Hot gas engine concept
Unconventional engines -Thermal engines with external combustion

The hot gas engine is an engine in which chemical energy is released by combustion outside the capsule. The heat transfer system consists of a regenerator, a cooler and a preheater. The movement of the pistons results from the pressure variation of the engine fluid circulating in a closed circuit within the capsule.

Motion can be transmitted to the power shaft in a wide variety of configurations, and figure 3 illustrates the case of swashplate kinematics.