An axial flow transonic turbofan jet engine includes a hub (26) from which radiate a plurality of rotor blades (50). A casing (12) surrounds and shrouds the rotor blades (50). Part-span dampers (56) are located between adjacent rotor blades (50) in an annular pattern to stiffen the elongated rotor blades (50) during operation. The distal tips (54) of the rotor blades (50) are convexed and spin within a rub strip (62) embedded within the casing (12). The rub strip (62) includes an annularly troughed contour (60) to closely conform with the convex tips (54) of the rotor blades (50). The hub (26) may also include an annularly troughed contour (60) formed along the roots (52) of the rotor blades (50). The annularly troughed contours (60) in the hub (26) and in the casing (12) are radially aligned with the part-span dampers (56) to reduce drag between the casing (12) and the hub (26) caused by the part-span dampers (56) at transonic speeds.