INSTRUCTION AND 

PROGRAMMING MANUAL

X9303 2.4

9-CHANNEL COMPUTER RADIO 

SYSTEM WITH SPEKTRUM 2.4GHz DSM 

TECHNOLOGY 
Table of Contents

G-2

Section 1: Using the Manual .........................................................................................................G-9

Features......................................................................................................................................................... G-9

Specifications................................................................................................................................................ G-9

Section 2: Transmitter and Receiver Specifications.................................................................G-9

JR X9303 Transmitter..................................................................................................................................... G-9

JR R921 Receiver ..........................................................................................................................................G-10

Features.......................................................................................................................................................G-10

Specifications..............................................................................................................................................G-10

Section 3: Component Specifications.......................................................................................G-11

Servo Specifications......................................................................................................................................G-11

Charger Specifications.................................................................................................................G-11

Airborne Battery Pack.................................................................................................................G-11

Airborne Battery Pack Specifications...................................................................................................G-11

Battery Charging...........................................................................................................................G-12

Transmitter/Receiver....................................................................................................................................G-12

JR Transmitter Charging...........................................................................................................................G-12

Using the Included Charger....................................................................................................................G-12

X9303 2.4 Transmitter Features (Mode 2 Airplane Shown)...............................................G-13

X9303 2.4 Transmitter Features (Rear)...................................................................................G-14

Battery Cover............................................................................................................................................G-14

X9303 2.4 Transmitter Features (Internal).............................................................................G-15

Control Stick Tension Adjustment.............................................................................................................G-15

Back of Transmitter (Mode 2)................................................................................................................G-15

Advanced Digital Trims................................................................................................................................G-16

Control Stick Length....................................................................................................................................G-16

Neckstrap Attachment.................................................................................................................................G-16

Installing the Receiver..................................................................................................................................G-17

Installing the JR R921 ...............................................................................................................................G-17

Model Match ..................................................................................................................................G-18

Other Important Installation Tips.........................................................................................................G-18

Binding .............................................................................................................................................G-19

How To Bind...................................................................................................................................................G-19

Fail-Safe Functions.........................................................................................................................................G-20

SmartSafe ........................................................................................................................................................G-20

Receiver Power Only...............................................................................................................................G-20

After Connection......................................................................................................................................G-20

Preset Fail-Safe...............................................................................................................................................G-20

Receiver Power Only...............................................................................................................................G-20

After Connection......................................................................................................................................G-20

Programming SmartSafe ..............................................................................................................................G-20

(All Spektrum Aircraft Receivers).........................................................................................................G-20

Programming Preset Fail-Safe.....................................................................................................................G-21

(JR R921 and Spektrum AR 9000 Receivers Only) ...........................................................................G-21
Table of Contents

G-3

Standard Range Testing ................................................................................................................G-21

Range Testing the X9303 2.4..................................................................................................................G-21

Advanced Range Testing Using a Flight Log............................................................................G-22

Advanced Range Testing the X9303 2.4...............................................................................................G-22

Flight Log—Optional for JR R921 Receiver...........................................................................G-23

Using the Flight Log..................................................................................................................................G-23

Receiver Power System Requirements....................................................................................G-24

Recommended Power System Guidelines...............................................................................................G-24

Flash Memory ................................................................................................................................G-25

Battery Alarm and Display..........................................................................................................G-25

Tip on Using 2.4GHz Systems...................................................................................................G-25

AIRPLANE – ACRO MODE.........................................................................................................A-1

Flight Modes..................................................................................................................................................A-1

ACRO PROGRAMMING - PLEASE READ ...........................................................................................A-1

ACRO - GETTING STARTED – SYSTEM MENU BASICS................................................................A-1

ACCESS THE SYSTEM MENU......................................................................................................................A-2

SELECT A MODEL MEMORY.......................................................................................................................A-2

RESET THE MODEL........................................................................................................................................A-3

TO ACTIVATE THE ACRO MODE..............................................................................................................A-4

ENTER A NAME FOR THE MODEL...........................................................................................................A-4

ACRO - SYSTEM MENU - ADVANCED FUNCTIONS........................................................A-5

FLIGHT MODES ..............................................................................................................................................A-6

To Activate Flight Modes................................................................................................................................A-7

TRIM:COM (Flight Modes)............................................................................................................................A-8

D/R:SW (Flight Modes) ..................................................................................................................................A-8

SWITCH ASSIGNMENTS..............................................................................................................................A-9

FLAP TRIM ON/OFF.......................................................................................................................................A-9

ACTIVATE/INHIBIT SWITCHES............................................................................................................... A-10

WING TYPE...................................................................................................................................................A-11

WING Parameter – (Wing Type).............................................................................................................. A-12

V-tail (Wing Type)..........................................................................................................................................A-14

Dual Channels (Wing Type)........................................................................................................................ A-14

Twin E. (Wing Type)......................................................................................................................................A-16

TRIM STEP......................................................................................................................................................A-18

ACRO – FUNCTION LIST.................................................................................................................... A-19

REV.SW – SERVO REVERSING ................................................................................................................ A-19

SUB TRIM........................................................................................................................................................A-20

TRVL ADJ. – TRAVEL ADJUST................................................................................................................... A-21

D/R & EXP – DUAL RATE AND EXPONENTIAL ............................................................................... A-22

THRO CURV – THROTTLE CURVE........................................................................................................ A-23

FLAP SYS. – FLAP SYSTEM......................................................................................................................... A-25

AUTO LAND (Flap System)....................................................................................................................... A-26

ELEV – ELEVATOR COMPENSATION (Flap System).......................................................................... A-27
Table of Contents

G-4

FLAP – (Flap System) ...................................................................................................................................A-28

FM0-FM2 (Flap System)............................................................................................................................... A-29

Delay (Flap System)......................................................................................................................................A-30

ELEFLP M – ELEVATOR-TO-FLAP MIXING...................................................................................... A-31

AILRUD M – AILERON-TO-RUDDER MIXING ............................................................................. A-32

AIL DIFF. – AILERON DIFFERENTIAL..................................................................................................... A-33

SRV. SPEED – SERVO SPEED...................................................................................................................... A-35

SNAP ROLL.................................................................................................................................................... A-36

GYRO SYS. – GYRO SYSTEM.................................................................................................................... A-37

GYRO CONNECTIONS (Gyro System)................................................................................................ A-37

FIXED GYRO GAIN (Gyro System)........................................................................................................ A-38

STICK OVERRIDE GYRO GAIN (Gyro System).................................................................................. A-39

PROG MIX – PROGRAMMABLE MIXERS ............................................................................................. A-40

STANDARD PROGRAMMABLE MIXER – Example: DOWN ELEVATOR AT IDLE..................... A-41

MULTI-POINT MIXER – Example: ELIMINATE PITCH-COUPLING............................................... A-43

TRAINER – TRAINER SYSTEM................................................................................................................. A-45

XP9303 USED AS MASTER (INSTRUCTOR) – (Trainer System)..................................................... A-45

X9303 2.4 USED AS SLAVE (STUDENT) – (Trainer System)............................................................ A-46

TIMER – TIMER SYSTEM............................................................................................................................. A-47

MONITOR...................................................................................................................................................... A-48

UTILITY FUNCTIONS................................................................................................................................A-49

COPY – COPY THE CURRENTLY SELECTED MODEL TO ANOTHER MODEL MEMORY... A-49

TRANSFER – TRANSFER THE MODEL TO ANOTHER TRANSMITTER OR TO DataSafe....... A-51

RECEIVE A MODEL INTO THE X9303 2.4 – (Transfer function)..................................................... A-51

RECEIVE A MODEL INTO THE X9303 2.4 – (Transfer function)..................................................... A-52

SUB TRIM USAGE AND MECHANICAL ADVANTAGE..................................................................... A-53

SUB TRIM....................................................................................................................................................A-53

MECHANICAL ADVANTAGE............................................................................................................... A-53

DUAL RATES AND EXPONENTIAL CURVES ..................................................................................... A-54

Setup Sheet (Aircraft)..................................................................................................................................A-55

X9303 2.4 Helicopter – Heli Mode ...........................................................................................H-1

INTRODUCTION...................................................................................................................................... H-1

Heli PROGRAMMING - PLEASE READ.................................................................................................... H-1

HELI - GETTING STARTED – SYSTEM MENU BASICS....................................................................... H-1

ACCESS THE SYSTEM MENU..................................................................................................................... H-2

Model SEL- Model Selection......................................................................................................................... H-2

Copy – Copying the Currently Selected Model to Another Model Memory................................... H-3

Data Reset – RESET THE MODEL ............................................................................................................. H-5

Type Select – TO ACTIVATE THE HELI MODE....................................................................................... H-6

MDL Name-ENTER A NAME FOR THE MODEL................................................................................... H-6

TRANSFER – TRANSFER THE MODEL TO ANOTHER TRANSMITTER OR TO DATASAFE .... H-7

TRANSFER A MODEL FROM THE X9303 2.4 – (Transfer function) – To Send.............................. H-7

TRANSFER A MODEL TO THE X9303 2.4 – (Transfer function) – To Receive............................... H-8

TRIM STEP........................................................................................................................................................ H-9
Table of Contents

G-5

HELI - SYSTEM MENU - ADVANCED FUNCTIONS..........................................................................H-10

ADDITIONAL FLIGHT MODES 3 and 4 ...............................................................................................H-10

RUD TRIM: COM – (Flight Mode Trim Options)...................................................................................H-11

SWITCH ASSIGNMENTS...........................................................................................................................H-11

ACTIVATE/DEACTIVATE SWITCHES.....................................................................................................H-12

GOVERNOR PROGRAM ACTIVATION................................................................................................H-12

SWASH TYP-SWASHPLATE TYPE............................................................................................................H-13

Accessing the Swashplate Type Function.................................................................................................H-13

FUNCTION MODE.....................................................................................................................H-14

HELI – FUNCTION LIST............................................................................................................................H-14

D/R & EXP – DUAL RATE AND EXPONENTIAL ...............................................................................H-14

Auto Dual Rate..............................................................................................................................................H-15

REV.SW - SERVO REVERSING .................................................................................................................H-15

Sub Trim...........................................................................................................................................................H-16

TRVL ADJ. – TRAVEL ADJUST...................................................................................................................H-17

Swash Mix- CCPM SWASHPLATE Mixing .............................................................................................H-18

Variations of CCPM Mixing ....................................................................................................................H-18

CCPM Servo Connection/Channel Numbers....................................................................................H-18

Accessing the Swashplate Mixing Function.........................................................................................H-19

CCPM Exponential (EXP)...........................................................................................................................H-19

THRO HOLD- THROTTLE HOLD..........................................................................................................H-20

Accessing the Throttle Hold Function .................................................................................................H-20

Stick Auto/Auto Cut Setting.......................................................................................................................H-21

Hold Delay......................................................................................................................................................H-21

THRO CURV – THROTTLE CURVES......................................................................................................H-22

Accessing the Throttle Curve Function...............................................................................................H-23

Throttle Trim Lever Function.....................................................................................................................H-24

Hovering Throttle Lever..............................................................................................................................H-24

Throttle Curve Exponential .......................................................................................................................H-24

Accessing the Throttle Curve Exponential Function........................................................................H-24

PIT. CURV/PITCH CURVES Function.......................................................................................................H-25

Accessing the Pitch Curve Function.....................................................................................................H-25

Hovering Pitch Lever....................................................................................................................................H-26

Example of Throttle Curve and Pitch Curve Settings......................................................................H-26

Accessing the Revolution Mixing Function .........................................................................................H-27

Setting up Revolution Mixing..................................................................................................................H-27

REVO.MIX/Revo Mix Function: Non Heading Lock Gyros Only.......................................................H-27

GYRO SENS/Gyro Gain Function.............................................................................................................H-28

Accessing the Gyro Gain Function .......................................................................................................H-28

Gyro Remote Gain Connections: JR G500T, JR770 and Others...................................................H-29

Remote Gain Gyros.....................................................................................................................................H-29

Mixing – Cyclic-to-Throttle Mixing...........................................................................................................H-29

Rudder-to-Throttle Mixing .........................................................................................................................H-30

Accessing the Cyclic-to-Throttle Function.........................................................................................H-31
Table of Contents

G-6

Aileron-to-Throttle and Elevator-to-Throttle Mixing...........................................................................H-31

Setting the Desired Flight Modes for Cyclic-to-Throttle Mixing...................................................H-31

GOVERNOR- GOVERNOR FUNCTION .............................................................................................H-32

Accessing the Governor Function ........................................................................................................H-32

PROG MIX 1-6 – PROGRAMMABLE MIXES 1 through 6..................................................................H-33

Swashplate Timing Mixes Example: Elevator-to-Aileron (Corrects Vertical Tracking)....................H-35

Swashplate Timing: Aileron-to-Elevator (Corrects Rolling Maneuvers)............................................H-37

STANDARD PROGRAMMABLE MIXES – Example: Right Aileron with Positive Pitch............H-39

MULTI-POINT MIXES – Example: FMOD to Gear Mixing (Retract and other Functions).........H-41

Trainer – Programmable Trainer System..................................................................................................H-44

X9303 2.4 USED AS MASTER (INSTRUCTOR) – (Trainer System)............................................H-44

X9303 2.4 USED AS SLAVE (STUDENT) – (Trainer System)........................................................H-45

Timer – Timer System .................................................................................................................................H-46

MONITOR- SERVO MONITOR ...............................................................................................................H-47

Setup Sheet (Helicopter).............................................................................................................................H-48

Sailplane – GLID Mode...................................................................................................................S-1

SYSTEM MODE GLID FEATURES ...........................................................................................................S-1

FUNCTION MODE GLID FEATURES ...................................................................................................S-1

System Mode......................................................................................................................................................S-2

System Mode......................................................................................................................................................S-2

To enter System Mode:................................................................................................................................S-2

Model Select.......................................................................................................................................................S-3

Copy – Copying the Currently Selected Model to Another Model Memory.....................................S-4

Model Name ......................................................................................................................................................S-6

Type Select..........................................................................................................................................................S-6

Model Reset.......................................................................................................................................................S-7

TRANSFER – Transfer the Model to Another Transmitter or to DataSafe .........................................S-8

TRANSFER a model from the X9303 2.4 – (Transfer function)............................................................S-8

TRANSFER a model to the X9303 2.4 – (Transfer function).................................................................S-9

Trim Step.......................................................................................................................................................... S-10

Device Select................................................................................................................................................... S-11

Flight Modes................................................................................................................................................ S-11

Activating and Assigning Flight Modes....................................................................................................... S-12

Motor Function .............................................................................................................................................. S-13

Flap and AUX Functions............................................................................................................................... S-14

Activating / Inhibiting Channels.............................................................................................................. S-14

Wing Type ........................................................................................................................................................ S-15

Function Mode ........................................................................................................................................... S-16

D/R & EXP – DUAL RATE AND EXPONENTIAL ................................................................................ S-18

REV.SW – SERVO REVERSING ................................................................................................................. S-19

SUB TRIM......................................................................................................................................................... S-20

TRVL. ADJ - TRAVEL ADJUST..................................................................................................................... S-21

Elevator-to-Flap Mix ...................................................................................................................................... S-21

Aileron-to-Flap Mix ....................................................................................................................................... S-22

Differential....................................................................................................................................................... S-22
Table of Contents

G-7

Camber Adjust................................................................................................................................................ S-23

Camber Mix .................................................................................................................................................... S-24

Aileron-to-Rudder Mix................................................................................................................................. S-25

Butterfly Mix (Landing Flaps)....................................................................................................................... S-26

Flap Rate........................................................................................................................................................... S-27

Motor Hold ..................................................................................................................................................... S-27

Programmable Curve Mix 1 (Programmed for Spoiler-to-Elevator Mix).......................................... S-28

PROG MIX - PROGRAMMABLE MIXERS............................................................................................... S-29

MULTI-POINT PROGRAMMABLE MIXER ............................................................................................. S-33

Trainer – Programmable Trainer System................................................................................................... S-36

X9303 2.4 USED AS MASTER (INSTRUCTOR) – (Trainer System)............................................. S-36

X9303 2.4 USED AS SLAVE (STUDENT) – (Trainer System)......................................................... S-37

Timer................................................................................................................................................................ S-37

Monitor............................................................................................................................................................ S-38

Programming a 6-Channel Sailplane by Engineering Manager John Adams......................S-39

Channel Assignment.................................................................................................................................. S-41

Step #1 Servo Assignment .......................................................................................................................... S-41

Step #2- System Mode.................................................................................................................................. S-42

Step #3 Selecting a Model Memory........................................................................................................... S-42

Step #4 Selecting Model Type...................................................................................................................... S-43

Step #5 Naming a Model.............................................................................................................................. S-43

Step #6 Turning Off the Spoiler Stick Trim............................................................................................... S-44

Step #7 Establishing Flight Modes.............................................................................................................. S-44

Step #8 Wing and Tail Type Select.............................................................................................................. S-45

Step #9 Entering FUNC.LIST...................................................................................................................... S-45

Step #10 Servo Reversing............................................................................................................................ S-46

Step #11 Sub Trim.......................................................................................................................................... S-47

Step #12 Travel Adjust................................................................................................................................... S-48

Step #13 Butterfly (Landing Flaps)............................................................................................................. S-48

Setting-up Flight Modes............................................................................................................................ S-49

Launch Mode Setup................................................................................................................................... S-49

Step #14 Spoiler to Elevator Curve Mix (Programmable Mix 1) ....................................................... S-49

Step #15 Launch Pre-sets ............................................................................................................................ S-50

Step #16 Dual Rate and Exponential......................................................................................................... S-51

Step #17 Elevator-to-Flap Mix .................................................................................................................... S-51

Step #18 Aileron-to-Flap.............................................................................................................................. S-52

Step #19 Aileron Differential....................................................................................................................... S-52

Flaperon Mix ............................................................................................................................................... S-53

Step #20 Flap Rate, Camber Mix and Camber Adjust........................................................................... S-53

Step #21 Flap Rate, Camber Mix and Camber Adjust (continued).................................................... S-54

Flaperon Mix ............................................................................................................................................... S-54

Flaperon Mix Delay.................................................................................................................................... S-54

Setting up Cruise Mode............................................................................................................................ S-55

Step #22- Aileron-to-Rudder Mix ............................................................................................................. S-55

Step #23 Cruise Pre-sets............................................................................................................................. S-56
G-8

Step #24 Dual Rate and Exponential......................................................................................................... S-56

Step #25 Elevator-to-Flap Mix .................................................................................................................... S-57

Step #26 Aileron-to-Flap.............................................................................................................................. S-58

Step #27 Aileron Differential....................................................................................................................... S-58

Flap Rate ...................................................................................................................................................... S-59

Flaperon Mix ............................................................................................................................................... S-59

Step #28 Flap Rate, Camber Mix and Camber Adjust........................................................................... S-59

Step #29 Flap Rate, Camber Mix and Camber Adjust (continued).................................................... S-60

Flaperon Mix Delay.................................................................................................................................... S-60

Setting Up Land Mode .............................................................................................................................. S-61

Step #30 Aileron-to-Rudder Mix .............................................................................................................. S-61

Step #31 Land Pre-sets................................................................................................................................. S-62

Step #32 Dual Rate and Exponential......................................................................................................... S-63

Step #33 Elevator-to-Flap Mix .................................................................................................................... S-64

Step #34 Aileron-to-Flap.............................................................................................................................. S-64

Step #35 Aileron Differential....................................................................................................................... S-64

Flaperon Mix ............................................................................................................................................... S-65

Flaperon Mix ............................................................................................................................................... S-65

Step #36 Flap Rate, Camber Mix and Camber Adjust........................................................................... S-65

Step #37 Flap Rate, Camber Mix and Camber Adjust (continued).................................................... S-66

Step #38 Aileron-to-Rudder Mix .............................................................................................................. S-66

Flaperon Mix Delay.................................................................................................................................... S-66

Setup Sheet (Sailplane).................................................................................................................................. S-67

Servo Precautions..........................................................................................................................................W-1

General notes.................................................................................................................................................W-1

Federal Aviation Administration..................................................................................................................W-2

1. Purpose ....................................................................................................................................................W-2

2. Background..............................................................................................................................................W-2

3. Operating Standards.............................................................................................................................W-2

Warning........................................................................................................................................................W-3

Warranty Period ........................................................................................................................................W-3

Limited Warranty .......................................................................................................................................W-3

Damage Limits............................................................................................................................................W-3

Safety Precautions......................................................................................................................................W-3

Questions, Assistance, and Repairs........................................................................................................W-3

Warranty and Service Information ............................................................................................................W-3

Warranty and Service Information ............................................................................................................W-4

Inspection or Repairs................................................................................................................................W-4

Warranty Inspection and Repairs...........................................................................................................W-4

Non-Warranty Repairs.............................................................................................................................W-4

Safety, Precautions, and Warnings...........................................................................................................W-4

Instructions for Disposal of WEEE by Users in the European Union............................................W-5

FCC Information........................................................................................................................................W-5
JR X9303 Transmitter

Section 2: Transmitter and Receiver Specifications

Section 1: Using the Manual

G-9

JR’s X9303 2.4 offers airplane, helicopter and sailplane 

pilots sophisticated programming that JR’s 9303 is 

famous for with the added benefits of fully integrated 

Spektrum 2.4GHz DSM® radio link technology. DSM 

(Digital Spektrum Modulation) technology offers a far 

superior RF link than narrow band 72MHz FM and PCM 

systems, providing a higher level of confidence and 

safety. Now with even the most sophisticated models 

up to 9 channels, you’ll no longer have to wait for an 

open frequency, worry about someone unintentionally 

powering up on the same frequency, or have to plan a 

frequency-based flight matrix for competition. And for 

response-critical aircraft like 3D helicopters and airplanes, 

latency (the time it takes for a stick input to translate to a 

servo output) is significantly reduced providing a more 

responsive precise connection to your model.

Features

• Fully integrated 2.4GHz Spektrum RF link 

• Sophisticated three-model-type programming: Airplane, Helicopter, Sailplane

• Patented DuaLinkTM Technology

• ModelMatchTM

• ServoSyncTM

• Rolling Selector input

• Digital 3+1 trims

• 30-model memory

Specifications

• Model number—Airplane/Sailplane (JRP2910), Helicopter (JRP2920)

• Number of channels—9

• Modulation type—Direct Sequence Spread Spectrum DSM2/ DSM1 protocol

• Band—2.400 to 2.483GHz

• Spectral capacity—40 simultaneous systems

• Transmitter Current—180mA/DSM2 280mA/ DSM1

• Resolution—2048 w/R921 receiver

In the front of this manual you will find common 

transmitter features and specifications plus information 

on the included components and accessories. Guidelines 

for receiver and servo installation are also included. In 

each section of this manual (Air, Heli and Sailplane) are 

instructions for adjusting model-specific programming 

and functions. An explanation of the purpose of each 

programming function is provided, followed by an 

illustration of its corresponding LCD display and 

instructions on how to access and adjust the function.

A blank data sheet has been included at the end of 

each section, as well as on the JR web site. Once all 

data has been input for a particular model, it is highly 

recommended that you record these values and settings 

on a copy of the data sheet, so in the rare event of a loss 

of memory, these settings are available. 

Note: The manual for the X9303 2.4 manual is posted 

online at www.horizonhobby.com in the support section or 

it can be ordered from your local hobby dealer or directly 

from Horizon Hobby.
JR R921 Receiver

G-10

The R921 receiver combines two internal with one or 

two (optional) remote receivers, offering superior path 

diversity. The radio system simultaneously transmits 

on two frequencies, creating up to four RF paths on two 

different 2.4GHz channels. This multi path redundancy, 

plus the fact that each of the up to 4 receivers are located 

in different locations throughout the aircraft exposes each 

to a different RF environment creating a superior RF 

link in all conditions. The JR R921 allows the use 

of an optional Flight Log Data Recorder (SPM5940) to 

be used. The flight log plugs into the data port and 

provides quality of RF link data of the previous flight 

allowing the confirmation of the operational performance 

of the systems.

