① Never operate models during adverse weather conditions. Poor visibility can cause disorientation and loss of control of pilots’ model.

② Never use this product in a crowd or illegal areas.

③ Always ensure the trim levers at 0 and battery properly charged before connecting the receiver.

④ Always check all servos and their connections prior to each run.

⑤ Stay at a certain distance from the aircraft during flight to avoid getting hurt by the components of high-speed rotation (e.g. Propellers, brush-less motors)

⑥ After landing off, make sure the aircraft is disarmed and props have stopped moving before getting close to touch the aircraft.

⑦ Always be sure about turning off the receiver/powering off the aircraft before the transmitter.

⑧ Follow the instructions of props installation in case of dropping during flight.

⑨ 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.

⑩ 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.




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.




Before Flight





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 2A by 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.




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.



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.




F121 Introduction



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.








Name: F121(Altitude Hold Micro Racing Drone)

Weight: 47.5g(Drone only)

Drone Size: 121*55mm(with antenna; 41mm without antenna)

Package Size: 170X210x113mm(RTF bag);210x163x67mm(Standalone box)

Transmitter Frequency: 2.4G

Image Transmission Frequency: 5.8G

Material: Carbon Fiber (Frame), Plastic (Cover, Bases for Image transmission/battery, Prop protector)

Motor: 8520 coreless with software to reduce noise

Propeller: GEMFAN props with diameter of 65mm

Transmitter: RadioLink 8-channel handle transmitter T8S

Receiver: RadioLink 8-channel mini receiver R8SM

Flight Controller: RadioLink flight controller CS360

Battery: FULLYMAX 3.7V 660mA 25C LiPo Battery

Charger: USB Charger (1A/2A)

Flight Time: 10 minutes, suitable for Indoor and outdoor

Low Voltage Alarm: Green led flashes quickly when lower than 3.7V

Control Distance: 2KM in the air (Maximum range is tested in an unobstructed area free of interference)




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.







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 aileron stick (on the right) to the left and F121 will turn left and to the right, then turn right.











Get Ready to Flight




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.







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 is well installed.

Find the two notches respectively on the motor protector and propeller protector.


  1. Put on the propeller protector from the bottom and adjust the position of the notches correspondingly.
  2. 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.







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.




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.






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.




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






  • Enter BASIC MENU, select MODEL TYPE and choose MULTIROTOR





  • Return to BASIC MENU, select REVERSE and set CH3 Throttle as REV.




  • Enter ADVANCE MENU, select ATTITUDE and set the CHANNEL as CH5, SW3 as SWC with up position as Alt-Hold Mode (Low Speed), middle position as Alt-Hold Mode (High Speed) and low position as Stabilize Mode.






* For more setting instructions of different RadioLink transmitter, please visit to download the corresponding detailed e-manual.







If it’s the RTF version (whole pack including T8S+F121+bag) purchased, there’s no need to bind because the binding is complete by factory default. However, if it’s only the aircraft F121 is purchased, binding between the transmitter and F121 needs to done first.

By default, F121 is equipped with receiver R8SM, which is compatible with Radiolink transmitter T8FB and T8S.

  • Place the T8FB and F121 close to each other within 50 centimeters.
  • Power on the T8FBand F121.
  • There is a black binding button (ID SET) on the side of R8SM, press it for more than 1 second. When the LED of R8SM starts flashing, meaning binding process has started.
  • The binding is complete when the LED is always on.
  • Make sure F121 is armed (Details in next section). Gently push the throttle of transmitter to see if motors move. If doesn’t, retry binding again.





① F121 currently supports SBUS signal output only, always make sure the LED of R8SM/R6DSM is blue/purple, meaning SBUS signals output. If the LED is red, press the binding button twice in 1 second and release to change it to purple/blue.

② If it’s the transmitter of AT9S Pro/AT9S/AT10/AT10II used, channel quantity needs to be set first in order to be compatible with receiver R6DSM. Long press MODE to enter BASICE MENU, select SYSTEM and modify CH-SELECT as 10CH. Otherwise, F121 won’t be able to be armed.




Arm and Disarm F121




How to Arm



Throttle on left (Mode 2): Toggle the left joystick to the lower right corner and hold this position for 3 seconds till the green LED of F121 is on.





Throttle on right (Mode 1): With right joystick at bottom, toggle the left stick to the right and hold this position for 3 seconds till the green LED of F121 is on.






How to Disarm



When the flight is finished, always make sure F121 is disarmed when get close and try touching it to avoid unexpected harm.

Throttle on left (Mode 2): Toggle the left joystick to the lower left corner and hold this position for 3 seconds till the green LED of F121 is off.




Throttle on right (Mode 1): With right joystick at bottom, toggle the left stick to the left and hold this position for 3 seconds till the green LED of F121 is off.





Flight at Different Flight Modes



It’s strongly advised for beginners to start from Altitude Hold Mode (Low-speed) to Altitude Hold Mode (High-speed) then to Stabilize Mode.

