A turbofan engine comprising: a fan driven by a low pressure turbine, and a compressor following said fan and driven by a single stage high pressure turbine preceding said low pressure turbine in counterrotation therewith; said high pressure turbine comprising a row of rotor blades; said high pressure turbine joined to a first rotor and said low pressure turbine joined to a second rotor; said low pressure turbine including a first stage stator nozzle directly following said high pressure turbine, and including a row of vanes (52,80) disposed directly downstream of said high pressure turbine and joined at opposite ends to downstream radially outwardly inclined outer and inner bands (54,56); said low pressure turbine further comprising a row of rotor blades following said first stage stator nozzle; each of said vanes having arcuate camber between leading and trailing edges (64,66) thereof, and an acute outflow angle for imparting swirl in combustion gases channeled between said high pressure turbine and said low pressure turbine; and said trailing edges being axially tilted in an upstream direction from said inner band with oblique lean at said outer band; wherein said outer and inner bands (54,56) extend in an upstream direction from said vanes (52,80) to define an unobstructed and integrated transition duct increasing in radial elevation between said HP blades and said vanes (52,80); the engine further comprising a midframe including a plurality of struts extending through said first stage LP vanes for supporting the aft end of said first rotor, and in turn supporting said rotor blades of said high pressure turbine. a fan driven by a low pressure turbine, and a compressor following said fan and driven by a single stage high pressure turbine preceding said low pressure turbine in counterrotation therewith; said high pressure turbine comprising a row of rotor blades; said high pressure turbine joined to a first rotor and said low pressure turbine joined to a second rotor; said low pressure turbine including a first stage stator nozzle directly following said high pressure turbine, and including a row of vanes (52,80) disposed directly downstream of said high pressure turbine and joined at opposite ends to downstream radially outwardly inclined outer and inner bands (54,56); said low pressure turbine further comprising a row of rotor blades following said first stage stator nozzle; each of said vanes having arcuate camber between leading and trailing edges (64,66) thereof, and an acute outflow angle for imparting swirl in combustion gases channeled between said high pressure turbine and said low pressure turbine; and said trailing edges being axially tilted in an upstream direction from said inner band with oblique lean at said outer band; wherein said outer and inner bands (54,56) extend in an upstream direction from said vanes (52,80) to define an unobstructed and integrated transition duct increasing in radial elevation between said HP blades and said vanes (52,80); the engine further comprising a midframe including a plurality of struts extending through said first stage LP vanes for supporting the aft end of said first rotor, and in turn supporting said rotor blades of said high pressure turbine.