Features

• 9 channels 

• 2 internal receivers

• 1 or 2 (optional) remote receiver(s)

• Patented multi-link technology 

• Two types of fail-safe—SmartSafe and Preprogrammed fail-safe

• Flight Log compatible

Specifications

• Number of Channels—9 

• Modulation—DSM2 

• Band—2.400 to 2.4835GHz 

• Dimensions (WxLxH)—.35”x2.06”x0.55”

• Weight—Main 15g/.6oz Remote 3g/.2 oz each

• Current—70mA

• Voltage range—3.5 to 9.6V

Note: The X9303 2.4 is compatible with all current Spektrum DSM aircraft receivers including:

AR6000 6-channel parkflyer receiver 

AR6100 6-channel 3.5-gram parkflyer receiver

AR6200 6-channel full-range receiver

AR7000 7-channel full-range receiver

AR9000 9-channel full-range receiver

Important: When using the X9303 2.4 with parkflyer receivers (the AR6000 and AR6100), it’s imperative that these 

receivers only be flown in parkflyer-type aircraft (small electric airplanes or mini and micro helicopters). Flying 

receivers designed for parkflyers in larger aircraft could cause loss of control. 
Servo Specifications

Section 3: Component Specifications

Charger Specifications

G-11

Type DS821

Torque 72 oz/in

Speed .19

Weight 1.5 oz

Size (in) (L x W x H) .74x1.50x1.47

Ball Bearing Yes

Motor 3-pole Ferrite

Model Number AD35M05

Input Voltage AC 120V, 60Hz

Output Current 11.6V Tx/110mAh, 5.8V Rx/110mAh

Charging Time 15 hours

Airborne Battery Pack

Airborne Battery Pack Specifications

Model Number B1100

Voltage 4.8V

Size (in) (L x W x H) 2.24 x 0.63 x 1.70

Weight (oz) 4.9
Transmitter/Receiver

Battery Charging

G-12

Note: It is imperative that you fully charge both the 

transmitter and the receiver battery packs prior to 

each flying session and that you check the condition 

of the receiver battery between each flight using 

a reliable battery tester with a built-in load. The 

included wall charger slow charges at a 110mA rate. 

In order to fully charge the included batteries, it’s 

necessary to leave the charger and batteries hooked 

up to the included wall charger for 15 hours.

An optional fast charger can be used to charge both the 

transmitter and receiver batteries, however, it’s imperative 

that the batteries are properly charged and the charge 

condition be checked prior to flight. False peaking is a 

common occurrence with many fast chargers (batteries 

giving an indication the battery is fully charged when 

in fact the battery is only partially charged). False 

peaking can lead to disastrous results and it is the 

pilot’s responsibility to verify the charge condition of the 

batteries before every flight. (Also see Receiver Power 

Requirements page G-24)

JR Transmitter Charging

The center pin on all JR® and SpektrumTM transmitters is 

negative. Therefore, the center pin on all JR chargers is 

negative, not positive. This is different from many other 

manufacturers’ chargers and radio systems. Beware of 

improper connections based on “color-coded” wire leads, 

as they may not apply in this instance. You must make 

sure that the center pin of your JR transmitter is always 

connected to the negative pole for correct polarity.

Note: When using a fast charger to charge the 

transmitter battery do not exceed 1.5 amps (or 

1500mAh) charge rate or damage to the transmitter 

or battery damage can occur.

Using the Included Charger

The pilot lamps should always be on during the charging 

operation. If not, check to make sure that both the 

transmitter and receiver are switched off.

Do not use the charger for equipment other than JR. The 

charging plug polarity may not be the same. Equipment 

damage can result.

Do not use other manufacturers’ after-market accessories 

that plug into the transmitter’s charging jack if you are 

unsure of the polarity compatibility with your radio. Seek 

expert advice to avoid possible damage.

During the charging operation, the charger’s temperature 

is slightly elevated.

CENTER 

PIN IS 

NEGATIVE

OUTSIDE IS POSITIVE

CHARGER PIGTAIL FOR RECEIVER

CHARGER PIGTAIL FOR TRANSMITTER

BLACK TO POSITIVE

RED TO NEGATIVE

RIGHT SIDE OF TRANSMITTER

RED–POSITIVE / BROWN–NEGATIVE / ORANGE–SIGNAL
X9303 2.4 Transmitter Features (Mode 2 Airplane Shown)

G-13

Trainer Button

Gear Switch

Flap Switch

Elevator 

Dual Rate

Flap Trim

Lever

AUX4/

Rudder Dual 

Aux Trim Rate

Aileron 

Dual Rate

AUX2

Mix Switch

Lever

Elevator/

Aileron Stick

Throttle/

Rudder Stick

Rudder Trim

Throttle Trim

List Button

Enter Button

Clear Button

Power Switch

Aileron Trim

Elevator Trim

Rolling Selector

LCD Display
X9303 2.4 Transmitter Features (Rear)

G-14

Model No. X9303

FCC ID: BRWDAMTX10

IC: 6157 A-BRWDAMT

HORIZON HOBBY, INC. MADE IN JAPAN

Battery Cover

CAUTION: THE BATTERY CONNECTION IS KEYED SO THAT IT CAN ONLY 

BE PLUGGED IN ONE DIRECTION. DO NOT FORCE.
X9303 2.4 Transmitter Features (Internal)

Control Stick Tension Adjustment

G-15

Remove the six transmitter screws from the back cover as 

shown on page G-14. Remove the transmitter back, being 

careful not to cause damage to any components.

Adjust each gimbal tension screw for desired tension 

(counter-clockwise to loosen stick tension; clockwise to 

tighten stick tension). When adjusting the throttle ratchet 

tension, make sure that the adjusting screw does not 

touch the PC board after adjustment is complete.

Back of Transmitter (Mode 2)

THROTTLE TENSION SCREW

RUDDER TENSION SCREW

ELEVATOR TENSION SCREW

AILERON TENSION SCREW
Control Stick Length

Neckstrap Attachment

G-16

Advanced Digital Trims

The X9303 2.4 features Advanced digital trims. On the 

Normal display screen, if a trim lever is moved, the screen 

will automatically change to display the graphic position 

for the trim being adjusted. The X9303 2.4’s Aileron, 

Elevator, and Rudder trim levers feature an audible center 

trim beep. This is helpful in determining the trim levers’ 

center position during flight. In addition, the frequency of 

each trim step changes from full right/up to full left/down, 

allowing the pilot to be aware of the general trim position 

audibly without looking at the transmitter.

By using the Trim Step Function located in the System 

Mode, the amount of travel per each trim step can be 

adjusted as needed to match your specific application.

Please note that when the X9303 2.4 transmitter is turned 

off, the trim values are stored in memory and are recalled 

when the system is turned back on.

Use a 2mm Allen wrench to unlock the setscrew to adjust 

the stick length. Turn the wrench counterclockwise to 

loosen the screw. Then, turn the stick clockwise to shorten 

or counterclockwise to lengthen the overall stick length. 

After the control stick length has been adjusted to suit your 

flying style, tighten the 2mm setscrew. If you desire longer 

sticks, JR® offers a stick (JRPA047) that is approximately 

one inch longer than standard, and has various length 

anodized aluminum stick ends available (JRPA040-

JRPA045). These stick ends are crafted from bar stock 

aluminum, and are available at your local JR dealer.

An eyelet is provided on the face of the X9303 2.4 transmitter 

that allows you to connect a Neck Strap (JRPA023). 

LOOSEN

TIGHTEN

SETSCREW
Installing the Receiver

G-17

Installing the JR R921

The JR R921 incorporates dual internal receivers, and one 

or two remote receivers offering the security of up to four 

simultaneous RF links for the ultimate in multi-path RF 

security. Two internal receivers are located on the main 

PC board, while a third remote receiver must be plugged 

into one of the antenna ports in order for the system to 

operate. Optionally, a second remote receiver can be 

plugged into the remaining remote antenna port giving 

a total of four operational receivers. By locating these 

receivers in different locations throughout the aircraft, 

each receiver is exposed to its own RF environment, 

greatly improving path diversity (the ability of the receiver 

to see the signal in all conditions).

Note: The JR R921 requires that at least one remote 

receiver be used.

Install the main receiver using the same method you 

would use to install a conventional receiver in your 

aircraft. Typically wrap the main receiver in protective 

foam and fasten it in place using rubber bands or Velcro 

straps. Alternately in electric models or in jets (low 

vibration), it’s acceptable to use thick double-sided foam 

tape to fasten the main receiver in place.

Mounting the remote receiver(s) in a different 

location(s), from the primary receiver, gives tremendous 

improvements in path diversity. Essentially each receiver 

sees a different RF environment and this is the key to 

maintaining a solid RF link, even in aircraft that have 

substantial conductive materials, (i.e. Turbine engines 

with metal tail pipes, carbon fiber, tuned pipes, etc.) which 

can attenuate the signal.

Using double-sided foam tape, (servo tape) mount the 

remote receiver(s) keeping the remote antenna(s) at least 

2 inches away from the primary antenna. Ideally the 

antennas will be oriented perpendicular to each other; 

however, we’ve found this to not be critical. 6-inch, 

9-inch, 12-inch, 24-inch and 36-inch leads are available 

and in sophisticated aircraft, we’ve found it best to mount 

the remote receivers in different parts of the aircraft 

keeping the remote antennas as far away as practical from 

any conductive materials. A typical installation would 

include the main receiver mounted in the conventional 

location in the fuselage and the remote antennas in the 

nose (jets) in the top turtle deck and even in the tail. The 

optimum location is as far away from any conductive 

materials as practical.
G-18

In helicopters, there is generally enough room on 

the servo tray to achieve the necessary separation. If 

necessary, a mount can be made using clear plastic to 

mount the external antenna as shown below.

Other Important Installation Tips

1. The servos should be mounted using rubber grommets 

and brass eyelets to isolate them from vibration. Do 

not over-tighten the mounting screws; this will negate 

the vibration absorption effect of the rubber grommets. 

The following diagram will assist you in properly 

mounting your servo.

 The brass eyelets are pushed from the bottom up in the 

rubber grommets. When the servo screw is tightened 

securely, it provides the proper security as well as the 

proper vibration isolation for your servo.

2. The servos must be able to move freely over their 

entire range of travel. Make sure that the control 

linkages do not bind or impede the movement of any 

of the servos.

3. Mount all switches away from the engine exhaust and 

away from any high vibration areas. Make sure the 

switch operates freely and is able to operate over its 

full travel.

Model Match

The X9303 2.4 features patented ModelMatch technology 

that prevents the operation of a model if the wrong model 

memory is selected. During binding, the receiver actually 

learns and remembers the specific model memory (1 thru 

30) that the transmitter is currently programmed to. Later if 

the incorrect model memory in the transmitter is selected 

and the receiver is turned on, the model simply won’t 

operate, preventing a possible crash. Change programming 

to the correct model memory and you’re set to fly.

Servo Mounting Tab

Screw

Rubber Grommet

Brass Eyelet
G-19

It’s necessary to program the receiver to the transmitter 

so that the receiver will only recognize that specific 

transmitter, ignoring signals from any other sources. If the 

receiver is not bound to the transmitter, the system will 

not operate. During binding, the servo’s fail-safe positions 

are stored.

The following sequence describes the binding procedure 

for the JR R921, however, all JR and Spektrum DSM 

aircraft receivers are bound in the same way.

How To Bind

1. With the system hooked up as shown, insert the bind 

plug in the charge plug receptacle. The switch must be 

a 3-wire type switch (JRPA001 or JRPA004) to enter 

the bind mode through the switch. If a 3-wire switch is 

not available, install the male bind plug into the charge 

plug receptacle and power the receiver through any 

other open port to enter bind mode.

REMOVE BEFORE USE

2. Turn on the receiver switch. Note that the LED’s on 

all receivers should be flashing, indicating that the 

receiver is ready to bind.

AR9000

3. Establish the desired fail-safe stick positions: normally 

low throttle and flight controls neutral.

4. Press and hold the bind button on the back of the 

transmitter while turning on the power switch. The 

bind button should flash and within a few seconds the 

system should connect. The LED’s on the receivers 

should go solid, indicating the system has connected.

5. Remove the bind plug from the receiver or switch 

harness and store it in a convenient place.

6. After you’ve programmed your model, it’s important to 

rebind the system so the true low throttle and neutral 

control surface positions are programmed.

Note: To bind an aircraft with an electronic speed 

controller that powers the receiver through the 

throttle channel (BEC), insert the bind plug into the 

battery port and proceed to Step #2.

Binding
G-20

The JR R921 receiver features two types of fail-safe: 

SmartSafe and Preset Fail-safe.

SmartSafe

This type of fail-safe is especially ideal for most types of 

electric aircraft and is also recommended for most types 

of gas- and glow-powered airplanes and helicopters. 

Here’s how SmartSafe works.

Receiver Power Only

When the receiver only is turned on (no transmitter signal 

is present), all servos except for the throttle are driven to 

their preset fail-safe positions, normally control surfaces 

at neutral and the landing gear down. These fail-safe 

positions are stored in the receiver during binding. At this 

time the throttle channel has no output, to avoid operating 

or arming the electronic speed control. In glow-powered 

models, the throttle servo has no input so it remains in its 

current position.

After Connection

When the transmitter is turned on and after the receiver 

connects to the transmitter, normal control of all channels 

occurs. After the system makes a connection, if loss of 

signal occurs, SmartSafe drives the throttle servo only 

to its preset fail-safe position (low throttle) that was set 

during binding. All other channels hold their last position. 

When the signal is regained, the system immediately (less 

than 4 ms) regains control.

Preset Fail-Safe

Preset fail-safe is ideal for sailplanes and is preferred by 

some modelers for their glow- and gas-powered aircraft.

Receiver Power Only

When the receiver only is turned on (no transmitter signal 

is present) all servos except for the throttle are driven to 

their preset fail-safe positions, normally control surfaces 

at neutral and the landing gear down. These fail-safe 

positions are stored in the receiver during binding. At this 

time the throttle channel has no output, to avoid operating 

or arming the electronic speed control. In glow-powered 

models, the throttle servo has no input so it remains in its 

current position.

After Connection

When the transmitter is turned on and after the receiver 

connects to the transmitter, normal control of all 

channels occurs. After the system makes a connection, 

if loss of signal occurs preset fail-safe drives all servos 

to their preset fail-safe positions. For sailplanes, 

it’s recommended that the spoilers/flaps deploy to 

de-thermalize the aircraft, preventing a flyaway. Some 

powered modelers prefer to use this fail-safe system to 

program a slight turn and low throttle to prevent their 

aircraft from flying away. When the signal is regained, the 

system immediately (in less than 4 ms regains control).

Programming SmartSafe

(All Spektrum Aircraft Receivers)

During the binding process the bind plug is left in 

throughout the process and is removed only after the 

receiver connects to the transmitter. After the connection 

is made, confirmed by operating the servos, the bind plug 

can be removed. The receiver is now programmed for 

SmartSafe.

Fail-Safe Functions
G-21

(JR R921 and Spektrum AR 9000 Receivers Only)

During the binding process, the bind plug is inserted 

in the bind port or in the charge jack, then the receiver 

is powered up. The LED’s in each receiver should blink, 

indicating that the receiver is in bind mode. Now before 

binding the receiver to the transmitter and with the 

receiver in bind mode, remove the bind plug. The 

LED’s will still be blinking. With the control sticks and 

switches in the desired fail-safe positions, bind the 

transmitter to the receiver by pressing and holding the 

bind buttons on the back of the transmitter/module and 

turning on the transmitter. The system should connect in 

less than 15 seconds. The receiver is now programmed 

for preset fail-safe.

Note: Fail-safe positions are stored via the stick and 

switch positions on the transmitter during binding.

Standard Range Testing

Before each flying session, and especially with a new 

model, it’s important to perform a range check. The X9303 

2.4 incorporates a range testing system which, when 

the bind button on the transmitter is pressed and held, 

reduces the output power, allowing a range check.

Range Testing the X9303 2.4

1SFTTBOEIPMEUIFCJOECVUUPO

QBDFT	GFFU


1. With the model resting on the ground, stand 30 paces 

(approx. 90 feet) away from the model.

2. Face the model with the transmitter in your normal 

flying position and depress and hold the bind button 

on the back of the transmitter. This causes reduced 

power output from the transmitter.

3. You should have total control of the model with the 

button depressed at 30 paces (90 feet).

4. If control issues exist, call the JR Service Center at 

1-877-504-0233 for further assistance.

Programming Preset Fail-Safe
G-22

While the above Standard Range Testing procedure is 

recommended for most sport aircraft, for sophisticated 

aircraft that contain significant amounts of conductive/

reflective materials (i.e. turbine-powered jets, some types 

of scale aircraft, aircraft with carbon fuselages, etc.) the 

following advanced range check will confirm that all 

internal and remote receivers are operating optimally and 

that the installation (position of the receivers) is optimized 

for the specific aircraft. This Advanced Range Check 

allows the RF performance of each individual internal 

and remote receiver to be evaluated and to optimize the 

locations of each individual remote receiver.

Advanced Range Testing the X9303 2.4

1. Plug a flight log (optional) into the data port in the JR 

R921 receiver and turn on the system (transmitter and 

receiver).

2. Advance the Flight Log until F- frame losses are 

displayed, by pressing the button on the flight log.

3. Have a helper hold your aircraft while he observes the 

Flight Log data.

4. Standing 30 paces away from the model, face the 

model with the transmitter in your normal flying 

position and depress and hold the bind button on the 

back of the transmitter. This causes reduced power 

output from the transmitter.

5. Have your helper position the model in various 

orientations (nose up, nose down, nose toward the 

transmitter, nose away from the transmitter, etc.) 

while your helper is watching the Flight Log, noting 

any correlation between the aircraft’s orientation and 

Frame Losses. Do this for 1 minute. The timer on 

the X9303 can be used here. For giant-scale aircraft, 

it’s recommended that the airplane be tipped up on 

its nose and rotated 360 degrees for one minute, 

then record the data. Next place the airplane on its 

wheels and do a second test, rotating the aircraft in all 

directions for one minute.

6. After one minute, release the bind button. A successful 

range check will have recorded zero frame losses. 

Scrolling the Flight Log through the Antenna fades 

(A, B, L, R) allow you to evaluate the performance 

of each receiver. Antenna fades should be relatively 

uniform. If a specific antenna is experiencing a high 

degree of fades, then that antenna should be moved 

to a different location.

7. A successful Advanced test will yield the following:

H- 0 holds

F- 0 frame losses

A, B, R, L- Antenna fades will typically be less than 100. 

It’s important to compare the relative antenna fades and 

if a particular receiver has a significantly higher antenna 

fades (2 to 3X), then the test should be redone, and if 

the same results occur, move the offending receiver to a 

different location.

Advanced Range Testing Using a Flight Log
G-23

The Flight Log is compatible with JR R921 receivers. The 

Flight Log displays overall RF link performance as well 

as the individual internal and external receiver link data. 

Additionally it displays receiver voltage.

Using the Flight Log

After a flight and before turning off the receiver or 

transmitter, plug the Flight Log into the Data port on the 

JR R921 receiver. The screen will automatically display 

voltage i.e. 6v2= 6.2 volts.

Note: When the voltage reaches 4.8 volts or less, 

the screen will flash indicating low voltage.

Press the button to display the following information:

A - Antenna fades on internal antenna A

B - Antenna fades on internal antenna B

L - Antenna fades on the left external antenna

R - Antenna fades on the right external antenna

F - Frame loss

H - Holds

Antenna fades—represents the loss of a bit of information 

on that specific antenna.

Typically it’s normal to have as many as 50 to 100 antenna 

fades during a flight.

If any single antenna experiences over 500 fades in a 

single flight, the antenna should be repositioned in the 

aircraft to optimize the RF link.

Frame loss—represents simultaneous antenna fades 

on all attached receivers. If the RF link is performing 

optimally, frame losses per flight should be less that 20.

A hold occurs when 45 continuous (one right after the 

other) frame losses occur.

This takes about one second. If a hold occurs during a 

flight, it’s important to re-evaluate the system, moving the 

antennas to different locations and/or checking to be sure 

the transmitter and receivers are all working correctly.

Note: A servo extension can be used to allow the 

Flight Log to more conveniently be plugged in without 

having to remove the aircraft’s hatch or canopy. On 

some models, the Flight Log can be plugged in, 

attached and left on the model using double-sided 

tape. This is common with helicopters, mounting the 

Flight Log conveniently to the side frame.

Flight Log—Optional for JR R921 Receiver
G-24

With all radio installations, it is vital that the onboard 

power system provides adequate power without 

interruption to the receiver even when the system is fully 

loaded (servos at maximum flight loads). This becomes 

especially critical with giant-scale models that utilize 

multiple high torque/ high current servos. Inadequate 

power systems that are unable to provide the necessary 

minimum voltage to the receiver during flight loads have 

become the number one cause of in-flight failures. Some 

of the power system components that affect the ability 

to properly deliver adequate power include: the selected 

receiver battery pack (number of cells, capacity, cell type, 

state of charge), switch harness, battery leads, regulator 

(if used), power bus (if used).

While the R921 receivers’ minimum operational voltage is 

3.5-volts, it is highly recommended the system be tested 

per the guidelines below to a minimum acceptable voltage 

of 4.8-volts during ground testing. This will provide head 

room to compensate for battery discharging or if the 

actual flight loads are greater than the ground test loads.

Recommended Power System Guidelines

1. When setting up large or complex aircraft with multiple 

high torque servos, it’s highly recommended a current 

and voltmeter (Hangar 9 HAN172) be used. Plug the 

voltmeter in an open channel port in the receiver and 

with the system on, load the control surfaces (apply 

pressure with your hand) while monitoring the voltage 

at the receiver. The voltage should remain above 

4.8 volts even when all servos are heavily loaded.

Note: The optional Flight Log has a built in 

voltmeter and it can be used to perform this test.

2. With the current meter inline with the receiver battery 

lead, load the control surfaces (apply pressure 

with your hand) while monitoring the current. The 

maximum continuous recommended current for a 

single heavy-duty servo/battery lead is three amps 

while short duration current spikes of up to five amps 

are acceptable. Consequently, if your system draws 

more than three amps continuous or five amps for 

short durations, a single battery pack with a single 

switch harness plugged into the receiver for power 

will be inadequate. It will be necessary to use multiple 

packs of the same capacity with multiple switches and 

multiple leads plugged into the receiver.

3. If using a regulator, it’s important that the above 

tests are done for an extended period of 5 minutes. 

When current passes through a regulator, heat is 

generated and this heat causes the regulator to 

increase resistance, which in turn causes even more 

heat to build up (thermal runaway). While a regulator 

may provide adequate power for a short duration, it’s 

important to test its ability over time as the regulator 

may not be able to maintain voltage at significant 

power levels.

4. For really large aircraft or complex models (for 

example 35% and larger or jets), multiple battery 

packs with multiple switch harnesses are necessary 

or, in many cases, one of the commercially available 

power boxes/ busses is recommended. No matter 

what power systems you choose, always carry out test 

#1 above making sure that the receiver is constantly 

provided with 4.8 volts or more under all conditions.

5. The latest generation of Nickel Metal Hydride batteries 

incorporate a new chemistry mandated to be more 

environmentally friendly. These batteries, when 

charged with peak detection fast chargers, have 

tendencies to false peak (not fully charge) repeatedly. 

These include all brands of Ni-MH batteries. If using 

Ni-MH packs, be especially cautious when charging 

making absolutely sure that the battery is fully 

charged. It is recommended to use a charger that can 

display total charge capacity. Note the number of mAh 

put into a discharged pack to verify it has been charged 

to full capacity.

