Power Switch: JR 12X 2.4 GHz RC System - 2009/03

FOR MANY YEARS, JR has had
one of the best advanced radiocontrol
systems: its sophisticated
10X transmitter and various
matching 10-channel Pulse Code
Modulation (PCM) receivers. The
combination has proven
itself to be a reliable
competition and scale
performer.
Remember that
regardless of what the
hype might be, no
competitive pilot will
use an RC system that
cannot perform.
Thousands of
competitive pilots who
regularly experience
tense competitive
situations rely on
their 10Xs.
As good as the
10X is, it has two
shortcomings. First,
Scale pilots can
always use more channels as their superb models get ever more
complicated. Ten channels doesn’t seem enough somehow.
The 10X’s second weakness is that it is unavailable in a 2.4
GHz system. Every RC pilot probably knows about 2.4 GHz by
now, but a quick review is in order.
A “2.4 GHz” designation means that the radio system
transmits digitally on the 2.4 GHz bandwidth instead of the 72
MHz space. Because of the way FCC regulations are set, it is
extremely difficult for one 2.4 GHz system to interfere with
another. JR goes even further to prevent interference by randomly
selecting two frequency bands (called “DuaLink”) within the 2.4
GHz space for each flight.
If you have spent $5,000 for an RC
Aerobatics (Pattern) model, $15,000
for a jet, $10,000 for an International
Miniature Aerobatic Club (IMAC)
aircraft, you have invested 1,000 hours in
a Scale masterpiece, having such “shootdown”
protection is comforting. Even
noncompetition pilots need
2.4 GHz.
Enter the 12X: Operating
on 2.4 GHz has several other
advantages, including speed
and digital precision. Both
are vital for competition
pilots.
JR could have
converted its excellent 10X
to 2.4 GHz by changing
the transmitter module.
Instead, the company
developed a new system
with more channels, greater flexibility,
and easier programming.
Before looking at the 12X in detail, I need to
explain that this study is not the typical technical
review with exploded photos of disassembled parts. If you need
to know what size bearings are used for the four that support each
12X transmitter stick, call JR technical service (which has helped
me more than once). Working a JR 12X control stick is like
gliding in calm air—it’s smooth and precise—because each stick
is supported so well.
The sophisticated 12X DSM2 radio system is designed for the
advanced modeler. It can be ordered as either a 2.4 GHz-only
system, which is compatible with all Spektrum and JR 2.4 GHz
receivers (even the first AR6000), or a selectable 2.4 GHz/72
MHz system: the JR12X MV.
The 12X has a 50-model memory, but it will accept unlimited
model memories from your computer (50 at a time). The JR radio also has
ModelMatch: a system that permits the aircraft to respond only if that exact
receiver/aircraft is the one selected on the transmitter.
The entire system is optimized for airplane, helicopter, and soaring
operation, and each category has its own programming features. The 12X is
the only transmitter a pilot will ever need.
It also has triple rate/exponential switches, double flight battery inputs, a
receiver that can handle up to 35 amps of current, and the most
sophisticated and easy-to-use programming capabilities designed for today’s
+
• Easy to program and understand.
• 2048 resolution and fast response
on all channels.
• All mixes summarized on one
page.
• All possible programs listed on
just two pages.
• Five flight modes and triple rates.
• Knife-edge trimming and twinengine
mixing.
• Synchronizes servos with no extra
equipment.
• Two receiver battery inputs.
• Four separate receivers maximizes
transmitter/receiver bond.
• Includes great application booklet.
• Manual throttle trim lever
provides easy in-flight adjustment
for high-trim aerobatics, medium
trim for approaches, and engine
shutoff (low) on one lever. -• No throttle ratchets (indents).
• Including a JR Flight Log would
have been a big plus.
complex Scale, competition, and
advanced sport aircraft. There are
two fail-safe systems, five flight
modes, and dual snap-roll switches
that are ideally placed, allowing the
pilot to keep both hands on the sticks
while pushing “da button” (finally!).
Although these features are great, there
must be more to the 12X than the
“prestige” of flying with a top-of-the-line
radio system. Since no amount of prestige
will move even one aileron, the 12X had
better perform. And it does!
First, the 2.4 GHz 12X is much faster
than a PCM system. In the latter, several
68 MODEL AVIATION
Right: Two instruction guides are
included. JR provides a concise, stepby-
step guide for setting up a complex
aerobatic model, a competition
helicopter, and what appears to be an
advanced sailplane.
