Plane Talk: Great Planes Revolver .61 ARF - 2011/04

Plane Talk: Great Planes Revolver .61 ARF
WILLIAM RAMSEY
62 MODEL AVIATION
A larger 60-class sport
model with a sharp feel
a great deal of credit for building. The
Revolver 40 has to be the slickest sport
model offered today. I haven’t owned the
40, but the good news is that I’ve had my
hands all over the 60-size version—and my
Futaba transmitter has hardly seen rest since
I got the model.
Most people are in a hurry, so I’ll save
you the trouble of reading this article and
tell you that the Revolver 60 is dynamite.
And I’m flying it on the minimum-size
engine.
The O.S. 61FX has worked well and is
as easy to use as a motor. The noise is cool
(it has grunt), and I don’t have to
charge batteries between flights.
But power the Revolver with whatever
pleases you; it comes out of the box ready to
take electric or glow power, with zero
modification. In addition, you don’t need an
expensive radio or servos for the model to
groove like an expensive competition
airplane.
I’m using sport-type Futaba S9001
servos on all surfaces. Those units have a
good amount of power and are precise,
thanks to the internal coreless motor that
Futaba made famous.
The all-wood airframe is covered
entirely with MonoKote heat-shrink
material. The composite landing gear, wheel
pants, and cowling are painted to match the
covering colors exactly—even the Metallic
Blue, which I’m told is a hard shade to
match.
Assembly: I let my parts hang out in
the shop (out of the packaging)
for approximately a week
before I started
assembly. Wrinkles that
showed up in the
covering became obvious,
for Dad and me to work out.
MonoKote needs extra heat, but it cleans up
The metallic-blue
fuelproof paint on the
fiberglass cowling is a
perfect match. An included
pilot bust is painted well
enough to make the
Revolver seem full scale.
Inset: The 70-inch wingspan of the Revolver offers a light wing
loading. The semisymmetrical airfoil keeps the handling predictable.
The four-color MonoKote covering is designed with good contrast
top and bottom. There’s enough room under the composite gear to
turn a 15-inch propeller.
THE CHAT AROUND our flying field has
been that the 40-size Revolver from Great
Planes is excellent. Its wide-bodied look
adds full-scale appeal to an otherwise
tricked-out sport design. I think it would
make a great full-scale home-built.
Does that tail moment look short to you?
I asked my dad that question, and he got a
surprised look on his face. I guess he didn’t
think I knew any aircraft-design lingo.
I don’t, really, but I hear him talking
about moments while explaining models, so
it seemed like a smart question to ask. Sure
enough, he started a speech and I learned a
few things.
That short tail adds a lot of
character to the Revolver. The
way I understand it, people are
frightened of short tails because they
can make an airplane difficult to handle.
Dad’s no engineer, but he explained to me
that the short tail is tamed in this
case with a generous amount
of wing area and an
oversized horizontal
stabilizer.
The whole look of
the Revolver is a play in
aircraft feature design that I
believe earned Great Planes
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Construction is a combination of laser-cut lightweight wood and foam-core wings and
decking that is fully sheeted.
A lightweight carbon-fiber tube supports the two-piece wing
structure. The 6.0-volt HydriMax NiMH battery is strapped in
front of the Futaba elevator servo.
An included Great Planes 3-inch aluminum spinner gleams on the
front of the O.S. 61FX engine. The fuel tank was built with two
clunks: one for the carburetor and the other for filling.
The included throttle-servo tray is nested
behind the fuel tank, so that minimal bends
in the pushrod are required. Fuel tubing
cushions the tank around the included
plywood brace.
Above: The 61FX is completely hidden
inside the fiberglass cowling. Relocating the
needle valve out the side is a nice option.
This engine is easy to run and has great
power.
Near right: The author guides on the tightfitting
wings against the fuselage. A single
nylon thumbscrew through the fuselage
secures this assembly.
Far right: A Bisson Pitts-style muffler is a
lightweight option for directing exhaust
residue away from the Revolver. The
intake opening opposite the 61FX is
covered to improve engine cooling.
