REVIEW REDWING RC cc MXSR - 2012/06

The new RedwingRC MXSR
aerobatic airplane is produced by
an owner who is an enthusiastic
RC pilot. RedwingRC can sell you the
kit and the extras (such as a DLE engine
and strong servos) that you need to
complete the airplane. The company
also sells all of the major parts you
might need down the road. Not sold
are the company’s excellent online
construction/help videos—they are free!
There is a growing market for .30-
size gas airplanes that you can  t into
today’s smaller cars. You get a Giant
Scale appearance and better vertical
performance because of the lightweight
nature of the beast.
The MXSR comes in red, blue, or
yellow, and has optional decals to go
with the optional painted CF spinner.
The kit is complete and features
removable stabilizers, carbon- ber wing,
tail tubes, landing gear, optional spinner,
and huge servo-arm extensions. The
control surfaces use  berglass board,
double-truss control horns. You also get
wheel pants pre tted with a T-nut and a
pre-plumbed tank. RedwingRC intends
to save you as much assembly time as
possible.
The pushrods are all (except for the
throttle) turnbuckle style, which means
that they have left- and right-hand
threads at opposite ends. The engine
cowl has a pre tted plywood ring with
T-nuts already installed, so it simply
bolts straight onto the front.
The fuselage is ready to accept
muf er canisters, so modi cations are
unnecessary. The horizontal stabilizers
are removable for transporting it in
medium-size cars. What you may not
see is that the wing-tube sleeve inside
the wing is also carbon  ber for added
strength. (For you electric power
enthusiasts, there is a hatch in the
underbelly behind the undercarriage for
easy battery insertion.)
Most notable is what is not in the
box. The MSXR is supported by the
aforementioned online construction
videos that are loaded with coaching/
construction guidance. The videos
can be found at the link listed under
“Manufacturer/Distributor.” These
videos will help you quickly and
The MXSR, shown in a half knife-edge, presents well
and maintains stable flight even in windy conditions.
successfully construct this airplane and
get it in the air.
The videos are so good that, in most
cases, you do not need the instructions.
They leave a reviewer with little to write
about. However, to give you an idea of
the actual work entailed to complete
an MXSR, this review has been broken
down into tasks. This article summarizes
the work that you need to do beyond
what is in the box.
Ironing and Cutting
The covering was good and only
a few small places required gentle
application of an iron to reshrink the
material. You have to make a decision
about the orientation of the aileron
servos. You can have them lie  at or be
vertically mounted. This determines
whether you cut a hole in the wing or
you expose a hatch plate. You also need
to look for the hole to open up for the
elevator servos and the pull-pull wire
exits.
When you need to choose where your
switches will go, you will  nd existing
sites under the covering next to where
the fuel line dot goes. These have all been
laser cut in advance.
Gluing
Glue the hinges for the stabilizer, the
rudder, and the ailerons. You should apply
a small amount of oil to the hinge pivot
point to make sure the hinges do not stick
to the epoxy. You also need to glue in the
dual control horns. The two-horn setup
is made of epoxy board. The horns are
epoxied into each control. The laser-cut
plywood mounting plate/cradle for the
throttle servo is glued in place after the
“run” for the throttle pushrod has been
established.
Drilling
It is a good idea to predrill the servo
screw mounting holes to avoid splitting
the wood. You will also drill four holes
for the engine mount standoffs. There
can be some grinding or drilling required
when you cut any holes in the cowl. The
Mintor 33cc only needed an exit hole for
the exhaust pipe. No hole was needed
for the spark plug. Adding a small hole,
allowing long screwdriver access to the
carburetor adjustment screws, is also a
good idea. Otherwise, the cowl stayed
intact.
The MXSR comes with a carbon-
 ber undercarriage and preassembled
wheel pants. It only took two screws to
attach each wheel pant. I ground out
the clearance for the wheel tires because
front tires tend to expand when spinning
fast and can sometimes catch the wheel
pants. The drilling is done!
Screws and Bolts
Connect all of the control surfaces
with turnbuckle pushrods. These allow
for large or small trimming when
adjusting the control surfaces. Because
there is a left-hand thread and a righthand
thread on each pushrod, you can
be precise with your changes.
One tip is to use a slow electric drill
to pre-run both the right-hand and lefthand
threads into each plastic clevise
at least once. This will make manual
adjustment easier when the rods are
installed between the servo arm and the
control horn.
