a four rotor quad copter needs all four engines/props to be functioning to fly - if either a prop or motor fails the air vehicle rolls in the direction of that engine due to the change in the center of lift and it tumbles out of the sky like a rock. one potential solution to this condition would be to cycle the opposite prop to control the roll but with stop/reverse time it takes to go from lift to negative lift makes that a non-starter. another solution would be to kill the rotor opposite the failed motor, lose yaw control, spin like a top, and descend at whatever rate that your weight would cause at about 1/2 the lift the vehicle might need to maintain altitude; this solution is better than crashing upside down but probably would still result in a high rate descent and a very hard landing. this proposed device shifts the CG toward the new center of lift from the three functioning engines and gives these engines some control over pitch, yaw, AND ROLL.
so, how does it work? if an engine failure on a quad occurs, the flight control computer (a human couldn't do this quickly enough) would issue a command to cut the rubber bands at the red radio controlled solenoids of all but the one that would pull the battery away from the dead engine. because of the planform of the battery the design rotates it as it moves if it needs to move in the direction that aligns with it's long side. the resultant CG shift would hopefully be enough to allow the three remaining engines to maintain a level orientation and perhaps limp back to a graceful emergency landing; worst case would be to descend at whatever rate that 3/4 of your lift would allow depending on the air vehicle weight. the drawings currently are for an 11.5"x11.5"x0.5" frame which would move the battery CG approximately 5"; a smaller frame would also work but not move the CG as much. The battery movement results in a significant CG shift in the direction of the new center of lift.
The color codes on the pictures are -
orange - plate and track for movement in one direction
blue - plate and track for movement in a direction 90 deg from the first plate
yellow - components of the rubber band assembly (red actuators)
green - traveling center post and tray with gearing to turn battery if necessary
pink - wire paths to be used as necessary
if you see a basic flaw in this or have any suggestions i really would appreciate your input.