Why does my MK not fly?


The purpose of this page is to try and solve some of the more common problems some people have with flying their MK's. Unfortunately most problems can be put down to pilot error as the MK system is basically very stable. However notwithstanding pilot error it is sometimes very difficult to see a fault before the MK has crashed. In order to try and establish what the problem may cause we will use a series of pre-crash symptoms to root out the potential cause. It is fair to say that most problems are quite simple and usually easily solved.


Before we delve into establishing what the problem may be we will assume the following:

  • - The MK is a MikroKopter, has the Standard Software loaded and is using the Standard Hardware
    - The frame is configured to a standard frame configuration and has 4 props and motors
    - The batteries are fully charged on the Transmitter (TX) and MK
    - The MK is being operated within the range of the TX
    - Any alterations and testing is carried out at your own risk and you do not put yourself or anyone else at risk
    - The MK is in sound condition and capable of flight
    - The props are all the same size type and the motors are all the same size and type
    - You are flying within the rules and regulations of the CAA and any local bylaws

When NOT to fly if trying to solve any problems

  • - In the rain, heavy fog or at the risk of heavy rain or freezing conditions
    - In winds above Force 4 - 25.6kmh (16mph). Ideally only up to a Force 3
    - Over people or built up areas
    - In poor visibility
    - Out of range of the MK and TX
    - Close to or over water

This list is by no means complete and extensive. It assumes that you will use common sense and know that the MK can be very dangerous when it is out of control. Not only can it cause serious injury or damage to property it can also prove to be very costly.

Taking Off

Props do not rotate

Problem may be caused by one or some of the following:

  • - GAS not set to the correct channel

    • - Assign GAS stick to the correct channel in the MK tool

    - TX not transmitting on correct TX channel

    • -Rescan the TX to find the correct RX channel or change the crystal

    - RX not plugged in or connector reversed

    • - Plug the Flight controller board into RX, or reverse the RX plug

    - MK not switched on or battery not connected

    • - Check switch and battery connections

    - Motors not free to rotate

    • - Motors should offer little resistance and spin freely. The rotation will appear to be a 'lumpy' but this is normal

    - Motors not connected

    • - Connect the motors

Props rotate but MK will not lift off the ground

Problem may be caused by one or some of the following:

  • - Motors not rotating the right way

    • - Swap any 2 connections to the motor to change their direction

    - Correct props on the correct motors

    • - Swap props onto correct motors - Front/Rear CW Left/Right ACW

    - Props loose on the motor shafts

    • - Tighten props on the motor shafts

    - Too much weight

    • - Reduce the payload weight or increase the power of the motors

    - Props too small or pitch too high

    • - Use greater diameter props or reduce the prop pitch

    - GAS channel not set correctly

    • - Check that the GAS channel is on the correct stick

    - Battery power too low

    • - Change battery

MK lifts but immediately flips over

Problem may be caused by one or some of the following:

  • - Flight controller board upside down

    • - Reassemble MK boards so the Flight Controller board has the arrow in the corner on the top

    - Flight Controller board not facing the right way

    • - Reassemble MK boards so the Flight Controller board has the arrow facing forward towards Motor 1

    - Motors in the incorrect positions

    • - Reconnect the BL-Ctrls to the motors Front = 1 Rear = 2 Right = 3 and Left = 4

    - Motor/s rotating the wrong way

    • - Swap any 2 connections to the motor to change their direction

    - Props on the wrong motors

    • - Swap the props over

    - MK trimming set too high

    • - Set the TX trims to zero on the TX and re-trim

    - POTI set to a stick channel

    • - Check the POTI channels and alter if necessary

    - Faulty wiring the motors and or BL-Ctrls

    • - Check wiring visually and with the MK tool. Faults with the BL-Ctrls will show on one of the pages in the centre of the screen. Also the red LED will light on the faulty BL-Ctrl


MK lifts and rotates slowly

Problem may be caused by one or some of the following:

  • - Compass not calibrated

    - YAW trim set too high

    • - Reset YAW to zero and retrim

    - POTI set to operate YAW cannel

    • - Check that POTI channel is not assigned to YAW (gier) channel. If so reassign to POTI to any one of channels 5 to 8