The fuel tank came preassembled
All of the major pieces
are pre nished. The
cowl, canopy, and
stabilizers all attach
with 3mm bolts. The
wings use a carbon-
 ber tube and
two threaded
nylon bolts to
become part of the
completed MXSR.
SPECIFICATIONS
Model type: Aerobatic
Wingspan: 76 inches
Length: 70 inches (spinner to tail)
Wing area: 1,100 square inches
Weight: 10.75 to 11.25 pounds
Construction: Carbon-fi ber wing tube, tail
tube, landing gear, tail gear,
and spinner
Price: $379 without spinner;
$399 with spinner
Covering/fi nish: UltraCote
TEST-MODEL DETAILS
Weight: 11 pounds, 4.25 ounces
(including radio equipment,
telemetry overhead, and
engine, but no fuel)
Center of gravity: Set at 127mm for initial fl ight
Radio system: Spektrum A6030 x 4,
JR 537 (throttle), JR8711
(rudder) servos; AR8000
receiver; JR 11X transmitter
Motor: Mintor 33cc
Propeller: Mejzlik 19 x 8 with aluminum
spinner
Receiver battery: 2600 mAh 2S 8.4-volt LiPo
with Turnigy BEC 5.2-volt
switching regulator
Ignition battery: 1500 mAh 2S 8.4-volt LiPo
with Turnigy BRC 5.2-volt
switching regulator
PLUSES
• Ease of build.
• Lightweight construction.
• Flies well.
• Online help videos.
MINUSES
• Wing
and was strapped in place with Velcro.
Some soft foam was used underneath
to prevent engine vibration, which
can froth the gasoline. The MSXR
comes with a template for the vendorrecommended
DLE engine. I used a
Mintor 33cc engine that had to be
manually aligned with the cowl. The
large, removable canopy top deck allows
easy access for the four engine bolts to
be inserted from behind the  rewall.
The stabilizers are held in place with
two short 3mm bolts apiece. Each wing
used one 5mm nylon bolt. The top deck
was held in place with two 3mm bolts,
and all of the radio parts were attached
with Velcro straps.
Wiring
There are some long wires to run
from the elevator servos to the middle
of the airplane. The manufacturer wisely
provided laser-cut guide holes in the
fuselage formers to keep the servo wires
away from the rudder pull-pull wires.
There is a plywood  oor in the wing/
cockpit area, allowing you to pass the
wiring under nearly all of the obstacles.
Telemetry
The Spektrum TM1000 module was
used to measure the engine temperature,
the receiver battery level, the ignition
battery level, and the engine’s rpm
in  ight. It was easy to bury this
extra wiring in the side chambers
of the fuselage’s plywood laser-box
construction.
A common misconception is that you
need to use a DX8 transmitter to obtain
telemetry information. Today, if you
have an iPhone you can use an optional
telemetry receiver module with any JR
DSM transmitter and a DSM receiver
that has a data port.
I hit a snag with the rpm sensor.
The current Spektrum rpm sensor is
designed to  t on the back of a smaller,
conventional glow engine. There was
nowhere practical to  t this onto a
Mintor 33c. Then it hit me—the Hall
Effect sensor that provided signals to the
ignition system could also provide signals
to the Spektrum telemetry module. All I
needed was a Y lead and a feed/tap from
the Mintor 33’s ignition sensor.
I created a new adapter lead from a
spare telemetry extension lead for the
rpm port of the telemetry module. Now,
the engine’s valuable rpm data could be
obtained when it was in the air.
Not only that, but you could now set
an rpm alarm to sound if the rpm value
went to zero during  ight. You would
know if your engine quit, even if other
engines were running at the time.
Radio
The biggest choice that the builder
has to make is which servos to use.
Choosing a strong servo is a good
idea when you intend to do strenuous
aerobatics. Because I was accustomed
to  ying large International Miniature
Aerobatic Club (IMAC) airplanes, my
initial thought was to use my JR 8711s.
However, these servos are both
heavy and expensive. I chose Spektrum
A6030s instead because they are capable
of giving 220 ounces of pulling power
and are $100 less than the JR 8711s.
They also weigh nearly 1/2 ounce less.
There is an old expression that
says you can’t add lightness, so the JR
8711s—as much as they are awesome—
would have been the wrong choice.
However, I put one on the rudder—just
for grins!
The selected transmitter was the JR
11X 2.4 GHz. This advanced radio is
ideal for a fully 3-D aerobatic model.
I decided to use three  ight modes.
