Pixhawk Quadrotor – Motors Spin but No Thrust During Takeoff

Pixhawk
1

Pixhawk Quadrotor – Motors Spin but No Thrust During Takeoff

Hi everyone,

I’m working on a DIY quadcopter using a Pixhawk 2.4.8 flight controller.

I recently completed the setup and managed to get the motors spinning. However, I’m facing an issue where the drone does not generate enough thrust to lift off, even though all four motors are running.

Hardware

- Flight Controller: Pixhawk 2.4.8

- Firmware: ArduPilot

- Frame: Quad-X

- ESCs: 4 × brushless ESCs

- Motors: 4 × brushless motors

- Battery: 3S LiPo (12.18 V)

- RC: FlySky transmitter/receiver with PPM output

- Ground station: Mission Planner / QGroundControl

Problem

When I perform a motor test through Mission Planner, all four motors run normally.

During arming and throttle increase:

- All four motors start spinning.

- The motors appear to spin in the correct sequence.

- At around 20% throttle, all motors are spinning… But when it goes to full throttle suddenly 2 motor speed is going to decrease and then stops

- However, the drone produces very little/no noticeable thrust and does not lift off.

I have also checked the motors individually, and they appear to work correctly.

Could incorrect ESC-to-Pixhawk output mapping cause the motors to spin but prevent the quadcopter from producing proper thrust?

What I have checked

- Motor test in Mission Planner → motors spin

- All four motors spin when armed

- ESCs appear to respond

- Battery is charged and providing power

- Motor direction has been checked

- Propellers are installed

- No obvious calibration errors are present

I would appreciate some guidance on what I should check next, particularly:

1. Correct motor/ESC output mapping for Quad-X on Pixhawk 2.4.8

2. Whether incorrect motor order can cause this symptom

3. How to verify the ESC calibration/range

4. How to determine whether the issue is caused by motor direction, propeller direction, ESC calibration, or insufficient motor output

Any suggestions or troubleshooting steps would be greatly appreciated.

Thanks!

2

Hi there!
This sounds like a power issue to me.
Can you check the voltage during spinup?
And could you share more details about the motors and escs you use?

Incorrect motor order should not drastically reduce the motor, but rather cause a flip.

3

I agree that checking the supply voltage under load is a good first step, especially because two motors reportedly slow down and then stop as throttle is increased.

I would also separate the motor-test result from the behavior under closed-loop flight control. A successful individual motor test confirms that the output can drive that motor/ESC, but it does not by itself verify that the motor ordering, rotation directions and propeller configuration are correct for the selected Quad-X frame.

Before attempting another takeoff, I would check:

  1. Remove the propellers and verify each motor number individually against the ArduPilot Quad-X motor layout.
  2. Verify the required rotation direction for each motor, then verify that each propeller matches that rotation direction.
  3. Observe battery voltage while increasing motor output. If voltage collapses when the two motors begin slowing, investigate the battery, connectors and power distribution first.
  4. If voltage remains healthy, check whether the affected ESCs are actually receiving increasing commands when their motors slow down.

The last distinction is useful: if the flight controller is commanding those two outputs down, that points toward configuration/control behavior; if the commands remain high while the motors physically slow or stop, the investigation moves downstream toward the ESC/motor/power path.

If possible, please share the ArduPilot .BIN log from one of these tests together with the exact motor, ESC and propeller specifications. That would make it possible to distinguish commanded output from the actual power/thrust problem instead of guessing from motor sound alone.