Hub assembly with centrifugal and radial bearings
A rotary system including a yoke having an opening forming a bridge for receiving a spoke extending therethrough. A rotor blade couples to the spoke and a pitch horn positioned outside the opening pitches the rotor blade during flight. A bearing assembly attaches the spoke and the pitch horn to the bridge and control blade forces exerted against the hub assembly during flight.
1. A rotary system for a rotary aircraft, comprising:
a rotor mast;
a swashplate rotatably carried by the rotor mast; and
a hub assembly for securing a rotor blade to the rotor mast, the hub assembly having:
a yoke rigidly attached to the rotor mast, the yoke having:
a thickness; and
an opening extending through the thickness, the opening forming a bridge;
a blade grip for securing the rotor blade to the yoke, the grip having:
an upper plate; and
a lower plate;
a pitch horn operably associated with the swashplate for providing pitching movement of the blade during flight, the pitch horn being positioned outside the opening of the yoke, disposed between the upper plate and the lower plate of the grip, and attached to bridge;
a spoke extending through the opening of the yoke and attached to the upper plate and the lower plate of the grip; and
a bearing assembly configured to attach the spoke and a pitching arm to the bridge, the bearing assembly having:
a first bearing configured to attach the spoke to the bridge, the first bearing being a spherical centrifugal bearing having a conical profile; and
a second bearing disposed within the pitch horn and configured to elastically couple the pitch horn to the bridge;
wherein a focal center of the spherical centrifugal bearing is positioned away from the yoke;
wherein the focal center is selectively located as to fall within a cross-section of the second bearing; and
wherein the bearing assembly controls blade forces exerted against the hub assembly during flight.
2. The rotary system of claim 1 , wherein the first bearing and the second bearing are composed of elastomeric material.
3. The rotary system of claim 1 , wherein the first bearing is positioned within the opening of the yoke.
4. The rotary system of claim 1 , wherein the second bearing is a radial shear bearing.
5. The rotary system of claim 1 , the second bearing having:
a hole extending through the second bearing and configured to receive an attachment means extending from the bridge.
6. The rotary system of claim 1 , further comprising:
a lead/lag damper pivotally attached to the yoke and the grip.
7. A rotary system for a rotary aircraft, comprising:
a yoke having an opening forming a bridge:
a spoke extending through the opening of the yoke and rigidly attached to a rotor blade;
a pitch horn positioned outside the opening of the yoke; and
a bearing assembly operably associated with the spoke and the pitch horn, the bearing assembly being configured to attach the spoke and the pitch horn to the bridge, the bearing assembly having:
a first bearing configured to attach the spoke to the bridge, the first bearing being a spherical centrifugal bearing having a conical profile; and
a second bearing disposed within the pitch horn and configured to elastically couple the pitch horn to the bridge;
wherein a focal center of the spherical centrifugal bearing is positioned away from the yoke;
wherein the focal center is selectively located as to fall within a cross-section of the second bearing;
wherein the pitch horn pitches the rotor blade during flight; and
wherein the bearing assembly controls blade forces exerted against a hub assembly during flight.
8. The rotary system of claim 7 , further comprising:
a blade grip for securing the rotor blade to the yoke, the grip having:
an upper plate; and
a lower plate.
9. The rotary system of claim 8 , wherein the spoke and the pitch horn are disposed between and rigidly attach to the upper plate and the lower plate of the blade grip.
10. The rotary system of claim 7 , wherein the first elastomeric bearing is positioned within the opening of the yoke.
11. The rotary system of claim 7 , wherein the second elastomeric bearing is a radial shear bearing.
12. The rotary system of claim 7 , the second bearing having:
a hole extending through the second bearing and configured to receive an attachment means extending from the bridge.
13. The rotary system of claim 8 , further comprising:
a lead/lag damper pivotally attached to the yoke and the grip.
14. The rotary system of claim 7 , wherein the first bearing and the second bearing are composed of elastomeric material.