Passive mechanical rotor lock for small unmanned aircraft systems (UAS)

A method of controlling a propeller assembly, comprising:

• controlling the propeller assembly wherein the propeller assembly includes:
• a rotating assembly comprising a propeller, the rotating assembly rotatably connected to a non-rotating member so as to rotate about a rotational axis relative to the non-rotating member;
• one or more pairs of magnets comprising a first magnet mounted to the rotating assembly and a second magnet mounted to the non-rotating member, the second magnet forming an attractive magnetic interaction with the first magnet along an alignment direction;
• and wherein:
• the propeller comprises one or more propeller blades;
• in one of the pairs, the first magnet and the second magnet are positioned directly underneath one of the propeller blades in a stowed configuration;
• one or more distances between the first magnet and the second magnet along the alignment direction are adjusted so that the attractive magnetic interaction induces an alignment of the propeller in the stowed configuration when an angular velocity is reduced below a predetermined value;
• and
• deploying the propeller away from the stowed configuration, comprising outputting a propeller torque from a motor and driving the propeller at the angular velocity greater than the predetermined value so that the propeller torque is greater than a force applied to the rotating assembly by the attractive magnetic interaction;
• wherein:
• the first magnet has a first pole;
• the second magnet has a second pole magnetically attracted to the first pole and facing the first pole along the alignment direction in the stowed configuration, and
• the alignment direction is perpendicular to the rotational axis.

A propeller assembly, comprising:

• a rotating assembly comprising a propeller, the rotating assembly rotatably connected to a non-rotating member so as to rotate about a rotational axis relative to the non-rotating member;
• a first magnet attached to the rotating assembly;
• a second magnet mounted or connected to the non-rotating member;
• and
• a mechanism connected to the rotating assembly and comprising the first magnet, the mechanism configured to:
• move the first magnet away from the second magnet into a first configuration in response to a centrifugal force acting on the mechanism, the centrifugal force generated by the rotating assembly rotating about the rotational axis so that the propeller has an angular velocity greater than a predetermined value,
• position the first magnet closer to the second magnet in a second configuration when the angular velocity is smaller than the predetermined value, wherein:
• an attractive magnetic interaction between the first magnet and the second magnet in the second configuration induces an alignment of the propeller in a stowed configuration when the angular velocity is reduced below the predetermined value,
• the attractive magnetic interaction between the first magnet and the second magnet in the first configuration is less than a propeller torque outputted from a motor driving the propeller at the angular velocity greater than the predetermined value, and
• the mechanism moves the first magnet through an angle of 90 degrees from the second configuration into the first configuration.