A post elsewhere started this line of thinking, say a quadcopter loses a prop in flight or a motor jams.
Inititially there maybe a tendency for the imbalanced thrust to cause the drone to tumble.

Assuming so........
I believe these motors can be driven in reverse, I think by reversing any two of the three connections. If it is possible for the ESC to reverse connections 'electronically' ......
Let's number the motors/props 1 to 4 clockwise and imagine that either prop 1 is lost or motor 1 jams and the drone starts to tumble.
If the props CAN NOT be disengaged by driving the motor in reverse would it be feasible, in theory at least, to reverse and or drive forwards motor/prop 3 as needed to
a) stop the tumble, and
b) level the drone in the normal hover flying position i.e. largely horizontal, and maintain that position.
If so could motors/props 2 and 4 be accelerated to give the drone a controllable/controlled descent rate?
I assume it would be possible to shut down the power supply to motor.

YES I realise the drone may well descend in a flat spin but wouldn't that be better than a tumbling crash.

I have NO IDEA if a drone's system can react quickly enough to do this and or 'save' the drone, especially if the incident occurred when the drone was low ...... but .

Theoretically, the drones programming can be able to be configured to reverse the motor spin on blockage but that is risky, say when a pilot takes off and the drone flys into the house, it sees a motor overload or blockage and reverse and cause more damage to the drone or house or person. In normal instances the drone when it encounters an overload or blockage it would shut down the motors to stop further harm, damage etc.

So basically you're saying that two of the diagonal working motors are used to lift the drone and the third working motor tries to keep it leveled by forward/reverse rotation, right? Don't know but the f/r switch delay of the third motor should be very fast in this case.

FloridaNext Posted at 3-15 10:43
So basically you're saying that two of the diagonal working motors are used to lift the drone and the third working motor tries to keep it leveled by forward/reverse rotation, right? Don't know but the f/r switch delay of the third motor should be very fast in this case.

So basically you're saying that two of the diagonal working motors are used to lift the drone and the third working motor tries to keep it leveled by forward/reverse rotation, right?

Correct.

Suren Posted at 3-15 09:42
Theoretically, the drones programming can be able to be configured to reverse the motor spin on blockage but that is risky, say when a pilot takes off and the drone flys into the house, it sees a motor overload or blockage and reverse and cause more damage to the drone or house or person. In normal instances the drone when it encounters an overload or blockage it would shut down the motors to stop further harm, damage etc.

Hmm I hadn't thought of that, I was thinking more of 'out in the open' etc..

Suren Posted at 3-15 09:42
Theoretically, the drones programming can be able to be configured to reverse the motor spin on blockage but that is risky, say when a pilot takes off and the drone flys into the house, it sees a motor overload or blockage and reverse and cause more damage to the drone or house or person. In normal instances the drone when it encounters an overload or blockage it would shut down the motors to stop further harm, damage etc.

Isn't it that a motor overload has a different pattern than a free (lost propeller) rotation? What overload should come from a motor w/o a propeller. It could be measured by the rpm/ampere proportion for example.

Anyway, if we ever come to a conclusion, we should patent this stuff right away. Even for military purposes     $$$$$$$