Receiver Power System Requirements
G-25

All preprogrammed data is protected by a flash 

memory that guards against memory loss main 

transmitter battery failure.

Flash Memory

Battery Alarm and Display

When the transmitter voltage drops below 9.0 volts DC, 

the display flashes “BATT LOW” and an alarm sounds.

If you are flying when this occurs, land immediately.

Tip on Using 2.4GHz Systems

While your DSM equipped 2.4GHz system is intuitive to 

operate, functioning nearly identically to 72MHz systems, 

following are a few common questions from customers:

1. Q: Which do I turn on first, the transmitter or the 

receiver?

 A: If the receiver is turned on first, all servos except 

for the throttle will be driven to their preset fail-safe 

positions set during binding. At this time, the throttle 

channel doesn’t put out a pulse position preventing 

the arming of electronic speed controllers or, in the 

case of an engine-powered aircraft, the throttle servo 

remains in its current position. When the transmitter is 

then turned on, the transmitter scans the 2.4GHz band 

and acquires two open channels. Then the receiver that 

was previously bound to the transmitter scan the band 

and finds the GUID (Globally Unique Identifier code) 

stored during binding. The system then connects and 

operates normally.

 If the transmitter is turned on first, the transmitter 

scans the 2.4GHz band and acquires two open 

channels. When the receiver is then turned on for a 

short period (the time it takes to connect), all servos 

except for the throttle are driven to their preset 

fail-safe positions while the throttle has no output 

pulse; The receiver scans the 2.4GHz band looking 

for the previously stored GUID; and when it locates 

the specific GUID code and confirms uncorrupted 

repeatable packet information the system connects and 

normal operation takes place. Typically this takes 2 to 

6 seconds.

2. Q: Sometimes the system takes longer to connect and 

sometimes it doesn’t connect at all?

 A: In order for the system to connect (after the receiver 

is bound) the receiver must receive a large number of 

continuous (one after the other) uninterrupted perfect 

packets from the transmitter in order to connect. This 

process is purposely critical of the environment, 

ensuring that it’s safe to fly when the system does 

connect. If the transmitter is too close to the receiver 

(less that 4 feet) or if the transmitter is located near 

metal objects (metal transmitter case, the bed of a truck, 

the top of a metal work bench, etc.) connection will take 

longer, and in some cases, connection will not occur 

as the system is receiving reflected 2.4GHz energy 

from itself and is interpreting this and unfriendly noise. 

Moving the system away from metal objects or moving 

the transmitter away from the receiver and powering 

the system up again will cause a connection to occur. 

This only happens during the initial connection. Once 

connected, the system is locked-in and, should a 

loss of signal occur (fail-safe), the system connects 

immediately (4ms) when signal is regained.
G-26

3. Q: I’ve heard that the DSM system is less tolerant of 

low voltage. Is that correct?

 A: All DSM receivers have an operational voltage range 

of 3.5 to 9 volts. With most systems, this is not a 

problem as most servos cease to operate at around 

3.8 volts. When using multiple high current draw 

servos with a single or inadequate battery/power 

source, heavy momentary loads can cause the 

voltage to dip below this 3.5-volt threshold, causing 

the entire system (servos and receiver) to brown 

out. When the voltage drops below the low voltage 

threshold (3.5 volts), the DSM receiver must reboot 

(go through the start-up process of scanning the band 

and finding the transmitter) and this can take several 

seconds. Please read the receiver power requirement 

on page G-24 as this explains how to test for and 

prevent this occurrence.

4. Q: Sometimes my receiver loses its bind and won’t 

connect, requiring rebinding. What happens if the bind 

is lost in flight?

 A: The receiver will never lose its bind unless it’s 

instructed to. It’s important to understand that during 

the binding process the receiver not only learns the 

GUID (code) of the transmitter but the transmitter 

learns and stores the type of receiver that it’s bound to. 

If the bind button on the transmitter is pressed at any 

time and the transmitter is turned on, the transmitter 

looks for the binding protocol signal from a receiver. 

If no signal is present, the transmitter no longer has 

the correct information to connect to a specific receiver 

and in essence the transmitter has been “unbound” 

from the receiver. We’ve had several customers that 

use transmitter stands or trays that unknowingly 

depress the bind button and the system is then turned 

on, losing the necessary information to allow the 

connection to take place. We’ve also had customers 

that didn’t fully understand the range test process 

and pushed the bind button before turning on the 

transmitter, also causing the system to “lose its bind.” 

If, when turning on, the system fails to connect, one of 

the following has occurred:

• The wrong model has been selected in the model 

memory (Model Match).

• The transmitter is near conductive material 

(transmitter case, truck bed, etc.) and the reflected 

2.4GHz energy is preventing the system from 

connecting (see #2 above).

• The bind button was unknowingly (or knowingly) 

depressed and the transmitter was turned on 

previously, causing the transmitter to no longer 

recognize the receiver.

5. Q: Can I use a 3-cell Li-Po pack in my transmitter

 A: No. All current JR and Spektrum transmitters are 

designed to operate using a 9.6-volt transmitter pack. 

A fully charged 3-cell Li-Po pack puts out 12.6 volts. 

This higher voltage can overload the power-regulating 

transistor causing damage and or failure, possibly 

in flight. Many of our customers have experienced 

failures using 3-cell Li-Po packs and their use in JR 

and Spektrum transmitters is highly advised against. 

The X9303 2.4 system will operate for over 15 hours 

using a 2700mAh Ni-MH battery.

6. Q: How important is it that I test my system using a 

flight log?

 A: For most sport airplanes and helicopters, the use 

of the flight log is unnecessary. For sophisticated 

aircraft, especially those that have significant 

conductive materials within the airframe (i.e. jets, 

scale airplanes, etc.), the Flight Log offers an extra 

measure of confidence that all radio components are 

working optimally. The Flight Log is an important 

tool that allows the confirmation that the installation 

(position of the internal and remote receivers relative 

to the conductive materials in the aircraft) is optimized 

and that the RF (radio) link is operating at the highest 

levels of performance.

Tip on Using 2.4GHz Systems (continued)
A-1

AIRPLANE – ACRO MODE

The ACRO mode of the X9303 2.4 system is intended for 

powered fixed-wing aircraft. It contains a host of advanced 

features that are easy to set up and use, and are designed 

to assist the pilot in realizing the full potential of the 

aircraft. These features include:

• Switch Assignments

• Flight Modes (3)

• Dual Rates/Exponential (2 or 3 sets for Aileron, 

Elevator and Rudder)

• Wing Type (Normal, Flaperon, Delta)

• Aileron Differential

• V-Tail

• Dual Channels for All Primary Flight Controls

and Flaps

• Dual Throttles (With Independent Trims and 

Throttle Curves)

• Adjustable Trim Rates (10–100 Trim Steps)

• Elevator-to-Flap Mixing

• Aileron-to-Rudder Mixing

• Throttle Curves (2)

• Flap System (With Elevator Trim, Auto Land, 

Elevator/Flap Delay)

• Snap Roll System (4 Directions/Rates Assigned to 

Flight Modes)

• Gyro System (In-Flight Gain Selection of 3 Gains 

for up to 2 Gyros)

• Servo Speed (Independent in Both Directions 

– Eliminates Door Sequencers)

• 6 Programmable Mixers (Includes 2 Multi-Point 

Mixers)

• Fail-Safe (Hold or Predetermined Positions)

• Trainer System (Selectable Channels for Student 

Control)

• Timers (Stopwatch, Countdown, Integrated)

• Servo Monitor (Automatically Renames Channels 

According to Assignments)

In addition to the numerous features listed above, the 

X9303 2.4 provides the ability to combine these features 

during flight, using a single Flight Mode switch. This 

capability dramatically reduces the pilot’s work load, 

allowing the pilot to concentrate on flying the aircraft 

instead of worrying about how to operate the transmitter.

Flight Modes

The X9303 2.4 provides the ability to combine many of the 

above functions during flight, using a single Flight Mode 

switch. This capability dramatically reduces the pilot’s 

work load, allowing the pilot to concentrate on flying the 

aircraft instead of worrying about specific switch positions.

ACRO PROGRAMMING - PLEASE 

READ

The X9303 2.4 menus and functions are presented in 

the recommended order that they should be addressed 

when setting up a new aircraft. Programming begins with 

entering the SYSTEM Menu, selecting a model, activating 

the ACRO mode, then progresses through the remainder 

of the SYSTEM Menu options, and then through the 

individual function mode programs. The descriptions are 

general in nature and provide the necessary information to 

identify the purpose of a function, allowing you to decide 

whether the function is appropriate for your application. 

Also included is specific information on making 

programming adjustments. 

ACRO - GETTING STARTED – SYSTEM 

MENU BASICS

Programming a new model begins by accessing the 

SYSTEM Menu. This is where models are selected, the 

mode is identified and where other high-level information 

is programmed about the model. It is also used to activate 

some of the more advanced programming features such 

as Flight Modes, Switch Assignments, Wing Type and 

Dual Control information.
ACCESS THE SYSTEM MENU

A-2

The first thing to do when setting up a new model is to 

select the desired model memory. Generally an unused 

model memory is selected, however, memory that already 

contains data for another model may be used, as long 

as data for that model is no longer required because any 

data in that memory will be lost.

1. In the SYSTEM Menu, highlight and select Model 

SEL using the Selector. The currently selected model 

number is displayed. If a different model is to be 

selected, highlight and select the displayed model and 

a list of models will appear. Scroll up and down the list 

using the Selector.

2. Use the Selector to highlight and select the desired 

model memory.

3. Return to the SYSTEM Menu by pressing the LIST button.

1. The System menu [SYSTEM M.] is obtained by 

holding down the ENT button while turning the 

transmitter on.

SELECT A MODEL MEMORY

INFO-DISP

Model SEL

MDL Name

Type SEL

MDL Reset

TRANSFER

TRIM STEP

Devic. SEL

Wing TYPE

[SYSTEM M.]

Select

 MODEL 2 ACRO

[Model SEL]

Select

 1 GLID 

MODEL 2 MODEL 2 ACRO 

 3 ACRO 

 4 GLID 

[Model SEL]
RESET THE MODEL

A-3

When setting up a new model it is important to reset 

all parameters to their default or factory settings before 

proceeding with any other programming. This is to ensure 

that there are no program mixes, trims or other functions 

left over from a previous model or programming session. 

1. In the SYSTEM Menu, highlight and select MDL 

Reset using the Selector.

2. Press the CLR button that is next to RES

on the display.

3. Press the lowermost button next to YES on the display 

to reset all data for this model.

4. Return to the SYSTEM Menu by pressing

the LIST button.

[MDL Reset]

LST

RES

MODEL 2 ACRO

[MDL Reset]

LST

YES

NO

MODEL 2 ACRO

Are you sure? Y/N
TO ACTIVATE THE ACRO MODE

ENTER A NAME FOR THE MODEL

A-4

After selecting and resetting a model memory, it is 

necessary to program the transmitter to ACRO.

1. In the SYSTEM Menu, highlight and select Type 

SEL using the Selector.

2. Highlight and select ACRO using the Selector.

3. Return to the SYSTEM Menu by pressing

the LIST button.

Each model should be named allowing for easy 

identification in the model memory list and on the main 

display screen. The model name appears in the upper 

right-hand corner of the main screen when the transmitter 

is switched on.

1. In the SYSTEM Menu, highlight and select MDL 

Name using the Selector.

2. The cursor (the triangle that indicates where the next 

character will be placed), is positioned at the beginning 

of the model name. Press the Selector to obtain a list 

of available characters.

3. Highlight and select the desired character to create 

the model name. After a character is selected, rotate 

the Selector to position the cursor where the next 

character is to be placed and press the Selector to 

obtain the character list again. Repeat until the model 

name is completed.

4. Return to the SYSTEM Menu by pressing the LIST button.

[Type SEL] MODEL 2 ACRO

GLID ACRO HELI

 MODEL 3 ACRO <H9 EXTRA>

[MDL Name]

 !"#$%'()*+,-./01234567

89;:<=>?@ABCDFGHIJKLMNO

PQRSTUVWXYZ[ ]^_`abcdefg

hijklmnopqrstuvwxyz{|}~
A-5

Device SEL and Wing Type are two powerful functions 

in the SYSTEM Menu that control some of the more 

advanced features of the X9303 2.4 system. The Device 

SEL function is used to activate/inhibit Flight Modes; 

change switch assignments; activate/inhibit switches/

channels; and to activate the FLAP TRIM lever that is next 

to the FLAP switch on the transmitter.

The Wing Type function is used to indicate the wing 

type (Normal, Flaperon, Delta); to program the aircrafts 

tail configuration; and to identify any dual channels for 

primary flight controls (ELEV, AILE, RUDD, FLAP). Wing 

Type also provides for a 2nd throttle channel, complete 

with independent trim and throttle curves to accommodate 

twin-engine aircraft.

ACRO - SYSTEM MENU - ADVANCED FUNCTIONS
FLIGHT MODES

A-6

landing speeds and again have a lot of Exponential on 

the rudder to prevent over-steering upon the landing/roll 

out. A couple of program mixes can be set up to bring 

in some Up-Elevator to make the jet assume a positive 

angle of attack, and to deploy the speed brakes. The 

two mixers can then be assigned only to the 3rd Flight 

Mode for landings. The Landing flap position can also be 

associated with the 3rd or Landing Flight Mode and the 

Gyro gain can again be turned-on to assist in a straight 

roll-out during landing.

Many of the functions found in the X9303 2.4 system 

are switch selectable (including programmable mixers) 

and can be assigned to one or more Flight Modes. This 

provides the ability to have 3 completely different aircraft 

configurations that are selectable in flight using a 

single switch.

Three Flight Modes are available in the X9303 2.4 system. 

When Flight Modes are activated, they are selected during 

flight by using one of the two 3-position switches (FLAP 

Switch or AUX2 switch). The pilot decides which switch is 

to be used when Flight Modes are activated in the Devic. 

SEL function in the System menu. Once Flight Modes 

are activated, the pilot has a choice of using the Flight 

Mode switch to select up to 3 Dual Rates and Exponential 

settings for each of the primary controls (ELEV, AILE, 

RUDD), or Dual Rates and Exponential settings may 

continue to be controlled by the 3 individual Dual Rate 

switches. However, when using the standard D/R switches, 

there are only 2 settings possible for each of the primary 

controls because the D/R switches are only 2-position 

switches. All other functions that can be activated by a 

switch can be assigned to 1 or more Flight Modes when 

Flight Modes have been activated.

Decide if Flight Modes are to be activated. If 

3 sets of Dual Rates and Exponential settings are 

desired for Elevator, Ailerons, and Rudder instead of 

having only 2 sets available, then continue below to 

activate Flight Modes.

If there is a desire to gang Dual Rates for Aileron, Elevator 

and Rudder together on a single switch, then continue 

below to activate Flight Modes.

If there is a need to group multiple functions together 

in order to perform certain tasks with the aircraft, then 

continue below to activate Flight Modes. If it is decided 

that Flight Modes are not to be activated, then skip to 

SWITCH ASSIGNMENTS below. 

A Flight Mode represents an aircraft configuration (Dual 

Rate/Expo, programmed mixes, Aileron Differential, Flap 

System, Gyro System, etc.) that is designed and optimized 

to assist the pilot and the aircraft in performing a specific 

type of maneuver.

The objective of programming Flight Modes is to provide 

the ability to flip a switch to select a collection of settings 

that are optimized to perform a maneuver. An aerobatic 

aircraft, for example, may be set up such that the Flight 

Mode switch in its 1st position configures the aircraft 

for normal precision flying; positioning the switch in 

its 2nd position sets the aircraft up for snap rolls; and 

positioning the switch in its 3rd position sets the aircraft 

up for consecutive rolls, slow rolls, and rolling circles. 

The 3 Flight Modes could just as easily represent aircraft 

settings for Take Off, Flying, and Landing for a turbinepowered jet aircraft. The point being that Flight Modes 

can make the pilot’s job easier by configuring the aircraft 

to do different things by flipping a single switch.

For example, let’s consider a jet aircraft and how Flight 

Modes might be used to make the pilot’s job easier. The 

jet will utilize 3 Flight Modes - 1 for takeoffs, 1 for flying 

at high speed and 1 for landing. 

During takeoff, full control deflections are desired, with a 

moderate amount of Exponential to assist in rotation and 

control of the aircraft at takeoff speed. Steering should 

have a lot of Exponential to avoid over-steering during 

the takeoff roll. So for the 1st Flight Mode (FM0), Dual 

Rates and Exponential curves are set for Ailerons and 

Elevator to allow adequate control for rotation and control 

at takeoff speed, while a high percentage of Exponential 

is set for the rudder/steering to help prevent over-steering 

during take off. If the aircraft is equipped with 3 position 

Flaps (Retracted, Take-off position and Landing position), 

the Take-off flap position can be assigned to only the 1st 

Flight Mode to assist in takeoff. There may also be a Gyro 

attached to the steering/rudder and the Gyro gain can be 

turned-on and associated with the Take-Off Flight Mode 

to assist in keeping the aircraft straight during the takeoff 

roll.

For normal flight at higher speeds, the 2nd Flight Mode 

(FM1) would be set up to have quite a bit of Exponential 

and perhaps reduced control rates on all control surfaces 

because a lot less control deflection is required at 

high speeds. The retracted flap position would also be 

assigned to this Flight Mode and the Gyro gain could be 

reduced or turned-off.

For landing, the 3rd Flight Mode (FM2) would be set 

up to use full control throws with a moderate to high 

degree of Exponential to smoothly control the jet at lower 
To Activate Flight Modes

A-7

1. From SYSTEM M. highlight and select Devic. SEL

using the Selector.

2. Using the Selector, highlight and select INH under 

FLIGHT MODE. When selected, two options appear: 

AUX2 SW and FLAP SW. Highlight and select 

the switch that is to be used to select between Flight 

Modes while flying. The example below shows that the 

FLAP switch has been selected.

Once Flight Modes have been activated, 2 new parameters 

appear on the display: TRIM:COM and D/R:SW. 

Once one of the 3-position switches is selected, Flight 

Mode 0 (FM0) is in effect when the switch is in the 

upper position, Flight Mode 1 (FM1) is in effect when 

the switch is in the middle position and Flight Mode 

2 (FM2) is in effect when the switch is moved to the 

lowest position.

[Devic. SEL]

FLIGHT MODE

INH GEAR FLAP AUX2 AUX3 AUX4

GEAR FLAP AUX2 AUX3 RUDD

 SW SW SW LEV D/R

OUT: INH ACT ACT INH ACT

TRIM OFF

[Devic. SEL]

FLIGHT MODE

INH GEAR FLAP AUX2 AUX3 AUX4

GEAR FLAP AUX2 AUX3 RUDD

 SW SW SW LEV D/R

OUT: INH ACT ACT INH ACT

TRIM OFF

INH

AUX2 SW

FLAP SW
TRIM:COM (Flight Modes)

D/R:SW (Flight Modes)

A-8

The TRIM:COM parameter can be toggled back and 

forth between COM and FM by pressing the Selector 

when COM or FM is highlighted. If left in the COM 

mode, the digital trims for Elevator, Ailerons, and Rudder 

are Common or shared by the 3 Flight Modes. If FM 

is selected, the X9303 2.4 keeps track of the digital 

trims independently for each Flight Mode, which means 

the pilot can re-trim the aircraft using the digital trims 

for each Flight Mode. This is a very useful feature if 

switching between Flight Modes causes the aircraft’s trim 

to change, such as when flaps are deployed by one of 

the Flight Modes causing a slight roll. In this case, the 

pilot can simply use the Aileron digital trim to trim the 

Ailerons, eliminating the roll tendency when that Flight 

Mode is selected. Selecting other Flight Modes brings in 

a corresponding set of trims, ensuring the aircraft stays 

in trim as the pilot changes between the 3 Flight Modes 

during flight.

If Flight Modes are only going to be used to switch 

between 3 sets of Dual Rates/Exponential settings, then 

leave the TRIM parameter set to COM. If other functions 

are to be controlled by Flight Modes which may have a 

tendency to cause the aircraft trim to change, then select 

FM for the TRIM parameter. The example below shows 

FM selected, meaning that each Flight Mode has its own 

set of trims. The setting can be changed at any time by 

returning to this display.

Note: When trims are set to FM, be especially 

careful during the first flight of an aircraft to 

remember that the aircraft will need to be trimmed 

using the digital trims for Aileron, Elevator and 

Rudder for each Flight Mode selected during flight. 

If the aircraft is badly out of trim, it will probably be 

badly out of trim for each Flight Mode selected. If the 

out-of-trim condition is very severe, it might be wise 

to land after trimming the first Flight Mode and then 

note the trim settings. Switch to the other 2 Flight 

Modes and match the trims to these settings before 

flying again. 

The D/R:SW parameter may be toggled between SW 

and FM by pressing the Selector when SW or FM is 

highlighted. If left in the SW mode, then the 3 Dual Rate 

switches will be used to select Dual Rates and Exponential 

settings for Elevator, Ailerons, and Rudder and there 

will only be 2 sets of Dual Rates/Expo settings for each 

control. If FM is selected, the Flight Mode switch will 

be used to select Dual Rates/Expo settings for all three 

controls at once (Elev, Aile, Rudd - D/R settings ganged 

together on the Flight Mode switch) and there will be 3 

sets of D/R/Expo values available for each control.

If individual D/R switches (3 switches) to control only 2 

sets of rates and curves for Elevator, Ailerons and Rudder 

are desired, set this parameter to SW. If 3 sets of rates and 

curves that are selectable by a single Flight Mode switch 

are desired, then set this parameter to FM. This setting 

may be changed at any time by returning to this display.

[Devic. SEL]

FLIGHT MODE

FLAP SW GEAR FLAP AUX2 AUX3 AUX4

GEAR FLAP AUX2 AUX3 RUDD

 SW SW SW LEV D/R

OUT: INH ACT ACT INH ACT

TRIM OFF

TRIM:FM

D/R:FM
SWITCH ASSIGNMENTS

FLAP TRIM ON/OFF

A-9

The X9303 2.4 provides the ability to change the standard 

default switch assignments for GEAR, FLAP, AUX2, AUX3, 

and AUX4. The standard switch assignments may be 

changed in the Devic.SEL function contained in the SYSTEM 

Menu. To change one or more switch assignments:

1. From within the Devic.SEL function, use the Selector 

to highlight and select GEAR, FLAP, AUX2, AUX3, 

or AUX4 along the top line of the display.

2. Once a switch is selected, a list of available 

replacement switches is displayed. Highlight and select 

the desired switch with the Selector.

3. Repeat for as many switches as desired.

1. The digital FLAP TRIM lever is located next to the 

FLAP switch. It may be activated or deactivated in 

the Devic.SEL function by using the Selector to 

highlight either ON or OFF and pressing the Selector 

to toggle between these two values.

Ordinarily this switch should be turned OFF, 

even if the aircraft has flaps or flaperons, because the 

system provides other means of controlling flaps and 

disabling this switch will help prevent a serious out-oftrim condition if flaperons are used and the trim lever is 

accidentally moved. Do not turn this on unless there 

is a specific need to do so.

[Devic. SEL]

FLIGHT MODE

INH GEAR FLAP AUX2 AUX3 AUX4

GEAR FLAP AUX2 AUX3 RUDD

 SW SW SW LEV D/R

OUT: INH ACT ACT INH ACT

TRIM ON

AIL D/R AUX2 SW

ELE D/R FLAP SW

RUD D/R GEAR SW

MIX SW SNAP SW

[Devic. SEL]

FLIGHT MODE

FLAP SW GEAR FLAP AUX2 AUX3 AUX4

GEAR FLAP AUX2 AUX3 RUDD

 SW SW SW LEV D/R

OUT: INH ACT ACT INH ACT

TRIM OFF

TRIM:FM

D/R:FM
ACTIVATE/INHIBIT SWITCHES

A-10

The X9303 2.4 provides the ability to inhibit or otherwise 

disable a number of the levers and switches on the 

transmitter – GEAR, FLAP, AUX2, AUX3, and AUX4. This 

is very useful when auxiliary channels are used as dual 

primary flight controls, such as using 2 channels/servos 

for 2 Elevator halves and/or using 2 servos/channels to 

operate the Rudder. In this instance, the auxiliary channels 

are no longer to be operated by their auxiliary switches 

but rather by the Elevator and Rudder sticks. 