JR sells several neck-strap adjusters
separately to match the included neck
strap. The adjusters (item SPM6703) keep
the transmitter balanced and level, despite
the short antenna.
Left: Both instructional guides
include detailed instructions,
definitions, and screen shots of most
programming steps.
The 12X is capable of complex programming required for a competition Pattern model
such as the Prestige (R). Hangar 9’s P-47 (L) not only needs aerobatic trim programming,
but also requires 11 channels to eliminate roll coupling, stop adverse yaw, light the glow
plug, and coordinate flaps.
Modulation: 2.4 GHz
Weight: 1.3 ounces (total)
Current drain: 70 mA (including
signal)
Size: 1.48 x 2.1 x .628 inches (main)
Antenna length(s): Approximately
2 inches
Intention: Full range
JR R1221 DSM2 Receiver Specifications
analog-to-digital transformations must
occur, which takes time. The 12X
transmits in digital, eliminating the
translation phases. The time between
stick movement and servo response is
called the “latency period,” and the
12X’s is extremely short (referred to as
“low” for some reason).
Many pilots may think that the
response-speed increase will go
unnoticed. But advanced servos are so
fast (.06-.15 second) that any latency is
noticeable, even when flying a trainer.
Second, the 12X has a resolution of
2048; that’s 2,048 discrete servomovement
positions in the 60° arc of the
servo output arm. This translates into
extreme precision and ultimate aircraft
control.
Most sport 2.4 GHz radios are 1024
systems—half as exact as the 12X. The
high resolution becomes apparent while
flying any sport aerobatic airplane, but
precision machines such as those in
IMAC competition and Pattern and F3C
and 3-D helicopters literally revel in it.
To best utilize the 2048 resolution,
Type: Pro-level computer
Skill level: Advanced pilots
Number of proportional
channels: 12
Safety features: ModelMatch,
Smart Safe for electrics; fail-safe
(two)
Model memory: 50 plus computer
storage
Frequency: 2.4-2.483 GHz
Modulation: Direct spread spectrum
(DSM2/DSM1) plus DuaLink
Channel resolution: 2048
Power supply: 9.6-volt, 2000 mAh
NiMH battery
Current drain: 180 mA DSM2 or
280 mA DSM1
Temperature range: 30° (screen
disappears)
Trim type: Analog, throttle; all
others, digital
Gimbal type: Four ball bearings,
adjustable stick tension
View screen: 4.25 x 1.3 inches,
backlit
Program input: Roller/push button
with switches
Trainer function: Fully
programmable
Number of switches: 18
Number of sliders: One (throttle
trim)
Transmitter battery: 2000 mAh
NiMH
Included: JR R1221 DSM2 receiver,
aluminum transmitter case
Programming features: Aircraft,
helicopter, sailplane
Street price: $1,499
JR 12X General Specifications
03sig3.QXD 1/26/09 12:45 PM Page 68
March 2009 69
Airplane Standard: Servo reverse, travel adjust, exponential, subtrim, throttle hold, throttle curve, servo speed, snap roll,
aileron differential, aileron-to-rudder mix, elevator-to-flap mix, flap-to-elevator mix (flap system), eight programmable mixes
(five curved), flaperon, V-tail and elevon mixing
Airplane Advanced: Servo balance, triple rates (aileron/elevator/rudder), knife-edge mix, five flight modes, twin-engine mix,
control stick as mix switch, pitch curve (adjustable propellers), aileron-to-flap mix, internal model memory backup copy
system, etc. (See text.)
Helicopter Program Features: Six swashplate types (normal, two-servo 180°, three-servo 120°, three-servo 140°, threeservo
90°, four-servo 90°); programmable trainer system (selectable channels for student control); gyro sensor; servo speed;
governor; tail curve; dual pitch; swashplate mix; pitch curve; eight programmable mixes; built-in cyclic-to-throttle mixing for
aileron, elevator, rudder; electronic 3-D cyclic ring to prevent overdriving cyclic servos with combined aileron and elevator
commands; programmable servo speed
Sailplane Program Features: Ability to assign switches for channels and functions, rudder-to-spoiler mix, aileron-torudder
mix, flap rate, brake system, eight program mixes (five curved), trim system adjustment, as many as five fully
programmable flight modes that can be named, tip aileron programming, fully programmable motor function, camber
programming for each flight mode, servo monitor (automatically renames channels according to assignments), warning system
that allows alarms to be custom programmed for various switch and stick positions MA
—Frank Granelli
JR12X Notable Features
you must employ digital servos because
they are more exact than analog servos. All
12 of the channels are 2048 resolution and
are equally fast and proportional.
