Why did they change the name of the gas turbine to the jet engine?
They use both terms. A turbine engine that's being used in an
aircraft is a "jet engine," and a turbine engine that's being used
in a ground-based application is a "gas turbine." Sometimes it's
the same engine--the Lycoming engine used in the CH-47 as a "jet
engine" is also used in the M-1 tank as a "gas turbine."