Photos by Michael Ramsey
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64 MODEL AVIATION
Specifications
Model type: RC sport ARF
Skill level: Beginner builder;
intermediate pilot
Wingspan: 70 inches
Wing area: 832 square inches
Length: 58.5 inches
Weight: 8.50-9.25 pounds
Wing loading: 24-26 ounces/square
foot
Engine: .60-.75 two-stroke or .81-.91
four-stroke
Motor: 1,200-watt power system on
6S Li-Poly batteries
Radio: Four channels minimum, four
to five standard servos
Construction: Balsa and plywood
with foam-core wings and features;
composite cowl, wheel pants, and
landing gear
Covering/finish: Four colors of
MonoKote with matching fuelproof
paint
Price: $219.99
Engine used: O.S. 61FX
Propeller: APC 14 x 5N
Fuel system: 14-ounce tank, Magnum
#1 fuel used
Radio system: Futaba 10C FASST
transmitter; Futaba R617 FASST
receiver; five Futaba S9001 servos; 6-
volt, 2000 mAh battery; four 9-inch
servo extensions; one power switch
Ready-to-fly weight: 8 pounds, 9
ounces
Flight duration: Exceeds 10 minutes
Test-Model Details
Pluses and Minuses
+
• A sport model with full-scale looks
(pilot figure included).
• This bigger, 60-size model has a large
wing yet is extremely aerobatic.
• Ready for glow or electric power.
• Lightweight construction that is stiff
and durable.
• Friendly flight handling.
• Two-piece wing.
• Easy to assemble. -•
Excessive gap between the cowl and
spinner.
• Fuel-proof coating needed in the fuel
tank area.
beautifully and has stayed that way.
It’s easy to tell that the construction
includes precision engineering. The model
contains super-accurate laser-cut parts and is
secured with tight joints everywhere that can
be seen.
I heard that one AMA member with a
Revolver 60 had the firewall fall out during
his first engine test. Thank goodness that the
airplane wasn’t in the air! He was able to fix
it, but I examined the airframe closely—
especially in the front end.
My airframe tested good and tight, but to
be on the safe side Dad and I coated the
firewall and fuel tank area with a layer of thin
epoxy resin. Aside from hitting it with a
hammer, trying to shake the wood parts off of
the front end seems impossible at this point.
The frame seems to have been designed
with many good ideas. The long engine box
goes all the way back to the large wing-tube
socket. Also in that general area is the landing
gear reinforcement. Like an interlocking
puzzle, every part does its job and supports
the structure around it.
Lightening holes are everywhere; if the
Revolver were built from a kit, I’ll bet that
you could produce another model from the
parts punched out of all the holes in the balsa
and light plywood.
The large wings plug into the fuselage, and
a large hatch was smartly built into the top to
allow you to get inside the model. The hatch
is roughly half the size of the airplane, and it
makes it easy to service every accessory that
is strapped or bolted inside. The hatch and
rear deck are made from exceptionally light
EPS (expanded polystyrene) foam that is fully
sheeted with thin balsa.
All lifting and control surfaces are
completely sheeted, and all have a foam core.
I understand that this makes the wing light
and strong with the fewest number of parts.
Plus it’s an easy way to make a wing as
efficient as possible, because the airfoil is
consistent.
The Revolver uses a semisymmetrical
airfoil. That means that the model is aerobatic
but stable at slow speeds, such as during
landing.
Another thing I really like about the foamcore
construction is the stiffness and precision
of the control surfaces. They have no warp
and are easy to center on the bench, because
their TE aligns with the flying-surface tip
extensions.
I want to say that building this ARF was a
perfect experience, thanks to this bonus
accessory called instructions. My dad actually
caught me studying these instead of doing my
homework and didn’t complain one bit. The
photos in the manual did most of the teaching,
but the text answered any questions that came
up.
The included CA hinges are installed in
factory-made slots, so my least favorite part of
the assembly didn’t take too long. Dad went
the extra mile, and I have to thank him, by
sealing the hinge gaps with narrow strips of
matching white MonoKote. He told me that if
I wanted the Revolver to groove as intended,
that expert step would make a serious
improvement.
The only build point I have to pick on
Great Planes about is its distance
recommendation for the engine. The stated
measurement left me with an ugly gap
between the cowl and included aluminum
spinner that was thicker than 1/4 inch. I’m used
to tighter gaps than that. When you build your
Revolver, confirm that the gap is what you
like before you drill the engine mount.
Procedures, measurements, and
recommendations were good for the rest of
the airplane.
