Advertisement - Our Stirling engine: Just add heat [General Motors Research Laboratories]

Invented back in 1816, the Stirling Thermal Engine is now becoming practical for modern applications. Current improvements have grown out of a cooperative development program with N.V. Philips' Gloeilampenfabrieken, of the Netherlands. Performance of the latest models is encouraging (40% thermal efficiency, for instance, compared to about 28% for conventional sparkignition engines). An experimental three-kilowatt generator set is being tested for Army field use, where quiet is important. Inaudibility at 300 feet has already been attained. The Research Laboratories and other GM groups are also studying Stirling systems from five to five thousand horsepower, for applications ranging from under the sea to outer space.