
A hot gas engine of the Stirling type is disclosed. The engine has a heater head assembly provided with a plurality of separated regenerators connected in series in the heater tube labyrinth. The regenerators may be cascaded in size and mass to meet predetermined heat exchange design conditions. The temperature of exhaust gases exiting directly from the heater head assembly can be optimized at less than 800.degree.F, but more practically at about 1,000.degree.-1,200.degree.F.











