A by-pass turbofan gas turbine engine, has a by-pass fan, a generally annular core engine duct, a generally annular by-pass duct situated in a generally coaxial relationship with the core engine duct coupled to the by-pass fan, an upstream axial compressor coupled to the core engine duct, a downstream radial compressor coupled to the upstream compressor, a generally annular recuperator with a cool side inlet coupled to the downstream compressor, a generally annular combustor coupled to a cool side outlet of the recuperator, a radial turbine coupled to the combustor and a warm side inlet of the recuperator coupled to the radial turbine, at least one exhaust nozzle coupled to a warm side outlet of the recuperator that discharges into the by-pass duct and a propelling nozzle coupled to the by-pass duct.