Abstract: A rotary Stirling-type engine (100) having a heat chamber (105) with a compressing turbine (107) at one end and a valve assembly (108) through which gas enters the heat chamber (105). At the order end is a nozzle housing (109) for gas exit. A shaft (110) extends from the turbine (107) and is mounted in a bearing (111). Another shaft (112) extends from the nozzle housing (109), mounted in bearing (113). A rotor flywheel (114) is also mounted on shaft (110) and fixed in place by socket pin (115). The engine also contains insulating jacket (120), regenerating a housing (122) and a heat sink (126). In the engine, gas is compressed by the turbine (107) until it opens valve (108). The passes through and expands in the heat chamber where it receives heat radiation (eg. Solar) through a glass window (121). The gas cannot escape back through the valve (108) but rather through two circumferentially mounted nozzle adjusters, spinning the whole central assembly, including the compressing turbine (107), as it escapes.