Note: If any of the channels identified above are to 

be used as a 2nd channel for a primary flight control 

(AILE, ELEV, RUDD, FLAP), then be sure to Inhibit 

(INH) the switches for the channels in this function 

or they will not be available to use as a second 

control channel.

1. If GEAR, FLAP, AUX2, AUX3, or AUX4 are to be 

used as a 2nd primary flight control, then inhibit the 

corresponding switch by highlighting either ACT, 

SYS. or GYRO along the bottom line of the display 

and pressing the Selector until INH appears under 

the switches that are to be turned off. The example 

below shows all switches as INH or being turned off, 

making them all available to be used as a 2nd channel 

for a primary flight control.

Note: When SYS appears under FLAP, the FLAP 

SYSTEM function will appear in the FUNC.LIST

(described later). If the aircraft is equipped with flaps, 

or equipped with Flaperons that are actually going to 

be used as flaps then SYS should be set under FLAP.

Note: When GYRO appears under AUX2 or AUX3, 

the Gyro Function will appear in the FUNC.LIST

(described later). If the aircraft is equipped with 

1 Gyro, then GYRO should be set under AUX2 or 

AUX3. If it is equipped with 2 gyros, then GYRO 

should be present under both AUX2 and AUX3. The 

gain lead/plug from the Gyro(s) is plugged into the 

AUX2 and/or AUX3 channels.

[Devic. SEL]

FLIGHT MODE

FLAP SW GEAR FLAP AUX2 AUX3 AUX4

GEAR FLAP AUX2 AUX3 RUDD

 SW SW SW LEV D/R

OUT: INH INH INH INH INH

TRIM OFF

TRIM:FM

D/R:FM
WING TYPE

A-11

The Wing Type function provides for 3 different wing types 

(NORMAL, FLAPERON and DELTA). NORMAL wing type 

is used when the Aileron channel is the only channel to be 

used to control ailerons, either with 1 servo, or multiple 

servos connected through a Y-harness to the aileron 

channel. It is also used when the aircraft is equipped with 

flaps that are separate from the ailerons. FLAPERON is 

typically used when Ailerons are controlled by separate 

servos that are on separate channels and there are 

no other flaps on the aircraft. DELTA is used when 

the Ailerons are used as both Ailerons and Elevators 

(Elevons) on an aircraft with a Delta wing configuration.

The Wing Type function also provides for aircraft that 

have a V-Tail configuration where the 2 Elevators are used 

for both Elevator and Rudder control. It also provides for 

instructing the transmitter to use one or more auxiliary 

channels as a 2nd or dual channel for primary flight 

controls (AILE, ELEV, RUDD, FLAP). Finally, the Wing 

Type function contains the Twin Engine (Twin E.) feature, 

which allows for setting up a 2nd throttle channel for a 

second engine, complete with its own trim and throttle 

curves – an excellent feature for twin-engine aircraft!

This is a very important function because a large 

number of sport and aerobatic aircraft use 2 servos 

and 2 channels to operate the Ailerons, providing the 

opportunity to utilize Aileron Differential to make rolls 

more axial and to couple Flaps with Elevator for very tight 

looping maneuvers and 3D flying. Unless the aircraft has 

separate flaps, the FLAPERON wing type should be used 

here, as all of the mixing is accomplished automatically 

by the transmitter. Setting the wing type to FLAPERON 

also makes available the Aileron Differential and 

Elevator-to-Flap mixing functions in the FUNC.LIST 

(described later).

If the aircraft has flaps that are separate from the Ailerons, 

then use the NORMAL wing type and use the Dual 

Channel feature to enable a 2nd Aileron channel if dual 

Aileron channels are desired.
WING Parameter – (Wing Type)

A-12

1. Highlight and select Wing TYPE in the SYSTEM 

Menu using the Selector.

2. If only the Aileron channel is to control both Ailerons, 

either with a single servo or with 2 servos connected 

together via a “Y” harness, then leave the Wing 

3. If 2 channels are to be used to control the Ailerons and 

the aircraft does not have separate flaps, highlight and 

select Wing with the Selector and then highlight 

and select FLAPERON as the wing type. Plug the 

right Aileron into the Aileron channel (Ch2) and plug 

the left Aileron servo into the FLAP or AUX1 channel 

(Ch6) of the receiver. 

parameter set to the default of NORMAL and plug 

the Aileron servo into the Aileron channel (Ch2) of the 

receiver. Also use NORMAL if the aircraft has flaps 

that are separate from the ailerons. 

Note: If the Ailerons are not going to actually be 

used as flaps, inhibit the FLAP Switch and FLAP 

TRIM in the Devic.SEL function in the SYSTEM 

Menu. This will eliminate having a severe out-oftrim condition if the FLAP Switch or FLAP TRIM is 

accidentally moved.

[WING TYPE]

Wing: NORMAL V-Tail: INH

Dual AILE ELEV RUDD FLAP MATE INH

Mate INH INH INH INH Trim -

Trim - - - - AUXT - 

TWIN E.

[WING TYPE]

Wing: FLAPERON V-Tail: INH

Dual AILE ELEV RUDD FLAP MATE INH

Mate INH INH INH INH Trim -

Trim - - - - AUXT - 

TWIN E.
WING Parameter – (Wing Type) (continued)

A-13

4. If the aircraft is a Delta wing configuration, highlight 

and select Wing using the Selector and then 

highlight and select DELTA as the wing type. Plug the 

right Aileron into the Aileron channel (Ch2) and plug 

the left Aileron into the Elevator channel (Ch3) of the 

receiver.

Note: To properly set the servo direction when 

using the delta wing setting, begin by using servo 

reversing on each channel as necessary to get the 

ailerons to move the proper direction with aileron 

stick movement. If then the ailerons move the 

incorrect direction with elevator stick movement, 

swap the channels that the servos are plugged into 

the receiver to reverse them.

[WING TYPE]

Wing: DELTA V-Tail: INH

Dual AILE ELEV RUDD FLAP MATE INH

Mate INH INH INH INH Trim -

Trim - - - - AUXT - 

TWIN E.
Dual Channels (Wing Type)

V-tail (Wing Type)

A-14

1. To assign a 2nd channel to Ailerons, Elevator, Rudder 

or Flaps, highlight and select INH under the desired 

channel on the Mate line of the Wing TYPE display 

and a list of available channels is displayed.

Note: Channels/Switches must be inhibited (INH) in 

the Devic. SEL function before they will appear in 

the list as an option to be used as a Dual channel.

1. If the aircraft has a V-tail configuration, highlight INH 

next to V-tail in the Wing TYPE function and press the 

Selector until ACT appears. Plug the right Elevator 

servo into the Elevator channel (Ch3) and plug the left 

Elevator servo into the Rudder channel (Ch4). Pressing 

the Selector toggles the parameter between ACT and 

INH. If the aircraft has a normal tail, make sure INH 

is selected and plug the Elevator and Rudder servos 

into the Elevator and Rudder channels (Ch3 and Ch4 

respectively). Continue with Dual Channels below.

Note: To properly set the servo direction when using 

the V-tail setting, begin by using servo reversing 

on each channel as necessary to get the elevators 

to move the proper direction with rudder stick 

movement. Then if the elevators move the incorrect 

direction with elevator stick movement, swap the 

channels that the servos are plugged into in the 

receiver to reverse them.

[WING TYPE]

Wing: NORMAL V-Tail: INH

Dual AILE ELEV RUDD FLAP MATE INH

Mate INH INH INH INH Trim -

Trim - - - - AUXT - 

TWIN E.

INH GEAR AUX2

 FLAP AUX3
V-tail (Wing Type) (continued)

A-15

2. Highlight and select the channel that is to be the Mate 

(slave) to the control channel represented above it. 

Plug the 2nd control surface servo into the channel 

selected as the Mate.

3. If FLAP or AUX3 is selected as a Mate, INH 

will appear on the Trim Line of the display directly 

beneath the channel just selected. This means that 

the corresponding digital switch (FLAP TRIM or 

AUX TRIM) located next to the FLAP and AUX2 

switches can be used as additional trims. However, 

the additional trims do not function in the 

same fashion as regular trims. Instead, they 

trim the controls such that both channels move in the 

same direction – like reflexing both Ailerons or in the 

case of Elevator halves, the Elevators would move in 

opposite directions. As a result, these additional 

trims should remain inhibited unless there 

is a special need for them. If changed to ACT, 

the corresponding trim switch (FLAP or AUX3) will 

become active. If set to INH these additional trim 

switches are inactive. Normal trims continue to work 

regardless of the settings.

[WING TYPE]

Wing: NORMAL V-Tail: INH

Dual AILE ELEV RUDD FLAP MATE INH

Mate INH AUX3 INH INH Trim -

Trim - INH - - AUXT - 

TWIN E.
Twin E. (Wing Type)

A-16

If the aircraft is equipped with twin engines, the Twin 

Engine feature (Twin E.) may be used for a 2nd throttle 

channel with an optional separate digital trim. The FLAP 

or AUX3 channel must be selected as the Mate for the 

additional trim to be available. If another channel is used 

as the Mate, the 2nd throttle channel can be trimmed by 

the regular throttle trim along with the throttle channel.

Note: Channels/Switches must be inhibited (INH) in 

the Devic. SEL function before they will appear in the 

list as an option to be used as a Twin Engine channel.

1. Highlight and select INH next to Mate under Twin 

E. A list of available channels will appear. Select the 

FLAP or AUX3 channel if a separate trim is desired 

for the 2nd throttle channel. You can select a different 

channel if an additional trim is not desired. The normal 

throttle trim can trim both channels at the same time. 

Plug the Left engine throttle servo into the channel 

selected as the Mate. Plug the Right engine throttle 

servo into the throttle channel (Ch 1).

2. If the second throttle channel is to be trimmed using 

either the normal throttle trim lever or a separate trim 

lever, highlight and select INH next to Trim under 

Twin E. causing the setting to change to ACT. 

Pressing the Selector toggles between INH and 

ACT. When set to ACT, the 2nd throttle servo can 

be trimmed with either the normal throttle trim or a 

separate trim if Flap or AUX3 is selected as the 2nd 

throttle channel.

Dual AILE ELEV RUDD FLAP MATE INH

Mate INH INH INH INH Trim -

Trim - - - - AUXT - 

[WING TYPE]

Wing: NORMAL V-Tail: INH

TWIN E.

INH GEAR AUX2

 FLAP AUX3

Dual AILE ELEV RUDD FLAP MATE AUX3

Mate INH INH INH INH Trim ACT

Trim - - - - AUXT - 

[WING TYPE]

Wing: NORMAL V-Tail: INH

TWIN E.
Twin E. (Wing Type) (continued)

A-17

3. If FLAP or AUX3 has been selected as the Mate and 

a separate digital trim is to be used for the 2nd throttle 

channel, Highlight and select INH next to AUXT. 

This changes the setting to ACT, enabling the digital 

trim that corresponds to the selected channel. The 

digital trim switches are next to the FLAP and AUX2 

switches on the transmitter.

Dual AILE ELEV RUDD FLAP MATE AUX3

Mate INH INH INH INH Trim ACT

Trim - - - - AUXT ACT 

[WING TYPE]

Wing: NORMAL V-Tail: INH

TWIN E.
TRIM STEP

A-18

The Trim Step function provides for adjusting the 

sensitivity of the X9303 2.4 trim levers and switches. It is 

useful during and after initial trimming of the aircraft, in 

order to trim the aircraft quickly at first and then to make 

very precise adjustments to aircraft trim. The digital trims 

may have a setting of 0–10 with 10 being the coarsest 

adjustment. When the value is set to 10, there are only 

10 trim increments from center to each end. When set to 

5, there are 20 trim increments from center to each end. 

When set to 4 there are 25 increments. When set to 3 

there are 34 increments and when set to 1 there are 100 

trim increments! When set to 0 the trim levers cease to 

function and can no longer be used to change the trim 

of the aircraft.

When adjusting the digital trims (AILE, ELEV, RUDD, 

FLAP, AUXT), the total trim travel does not change—only 

the number of increments (beeps) changes, which makes 

for finer or coarser trim movements. When adjusting 

the analog throttle trim, however, the total trim travel is 

actually reduced when set to less than 100%.

Use a fairly coarse setting such as 4–6 when test flying

an aircraft in order to be able to trim the aircraft quickly, 

and then use a finer setting such as 3–1 for final

precision trimming.

1. Highlight and select TRIM STEP in the SYSTEM

MENU to acquire the TRIM STEP display.

2. Highlight and select the trim that is to be changed 

and use the Selector to set a value of 1–10

(1 = finest, 10 = coarsest).

3. Repeat for other trims as desired.

This concludes the SYSTEM Menu portion of the ACRO 

mode. Continue with FUNC.LIST below to complete the 

aircraft setup.

[TRIM STEP]

THRO 100%

AILE 4

ELEV 4

RUDD 4

AUXT 4

FLAP 4
REV.SW – SERVO REVERSING 

A-19

Once the basic aircraft configuration has been defined in 

the SYSTEM Menu, the functions found in the Function 

List [FUNC.LIST] are used to complete the setup and 

then to adjust how the aircraft flies. The functions are 

presented (to the extent practical) in the order that they 

should be addressed when setting up a new aircraft. 

The descriptions are general in nature and are intended to 

provide enough information to decide whether or not to 

use a function and what types of selections and settings 

to make.

Press the LIST button after the transmitter is powered-up 

to obtain the FUNC.LIST.

Once all servos have been plugged into their proper 

channels in the receiver, the first thing to check is the 

direction of travel of each servo. Move all sticks and 

switches/levers while observing each servo to determine

if the servos are moving in the correct directions. Make 

note of those channels that are not traveling in the correct 

direction and use the REV.SW function to reverse the 

direction of travel for these channels.

1. Highlight and select REV.SW in the FUNC.LIST to 

obtain the servo reversing display.

2. Use the Selector to highlight and select those 

channels that need to be reversed. Pressing 

the Selector toggles the channel between 

Normal and Reverse.

ACRO – FUNCTION LIST

[REV SW.]

THR AIL ELE RUD GER FLP AX2 AX3 AX4

REV.

NORM

D/R & EXP

REV. SW

Sub Trim

TRVL ADJ.

ELE FLP M

AIL RUD M

THRO CURV

FLAP SYS.

Snap Roll

SRV. Speed

Prog. Mix1

Prog. Mix2

Prog. Mix3

Prog. Mix4

Prog. Mix5

Prog. Mix6

Trainer

TIMER

MONITOR

[FUNC. LIST]
SUB TRIM

A-20

Sub Trims are intended for relatively minor adjustments to 

servo linkages and not for major trim adjustments to the 

aircraft. Using excessive Sub Trim percentages can cause 

a loss of available servo travel where the servo reaches its 

travel limit and stops moving before the control sticks are 

fully deflected. For more information on Sub Trims and 

linkage setups, please refer to the Sub Trim Usage and 

Mechanical Advantage article contained in the Glossary.

Use Sub Trims to fine-tune the alignment of servo arms. 

Install servo arms on the servos so that the arms are at 

90 ̊ or perpendicular to the servo case/linkage. Rotate, 

swap and reinstall the arms or try different arms if 

necessary to get them as close to 90 ̊ as possible. It is not 

unusual for the arms to be off just a little bit. Now use the 

Sub Trim function to fine-tune the servo arms that are not 

quite at 90 ̊ to the linkage/servo case.

1. Highlight and select Sub Trim in the FUNC.LIST to 

obtain the Sub Trim Display.

2. Highlight and select the channels where the servo arms 

are not quite at 90 ̊ to the servo cases. Once a channel 

is selected, rotate the Selector until the servo arm is 

at 90 ̊ to the servo case.

[Sub Trim]

THRO 0 GEAR 0

AILE 0 FLAP 0

ELEV 16 AUX2 0

RUDD 0 AUX3 0

 AUX4 0
TRVL ADJ. – TRAVEL ADJUST

A-21

Travel Adjust is used to adjust how far a servo travels in 

each direction. After the linkages have been installed and 

attached to the servos, adjust the amount of servo travel in 

each direction. For more information on Servo Travel and 

Mechanical Advantage, please refer to the Sub Trim Usage 

and Mechanical Advantage article contained in the Glossary.

1. Highlight and select TRVL ADJ. in the FUNC.LIST

to obtain the Travel Adjust display.

2. Use the Selector to highlight and select each channel 

and adjust the travel in each direction by rotating the 

Selector. The direction of travel is changed by moving 

the stick/switch/lever back and forth.

[TRVL ADJ.]

THRO L100% R100% GEAR +100% -100%

AILE L100% R100% FLAP U100% D100%

ELEV D100% U100% AUX2 +100% -100%

RUDD L100% R100% AUX3 +100% -100%

 AUX4 +100% -100%
D/R & EXP – DUAL RATE AND EXPONENTIAL

A-22

Dual Rates and Exponential curves can be very effective 

in setting up an aircraft to have a particular “feel” when 

performing different types of maneuvers. Just flipping a 

switch can change the aircraft’s personality, causing it 

to take on traits that make certain maneuvers easier for 

the pilot. At times the aircraft needs to feel very crisp, 

such as when performing point-oriented aerobatics, and 

then feel softer for other maneuvers such as landing and 

rolling circles, and yet at other times the aircraft needs 

to be very crisp but without the tendency to be overcontrolled, like in performing snap rolls. Dual Rates and 

Exponential curves can be combined to produce these 

traits for most any aircraft. When programming a Dual 

Rate and Exponential curve, think about what kind of 

maneuver is to be performed and the response that is 

desired from the aircraft. For an in-depth description of 

D/R and Exponential, please refer to the Dual Rates and 

Exponential Curves at teh end of teh Aircraft section of 

this manual

1. Highlight and select D/R & EXP in the FUNC.LIST

to obtain the D/R & EXP display. If Flight Modes

were activated earlier in the Devic.SEL function and 

D/R was set to FM in the same function, there will 

be 3 sets of values displayed for each channel. 

Otherwise, there will only be 2 sets of Dual Rate and 

Exponential settings for each control.

2. Use the Selector to change between Aileron, Elevator 

and Rudder by highlighting and selecting AILE. Then 

use it to select and set dual rate and exponential 

values. If exponential has never been used before, try 

a low positive value like +10. After a while increase it 

gradually until the desired feel is obtained.

Note: Use only positive (+) percentages unless there 

is a distinct need to do otherwise.

D/R EXP

100% + 35%

100% + 35%

100% LIN

100% LIN

100% LIN

100% LIN

[D/R & EXP]◊0

F.M.0

F.M.1

F.M.2

AILE

OUTPUT

D/R EXP

100% + 35%

100% + 35%

 77% + 35%

 77% + 35%

100% LIN

100% LIN

[D/R & EXP]◊1

F.M.0

F.M.1

F.M.2

AILE

OUTPUT
THRO CURV – THROTTLE CURVE

A-23

A linear throttle response can be obtained with the THRO 

CURV function by causing the throttle servo to move in an 

exponential fashion. In other words, the servo will move 

very little for the first 1⁄4–1⁄2 of stick movement, and then 

move more rapidly as the stick is advanced further.

THRO CURV can also be used to set up a special throttle 

response where the engine quickly comes up to a certain 

rpm and then advances very slowly to provide precise rpm 

control for a specific throttle range before continuing on 

to full throttle. Such a curve is useful for torque rolling, 

rolling circles and other maneuvers where the throttle 

response is to be slowed or flattened-out for a particular 

throttle range.

If the Twin E. function has been activated for twin-engine 

aircraft, independent throttle curves are available for each 

engine to help eliminate any discrepancies in the throttle 

response between the two engines.

If the aircraft is equipped with an engine that has a nonlinear response, set up a throttle curve as described below.

1. Highlight and select THRO CURV in the FUNC.LIST. 

Two different throttle curves may be defined and they 

are named or otherwise referenced by Pos0 and Pos1.

2. If there is a need to have 2 throttle curves (i.e. a 

regular curve and a curve for torque rolling), use the 

Selector to highlight SW SELECT and a list of available 

Flight Modes and switches appears. Select the Flight 

Mode(s) (FM0, FM1, or FM2) and/or switch(es) that is 

to select between the 2 curves. The switch will be used 

to select between the Pos0 curve and the Pos1 curve. 

Highlight and select Pos0 to toggle between the Pos0 

and Pos1, in order to display and adjust the 2 curves.

[THRO CURV]◊0 Point-L

Point-1

Point-2

Point-3

Point-4

Point-5

Point-H

 0.0%

 INH

 INH

 50.0%

 INH

 INH

100.0%

Pos.0

SW SELECT

EXP

OFF

IN 5 OUT 5

THRO

STK INH

L 1 2 3 4 5 H

[THRO CURV] ◊0 Point-L

Point-1

Point-2

Point-3

Point-4

Point-5

Point-H

 0.0%

 INH

 INH

 50.0%

 INH

 INH

100.0%

Pos.0

SW SELECT

EXP

OFF

IN 5 OUT 5

THRO

STK INH

L 1 2 3 4 5 H

FMO FM1 FM2 AIL GER RUD MIX POS1

POS0
THRO CURV – THROTTLE CURVE (continued)

A-24

3. Scroll over to OFF under EXP and select it to turn 

exponential ON. This will result in a smoothed 

throttle curve.

4. Scroll over to Point-3 and select it. Set the Point-3 

value to 25%. This will yield a preliminary throttle 

curve that provides a good starting point for further 

adjustments. The remainder of the adjustments should 

be made with the engine running and the aircraft 

securely restrained so that it cannot possibly move.

Note: If Twin E. has been activated for a twin engine 

aircraft, there will be a Pos0 and Pos1 for both the 

right and left engines, providing a total of 4 possible 

throttle curves. 

5. Warm up the engine to its normal operating 

temperature. Move the throttle stick to full idle and 

slowly advance the throttle 1 click at a time. There 

should be a noticeable change in rpm for each 

movement of the stick. If while moving the stick it 

seems that the engine should be running faster or 

slower for a given throttle stick position, select the 

point that is closest to the vertical line (cursor) and 

increase the value if the engine is running too slow 

or decrease the value if the engine is running too fast 

for the stick position. Repeat as necessary until the 

desired response is obtained.

However, instead of being named Pos0 & Pos1, 

they are named RTH.0, RTH.1, LTH.0, and LTH.1. 

They represent Right Throttle Pos0 & Pos1 and Left 

Throttle Pos0 & Pos1 respectively.

[THRO CURV]◊0 Point-L

Point-1

Point-2

Point-3

Point-4

Point-5

Point-H

 0.0%

 INH

 INH

 50.0%

 INH

 INH

100.0%

RTH.0

SW SELECT

EXP

OFF

IN 5 OUT 5

THRO

STK INH

L 1 2 3 4 5 H

RTH.O

RTH.1

LTH.0

LTH.1

[THRO CURV]◊0 Point-L

Point-1

Point-2

Point-3

Point-4

Point-5

Point-H

 0.0%

 INH

 INH

 25.0%

 INH

 INH

100.0%

Pos.0

SW SELECT

EXP

OFF

IN 5 OUT 5

THRO

STK INH

L 1 2 3 4 5 H
FLAP SYS. – FLAP SYSTEM

A-25

The X9303 2.4 features a three-position Flap System 

with Elevator compensation, programmable Delay, and 

an Auto Land feature. Its purpose is to allow the flaps to 

be deployed in two different positions in addition to the 

normal or fully retracted position. The Flap System is 

available in the FUNC.LIST only if SYS. is selected on the 

OUT line under FLAP in the Devic. SEL function within the 

SYSTEM Menu. 

