Abstract AUTHOR'S NOTE In the comparatively short space of five years, the turbine power unit has established itself on military types, and its employment is now being extended to civil aircraft. Already the modern gas turbine is available in units of far greater power than are obtainable with orthodox reciprocating engines. After the successful early stage of development of turbine-jet units, the industry is now engaged on a second phase comprising turbines driving air-screws, which give improved...