Unmanned flying device

1. An unmanned flying device, comprising:

a body;

a first rotor to which is coupled at least a first blade;

at least a second rotor to which is coupled at least a second blade;

wherein the first and second rotors are mounted along a common vertical axis;

a coupling assembly for coupling the first blade and the at least second blade to the body, wherein the coupling assembly applies a force that urges the collapsing of the first blade and the at least second blade towards the body;

wherein both the first blade and the at least second blade are rotatable about the body, and wherein the first blade and the at least second blade are deployable away from the body via rotation of the first and the at least second blades about the body when the rotational and aerodynamic forces associated with the rotating blades exceeds the force that urges the collapsing of the first blade and the at least second blade towards the body, and

wherein controlled flight is achieved by only changing the relative pitch of the at least second blade coupled to the second rotor.

2. The unmanned flying device as claimed in claim 1 , comprising a first motor for causing the rotation of the first blade about the body and at least a second motor for causing the rotation of the at least second blade about the body.

3. The unmanned flying device as claimed in claim 1 , wherein without a sufficient force acting upon the first blade and the at least second blade to deploy the first and the at least second blades away from the body, the force applied by the coupling assembly will cause the first blade and the at least second blade to collapse toward the body.

4. The unmanned flying device as claimed in claim 1 , wherein the coupling assembly comprises a rotor bracket and a rotor arm, wherein the rotor arm couples the first blade to the rotor bracket, and wherein the rotor arm is hingedly coupled to the rotor bracket, wherein the unmanned flying device further comprises:

a first spring positioned at the hinge, and wherein the first spring biases the first blade towards the body to thereby urge the first blade towards the body.

5. The unmanned flying device as claimed in claim 4 , wherein the rotor arm comprises a first rotor arm section having a first end and a second end and a second rotor arm section having a first end and a second end, and wherein the first end of the first rotor arm section is hingedly coupled to the rotor bracket, the first end of the second rotor arm section is hingedly coupled to the second end of the first rotor arm section, and the second end of the second rotor arm section is coupled to a first end of the first blade; wherein the unmanned flying device further comprises:

a second spring positioned at the hinge coupling the first end of the second rotor arm section to the second end of the first rotor arm section, and wherein the second spring also biases the first blade towards the body to thereby urge the first blade towards the body.

6. The unmanned flying device as claimed in claim 5 , wherein the first spring and the second spring are torsion springs.

7. The unmanned flying device as claimed in claim 4 , wherein the coupling assembly comprises:

a second rotor arm that couples the second blade to the rotor bracket;

a lower rotor bracket;

a third rotor arm and a fourth rotor arm coupled to the lower rotor bracket;

a third blade and a fourth blade, wherein the third blade is coupled to the third rotor arm and the fourth blade is coupled to the fourth rotor arm;

an upper rotor assembly comprising the first rotor and the first mentioned rotor bracket, wherein the first rotor arm and the second rotor arm are hingedly coupled to the upper rotor assembly; and

a lower rotor assembly comprising the second rotor and the lower rotor bracket, wherein the third rotor arm and the fourth rotor arm are hingedly coupled to the lower rotor assembly.

8. The unmanned flying device as claimed in claim 7 , comprising:

a second spring positioned at the hinge between the second rotor arm and the first mentioned rotor bracket;

a third spring positioned at the hinge between the third rotor arm and the lower rotor bracket; and

a fourth spring positioned at the hinge between the fourth rotor arm and the lower rotor bracket.

9. The unmanned flying device as claimed in claim 8 , wherein each of the first, second, third and fourth rotor arms comprise:

a first rotor arm section having a first end and a second end and a second rotor arm section having a first end and a second end, wherein the first end of the first rotor arm section is hingedly coupled to its respective rotor bracket; and

the first end of the second rotor arm section is hingedly coupled to the second end of the respective first rotor arm section, and the second end of each second rotor arm section is coupled to a first end of its respective blade; and

a rotor arm section coupling spring positioned at the hinge coupling the first end of the second rotor arm section to the second end of the first rotor arm section, and wherein the rotor arm section coupling spring also biases each respective blade towards the body to thereby urge each respective blade towards the body.

10. The unmanned flying device as claimed in claim 7 , wherein the first rotor arm comprises only one hinged section coupling the first blade to the first mentioned rotor bracket and the second rotor arm comprises only one hinged section coupling the second blade to the first mentioned rotor bracket.

11. The unmanned flying device as claimed in claim 1 , wherein in a collapsed position, the first blade and the at least second blade are positioned at least essentially parallel to the body.

12. An unmanned flying device, comprising:

a body;

a first rotor to which is coupled a first blade;

at least a second rotor to which is coupled at least a second blade;

a coupling assembly for coupling the first blade and the at least second blade to the body, and for urging the first blade and the at least second blade to collapse towards the body;

wherein both the first blade and the at least second blade are rotatable about the body, and wherein the first blade and the at least second blade are deployable away from the body via rotation of the first and the at least second blades about the body when the rotational and aerodynamic forces associated with the rotating blades exceeds the urging force that urges the first blade and the at least second blade towards the body, and

wherein controlled flight is achieved by changing the relative pitch of only the at least second blade.

13. The unmanned flying device as claimed in claim 12 , comprising a first motor for causing the rotation of the first blade about the body and at least a second motor for causing the rotation of the at least second blade about the body.

14. The unmanned flying device as claimed in claim 13 , wherein the first blade and the at least second blades will remain in a deployed position until the force urging the first blade and the at least second blade to collapse towards the body is greater than the force upon the first blade and the at least second blade due to the rotation thereof about the body.

15. The unmanned flying device as claimed in claim 12 , wherein the first and the at least second blades will remain at least essentially parallel to the body until a sufficient rotational force is applied to the first blade and the at least second blade to deploy the first and the at least second blades away from the body.