There is no closer bond between pilot
and model than when using a 2048, lowlatency,
2.4 GHz system such as the 12X.
The pilot’s “feel” is amazing and the
feedback is immediate. Control
improvement is so stunning that most
competition pilots (I am included) must
add several extra exponential points until
they become accustomed to the enhanced
control.
Of particular note is the much faster,
more controllable throttle response. Stall
turns and snap rolls suddenly become
much easier to time correctly.
Third, the 12X is the ultimate in
programming simplicity. As with all JR
systems, there are two programming
stages: System and Function modes. The
former covers all operations that usually
need to be set only once, including
selecting an aircraft, determining its type
(airplane, helicopter, or glider), naming it,
setting the wing type, setting switch
responsibilities, etc.
When System Mode is selected, all the
paradigms appear at once on the screen;
there is no paging and scrolling to find the
right subject. Just roll the button until the
proper function is highlighted and then
press the same rolling button. This not
only saves time, but it also makes
programming so easy that the pilot might
want to experiment.
The same is true for Function Mode;
press the “LIST” button and all the settings
appear on one page. Those are things we
change frequently, such as knife-edge trim
(the 12X has a programming page just for
setting rudder-elevator/aileron mixes for
straight and trimmed knife edges), subtrim,
exponential, aileron-rudder mixing, stepmixing,
regular programmable mixing, and
many more. Just roll, highlight, and push
the button.
As difficult to explain how easy this
transmitter is to program is how true it is.
And on the topic of programming, many
features are unique to the 12X. Following
are several of them.
• The knife-edge trim page mixes rudder to
both aileron and elevator in one mix.
• Dual elevator servos can be mixed from a
single page, including in-flight trim
changes.
• The 12X has a form of servo matching:
the Balance function mixed with the servo
speed adjuster, which matches servo
movement and speed so that multiple
servos moving a single control surface
function identically.
• The Balance function, a curve mix, also
adjusts for separate elevator half
geometries, assuring equal and matching
elevator response.
• The main control sticks can be used as
mixing on/off switches. This is useful for
smoke-system setups and more.
• The 12X has five curve mixes and five
Flight Modes—not just three of each.
Why do you need five Flight Modes?
you might ask. Aren’t the three available
in most near-high-end radio systems
enough? Yes, sometimes, but more may be
required in competition.
My Prestige, a competition Pattern
model, flies well in calm air using a threeblade
propeller but uses a two-blade in
heavy crosswind competition. As the
three-blade produces extra torque, it
requires a certain amount of elevator trim
and either proverse or adverse aileron
input for straight knife-edge flight and
vertical climbs. The two-blade propeller
requires a different trim setting for these
maneuvers—without aileron mixing.
Flight Modes are really different
program settings for the same airplane.
Simply flipping the switch puts a model in
the trim setting that is best suited to
changing flight or equipment conditions.
FM-1 is for the three-blade and FM-2 is
for windy weather with a two-blade
propeller.
The Prestige requires more elevator
input for inverted snap rolls than it can use
to fly Pattern. For that maneuver, I
normally use the Snap Roll button.
Since it is best to snap away from the
flightline, two more Flight Modes,
programmed with opposite outside snaproll
directions, are needed to suit either left
or right Pattern entries with the selected
propeller. That is four Flight Modes total.
A sport or IMAC competition airplane
may need FM-1 for normal flying, FM-2
for 3-D work, and FM-3 for Freestyle
control settings. Scale airplanes can use
one Flight Mode for normal flying, another
trimmed and set for the slow pass with
everything hanging out, and a third, even a
fourth, when imitating full-scale flight
(e.g., lower max power settings and slightly
reflexed ailerons to keep that Jenny from
climbing and turning like it’s an F-22).
Flipping a switch can convert your
airplane into five different models. If your
current transmitter has Flight Modes and
you don’t use them, you are missing a
great deal of what the system has to offer.
If you still don’t use them after reading
this, shame on me for not convincing you
to give them a try. The 12X’s Flight Mode
system is almost the most versatile and
easy to program I have flown.
The 12X is imperfect in just one respect; it
03sig3.QXD 1/26/09 12:48 PM Page 69
is available only without the usual throttlestick
indentations (“throttle clicks”).
According to JR, that was a request from its
helicopter and Scale Aerobatics team pilots.
I can’t argue with the company’s
champion fliers, but us lesser pilots could
use some throttle detents to help keep
power levels constant during rudderintensive
slow and point rolls. Fortunately
for us “normal” humans, JR will install
throttle detents free for any pilot who wants
them. That is the only 12X “feature” I
found to be difficult.
