초록 ▼

A multi-element rotor blade includes a main element and an active slat movable relative to the main element. The slat rotates and translates relative to the main element from a base position. The base position provides a compromise between minimum coefficient of drag C D and maximum coefficient of

A multi-element rotor blade includes a main element and an active slat movable relative to the main element. The slat rotates and translates relative to the main element from a base position. The base position provides a compromise between minimum coefficient of drag C D and maximum coefficient of lift C Lmax . In the advancing blade, since the airspeed thereof is significantly greater than the retreating blade, the slat is positively rotated from the base position to minimizes drag at low angles of attack. In the retreating blade, since the airspeed thereof is significantly lower than the advancing blade, the slat is negatively rotated and translated to maximize the coefficient of lift C Lmax .

대표청구항 ▼

1. A multi-element rotor blade for an aircraft comprising:a main element rotatable about an axis of rotation to define an azimuth angle, said azimuth angle comprising an advancing angle between 0 and 180 degrees and a retreating angle between 180 and 360 degrees; said main element receives a pitch i

1. A multi-element rotor blade for an aircraft comprising:a main element rotatable about an axis of rotation to define an azimuth angle, said azimuth angle comprising an advancing angle between 0 and 180 degrees and a retreating angle between 180 and 360 degrees; said main element receives a pitch input adjacent a blade root portion; anda slat movable relative to said main element, said slat movable between a first position during said advancing angle and a second position during said retreating angle. 2. The multi-element rotor blade as recited in claim 1, wherein said slat reaches said first position at an azimuth angle of 90 degrees. 3. The multi-element rotor blade as recited in claim 2, wherein said slat reaches said second position at an azimuth angle of 270 degrees. 4. The multi-element rotor blade as recited in claim 1, wherein said slat defines a base position relative said main element, said first position includes a positive rotation relative said base position and said second position comprising a negative rotation relative said base position. 5. The multi-element rotor blade as recited in claim 1, further comprising a controller operable to move said slat relative said main element in accordance with a prescribed motion schedule. 6. The multi-element rotor blade as recited in claim 1, further comprising a controller operable to actively move said slat relative said main element in response to a sensed parameter. 7. The multi-element rotor blade as recited in claim 1, wherein said salt moves independently relative to said main element without relating movement of the slat with pitching of the main element to reduce drag and increase lift of the multi-element airfoil throughout the axis of rotation. 8. A method of controlling a multi-element rotor blade comprising a slat movable relative to a main element, the slat having a base position relative to the main element, said method comprising the steps of:(1) rotating the main element about an axis of rotation to define an azimuth angle, said azimuth angle comprising an advancing angle between 0 and 180 degrees and a retreating angle between 180 and 360 degrees and receiving a pitch input to said main element adjacent a blade root portion; and(2) moving the slat between a first position during the advancing angle and a second position during the retreating angle, said first position comprising positively rotating the slat relative the base position and the second position comprising negatively rotating the slat relative the base position angle. 9. A method as recited in claim 8, wherein said step (2) further comprises:reaching the first position at an azimuth angle of 90 degrees. 10. A method as recited in claim 8, wherein said step (2) further comprises:reaching the second position at an azimuth angle of 270 degrees. 11. A method as recited in claim 8, wherein said step (2) further comprises:controlling the slat relative the main element in accordance with a prescribed motion schedule. 12. A method as recited in claim 11, wherein said step (2) further comprises:modifying said prescribed motion schedule in response to a flight condition. 13. A method as recited in claim 8, wherein said step (2) further comprises:actively controlling the slat relative the main element in response to a sensed parameter. 14. A method as recited in claim 8, wherein said step (1) further comprises:independently moving the main element without relating movement of the slat with pitching of the main element to reduce drag and increase lift of the multi-element airfoil throughout the axis of rotation. 15. A multi-element rotor blade for an aircraft comprising:a main element rotatable about an axis of rotation to define an azimuth angle, said azimuth angle comprising an advancing angle between 0 and 180 degrees and a retreating angle between 180 and 360 degrees; anda slat movable relative to said main element, said slat movable between a first position during said advancing angle and a second position during said retreating angle, said slat movable between said first position and said second position in a sinusoidal pattern having a minimum amplitude defined by said first position and a maximum amplitude defined by said second position. 16. The multi-element rotor blade as recited in claim 15, wherein said slat reaches said first position at an azimuth angle of 90 degrees and said second position at an azimuth angle of 270 degrees. 17. A multi-element rotor blade for an aircraft comprising:a main element rotatable about an axis of rotation to define an azimuth angle, said azimuth angle comprising an advancing angle between 0 and 180 degrees and a retreating angle between 180 and 360 degrees; anda slat movable relative to said main element, said slat movable between a first position during said advancing angle and a second position during said retreating angle, said slat defines a base position relative said main element, said first position includes a positive rotation relative said base position and said second position comprising a negative rotation relative said base position, said positive rotation approximately +5 degrees of rotation from said base position. 