You can name the  ight modes on
this radio so that you can see on the
computer display which mode you’re
about to use. I used the names “Smooth,”
“Normal,” and “3-D” to indicate small
throws, sport throws, and extreme
aerobatic high-alpha (3-D) throws. The
MSXR is a highly aerobatic airplane,
but it can easily be tamed with small
control throws and judicious use of
exponential.
Other options, such as linked elevators
and  aps, landing  aps, and high-alpha
control settings, are easily programmed
with this radio and can also be selected
with the  ight-mode switch. When
maximum throws are selected, a large
percentage of exponential is also dialed
in to make the airplane controllable near
the center stick positions.
An eight-channel Spektrum receiver
allowed use of the JR 11X dual-elevator
servo control option (Aux-3). A  aperon
wing con guration was also selected.
The TM1000 telemetry module was
included to measure the receiver battery
level and a second battery level. This
second battery function normally is used
on electric airplanes to measure the
All of the control surfaces use a double epoxy-board
horn to provide excellent rigidity to the pushrod,
transferring the forces from the servos.
Le : The nerve center of the MXSR contains a load of
telemetry, including receiver pack voltage, ignition
pack voltage, air speed, head temperature, and
altitude
electric motor  ight packs. I decided to
use the available circuit to measure the
voltage of the ignition system battery.
This allows you to read the status of
all of your batteries before you take off,
and you can set audible alarm levels to
tell you if there is a potential problem
while you are  ying. It
would be good to
be alerted if
your engine
is overheating. (I use the sensors to
monitor and test new engines, but they
could potentially prevent disaster.)
Flight Report
For the  rst test  ight, a heavier
aluminum spinner was  tted instead of
the lighter carbon- ber version, to bring
the CG forward slightly as a precaution.
Because of editorial deadlines and erratic
winter weather, the  rst  ight was made
after the Mintor 33cc was allowed to
run only for a few minutes.
It ran well with a 19 x 8 carbon- ber
Mejzlik propeller. I was con dent that
the motor would last for an entire  ight.
More importantly, it would reliably idle
for landing. The only change I made was
to adjust the throttle curve on the JR
11X, so the throttle stick advancement
gave a more linear increase in rpm.
It was a windy day, with gusts at 10
Top Dawg Aviation Mintor 33cc
The Mintor 33cc is a new engine
from Italy, imported by Top Dawg
Aviation. Its size and weight made
it an ideal candidate for the MSXR
review model.
RedwingRC sells a good DLE 30 for its
airplane. However, I had two new engines
to test for the “Engines” Column: one was
the O.S. 33GT, and the other was the
Mintor 33. The master plan for my MA
“Engines” column is to not just bench test,
but also to see how well engines do in the
air.
Then along came the MSXR. One
“connecting-the-dots” moment later, and
I concluded, “What better platform than
the 30-size MSXR?” The Mintor 33cc is
unusual because the main casing/barrel
and head, etc. are all machined from
aluminum bar stock. This leads to a light
engine for its class.
It has a semiautomatic choke. You
“lock” the choke in the on position with
a low-throttle setting. Then, when you
decide to open the throttle, the choke
lever is released and springs to the turnedoff
position.
This action was a minor problem
SPECIFICATIONS
Displacement: 33cc
Power: Approximately 4.2 horsepower,
with canister
Weight: 2.1 pounds
Bore: 1.55 inches
Stroke: 1.06 inches
Length: 6.37 inches (complete with
spacers)
RPM range: 1650 to 9500 rpm
Aircraft: Aerobatic with 68- to 80-inch
wingspan
Carburetor: Walbro
Recommended
propeller: Mejzlik 19 x 8 or 19 x 10
Included
electronic
ignition: 3.7 ounces
Included
muffl er: 2.04 ounces
Warranty: Three years
Price: $325
AT A GLANCE ...
for the  rst run. To get the fuel to the
carburetor for the  rst time, the choke
had to be manually held closed and the
throttle fully opened while the engine
was slowly hand-cranked. This method
got the gasoline mix to  ow into the
carburetor. After that, the throttle was
closed and the auto choke engaged.
Three  icks of the 19 x 8 carbon- ber
Mejzlik propeller later, the Mintor 33cc
spoke for itself. Opening and closing
the throttle from the radio released
the choke; two more  icks later, it was
running.
This Mintor 33 was perfect thereafter.
Right out of the box, it had an idle so
great that you could let the MSXR set
still on smooth blacktop with the engine
running.
