Two or Three Spools?
A question here for those in the know after a debate on another forum. Is Rolls-Royce new UltraFan design considered a two spool or a three spool engine? On their homepage RR describes that the engine uses Advance 3 core design, but as I see it the UltraFan only have two turbine sections and only two concentric axels, with the inner axel driving the LP compressor as well as the fan section through a reduction gearbox, kind of the same way as on Pratt & Whitneys GTF design.
Any thoughts?