Superior RC Extra 330L - 2011/06

much less challenging than is usual with most
large ARFs.
Wing and stabilizer carbon-fiber spars are
already mounted into the fuselage. The
cowling mounts are factory-installed, as are
the phenolic rudder control horns. A complete
hardware package, including extra Oracover
in all colors on the model, is packed in the
gigantic box.
Tools, radio equipment, engine, and a
short length of extra fuel line are all that you
need to finish this model.
Equipment: The review 330L is powered by
the BraveHeart BH50. This 3.75-pound 50cc
gas engine produces 5.2 horsepower at 6,500
rpm and comes with an effective muffler,
standoffs, and an electronic ignition system.
The BH50 has proven to be reliable, idles
well, can hover the big Extra, and provides
decent verticals. At only
$300, it is incredibly
cost-effective.
Since the onboard
battery system was
planned to be four times
redundant, I installed
two Spektrum 2S2P
4000 mAh Li-Poly
battery packs. I wanted
to reduce setup
complications by
eliminating the ignition
battery.
Since most of the
servos were 6-volt units,
both batteries also
needed voltage
regulators. With the
usual setup, this requires
two radio switches, an
ignition switch, and two
WALTER EXTRA manufactures some of
the most exciting and competitive business
and aerobatic airplanes in the world. Among
his best is the Extra 300/330 series of
aerobats.
The world’s fastest production,
nonsupercharged piston airplane is his
330LT. The 330SC is the current world
aerobatic champion, and the 330LC is
considered one of the best aerobatic twoseaters
available.
The one aircraft that Mr. Extra does not
produce is a 330L. Yet the modeling world
features hordes of various 330Ls, and one of
the most interesting is the 29% version from
Superior RC.
In addition to its all-wood laser-cut
construction, extreme prefabrication, and
attractive cover scheme, the Superior RC
Extra 330L features a high-performance,
scalelike control surface hinge system.
Known as the “Pocket Hinge System,” a
2mm carbon-fiber rod passes through
phenolic bearings to mate the control
surfaces. The control surface LE is rounded,
nesting tightly against the fixed surface.
The result is a sealed, gapless joint that
eliminates flutter and reduces air drag while
increasing the effectiveness of the control
surface. By using this hinging system, all
control surfaces are capable of up to 60°
movement.
The ailerons and elevators are installed at
the factory, and mounting the impressive
rudder requires approximately 75 seconds.
The rudder on this 90.5-inch-wingspan
airplane is massive. It is also extremely
effective—more so than that on any similarsize
aerobatic airplane I have owned or flown.
The majority of work has been completed
by the time you remove the 330L from the
box. The tasks that remain for you to do are
regulators. Enter the remarkable Tech-Aero
Designs’ Ultra IBEC Ignition Battery
Eliminator Circuit.
This programmable gem powers the
engine’s ignition system from one or two
receiver batteries with regulators all on a
single switch. The ignition and receiver
voltage outputs can be set anywhere from 5-
6.5 volts (I set both at 6 here), while the input
voltage can be as high as 13 volts. There are
four filter stages that eliminate possible
capacitive discharge ignition (CDI)
interference.
Twin batteries with voltage regulation,
ignition battery gone, extra CDI filtering,
ignition control from the transmitter, and an
on/off light, all in one system? Sign me up!
For this airplane I chose the new Hitec
HS-7955TG and HS-7950TH (rudder)
titanium-gear, coreless digital servos. These
Superior RC Extra 330L
FRANK GRANELLI
The light, strong airframe is covered with many metallic
Oracover colors, including checkerboarding on the underside.
The hardware package even includes extra covering and a
carbon-fiber spinner.
58 MODEL AVIATION
A versatile, well-rounded
50cc aerobat
The Extra goes exactly where it is pointed and looks good
doing it. The rudder has ample authority, with little
required for knife-edge flight.
06sig2.QXD_00MSTRPG.QXD 4/21/11 10:57 AM Page 58
June 2011 59
Photos by the author
Above: The Pocket Hinge System is scalelike, and it
significantly increases control effectiveness and
precision.
Right: New Hitec titanium-geared digital servos
provide plenty of control and essential exact
centering needed to fly the 330L to its full potential.
ultrastrong units feature dual ball bearings,
fast transit times, and, most important, superprecise
digital centering.