It’s better to keep the direction of F121 head same as pilot in order to easily judge the flight direction. Otherwise, F121 may flight towards pilot and get him/her hurt. If the aircraft head is changed unexpectedly and different from pilot’s direction, pull the throttle stick to the lowest position to land F121.



At Altitude Mode:Rise/Descend



Press the CH5 switch of T8S backward, which makes F121 fly at Altitude Hold Mode (Low-speed). Make sure the orange propellers at front when powering F121 on. Then arm F121 and push the throttle joystick vertically upward higher than center position, then the F121 will rise while if push it vertically downward, then the F121 will descend.




At Altitude Mode:Hover




Push the throttle joystick vertically upward till the F121 rises to a height as wish, then toggle it back to center position and release, the F121 will hover at this height.







At Altitude Mode, F121 is able to fly forward/backwards or towards to right/left by toggling the right stick at the certain height.

For beginners, make sure to push the stick gently because being a racing drone, F121 is very responsive. It’s advised to release the stick as soon as toggle to one direction so that F121 will back to level automatically. Otherwise, F121 will keep flying to the toggled direction with accelerated speed.








When get familiar with the above flights, try flight clockwise/anticlockwise because the yaw practice is more difficult to judge the flight direction. Clearly knowing the direction will quickly help master drone flight. Try imagine sitting on the drone could be a better way to practice.

Toggle the rudder joystick to the left and F121 will flight anticlockwise while if to the right, then the F121 will flight clockwise.




At Stabilize Mode



Press the CH5 switch of T8S backward and it keeps F121 work in Stabilize Mode.

When at Stabilize Mode, F121 will flight faster than when at Altitude Mode. Toggle joysticks as gentle as possible to avoid drastic movements, which may possibly hurt the pilot. Make sure that the battery is fully charged before enjoying the flight.




Low Voltage Alarm



When the green LED on F121 starts flashing during flight, it means the voltage of F121 is lower than 3.7V as this value is default for 1S battery. It’s advised to stop flying to avoid battery over discharging.





Image Transmission of F121



The image transmission device of F121is 5.8G 200mW all-channel camera integrated image transmission. If it’s the image transmission version purchased, the binding between F121 and the FPV screen has been done by factory default. Pilots only need to power both on before flight. If it’s the standalone version of F121, an FPV screen or a goggle with integrated 5.8G image transmission receiver is needed and setup by following its instructions.

The default transmission power is 200MW. Available power among 25MW,100MW and 200MW can be changed by pressing the button on the camera.

Note As device of image transmission includes transmit and receive, the distance could be influenced by the gain of transmit and receive.





Image Transmission LED Indicator



  • RED and BLUE (and YELLOW) always on means normal working status.
  • If RED (and YELLOW) is always on while BLUE is off, meaning it’s at Pit Mode. That is, transmission off. The transmission distance is 1-2m. It’s advised to choose this mode if there are many people switching channels simultaneously at the same space so that channels won’t get mixed.




Power and Channel Frequency



After powering on, wait for 10 seconds to initialize, red and blue (and yellow) always on means normal working status. Long press the channels/power switching button, the channel frequency, the channel team and the transmit power will recycle.





Table of Band/Frequency



























































































Frequency Selection: Long press the channels/power switching button for 5 seconds, the RED led flashes once means entering the frequency selection mode. Then short press the button again, the frequency changes each time the button is pressed once. The blue led flashes 1 time means Frequency 1, 2 times means Frequency 2, 3/4/5/6/7/8 etc.

Band Selection: Long press the channels/power switching button for 5 seconds, the RED led flashes twice means entering the band selection mode. Then short press the button again, the band changes each time the button is pressed once. The blue led flashes 1 time means Band A, 2 times means Band B, C/D/E/F etc.

Power Selection: Long press the channels/power switching button for 5 seconds, the RED led flashes three time means entering the power selection mode. Then short press the button again, the power changes each time the button is pressed once. The blue led flashes 1 time means 25mA, 2 times means 100mW and 3 times means 200mW.

Turn on/off the transmission: When at the normal working status (with red/blue led on), quickly press the button twice and the working mode will change. When the red(yellow) led is on and blue led is off, it means it’s at Pit mode (Low power mode). When red (and yellow)/blue LEDs are on, it means the normal transmission mode.


When all parameters set, long press the channels/power switching button, the red and blue LEDs always on means setting saved, then normal working status. Otherwise, the setup mode remains and all the parameters set above can’t be saved with success.



① When installing the image transmission, make sure the heat radiation is considered. Otherwise, the transmission power will decrease even turn off as the protection of overheating is activated.

② It’s normal that the camera will get heated during usage. DO NOT touch it directly with hands in case of getting burnt.

③ If the transmission antenna is broken or not well welded, the transmission distance will be impacted. Replace the antenna as soon as possible.

④ The detailed instructions of setting FPV screen and goggle, please refer to its corresponding manual.

⑤ If there’s interference during the usage, try switching the camera channel first, then search for a new channel on FPV screen or goggle.















Online Manual Contents

F121 User Manual(in PDF)