Patent ID: 8869504

Claim:
A turbofan engine ( 20 ) comprising: a fan ( 28 ) having a plurality of blades; a transmission ( 60 ) configured to drive the fan; and three spools; wherein: the fan blades have a peak tip radius R T ; the fan blades have an inboard leading edge radius R H at an inboard boundary of the flowpath; a ratio of R H to R T is less than 0.40; said three spools comprise: a first spool comprising: a first pressure turbine ( 50 ); and a first shaft ( 56 ) coupling the first pressure turbine to the transmission; a second spool comprising; a second pressure turbine ( 48 ); a first compressor ( 42 ); and a second spool shaft ( 54 ) coupling the second pressure turbine to the second spool compressor; a core spool comprising: a third pressure turbine ( 46 ); a second compressor ( 44 ); and a core shaft ( 52 ) coupling the third pressure turbine to second compressor; a combustor ( 45 ) is between the second compressor and the third pressure turbine; a first ( 160 ) of said main bearings engages a static support ( 164 ; 164 ′) and a forward hub ( 236 ) of the second spool; a second ( 162 ) of said main bearings engages the first shaft and the forward hub of the second spool; and the core shaft engages at least two of said main bearings, at least one of which is a thrust bearing.