hear the prop above the exhaust. The body of the muffler
is
only 12", overall length is 17.5" but a couple of inches can be cut off
both
ends to shorten it. It is compact enough to fit under the cowl. I couldn't
bring myself to hang a muffler under that beautiful airframe. This
provides
a good alternative. Dennis H. has one of these on his RV-7A and it is the
quietest airplane on the field. Now that's something you don't hear often
when discussing rotaries.
By the way, a side benefit to the oil/water exchanger is that the oil
keeps
the water hot enough so I don't need a thermostat or cowl flap. Yesterday,
I
flew and the oat was 44* F.The coolant was up around 170-175 in climb and
settled down to 150-160 in economy cruise.Oil temps track 10-15* higher.If
it gets much colder, things may change and I may have to add a cowl
flap.The
20B burns about 12.3 gph in economy cruise.Not too shabby, especially
since
I can burn auto fuel which is more than $1/gallon cheaper.
Mark S. 16 hrs
There is no cheap replacement for thick RB Wagner SS exhaust
pipes :)
You certainly have plenty of cooling capacity in the winter
time :)
12.3 gph is 73.8 pounds per hour so at a well leaned BSFC of
.47 (150 F lean of peak.) that would be about 160 HP. At .5
BSFC it would be about 150 HP. At that HP rate the 3 rotor
TBO should be 5000 hours :)
How fast are you going at 12.3 gph and what is the EGT?
--
Paul Lamar ...No rotor no motor.
Paul, That was cruising in overdrive.;-) Best I recall, it was about
105-110 kts indicated, 123 kts TAS (142 MPH) and about 17" MAP, highest
EGT
was 1600 +/- .I'll verify that again on next flight. I'm still working on
getting the EM-2 fuel totalizer calibrated. I know I'm close, but not
quite
there yet. Best cruise speed I've seen so far is 173 kts TAS (200 MPH).
This
was at 1700 prop rpm, 5200 engine rpm, wot and no wheel pants.I can't wait
to see what it will do with the wheel pants installed and higher
prop/engine
rpm. That M/T c/s prop sure makes things nice. I usually set the prop to
2250 for takeoff. That gives me almost 7,000 rpm for takeoff. She's
usually
airborne before I hit the first turnoff. Once I'm up to about 110 kts I
start dialing the prop speed down to reduce the stress on the engine and
psru, and also to lower the fuel burn. I usually see about 26-27gph (
160#/.6 BSFC = 265 HP.... 160#/.65 BSFC = 246 HP) on the EC-2 during
initial
climb. It usually climbs in excess of 1500 fpm at 105-110 kts. Not too bad
for a 4-place airplane. I haven't done a full-power climb at Vx yet.
Mark
Thanks for the performance data. I'll have to do some data reduction. I
assume you have the 2.85:1 PSRU since you can reach 7000 RPM or can you do
that with a 2.17 :1 PSRU?
My C182 cruises at about 150 MPH on about the same 12 gph fuel burn.
Of course it won't cruise at 200 MPH :)
--
Paul Lamar ...No rotor no motor.
Paul, I flew again today, my first official cross-country in a
rotary-powered airplane.I flew from Lockhart (50R) to Taylor (T74),
staying
outside of the ABIA class C airspace.It took an hour from engine start to
"clear of the active" and I burned approx. 11 gallons according to the
capacitive fuel gages (on the ground). I managed to snap a couple of shots
of the EM-2 and EFIS for your viewing pleasure.The TAS readings differ a
bit
between the EFIS and the EM-2. The oil & coolant temps to pay attention to
are the ones on the EFIS.The EM-2 oil temp is the temp after the oil/air
cooler, but before the oil/water exchanger.The EM-2 coolant temp is the
return coolant temp, after the radiator (returning to engine).You can see
that the coolant and oil temps (shown on the EFIS) are within about 10* of
each other.
The highest EGT is shown on line two and is rotor #1 (nearest the
flywheel)
and is at 1647*.The two bars to the right of the #1 show a graphical
representation of the EGTs (#2 is not working as is evidenced by a gap
between the #1 and $3 bars).I checked the CHT readings and the highest was
also #1 (nearest the flywheel) as I would have expected.It was reading
195-200*.The fuel readings (lower right of the EFIS) were Left - 33
gallons,
Right 29 gallons when in the hangar before the flight.You can see that the
left is reading 25.5, which is pretty close, but the right has gained 7
gallons and is reading 36.1 gal.Maybe I should apply for a patent.:-)All
kidding aside, I really need to get this corrected. I'll be trying out
your
suggestions soon.Mark 17 hrs
Congratulations on the first cross country. Is that CHT 200 C or 200 F
Mark.
