> If a single engine on a quadcopter loses power, it crashes If one motor fails, the quadcopter could turn off the opposite motor and reverse the direction of

> If a single engine on a quadcopter loses power, it crashes If one motor fails, the quadcopter could turn off the opposite motor and reverse the direction of one of the remaining motors, so that it is left with two opposing motors spinning in opposite direction. The torque of two motors might be enough to keep it flying. Some steering would be possible with the assistance of the third working motor which could spin in either direction as needed.