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Old Jan 10, 2015, 02:53 AM
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does quadcopter need identical motors?

One of my motors (Multistar MT2213 935kv) is slightly sticky and im planning to replace it. Obviously, idealy i would replace it with an identical motor, but i have spotted an EMAX motor, EMAX MT2213 935Kv. would this be a suitable replacement? or is their compatibility issues between brands?

I live in New Zealand, and can purchase the EMAX motors locally, and can find the Multistars at hobbyking only. Ive had about 30mins total fly time since i got the quad at x-mas so would prefer to buy locally rather than a minimum 2.5 week wait on shipping.
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Old Jan 10, 2015, 03:15 AM
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It depends on if they are truly identical or not. A lot of multistars are just green anodized versions of other brands motors but are direct copies otherwise. For example, I have a quad with two hengli W42-20 880kv motors and two Multistar 4220 880kv motors. The motors are exactly the same besides the fact that the henglis are black and the multistars are green, and therefore that quad flies fine despite me having used two "different" motors.

If the motors perform different, that's when you will have issues.
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Old Jan 10, 2015, 04:31 AM
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Originally Posted by BuffaloJustin View Post
It depends on if they are truly identical or not. A lot of multistars are just green anodized versions of other brands motors but are direct copies otherwise. For example, I have a quad with two hengli W42-20 880kv motors and two Multistar 4220 880kv motors. The motors are exactly the same besides the fact that the henglis are black and the multistars are green, and therefore that quad flies fine despite me having used two "different" motors.

If the motors perform different, that's when you will have issues.
Thanks heaps BuffaloJustin! i did think this was the case, as the two i was looking at have identical product names and just looked "re-branded". Thank you for the reassurance. Once again this forum pays off
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Old Jan 10, 2015, 05:41 AM
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It's an interesting point about the effect of different motors: Does it not depend on how good the flight controller is? The flight controller keeps the copter level by adjusting the speed of the motors, and if one motor is behaving differently from the others (within reason) the flight controller will surely compensate by increasing or decreasing the throttle signal to that corner of the copter.

I'm new to multirotors, so I'm floating this to gain knowledge, not to contradict anyone

With my helis I can change the blade diameter on the tail, and the tail gyro (similar to one channel of a flight controller) will still compensate correctly because it only does what its sensor says is needed. I can even have the blades on the wrong way round, or the rotor going the wrong way, and the gyro can still work.
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Old Jan 10, 2015, 07:39 AM
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Abenn, I believe you are correct, the key part being "to a point". The flight controller will compensate by sending a higher or lower throttle signal if a motor is producing more or less thrust then the mean.

Where this could bite you is when you are pushing the limits of a propulsion system; obviously a motor cannot be asked to give more than 100℅. And I would never do some craziness like put 4 different motors on the four corners of a quad
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Old Jan 10, 2015, 07:44 AM
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On my Tarot hex and quad, I use X and V series Sunnysky motors to help identify the back. The motor size and Kv are the same but the color, shaft size and t-prop mounting holes are different.

On other fun-fly quads, I have mixed motor and prop manufacturers, within reason, and they fly great!
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Old Jan 10, 2015, 02:23 PM
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Quote:
Originally Posted by BuffaloJustin View Post
Abenn, I believe you are correct, the key part being "to a point". The flight controller will compensate by sending a higher or lower throttle signal if a motor is producing more or less thrust then the mean.

Where this could bite you is when you are pushing the limits of a propulsion system; obviously a motor cannot be asked to give more than 100℅. And I would never do some craziness like put 4 different motors on the four corners of a quad
Thanks

At least that means the OP should have no problem replacing his Multistar motor with an Emax one that seems to have the same spec., even if it does turn out to be slightly different in some respect.
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