is self-operating at zero flight speed
is not self-operating at zero^flight speed
requires no air for its operation
produces a jet consisting of plasma
turbo-jet engine
ram-jet engine
propellers
rockets
a propeller system
gas-turbine engine equipped with a propulsive nozzle and diffuse*
chemical rocket regine
steam power plant
petrol engine
diesel engine′
gas turbine plant.
less
more
same
may be less or more depening upon speed