A: It's probably because of the wrong wire connection. Switch the connection of the two arbitrary wires on the motors.

Q3: Why my F450 can't be armed when I use another transmitter?

A: When another transmitter is changed, it should be calibrated in the RadioLink Mission Planner and set with corresponding flight modes.

Q4: Why the signal searching of the GPS doesn't function well (slow and no signal) on my F450?

A: RadioLink F450 is installed with M8N GPS TS100. If the signal searched is not good even after 2-3 minutes the F450 is powered, pilots can flight the aircraft up and try searching signals in the sky. Also, cloudy weather and buildings around may affect the signal searching results.

Q5: Why my F450 can't be armed?

A: There are possible serveral reasons as below:

1) The aircraft crashed, making GPS direction different from that of flight controller compass. So the compass needs to be reconnected to the RadioLink Mission Planner to recalibrate.

2) If  the aircraft can't be armed after it's powered on and done auto checking, please check the led indicator on the flight controller. The flashing yellow led means the flight controller has detected disturbances that stop the aircraft taking off. Like, earth's magnetism influents the compass. To solve it, hold the aircraft up away from the ground or rotate it several circles. When there's music tone from the flight controller and the led turns blue, it means the QAV210 is ready to be armed.

3) To arm the aircraft successfully, please wait until the led on flight controller turns from flashing red and blue in turn to only flashing blue after F450 is powered on and done with auto checking.

Q6: Why my F450 bounces when I try landing it?

A: It's because the pilot pulls the throttle down too fast. Eg. When at the Alt-Hold Mode, if the throttle is toggled down too fast and different from the actual height of the aircraft, F450 will bounce. When landing fast and the flight controller will get involved to monitor if it detects the aircraft is still flying. Thus, the pilot may see the aircraft bouncing. 

Q7: Why are the propellers still rotating and don't stop immediately even my F450 is already landed?

A: The flight controller won't stop outputing commands to cease the motors rotation until it detects the aircraft has successfully landed and the throttle joystick is at the lowest position. Then pilots can disarm the model.

Eg. When the aircraft is landed, pull both joysticks to the outside corners to disarm. If the propellers are still moving, the flight controller will take disarming command as throttle joystick at the bottom and the rudder joystick on the left and the aircraft won't be disarmed successfully. So it's strongly adviced to disarm the aircraft when all the propellers completely stop moving.

Q8: Can I remove the step of arming flight controller by pressing the safety button on it?

A: Yes. Search BRD_SAFETYENABLE  at the right column in Full Parameter List in RadioLink Mission Planner  and set it as 0.

Q9: How to turn off flight controller auto checking in F450 and arm it directly with transmitter?

A: Set the ARMING_CHECK in Full Parameter List  in RadioLink Mission Planner as 0.

Q10:  Why the COM port cannot be identified when connecting the flight controller of F450 to the computer?

A: It's generally because of the firmware or the driver.  If the flight controller can be activated (Red and Blue led flashing quickly in turn first then yellow led flashing slowly), it means the problem comes from the driver or the wire. If  the flight controller fails to activate, then the problem should come from the firmware. So please upgrade the firmware via http://radiolink.com.cn/doce/flightcontrollerfirmware.html