The Brayton cycle is a thermodynamic cycle that describes the workings of the gas turbine engine, basis of the airbreathing jet engine and others. It is named after George Brayton (1830–1892), the American engineer who developed it, although it was originally proposed and patented by Englishman John Barber in 1791. It is also sometimes known as the Joule cycle. The Ericsson cycle is similar but uses external heat and incorporates the use of a regenerator. There are two types of Brayton cycles, open to the atmosphere and using internal combustion chamber or closed and using a heat exchanger.

In 1872, George Brayton applied for a patent for his Ready Motor. The engine used a separate piston compressor and expander. The compressed air was heated by internal fire as it entered the expander cylinder. Brayton produced and sold "Ready Motors" to perform a variety of tasks like water pumping, mill operation, even marine propulsion.

Critics of the day claimed the engines ran smoothly and had an efficiency of about 17%.