However, the 12X has so many good
features that it is senseless to worry about
throttle-stick detents. There are so many
features that it is impossible to list them all,
but I do have some favorites.
All trim screens have a throttle and/or
servo “hold” setting that makes safe
throttle-based trim changes possible while
the power system is operating. This is
especially useful when making those two
dozen landings while trying to trim knife
edges or vertical climbs.
The knife-edge mix (rudder-toelevator/
aileron mix) can be switched by the
throttle stick so that the trim settings
operate during flight but are inhibited
during stall turns and landings. The typical
down-elevator required for knife edge can
ruin a stall turn’s pitch and cause trim
problems during landing. The 12X
eliminates this problem. All the mixes can
be switched by the transmitter-stick
position, making for a seemingly infinite
variety of mix-to-mix settings.
The amount of aileron differential
needed for axial roll performance varies
with throttle settings and airspeed. The 12X
will use the throttle-stick position to alter
the programmed aileron differential rate so
that it is more pronounced at low throttle
settings as adverse yaw effects increase
with decreasing airspeed.
The twin-engine setting ensures that
both power plants operate at the same rpm
throughout the throttle range. The normal
twin yaw effects disappear, and only one
mix setting is required instead of multiple
mixing.
The customary throttle trim lever can
control either both engines simultaneously
or each engine can have independent trim
levers. This is useful for practicing singleengine
flying.
The 12X has two trim settings. The
normal one functions like almost all trim
levers do; it moves the center point and the
endpoint. The amount of movement can be
adjusted from four points per beep, coarse
trim, down to one point per beep for extrafine
trim adjustments.
Although the second LST (Limited
Standard Trim) function is also adjustable,
the trim button controls only the center
point. This prevents overdriving and
damaging servos at the endpoints. The
digital trim settings can apply to one Flight
Mode or can be made common to all Flight
Modes.
When used as a “master” in a buddy-box
system, the student can be assigned one or
more control functions, which the instructor
determines. The student can start with
aileron and elevator control only and then
move up to throttle and/or rudder as skills
improve.
The Dual Channel function allows all
control surfaces to be powered by separate
servos while remaining responsive to the
single digital trim buttons. This is a great
feature when using independent elevator
halves or ailerons.
The 12X has digital button trims on the
flight control surfaces but a trim lever on
the throttle. This eliminates the need for a
separate engine kill switch and allows the
pilot to determine and set the engine idle
rpm by feel during flight.
Two switchable aileron differential
settings are available per the Flight Mode.
The elevator-to-flap mix allows for
reflexing the ailerons for 3-D maneuvers
such as the Harrier and the Wall.
The flap-to-elevator system not only
compensates for pitch changes that flap
deployment causes, but the compensation
can be timed in 0.1-second intervals so that
both surfaces move at the same speed,
maintaining perfect trim during flap
deployment or retraction. The Auto Land
feature does this automatically.
The 12X has a mix monitor that displays
all programmed mixes, dual channels,
selected switches, and control surfaces so
that the pilot can determine the aircraft’s
setup with one glance. This radio system
includes software and connection hardware
so that it can copy programs to and from
another 12X or your computer.
The included JR R1221 receiver is
actually four receivers. The main unit has
three satellite receivers that mount remotely
9, 12, and 24 inches from the main receiver
to ensure the strongest possible reception in
all flight attitudes. The R1221 has full 2048
resolution plus dual flight-battery inputs for
greater safety.
This report has probably missed a dozen
important 12X capabilities. The system
arrives with the usual detailed instruction
book, but it also has an Applications and
Programming Guide. This step-by-step
manual goes through, in detail, the setup
and programming of a complex Giant Scale
IMAC airplane, a competition helicopter,
and a complex sailplane.
The sailplane guide covers such details
as Cruise Mode, camber adjustments,
airborne braking systems, launch and
landing modes, and much more that Soaring
pilots will love. The helicopter guide
includes setting up swashplate mixing,
cyclic mixes, throttle and pitch curves,
throttle holds, and other important trimming
operations. Jet pilots will love the extra
flight modes and the “stick as switch”
options.