There was no time to break the engine
in, so I adjusted the throttle curve to
pick up the rpms sooner on the low
end and made the action of the throttle
stick more linear. I did a taxi test to get
a feel for the tracking and the steering
power of the rudder. The engine was
still purring beautifully and it sounded
as though it was begging me to push the
stick forward.
The Mintor 33cc did not disappoint. I
kept it at roughly half throttle for most
of the early test- ight and the photoshoot
 ight. The engine never got too
hot and continued to idle like a Swiss
watch throughout the program. Later
 ights showed the vertical power was
also excellent.
—Eric Henderson
ehengineman.gmail.com
SOURCES:
Top Dawg Aviation
(832) 477-4842
www.topdawgaviation.com
The Mintor 33cc
is a “drop-in” on
the nose of the
MSXR. The only
part that sticks
out of the cowl is
the muffler pipe
to 20 mph. I did a taxi test to get a feel
for the tracking and the steering power
of the spring-loaded tail wheel setup,
which worked well with no nose-tipping
tendencies. With the Mintor still purring
beautifully, I had no excuses left, and the
audience of three told me to push the
throttle stick forward.
I set all of the rate switches to low,
( ight-mode “Smooth”), double-checked
the directions of the controls, turned on
the 10-minute countdown timer, and
pointed the airplane into the wind.
The takeoff run was made at half
throttle. The tail came up and tracked
dead straight. With a touch of upelevator,
we were quickly in the air
and  ying. Only a few beeps of downelevator
trim were needed.
This is one responsive airplane. The
wind off the end of the runway ridge
was nasty and had vicious sheers and
curls. However, I needed  ying shots,
so I pushed my luck  ying low and
slow. The wiser head of my conscripted
cameraman, Marv Napier (from my
District of Columbia Radio Control
Club), reminded me to conserve fuel for
the landing. I must admit that I did not
want to; I had found a sweet spot in the
air and was getting into some hovering
and high-alpha rolls.
Landing was an experience in its
own right. There were plenty of windgenerated
bumps and kicks, but always
an immediate response from the MXSR
to any of my  ight corrections. A high
“purr” idle was added for  nal approach
to keep up some airspeed. I lowered
the aircraft nearly level to the runway,
dragged the tail wheel, fought the
crosswind, and still got the wheels on
the runway.
On another day, with no wind, no
camera, and just me and my JR 11X, the
lightness was evident in all aspects of the
 ight. There is really only one word to
capture how the MXSR feels in the air:
nimble!
The rolls are easy and the rudder
is strong, even at low settings. More
adventurous and speci c maneuvers were
attempted next. A single-roll loop was
no problem. A knife-edge loop can be
tightened to a higher exit than entry. (I
always like having some rudder power
left for this maneuver.) Multiple highalpha
rolls in a straight line or a circle
were practical. The Spektrum servos were
fast and strong enough for the job.
The MXSR will do  at turns with
some aileron correction. A four-point roll
is easy with good rudder response. Eightpoint
and 16-point rolls are comfortable
with this airplane—just remember to
count them four at a time!
I noted that the stop/start roll
transitions were crisp, probably because
of the high torque of the aileron servos.
The high-alpha, half-throttle, taildragging-
style knife-edges will become
a party piece for those who love to do
them.
For the last landing, I used the air-brake
option (1/4-inch up on both ailerons).
This allows you to hold the nose up
slightly more. You could slow the MXSR
down and drag the tail wheels a long way
before actually touching down.
I was delighted by the  ying characteristics
of this aircraft.
Conclusion
At the time of this writing, the MSXR
is listed online for $379 without a
spinner or $399 with a matching painted
carbon- ber spinner. Considering that
you provide the engine, radio system,
and propeller, the MSXR is still good
value for the money because it is well
constructed and much of the work has
already been done for you. Add to that
its excellent  ying characteristics. The
MSXR allows you to easily hover and
3-D with a gas airplane that will  t into
your mid-size family car.
I have been exuberant about this
airplane since the beginning of the build,
but it is hard to hold back when you
like something this much. This airplane
deserves nothing but respect from me.
“Magnetos off.”
—Eric Henderson
[email protected]
MANUFACTURER/DISTRIBUTOR:
RedwingRC
(636) 600-8735
http://redwingrc.com/planes/30cc-mxsr-mxs-r.htm
SOURCES:
Mintor 33cc engine
(832) 477-4842
www.topdawgaviation.com
Spektrum
(800) 338-4639
www.spektrumrc.com
JR Radios
(800) 338-4639
www.jrradios.com

The new RedwingRC MXSR
aerobatic airplane is produced by
an owner who is an enthusiastic
RC pilot. RedwingRC can sell you the
kit and the extras (such as a DLE engine
and strong servos) that you need to
complete the airplane. The company
also sells all of the major parts you
might need down the road. Not sold
are the company’s excellent online
construction/help videos—they are free!