Because deploying flaps generally causes a change in 

pitch (Elevator trim), the Flap System provides for setting 

an Elevator deflection for each flap position. This is called 

Elevator Compensation. There is also a programmable Delay 

in .1 second increments up to a maximum of 2 seconds. 

The Delay determines how long it takes for the Flaps and 

Elevator to reach their positions. The X9303 2.4 ensures that 

the Flaps and Elevator reach their positions at the same time 

resulting in smooth Flap deployment and retraction. 
AUTO LAND (Flap System)

A-26

1. If Auto Land is to be used, scroll to INH under AUTO 

LAND and select it with the Selector. INH will 

change to ACT when selected and toggles between 

ACT and INH each time the Selector is pressed.

The Auto Land feature, if implemented, automatically 

retracts the Flaps and Elevator compensation when the 

throttle is raised above a specified throttle position. This 

can be useful during a missed landing approach when a 

go-around is required. The Flap System allows the Flaps 

to be deployed using the Flap Switch, Flight Mode switch 

or a combination of both. 

2. Scroll down to THRO and press the Selector to 

show the throttle percentage. Rotate the selector 

until the throttle percentage (0–100%) is equal to 

where the Auto Land feature is to retract the Flaps

and Elevator compensation. 

It is recommended that the throttle position be set very 

high at first (between 90–99%) to give the aircraft a 

chance to regain some speed before the Flaps actually 

retract. As the Flaps retract, lift will decrease and the stall 

speed of the aircraft will increase and may cause a crash if 

the airspeed is too low. When there is a missed approach, 

advance the throttle slowly up to about 90% and wait until 

the aircraft picks up some speed before advancing the 

throttle to full, causing the Flaps to retract.

Highlight and select FLAP SYS. in the FUNC.LIST to 

obtain the Flap System display if the aircraft has flaps or 

Flaperons that are also going to be used as flaps.

[FLAP SYS.]◊N

FLAP SW

AUTO LAND

INH

NORM

ELEV Mid

Land

NORM

FLAP Mid

Land

0%

0%

0%

U100%

0%

D100%

FM0: SW

FM1: SW

FM2: SW

Delay

 INH

[FLAP SYS.]◊N

FLAP SW

AUTO LAND

 ACT

THRO 95

NORM

ELEV Mid

Land

NORM

FLAP Mid

Land

0%

0%

0%

U100%

0%

D100%

FM0: SW

FM1: SW

FM2: SW

Delay

 INH
ELEV – ELEVATOR COMPENSATION (Flap System)

A-27

The ELEV values represent the Elevator deflection that 

will occur when the Flaps are deployed to their various 

positions. Some trial and error will probably be required 

to arrive at the right values, but once set, the aircraft will 

assume the proper pitch attitude for all flap positions.

1. Make sure the NORM value next to ELEV is set to 

0% as there should be no Elevator deflection with

the flaps in their fully retracted (up) position. If it 

is not 0%, scroll to NORM next to ELEV, select it, 

and then set the value to 0%.

2. Scroll to the Mid parameter beside ELEV and select it. 

Set the value either U (up) or D (down) to introduce up 

or down Elevator trim for the Mid position of the flaps. 

If not sure about which direction, aircraft typically pitch 

up when flaps are deployed, requiring some Down 

Elevator input to compensate. Use a small percentage 

like 3–5% at first and, after test flying, adjust the value 

a little at a time until the aircraft maintains the correct 

pitch attitude (typically slightly nose down) when the 

flaps are deployed to the Mid position.

3. Scroll to the Land parameter beside ELEV on the 

display and press the Selector to select it. Set the 

value either U (up) or D (down) to introduce a small 

amount (5–10%) of up or down Elevator for the Land 

position of the flaps, in the same fashion as setting up 

the Mid position above.

[FLAP SYS.]◊N

FLAP SW

AUTO LAND

 ACT

THRO 95

NORM

ELEV Mid

Land

NORM

FLAP Mid

Land

0%

 D105%

0%

U100%

0%

D100%

FM0: SW

FM1: SW

FM2: SW

Delay

 INH

[FLAP SYS.]◊N

FLAP SW

AUTO LAND

 ACT

THRO 95

NORM

ELEV Mid

Land

NORM

FLAP Mid

Land

0%

D105%

 D110%

U100%

0%

D100%

FM0: SW

FM1: SW

FM2: SW

Delay

 INH
FLAP – (Flap System)

A-28

The FLAP values represent how far the flaps deflect when 

in the NORM, Mid, and Land positions. The NORM 

position represents normal flying where the flaps are fully 

retracted. The Mid position is typically used for short 

field takeoffs and the Land position is typically used for 

landing. Refer to the aircraft manufacturer’s specifications 

for recommended flap deflections.

1. Put the Flap switch in its uppermost (Normal) position 

(no flaps deployed). Scroll to the NORM parameter 

next to FLAP on the display. It should be at U100%. If 

it is not, select it with the Selector and set it to 100% 

or the value that brings the flaps up to their normal 

flying position (no flaps deployed) with the Flap switch 

in the uppermost or Normal position.

2. Put the Flap switch in the Mid position. Scroll to the 

Mid parameter next to FLAP on the display and 

select it. Dial in a Down percentage to deflect the flaps 

downward the desired amount. The example above, 

shows a value of 25% but the aircraft manufacturer’s 

specifications should be used to set this value to 

achieve the recommended partial flap deflection.

3. Put the Flap switch in the lowermost or Land

position. Scroll to the Land parameter next to FLAP 

on the display and select it. Dial in a Down 

percentage to deflect the flaps downward the amount 

required for landing. The illustration below shows 

a value of 80% but the aircraft manufacturer’s 

specifications should be used to set this value to 

achieve the recommended deflection.

[FLAP SYS.]◊N

FLAP SW

AUTO LAND

 ACT

THRO 95

NORM

ELEV Mid

Land

NORM

FLAP Mid

Land

0%

D115%

D110%

U100%

D125%

D100%

FM0: SW

FM1: SW

FM2: SW

Delay

 INH

[FLAP SYS.]◊N

FLAP SW

AUTO LAND

 ACT

THRO 95

NORM

ELEV Mid

Land

NORM

FLAP Mid

Land

0%

D115%

D110%

U100%

D125%

D180%

FM0: SW

FM1: SW

FM2: SW

Delay

 INH
FM0-FM2 (Flap System)

A-29

If Flight Modes have been activated in the Devic. SEL

function of the SYSTEM Menu then FM0, FM1 and FM2 

will appear along the right side of the Flap System display 

to represent the 3 Flight Modes. Each of the Flight Modes 

can be assigned one of the Flap values (NORM, Mid, or 

Land), so when that Flight Mode is selected during flight, 

the Flaps deploy to that position. SW is also an option. 

When SW is selected for a Flight Mode, flap operation is 

controlled by the Flap switch when in that Flight Mode. 

If Flight Modes have not been activated, skip this portion 

of the Flap System.

1. For each Flight Mode, highlight and select FM0-FM2

and select either a flap position (NORM, Mid, Land) 

that the flaps are to assume when in that Flight Mode, 

or select SW if the Flap switch is to control the flaps 

when in that Flight Mode. 

The example above shows that Flight Mode 0 (FM0) is 

set to SW which means that the Flap switch will be used 

to control flaps when in this Flight Mode. FM1 is set to 

Mid, resulting in the flaps deflecting to the Mid position 

when Flight Mode 1 is selected and FM2 is set to Land, 

indicating that the flaps will deploy to the Land position 

when Flight Mode 2 is selected.

[FLAP SYS.]◊N

FLAP SW

AUTO LAND

 ACT

THRO 95

NORM

ELEV Mid

Land

NORM

FLAP Mid

Land

0%

D115%

D110%

U100%

D180%

D100%

FM0: SW

FM1: Mid

FM2:Land

Delay

 INH
Delay (Flap System)

A-30

The Delay parameter determines how long it takes for 

the flaps and Elevator to reach their positions. The 

X9303 2.4 automatically times the Flaps and Elevator so 

that they reach their positions at the same time, resulting 

in very smooth Flap deployment and retraction. The Delay 

is adjustable in .1 second increments up to a maximum

of 2 seconds.

1. Highlight and select Delay in the Flap System

display using the Selector. Then use the rotary to 

select a delay between .1 second and 2.0 seconds.

[FLAP SYS.]◊N

FLAP SW

AUTO LAND

 ACT

THRO 95

NORM

ELEV Mid

Land

NORM

FLAP Mid

Land

0%

D115%

D110%

U100%

D180%

D100%

FM0: SW

FM1: Mid

FM2:Land

Delay

 2.0s
ELEFLP M – ELEVATOR-TO-FLAP MIXING

A-31

The X9303 2.4 features a built-in mixer for Elevator-toFlap. The mixer causes the Flaps (or Flaperons) to move 

when the Elevator is moved, resulting in tighter looping 

maneuvers, or to provide some Aileron reflex for some 3D 

maneuvers such as Harriers. Typically, the flaps are set 

to travel downward with up Elevator and to travel upward 

with down Elevator with the exception of adding reflex for 

3D maneuvers such as harriers, in which case the reverse 

is set up so that the flaps travel up with up elevator and 

down with down elevator. The direction that the flaps 

travel with Elevator input can be changed by using 

positive and negative values.

If Elevator-to-Flap mixing is desired for the aircraft, 

perform the steps below.

1. Highlight and select ELEFLP M in the FUNC.LIST

to obtain the Elevator-to-Flap mix display.

2. There are 2 sets of mixing values available – Pos0 or 

Pos1. If the Pos0 values are left at 0% then the mixer 

may be turned on and off – Pos0 will be OFF and Pos1 

will be ON (this can be reversed by leaving the Pos1 

values at zero and putting values in Pos0). Highlight 

and select DN next to Pos1 and set the value to give 

the desired amount of Flap travel in the Down direction 

when full Up Elevator is applied.

3. Highlight and select UP next to Pos1 and set the value 

to give the desired amount of Flap travel in the UP 

direction when full Down Elevator is applied.

4. Scroll down to the bottom line of the display to select 

the Flight Mode(s) and/or switch(es) that is to be used 

to turn the mixer on and off. The throttle may also 

be used to turn the mixer on and off by highlighting 

and selecting THRO STK and setting the percentage 

of throttle to the point where the mixer is to switch 

between on and off.

Note: Pos1 always has priority over Pos0. In other 

words, if multiple switches are selected to turn the 

mixer on and off and one of the switches is in its 

Pos1 position, then all other switches are ignored 

and the Pos1 values are in effect.

[ELE≥FLP M]◊0-U

Pos0: DN 0% Pos1: DN 0%

Pos0: UP 0% Pos0: UP 0%

THRO

STK

 INH

FM0 FM1 FM2 AIL GER RUD MIX POS1

POS0

[ELE≥FLP M]◊0-U

Pos0: DN 0% Pos1: DN+ 30%

Pos0: UP 0% Pos0: UP+ 30%

THRO

STK

 INH

FM0 FM1 FM2 AIL GER RUD MIX POS1

POS0
AILRUD M – AILERON-TO-RUDDER MIXING 

A-32

The X9303 2.4 features a built-in mixer for Aileron-toRudder. The mixer causes the Rudder to deflect when 

the Ailerons are moved resulting in coordinated turns. 

This is a useful function for high-wing aircraft with flatbottomed airfoils because the Ailerons are typically not 

very effective, and Rudder input combined with Aileron 

input dramatically improves the turn and bank authority 

for these aircraft. The Rudder normally moves in the 

same direction as the Ailerons, however, the Rudder can 

be made to move in either direction by using positive or 

negative values.

If the aircraft requires Aileron-to-Rudder mixing, perform 

the steps below.

1. Highlight and select AILRUD M in the FUNC.LIST

to obtain the Aileron-to-Rudder mix display.

2. There are 2 sets of mixing values available – Pos0 and 

Pos1. If the Pos0 values are left at 0% then the mixer 

may be turned on and off – Pos0 would be off and 

Pos1 would be on (this can be reversed by leaving 

the Pos1 values at zero and putting values into Pos0). 

Highlight and select L next to Pos1 and set the value 

to give the desired amount of Left Rudder. A negative 

value will reverse the direction.

3. Highlight and select R next to Pos1 and set the value 

to give the desired amount of Right Rudder. A negative 

value will reverse the direction.

4. Scroll down to the bottom line of the display to select 

the Flight Mode and/or switch(es) that is to be used to 

turn the mixer on and off. The example below shows 

Flight Mode 2 set to Pos1, turning on the Aileron-toRudder mix. The throttle may also be used to turn the 

mixer on and off by highlighting and selecting THRO 

STK and setting the percentage of throttle to the point 

where the mixer is switched on/off.

Note: The Pos0 values can also be set to something 

other than zero causing a different amount of Rudder 

deflection to occur when there is Aileron input. One 

or more switches can then be selected to switch 

between the two sets of values. With this setup there 

will always be some mixing, as indicated by either 

Pos0 or Pos1, and the mixing cannot be turned off.

Note: Pos1 always has priority over Pos0. In other 

words, if multiple switches are selected to turn the 

mixer on and off and one of the switches is in its 

Pos1 position, then all other switches are ignored 

and the Pos1 values are in effect.

[AIL≥RUD M]◊0-L

Pos0: L 0% Pos1: L 0%

Pos0: R 0% Pos0: R 0%

THRO

STK

 INH

FM0 FM1 FM2 AIL GER RUD MIX POS1

POS0

[AIL≥RUD M]◊0-L

Pos0: L 0% Pos1: L + 50%

Pos0: R 0% Pos0: R + 50%

THRO

STK

 INH

FM0 FM1 FM2 AIL GER RUD MIX POS1

POS0
AIL DIFF. – AILERON DIFFERENTIAL

A-33

When Ailerons are deflected, the Aileron that deflects 

downward typically creates more drag than the Aileron 

that deflects upward. If the difference in drag is great 

enough, it will cause the aircraft to yaw in the direction 

of the down Aileron, i.e. a roll to the right will cause the 

aircraft to yaw to the left because the left Aileron deflects 

downward and creates more drag. This, of course, is an 

undesirable tendency that results in non-axial rolls and a 

loss of heading.

The X9303 2.4 provides an Aileron Differential function 

that allows adjustment of the Aileron that deflects 

downward without affecting the Aileron that travels upward 

and, therefore, can eliminate yaw tendencies in rolling 

maneuvers. It can also affect only the Aileron that travels 

upward—this is called negative differential and is useful if 

an aircraft yaws in the same direction as the Aileron input.

Aileron differential is available in the FUNC.LIST only if 

the FLAPERON Wing Type was selected in the Wing Type 

function in the SYSTEM Menu or a Dual channel has been 

assigned to ailerons in the Wing TYPE function.

The Aileron Differential function provides for 2 differential 

settings that are switch or Flight Mode selectable – Pos0 

and Pos1. The 2 settings can be combined in different 

ways to provide one setting that is on all of the time, or 

one setting that is on and one that is off (0 differential), or 

2 different amounts of differential—maybe one for normal 

flying and another for flat spins.

To use the Aileron Differential function, highlight and 

select AIL Diff. in the FUNC.LIST to obtain the Aileron 

Differential display.

1. If there is to be a single Aileron differential setting that 

is on all of the time, highlight and select Pos0 and 

set a small percentage of differential. A positive value 

causes the downward Aileron to travel less while a 

negative value causes the upward Aileron to travel 

less (negative differential). Test fly the aircraft and 

return to this function to make adjustments until the 

yaw tendency has been eliminated. That is all that is 

required to set up a single differential setting that is 

always on.

[AIL Diff.]◊0

Pos0: + 5% Pos1: LIN

THRO

STK

 INH

FM0 FM1 FM2 AIL GER RUD MIX POS1

POS0
AIL DIFF. – AILERON DIFFERENTIAL (continued)

A-34

2. If there are to be 2 Aileron differential values you can 

select a switch to control the differential amount and 

set each position as desired. If one of these values is 

set to zero, Aileron differential can be turned off by 

selecting the position that has the 0 values. Highlight 

and select Pos0 and set a small percentage of 

differential or leave it set to zero (0) if the ability to turn 

differential off is desired. Highlight and select Pos1 

and set the percentage of differential. A positive value 

causes the downward Aileron to travel less, while a 

negative value causes the upward Aileron to travel less 

(negative differential). The example below shows a 

positive percentage in Pos0 for precision flying and 

a negative differential for Pos1 for flat spins, which is 

selectable with Flight Mode 2 (FM2).

3. Scroll down to the bottom line of the display to select 

the Flight Mode and/or switch(es) that is to be used 

to switch between the Aileron Differential settings. The 

throttle may also be used to switch between differential 

settings by highlighting and selecting THRO STK and 

setting the percentage of throttle to the point where 

the values are switched. Test fly the aircraft and return 

to this function to make adjustments until the yaw 

tendency has been eliminated.

Note: Pos1 always has priority over Pos0. In

other words, if multiple switches are selected and 

one of the switches is in its Pos1 position, then

all other switches are ignored and the Pos1 values 

are in effect.

[AIL Diff.]◊0

Pos0: + 5% Pos1: - 25%

THRO

STK

 INH

FM0 FM1 FM2 AIL GER RUD MIX POS1

POS0
SRV. SPEED – SERVO SPEED

A-35

The X9303 2.4 system provides the ability to adjust the 

speed of servos on each channel in both directions. The 

speed may be adjusted downward (servo slowed) from its 

normal speed but it cannot cause a servo to move faster 

than its rated specifications. Furthermore, each servo can 

have 2 sets of speeds in both directions that are Flight 

Mode or switch selectable.

The servo speed function is very useful for scale models 

with retractable landing gear and gear doors, since in 

many instances the need for gear door sequencers can be 

eliminated. If the gear door servos move at normal speed 

and the landing gear servos move at a slower speed when 

the gear is lowered, the gear doors will be open before 

the landing gear begins to come down. In the opposite 

direction, if the gear door servos move slowly and the 

landing gear servos move at normal speed, the gear can 

retract before the gear doors begin to close. 

Note: Most mechanical retract servos are nonproportional type servos that simply move from end 

point to end point. These types of servos are not 

adjustable in the servo speed function.

Servo speed can also be useful on the throttle channel. 

The throttle servo can be slowed down such that the 

engine will not flameout because the carburetor is opened 

or closed too quickly when the throttle stick is jammed 

from low to high and vise versa.

To adjust servo speed, highlight and select SRV. Speed

in the FUNC.LIST. 

1. If there is to be a single set of servo speeds that are in 

effect all of the time, make sure the display is showing 

Pos0. If it is not, select Pos1 and change it to Pos0.

Highlight and select the channel and direction for each 

servo that is to be adjusted. Once a direction for a servo is 

selected, the servo speed may be set so the servo travels 

from .176 seconds for 60 degrees of rotation all the way 

up to 15 seconds for 60 degrees of rotation. Adjust the 

speed of each servo until the desired speed is obtained. 

The example below shows the throttle servo slowed down 

so that it traverses 60 degrees in 1.25 seconds in both 

directions. That is all that is required when there is only 1 

set of servos speeds.

2. If there are to be 2 sets of servo speeds that are Flight 

Mode or switch selectable you can select a switch 

to control the servo speed and set each position as 

desired.. If one set of values is set to NORM for 

all channels, slowing of servos can be turned off 

by selecting the position (Pos0 or Pos1) that has 

the NORM values. Highlight and select Pos0 and 

change it to Pos1 and then highlight and select the 

channel and direction for each servo that is to be 

adjusted. Once a direction for a servo is selected, the 

servo speed may be set so the servo travels from .176 

seconds for 60 degrees of rotation all the way up to 15 

seconds for 60 degrees of rotation. Adjust the speed 

of each servo until the desired speed is obtained. 

Highlight and select Pos0 and then highlight and 

select the channel and direction for each servo that is 

to be adjusted. Switch between Pos0 and Pos1 to 

view and adjust the 2 sets of values for each servo.

3. Scroll over to and select SW SELECT to identify 

the Flight Mode and/or switch(es) that is to be used 

to switch between the 2 sets of servo speeds. The 

throttle may also be used to switch between differential 

settings by highlighting and selecting THRO STK and 

setting the percentage of throttle to the point where the 

values are switched. 

Note: Pos1 always has priority over Pos0. In

other words, if multiple switches are selected and 

one of the switches is in its Pos1 position, then

all other switches are ignored and the Pos1 values 

are in effect.

[SRV.Speed]◊0

THRO

STK INH

THRO

AILE

ELEV

RUDD

1.25

NORM

NORM

NORM

1.25

NORM

NORM

NORM

NORM

NORM

NORM

NORM

NORM

NORM

NORM

NORM

NORM

NORM

GEAR

FLAP

AUX2

AUX3

[sec/60 ] AUX4

SW

SELECT

Pos0
SNAP ROLL

A-36

The X9303 2.4 has a Snap Roll system that is comprised of 

a Snap Roll switch that is used in conjunction with Flight 

Modes to select a direction (Right/Up, Right/Down, Left/

Up, and Left/Down) and deflections for Aileron, Elevator 

and Rudder. Up to four directions and corresponding rates 

can be programmed and a Direction/Rate combination can 

be assigned to 1 or more of the 3 Flight Modes. Pressing 

the Snap Roll switch causes the aircraft to snap roll in the 

direction and according to the rates assigned to the Flight 

Mode that is currently selected. 

If Flight Modes have been activated, 3 of the Snap Roll 

directions/rates can be assigned to them —one per Flight 

Mode. If Flight Modes have not been activated then only 

one of the directions/rates may be active and it must be 

set/selected in the Snap Roll function. The Snap Roll 

function is inhibited as a default and must be turned on in 

order to use it.

If the Snap Roll function is to be used, highlight and 

select Snap Roll in the FUNC.LIST and then select 

INH to activate it.

1. If Flight Modes were activated in the Devic. SEL

function, FM0, FM1, and FM2 will appear down 

the left hand side of the display. Select each one and 

assign a direction (RIGHT-DOWN, RIGHT-UP, 

LEFT-DOWN, LEFT-UP) from the list for each of the 

3 Flight Modes.

If Flight Modes are not activated, only a single direction 

appears along the left-hand side of the display. Highlight 

and select it and pick one of the directions.

2. Scroll over to the AILE deflection of the first direction 

(R-D) and set it to a rather high percentage. Scroll 

down to the ELEV deflection for the same direction 

and set it to a modest value of perhaps 40% to prevent 

“burying” the aircraft with too much Elevator during the 

snap. Now scroll down to the RUDD deflection and set 

it to a modest value like the Elevator.

3. Repeat step 2 for the other 3 directions.

[Snap Roll]

ACT

FM0:R-D

FM1:R-U

FM2:L-D

AILE100%

L-D ELEV 40%

RUDD 40%

AILE100%

L-U ELEV 40%

RUDD 40%

AILE100%

R-D ELEV 40%

RUDD 40%

AILE100%

R-U ELEV 40%

RUDD 40%
GYRO SYS. – GYRO SYSTEM

GYRO CONNECTIONS (Gyro System)

A-37

The X9303 2.4 features a very sophisticated Gyro Gain 

Sensitivity System that allows in-flight selection of 3 gyro 

gains for two separate gyros. It provides for fixed gain 

values as well as a Stick Override Gain, where gyro gain 

is progressively reduced as the stick is moved further 

off center. Stick Override Gain is an absolute “must” for 

controlling gyros in aerobatic aircraft.

Note: In order for the GYRO System to appear 

in the FUNC.LIST, the AUX2 and/or the AUX3 

channels must be set to GYRO on the OUT Line of 

the Devic.SEL display. If neither of these are set to 

GYRO, then GYRO System will not appear as a 

function in the FUNC.LIST.

