Airfoil shape for flight at subsonic speeds
AssigneeThe United States of America as represented by the Administrator of the National Aeronautics and Space Administration
InventorRichard T. Whitcomb
Life of this patent
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Abstract
An airfoil having an upper surface shaped to control flow accelerations and pressure distribution over the upper surface and to prevent separation of the boundary layer due to shock wave formulation at high subsonic speeds well above the critical Mach number. A highly cambered trailing edge section improves overall airfoil lifting efficiency.
Claims20
An airfoil having a specific design Mach number in the range of 0.7 to 1.0 comprising:
- an airfoil means, said airfoil means including upper surface means for minimizing acceleration of supersonic and subsonic fluid flow over said upper surface means, said upper surface means including a upper curvature, said upper curvature including an upper point of minimum curvature located on said upper surface means aft of a chordwise point of maximum thickness and forward of a midchord station and said upper curvature increasing continuously forward and rearward from said upper point of minimum curvature;
- whereby, at design Mach number, supersonic flow is maintained over a major portion of said upper surface means at an approximately constant Mach number, supersonic flow decreasing to near-sonic velocity thereafter and then remaining at an approximately constant near-sonic velocity over a smaller portion of said upper surface means.
An airfoil designed to operate at a Mach number greater than the critical Mach number without boundary layer separation due to shock wave formation comprising:
- an airfoil means, said airfoil means having an upper surface means including a first region means extending rearward from a near a leading edge station past a midchord station, said first region means for maintaining a supersonic flow and an approximately constant supersonic velocity over said first region means;
- a second region means extending rearward from said first region means, said second region means for producing a drop in velocity from the supersonic velocity over said first region means to a near-sonic velocity, whereby a weak shock wave is formed over said second region means;
- a third region means extending rearward from said second region means, said third region means for maintaining the near-sonic velocity produced by said second region means at an approximately constant value;
- whereby shock wave energy is not sufficiently strong to cause boundary layer separation.
Dependencies are inferred from the claim text.