RadioLink F121 User manual

Radiolink Electronic Ltd
www.radiolink.com
F121
Mini Racing Drone
Altitude Hold by Inertial Navigation
User Manual
* Please be kindly noted that this manual will be updated regularly and please visit RadioLink
official website to download the latest version：www.radiolink.com
V 1.0

Radiolink Electronic Ltd
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Thank you for purchasing RadioLink mini racing drone F121.
To fully enjoy the benefits of this product and ensure safety, please read the manual carefully and set up the device
as instructed steps.
If any problems found during the operation process, either way listed below can be used as online technical
support.
1. Send mails to [e-mail] or [e-mail] and we will answer your
question at the earliest.
2. Send message to us on our Facebook page or leave comments on our YouTube page
3. If purchased from an approved dealer or distributor, you can contact them directly for support.
All manuals and firmwares are available on RadioLink official website www.radiolink.com and more tutorials are
uploaded. Or follow our Facebook and YouTube homepage to stay tuned with our latest news.
⚫Never operate models during adverse weather conditions. Poor visibility can cause disorientation and loss of
control of pilots model.
⚫Never use this product in a crowd or illegal areas.
⚫Always ensure the trim levers at 0 and battery properly charged before connecting the receiver.
⚫Always check all servos and their connections prior to each run.
⚫Stay at a certain distance from the aircraft during flight to avoid getting hurt by the components of high-speed
rotation (eg. Props, brushless motors)
⚫After landing off, make sure the aircraft is disarmed and props have stopped moving before getting close to touch
the aircraft.
⚫Always be sure about turning off the receiver/powering off the aircraft before the transmitter.
⚫Follow the instructions of props installation in case of dropping during flight.
⚫To ensure the best radio communication, please enjoy the flight at the space without interference such as high
voltage cable, communication base station or launching tower.
This product is not a toy and is NOT suitable for children under the age of 14. Adults should keep the product out of
the reach of children and exercise caution when operating this product in the presence of children. Water or moisture
may enter the transmitter inside through gaps in the antenna or joystick and cause model instability, even out of control.
If running in the wet weather(such as game) is inevitable, always use plastic bags or waterproof cloth to cover the
transmitter.
This device complies with part 15 of the FCC Rules. Operation is subject to the following two conditions:
This device may not cause harmful interference, and Prevents external wireless interference, including interference that
may cause undesired operation.
Any Changes or modifications not expressly approved by the party responsible for compliance could void the user's
authority to operate the equipment.
WARNING
SAFETY PRECAUTIONS

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CONTENT
Chapter 1 Features of F121................................................................................................................................1
Chapter 2 Before Flight.......................................................................................................................................1
2.1 Power Supply.........................................................................................................................................1
2.2 Remote Controller..................................................................................................................................1
2.3 F121 .....................................................................................................................................................2
2.4 Joysticks & Flight Movements ...............................................................................................................3
Chapter 3 Get Ready to Flight ..........................................................................................................................5
3.1 Motor Installation....................................................................................................................................5
3.2 Propellers Installation ............................................................................................................................5
3.3 Power On F121......................................................................................................................................7
3.4 Flight Note..............................................................................................................................................7
3.5 Setup Compatible Transmitters .............................................................................................................7
3.6 Binding...................................................................................................................................................9
3.7 Arm and Disarm F121............................................................................................................................9
Chapter 4 Flight at Different Flight Modes............................................................................. 错误!未定义书签。
4.1 At Altitude Mode: Rise/Descend ..........................................................................................................11
4.2 At Altitude Mode: Hover .......................................................................................................................11
4.3 At Altitude Mode: Forward/Backward/Right/Left ..................................................................................11
4.4 At Altitude Mode: Clockwise/Anticlockwise Rotation ...........................................................................11
4.5 At Stabilize Mode.................................................................................................................................11
4.6 Low Voltage Alarm...............................................................................................................................11
Chapter 5 Image Transmission of F121............................................................................................................11
Specification ....................................................................................................................................................13