--
Paul Lamar ...No rotor no motor.
Paul,
That would be 195-200* F.
Mark
Amazing! At that rate we are a hardly using these engines. A piston engine
CHT runs up to 400 F. I sure hope those thermocouples are working right.
If
so I suspect 400 HP would not be out of line for a p-port 3 rotor aircraft
engine. Maybe 500 HP with a 3:1 PSRU. At that level we would be pushing
turbine engines in power to weight ratio with 75% of the fuel burn. I
wonder
when this is going to dawn on a major aircraft company. Just think what
Wankels could do with a turbo compound.
CHT is the one parameter that measures the capability of the engine to
generate HP long term. We are just seeing the tip of the iceberg on the
potential of Wankel aircraft engines.
Paul Lamar ...No rotor no motor.
Van is always harping on people about adding HP to his designs. He
assumes
they are going to install a larger displacement and consequently heavier
aircraft engine. In a rotary that is not necessarily true. HP can vary
over a wide range depending on how it is tuned. A p-port or turbo can
drastically increase the HP with little or no weight penalty.
The six pinion Ford planetary set is completely up to the job assuming it
is kept cool enough. It is used in the Ford A4OD auto transmission and
deals with 650 foot pounds of engine torque output by the Power Stroke
diesel. The max torque you will see out of a NA 3 rotor is 240 foot
pounds
and it is orders of magnitude smoother than a diesel engine. Gear sets
are
designed around torque. The amount of HP they will tolerate depends on
how
cool you can keep them.
The only thing I don't like about Tracy's PSRU is it uses high pressure
hot
engine oil to lube it. If it had all roller or ball bearings it could be
lubed with a separate oil supply fed through a small oil cooler and
recirculated at low pressure. Gear lube designed for the job could then
be
used.
Synthetic oil such as Mobile One will help. Regular engine oil breaks
down
around 220 to 250 F and the temperature of the oil in the line contact
area
of any gear set can easily exceed that temperature. That local hot spot
oil
is then combined with the rest of the oil in the gear box so it will not
show up in the measured oil temperature directly. Mobile One, according
to
my half hour oven test, does not break down until about 400 F to 500 F.
You
can run this test yourself. Put a teaspoon amount in a small can in your
kitchen oven when the wife is not around.
What you can do with Tracy current system to improve it is add another
small oil cooler in the high pressure line from the engine going to the
gear box. The back lash is also a function of the spline fit or wear as
there are several splines in Tracy design. Here is a design that does
away
with all splines. The sun gear is attached to the damper plate directly.
Keeping track of the oil temperature exiting the gear box is another
option.
The vibration is normal with Tracy's damper. It is the gear box over all
torsional stiffness resonating with the rotational inertia of the prop.
The lowest idle RPM is a function of the shore hardness of the rubber
bushings used in Tracy's torque damper. Softer rubber bushings will lower
the resonant frequency. I suggest silicone rubber bushings as they will
tolerate 500 F while regular neoprene is limited to about 200 F.
It won't hurt the engine to idle it above 1800 RPM. Your prop RPM with
a 2.85:1 PSRU of course is only 631 RPM which is lower than the idle
speed on my O-470.
--
Paul Lamar ...No rotor no motor.
Paul,
"HP can vary over a wide range depending on how it is tuned. A p-port
or turbo can drastically increase the HP with little or no weight
penalty."
Wouldn't it be better to just peripheral port the engine as 75% of 400
is more hp than 75% of 300 hp. And it would be lighter and much simpler.
Mark
That is the simple way to go no doubt. But up in the real high
flight levels you might still need a turbo. I think Steve Veach is
on to something with a Lancair 320 turbo 2 rotor. That could be
a very fast combination up high. Perhaps as much as 300 MPH.
I thinking of selling my Kis Cruiser kit and my C182 and
buying a flying Lancair 320.
Paul Lamar
Concerning in flight failures - they happen even to the federally blessed
birds:
http://www.aero-news.net/news/genav.cfm?ContentBlockID=91b77742-7f20-4476-9787-acfec306c5bc&Dynamic=1
Cheers,
Matt-
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