Exact servo centering is all-important in
this type of model. Imagine trying to fly the
330L in a straight line, with its superresponsive
control surfaces, while the giant
rudder is slightly offset or an aileron is
hanging—impossible!
The 333 ounces of torque at 6 volts that
the 7955TGs produce eliminates the need for
twin aileron servos on the Extra, although the
wing does have twin servo mounts and the
extra linkage hardware. Those units are also
very fast, at .15 second.
On the rudder the 7950TH produces 403
ounces at 6 volts in .15 second. Later, when
run at the full 7.4 volts, this servo will speed
along at 0.13 second, producing 486 ounces
of torque. Knife-edge loops, anyone?
Although the 330L’s onboard power
requirements are small, I used the JR R1222
12-channel receiver that can handle 10 volts
and 35 amps of current. It has dual battery
connections and a data port, allowing me to
monitor what is happening inside the model in
flight. The trusty ol’ JR 12X transmitter will
easily handle all control and trimming tasks.
Assembly: Starting with the wing, ailerons
are preinstalled using the Pocket Hinge
System, requiring only servo installation. The
light, precise linkage is included and is close
to the perfect length. Use a servo arm that is at
least 1.25 inches long for maximum aileron
movement.
Mounting the engine is the first task.
Superior RC provides mounting templates for
Desert Aircraft 3W-50i and DA-50R engines
in the instruction booklet. The template for
the BH50 engine is available on the website.
The longest offsets supplied with the
BH50 are too short by 8mm (.315 inch). Four
1/2 x 1-inch maple blocks were epoxied to the
firewall for spacing. When installing the
aluminum firewall braces, bolt the front
section on and then drill the side mounting
holes to ensure that the braces are held tightly
against the firewall.
Cowl mounts are installed at the factory,
but the cowl mounting holes must be drilled.
They should be 11.5mm (.453 inch) forward
from the cowling rear edge.
Although instructions place the throttle
servo inside the firewall extension, I
positioned it just to the rear of that along with
the choke servo for easy access.
The BraveHeart engine’s choke lever
rotates fore and aft. Rather than install a
complicated bellcrank arrangement to place a
choke actuating rod out the side of the cowl, I
installed a choke servo to perform this task. I
had to do something to justify all those
surplus receiver channels, didn’t I?
Elevator servos mount inside the stabilizer
halves, and those mount on a carbon-fiber
spar and bolt into factory-installed blind nuts
in the fuselage. The same light, precise
linkages as are used with the ailerons are used
to control the elevators.
The elevator halves must travel the same
distance and be level at all times—up or
The linkage hardware is light, precise, and durable. Position the control horn, mark it,
and use the topside washer to center the bolt hole in the underside for perfect control
horn placement.
down. If not, the Extra will never perform
correctly, because it will always be trying to
roll with elevator input.
Before installing the rudder, tape two
straight balsa sticks onto the elevator tops;
they must be positioned to meet on the
fuselage centerline behind the vertical fin.
Adjust the elevators until the sticks are level.
Move the elevators up and down. The
sticks should remain level throughout their
travel range and at the endpoints. If they
don’t, adjust the elevator control horns, and
then make endpoint adjustment. If all else
fails, use point mixing until the sticks are
synchronized.
A few pilots might prefer to deviate from
synchronized elevator movements to
compensate for varying torque changes during
maneuvers. But even this advanced trimming
technique requires starting with synchronized
elevator halves.
I found that when attaching the rudder and
its pull-pull control system, the supplied
crimp tubes were too small to allow three
cable passes through them. I substituted short
sections of 1/8-inch brass tubing. Don’t forget
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60 MODEL AVIATION
Specifications
Model type: RC scale ARF
Skill level: Intermediate builder;
intermediate pilot
Wingspan: 90.5 inches
Wing area: 1,314 square inches
Length: 76.6 inches
Weight: 18-20 pounds
Wing loading: 35.07 ounces/square
feet
Engine: 50cc (gas)
Radio: Five channels minimum, six to
eight servos
Construction: Balsa and plywood,
fiberglass cowl and wheel pants, heavyduty
plastic canopy
Covering/finish: Five colors of
Oracover with matching fuelproof
paint
Price: $695.95
Engine used: BraveHeart BH50
Propeller: Mejzlik 22 x 10 carbon fiber
Radio system: JR 12X transmitter, JR
R1222 12-channel receiver, four Hitec
HS-7955TG servos, one Hitec HS-
7950TH servo, one Hitec HS-322HD
servo, two Spektrum 2S2P 4-amp Li-
Poly batteries
Ready-to-fly weight: 20.1 pounds
Flight duration: 20 minutes
Test-Model Details
Pluses and Minuses
+
• Exceptionally wide CG range.