Up to 2 gyros may be used to control two of the three 

primary flight controls (Elevator, Rudder, or Aileron). 

Typical applications involve gyros on the Rudder 

and/or Elevator. The FLAP and/or AUX2 switch can be 

used to switch between the 3 different gains for each 

gyro. The gyro gains can also be controlled by Flight 

Modes. The gains can be fixed or variable using the 

Stick Override Gain feature. If one set of gains for each 

gyro is set to zero, then the gain/gyro can essentially be 

switched off during flight.

Note: This function is designed to be used only 

with gyros that have in-flight proportional gain 

adjustment capability. Single and dual rate gyros that 

use a potentiometer to adjust the gain will not work 

properly with this function.

Plug the gain connector of one gyro into the AUX2 port 

of the receiver. Plug the gain connector of another gyro (if 

any) into the AUX3 of the receiver. If only one gyro is to 

be used, connect its gain to either AUX2 or AUX3. 

Note: The OUT line at the bottom of the Devic.

SEL function must be set to GYRO for AUX2 and/

or AUX3 if they are to be used to control Gyros.
FIXED GYRO GAIN (Gyro System)

A-38

Fixed Gyro Gain does not use the Stick Override Gain 

feature. Whichever of the 3 gains is presently selected 

remains in effect and moving the control stick does not 

affect the gain. 

1. To access the GYRO System, highlight and select 

GYRO SYS. in the FUNC.LIST.

AUX2 gain settings appear in the top half of the display 

while the AUX3 settings appear in the lower half of 

the display. They will appear only if AUX2 and/or

AUX3 have been set to GYRO on the OUT line of the 

Devic.SEL function.

2. Decide on which switch to use to control gyro gain. 

The Flap switch and the AUX2 switch are the only 3-

position switches that can be used by the Gyro System. 

One switch can be used to select the gain for both 

gyros, or each gyro can use a different switch to select 

the gain. Typically, one switch is used to control the 

gain, even when 2 gyros are used. 

Highlight and select AX2 SW or FLP SW next to AUX2 

and AUX3 until the desired switch is displayed next to 

each. The example below shows the AUX2 switch 

selected for both gyros.

3. Each gyro has 3 possible gain settings. They are 

labeled 0, 1, and 2 next to CEN on the display, 

with a percentage next to each (CEN stands for gyro 

gain when the control stick is at center – no stick 

deflection). They correspond to the positions of a 

3-position switch where 0 represents the switch being 

in the upper position; 1 represents the middle position; 

and 2 represents the lower position. It is recommended 

that the 0 position (upper switch position) for each 

gyro be set to zero (0%) which allows the gyro to 

be turned off in flight (very useful if a gyro suddenly 

becomes overly sensitive).

4. Use the Selector to highlight and select the number 0 

position for each gyro and set the percentage to 0% if 

not already at a 0% value.

5. Select the number 1 gain for each gyro and set it to 

some moderate value. The example shows 50% gain 

set for both gyros.

6. Select the number 2 gain for each gyro and set it to a 

relatively high value. The example shows 85% gain set 

for both gyros.

7. If Flight Modes have not been activated, skip to the 

next step. 

If Flight Modes have been activated in the Devic. SEL

function, a list of Flight Modes (FM0, FM1, FM2) is 

displayed to the right of the display for each active Gyro. 

The default setting for each Flight Mode is S, indicating 

that the 3-position gyro switch will control the gyro gain 

when in that Flight Mode. The S can be changed to 

0, 1, or 2 to represent the gain values associated with the 

positions of the 3-position switch. For example, if FM1 is 

set to 0, then when in Flight Mode 1, the gain will be 0% 

which corresponds to the gain of the upper position of 

the 3-position switch. If FM1 is set to 1, the gain will be 

50%, and if FM1 is set to 2, the gain will be 85% when in 

Flight Mode 1.

Highlight and select each FM parameter and set it to S, 0, 

1, or 2 to indicate if the Gyro switch will control gyro gain 

while in that Flight Mode, or to assign one of the gains 

to the flight Mode. The example above shows all Flight 

Modes as deferring gyro gain control to the 3-position 

gyro gain switch – in this case the AUX2 switch.

8. This completes the Fixed Gyro Gain setup. In the 

example, the AUX2 switch is being used to select 

the gain of both gyros at the same time. The upper 

position of the switch selects 0%, essentially turning 

the gyros off. The middle position selects 50% for both 

gyros and the lower position selects 85% gain for both 

gyros. The selected gain does not change when the 

sticks are moved.

[GYRO SYS.]

AUX2: AX2 SW

 STICK INH

AUX3: AX2 SW

 STICK INH

0: 00%

1: 50%

2: 85%

CEN

◊0

FM0: S

FM1: S

FM2: S

FM0: S

FM1: S

FM2: S

CEN0: 00%

1: 50%

2: 85% ◊0
STICK OVERRIDE GYRO GAIN (Gyro System)

A-39

Stick Override Gyro Gain is very popular with aerobatic 

pilots, as it allows the pilot to instantaneously override 

the gyro by moving the stick. Gyro gain decreases as 

the stick is moved further from neutral and is typically 

set up so that gyro gain is reduced to zero when the 

stick is at full deflection. When the stick is released and 

allowed to center, gyro gain is instantaneously restored. 

In other words, the pilot assumes control of the channel 

by moving the stick and returns control of the channel to 

the gyro by releasing the stick. This helps in performing 

excellent hammerheads/stall turns, as the gyro is 

overridden by the Rudder stick in performing the pivot, 

but instantly dampens out any “wiggle” as soon as the 

pivot is completed and the Rudder stick is released.

Stick Override Gyro Gain is identical to Fixed Gyro Gain 

in all regards except that the control stick(s) progressively 

reduces the presently selected gyro gain as the stick(s) is 

moved off of center. As mentioned before, it is typically 

set up so that when the stick reaches full deflection, the 

gyro gain is reduced to zero.

1. To access the Stick Override Gyro Gain feature, 

highlight and select GYRO SYS. in the FUNC.LIST.

2. Perform all of the steps outlined for 

Fixed Gyro Gain above.

3. Scroll over to and select STICK for each gyro and 

select the stick that corresponds with the control 

surface being controlled by the gyro. For example, 

if AUX2 is controlling the gain for the Rudder gyro, 

select RUDD as the stick for AUX2. If AUX3 is 

controlling the gyro for Elevator, select ELEV as the 

stick for AUX3.

4. Once a stick has been selected, a new set of END 

percentages appears on the display— all with a value 

of 50%. These new percentages indicate the gyro gain 

when the stick is moved to full deflection. If set to 0%, 

the gain will be progressively reduced as the stick is 

moved off center until it reaches 0% when the stick is 

at full deflection.

It is recommended that all END percentages be set to 

0% unless there is a specific need to do otherwise. The 

default value of all END percentages is 50%. Use the 

Selector to highlight and select each END percentage 

and set each one to 0%.

[GYRO SYS.]

AUX2: AX2 SW

 STICK RUDD

AUX3: AX2 SW

 STICK ELEV

0: 00%

1: 50%

2: 85%

CEN

◊0

FM0: S

FM1: S

FM2: S

FM0: S

FM1: S

FM2: S

CEN0: 00%

1: 50%

2: 85%

END0: 0%

1: 0%

2: 0%

END0: 0%

1: 0%

2: 0%

◊0
PROG MIX – PROGRAMMABLE MIXERS

A-40

The X9303 2.4 System provides 4 Standard 

programmable mixers (PROG.MIX3 - PROG.MIX6) and 2 

Multi-Point programmable mixers (PROG.MIX1 & PROG.

MIX2). Programmable mixers are used whenever the pilot 

wants a channel to react or move as a result of providing 

input to another channel, or to simply cause a channel to 

move by moving a switch or lever. They are typically used 

to compensate for deficiencies in aircraft design/setup, 

such as eliminating pitch- and roll-coupling in knife-edge 

flight, and to activate special aircraft functions like smoke 

systems, speed brakes, bomb drops, idle-up, etc.

Multi-Point Mixing provides the ability to define a 

customized “curve” of travel that the Slave channel will 

follow as it reacts to the Master channel. It is different 

from Normal Mixing in the sense that Normal Mixing 

results in a linear movement of the Slave channel in 

relation to the Master. With Multi-Point Mixing there are 

7 points (including end points) along the travel of the 

Master channel that can be adjusted to control the action 

of the Slave channel (more or less travel in the same/

opposite direction) providing the ability to deviate from a 

linear mixing action.

The channel that receives the original input from the pilot 

is called the Master channel, while the channel that reacts 

to the Master is called the Slave channel. Mixing occurs 

when the pilot provides an input to the Master channel 

by moving a stick, switch, or lever. The transmitter 

automatically generates an input for the Slave channel 

based on the pilot’s input to the Master channel and the 

parameters defined in the programmable mixer.

Mixes are programmable, allowing any of the 9 channels 

to be Master, Slave or both. Additionally there are 4 

options for Master channels that begin with a “#” (pound 

sign), these Master channels are origin type mixes. These 

include #THR, #AIL, #ELE, and #RUD. Origin mixing 

bypasses any other mixing that might affect that channel 

such as throttle curves or other programming and uses 

the stick position only to control the mix. Also the Master 

channel can be assigned to one of the two digital rocker 

switches, levers, or button. If dual functions have been 

activated in the device select function, it is possible for 

the Slave channel to be assigned to channels such as 

AILV, FPRN, FROL, and RUDV, these functions allow 

the ailerons to be moved as flaps, flaps to be moved as 

ailerons, elevators to be moved as ailerons, rudders to 

be moved as speed brakes either both in or both out, or 

similar functions.

Some examples of how programmable mixers might be 

used include but are certainly not limited to:

• Eliminate Roll-Coupling where the aircraft rolls 

when there is Rudder input. The mixer causes the 

Ailerons to move just a little bit in the opposite 

direction of the Rudder in order to keep the aircraft 

from rolling, while holding Rudder for knife-edge 

flight. This standard mixer would designate the 

Rudder as the Master and the Ailerons as the Slave. 

• Eliminate Pitch-Coupling where the aircraft 

pitches to the gear or canopy when holding Rudder 

for knife-edge flight. The mixer causes the Elevator 

to move a little when Rudder is applied to keep 

the aircraft from pitching while holding Rudder 

during knife-edge flight. This Multi-Point mixer 

would designate the Rudder as the Master and the 

Elevator as the slave. A Multi-Point mixer would 

be used because pitch-coupling is typically nonlinear in nature and requires a customized curve 

to counteract pitching that is induced by different 

amounts of Rudder deflection.

• Eliminate pulling out on down lines where 

the aircraft has a tendency to pull out towards the 

canopy when flying vertical down lines at idle. 

The mixer generates a bit of down Elevator when 

the throttle stick is pulled back to idle, making the 

aircraft track straight down with no input from the 

pilot. This mixer would designate the Throttle as 

the Master and the Elevator as the Slave and would 

be turned on and off with a switch so the down 

Elevator would not be generated during landing.

• Controlling a Smoke System where a switch 

is used to activate the smoke system and once 

activated, the smoke system comes on when the 

throttle stick is advanced beyond a certain point. 

This standard mixer would designate Throttle as 

the Master and an Auxiliary channel as a slave and 

would be turned on and off by a switch.

• Idle-Up where flipping a switch causes the engine 

rpm to increase a bit at idle to protect against 

a flameout during flying and then returning to 

low idle for landing. This standard mixer would 

designate an auxiliary channel as the Master and 

the Throttle channel as the Slave. It would also use 

a switch to turn the mixer on and off.

The possibilities are endless and limited only by the 

imagination.
STANDARD PROGRAMMABLE MIXER – Example: DOWN ELEVATOR AT IDLE

A-41

Perhaps the best way to describe a Programmable 

Mixer is by example. The example below demonstrates 

a program mix for an aircraft that pulls-out or pitches 

towards the canopy when trying to fly a vertical down line 

at idle. If a mix is set up to provide a couple of degrees of 

down Elevator when at idle, the aircraft will track straight 

down without input from the pilot. Once the throttle is 

advanced above idle, the mixer is turned off and the down 

Elevator is removed. The mixer can also be turned off so 

the down Elevator input does not occur during landing.

This mixer uses the Throttle as the Master and the 

Elevator as the Slave. The mix is turned on and off with 

the GEAR switch in combination with the position of the 

throttle stick – ON at idle and OFF above idle with the 

GEAR switch ON. When the GEAR switch is OFF, the mixer 

is turned off regardless of throttle setting. 

The Mix parameters will be selected and set in the 

following order: Program Mix number, Master, Slave, 

Switch, Travel/Direction, and Offset. This is generally a 

good sequence to follow when setting up Programmable 

Mixers.

1. Program Mix Number. Highlight and select one of 

the Standard Programmable Mixers (PROG.MIX3 - 

PROG.MIX6) to obtain the first Programmable Mix 

display. Then press ACT next to CLR or highlight 

and select INH to obtain the main mix display. The 

example is using PROG.MIX3.

2. Select Master. All Programmable Mixers default 

to Throttle as both the Master and the Slave 

(THROTHRO). The first THRO is the Master and 

the 2nd THRO represents the Slave.

Highlight and select the first THRO to the left of the 

arrow to obtain a list of channels that can be used as 

the Master. Highlight and select the #THR channel as 

the Master, bypassing any throttle curve settings. This 

will cause the physical position of the throttle stick to 

control the mixer.

3. Select Slave. Highlight and select THRO to the 

right of the arrow to obtain a list of channels that can 

be used as the Slave. Highlight and select ELEV as 

the Slave.

4. Select Switch. Scroll down, highlight, and select 

GER as the switch to be used to turn the mixer on and 

off. The GER indicator should now be in the upper or 

Pos1 position at the bottom of the display. Any of the 

switches along the bottom of the display can be used 

and multiple switches can be used if so desired. The 

example is using only the Gear switch.

5. Select Switch Position. Move the Gear switch back 

and forth while observing the number directly to the 

right of the Program Mix Name in the upper left hand 

corner of the display. The number will change from 0 

to 1 as the switch is moved back and forth. When the 

number is 0, the mixer is looking at the Pos0 values 

(not programmed yet) and when it is a 1, it is looking 

at the Pos1 values (also not programmed yet).

Put the switch in the position that is to turn the mixer 

ON. Look at the number directly to the right of the 

Program Mix Name. If it is 0, highlight and select 

Pos0 on the display. If it is 1, highlight and select 

Pos1 on the display. The example shows Pos0 as the 

position to turn the mixer ON.

6. Travel and Direction. With the switch still in the 

ON position, move the throttle stick to the full low 

position and the lower value next to the selected 

position should be highlighted. Set the lower position 

parameter to a low positive value like +3%. This is the 

amount of deflection of the Elevator (Slave channel) 

that is to occur when the mixer is turned on and the 

throttle is reduced to idle, or just enough to see a little 

down elevator deflection.

[PROG.Mix3]◊0

#THR≥ELEV

Offset -140

Pos0 0%

 3%

Pos1 0%

 0%

THRO

STK

 INH

FM0 FM1 FM2 AIL GER RUD MIX POS1

POS0

+
STD PROGRAMMABLE MIXER – Ex: DOWN ELEV AT IDLE (continued)

A-42

The Elevator should move slightly downward when the 

throttle is set to idle. If the Elevator moves upward, 

change the +3% to a –3% to reverse the direction that 

the Elevator travels. The Elevator can be made to move 

more by increasing the percentage (more negative 

or more positive) and move less by decreasing the 

percentage. After test flying the aircraft, adjust the 

percentage as may be necessary. Leave the upper value 

of the selected position at 0% because there is to be 

no Elevator input above idle.

7. Offset. Highlight and select OFFSET and set the 

value to -140 to -160. This represents a throttle stick 

position that is about 2–3 clicks up from full low 

stick. This is also the point where the mixer causes 

the Elevator to deflect the +3% set in the lower 

position value. Above this position there is no Elevator 

deflection and the Elevator returns to normal.

8. Verify Operation. Highlight and select the position 

containing the +3% value using the Selector, move 

the Gear switch to the ON position, and move the 

throttle stick upwards from idle while observing the 

position values. When the stick is brought down to 

idle, the lower Pos0 value is highlighted indicating the 

down Elevator deflection (+3%). Verify that the Elevator 

is deflecting downward slightly. When the stick is 

advanced above idle, the upper value is highlighted 

(0%) and the Elevator returns to normal (no mixing).

Now turn the Gear switch to the OFF position and 

note the number next to the Program Mix Name 

is now changed, indicating that the mixer is looking 

at the values in the other position. Since both of the 

values in this position are at 0% there is no deflection 

of the Elevator – the mixer is turned OFF regardless of 

throttle stick position. Verify that the Elevator does not 

move when the throttle stick is moved.

Note: To completely disable or otherwise 

inhibit a mixer, highlight either the Master or 

Slave and press the CLR button.
MULTI-POINT MIXER – Example: ELIMINATE PITCH-COUPLING

A-43

The example below demonstrates a Multi-Point Program 

Mix for aircraft that pitch towards the landing gear when 

holding Rudder for knife-edge flight – commonly known 

as Pitch-Coupling. If a mix is set up to provide an 

appropriate amount of up Elevator for different amounts of 

Rudder input, the aircraft will fly straight without pitching 

to the landing gear while holding Rudder during knifeedge flight. 

This Multi-Point mixer uses the Rudder as the Master and 

the Elevator as the Slave. The mix is turned on and off 

with the GEAR switch. 

The Mix parameters will be selected and set in the 

following order: Program Mix number, Master, Slave, 

Switch, Set Points Travel/Direction, and Offset. This is 

generally a good sequence to follow when setting up 

Multi-Point Programmable Mixers.

1. Program Mix Number. Highlight and select one 

of the Multi-Point Programmable Mixers (PROG.

MIX1 or PROG.MIX2) to obtain the first Multi-Point 

Programmable Mix display. Then press ACT next to 

CLR or highlight and select INH to obtain the main 

mix display. The example is using PROG.MIX1.

2. Select Master. All Programmable Mixers default 

to Throttle as both the Master and the Slave 

(THROTHRO). The first THRO is the Master and 

the 2nd THRO represents the Slave. 

Highlight and select the first THRO to the left of the 

arrow to obtain a list of channels and select RUDD

as the Master.

3. Select Slave. Highlight and select THRO to the 

right of the arrow to obtain a list of channels that 

can be used as the Slave. Highlight and select ELEV 

as the Slave.

4. Select Switch. Scroll over to and select SW 

SELECT to obtain a list of switches and then highlight 

and select GER as the switch to be used to turn the 

mixer on and off. The GER indicator should now be in 

the upper or ON position at the bottom of the display. 

Any of the switches can be used and multiple switches 

can be used if so desired. The example is using only 

the Gear switch.

[PROG.Mix1] Point-0

Point-1

Point-2

Point-3

Point-4

Point-5

Point-6

- 10

-INH

- 3

-IN0

- 3

-INH

- 10

RUDD≥ELEV

SW SELECT

EXP

ON

IN 50 OUT 0

THRO

STK INH

0 1 2 3 4 5 6

[PROG.Mix1] Point-0

Point-1

Point-2

Point-3

Point-4

Point-5

Point-6

- 10

-INH

- 3

-IN0

- 3

-INH

- 10

RUDD≥ELEV

SW SELECT

EXP

ON

IN 50 OUT 0

THRO

STK INH

0 1 2 3 4 5 6

ON FM0 FM1 FM2 AIL GER RUD MIX ON

OFF
MULTI-POINT MIXER – Ex: ELIMINATE PITCH-COUPLING (continued)

A-44

5. Set Points for Travel and Direction. There are 7 

points along the travel of the Rudder (the line that is 

intersected by the vertical line that moves right and 

left with the Rudder stick). At each point an Elevator 

deflection may be defined. A point that is set to 0% 

represents no Elevator deflection at that point. A 

negative value at a point typically indicates Up Elevator 

movement while a positive value results in Down 

Elevator movement. A point set to INH takes on the 

value of the curve/line between the 2 adjacent points. 

The direction of travel may be reversed (Up Elevator vs. 

Down Elevator) by changing values from negative (-) to 

positive (+) (moving the point values above and below 

the 0% line).

Since the aircraft pitches to the landing gear with the 

application of both Right and Left Rudder, the Elevator 

deflection will be zero at the center (Point-3) (no mixing) 

and the points either side of Point-3 will be negative, 

indicating Up Elevator movement. The more negative 

a point value, the more Up Elevator deflection. Set the 

points initially to the following values.

Point-0

 -10% (At full Right Rudder the Elevator will deflect 

Up 10%)

Point-1

INH (Takes on the value along the curve between 

Point-0 & Point-2)

Point-2

-3% (Elevator deflects Up 3% when Rudder is 

moved to Point-2)

Point-3

0% (no Mixing – no Elevator deflection when 

Rudder is at neutral)

Point-4

-3% (Elevator deflects Up 3% when Rudder is 

moved to Point-4)

Point-5 

INH (Takes on the value along the curve between 

Point-4 & Point-6)

Point-6

-10% (At full Left Rudder the Elevator will deflect 

Up 10%)

6. Offset. Point-3 represents the offset position and 

corresponds to the Rudder stick being at neutral. It is 

important to leave Point-3 set at 0% to make sure there 

is no mixing and therefore no Elevator deflection when 

the Rudder is at neutral.

7. Verify Operation. Turn the RX on and turn the mix 

on using the Gear switch. Move the Rudder stick 

from full right to full left. The Elevator should deflect 

Up when the Rudder is moved in both directions. If 

it moves down instead, change the percentages to 

(+) values instead of (-) values at each point. If the 

Elevator appears to be moving too much, reduce the 

point values (less negative). If the Elevator does not 

seem to move enough, then increase the point values 

(more negative). Now turn the Gear switch to the OFF 

position and verify that the Elevator does not move.

While test flying the aircraft, make note of the mixing and 

whether it is generating enough up-Elevator during knifeedge to stop it from pitching to the gear, or generating 

too much Elevator input, causing it to pitch to the canopy 

instead of the gear. Also note the approximate position of 

the Rudder stick when pitching occurs. Land the aircraft 

and adjust the points closest to the position of the Rudder 

stick when pitching occurs for more or less Elevator 

deflection until the aircraft no longer pitches during knifeedge. More negative generates more Up Elevator and less 

negative generates less Up Elevator. Points 1 and 5 may 

be activated and their value changed if necessary to finetune the mix.

Note: To completely disable or otherwise 

inhibit a mixer, highlight either the Master or 

Slave and press the CLR button.

[PROG.Mix1] Point-0

Point-1

Point-2

Point-3

Point-4

Point-5

Point-6

- 10

-INH

- 3

-IN0

- 3

-INH

- 10

RUDD≥ELEV

SW SELECT

EXP

ON

IN 50 OUT 0

THRO

STK INH

0 1 2 3 4 5 6
TRAINER – TRAINER SYSTEM

XP9303 USED AS MASTER (INSTRUCTOR) – (Trainer System)

A-45

The X9303 2.4 contains a Trainer System that allows the 

instructor to transfer some or all of the primary flight 

control functions (Throttle, Aileron, Elevator and Rudder) 

to the student. It also allows for indicating if the transmitter 

is to be the Master (controlled by the instructor) or Slave 

(controlled by the student). The Snap Roll button is used 

to transfer control to the student when the X9303 2.4 is 

being used as the Master/Instructor transmitter.

All Dual rates and Exponential settings in the Master 

transmitter are transferred to the Slave transmitter. The 

Slave transmitter battery must be charged.

1. Connect the Trainer cord between the Master and 

Slave transmitters. Turn the power on to the Master 

transmitter (the Slave transmitter remains powered off 

and can even have the module removed).

2. Make sure the Slave transmitter is in the PPM/FM 

modulation mode. If the slave system is a X9303 2.4, 

or any other system that is Spread Spectrum only, 

such as other JR 2.4GHz systems or Spektrum brand 

systems, this does not apply.

