Can I fly my quadcopter with one propeller or motor loss?
Usually the answer is No!
For redundancy you will need at least a hexacopter but, the best for motor or prop failsafe operations are the octacopters.
In the YouTube video below you can see what happens if you lose one propeller of your quadcopter.
Thanks for the new quadrocopter failsafe algorithm, the aircraft can recovery after propeller or motor loss.
A specialist team from Fast Company is working since 2013 to develop an algorithm that will provide quadcopters capability to safe land even if one motor is lost.
“During normal flight, a quadcopter can produce three independent torques to control its attitude: ‘roll,’ ‘pitch,’ and ‘yaw,’” says Mark Müller. “If a propeller fails, this is no longer possible–the strategy for our algorithm is to give up the yaw torque, and let the machine spin uncontrolled about this axis. We then use the remaining propellers to tilt this axis of rotation, allowing the machine to move around.”
“The idea of allowing the machine to spin at high speed, and still being able to control its position, had the perfect flavor for us,” Müller says. “It sounded surprising and hard to do, but our intuition said that it should be possible. We first looked at the problem of flying the machine with only two propellers, and only later discovered a solution that uses three propellers. After that, we could also show that it is possible to fly the machines with only one propeller.”
via: Fast Company
You can find more interesting quadcopter flying tips here.