    - Strong magnetic field affecting compass

    • - Check if buzzer is close to the compass, if so relocate on frame arm. Check you are near sources of high magnetic fields, pylons, sub stations or shielded by steel clad buildings

    - Props and motors not rotating the right way

    - Faulty wiring the motors and or BL-Ctrls

    • - Check all wiring and rectify

MK will not stay still

Problem may be caused by one or some of the following :

  • - NICK and ROLL not trimmed

    • - Set trims to zero and retrim

    - Wind too high

    - MK too near to the ground (less then 1 metre)

    • - MK affected by 'Ground Effect' the downdraught of the props against the ground giving unstable lift.

    - Fault with motor or BL-Ctrl

    • - Check motors and BL-Cntrls and rectify or replace

    - Overcompensation by pilot

    - PID settings not compatible with MK design

    - MK frame not substantial enough and flexing

    • - The frame must resist any movement of the motors in relation to one another. Hold the MK on the props and see if the frame can bend or flex. Increase the material size or quality or provide stiffeners. Remember to keep any additional weight to minimum.

    - Flight setting to sensitive for pilot
    - ACC not calibrated or calibrated off level

    • - Use the centre level to ensure that the FC board is set level, then calibrate the ACC (GAS stick to 1-2 o'clock position) While the ACC does not need to be calibrated every flight, it is important to calibrate it in the ambient temperature that the MK will be flown in. Changes in temperature will require the ACC sensor to be re-calibrated.

    - Gyros not calibrated in ambient conditions

    • - Re-calibrate the gyros (GAS stick 10-11 o'clock position) (Please note this is not the thing same as calibrating the output amplification voltages of the gyros on the FC boards 1.0, 1.1 and 1.2 see below)

    - Sunlight on gyros ( This problem is still under discussion and only seems to affect FC-1.3 boards)

    • - Screen the gyros from sunlight. This problem has recently been brought to the forum and as yet, 22.4.09, there appears to be no explanation as to why this happens

    - Gyro output amplification voltages not calibrated (Only applies to Flight control Boards FC-1.0, 1.1, and 1.2)

    • - Gyro amplification output voltages must be set to around 1.5V. This requires the addition of various sized resistors to increase or lower the output voltages see http://www.mikrokopter.com/ucwiki/en/FlightCtrlManual Section 4 - Step 2 Setting Up the Board. Please note FC-1.3 has self adjusting output voltage calibration.

/!\ ToDo: Solutions

Controlling Height

MK continues to ascend

Problem may be caused by one or some of the following:

  • - Height control not activated
    - Sensor connection fault or sensor faulty
    - POTI channel not set in MK tool
    - Swicth not set to correct channel on TX
    - 2 switches or sliders on one POTI channel controlling Height control
    - GAS set too high
    - MK over rising air current (strong fan or heat source)

MK falls slowly

Problem may be caused by one or some of the following:

  • - Batteries running low
    - GAS reduced
    - Ice on props (only if flown in freezing fog)
    - Sudden barometric change (if flown indoors and the door is opened the MK will drop slightly)
    - Loss of TX signal

Moving the MK

MK does not move in correct direction

Problem may be caused by one or some of the following:

  • - Channels not set correctly on TX and MK tool
    - Flight Control Board not facing forward
    - Wind strength too high

MK oscillates to a fro about central axis

Problem may be caused by one or more of the following

  • - PID settings not set to match weight, motor speed and props
    - Payload off balance
    - Over correction with the sticks

MK diffficult to control

Problem may be caused by one or more of the following

  • - Using a setting the is too sensitive
    - Incorrect use of the sticks
    - Wind too high
    - Incorrect ACC calibration
    - Incorrect Gyro calibration
    - Prop pitch too great
    - Motors and props too powerful for MK weight
    - Battery running low
    - MK out of range of TX
    - Props not strong enough

/!\ ToDo: Symptoms and Solutions

Landing the MK

MK bounces on the ground

MK drops from height and cannot recover

MK behaves strangely when trying to land

/!\ ToDo: Please feel free to suggest any other common problems Links