A hot air engine was based on a device by which English engineer and aeronautical legend?
Hot air engine: A hot air engine (historically called an air engine or caloric engine) is any heat engine that uses the expansion and contraction of air under the influence of a temperature change to convert thermal energy into mechanical work. Hot air engine:  These engines may be based on a number of thermodynamic cycles encompassing both open cycle devices such as those of Sir George Cayley and John Ericsson and the closed cycle engine of Robert Stirling. George Cayley: Sir George Cayley, 6th Baronet (27 December 1773 – 15 December 1857) was a prolific English engineer and is one of the most important people in the history of aeronautics. George Cayley:  Many consider him to be the first true scientific aerial investigator and the first person to understand the underlying principles and forces of flight.
George Cayley