Separable blade attachment for a bearingless rotor of a helicopter
View Patent ↗The invention relates to a separable blade attachment ( 1 ) for a bearingless main rotor of a helicopter with an airfoil blade ( 2 ), a flexbeam ( 3 ) and a control cuff ( 4 ) enclosing at least a predominant portion of said flexbeam ( 3 ). A separable junction arrangement between said flexbeam head ( 13 ), said control cuff ( 4, 22 ) and said root end of said airfoil blade ( 2 ) is mechanical with removable fasteners. A stiffened link ( 17 ) is provided between respective trailing edges ( 9 ) of the control cuff ( 4 ) and said airfoil blade ( 2 ).
1. A separable blade attachment for a bearingless rotor of a helicopter, comprising:
an airfoil blade with a tip end and a root end forming opposite ends thereof;
a flexbeam with an attachment end, the flexbeam being flexible;
a torsion stiff and lead lag stiff control cuff enclosing at least a predominant portion of the flexbeam;
a separable junction arrangement between the attachment end of the flexbeam, the control cuff and the root end of the airfoil blade, wherein the junction arrangement is mechanical between the attachment end of the flexbeam, the control cuff, and the root end of the airfoil blade, with removable fasteners respectively removably connecting the root end of the airfoil blade and the control cuff with the attachment end of the flexbeam, the removable fasteners comprising at least one bolt and wherein a stiffened link is provided between respective trailing edges of the control cuff and the airfoil blade, the stiffened link being mounted to the respective trailing edges of the control cuff and the airfoil blade by the removable fasteners and the stiffened link being push-pull stiff with regard to loads aligned with the trailing edge.
2. The separable blade attachment according to claim 1 , wherein the removable fasteners comprise two bolts.
3. The separable blade attachment according to claim 1 , wherein the stiffened link is aerodynamically adapted to the respective trailing edges of the control cuff and the airfoil blade.
4. The separable blade attachment according to claim 1 , wherein a fairing is provided, the fairing being adapted to be mounted aerodynamically smooth along the leading edge from a profile edge of the control cuff till an airfoil edge of the airfoil blade, the fairing being adapted for clipping to the root end of the airfoil blade and the attachment end along the profile edge of the control cuff and the airfoil edge of the airfoil blade, and the fairing being aerodynamically fitted to the stiffened link.
5. The separable blade attachment according to claim 1 , wherein the at least one bolt together with any fasteners are integrated aerodynamically into the junction arrangement.
6. The separable blade attachment according to claim 1 , wherein the attachment end of the flexbeam is fork shaped to accommodate the root end of the airfoil blade.
7. The separable blade attachment according to claim 1 , wherein the control cuff is mechanically connected to the flexbeam.
8. The separable blade attachment according to claim 1 , wherein the attachment end of the flexbeam is configured for reception of the at least one bolt for connecting the attachment end of the flexbeam to the root end of the airfoil blade, and the control cuff is configured for reception of the at least one of the fasteners for connecting the stiffened link to the respective trailing edges of the control cuff and the root end of the airfoil blade is configured for reception of at least another one of the fasteners for connecting the stiffened link to the trailing edge of the root end of the airfoil blade.
9. The separable blade attachment according to claim 1 , wherein the root end of the airfoil blade is fork shaped, the attachment end of the flexbeam has a flat stepped cross section and the root end of the airfoil blade is arranged in between the control cuff and the attachment end of the flexbeam.
10. The separable blade attachment according to claim 1 , wherein the control cuff is formed with a leading slit and a trailing slit adjacent to the attachment end of the flexbeam.
11. The separable blade attachment according to claim 1 , wherein the control cuff is mechanically connected to the flexbeam by at least one of adhesive, rivets, or screws.