Advanced airfoils for helicopter rotor application
Patent 4314795 Issued on February 9, 1982. Estimated Expiration Date: 
September 28, 1999. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
September 28, 1999. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent References 2614639 3173490 3343512 3721507 3728045 3822105 Helicopter blade Patent #: 4142837 InventorAssigneeApplicationNo. 06/079706 filed on 09/28/1979US Classes:416/223R, SPECIFIC BLADE STRUCTURE (E.G., SHAPE, MATERIAL, ETC.)244/35R, Sustaining airfoils416/237Angular or offsetExaminersPrimary: Powell, Everette A. Jr.Attorney, Agent or FirmInternational ClassesB64C 27/32 (20060101)B64C 27/46 (20060101) AbstractA family of airfoils for use in rotary wing aircraft, particularly helicopters, is disclosed. The family is characterized by having a maximum c1.sbsb.max at M=0.4 and maximum delay in drag divergence while maintaining zero lift pitching moment levels cm.sbsb.o correctable within the range of -0.01 to +0.01. The present family of airfoils provide high lift at maximum angle of attack when the blade is retreating and maximum delay in drag rise or drag divergence when the blade is advancing. The airfoil section of the family enable a helicopter rotor to counteract, more efficiently, the rolling moment which would otherwise be induced by a rotorcraft's forward flight; this is achieved by the present family of airfoils while maintaining the airfoil sectional pitching moment coefficient at or about zero thereby enabling the blade in which the airfoil sections are incorporated to impose minimum structural loads on the rotorcraft's control system. | |
