An airfoil for a gas turbine engine comprising: spaced apart pressure and suction walls joined at leading and trailing edges to provide an airfoil, intermediate walls interconnecting the pressure and suction walls to provide cooling passageways, the cooling passageways having interior pressure and suction surfaces respectively provided on the pressure and suction walls; and trip strips provided on at least one of the interior pressure and suction surfaces; wherein the airfoil extends in a radial direction from a platform supported on a root to a tip, the cooling passageways extend in the radial direction; wherein feed cavities (80, 82, 84) are provided in the root and fluidly connected to the cooling passageways, each feed cavity having an inlet discrete from the other feed cavities, the cooling passageways spaced apart from one another in a chord-wise direction that extends between the leading and trailing edges; wherein the feed cavities correspond to leading edge, midbody and trailing edge feed cavities, the leading edge feed cavity having first and second cooling passageways, the midbody feed cavity having third, fourth and fifth cooling passageways, and the trailing edge feed cavity having sixth, seventh and eighth cooling passageways; and wherein the airfoil includes first, second and third span regions extending along a span that extends in the radial direction from 0% span near the platform to 100% span near the tip, the first span region extending 0-20% the span +/-5%, the second span region extending 20-60% the span +/-5%, and the third span region extending 60-100% the span +/-5%, characterised in that the trip strips include a chevron-shaped trip strip that is provided on at least one of the interior pressure and suction surfaces (101, 103), and in that the first, second and third span regions have different average P/E ratios, wherein P is a pitch of the trip strips, and E is a height of the trip strip with respect to a support surface of the trip strip. spaced apart pressure and suction walls joined at leading and trailing edges to provide an airfoil, intermediate walls interconnecting the pressure and suction walls to provide cooling passageways, the cooling passageways having interior pressure and suction surfaces respectively provided on the pressure and suction walls; and trip strips provided on at least one of the interior pressure and suction surfaces; wherein the airfoil extends in a radial direction from a platform supported on a root to a tip, the cooling passageways extend in the radial direction; wherein feed cavities (80, 82, 84) are provided in the root and fluidly connected to the cooling passageways, each feed cavity having an inlet discrete from the other feed cavities, the cooling passageways spaced apart from one another in a chord-wise direction that extends between the leading and trailing edges; wherein the feed cavities correspond to leading edge, midbody and trailing edge feed cavities, the leading edge feed cavity having first and second cooling passageways, the midbody feed cavity having third, fourth and fifth cooling passageways, and the trailing edge feed cavity having sixth, seventh and eighth cooling passageways; and wherein the airfoil includes first, second and third span regions extending along a span that extends in the radial direction from 0% span near the platform to 100% span near the tip, the first span region extending 0-20% the span +/-5%, the second span region extending 20-60% the span +/-5%, and the third span region extending 60-100% the span +/-5%, characterised in that the trip strips include a chevron-shaped trip strip that is provided on at least one of the interior pressure and suction surfaces (101, 103), and in that the first, second and third span regions have different average P/E ratios, wherein P is a pitch of the trip strips, and E is a height of the trip strip with respect to a support surface of the trip strip.