Unmanned flying device

1. An unmanned flying device comprising:

a body;

a first motor;

a top rotor assembly driven by the first motor;

at least first and second blades coupled to the top rotor assembly;

a second motor;

at least a bottom rotor assembly driven by the second motor;

at least third and fourth blades coupled to the bottom rotor assembly;

a central shaft;

wherein the top and bottom rotor assemblies are mounted on the central shaft;

wherein the at least third and fourth blades are coupled to a single rotor bracket that is coupled to the bottom rotor assembly through a respective pitch hinge;

a swashplate connected via linkages to the single rotor bracket to make the pitch of said at least third and fourth blades change in response to an induced angle of the swashplate as it rotates around the central shaft; and

a plurality of servo motors for changing the angle of the swashplate;

wherein when the first and second blades are oriented above the third and fourth blades, (i) the top rotor assembly is positioned above the first motor, (ii) the second motor is positioned above the bottom rotor assembly, (iii) the bottom rotor assembly is positioned above the swashplate, and (iv) the swashplate is positioned above the plurality of servo motors;

wherein controlled flight of the device is achieved by changing the pitch of the single rotor bracket that transmits the motion to the at least third and fourth blades; and

wherein the pitch of the at least first and second blades are not actively controlled.

2. The unmanned flying device as claimed in claim 1 , wherein there are two servo motors for changing the angle of the swashplate.

3. The unmanned flying device as claimed in claim 2 , including a spherical bearing for swashplate pivoting.

4. The unmanned flying device as claimed in claim 1 , including a spherical bearing for swashplate pivoting.

5. The unmanned flying device as claimed in claim 1 , wherein the at least first and second blades are free to flap around a hinge essentially parallel to the plane of rotation in response to centrifugal and aerodynamic forces.

6. The unmanned flying device as claimed in claim 5 , wherein the first and second blades are coupled to a rotor bracket through a respective single hinge essentially parallel to the plane of rotation of the first rotor.

7. The unmanned flying device as claimed in claim 6 , comprising a first arm coupling the first blade to the rotor bracket and comprising a second arm coupling the second blade to the rotor bracket.