3. Highlight and select Trainer in the FUNC.LIST to 

obtain the Trainer Display.

1. If the X9303 2.4 is being used as the Master 

transmitter (the transmitter operated by the instructor), 

select the channel(s) that are to be operated by the Slave 

transmitter (transmitter operated by the student) when 

the trainer switch is depressed.

When all channel selectors are in the MAST position, 

NORMAL appears on the display and all 4 channels 

are transferred to the student when the trainer switch is 

depressed.

If only certain channels are to be transferred to the 

student, highlight and select the channels that are to be 

transferred, moving the indicator for these channels to 

the SLAV position for these channels. When less than all 

channels are selected as SLAV, PROGRAM T appears 

on the display indicating that the Trainer System has been 

programmed to transfer only selected channels.

The X9303 2.4 is now ready to be used as the Master 

or instructor transmitter. Depress the Snap Roll button 

to transfer control to the student. Control will remain 

transferred until the Snap Roll button is released.

[Trainer]

MASTER NORMAL T.

ch THRO AILE ELEV RUDD

SLAV

MAST
X9303 2.4 USED AS SLAVE (STUDENT) – (Trainer System)

A-46

Highlight and select MASTER and the display will 

switch to SLAVE. A message will appear instructing to 

Connect DSC & POWER off. Make sure the transmitter 

power switch is in the Off position and the DSC cord is 

connected between the 2 transmitters.

The X9303 2.4 is now ready to be used as the Slave or 

student transmitter.

[Trainer]

SLAVE Connect DSC & POWER off
TIMER – TIMER SYSTEM

A-47

The X9303 2.4 contains a Timer System that contains 

two timers. One is an integrated timer that keeps track of 

total time that the transmitter has been on for the model 

and it is displayed on the Main display. The other timer 

can be configured as either a Countdown timer or as a 

Stopwatch. This timer also appears on the Main display 

when active and can be started, stopped and reset from 

the Main display. It is a good idea to use the Countdown 

timer as a reminder that it is time to land so as not to run 

out of fuel.

1. To configure the timer as a Countdown timer highlight 

and select Timer in the FUNC.LIST to obtain the 

Timer display.

Highlight and select INH under TIMER and then select 

DOWN-T. Use the Selector to set the countdown start 

time. Once the timer is set, TIM will appear on the Main 

display in the lower left corner. Pressing the button next to 

TIM on the Main display starts and stops the timer while 

pressing the button next to CLR resets the timer to the 

programmed value.

2. To Reset the Integrated Timer, highlight and select the 

time under INTEG-T and Push[CLR]=0:00 appears 

on the display. Press the CLR button to the left of the 

display to reset the Integrated timer.

[TIMER] MODEL 2

2:03

INTEG-T

TIMER

 DOWN-T

 10:00

[TIMER] MODEL 2

INTEG-T

2:01

Push [CLR]=0:00

TIMER

 INH
MONITOR

A-48

The Monitor function displays each channel and shows 

the movement of channels when sticks, levers and 

switches are moved. It renames channels according 

to special assignments to assist in identifying what is 

moving. For instance, when Flaperon is the wing type, the 

Monitor will display RAIL for right Aileron and LAIL for 

left Aileron instead of displaying channel 2 and channel 

6. It is a handy way to determine what channels are mixed 

with other channels and to verify programming when the 

aircraft is not at hand. The Monitor function also displays 

the current value of all digital trims

1. To access the Monitor function, highlight and

select MONITOR in the FUNC.LIST to obtain 

the Monitor display.

2. The default display shows the settings of all channel 

positions and shows MONI in the upper left hand 

corner of the screen. To view the Monitor display of the 

digital trim positions, highlight and select TRIM. View 

the display while moving sticks, switches and levers to 

see the movements of various channels.

[MONITOR]

MONI THRO

AILE

ELEV

RUDD

GEAR

FLAP

AUX2

AUX3

AUX4
UTILITY FUNCTIONS

COPY – COPY THE CURRENTLY SELECTED MODEL TO ANOTHER MODEL MEMORY

A-49

The Copy function is part of the Model SEL function 

described earlier and allows the contents of the current 

model memory to be copied into another model memory 

in the same transmitter. It is not used to transfer the 

model to another transmitter or to a DataSafeTM unit – the 

TRANSFER function provides for these activities.

The Copy function is very valuable because it can provide 

some insurance against losing programs (aircraft setups) 

that may have been time-consuming to create. It is 

strongly recommended that the Copy function be used to 

make a backup copy of the model memory for safekeeping 

after programming for a model has been completed, tested 

and refined. 

Making a backup copy of the model memory protects 

against losing the original program and also allows one 

to experiment with the original program, knowing that the 

original settings can be restored by copying the backup 

copy back to the original model memory. 

1. The model to be copied must be currently selected – 

see Model SEL description at the beginning of the 

ACRO section.

The X9303 2.4 System includes two utility functions 

to help with managing the settings that have been 

programmed into the X9303 2.4 model memories. These 

functions include Copy and TRANSFER, both of which 

are located in the SYSTEM Menu. The Copy function 

is actually part of the Model SEL function while the 

TRANSFER function has its own set of displays.

Copy

[Model SEL]

MODEL 2 ACRO

COPY MODEL 3 HELI
COPY – COPY CURRENT MODEL (continued)

A-50

2. Highlight and select Model SEL in the 

SYSTEM Menu. Then highlight and select 

Select to obtain the Copy display.

3. Verify that the top model is the model that is to be 

backed-up and the lower model is empty or contains 

a model that is no longer required. When satisfied that 

all is correct, press the CLR button on the left side of 

the display next to COPY. The entire contents of the 

currently selected model are copied to the lower model 

on the display and there is now a complete backup of 

the current model. The upper and lower model memory 

names are now the same because the two model 

memories are now identical in every regard.

The backup copy can now be used to restore the 

original at any time by performing the Copy function and 

reversing the order of models where the backup is copied 

into the original (backup copy on the top line and the 

original model memory on the bottom line).

Note: As the X9303 2.4 has the ModelMatch feature, 

in order to operate the receiver on a new model 

number, you must first re-bind the receiver to the 

new model in order for it to function.

The display shows the currently selected model on top 

with a down-arrow pointing to the lower model memory 

that the current model will be copied into. The data that 

is presently in the lower model memory will be entirely 

replaced by the data in the currently selected model, so 

be sure that the lower model memory is either empty or 

contains data that is no longer required.

To change the lower model memory that is to 

receive the copy of the current model, highlight and 

select the lower model name and number. Then scroll to 

an unused model memory or a memory that contains data 

that is no longer required, and select it. 

Copy

[Model SEL]

MODEL 2 ACRO

MODEL 3 HELI SPCM MODEL 1 GLID

MODEL 3 HELI

MODEL 4 ACRO

Copy

[Model SEL]

MODEL 2 ACRO

COPY MODEL 3 HELI
TRANSFER – TRANSFER THE MODEL TO ANOTHER TRANSMITTER OR TO DataSafe

RECEIVE A MODEL INTO THE X9303 2.4 – (Transfer function)

A-51

1. Hold the ENT button while plugging the trainer cord 

into the back of the transmitter to obtain the 

SYSTEM Menu. 

Plug the other end of the trainer cord into another 

X9303 2.4 or XP9303 transmitter while holding the ENT 

button down and prepare that transmitter for Receive as 

described below. Or, plug the other end of the trainer cord 

into a DataSafe unit and prepare the DataSafe for Receive.

2. Highlight and select TRANSFER in the SYSTEM 

Menu to obtain the Transfer display.

The TRANSFER function can be found in the SYSTEM 

Menu and is used to copy the contents of a model 

memory to another X9303 2.4, XP9303 transmitter or 

to a DataSafe device on a Personal Computer (PC). It is 

also used to receive data for a model, either from another 

X9303 2.4, XP9303 transmitter or from a DataSafe unit.

3. The model to be transferred must be the currently 

selected model. If the model to be transferred is not 

currently selected, see Model SEL in the SYSTEM 

Menu to select the model to be transferred to another 

X9303 2.4, XP9303 or DataSafe unit.

4. When the receiving device is ready, press the CLR 

button next to START on the left side of the display. 

The data for the currently selected model is transferred 

to the receiving device.

[TRANSFER]

TRANSMIT

MODEL 2 ACRO

Connect DSC & POWER off

[TRANSFER]

TRANSMIT

MODEL 3 ACRO H9 EXTRA

Receiver stand-by?

START 0%
RECEIVE A MODEL INTO THE X9303 2.4 – (Transfer function)

A-52

1. Hold the ENT button while plugging the trainer cord 

into the back of the transmitter to obtain the SYSTEM 

Menu. Plug the other end of the trainer cord into 

another X9303 2.4 or XP9303 transmitter while 

holding the ENT button and prepare that transmitter 

for Transmit as described above. Or, plug the other end 

of the trainer cord into a DataSafe unit and prepare the 

DataSafe for Transmit.

2. Highlight and select TRANSFER in the SYSTEM 

Menu to obtain the Transfer display.

3. If RECEIVE is already displayed, continue with the 

next step. If TRANSMIT is displayed, highlight and 

select TRANSMIT, changing it to RECEIVE.

4. Select the model memory that is to receive the data by 

highlighting and selecting the model name/memory 

number and then scrolling to and selecting the model 

memory that is to receive the data. Be careful to select 

an unused model memory or a memory that contains 

data for a model that is no longer needed because the 

data in this model memory is going to be replaced by 

what is transmitted and will be permanently lost.

5. Press the CLR button next to START on the left side 

of the display. Stand-by appears at the bottom of 

the display indicating that the X9303 2.4 is ready to 

receive data. Press start on the transmitting X9303 2.4, 

XP9303 or DataSafe unit to begin the data transfer to 

the X9303 2.4 .

[TRANSFER]

RECEIVE

MODEL 3 HELI

MODEL 2

Connect DSC & POWER off

[TRANSFER]

RECEIVE MODEL 1 GLID

MODEL 3 ACRO

 4 ACRO

MODEL 2

[TRANSFER]

RECEIVE

STOP

MODEL 16 ACRO H9 EXTRA

MODEL 16

0%

Stand-by
SUB TRIM USAGE AND MECHANICAL ADVANTAGE

MECHANICAL ADVANTAGE

SUB TRIM

A-53

Sub Trims are intended for relatively minor adjustments 

to servo linkages and not for major trim adjustments to 

the aircraft. Using excessive sub trim percentages can 

cause a loss in servo travel in one direction, where the 

servo reaches its travel limit and stops moving before the 

control stick is fully deflected.

The diagram below illustrates an ideal servo/linkage setup 

when the servo is at neutral (no sub trim and digital trims 

centered). Notice that the servo arm is positioned at 90 ̊ 

or perpendicular to the servo. Also note that the linkage 

or rod is attached at 90 ̊ to both the servo arm and the 

control surface horn. This setup will result in the same 

amount of throw in both directions (0 differential throw). 

If the servo cannot be mounted parallel to the linkage/rod 

then just make sure the servo arm is at 90 ̊ to the control 

rod when the servo is at neutral.

Mechanical Advantage is a very important concept when 

dealing with larger aircraft. It refers to the leverage that 

the servo can exert on the control surface. Since the 

control surfaces are rather large, it is important for the 

servo to have enough mechanical advantage or leverage 

to control them, regardless of the servo’s rated torque. 

A large amount of torque is of little value if there is not 

enough leverage to use it. Insufficient leverage can lead to 

control surface flutter (usually a catastrophic event) and 

blow-back, where the air flow pushes the control surface 

backwards resulting in mushy or no control at higher 

speeds.

There are two ways to increase the mechanical advantage 

of the servo. One is to make sure that the control horn 

device, whether it be a horn as shown in the illustration 

above or a bolt with a ball-link fastener, is long enough. 

The horn is the lever that the servo uses to control the 

surface. The longer the horn, the more leverage the servo 

has.

The second way to increase the mechanical advantage 

for the servo is to attach the linkage at the servo arm as 

far inward (towards the servo arm retaining screw) as 

possible while still providing enough throw. This takes 

leverage away from the control surface by providing it 

with a shorter lever to work against the servo. 

Ensure that the attach point is the same distance from the 

hinge line for like surfaces (two Ailerons, two Elevators 

and two Rudder horns). If the attach points are not the 

same distance from the hinge line there will be unequal 

throw and it will be more difficult to synchronize the 

surfaces for equal deflection. This is especially critical 

for the Rudder where two servos are attached to the same 

surface – unequal throw will cause the servos to fight one 

another causing excessive battery drain, and in severe 

cases may cause servo damage.

Always try to use the maximum amount of Travel (100%) 

that the radio provides. Don’t reduce the percentage of 

travel in the radio. Instead, move the linkage further away 

from the hinge line at the control surface and/or move 

the linkage inward on the servo arm or use a shorter 

arm. If you use high percentages of travel, you maintain 

resolution (fine movements of the stick result in fine 

positive movements of the control surface).

Linkage is 90 degrees 

to control horn

Linkage is 90 degrees to servo arm

Servo arm is 90 degrees to servo

Greater 

Mechanical 

Advantage

Greater 

Mechanical 

Advantage
DUAL RATES AND EXPONENTIAL CURVES

A-54

Dual Rates and Exponential curves can be very effective 

in setting up an aircraft to “feel” the way you would like 

it to feel when performing different types of maneuvers. 

You can essentially change the aircraft’s personality just 

by flipping a switch, causing the aircraft to take on traits 

that make certain maneuvers easier for the pilot. At times 

you may want the aircraft to feel very crisp, such as when 

performing point rolls and sided-loops and then feel 

softer for other maneuvers, such as rolling circles and 

consecutive rolls, and yet other times when you would like 

the aircraft to be very crisp but without a the tendency to be 

over-controlled, like in performing snap rolls. Dual Rates 

and Exponential curves can be combined to produce these 

traits for most any aircraft. When programming a Dual Rate 

and Exponential curve, always think about what kind of 

maneuver or flying style you plan to accomplish with it.

Dual Rates (D/R) limit how far a control surface travels. 

Without dual rates your control surfaces deflect to their 

full travel – the travel that you previously established with 

the TRVL ADJ. function and linkage setup. When a D/R is 

programmed, it limits the amount of deflection that occurs 

when the stick is moved to its extremes. For example, if 

you set an Elevator D/R to 75%, the Elevator will only 

deflect 75% or 3/4 of its full travel; if set to 50%, it will be 

limited to 1⁄2 of its full travel; and so forth. A D/R setting of 

100% results in full travel again, as though there were no 

D/R programmed at all. 

An example of programming a D/R for the Ailerons

would be to set up an Aileron D/R for flying consecutive 

rolls by setting the Aileron D/R to 25% (actual percentage 

will vary). At this setting, moving the Aileron stick full 

left or full right would result in a roll rate of about 1 roll 

per second. This allows you to deflect the Aileron stick 

all the way and just hold it there while concentrating on 

Elevator and Rudder inputs – flying consecutive rolls

just became easier.

EXPONENTIAL (EXP) does not limit the total deflection 

of a servo/control surface – the surface still moves 

100% of its travel. It does, however, determine how the 

surface reaches its full travel, or how the control surface 

moves relative to the stick. When Exponential is not used, 

the servo response is said to be linear. That is, every 

movement of the stick causes the same movement in the 

servo--if the stick moves 20%, the servo moves 20% and 

the control surface follows the stick throughout the entire 

travel range. When plotted on a graph where the X-axis 

(left and right) = stick movement and the Y-axis (up and 

down) = servo movement, the result is a straight line that 

is at 45 degrees.

When using Exponential, a positive (+) exponential 

percentage causes the servo to move less when the stick 

is close to the neutral point, and to move more as the 

stick moves further from the neutral point. For instance, 

the stick is moved from neutral to 30% and the servo 

only moves from neutral to 10%. As the stick is moved 

further from center (from 30% to 50%), the servo moves 

further and faster (from 10% to 35%). The further the 

stick is moved away from center, the higher the rate of 

servo movement. The larger the positive (+) Exponential 

percentage, the further the stick must be moved from 

center before the servo rate increases, and the faster the 

servo rate becomes when it gets close to the end of its 

travel. When stick travel (left and right) versus servo 

travel (up and down) is plotted on a graph, the result is a 

“curve.” The curve stays close to the X-axis at the center 

(small servo movement) and moves away from the X-axis 

at a greater rate (more servo movement) as the stick is 

moved further off center.

Exponential is typically used to reduce sensitivity or 

otherwise dampen movements around the neutral stick 

position without sacrificing full servo travel. This provides 

the pilot with very smooth and precise control of the 

aircraft while allowing relatively large movements in the 

control stick. It becomes easier to make very smooth and 

precise corrections that are difficult to detect.

If negative exponential is used, it has the opposite effect. 

Servo travel is increased around center and slows towards 

the ends. Care must be taken with negative exponential, 

as an aircraft that is already overly sensitive may become 

uncontrollable with negative exponential. It can prove 

useful, however, when hovering a 3D type aircraft.

No Exponential

Exponential
Setup Sheet (Aircraft)

A-55

MODEL NO

MODEL NAME

SPOI AIL1 ELEV RUDD AIL2 FLAP AUX2 AUX3

REVERSE SW

SUB TRIM

TRAVEL ADJUST

AILE ELEV RUDD

DUAL RATE/EXP

0

1

D/R

EXP

D/R

EXP

%

%

%

%

%

%

%

%

%

%

%

%

DIFFERENTIAL %

NORM

REV

NORM

REV

NORM

REV

NORM

REV

NORM

REV

NORM

REV

NORM

REV

NORM

REV

+ %

- %

L %

R %

U %

D %

L %

R %

+ %

- %

+ %

- %

L %

R %

U %

D %

PROGRAMMABLE

MIX

MIX1

MIX1

MIX1

MIX1

MIX1

MIX1

CHANNEL SW EXP 0 1 2 3 4 5 6

ON/OFF

+POS -POS OFFSET

ON/OFF

ACT

INH

SNAP ROLL

R-D

R-U

L-D

L-U

%

%

%

%

%

%

%

%

%

%

%

%

TRIM OFFSET

AUTO RUDD D/R ACT INH

ELEV FLAP

MIX

DOWN

UP

%

%

AILE RUDD

MIX

RATE

SW

%

%

ACT INH

ELEV

FLAP

SPOI

AUTO

LANDING

THRO

WING TYPE

NORMAL

FLAPERON

DELTA

ADDITIONAL

NOTES
A-56
X9303 2.4 Helicopter – Heli Mode

Heli PROGRAMMING - PLEASE READ

HELI - GETTING STARTED – SYSTEM MENU BASICS

H-1

INTRODUCTION

The Heli mode of the X9303 2.4 system is intended for 

use in model helicopters with all types of Swashplate 

mixing. It contains a host of advanced features that are 

easy to set up and use. The features have been designed 

to assist the pilot in realizing the full potential of the 

helicopter. These features include:

• Switch Assignments for Specific Channels/

Functions

• Flight Modes (up to 6)

• Dual Rates/Exponential (up to 3 settings each for 

Aileron, Elevator and Rudder)

• Swashplate Type (Normal, 120, 140, and

90 CCPM)

• Adjustable Trim Rates (10 – 100 Trim Steps)

• Built-In Cyclic-to-Throttle Mixing for Aileron, 

Elevator, and Rudder

• Governor Pre-Program Mix

• Throttle Curves (up to 5) with up to 7 Points 

• Pitch Curves (up to 6) with up to 7 Points 

• Gyro System (In Flight Gain Selection of

up to 3 Gains)

• 6 Programmable Mixes (Includes 2 Multi-Point and 

4 Standard Mixes)

• Fail-Safe (Hold or Predetermined Positions)

•Trainer System (Selectable Channels for

Student Control)

• Timers (Stopwatch, Count-Down, Integrated)

• Servo Monitor (Automatically Renames Channels 

According to Assignments)

In addition to the numerous features listed above, the 

X9303 2.4 provides the ability to combine, activate, and 

deactivate multiple features such as Dual Rates,Gyro Gain, 

and Governor settings, using the Flight Mode switch. 

This capability dramatically reduces the pilot’s workload, 

allowing the pilot to focus on the task of flying.

Those who are comfortable with programming are still 

encouraged to continue reading this part of the manual in 

order to acquire an understanding of the basic X9303 2.4 

programming philosophy, functions, and techniques. 

This section of the manual begins with entering the 

System Menu, selecting a model and activating the HELI 

Mode, and progresses through the remainder of the 

System Menu options and then through the individual 

functions. The descriptions here are general in nature and 

serve not only to identify the functions that are available, 

but why the functions are included in the HELI Mode and 

when a particular function should be used. 

Those who have some experience with computer radios 

will probably be able to program their helicopter as 

they read through this section, owing to the fact that the 

individual functions are generally simple in nature and the 

X9303 2.4 is a very intuitive system. 

Getting started begins with accessing the SYSTEM Menu. 

This is where models are selected, the mode is identified, 

modulation type is indicated, and where other high-level 

information is stored for the model. It is also used to activate 

some of the more advanced programming features such as 

Swashplate Types and Governor Program activation.
ACCESS THE SYSTEM MENU

Model SEL- Model Selection

H-2

The first thing to do when setting up a new model is to 

select the model to be used. It is best to select an unused 

model number, however, a model that already contains 

data for another model may be used so long as data 

for that model is no longer required. If the model type 

is changed before deciding the model to be used, any 

programming in this particular model will be lost.

1. Bring up the SYSTEM Menu by holding down the 

ENT button while turning the transmitter on.

1. In the SYSTEM Menu, highlight and select Model 

SEL using the Selector.

2. Use the Selector to highlight and select the desired 

model number to be used.

3. Return to the SYSTEM Menu by pressing the

LIST button.

INFO-DISP

Model SEL

MDL Name

Type SEL

MDL Reset

TRANSFER

TRIM STEP

Devic. SEL

SWASH TYP

[SYSTEM M.]

Select 1 GLID

 2 ACRO

MODEL 3 MODEL 3 HELI

 4 ACRO

 5 GLID

[Model SEL]
Copy – Copying the Currently Selected Model to Another Model Memory

H-3

The Copy function is part of the Model SEL function 

and allows the contents of the current model memory 

to be copied into another model memory in the same 

transmitter. It is not used to transfer the model to another 

transmitter or to a Data Safe unit – the DATA TRANSFER 

function provides for these activities.

The Copy function is valuable because it can provide 

some insurance against losing programs (helicopter 

setups) that may have been very time-consuming to 

create. It is strongly recommended that the Copy function 

be used to make a backup copy of the model memory 

for safe keeping after programming for a model has been 

completed, tested and refined.

Making a backup copy of the model memory protects 

against losing the original program and also allows one 

to experiment with the original program, knowing that the 

original settings can be restored by copying the backup 

copy back to the original model memory. 

1. The model to be copied must be currently selected 

– see Model SEL description at the beginning of the 

HELI section.

2. Highlight and select Model SEL in the SYSTEM Menu. 

Highlight and select Select to obtain the Copy display.

The display shows the currently selected model on top 

with a down arrow pointing to the lower model memory 

that the current model will be copied into. The data that 

is presently in the lower model memory will be entirely 

replaced by the data in the currently selected model, so be 

sure that the lower model is either empty or contains data 

that is no longer required.

Copy

[Model SEL]

MODEL 3 HELI

COPY MODEL 4 HELI

Copy

[Model SEL]

MODEL 3 HELI

COPY MODEL 4 HELI
Copy (continued)

H-4

3. Verify that the top model is the model that is to be 

backed-up and the lower model is empty or contains 

a model that is no longer required. When satisfied 

that all is well, press the CLR button on the left side 

of the display next to COPY. The entire contents of the 

currently selected model are copied to the lower model 

on the display and there is now a complete backup of 

the current model. The upper and lower model memory 

names are now the same because they are now 

identical in every regard.

