Patent ID: 7461820

Claim:
An aerofoil having a chord length and a depth and which is adjustable between a high profile configuration for subsonic flow and a low profile configuration for supersonic flow, the aerofoil having an initial angle of attack to oncoming airflow of at least about 22 degrees, the aerofoil including a leading edge which generates a subsonic leading edge breakaway flow in the high profile configuration that comes from beneath the leading edge, an upper surface having a leading portion inclined away from the leading edge and a trailing portion rearward of the leading portion, a lower surface, and a trailing edge, wherein in the high profile configuration the depth of the aerofoil is at least about 30% of the chord length of the aerofoil so that the aerofoil is effective to reattach the leading edge breakaway flow and enables the aerofoil to operate with the initial angle of attack of at least about 22 degrees, and at least one opening provided along the leading portion of the upper surface and arranged to discharge a sufficient volume of gas away from the leading edge to reattach the leading edge breakaway flow to the upper surface.