US Patent 7497664 Methods and apparatus for reducing vibrations induced to airfoils

Methods and apparatus for fabricating a rotor blade for a gas turbine engine are provided. The rotor blade includes an airfoil having a first sidewall and a second sidewall, connected at a leading edge and at a trailing edge. The method includes forming the airfoil portion bounded by a root portion at a zero percent radial span and a tip portion at a one hundred percent radial span, the airfoil having a radial span dependent chord length C, a respective maximum thickness T, and a maximum thickness to chord length ratio (Tmax/C ratio), forming the root portion having a first Tmax/C ratio, forming the tip portion having a second Tmax/C ratio, and forming a mid portion extending between a first radial span and a second radial span having a third Tmax/C ratio, the third Tmax/C ratio being less than the first Tmax/C ratio and the second Tmax/C ratio.