18. A multi-element rotor blade for an aircraft comprising:a main element rotatable about an axis of rotation to define an azimuth angle, said azimuth angle comprising an advancing angle between 0 and 180 degrees and a retreating angle between 180 and 360 degrees; anda slat movable relative to said main element, said slat movable between a first position during said advancing angle and a second position during said retreating angle, said slat defines a base position relative said main element, said first position includes a positive rotation relative said base position and said second position comprising a negative rotation relative said base position, said negative rotation approximately −7.5 degrees of rotation from said base position. 19. A multi-element rotor blade for an aircraft comprising:a main element rotatable about an axis of rotation to define an azimuth angle, said azimuth angle comprising an advancing angle between 0 and 180 degrees and a retreating angle between 180 and 360 degrees; anda slat movable relative to said main element, said slat movable between a first position during said advancing angle and a second position during said retreating angle, said slat defines a base position relative said main element, said first position includes a positive rotation relative said base position, and said second position comprising a negative rotation and translation relative said base position. 20. The multi-element rotor blade as recited in claim 19, wherein said translation is defined from said base position along a translation line approximately 45 degrees down and away from said main element. 21. A multi-element rotor blade for an aircraft comprising:a main element rotatable about an axis of rotation to define an azimuth angle, said azimuth angle comprising an advancing angle between 0 and 180 degrees and a retreating angle between 180 and 360 degrees; anda slat movable relative to said main element, said slat movable between a first position during said advancing angle and a second position during said retreating angle, wherein said slat defines a base position relative said main element, said base position locating a slat chord of said slat in a nose down position relative to a main element chord of said main element. 22. The multi-element rotor blade as recited in claim 21, wherein said slat chord in said base position is approximately −20 degrees nose down relative to said main element chord. 23. A multi-element rotor blade for an aircraft comprising:a main element rotatable about an axis of rotation to define an azimuth angle, said azimuth angle comprising an advancing angle between 0 and 180 degrees and a retreating angle between 180 and 360 degrees; anda slat movable relative to said main element, said slat movable between a first position during said advancing angle and a second position during said retreating angle, wherein said first position and said second position are defined by a virtual hinge point location outside a contour of said main element. 24. A multi-element rotor blade for an aircraft comprising:a main element rotatable about an axis of rotation to define an azimuth angle, said azimuth angle comprising an advancing angle between 0 and 180 degrees and a retreating angle between 180 and 360 degrees;a slat movable relative to said main element, said slat movable between a first position during said advancing angle and a second position during said retreating angle; andan elastomeric coupler assembly attached between said slat and said main element. 25. A method of controlling a multi-element rotor blade comprising a slat movable relative to a main element, the slat having a base position relative to the main element, said method comprising the steps of:(1) rotating the main element about an axis of rotation to define an azimuth angle, said azimuth angle comprising an advancing angle between 0 and 180 degrees and a retreating angle between 180 and 360 degrees; and(2) moving the slat between a first position during the advancing angle and a second position during the retreating angle, said first position comprising positively rotating the slat relative the base position and the second position comprising negatively rotating the slat relative the base position. 26. A method of controlling a multi-element rotor blade comprising a slat movable relative to a main element, the slat having a base position relative to the main element, said method comprising the steps of:(1) rotating the main element about an axis of rotation to define an azimuth angle, said azimuth angle comprising an advancing angle between 0 and 180 degrees and a retreating angle between 180 and 360 degrees; and(2) moving the slat between a first position during the advancing angle and a second position during the retreating angle, said first position comprising positively rotating the slat relative the base position and the second position comprising negatively rotating the slat relative the base position and moving the slat between the first position and the second position in a sinusoidal pattern having a minimum amplitude defined by said first position and a maximum amplitude defined by said second position and translating the slat relative the neutral position to reach the second position. 27. A method of controlling a multi-element rotor blade comprising a slat movable relative to a main element, the slat having a base position relative to the main element, said method comprising the steps of:(1) rotating the main element about an axis of rotation to define an azimuth angle, said azimuth angle comprising an advancing angle between 0 and 180 degrees and a retreating angle between 180 and 360 degrees; and(2) moving the slat between a first position during the advancing angle and a second position during the retreating angle in a 2P function with 2 cycles per revolution of the main element about the axis of rotation, said first position comprising positively rotating the slat relative the base position and the second position comprising negatively rotating the slat relative the base position. 28. A method as recited in claim 27, wherein said step (2) further comprises the slat moving to the first position twice during the advancing angle and the slat moving to the second position twice during the retreating angle.