The giant cowling completely hides the
engine, but the required cooling exits take
up a lot of space on the bottom. To make sure
that cooling air saturates the right spot, a
cover was glued over the left-side intake
opening. The cover is finished in gloss
black and held in place with flexible
silicone adhesive. My O.S. runs nice and
cool.
Even with the lightest engine bolted up
front, my five-cell receiver pack ended up
being located behind the CG. The interior
is wide open, so if your Revolver doesn’t
balance right away, there are several
ballast-location options and still room
inside the fuselage to clap the “Mickey,
you’re so fine” song.
To be honest, I didn’t want to go with
the smaller engine in my Revolver. I
begged for the .75, would have given my
braces for a .91, and would have sold my
brother for a four-stroke.
In the end the 61FX was threadlocked
into the nylon beam mounts, and I bet my
dad a replacement engine that I wouldn’t
like it. And you know what? I like my O.S.
.61—a lot.
It’s easy to start, and the needle, which
I didn’t have much experience with, turned
out to be simple to set. Dad played with
the low-speed screw during the first tank
run and was able to get the idle extremely
low—count-the-blade-going-by low.
We also played around with propellers.
Because the Revolver has such a large
spinner, the normal 12 x 6 seemed stubby.
There’s plenty of clearance for a 15-inch
propeller, so we dug through the box of
spare Master Airscrew and APC blades to
find the perfect thrust maker.
It’s great that we have so many
propeller choices these days. I’m told that
it didn’t used to be that way.
A 14-inch propeller looked perfect on
the Revolver 60. The big blades kind of
finished off that home-built full-scale
look.
A Master Airscrew 14 x 4 had painted
tips that made it easy to see, and the low
pitch helped the .61 to quickly spin up the
propeller to 12,000 rpm. It was noisy,
though—noisy enough to scare the riders
at the nearby motocross dirt track. We
switched to an APC 14 x 5N and kept the
thrust, but gave up that monster scream.
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Flying: You know that the test flight is
going to go your way when the postage
scale tells you that a model comes in at the
bottom of the advertised weight range.
Another good sign was that the engine
ran like a top and tuned in with no
complications whatsoever. It also ran
cleanly, thanks to the long exhaust stacks of
the Bisson Custom aluminum muffler that
Great Planes recommended in the manual.
I found out what pilots mean when they
tell stories about models flying off of the
bench. My Revolver 60 literally flew off of
the runway with merely the application of
power—and only half throttle was needed,
at that. Its departure from the field was so
smooth that I almost didn’t want to interrupt
it, but the time came to turn.
The Revolver is happy being solely a
crank-and-bank machine. But if you want to
get all precise about it, it likes a pilot even
more when rudder is used to adjust the nose.
The Futaba 10C radio has triple-rate
capability, so not only did I have the
recommended low and high rates at my
command, but there was also the option to
select “stupid” rates and have 3-D control.
We also added elevator-to-flap mixing,
flaps, and spoilers. Cool, huh?
All of those mixing toys are fun and are
good practice for setting up other aircraft,
but I learned that the Revolver 60 flies
great with none of that stuff. A bit of
exponential makes the high rate feel
slightly more comfortable; the model is
almost as comfortable as a trainer on low
rates with no exponential. It’s smooth,
doesn’t get tossed around by the wind, and
is teaching me how to appreciate precision
flying.
The recommended servos offer all kinds
of control authority to do whatever I want,
no matter how fast or how slow. The
standard servo even works great on the
rudder, because I can do knife-edge loops
all day long with it—inside the 10 minutes it
takes to suck up a tank of Magnum #1 fuel.
The recommended CG feels to be in a
good spot, and I think that moving it back is
possible if you want to fly the Revolver
better in 3-D. As I mentioned, flaps and
spoilers are cool but completely
unnecessary for landing; this model slows to
a crawl. The composite landing gear has a
nice “spring” to it, and the wide spread of
the wheels makes ground-looping almost
impossible.
The good news is that Dad doesn’t owe
me a new engine. I’m keeping my Revolver
just the way it is. MA
William Ramsey
[email protected]
Manufacturer/Distributor:
Great Planes Model Manufacturing
Box 9021
Champaign IL 61826
(217) 398-8970
www.greatplanes.com
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