I am now planning to buy a drone kit - A very light weight toy grade types. Know very little on this subject as of now. Before doing that I have a few questions. Can we assume that if there are four motors they can't all be equally strong even if they are from same vendor and same model? If so do receivers detect this inequality and autocorrect? Can this inequality be informed to the receiver by any configuration so that it can deal with it? Is there any receiver capable of doing this? Is it considered ok to add some light weights on the stronger motor ends to help keep the frame stable?

Otherwise do you have any suggestions of what is a good toy grade drone frame kit for 3.7 v coreless motors, with 4.5 cm propellers and a lipo battery.



As you guess, motors are approximately equal but are never balanced exactly enough to fly without active stabilising.

The receiver just sends the model the position of the sticks on the transmitter, it doesn't know anything about flying the drone.

You need a flight controller - a microprocessor with accelerometers that detects the angle and rotation of the drone and calculates the power required for each motor in order to match the commands from the receiver.

The flight controller can easily handle minor manufacturing differences between motors. In fact they can handle completely different motors or propellers by reducing the power to match the least powerful corner. Similarly they can allow for an unbalanced centre of gravity simply by increasing power in one direction. Obviously it's better to keep things balanced, so all motors can operate at full power - particularly on a brushed drone that doesn't have much power to spare.

If you want a small brushed drone, you might as well just get something like this, as it's often cheaper than buying the parts individually: https://uk.banggood.com/Eachine-E010-Mini-2_4G-4CH-6-Axis-Headless-Mode-RC-Drone-Quadcopter-RTF-p-1066972.html

  • $\begingroup$ Understood Robin. Thanks. Planning to make one from a similar kit. Trying to learn. Later will try a bigger drone. For now looking for a kit like banggood.app.link/yvv2N6lfpjb but for a slightly bigger 45 mm propellor. Now the question that follows is how do they ensure motors are equally strong in ready made drones? $\endgroup$
    – Raster R
    Sep 9 at 8:21
  • $\begingroup$ I've added a paragraph about that. Flight controllers are really good at allowing for imbalances. $\endgroup$ Sep 9 at 8:47
  • $\begingroup$ Got that Robin. In case of toy ready made drones how does the manufacturer ensure motors are equally strong? Like the one you shared. It would only have a receiver. No? Is it just a matter of testing the motors and ensuring they have similar output. If building from a drone kit we must then somehow ensure we get same strength motors especially for toy grade drones which have only receivers. No? $\endgroup$
    – Raster R
    Sep 9 at 11:28
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    $\begingroup$ The motor manufacturer makes sure that each motor is very similar to all the others. They can make 1000 and any 4 would be reasonably close in output. The flight control board will take care of any differences. You can't get motors, ESCs, a frame and a battery and make it fly. The flight control board is mandatory. $\endgroup$
    – Kevin
    Sep 9 at 13:25
  • $\begingroup$ Kevin, When you say they make 1000s and any 4 will be alike what are the chances that 4 motors I order from a vendor will be equally strong. Are the chances low or pretty good? $\endgroup$
    – Raster R
    Sep 9 at 20:52

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