A lock device can be shifted between a locked state and an unlocked state. The lock device includes a lock pin, a solenoid, and a pressing unit. The lock pin is movable between a locked position where a propeller is locked and an unlocked position where the propeller is not locked. The pressing unit presses the lock pin to the locked position by a mechanical pressing force. The solenoid includes a solenoid coil and a plunger. When the solenoid coil is energized, the plunger moves the lock pin to the unlocked position against the mechanical pressing force.

An aircraft propulsion system including at least first airmover, an electric motor configured to at least partially power the at least first airmover, wherein the first airmover includes a propeller having at least a first position configured to provide thrust to the aircraft and a second position configured to recharge a power source, wherein the second position is a reverse windmilling position, and a heat engine configured to at least partially power the first air mover or a second air mover.

Embodiments provide a propeller ground stop mechanism configured to keep an unpowered propeller of an aircraft (e.g. when the aircraft is on the ground and not operating) static. The propeller is prevented from rotating due to external forces (e.g. an air flow caused by wind, manual rotation of the propeller). When the propeller is powered, and the propeller is providing thrust, the propeller ground stop mechanism automatically disengages and does not provide any drag. Among various benefits, the propeller ground stop mechanism provides added safety to the ground support personnel.

A system for propulsor synchronization using electronic brakes is disclosed. The system includes a controller located in an aircraft configured to receive a first signal from a first propulsor sensor of a plurality of propulsor sensors, the first propulsor sensor configured to measure a first motion parameter of a first propulsor of a plurality of propulsors. The controller may receive a second signal from a second propulsor sensor of the plurality of propulsor sensors, the second propulsor sensor configured to measure a second motion parameter of a second propulsor of the plurality of propulsors. The controller may synchronously decelerate the first propulsor and the second propulsor based on the first motion parameter and the second motion parameter.