Aircraft landing gear
An aircraft landing gear including: a sprung arm mounted to a main pivot and carrying one or more wheels; leaf springs; a transfer arm attached to each of the leaf springs; and a swinging link with a first end which is pivotally coupled to the sprung arm via a first swinging link pivot and a second end which is pivotally coupled to the transfer arm via a second swinging link pivot. The leaf springs are arranged to provide a resilient biasing force via the transfer arm and the swinging link which opposes rotation of the sprung arm about the main pivot. Each leaf spring only absorbs a portion of the landing loads, so load and stress levels in each individual spring are lower. The swinging link enables the leaf springs to be positioned remotely from the sprung arm, in a suitable position to optimize the use of space and distribute loads efficiently into the airframe.
1. An aircraft landing gear comprising:
a sprung arm mounted to a main pivot and carrying one or more wheels or skids;
leaf springs;
a transfer arm attached to each of the leaf springs;
a swinging link with a first end pivotally coupled to the sprung arm via a first swinging link pivot and a second end pivotally coupled to the transfer arm via a second swinging link pivot, wherein the leaf springs are arranged to provide a resilient biasing force via the transfer arm and the swinging link which opposes rotation of the sprung arm about the main pivot; and
a retraction actuator arranged to retract the sprung arm by rotating the sprung arm about the main pivot, wherein the retraction actuator is arranged to apply a retraction force to the sprung arm via the leaf springs and the swinging link which causes the sprung arm to retract by rotating about the main pivot, and wherein the leaf springs and the swinging link are arranged to rotate while the retraction force is applied to the sprung arm.
2. The aircraft landing gear according to claim 1 , further comprising a crank arm coupled to the sprung arm and configured to rotate with the sprung arm about the pivot, wherein the first end of the swinging link is pivotally coupled to the sprung arm via the crank arm.
3. The aircraft landing gear according to claim 2 , wherein the sprung arm and the crank arm together form a bell crank.
4. The aircraft landing gear according to claim 1 , further comprising a stop arranged to be contacted by the transfer arm while the sprung arm has rotated about the pivot to a certain position, thereby preventing further rotation of the sprung arm about the pivot beyond the desired position.
5. The aircraft landing gear according to claim 1 , wherein each leaf spring has a distal end which is pivotally coupled to the transfer arm via a distal pivot.
6. The aircraft landing gear according to claim 5 , wherein the leaf springs are arranged in a leaf spring plane, and the distal pivots are normal to the leaf spring plane.
7. The aircraft landing gear according to claim 1 , wherein the leaf springs comprise three or more leaf springs each pivotally coupled to the transfer arm via a respective distal pivot, wherein the three or more distal pivots are arranged in a straight line.
8. The aircraft landing gear according to claim 1 , wherein the leaf springs are arranged in a leaf spring plane and remain in the leaf spring plane as the leaf springs bend to provide the resilient biasing force.
9. The aircraft landing gear according to claim 1 , wherein a first one of the leaf springs has a different spring strength to a second one of the leaf springs.
10. The aircraft landing gear according to claim 1 , further comprising a damping device coupling the sprung arm to the leaf springs.
11. The aircraft landing gear according to claim 1 , wherein the swinging link comprises a damping device which enables the first and second swinging link pivots to move towards and away from each other with a damped motion.
12. An aircraft landing gear comprising:
a sprung arm mounted to a main pivot and carrying one or more wheels or skids;
leaf springs;
a transfer arm attached to each of the leaf springs, wherein each leaf spring has a distal end which is pivotally coupled to the transfer arm via a distal pivot; and
a swinging link with a first end pivotally coupled to the sprung arm via a first swinging link pivot and a second end pivotally coupled to the transfer arm via a second swinging link pivot,
wherein the leaf springs are arranged to provide a resilient biasing force via the transfer arm and the swinging link which opposes rotation of the sprung arm about the main pivot a leaf spring support, wherein each of the leaf springs has a proximal end which is pivotally coupled to the leaf spring support via a proximal pivot;
leaf spring crank arms each coupled to a respective one of the leaf springs so that the leaf spring crank arm coupled to the leaf spring rotates along with the leaf spring about the proximal pivot;
an actuation arm pivotally coupled to the leaf spring crank arms; and
a retraction actuator arranged to move the actuation arm thereby causing the leaf springs to rotate about respective proximal pivots of the leaf springs, and to cause the sprung arm to retract by rotating about the main pivot.
13. The aircraft landing gear according to claim 12 , further comprising an uplock mechanism arranged to prevent the sprung arm from moving after the sprung arm has been fully retracted by the retraction actuator.
14. The aircraft landing gear according to claim 12 , wherein the leaf springs are arranged in a leaf spring plane, and the proximal pivots are normal to the leaf spring plane.
15. An aircraft landing gear comprising:
a sprung arm mounted to a main pivot and carrying one or more wheels or skids;
leaf springs;
a transfer arm attached to each of the leaf springs;
a swinging link with a first end pivotally coupled to the sprung arm via a first swinging link pivot and a second end pivotally coupled to the transfer arm via a second swinging link pivot, wherein the leaf springs are arranged to provide a resilient biasing force via the transfer arm and the swinging link which opposes rotation of the sprung arm about the main pivot;
wherein the main pivot is the mounting point for the sprung arm to a support, and;
the swinging link comprises a pair of outer links joined by an intermediate link which is pivotally attached to the support and to the pair of outer links.
16. An aircraft landing gear comprising:
a sprung arm mounted to a main pivot and carrying a wheel or skid;
leaf springs;
a transfer arm attached to each of the leaf springs;
a swinging link including a first end pivotally coupled to the sprung arm via a first swinging link pivot and a second end pivotally coupled to the transfer arm via a second swinging link pivot, wherein the leaf springs apply a resilient biasing force opposing rotation of the sprung arm about the main pivot, and
a retraction actuator configured to apply a retraction force which rotates the sprung arm about the main pivot to a retracted position, wherein the retraction force is applied by the retraction actuator to the sprung arm via the leaf springs and the swinging link which rotate in response to the retraction force.