# Keep quads flying with 3 motors
**URL:** https://greyarro.ws/t/keep-quads-flying-with-3-motors/4238
**Category:** General Drone Discussion
**Created:** [16 October 2018 14:20 UTC](https://greyarro.ws/t/keep-quads-flying-with-3-motors/4238 "2018-10-16T14:20:54Z")
**Posts on this page:** 9
**Page:** 1
### Author:  [@joe.k](https://greyarro.ws/u/joe.k)
#### Post date: [16 October 2018 14:20 UTC](https://greyarro.ws/t/keep-quads-flying-with-3-motors/4238/1 "2018-10-16T14:20:54Z")
> **[Maintaining Flight When a Quadcopter Motor Fails](https://www.hackster.io/news/maintaining-flight-when-a-quadcopter-motor-fails-71aa91995709?gi=fb4aaeef6bfe)**
>
> If you’re flying on a plane and one of the jet engines suddenly fails, the plane doesn’t just plummet from the sky. The pilot can use the…
Maybe coming with a firmware update ?
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### Author:  [@OzoneVibe](https://greyarro.ws/u/OzoneVibe)
#### Post date: [18 October 2018 01:10 UTC](https://greyarro.ws/t/keep-quads-flying-with-3-motors/4238/2 "2018-10-18T01:10:59Z")
Interesting … but, with a lost prop/motor, I’d be far more interested in its ability to RTH whilst spinning like a top than it just staying where it is (2km away over the sea) when the failure happened until the battery dies. Otherwise this doesn’t really help us much.
And, whilst spinning like a top I doubt the compass would be able to point it in the right direction.
Stationary spinning can be achieved just on gyro and inertial sensors, I’d imagine.
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### Author:  [@joe.k](https://greyarro.ws/u/joe.k)
#### Post date: [18 October 2018 07:14 UTC](https://greyarro.ws/t/keep-quads-flying-with-3-motors/4238/3 "2018-10-18T07:14:27Z")
Not sure if it’s spining or wobbelling . Either way, it doesn’t look controllable for horizontal flight.
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### Author:  [@OzoneVibe](https://greyarro.ws/u/OzoneVibe)
#### Post date: [18 October 2018 07:25 UTC](https://greyarro.ws/t/keep-quads-flying-with-3-motors/4238/4 "2018-10-18T07:25:47Z")
The fact that it has two props spinning one way and only one the other means it has to be spinning. Newton’s Third Law.
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### Author:  [@joe.k](https://greyarro.ws/u/joe.k)
#### Post date: [18 October 2018 07:34 UTC](https://greyarro.ws/t/keep-quads-flying-with-3-motors/4238/5 "2018-10-18T07:34:10Z")
I figured they maybe applying bursts of power on the single prop at the same time reducing the power on the other 2 to compensate . My thought was that the motor that has to work harder or the ECU powering it’ would burn out sooner than later. I don’t know.
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### Author:  [@OzoneVibe](https://greyarro.ws/u/OzoneVibe)
#### Post date: [18 October 2018 08:03 UTC](https://greyarro.ws/t/keep-quads-flying-with-3-motors/4238/6 "2018-10-18T08:03:21Z")
If just two motors/props were still running that were opposite one another, and the CoG was in the sweet spot, just those two would enable it to fly - but since they spin in the same direction the quad would spin really fast. (And since the CoG won’t be in the perfect position - it won’t be stable, either,)
If you span the third fast enough to counter the spin, it would also tip over, since there isn’t anything to stop it rotating about the axis of the arms of the two props/motors that are spinning the same way as each other,
Therefore, the drone has to be spinning - and that single prop is lifting that side up, and then being got around to the other side to push that side up, and similarly at all points in between. Basically it’s doing a very fast “toilet bowl” motion to keep everything in balance.
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### Author:  [@OzoneVibe](https://greyarro.ws/u/OzoneVibe)
#### Post date: [18 October 2018 08:09 UTC](https://greyarro.ws/t/keep-quads-flying-with-3-motors/4238/7 "2018-10-18T08:09:13Z")
Actually, if you use the YouTube replay speed controls to slow it down, it’s easy to see that this is exactly what it’s doing.
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### Author:  [@joe.k](https://greyarro.ws/u/joe.k)
#### Post date: [18 October 2018 08:29 UTC](https://greyarro.ws/t/keep-quads-flying-with-3-motors/4238/8 "2018-10-18T08:29:46Z")
So … as you said, lost over water , which would have been the case of a prop failure.
But could be helpful over land.
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### Author:  [@OzoneVibe](https://greyarro.ws/u/OzoneVibe)
#### Post date: [18 October 2018 08:39 UTC](https://greyarro.ws/t/keep-quads-flying-with-3-motors/4238/9 "2018-10-18T08:39:05Z")
Will be interesting to see if they can develop some degree of RTH function with it too.
However, as much as I love fairground rides, I’d hope they have something better developed for passenger carrying drones. 😉