Advanced radio studies traditionally end
with the phrase “this radio can grow with
the pilot.” The JR 12X leads the pilot to
that growth. MA
Frank Granelli
[email protected]
Sources:
Horizon Hobby Distributors
(800) 338-4639
www.jrradios.com
Other Printed Reviews:
Model Airplane News: November 2008

FOR MANY YEARS, JR has had
one of the best advanced radiocontrol
systems: its sophisticated
10X transmitter and various
matching 10-channel Pulse Code
Modulation (PCM) receivers. The
combination has proven
itself to be a reliable
competition and scale
performer.
Remember that
regardless of what the
hype might be, no
competitive pilot will
use an RC system that
cannot perform.
Thousands of
competitive pilots who
regularly experience
tense competitive
situations rely on
their 10Xs.
As good as the
10X is, it has two
shortcomings. First,
Scale pilots can
always use more channels as their superb models get ever more
complicated. Ten channels doesn’t seem enough somehow.
The 10X’s second weakness is that it is unavailable in a 2.4
GHz system. Every RC pilot probably knows about 2.4 GHz by
now, but a quick review is in order.
A “2.4 GHz” designation means that the radio system
transmits digitally on the 2.4 GHz bandwidth instead of the 72
MHz space. Because of the way FCC regulations are set, it is
extremely difficult for one 2.4 GHz system to interfere with
another. JR goes even further to prevent interference by randomly
selecting two frequency bands (called “DuaLink”) within the 2.4
GHz space for each flight.
If you have spent $5,000 for an RC
Aerobatics (Pattern) model, $15,000
for a jet, $10,000 for an International
Miniature Aerobatic Club (IMAC)
aircraft, you have invested 1,000 hours in
a Scale masterpiece, having such “shootdown”
protection is comforting. Even
noncompetition pilots need
2.4 GHz.
Enter the 12X: Operating
on 2.4 GHz has several other
advantages, including speed
and digital precision. Both
are vital for competition
pilots.
JR could have
converted its excellent 10X
to 2.4 GHz by changing
the transmitter module.
Instead, the company
developed a new system
with more channels, greater flexibility,
and easier programming.
Before looking at the 12X in detail, I need to
explain that this study is not the typical technical
review with exploded photos of disassembled parts. If you need
to know what size bearings are used for the four that support each
12X transmitter stick, call JR technical service (which has helped
me more than once). Working a JR 12X control stick is like
gliding in calm air—it’s smooth and precise—because each stick
is supported so well.
The sophisticated 12X DSM2 radio system is designed for the
advanced modeler. It can be ordered as either a 2.4 GHz-only
system, which is compatible with all Spektrum and JR 2.4 GHz
receivers (even the first AR6000), or a selectable 2.4 GHz/72
MHz system: the JR12X MV.
The 12X has a 50-model memory, but it will accept unlimited
model memories from your computer (50 at a time). The JR radio also has
ModelMatch: a system that permits the aircraft to respond only if that exact
receiver/aircraft is the one selected on the transmitter.
The entire system is optimized for airplane, helicopter, and soaring
operation, and each category has its own programming features. The 12X is
the only transmitter a pilot will ever need.
It also has triple rate/exponential switches, double flight battery inputs, a
receiver that can handle up to 35 amps of current, and the most
sophisticated and easy-to-use programming capabilities designed for today’s
+
• Easy to program and understand.
• 2048 resolution and fast response
on all channels.
• All mixes summarized on one
page.
• All possible programs listed on
just two pages.
• Five flight modes and triple rates.
• Knife-edge trimming and twinengine
mixing.
• Synchronizes servos with no extra
equipment.
• Two receiver battery inputs.
• Four separate receivers maximizes
transmitter/receiver bond.
• Includes great application booklet.
• Manual throttle trim lever
provides easy in-flight adjustment
for high-trim aerobatics, medium
trim for approaches, and engine
shutoff (low) on one lever. -• No throttle ratchets (indents).
• Including a JR Flight Log would
have been a big plus.
complex Scale, competition, and
advanced sport aircraft. There are
two fail-safe systems, five flight
modes, and dual snap-roll switches
that are ideally placed, allowing the
pilot to keep both hands on the sticks
while pushing “da button” (finally!).
Although these features are great, there
must be more to the 12X than the
“prestige” of flying with a top-of-the-line
radio system. Since no amount of prestige
will move even one aileron, the 12X had
better perform. And it does!
First, the 2.4 GHz 12X is much faster
than a PCM system. In the latter, several
68 MODEL AVIATION
Right: Two instruction guides are
included. JR provides a concise, stepby-
step guide for setting up a complex
aerobatic model, a competition
helicopter, and what appears to be an
advanced sailplane.
JR sells several neck-strap adjusters
separately to match the included neck
strap. The adjusters (item SPM6703) keep
the transmitter balanced and level, despite
the short antenna.