There is a growing market for .30-
size gas airplanes that you can  t into
today’s smaller cars. You get a Giant
Scale appearance and better vertical
performance because of the lightweight
nature of the beast.
The MXSR comes in red, blue, or
yellow, and has optional decals to go
with the optional painted CF spinner.
The kit is complete and features
removable stabilizers, carbon- ber wing,
tail tubes, landing gear, optional spinner,
and huge servo-arm extensions. The
control surfaces use  berglass board,
double-truss control horns. You also get
wheel pants pre tted with a T-nut and a
pre-plumbed tank. RedwingRC intends
to save you as much assembly time as
possible.
The pushrods are all (except for the
throttle) turnbuckle style, which means
that they have left- and right-hand
threads at opposite ends. The engine
cowl has a pre tted plywood ring with
T-nuts already installed, so it simply
bolts straight onto the front.
The fuselage is ready to accept
muf er canisters, so modi cations are
unnecessary. The horizontal stabilizers
are removable for transporting it in
medium-size cars. What you may not
see is that the wing-tube sleeve inside
the wing is also carbon  ber for added
strength. (For you electric power
enthusiasts, there is a hatch in the
underbelly behind the undercarriage for
easy battery insertion.)
Most notable is what is not in the
box. The MSXR is supported by the
aforementioned online construction
videos that are loaded with coaching/
construction guidance. The videos
can be found at the link listed under
“Manufacturer/Distributor.” These
videos will help you quickly and
The MXSR, shown in a half knife-edge, presents well
and maintains stable flight even in windy conditions.
successfully construct this airplane and
get it in the air.
The videos are so good that, in most
cases, you do not need the instructions.
They leave a reviewer with little to write
about. However, to give you an idea of
the actual work entailed to complete
an MXSR, this review has been broken
down into tasks. This article summarizes
the work that you need to do beyond
what is in the box.
Ironing and Cutting
The covering was good and only
a few small places required gentle
application of an iron to reshrink the
material. You have to make a decision
about the orientation of the aileron
servos. You can have them lie  at or be
vertically mounted. This determines
whether you cut a hole in the wing or
you expose a hatch plate. You also need
to look for the hole to open up for the
elevator servos and the pull-pull wire
exits.
When you need to choose where your
switches will go, you will  nd existing
sites under the covering next to where
the fuel line dot goes. These have all been
laser cut in advance.
Gluing
Glue the hinges for the stabilizer, the
rudder, and the ailerons. You should apply
a small amount of oil to the hinge pivot
point to make sure the hinges do not stick
to the epoxy. You also need to glue in the
dual control horns. The two-horn setup
is made of epoxy board. The horns are
epoxied into each control. The laser-cut
plywood mounting plate/cradle for the
throttle servo is glued in place after the
“run” for the throttle pushrod has been
established.
Drilling
It is a good idea to predrill the servo
screw mounting holes to avoid splitting
the wood. You will also drill four holes
for the engine mount standoffs. There
can be some grinding or drilling required
when you cut any holes in the cowl. The
Mintor 33cc only needed an exit hole for
the exhaust pipe. No hole was needed
for the spark plug. Adding a small hole,
allowing long screwdriver access to the
carburetor adjustment screws, is also a
good idea. Otherwise, the cowl stayed
intact.
The MXSR comes with a carbon-
 ber undercarriage and preassembled
wheel pants. It only took two screws to
attach each wheel pant. I ground out
the clearance for the wheel tires because
front tires tend to expand when spinning
fast and can sometimes catch the wheel
pants. The drilling is done!
Screws and Bolts
Connect all of the control surfaces
with turnbuckle pushrods. These allow
for large or small trimming when
adjusting the control surfaces. Because
there is a left-hand thread and a righthand
thread on each pushrod, you can
be precise with your changes.
One tip is to use a slow electric drill
to pre-run both the right-hand and lefthand
threads into each plastic clevise
at least once. This will make manual
adjustment easier when the rods are
installed between the servo arm and the
control horn.
