A method of pressurizing a closed-cycle engine includes performing a non-steady state operation in which a working fluid flows to or from a pressurized tank: i) to or from a plurality of sumps defined by respective ones of a plurality of cylinder-piston assemblies of the closed-cycle engine; or ii) to or from one or more air bearings associated with each one of the plurality of the cylinder-piston assemblies; or iii) both and performing, before and/or after performing the non-steady state operation, a steady-state operation in which the working fluid flows through the plurality of sumps and the one or more air bearings along a steady-state loop that is fluidly decoupled from the pressurized tank.

Embodiments are directed to a power system for generating mechanical energy from input electrical energy. The system includes a liquid tank configured to house fluid and communicate with a fluid compressor and an evaporator, a fluid compressor configured to compress the fluid to a higher-pressure state, a fluid pump configured to receive fluid from the condenser and convert kinetic energy from the fluid to mechanical energy, and a suction fan configured to blow air between the evaporator and condenser. The evaporator changes the fluid's state from a liquid to a gas. The condenser changes the fluid's state from a gas to a liquid. The system includes an accumulator tank to hold the fluid from the condenser, a piping network that communicates the fluid between the components, an enclosure that houses the components of the power system, and a power supply that delivers electricity to the fluid compressor and electric components.

Embodiments are directed to a power system for generating mechanical energy from input electrical energy. The system includes a liquid tank configured to house fluid and communicate with a fluid compressor and an evaporator, a fluid compressor configured to compress the fluid to a higher-pressure state, a fluid pump configured to receive fluid from the condenser and convert kinetic energy from the fluid to mechanical energy, and a suction fan configured to blow air between the evaporator and condenser. The evaporator changes the fluid's state from a liquid to a gas. The condenser changes the fluid's state from a gas to a liquid. The system includes an accumulator tank to hold the fluid from the condenser, a piping network that communicates the fluid between the components, an enclosure that houses the components of the power system, and a power supply that delivers electricity to the fluid compressor and electric components.

Aircraft with an emission-free drive and method for emission-free driving of an aircraft. The aircraft includes an aircraft thruster structured and arranged to generate thrust force on the aircraft, an aircraft lift device structured and arranged to generate lift on the aircraft, and a heat engine, which is structured and arranged to convert thermal energy into kinetic energy to drive the aircraft thruster, that includes at least one flat-plate Stirling engine drivable by solar thermal radiation.

Aircraft with an emission-free drive and method for emission-free driving of an aircraft. The aircraft includes an aircraft thruster structured and arranged to generate thrust force on the aircraft, an aircraft lift device structured and arranged to generate lift on the aircraft, and a heat engine, which is structured and arranged to convert thermal energy into kinetic energy to drive the aircraft thruster, that includes at least one flat-plate Stirling engine drivable by solar thermal radiation.

Aircraft with an emission-free drive and method for emission-free driving of an aircraft. The aircraft includes a drive device structured and arranged to generate thrust, a lift device structured and arranged to generate lift, and a heat engine structured and arranged to convert thermal energy into kinetic energy to drive the drive device. The heat engine includes at least one flat-plate Stirling engine drivable by solar thermal radiation.

Aircraft with an emission-free drive and method for emission-free driving of an aircraft. The aircraft includes a drive device structured and arranged to generate thrust, a lift device structured and arranged to generate lift, and a heat engine structured and arranged to convert thermal energy into kinetic energy to drive the drive device. The heat engine includes at least one flat-plate Stirling engine drivable by solar thermal radiation.

Provided is a free-piston Stirling engine that can be easily manufactured by reducing manufacturing processes. A free-piston Stirling refrigerator comprises: a piston capable of reciprocating inside a first cylinder; a first leaf spring for controlling the reciprocating motion of the piston; a connection body for connecting the piston to the movable portion of the first leaf spring; a support arm portion for supporting the fixation portion of the first leaf spring in a state where the positional relation with the first cylinder is fixed; a washer for adjusting the movable mass mp of a piston assembly; and an attachment portion that is disposed on the connection body 13 and to which the washer is attached, and the attachment portion is disposed in such position as to enable the washer to be attached while the piston assembly is assembled, thereby reducing disassembly and reassembly processes and allowing easy manufacturing.

Provided is a free-piston Stirling engine that can be easily manufactured by reducing manufacturing processes. A free-piston Stirling refrigerator comprises: a piston capable of reciprocating inside a first cylinder; a first leaf spring for controlling the reciprocating motion of the piston; a connection body for connecting the piston to the movable portion of the first leaf spring; a support arm portion for supporting the fixation portion of the first leaf spring in a state where the positional relation with the first cylinder is fixed; a washer for adjusting the movable mass mp of a piston assembly; and an attachment portion that is disposed on the connection body 13 and to which the washer is attached, and the attachment portion is disposed in such position as to enable the washer to be attached while the piston assembly is assembled, thereby reducing disassembly and reassembly processes and allowing easy manufacturing.

Methods of laser powering unmanned aerial vehicles (UAV) with heat engines are disclosed. The laser powered heat engines are used in conjunction with devices for absorbing laser optical radiation, turning the laser optical radiation into heat, supplying the heat to a working fluid of the heat engine and harvesting mechanical work from expanding working fluid in the heat engine.