Left: Both instructional guides
include detailed instructions,
definitions, and screen shots of most
programming steps.
The 12X is capable of complex programming required for a competition Pattern model
such as the Prestige (R). Hangar 9’s P-47 (L) not only needs aerobatic trim programming,
but also requires 11 channels to eliminate roll coupling, stop adverse yaw, light the glow
plug, and coordinate flaps.
Modulation: 2.4 GHz
Weight: 1.3 ounces (total)
Current drain: 70 mA (including
signal)
Size: 1.48 x 2.1 x .628 inches (main)
Antenna length(s): Approximately
2 inches
Intention: Full range
JR R1221 DSM2 Receiver Specifications
analog-to-digital transformations must
occur, which takes time. The 12X
transmits in digital, eliminating the
translation phases. The time between
stick movement and servo response is
called the “latency period,” and the
12X’s is extremely short (referred to as
“low” for some reason).
Many pilots may think that the
response-speed increase will go
unnoticed. But advanced servos are so
fast (.06-.15 second) that any latency is
noticeable, even when flying a trainer.
Second, the 12X has a resolution of
2048; that’s 2,048 discrete servomovement
positions in the 60° arc of the
servo output arm. This translates into
extreme precision and ultimate aircraft
control.
Most sport 2.4 GHz radios are 1024
systems—half as exact as the 12X. The
high resolution becomes apparent while
flying any sport aerobatic airplane, but
precision machines such as those in
IMAC competition and Pattern and F3C
and 3-D helicopters literally revel in it.
To best utilize the 2048 resolution,
Type: Pro-level computer
Skill level: Advanced pilots
Number of proportional
channels: 12
Safety features: ModelMatch,
Smart Safe for electrics; fail-safe
(two)
Model memory: 50 plus computer
storage
Frequency: 2.4-2.483 GHz
Modulation: Direct spread spectrum
(DSM2/DSM1) plus DuaLink
Channel resolution: 2048
Power supply: 9.6-volt, 2000 mAh
NiMH battery
Current drain: 180 mA DSM2 or
280 mA DSM1
Temperature range: 30° (screen
disappears)
Trim type: Analog, throttle; all
others, digital
Gimbal type: Four ball bearings,
adjustable stick tension
View screen: 4.25 x 1.3 inches,
backlit
Program input: Roller/push button
with switches
Trainer function: Fully
programmable
Number of switches: 18
Number of sliders: One (throttle
trim)
Transmitter battery: 2000 mAh
NiMH
Included: JR R1221 DSM2 receiver,
aluminum transmitter case
Programming features: Aircraft,
helicopter, sailplane
Street price: $1,499
JR 12X General Specifications
03sig3.QXD 1/26/09 12:45 PM Page 68
March 2009 69
Airplane Standard: Servo reverse, travel adjust, exponential, subtrim, throttle hold, throttle curve, servo speed, snap roll,
aileron differential, aileron-to-rudder mix, elevator-to-flap mix, flap-to-elevator mix (flap system), eight programmable mixes
(five curved), flaperon, V-tail and elevon mixing
Airplane Advanced: Servo balance, triple rates (aileron/elevator/rudder), knife-edge mix, five flight modes, twin-engine mix,
control stick as mix switch, pitch curve (adjustable propellers), aileron-to-flap mix, internal model memory backup copy
system, etc. (See text.)
Helicopter Program Features: Six swashplate types (normal, two-servo 180°, three-servo 120°, three-servo 140°, threeservo
90°, four-servo 90°); programmable trainer system (selectable channels for student control); gyro sensor; servo speed;
governor; tail curve; dual pitch; swashplate mix; pitch curve; eight programmable mixes; built-in cyclic-to-throttle mixing for
aileron, elevator, rudder; electronic 3-D cyclic ring to prevent overdriving cyclic servos with combined aileron and elevator
commands; programmable servo speed
Sailplane Program Features: Ability to assign switches for channels and functions, rudder-to-spoiler mix, aileron-torudder
mix, flap rate, brake system, eight program mixes (five curved), trim system adjustment, as many as five fully
programmable flight modes that can be named, tip aileron programming, fully programmable motor function, camber
programming for each flight mode, servo monitor (automatically renames channels according to assignments), warning system
that allows alarms to be custom programmed for various switch and stick positions MA
—Frank Granelli
JR12X Notable Features
you must employ digital servos because
they are more exact than analog servos. All
12 of the channels are 2048 resolution and
are equally fast and proportional.