The fuel tank came preassembled
All of the major pieces
are pre nished. The
cowl, canopy, and
stabilizers all attach
with 3mm bolts. The
wings use a carbon-
 ber tube and
two threaded
nylon bolts to
become part of the
completed MXSR.
SPECIFICATIONS
Model type: Aerobatic
Wingspan: 76 inches
Length: 70 inches (spinner to tail)
Wing area: 1,100 square inches
Weight: 10.75 to 11.25 pounds
Construction: Carbon-fi ber wing tube, tail
tube, landing gear, tail gear,
and spinner
Price: $379 without spinner;
$399 with spinner
Covering/fi nish: UltraCote
TEST-MODEL DETAILS
Weight: 11 pounds, 4.25 ounces
(including radio equipment,
telemetry overhead, and
engine, but no fuel)
Center of gravity: Set at 127mm for initial fl ight
Radio system: Spektrum A6030 x 4,
JR 537 (throttle), JR8711
(rudder) servos; AR8000
receiver; JR 11X transmitter
Motor: Mintor 33cc
Propeller: Mejzlik 19 x 8 with aluminum
spinner
Receiver battery: 2600 mAh 2S 8.4-volt LiPo
with Turnigy BEC 5.2-volt
switching regulator
Ignition battery: 1500 mAh 2S 8.4-volt LiPo
with Turnigy BRC 5.2-volt
switching regulator
PLUSES
• Ease of build.
• Lightweight construction.
• Flies well.
• Online help videos.
MINUSES
• Wing
and was strapped in place with Velcro.
Some soft foam was used underneath
to prevent engine vibration, which
can froth the gasoline. The MSXR
comes with a template for the vendorrecommended
DLE engine. I used a
Mintor 33cc engine that had to be
manually aligned with the cowl. The
large, removable canopy top deck allows
easy access for the four engine bolts to
be inserted from behind the  rewall.
The stabilizers are held in place with
two short 3mm bolts apiece. Each wing
used one 5mm nylon bolt. The top deck
was held in place with two 3mm bolts,
and all of the radio parts were attached
with Velcro straps.
Wiring
There are some long wires to run
from the elevator servos to the middle
of the airplane. The manufacturer wisely
provided laser-cut guide holes in the
fuselage formers to keep the servo wires
away from the rudder pull-pull wires.
There is a plywood  oor in the wing/
cockpit area, allowing you to pass the
wiring under nearly all of the obstacles.
Telemetry
The Spektrum TM1000 module was
used to measure the engine temperature,
the receiver battery level, the ignition
battery level, and the engine’s rpm
in  ight. It was easy to bury this
extra wiring in the side chambers
of the fuselage’s plywood laser-box
construction.
A common misconception is that you
need to use a DX8 transmitter to obtain
telemetry information. Today, if you
have an iPhone you can use an optional
telemetry receiver module with any JR
DSM transmitter and a DSM receiver
that has a data port.
I hit a snag with the rpm sensor.
The current Spektrum rpm sensor is
designed to  t on the back of a smaller,
conventional glow engine. There was
nowhere practical to  t this onto a
Mintor 33c. Then it hit me—the Hall
Effect sensor that provided signals to the
ignition system could also provide signals
to the Spektrum telemetry module. All I
needed was a Y lead and a feed/tap from
the Mintor 33’s ignition sensor.
I created a new adapter lead from a
spare telemetry extension lead for the
rpm port of the telemetry module. Now,
the engine’s valuable rpm data could be
obtained when it was in the air.
Not only that, but you could now set
an rpm alarm to sound if the rpm value
went to zero during  ight. You would
know if your engine quit, even if other
engines were running at the time.
Radio
The biggest choice that the builder
has to make is which servos to use.
Choosing a strong servo is a good
idea when you intend to do strenuous
aerobatics. Because I was accustomed
to  ying large International Miniature
Aerobatic Club (IMAC) airplanes, my
initial thought was to use my JR 8711s.
However, these servos are both
heavy and expensive. I chose Spektrum
A6030s instead because they are capable
of giving 220 ounces of pulling power
and are $100 less than the JR 8711s.
They also weigh nearly 1/2 ounce less.
There is an old expression that
says you can’t add lightness, so the JR
8711s—as much as they are awesome—
would have been the wrong choice.
However, I put one on the rudder—just
for grins!
The selected transmitter was the JR
11X 2.4 GHz. This advanced radio is
ideal for a fully 3-D aerobatic model.
I decided to use three  ight modes.
