Mr. Fred Eisert, Air Force Research Laboratory, chief of fan and compressor experimental branch, explains his branch's mission to Mr. Ian Whittle during a tour of the branch facilities on Wright-Patterson Air Force Base, Ohio, Oct. 31, 2017. Whittle is the son of the late Sir Frank Whittle who is credited for inventing the gas turbine engine effectively launching aircraft propulsion into the jet age. (U.S. Air Force photo / Wesley Farnsworth)