There is no closer bond between pilot
and model than when using a 2048, lowlatency,
2.4 GHz system such as the 12X.
The pilot’s “feel” is amazing and the
feedback is immediate. Control
improvement is so stunning that most
competition pilots (I am included) must
add several extra exponential points until
they become accustomed to the enhanced
control.
Of particular note is the much faster,
more controllable throttle response. Stall
turns and snap rolls suddenly become
much easier to time correctly.
Third, the 12X is the ultimate in
programming simplicity. As with all JR
systems, there are two programming
stages: System and Function modes. The
former covers all operations that usually
need to be set only once, including
selecting an aircraft, determining its type
(airplane, helicopter, or glider), naming it,
setting the wing type, setting switch
responsibilities, etc.
When System Mode is selected, all the
paradigms appear at once on the screen;
there is no paging and scrolling to find the
right subject. Just roll the button until the
proper function is highlighted and then
press the same rolling button. This not
only saves time, but it also makes
programming so easy that the pilot might
want to experiment.
The same is true for Function Mode;
press the “LIST” button and all the settings
appear on one page. Those are things we
change frequently, such as knife-edge trim
(the 12X has a programming page just for
setting rudder-elevator/aileron mixes for
straight and trimmed knife edges), subtrim,
exponential, aileron-rudder mixing, stepmixing,
regular programmable mixing, and
many more. Just roll, highlight, and push
the button.
As difficult to explain how easy this
transmitter is to program is how true it is.
And on the topic of programming, many
features are unique to the 12X. Following
are several of them.
• The knife-edge trim page mixes rudder to
both aileron and elevator in one mix.
• Dual elevator servos can be mixed from a
single page, including in-flight trim
changes.
• The 12X has a form of servo matching:
the Balance function mixed with the servo
speed adjuster, which matches servo
movement and speed so that multiple
servos moving a single control surface
function identically.
• The Balance function, a curve mix, also
adjusts for separate elevator half
geometries, assuring equal and matching
elevator response.
• The main control sticks can be used as
mixing on/off switches. This is useful for
smoke-system setups and more.
• The 12X has five curve mixes and five
Flight Modes—not just three of each.
Why do you need five Flight Modes?
you might ask. Aren’t the three available
in most near-high-end radio systems
enough? Yes, sometimes, but more may be
required in competition.
My Prestige, a competition Pattern
model, flies well in calm air using a threeblade
propeller but uses a two-blade in
heavy crosswind competition. As the
three-blade produces extra torque, it
requires a certain amount of elevator trim
and either proverse or adverse aileron
input for straight knife-edge flight and
vertical climbs. The two-blade propeller
requires a different trim setting for these
maneuvers—without aileron mixing.
Flight Modes are really different
program settings for the same airplane.
Simply flipping the switch puts a model in
the trim setting that is best suited to
changing flight or equipment conditions.
FM-1 is for the three-blade and FM-2 is
for windy weather with a two-blade
propeller.
The Prestige requires more elevator
input for inverted snap rolls than it can use
to fly Pattern. For that maneuver, I
normally use the Snap Roll button.
Since it is best to snap away from the
flightline, two more Flight Modes,
programmed with opposite outside snaproll
directions, are needed to suit either left
or right Pattern entries with the selected
propeller. That is four Flight Modes total.
A sport or IMAC competition airplane
may need FM-1 for normal flying, FM-2
for 3-D work, and FM-3 for Freestyle
control settings. Scale airplanes can use
one Flight Mode for normal flying, another
trimmed and set for the slow pass with
everything hanging out, and a third, even a
fourth, when imitating full-scale flight
(e.g., lower max power settings and slightly
reflexed ailerons to keep that Jenny from
climbing and turning like it’s an F-22).
Flipping a switch can convert your
airplane into five different models. If your
current transmitter has Flight Modes and
you don’t use them, you are missing a
great deal of what the system has to offer.
If you still don’t use them after reading
this, shame on me for not convincing you
to give them a try. The 12X’s Flight Mode
system is almost the most versatile and
easy to program I have flown.
The 12X is imperfect in just one respect; it
03sig3.QXD 1/26/09 12:48 PM Page 69
is available only without the usual throttlestick
indentations (“throttle clicks”).
According to JR, that was a request from its
helicopter and Scale Aerobatics team pilots.
I can’t argue with the company’s
champion fliers, but us lesser pilots could
use some throttle detents to help keep
power levels constant during rudderintensive
slow and point rolls. Fortunately
for us “normal” humans, JR will install
throttle detents free for any pilot who wants
them. That is the only 12X “feature” I
found to be difficult.