You can name the  ight modes on
this radio so that you can see on the
computer display which mode you’re
about to use. I used the names “Smooth,”
“Normal,” and “3-D” to indicate small
throws, sport throws, and extreme
aerobatic high-alpha (3-D) throws. The
MSXR is a highly aerobatic airplane,
but it can easily be tamed with small
control throws and judicious use of
exponential.
Other options, such as linked elevators
and  aps, landing  aps, and high-alpha
control settings, are easily programmed
with this radio and can also be selected
with the  ight-mode switch. When
maximum throws are selected, a large
percentage of exponential is also dialed
in to make the airplane controllable near
the center stick positions.
An eight-channel Spektrum receiver
allowed use of the JR 11X dual-elevator
servo control option (Aux-3). A  aperon
wing con guration was also selected.
The TM1000 telemetry module was
included to measure the receiver battery
level and a second battery level. This
second battery function normally is used
on electric airplanes to measure the
All of the control surfaces use a double epoxy-board
horn to provide excellent rigidity to the pushrod,
transferring the forces from the servos.
Le : The nerve center of the MXSR contains a load of
telemetry, including receiver pack voltage, ignition
pack voltage, air speed, head temperature, and
altitude
electric motor  ight packs. I decided to
use the available circuit to measure the
voltage of the ignition system battery.
This allows you to read the status of
all of your batteries before you take off,
and you can set audible alarm levels to
tell you if there is a potential problem
while you are  ying. It
would be good to
be alerted if
your engine
is overheating. (I use the sensors to
monitor and test new engines, but they
could potentially prevent disaster.)
Flight Report
For the  rst test  ight, a heavier
aluminum spinner was  tted instead of
the lighter carbon- ber version, to bring
the CG forward slightly as a precaution.
Because of editorial deadlines and erratic
winter weather, the  rst  ight was made
after the Mintor 33cc was allowed to
run only for a few minutes.
It ran well with a 19 x 8 carbon- ber
Mejzlik propeller. I was con dent that
the motor would last for an entire  ight.
More importantly, it would reliably idle
for landing. The only change I made was
to adjust the throttle curve on the JR
11X, so the throttle stick advancement
gave a more linear increase in rpm.
It was a windy day, with gusts at 10
Top Dawg Aviation Mintor 33cc
The Mintor 33cc is a new engine
from Italy, imported by Top Dawg
Aviation. Its size and weight made
it an ideal candidate for the MSXR
review model.
RedwingRC sells a good DLE 30 for its
airplane. However, I had two new engines
to test for the “Engines” Column: one was
the O.S. 33GT, and the other was the
Mintor 33. The master plan for my MA
“Engines” column is to not just bench test,
but also to see how well engines do in the
air.
Then along came the MSXR. One
“connecting-the-dots” moment later, and
I concluded, “What better platform than
the 30-size MSXR?” The Mintor 33cc is
unusual because the main casing/barrel
and head, etc. are all machined from
aluminum bar stock. This leads to a light
engine for its class.
It has a semiautomatic choke. You
“lock” the choke in the on position with
a low-throttle setting. Then, when you
decide to open the throttle, the choke
lever is released and springs to the turnedoff
position.
This action was a minor problem
SPECIFICATIONS
Displacement: 33cc
Power: Approximately 4.2 horsepower,
with canister
Weight: 2.1 pounds
Bore: 1.55 inches
Stroke: 1.06 inches
Length: 6.37 inches (complete with
spacers)
RPM range: 1650 to 9500 rpm
Aircraft: Aerobatic with 68- to 80-inch
wingspan
Carburetor: Walbro
Recommended
propeller: Mejzlik 19 x 8 or 19 x 10
Included
electronic
ignition: 3.7 ounces
Included
muffl er: 2.04 ounces
Warranty: Three years
Price: $325
AT A GLANCE ...
for the  rst run. To get the fuel to the
carburetor for the  rst time, the choke
had to be manually held closed and the
throttle fully opened while the engine
was slowly hand-cranked. This method
got the gasoline mix to  ow into the
carburetor. After that, the throttle was
closed and the auto choke engaged.
Three  icks of the 19 x 8 carbon- ber
Mejzlik propeller later, the Mintor 33cc
spoke for itself. Opening and closing
the throttle from the radio released
the choke; two more  icks later, it was
running.
This Mintor 33 was perfect thereafter.
Right out of the box, it had an idle so
great that you could let the MSXR set
still on smooth blacktop with the engine
running.
