a turbine with a variable inlet guide vane assembly in which the vane airfoils extend between inner and outer buttons , and in which a center of rotation of the airfoil is located aft of an aerodynamic center of pressure of the airfoil . the trailing edge of the airfoil extends into both of the buttons such that no gap is formed between the airfoil trailing edge region and a static part of the turbine during movement of the airfoil from an opened position to a closed position .