Gurney flap

A gurney flap arrangement comprising:

• an airfoil with a trailing edge and an opening in a surface of the airfoil;
• a gurney flap having a first position in which at least a portion of the gurney flap extends through the opening and projects outwardly from the airfoil surface, and a second position in which the gurney flap does not project from the airfoil surface or projects outwardly from the airfoil surface to a lesser extent;
• and
• a gurney flap actuator for moving the gurney flap between at least the first position and the second position;
• wherein the gurney flap actuator is arranged to move the gurney flap in a direction that extends along an inclined angle with less than 90 degrees between the gurney flap and a part of the airfoil surface extending from the opening toward the trailing edge such that when moving from the second position into the first position a distal edge of the gurney flap moves both outward from the airfoil surface and also in a direction extending along the airfoil surface toward the trailing edge;
• the arrangement further comprising:
• a seal disposed about the opening to seal a gap in the opening between the gurney flap and the airfoil, wherein the seal comprises a seal body made of a resilient material, and the seal body includes a scraper lip in contact with the gurney flap and configured to bear against a side of the gurney flap during transition of the gurney flap between first and second positions.

A method for operating a gurney flap arrangement comprising:

• an airfoil with a trailing edge and an opening in a surface of the airfoil;
• a gurney flap having a first position in which at least a portion of the gurney flap extends through the opening and projects outwardly from the airfoil surface, and a second position in which the gurney flap does not project from the airfoil surface or projects outwardly from the airfoil surface to a lesser extent;
• and a gurney flap actuator;
• the method comprising:
• using the gurney flap actuator to move the gurney flap between at least the first position and the second position;
• and
• wherein the gurney flap actuator moves the gurney flap in a direction that extends along an inclined angle with less than 90 degrees between the gurney flap and a part of the airfoil surface extending from the opening toward the trailing edge, with a sliding inclined movement toward the trailing edge, such that when moving from the second position into the first position a distal edge of the gurney flap moves both outward from the airfoil surface and also in a direction extending along the airfoil surface toward the trailing edge;
• wherein the movement of the gurney flap into the first position places the distal edge of the gurney flap alongside the trailing edge of the airfoil, with a spacing between the distal edge and the trailing edge of the airfoil;
• and
• wherein when the gurney flap is in the first position with the distal edge alongside the trailing edge then the distal edge of the gurney flap is located on or close to a line extending from the trailing edge along a line perpendicular to the airfoil.