A turbine blade comprising: an attachment root having: an inner diameter end; a first axial end; a second axial end, a rearward direction defined from the first axial end to the second axial end; a first lateral side; and a second lateral side, an end-to-end centerplane between and extending parallel to the first and second lateral sides; an airfoil having: a pressure side; a suction side; a leading edge; and a trailing edge; and a cooling passageway system comprising: a plurality of trunks (100,102,104,106) extending from respective inlets (110,112,114,116) along the root inner diameter end from a leading trunk: near the first axial end to a trailing trunk near the second axial end; and a plurality of outlets along the airfoil including trailing edge outlets fed by the trailing trunk, characterised in that, viewed normal to the end-to-end centerplane: the trailing trunk has a turn passing forward and then rearward; an outside of the turn protrudes forward; the outside of the turn forms a first bump (230,930); the inside of the turn forms a second bump (240,932); and a forward extreme of the second bump is radially outboard of a forward extreme of the first bump. an attachment root having: an inner diameter end; a first axial end; a second axial end, a rearward direction defined from the first axial end to the second axial end; a first lateral side; and a second lateral side, an end-to-end centerplane between and extending parallel to the first and second lateral sides; an inner diameter end; a first axial end; a second axial end, a rearward direction defined from the first axial end to the second axial end; a first lateral side; and a second lateral side, an end-to-end centerplane between and extending parallel to the first and second lateral sides; an airfoil having: a pressure side; a suction side; a leading edge; and a trailing edge; and a pressure side; a suction side; a leading edge; and a trailing edge; and a cooling passageway system comprising: a plurality of trunks (100,102,104,106) extending from respective inlets (110,112,114,116) along the root inner diameter end from a leading trunk: near the first axial end to a trailing trunk near the second axial end; and a plurality of outlets along the airfoil including trailing edge outlets fed by the trailing trunk, a plurality of trunks (100,102,104,106) extending from respective inlets (110,112,114,116) along the root inner diameter end from a leading trunk: near the first axial end to a trailing trunk near the second axial end; and a plurality of outlets along the airfoil including trailing edge outlets fed by the trailing trunk, characterised in that, viewed normal to the end-to-end centerplane: the trailing trunk has a turn passing forward and then rearward; an outside of the turn protrudes forward; the outside of the turn forms a first bump (230,930); the inside of the turn forms a second bump (240,932); and a forward extreme of the second bump is radially outboard of a forward extreme of the first bump. the trailing trunk has a turn passing forward and then rearward; an outside of the turn protrudes forward; the outside of the turn forms a first bump (230,930); the inside of the turn forms a second bump (240,932); and a forward extreme of the second bump is radially outboard of a forward extreme of the first bump.