Blade/disk dovetail backcut for blade/disk stress reduction (6FA+E, stage2)

A turbine blade comprising an airfoil and a blade dovetail, the blade dovetail being shaped corresponding to a dovetail slot in a turbine disk, the blade dovetail including three tangs as a wide tang, a middle tang, and a narrow tang,

• wherein the blade dovetail includes a dovetail backcut sized and positioned according to blade geometry to maximize a balance between stress reduction on the disk, stress reduction on the blade, a useful life of the turbine blade, and maintaining or improving the aeromechanical behavior of the turbine blade,
• wherein a start point of the dovetail backcut, which defines a length of the dovetail backcut along a dovetail axis, is determined relative to a datum line positioned 1.936 inches from a forward face of the blade dovetail along a centerline of the dovetail axis, and
• wherein the start point of the dovetail backcut is at least 0.923 inches in an aft direction from the datum line for the wide tang and at least 1.654 inches in the aft direction from the datum line for the middle tang.

A turbine rotor including a plurality of turbine blades coupled with a rotor disk, each blade comprising an airfoil and a blade dovetail, and the rotor disk comprising a plurality of dovetail slots shaped corresponding to the blade dovetail, the blade dovetail including three tangs as a wide tang, a middle tang, and a narrow tang,

• wherein at least one of the blade dovetail and the dovetail slot includes a dovetail backcut sized and positioned according to blade and disk geometry to maximize a balance between stress reduction on the rotor disk, stress reduction on the blade, a useful life of the turbine blade, and maintaining or improving the aeromechanical behavior of the turbine blade,
• wherein a start point of the dovetail backcut, which defines a length of the dovetail backcut along a dovetail axis, is determined relative to a datum line positioned 1.936 inches from a forward face of the blade dovetail along a centerline of the dovetail axis, and
• wherein the start point of the dovetail backcut is at least 0.923 inches in an aft direction from the datum line for the wide tang and at least 1.654 inches in the aft direction from the datum line for the middle tang.