The backup copy can now be used to restore the original at 

any time by performing the Copy function and reversing the 

order of models where the backup is copied into the original.

Note: As the X9303 2.4 has the ModelMatch feature, 

in order to operate the receiver on a new model 

number, you must first re-bind the receiver to the 

new model in order for it to function.

To change the lower model memory that is to receive the 

copy of the current model, highlight and select the lower 

model name and number. Then scroll to an unused model 

memory or a memory that contains data that is no longer 

required, and select it.

Copy

[Model SEL]

MODEL 3 HELI

MODEL 3 HELI SPCM MODEL 2 ACRO

MODEL 4 HELI

MODEL 5 ACRO
Data Reset – RESET THE MODEL

H-5

When setting up a new model it is important to reset 

all parameters to their default or factory settings before 

proceeding with any other programming. This is to ensure 

that there are no program mixes, trims or other surprises 

left over from a previous model or programming session. 

If you are setting up a model for the first time, you can 

skip this step and move to the TYPE SELECT function.

1. In the SYSTEM Menu, highlight and select MDL 

Reset using the Selector.

2. Press the CLR button that is next to RES

on the display.

3. Press the lowermost button next to YES on the display 

to reset all data for this model.

4. Return to the SYSTEM Menu by pressing the

LIST button.

[MDL Reset]

LST

NO

YES

MODEL 3 HELI

Are you sure? Y/N
Type Select – TO ACTIVATE THE HELI MODE

MDL Name-ENTER A NAME FOR THE MODEL

H-6

1. In the SYSTEM Menu, highlight and select Type 

SEL using the Selector.

2. Highlight and select HELI using the Selector.

Each model should be given a name to make it easy 

to identify in the model number list and to identify the 

current model on the main display screen. The model 

name appears in the upper right-hand corner of the main 

screen when the transmitter is switched on.

3. Return to the SYSTEM Menu by pressing the

LIST button.

1. In the SYSTEM Menu, highlight and select MDL 

Name using the Selector.

2. Highlight and select the desired characters to form the 

model name.

After having selected and reset the desired model number 

to be programmed, it is time to tell the transmitter that the 

Heli Mode is to be used for this helicopter. 

3. Return to the SYSTEM Menu by pressing the

LIST button.

[Type SEL] MODEL 3 HELI

GLID ACRO HELI

 MODEL 3 HELI <VIBE 50>

[MDL Name]
TRANSFER A MODEL FROM THE X9303 2.4 – (Transfer function) – To Send

TRANSFER – TRANSFER THE MODEL TO ANOTHER TRANSMITTER OR TO DATASAFE

H-7

1. Hold the ENT button while plugging the trainer 

cord into the back of the transmitter to obtain the 

SYSTEM Menu. Plug the other end of the trainer 

cord into another X9303 2.4 or XP9303 transmitter 

while holding the ENT button down and prepare that 

transmitter for Receive as described below. Or, plug the 

other end of the trainer cord into a DataSafe unit and 

prepare the DataSafe for Receive.

2. Highlight and select TRANSFER in the SYSTEM Menu 

to obtain the Transfer display.

3. The model to be transferred must be the currently 

selected model. If the model to be transferred is not 

currently selected, see Model SEL in the SYSTEM 

Menu to select the model to be transferred to another 

X9303 2.4, XP9303 or DataSafe unit.

The TRANSFER function can be found in the SYSTEM 

Menu and is used to copy the contents of a model 

memory to another X9303 2.4, XP9303 transmitter or 

to a DataSafe device on a Personal Computer (PC). It is 

also used to receive data for a model, either from another 

X9303 2.4, XP9303 transmitter or from a DataSafe unit.

4. When the receiving device is ready, press the CLR 

button next to START on the left side of the display. 

The data for the currently selected model is transferred 

to the receiving device.

[TRANSFER]

TRANSMIT

 MODEL 3 HELI

Connect DSC & POWER off
TRANSFER A MODEL TO THE X9303 2.4 – (Transfer function) – To Receive

H-8

1. Hold the ENT button while plugging the trainer cord 

into the back of the transmitter to obtain the SYSTEM

Menu. Plug the other end of the trainer cord into 

another X9303 2.4 or XP9303 transmitter while 

holding the ENT button and prepare that transmitter 

for Transmit as described above. Or, plug the other end 

of the trainer cord into a DataSafe unit and prepare the 

DataSafe for Transmit.

2. Highlight and select TRANSFER in the SYSTEM Menu 

to obtain the Transfer display.

3. If RECEIVE is already displayed, continue with the next 

step. If TRANSMIT is displayed, highlight and select 

TRANSMIT, changing it to RECEIVE.

4. Select the model memory that is to receive the data by 

highlighting and selecting the model name/memory 

number and then scrolling to and selecting the model 

memory that is to receive the data. Be careful to select 

an unused model memory or a memory that contains 

data for a model that is no longer needed because the 

data in this model memory is going to be replaced by 

what is transmitted and will be permanently lost.

Note: The receiving model name/memory number 

can not be the currently selected model. If you wish to 

receive a model in the currently selected model name/

memory number, go to the model select function and 

select a different model, then re-enter the transfer 

function and follow the instructions above.

5. Press the CLR button next to START on the left side 

of the display. Stand-by appears at the bottom of 

the display indicating that the X9303 2.4 is ready to 

receive data. Press start on the transmitting X9303 2.4, 

XP9303 or DataSafe unit to begin the data transfer to 

the X9303 2.4.

[TRANSFER]

RECEIVE

MODEL 4 HELI

MODEL 3

Connect DSC & POWER off
TRIM STEP

H-9

The Trim Step function provides for adjusting the 

sensitivity of the X9303 2.4 trim levers and switches. It is 

useful during and after initial trimming of the helicopter 

in order to trim the helicopter quickly at first, and then 

to make very precise adjustments to helicopter trim. The 

digital trims may have a setting of 0–10 with 10 being the 

coarsest adjustment. When the value is set to 10, there are 

only 10 trim increments from center to each end. When 

set to 5, there are 20 trim increments from center to each 

end. When set to 4, there are 25 increments. When set to 

3, there are 34 increments, and when set to 1, there are 

100 trim increments! When set to 0 the trim levers cease 

to function and can no longer be used to change the trim 

of the helicopter.

When adjusting the digital trims (AILE, ELEV, RUDD, 

HOVT, HOVP), the total trim travel does not change – only 

the number of increments (beeps) changes, which makes 

for finer or coarser trim movements. When adjusting 

the analog throttle trim, however, the total trim travel is 

actually reduced when set to less than 100%.

Use a fairly coarse setting, such as the factory default 4, 

when test flying the helicopter in order to be able to trim 

it quickly, and then use a finer setting, such as 3–1, for 

final precision trimming. The exception to this would be 

for Rudder. Since most Gyros amplify the servo’s travel 

and sensitivity, a trim value of 1 or 2 for the Rudder trim 

usually achieves the best results.

1. Highlight and select TRIM STEP in the SYSTEM Menu 

to acquire the TRIM STEP display.

2. Highlight and select the trim that is to be changed and 

use the Selector to set a value of 1–10

(1 = finest, 10 = coarsest).

3. Repeat for other trims as desired.

[TRIM STEP]

THRO 100%

AILE 4

ELEV 4

RUDD 4

HOVT 4

HOVP 4
HELI - SYSTEM MENU - ADVANCED FUNCTIONS

ADDITIONAL FLIGHT MODES 3 and 4

H-10

There are two functions in the SYSTEM Menu that

control some of the more advanced features of the X9303 

2.4 system. They are the Devic. SEL and

Swash Type functions.

The Devic. SEL function is used to activate and deactivate 

2 additional Flight Modes; change switch assignments 

from the system defaults; activate and deactivate switches/

channels and to activate/deactivate the Hover Throttle, 

and Hover Pitch levers, and to Activate/Deactivate the 

Governor function.

The Swash Type function is used to indicate the 

Swashplate type (Normal (1 Servo), CCPM 180, 120, 140, 

and both 3 and 4 servo 90).

Each of the options in these two functions is described 

below to the extent necessary to determine if they should 

be used for the helicopter being programmed.

The X9303 2.4 is capable of offering the pilot up to 6 

separate flight modes. The X9303 2.4 is factory preset to 

offer the pilot 4 separate Flight Modes (N, 1, 2, H). There 

are 2 additional flight modes, numbered 3 and 4, that can 

be activated through the Device Select function.

If the additional flight modes are desired, please follow 

the activation procedure below.

To Activate 2 Additional Flight Modes 

(Flight Modes 3 and 4)

1. From the SYSTEM Menu highlight and select Devic. 

SEL by using the Rolling Selector.

2. Highlight and select F.MOD Extra using the Rolling 

Selector. When selected, five options appear: AIL D/

R, ELE D/R, RUD D/R, HOLD SW, and GEAR SW. 

Highlight and select the switch that is to be used to 

access Flight Modes while flying. The example below 

shows that the GEAR switch has been selected.

Once Flight Modes have been activated, two additional 

sets of Throttle and Pitch curves numbered 3 and 4 will 

appear in the Function Mode. 

RUD TRIM:COM

GEAR AUX2 AUX3 AUX4

GEAR AUX2 AUX3 FMOD

 SW SW LEV SW

OUT: ACT ACT ACT ACT

[Devic. SEL]

F.MOD THRO Pit.

EXTRA HOLD TRIM

INH HOLD PitT

SW LEV

RUD TRIM:COM

GEAR AUX2 AUX3 AUX4

GEAR AUX2 AUX3 FMOD

 SW SW LEV SW

OUT: ACT ACT ACT ACT

[Devic. SEL]

F.MOD THRO Pit.

EXTRA HOLD TRIM

INH HOLD PitT

SW LEV INH RUD D/R

AIL D/R HOLD SW

ELE D/R GEAR SW
RUD TRIM: COM – (Flight Mode Trim Options)

SWITCH ASSIGNMENTS

H-11

The Rud Trim function is designed to allow the pilot to 

choose between 1 set of trim settings for the Rudder 

channel only in all flight modes (COM) or a separate set 

of trim settings for each of the flight modes (FM).

The RUD TRIM: COM parameter can be toggled back 

and forth between COM and FM by pressing the Rolling 

Selector when COM or FM is highlighted. If left in 

the COM mode, the digital trim for rudder is Common 

or shared by the 3 Flight Modes. If FM is selected, the 

X9303 2.4 keeps track of the digital trims independently 

for each Flight Mode, which means the pilot can re-trim 

the rudder using the digital trims for each Flight Mode. 

To change one or more switch assignments:

1. From within the Devic.SEL function, use the 

Selector to highlight and select THRO HOLD, PIT 

Trim, GEAR, AUX2, AUX3, or AUX4 along the top 

line of the display.

2. Once a switch is selected, a list of available 

replacement switches is displayed. Highlight and select 

the desired switch with the Selector.

The X9303 2.4 provides the ability to change the 

standard default switch assignments for THRO Hold, 

PIT Trim, GEAR, AUX2, AUX3, and AUX4. Changing the 

assignments may be a matter of preference or to help 

overcome a disability in one hand. In any event, the 

standard switch assignments may be changed in Devic.

SEL function contained in the SYSTEM Menu.

3. Repeat for as many switches as desired.

[Devic. SEL]

F.MOD THRO Pit.

EXTRA HOLD TRIM

INH HOLD PitT

SW LEV

RUD TRIM:FM OUT: ACT ACT ACT ACT

GEAR AUX2 AUX3 FMOD

 SW SW LEV SW

GEAR AUX2 AUX3 AUX4

RUD TRIM:COM

GEAR AUX2 AUX3 AUX4

GEAR AUX2 AUX3 FMOD

 SW SW LEV SW

OUT: ACT ACT ACT ACT

[Devic. SEL]

F.MOD THRO Pit.

EXTRA HOLD TRIM

INH HOLD PitT

SW LEV

AIL D/R HOLD SW

ELE D/R GEAR SW

RUD D/R
ACTIVATE/DEACTIVATE SWITCHES

GOVERNOR PROGRAM ACTIVATION

H-12

The X9303 2.4 provides the ability to disable a number of 

the switches on the transmitter – Pit TRIM, GEAR, AUX2, 

AUX3, and AUX4. This is very useful when auxiliary 

channels are used for special or mixing purposes. In 

this instance, the auxiliary channels are no longer to be 

operated by their auxiliary switches but rather the program 

mix selected or transmitter sticks. 

1. If PIT TRIM, GEAR, AUX2, AUX3, or AUX4 are to be 

used as a 2nd primary flight control, then inhibit the 

corresponding switch by highlighting ACT, along the 

bottom line of the display and pressing the Selector

until INH appears under the switches that are to be 

turned-off. The example below shows all switches as 

INH or being turned-off, making them all available to 

be used as a 2nd channel for a primary flight control.

The X9303 2.4 features a special Governor program that 

can be activated in the Device Select screen.

The Governor program is designed to be used with 

most currently available Governor systems, and 

allows for independent rpm settings for each of the 

active flight modes.

1. From within the Devic.SEL function use the Selector

to highlight and select OUT:ACT located at the bottom of 

the GEAR column along the bottom line of the display.

2. Press the Selector until the word GOV appears on 

the display. This indicates that the Governor function 

has been activated. The Governor program will now be 

visible in the Function Mode List.

[Devic. SEL]

F.MOD THRO Pit.

EXTRA HOLD TRIM

INH HOLD PitT

SW LEV

OUT: INH INH INH INH

GEAR AUX2 AUX3 AUX4

GEAR AUX2 AUX3 FMOD

 SW SW LEV SW

RUD TRIM:COM

[Devic. SEL]

F.MOD THRO Pit.

EXTRA HOLD TRIM

INH HOLD PitT

SW LEV

RUD TRIM:COM

GEAR AUX2 AUX3 AUX4

GEAR AUX2 AUX3 FMOD

 SW SW LEV SW

OUT: GOV INH INH INH
SWASH TYP-SWASHPLATE TYPE

Accessing the Swashplate Type Function

H-13

1. While pressing the ENT key, switch the transmitter to 

the ON position to enter the system mode. 

2. Roll the Rolling Selector until SWASH TYP

is highlighted, then press the Selector

to access.

3. Press the Rolling Selector again, and the screen 

will display the available swashplate types. Move the 

Selector to highlight the desired swashplate type, and 

then press the Selector to select.

4. Pressing the CLR key will reset the Swashplate Type to 

the factory default (Normal) position.

5. To exit the Swashplate Type function, roll the Rolling 

Selector to highlight LIST, and press.

This concludes the SYSTEM Menu portion of the Heli 

Mode. Continue with FUNCTION LIST below to complete 

the Heli setup.

The Swashplate Mixing function enables the X9303 2.4 

system to operate many different types of swashplate 

control systems, including 5 different versions of CCPM.

The Swashplate options are:

1 Servo Non-CCPM, standard mixing type

2 Servo/180° CCPM

3 Servo/120° CCPM (JR style, most popular)

3 Servo/140° CCPM (JR Vigor CS, JR Vibe 90)

3 Servo/90° CCPM

4 Servo/90° CCPM

[SWASH TYPE]

3servos

140

6ch 2ch

3ch
HELI – FUNCTION LIST

D/R & EXP – DUAL RATE AND EXPONENTIAL

FUNCTION MODE

H-14

Once the basic helicopter configuration has been 

defined in the SYSTEM Menu, the functions found in the 

FUNCTION LIST are used to complete the setup and then 

to adjust how the helicopter flies and how it is controlled. 

The functions are presented below in the order that they 

appear in the Function List. 

The descriptions are general in nature and are intended to 

provide enough information to decide whether or not to 

use a function, and what types of selections and settings 

to make.

Press the LIST button after the transmitter is powered-up 

to obtain the FUNCTION LIST.

Dual Rates and Exponential curves can be very effective 

in setting up a helicopter to have a particular “feel” when 

performing different types of maneuvers. Just changing 

D/R and EXPO values can change the helicopter’s 

personality, causing the helicopter to take on traits that 

make certain maneuvers easier for the pilot. At times we 

may want the helicopter to feel very crisp, such as when 

performing aerobatics, and then feel softer for other 

maneuvers such as Hovering, and yet other times when 

we would like the helicopter to be very crisp but without 

the tendency to be over-controlled, like in performing 3D 

maneuvers. Dual Rates and Exponential curves can be 

combined to produce these traits. When programming a 

Dual Rate and Exponential curve, think about what kind of 

response is desired from the helicopter.

1. Highlight and select D/R & EXP in the FUNC.LIST

to obtain the D/R & EXP display. There will be 3 sets of 

values displayed for each channel – Aileron, Elevator 

and Rudder. 

2. Use the Selector to change between Aileron, 

Elevator and Rudder. Then use it to set dual rate and 

exponential values. If exponential has never been used 

before, try a low positive value like +20. After a while, 

increase it gradually until the desired feel is obtained. 

Use only positive (+) percentages unless there is a 

distinct need to increase control sensitivity.

D/R EXP

100% LIN

100% LIN

100% LIN

100% LIN

100% LIN

100% LIN

[D/R & EXP]◊0

POS-0

POS-1

POS-2

AILE

AUTO

NORM:INH

ST-1:INH

ST-2:INH

HOLD:INH

D/R EXP

100% LIN

100% LIN

100% LIN

100% LIN

100% LIN

100% LIN

[D/R & EXP]◊0

POS-0

POS-1

POS-2

AILE

OUTPUT

Extended Screen
REV.SW - SERVO REVERSING 

Auto Dual Rate

H-15

Once all servos have been plugged into their proper 

channels in the receiver, the first thing to check is the 

direction of travel of each servo. Move all sticks and 

switches/levers while observing each servo to determine 

if the servos are moving in the correct directions. Make 

note of those servos that are not traveling in the correct 

direction and use the REV.SW function to reverse the 

direction of travel for these servos.

1. Highlight and select REV.SW in the FUNC.LIST to 

obtain the servo reversing display.

2. Use the Selector to highlight and select those 

channels that need to be reversed. Pressing the 

Selector toggles the channel between Normal 

and Reverse.

Note: If any of the versions of CCPM have been 

selected, the 3 CCPM channels will be re-named to 

CH2, CH3, and CH6, etc. on the display.

The Automatic Dual Rate function allows you the 

opportunity to change the dual rate and expo values of the 

elevator, aileron, and rudder by changing the flight mode 

or throttle hold switch positions.

This feature simplifies the operation of multiple switches 

during flight.

To access the Auto D/R feature, simply roll the selector to 

the right until the D/R Expo graph is replaced by the Auto 

D/R Flight Mode list.

 Highlight the Flight Mode to be set for Auto D/R, then 

press the selector to pick the desired D/R setting to be 

used for this flight mode. Repeat as necessary to assign 

D/R positions for each flight mode.

[REV SW.]

THR AIL ELE RUD GER PIT AX2 AX3 AX4

REV.

NORM

[REV SW.]

THR CH2 CH3 RUD GER CH6 --- AX3 AX4

REV.

NORM
Sub Trim

H-16

Sub Trims are intended for relatively minor adjustments 

to servo linkages and not for major trim adjustments to 

the helicopter. Using excessive sub trim percentages can 

cause a loss in servo travel in one direction where the 

servo reaches its travel limit and stops moving before the 

control stick is fully deflected.

Use Sub Trims to fine-tune the alignment of servo arms. 

Install servo arms on the servos so that the arms are at 

90 ̊ or perpendicular to the servo case/linkage. As JR 

servos feature an odd number of splines on the output 

shaft, you can rotate and reinstall the arms to try and 

obtain a better position for the servo arm that will require 

a lesser amount of sub trim. Now use the Sub Trim 

function to fine-tune the servo arms that are not quite at 

90 ̊ to the servo.

1. Highlight and select Sub Trim in the FUNC.LIST to 

obtain the Sub Trim Display.

Note: If a form of CCPM has been selected, channel 

naming will vary.

2. Highlight and select the channels where the servo arms 

are not quite at the desired position. Once a channel is 

selected, rotate the Selector until the servo arm is at 

90 ̊ to the servo case.

[Sub Trim]

THRO 0 GEAR 0

AILE 0 PIT. 0

ELEV 0 AUX2 0

RUDD 0 AUX3 0

 AUX4 0
TRVL ADJ. – TRAVEL ADJUST

H-17

Travel Adjust is used to adjust how far a servo travels in 

each direction. After the linkages have been installed and 

attached to the servos, adjust the amount of servo travel 

in each direction.

1. Highlight and select TRVL ADJ. in the FUNC.LIST

to obtain the Travel Adjust display.

2. Use the Selector to highlight and select each channel 

and adjust the travel in each direction by rotating the 

Selector. The direction of travel is changed by moving 

the stick/switch/lever back and forth.

Note: If a form of CCPM has been selected, channel 

naming will vary.

[TRVL ADJ.]

THRO H100% L100% GEAR 

AILE L100% R100% PIT.

ELEV D100% U100% AUX2

RUDD L100% R100% AUX3

 AUX4

+100% -100%

H100% L100%

+100% -100%

+100% -100%

+100% -100%
Swash Mix- CCPM SWASHPLATE Mixing 

H-18

1) Normal (Standard Mechanical Mixing)

This form of Swashplate Mixing uses each of the three 

servos to move the swashplate individually for pitch, 

Aileron, and Elevator changes. If one servo (NORM) 

is selected in the System Mode (Factory Default), the 

Swashplate Type function will not appear on the LCD 

screen in this section.

2) 2-servo 180 degrees

2 servos are used to move the swashplate, and 

are spaced at 180 degrees apart. This is not a very 

common control system configuration.

3) 3-servo 120 degrees 

3 servos are used to move the swashplate, and are spaced 

at 120 degrees apart. This is the most common form of 

CCPM, and is found in JR and other brands of helicopters.

4) 3-servo 140 degrees 

3 servos are used to move the swashplate, and 

are spaced at 140 degrees apart. This is a special 

JR developed form of CCPM, and is found in 

JR Vibe helicopters.

5) 3-servo 90 degrees

3 servos are used to move the swashplate, and are 

spaced at 90 degrees apart. This is also not a very 

common control system configuration.

6) 4-servo 90 degrees

4 servos are used to move the swashplate, and are 

spaced at 90 degrees apart. This is a very common 

control system configuration, used predominantly for 

Scale models like Vario, Graupner, etc.

This section is for those that have activated CCPM 

Swashplate mixing. If CCPM Mixing has not been 

activated, skip to Throttle Hold/ThrottleCurves)

Note: The CCPM Swashplate Mixing screen is only 

displayed when Swashplate types 2s 180, 3s 120, 3s 

140, 3s 90 or 4s 90 are selected in the Swashplate 

type Selection in System Mode.

The CCPM Swashplate Mixing function (Cyclic Collective 

Pitch Mixing) of the X9303 2.4 is designed to allow the 

X9303 2.4 to be used in model helicopters that utilize 

2-servo (180°), 3-servo (120°), 3-servo (90°) type and 

4-servo (90°) swashplate control systems.

The desired swashplate mixing type must first be selected 

at the Swash Type Selection in System Mode.

Variations of CCPM Mixing

2-servo (180°) 

Ch 2&6 Aileron Ch 3 Elevator Ch 6 Pitch

3-servo (90°) 

Ch 2&6 Aileron Ch 3 Elevator Ch 2,3&6 Pitch

3-servo(120°) 

Ch 2&6 Aileron Ch 2,3&6 Elevator Ch 2,3&6 Pitch

CCPM Servo Connection/Channel Numbers

3-servo (140 ̊) 

Ch 2&6 Aileron Ch 2, 3&6 Elevator Ch 2,3&6 Pitch

4-servo (90 ̊) 

Ch 2&6 Aileron Ch 3&8 Elevator Ch 2,3,6&8 Pitch

[Swash Mix]

3servos

140o

AILE 60%

ELEV 60%

PIT. 60%

EXP INH