However, the 12X has so many good
features that it is senseless to worry about
throttle-stick detents. There are so many
features that it is impossible to list them all,
but I do have some favorites.
All trim screens have a throttle and/or
servo “hold” setting that makes safe
throttle-based trim changes possible while
the power system is operating. This is
especially useful when making those two
dozen landings while trying to trim knife
edges or vertical climbs.
The knife-edge mix (rudder-toelevator/
aileron mix) can be switched by the
throttle stick so that the trim settings
operate during flight but are inhibited
during stall turns and landings. The typical
down-elevator required for knife edge can
ruin a stall turn’s pitch and cause trim
problems during landing. The 12X
eliminates this problem. All the mixes can
be switched by the transmitter-stick
position, making for a seemingly infinite
variety of mix-to-mix settings.
The amount of aileron differential
needed for axial roll performance varies
with throttle settings and airspeed. The 12X
will use the throttle-stick position to alter
the programmed aileron differential rate so
that it is more pronounced at low throttle
settings as adverse yaw effects increase
with decreasing airspeed.
The twin-engine setting ensures that
both power plants operate at the same rpm
throughout the throttle range. The normal
twin yaw effects disappear, and only one
mix setting is required instead of multiple
mixing.
The customary throttle trim lever can
control either both engines simultaneously
or each engine can have independent trim
levers. This is useful for practicing singleengine
flying.
The 12X has two trim settings. The
normal one functions like almost all trim
levers do; it moves the center point and the
endpoint. The amount of movement can be
adjusted from four points per beep, coarse
trim, down to one point per beep for extrafine
trim adjustments.
Although the second LST (Limited
Standard Trim) function is also adjustable,
the trim button controls only the center
point. This prevents overdriving and
damaging servos at the endpoints. The
digital trim settings can apply to one Flight
Mode or can be made common to all Flight
Modes.
When used as a “master” in a buddy-box
system, the student can be assigned one or
more control functions, which the instructor
determines. The student can start with
aileron and elevator control only and then
move up to throttle and/or rudder as skills
improve.
The Dual Channel function allows all
control surfaces to be powered by separate
servos while remaining responsive to the
single digital trim buttons. This is a great
feature when using independent elevator
halves or ailerons.
The 12X has digital button trims on the
flight control surfaces but a trim lever on
the throttle. This eliminates the need for a
separate engine kill switch and allows the
pilot to determine and set the engine idle
rpm by feel during flight.
Two switchable aileron differential
settings are available per the Flight Mode.
The elevator-to-flap mix allows for
reflexing the ailerons for 3-D maneuvers
such as the Harrier and the Wall.
The flap-to-elevator system not only
compensates for pitch changes that flap
deployment causes, but the compensation
can be timed in 0.1-second intervals so that
both surfaces move at the same speed,
maintaining perfect trim during flap
deployment or retraction. The Auto Land
feature does this automatically.
The 12X has a mix monitor that displays
all programmed mixes, dual channels,
selected switches, and control surfaces so
that the pilot can determine the aircraft’s
setup with one glance. This radio system
includes software and connection hardware
so that it can copy programs to and from
another 12X or your computer.
The included JR R1221 receiver is
actually four receivers. The main unit has
three satellite receivers that mount remotely
9, 12, and 24 inches from the main receiver
to ensure the strongest possible reception in
all flight attitudes. The R1221 has full 2048
resolution plus dual flight-battery inputs for
greater safety.
This report has probably missed a dozen
important 12X capabilities. The system
arrives with the usual detailed instruction
book, but it also has an Applications and
Programming Guide. This step-by-step
manual goes through, in detail, the setup
and programming of a complex Giant Scale
IMAC airplane, a competition helicopter,
and a complex sailplane.
The sailplane guide covers such details
as Cruise Mode, camber adjustments,
airborne braking systems, launch and
landing modes, and much more that Soaring
pilots will love. The helicopter guide
includes setting up swashplate mixing,
cyclic mixes, throttle and pitch curves,
throttle holds, and other important trimming
operations. Jet pilots will love the extra
flight modes and the “stick as switch”
options.
Advanced radio studies traditionally end
with the phrase “this radio can grow with
the pilot.” The JR 12X leads the pilot to
that growth. MA
Frank Granelli
[email protected]
Sources:
Horizon Hobby Distributors
(800) 338-4639
www.jrradios.com
Other Printed Reviews:
Model Airplane News: November 2008