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Chapter 1 Features of F121
As the mini racing drone that can fly at high speed at Altitude Hold Mode, F121 is very easy to master for drone
freshman. The inertial navigation system technology blending Kalman filtering, gyro, accelerometer and
barometer makes F121 possible to flight through narrow space with accuracy and hold altitude even it’s less
than one-meter height to the surface or at high speed. With three flight modes Alt-Hold at low speed, Alt-Hold at
high speed and Stabilize, beginners can flight stably at the first trial.
F121 is monitored by RadioLink mini racing drone flight controller CS360, which is different from other flight
controllers with PID needs to be set before use,will tune automatically. The software noise reduction technology
not only enables a more pleasant flight but also makes the motors more responsive and more efficient than
traditional 8520 coreless motors.It can be thrown and start to fly at any angle even under high-speed and
remains stable even facing with sudden airflow fluctuations such as during takeoff, under braking, or after
extended flying. Without compass locking, F121 always automatically modify angles during flight .
Chapter 2 Before Flight
2.1 Power Supply
Power for transmitter T8S: Make sure the transmitter is fully charged.
Power for F121: The voltage of 1S LiPo battery packed with F121 by default is not fully charged so the battery
needs to be charged with the charger CM120 before flight.
The LiPo battery charger CM120, specially designed for 1S LiPo battery, sharing the professional development
and high precision of CB86PLUS, ensures safer charging and battery life span.
Charging current can be set as 1A or 2Aby toggling the switch at the side of the charger.
Red LED indicates the battery is under charging and green LED indicates the battery is fully charged.
CM120 applies general USB connector, both computer and power bank for mobile phone can be used with
CM120.
Note Voltage output of power supply should be NO higher than 5V.
2.2 Remote Controller
The two joysticks of T8S correspond to the four basic channels respectively . The below example takes
RadioLink radio T8S Mode 2 (Throttle on the left stick) .
Left joystick
Make the F121 rise or descend by toggling the left stick vertically upward or downward and rotate clockwise or
anticlockwise by toggling the left stick to the left or right.
Right joystick
Make the F121 fly forward or backward by toggling the right stick vertically upward or downward and turn left or
right by toggling the right stick to the left or right.

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Note If it’s the transmitter from other brands used with RadioLink F121, make sure that the receiver should be
SBUS signal output supported. Once the receiver is installed on the mini drone, the phase of the throttle should
be reversed while the other three channels normal and the CH5 should be set with a 3-way switch.
2.3 F121
Assembled as building block makes the RC students exercise their DIY ability and free from lengthy mobile
games.Learning knowledge of science and technology when assembling, setting parameters and flight.
2.4 RC Joysticks & Flight Movements
A. Throttle: Upward/ Downward/Hover
Push the Throttle Stick (on the left) vertically upward and F121 will rise while if push the Throttle Stick (on the left)
vertically downward, then the F121 will descend.
If at Alt-Hold Mode, push the Throttle Stick vertically upward till the F121 flight at the preferred height , then toggle the
Throttle stick back the center position and release , the F121 will remain at this height.
Note Hovering is also called Altitude Hold, which can be only realized under the Alt-Hold Mode both either at low
speed or high speed. BUT NOT STABILIZE MODE.
65mm prop(CW)
8520 motor(CCW)
Prop protector
Motor
Protector
65mm prop
(CCW)
8520 motor
(CW)
Prop
protector
Motor
protector
65mm prop(CW)
8520 motor(CCW)
Prop protector
Motor protector
65mm prop(CCW)
8520 motor(CW)
Prop protector
Motor protector
Camera
Camera protector
CS360 flight controller
Fiber
Frame
Cable(receiver& flight controller)
Battery frame
R8SM receiver
PA1.7*8
Screws
F121 cover
* CW: Clockwise
* CCW: Counter Clockwise
ROLL
Make F121
turn left/right
PITCH
Make F121
forward/backward
THROTTLE
Make F121
rise/descend
YAW
Make F121
clockwise/anti
clockwise
MODE 2

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2.4 Joysticks & Flight Movements
A. Throttle: Rise/ Descend/Hover
Toggle the throttle stick (on the left) vertically upward and F121 will rise and vertically downward, then descend.
If at Alt-Hold Mode, toggle the throttle stick vertically upward till the F121 rises to the preferred height, then
toggle back to center position and release, the F121 will remain at this height.
Note Hovering is also called Altitude Hold, which can be only realized under the Alt-Hold Mode either at low
speed or high speed. BUT NOT STABILIZE MODE.
B. Yaw: Clockwise/Anticlockwise
Toggle the rudder stick (on the left) to the left and F121 will turn anticlockwise and to the right, then clockwise.
Rudder stick to the left , F121 rotates anticlockwise
1m
2m
Rise
Descend
Hover

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C. Pitch: Forward/Backward
Toggle the elevator stick (on the right) vertically upward and F121 will flight forward and vertically downward,
then backwards.
D. Roll: Right/Left
Toggle the sileron stick (on the right) to the left and F121 will turn left and to the right, then turn right.
Elevator stick upward, F121 moves forward
Elevator stick downward, F121 moves backward
Rudder stick to the right, F121 rotates clockwise
Aileron stick to left, F121 turns left