• High-quality construction throughout.
• Innovative Pocket Hinge System.
• Carbon-fiber spars, landing gear, and
spinner.
• Plug-in wings and stabilizers.
• Stable yet versatile performer—great
for 3-D. -•
Vague instructions, especially about
throttle-servo installation.
• Color scheme can appear dark in the air.
The Extra has two interior
configurations. One is great for 3-D
work, while the other setup allows
for smoother maneuvers and more
stable flight characteristics.
to put thin CA in the crimp tubes after
everything is set.
The rudder control horns span roughly
2.25 inches, so use a matching servo output
arm for proper centering.
Everything else is fairly straightforward.
Make sure that all control surfaces move
approximately 60° in each direction; this is
where the Pocket Hinge System really shines.
The 330L required 1.25 pounds of fishing
weights to balance at the 160mm CG point.
The BH50 is on the lighter side. The aircraft is
configured for a canister muffler, but I used the
stock muffler instead. Both factors combine to
reduce nose weight, thereby requiring the extra
lead.
The result of close to 30 hours of work is an
attractive big airplane that doesn’t merely show
up at the flying field; it makes an entrance!
Flying: This Extra has two internal
arrangements. The stock layout places the
receiver and fuel tank behind the CG as
outlined in the instructions. When balanced
with an empty tank, Above right: The BraveHeart BH50 the model in this
engine has proven itself to be an
excellent low-priced power plant. It
is an original 5.2-horsepower, 50cc
design that is specifically for use in
RC airplanes.
Above: The Tech-Aero Designs Ultra
IBEC Ignition Battery Eliminator Circuit
works flawlessly. It combines both
receiver batteries and their voltage
regulators, eliminates the ignition
battery, and provides a transmittercontrolled
engine shutdown, all while
using only a single on/off switch.
06sig2.QXD_00MSTRPG.QXD 4/21/11 10:58 AM Page 60
tendencies, as are common with most tailheavy
airplanes. It is just that the nose has to
be “held down” with elevator.
As fuel burns off, so does 3-D
performance while the 330L slowly
becomes more tractable as it regains pitch
stability. Landing after a 20-minute flight
(the BH50 uses little fuel) is normal. With
the tank nearly empty, the model is back in
balance and easy to fly.
The Superior RC Extra 330: handles a
tail-heavy condition better than any model I
have ever flown. But—there has to be a
“but”—although it flies 3-D far better than I
can, it will not fly “pretty” in the tail-heavy
condition.
The control surfaces are too large and far
too effective for smooth maneuvering with
an aft CG. Even when control surface
movements are reduced from 60° to only
10°, slow rolls and knife edges walk badly,
snap rolls are awkward, the elevator is far
too effective for flying smooth maneuvers,
stall turns require a deft touch to avoid their
turning into rudder loops, and landings are
10 mph faster than they should be.
That is common in many models that are
designed and trimmed for 3-D work. I am
addicted to flying pretty, so something had
to change.
Remember my mentioning that this
aircraft is unusually tolerant of CG changes?
Well, it truly is! So I made a new, removable
fuel-tank position directly forward of the
CG.
This makes the Extra slightly nose-heavy
when the tank is full. That little change has
made all the difference.
Going to lowest rates on the 12X reduces
elevator travel to 18°, ailerons to 14°, and
rudder to 30°.
With the now-forward CG, the 330L will
fly the most beautiful loops and Avalanches,
awesome stall turns, barely in-sight to nearly
out-of-sight slow rolls, and knife edges with
little walking.