There was no time to break the engine
in, so I adjusted the throttle curve to
pick up the rpms sooner on the low
end and made the action of the throttle
stick more linear. I did a taxi test to get
a feel for the tracking and the steering
power of the rudder. The engine was
still purring beautifully and it sounded
as though it was begging me to push the
stick forward.
The Mintor 33cc did not disappoint. I
kept it at roughly half throttle for most
of the early test- ight and the photoshoot
 ight. The engine never got too
hot and continued to idle like a Swiss
watch throughout the program. Later
 ights showed the vertical power was
also excellent.
—Eric Henderson
ehengineman.gmail.com
SOURCES:
Top Dawg Aviation
(832) 477-4842
www.topdawgaviation.com
The Mintor 33cc
is a “drop-in” on
the nose of the
MSXR. The only
part that sticks
out of the cowl is
the muffler pipe
to 20 mph. I did a taxi test to get a feel
for the tracking and the steering power
of the spring-loaded tail wheel setup,
which worked well with no nose-tipping
tendencies. With the Mintor still purring
beautifully, I had no excuses left, and the
audience of three told me to push the
throttle stick forward.
I set all of the rate switches to low,
( ight-mode “Smooth”), double-checked
the directions of the controls, turned on
the 10-minute countdown timer, and
pointed the airplane into the wind.
The takeoff run was made at half
throttle. The tail came up and tracked
dead straight. With a touch of upelevator,
we were quickly in the air
and  ying. Only a few beeps of downelevator
trim were needed.
This is one responsive airplane. The
wind off the end of the runway ridge
was nasty and had vicious sheers and
curls. However, I needed  ying shots,
so I pushed my luck  ying low and
slow. The wiser head of my conscripted
cameraman, Marv Napier (from my
District of Columbia Radio Control
Club), reminded me to conserve fuel for
the landing. I must admit that I did not
want to; I had found a sweet spot in the
air and was getting into some hovering
and high-alpha rolls.
Landing was an experience in its
own right. There were plenty of windgenerated
bumps and kicks, but always
an immediate response from the MXSR
to any of my  ight corrections. A high
“purr” idle was added for  nal approach
to keep up some airspeed. I lowered
the aircraft nearly level to the runway,
dragged the tail wheel, fought the
crosswind, and still got the wheels on
the runway.
On another day, with no wind, no
camera, and just me and my JR 11X, the
lightness was evident in all aspects of the
 ight. There is really only one word to
capture how the MXSR feels in the air:
nimble!
The rolls are easy and the rudder
is strong, even at low settings. More
adventurous and speci c maneuvers were
attempted next. A single-roll loop was
no problem. A knife-edge loop can be
tightened to a higher exit than entry. (I
always like having some rudder power
left for this maneuver.) Multiple highalpha
rolls in a straight line or a circle
were practical. The Spektrum servos were
fast and strong enough for the job.
The MXSR will do  at turns with
some aileron correction. A four-point roll
is easy with good rudder response. Eightpoint
and 16-point rolls are comfortable
with this airplane—just remember to
count them four at a time!
I noted that the stop/start roll
transitions were crisp, probably because
of the high torque of the aileron servos.
The high-alpha, half-throttle, taildragging-
style knife-edges will become
a party piece for those who love to do
them.
For the last landing, I used the air-brake
option (1/4-inch up on both ailerons).
This allows you to hold the nose up
slightly more. You could slow the MXSR
down and drag the tail wheels a long way
before actually touching down.
I was delighted by the  ying characteristics
of this aircraft.
Conclusion
At the time of this writing, the MSXR
is listed online for $379 without a
spinner or $399 with a matching painted
carbon- ber spinner. Considering that
you provide the engine, radio system,
and propeller, the MSXR is still good
value for the money because it is well
constructed and much of the work has
already been done for you. Add to that
its excellent  ying characteristics. The
MSXR allows you to easily hover and
3-D with a gas airplane that will  t into
your mid-size family car.
I have been exuberant about this
airplane since the beginning of the build,
but it is hard to hold back when you
like something this much. This airplane
deserves nothing but respect from me.
“Magnetos off.”
—Eric Henderson
[email protected]
MANUFACTURER/DISTRIBUTOR:
RedwingRC
(636) 600-8735
http://redwingrc.com/planes/30cc-mxsr-mxs-r.htm
SOURCES:
Mintor 33cc engine
(832) 477-4842
www.topdawgaviation.com
Spektrum
(800) 338-4639
www.spektrumrc.com
JR Radios
(800) 338-4639
www.jrradios.com