Hinge mechanism for a weight-shifting coaxial helicopter

An unmanned helicopter comprising:

• a propulsion system comprising:
• a first rotor assembly comprising a first motor coupled to a first rotor, the first rotor comprising a plurality of first fixed-pitch blades;
• and
• a second rotor assembly comprising a second motor coupled to a second rotor, the second rotor comprising a plurality of second fixed-pitch blades, the second rotor being coaxial to the first rotor, the second rotor configured to be counter-rotating to the first rotor;
• a fuselage comprising:
• a power source;
• and
• a controller;
• and
• a gimbal assembly coupling the fuselage to the propulsion system, the gimbal assembly comprising:
• a first gimbal motor configured to control pitch of the unmanned helicopter;
• and
• a second gimbal motor configured to control roll of the unmanned helicopter;
• wherein each of the plurality of first and second fixed-pitch blades is coupled to a hub of its respective rotor via a hinge mechanism that is configured to allow each of the fixed-pitch blades to pivot from a first position to a second position, the first position being substantially parallel to the fuselage and the second position being substantially perpendicular to the fuselage.