Multiple fast rolls are simple to keep in a
straight line. Almost zero down-elevator is
required when inverted. Outside snaps can
be stopped on point almost by single-digit
degrees. Spins might appear nearly flat,
while altitude loss during the spin is less
than expected.
During one flight the airplane flew into
what was supposed to be a normal test
spin, which morphed into a shameless
show-off maneuver because it was
performing so well in the spin.
Starting at roughly 600 feet, it flew into a
two-turn spin to the right, stopped on point,
changed to a left two-turn spin, stopped on
point, and then rotated three turns to the right,
followed by another point stop and then three
turns to the left. It then stopped rotating and
climbed straight up approximately 200 feet
more, leveled out inverted, and did opposite
two-turn inverted spins.
I had not intended to do that, but the Extra
proved such an excellent flier that it just
happened. I guess the airplane and I got
carried away with how “pretty” it can fly.
After all of that flying, the landing proved to
be slow and typical.
With the addition of the forward fuel tank
mount, I now have two models in one
package. For practicing 3-D (I am newer at it),
I fly the 330L in stock form by adding a few
inches of fuel-line extensions.
For flying pretty, move the tank and
receiver forward. This is a good deal and a
good airplane.
Plans are to reduce the amount of nose
weight by moving the rudder servo and the
twin receiver batteries forward, while
reducing tail weight. This should reduce the
nose weight required to nearly 16 ounces.
The Superior RC Extra 330L is versatile,
and exploring that versatility is going to be a
lot of fun. MA
Manufacturer/Distributor:
Superior RC Model Distributors
Box 514
Long Lake NY 12847
(518) 624-2478
www.superiorrc.com
Sources:
Spektrum
(800) 338-4639
www.spektrumrc.com
Tech-Aero Designs
7 Parkview Rd.
Randolph NJ 07869
www.tech-aero.net
JR
(800) 338-4639
www.jrradios.com
Hitec RCD USA
(858) 748-6948
www.hitecrcd.com
June 2011 61
The author with the Extra, giving you an idea of this aerobatic machine’s size. It always
attracts a crowd at the flying site. Ann Granelli photo.
configuration is slightly tail-heavy once fuel
is added.
My experience is that this is an intentional
design to enhance 3-D performance. With
fuel in the tank, the 330L flies normally at
speed. When throttled back and slowed, it
drops its tail and is ready for 3-D work.
This airplane’s torque rolls are far better
than I can fly. With the tail wanting to drop,
full-power Blenders are impressive.
Waterfalls are easier to perform, as are knifeedge
loops. The rudder is as impressive in its
performance as it is massive.
In fact, all control surfaces are extremely
effective. The Pocket Hinge System seals the
gaps, increasing control response even at
exceptionally slow airspeeds.
Sealed controls also means that all control
surfaces are equally useful, making the
aircraft’s response curve predictable and
constant. As an example, the Extra has no
wing-drop tendencies when entering the Wall
maneuver, because no air spills through an
elevator or aileron gap.
However, you pay a price for the 3-D
performance. Landing after only eight
minutes aloft requires the pilot to hold downelevator
during the approach. Flaring is
accomplished by releasing down-elevator. If
your transmitter allows it, mixing in one or
two points of down-elevator with idle throttle
does tend to normalize landing control inputs.
Although it’s unusual for many fliers who
are unaccustomed to 3-D-trimmed models,
the Extra’s full-fuel approach is steady and
controllable. There are no dangerous
BraveHeart
BH50
This engine produces 5.2
horsepower at 6,500 rpm, which makes
it slightly more powerful than some of
the other readily available 50cc power
plants. Testing has shown that its best
idle speed is near 1,300 rpm. Using the
Mejzlik 22 x 10 carbon-fiber propeller,
the rpm tops out at close to 7,400.
Complete with included muffler,
the BH50 weighs only 3.75 pounds.
The CDI operates on voltages from 4.8
to 6.0. Useful propellers range from 22
x 8 to 24 x 8.
According to Superior RC, this
engine is an original design and
features a Walbro carburetor. It is
priced at $300 and comes with a threeyear
warranty serviced by Superior
RC, which is located in New York.
The BH50 can hover the 20-pound
Extra 330L and then climb away.
During the course of many flights so
far, this engine has proven to be
reliable. MA
—Frank Granelli
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