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Chapter 3 Get Ready to Flight
3.1 Motor Installation
To make the aircraft fly, motors usually rotate clockwise(CW)/counterclockwise(CCW) with the propellers. The
rotation direction of F121 motors can be identified by the cable colors. That is, red/blue means motor of
clockwise(CW) while black/white means that of counterclockwise(CCW). It is very important to make sure about the
rotation direction as below when installing motors. Otherwise, the drone would fail to take off.
3.2 Propellers Installation
F121 is installed with propellers protector by factory default. To ensure a safety flight, it’s strongly advised to
check if the protector are well installed .
(1) Find the two notches respectively on the motor protector and propeller protector.
Aileron stick to right, F121 turns right

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(2) Put on the propeller protector from the bottom and adjust the position of the notches correspondingly.
(3) Stabilize the frame with left hand and buckle the notch of one side with right hand. Then buckle the notch of
the other side with left hand. A“DA”sound will be heard if the installation is done with success.
Note After the installation of the four propeller protectors, double confirm if they are leaning or slightly shake
F121 to see if they drop. If they are crooked or drop, repeat the above steps to ensure the well installation.
If the default propellers get worn and needs to be replaced after a period of flight, it is important to well
identify the rotation direction of propellers. If installed incorrectly, F121 can’t take off even the throttle is pushed
to max.
In order to identify the propellers rotation, take a propeller and observe there’s a radian at both sides of the
small cylinder in the middle. The higher part (also called windward side) of the right propeller is at the front and
the rotating motor will make propeller rotate counterclockwise(CCW). On the contrary, that is clockwise(CW)
rotation. For the 65mm GEMFAN propellers used on F121, there are two marked with a letter R, meaning they
should be installed on the motors of clockwise.
When the installation is done, make sure the four motors are vertical to the aircraft frame. Adjust them to
vertical positions if necessary, otherwise F121 may not flight successfully.

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3.3 Power On F121
Before powering on F121, fully charge the 1S LiPo battery first. Plug the PH2.0 end of the battery into the F121,
then insert the battery into the battery frame under at the bottom of F121..
(1) Put F121 on a level surface and do not move it when the green LED is flashing. NEVER power on F121 by
putting on hand as it’s not leveled.
(2) Orange propellers indicates the head of F121 by default. make sure they point to the same direction as the
pilot when powering on and be ready to fly, to ensure safety.
(3) The green LED of F121 will begin flashing when powered on. When it’s off, it means F121 finishes
calibration.
Note Head direction is determinate. If F121 is calibrated with the direction different from the default, it will turn
back to the default direction automatically when starts flying, That’s what we called Head Front Forward Point
Without Compass.
3.4 Flight Note
If it’s the first time of flying drone, flight mode of Altitude Mode-Low Speed is strongly advised to set. At the
altitude mode, when toggle the throttle upward till the drone reaches a certain height and release, F121 will
remain at this height. It’s simpler because pilots only need to toggle the other joystick to make the F121 move
forward/backward or turn left/right. If it’s the Stabilize Mode chosen, try to toggle the joysticks slightly to correct
the flight and avoid the drone having sudden moves.
If F121 drops by hitting something, toggle the throttle joystick to the bottom position immediately to stop motor
rotation.
Make sure the signal output of receiver is SBUS to ensure normal operation of F121. For RadioLink
receivers(R8SM/R6DSM) installed on F121, the led indicator is blue/purple when it’s SBUS working mode.
3.5 Setup compatible Transmitters
F121 is compatible with all RadioLink transmitters AT10/AT10II/AT9/AT9S/AT9S Pro/T8FB/T8S and transmitters
of other brands that support SBUS output.
There are two different receivers optional by factory default, R6DSM or R8SM. R6DSM is compatible with
RadioLink AT10/AT10II/AT9/AT9S/AT9S Pro while R8SM is compatible with RadioLink T8FB/T8S.
T8FB/T8S
RadioLink 8-channel transmitter are well set by factory default with the flight modes. To control F121, binding is
the only thing needs to be done.
There are three flight modes for F121 including Altitude Mode- Low Speed, Altitude Mode- High Speed and
Stabilize Mode. It can be changed by pressing the three-way switch on the right of T8FB- SWB or of T8S- CH5
as below
A
*Press forward is to the front side of T8S
Press backward is to the back side of T8S