Jens William Ægidius Elling (also Aegidus or Aegidius) (26 July 1861 – 27 May 1949) was a Norwegian researcher, inventor and pioneer of gas turbine who is considered to be the father of the gas turbine. He built the first gas turbine that was able to produce more power than needed to run its own components.
Elling was born in and grew up in Oslo, Norway. He studied mechanical engineering at Kristiania Technical College, (now part of Oslo and Akershus University College of Applied Sciences) graduating in 1881. Between 1885-1902, he worked as an engineer and designer at a number of workshops in Sweden and Norway.
His first gas turbine patent was granted in 1884. In 1903 he completed the first turbine that produced excess power; his original machine used both rotary compressors and turbines to produce 11 bhp (8 kW; 11 PS) net. He further developed the concept, and by 1912 he had developed a gas turbine system with separate turbine unit and compressor in series, a combination that is now common. 
One major challenge was to find materials that could withstand the high temperatures developed in the turbine to achieve high output powers. His 1903 turbine could withstand inlet temperatures up to 400° Celsius (752° F). Elling understood that if better materials could be found, the gas turbine would be an ideal power source for airplanes. Many years later, Sir Frank Whittle, building on the early work of Elling, managed to build a practical gas turbine engine for an airplane, the jet engine. Ellings gas turbine prototypes from 1903 and 1912 are exhibited at Norsk Teknisk Museum in Oslo.
Elling also did significant development work in other areas, such as steam engine controls, pumps, compressors, vacuum drying et cetera.
In 1914 Elling produced a book called Billig opvarmning: veiledning i at behandle magasinovner økonomisk og letvint. (English: Cheap Heating: Guidance for the simple and economical treatment of base burners), which was published by Aschehoug. Books written by Elling are now rare, and are mostly found in museums and libraries.
- Ægidius Elling (Store norske leksikon)
- Bakken, Lars E.; Jordal, Kristin; Syverud, Elisabet; Veer, Timot (2004). "Centenary of the First Gas Turbine to Give Net Power Output: A Tribute to Ægidius Elling". Volume 2: Turbo Expo 2004. pp. 83–88. doi:10.1115/GT2004-53211. ISBN 0-7918-4167-7.
- Gas Turbine Engines - The History of Gas Turbine Engines
- Gas Turbine History (TurboMachine.com) Archived June 3, 2010, at the Wayback Machine