Three-dimensional extension linkage
The 3D extension linkage 100 can include at least one arm that includes two elements connected by a joint. The linkage can include an actuation mechanism, additional arms and/or each arm can include more than two elements, tie rods and/or cross pieces connecting two or more arms, and any other suitable components. The linkage 100 functions to translate and rotate a body attached to one end of the arm relative to a primary structure attached to a second end of the arm.
1. A system, comprising:
a wing;
a wing flap;
a plurality of arms, each arm comprising:
a proximal element;
a distal element;
a wing mount fixed to the wing;
a first revolute joint connecting the proximal element to the wing mount;
a second revolute joint connecting the proximal element to the distal element; and
a third revolute joint connecting the distal element to the wing flap,
wherein each revolute joint defines a revolute axis, wherein a majority of the revolute joint axes have a zenith angle larger than a respective elevation angle, and
an actuation mechanism coupled to the plurality of arms and configured to transform the wing flap between a retracted configuration and an extended configuration, wherein, between the retracted configuration and the extended configuration, the wing flap traces a three-dimensional spiral path about a spiral axis, the spiral axis extending in a spanwise direction relative to the wing.
2. The system of claim 1 , wherein the three-dimensional spiral path defines:
a spanwise position change of the wing flap along the spiral axis; and
an angle attack change of the wing flap relative to the wing.
3. The system of claim 2 , wherein the wing is forward swept, wherein the spanwise position of the wing flap in the extended configuration is located inboard of the spanwise position of the wing flap in the retracted configuration.
4. The system of claim 2 , wherein a combined rotation of the first, second, and third revolute joints between the retracted and extended configuration matches the angle of attack change of the wing flap.
5. The system of claim 2 , wherein the three-dimensional spiral path defines:
a vertical translation of the wing flap; and
a chordwise translation of the wing flap.
6. The system of claim 2 , wherein the three-dimensional spiral path is helical.
7. The system of claim 1 , wherein the revolute axes of the second and third revolute joints of each arm are askew and cooperatively define a skew angle.
8. The system of claim 7 , wherein the plurality of arms comprises a first arm and a second arm, wherein the skew angle of the second and third revolute joints of the first arm is different from the skew angle of the second and third revolute joints of the second arm.
9. The system of claim 1 , further comprising a tie rod coupled to each of the plurality of arms by a respective spherical joint.
10. The system of claim 9 , wherein:
the actuation mechanism comprises a rotational actuator defining a rotational axis;
the tie rod comprises two segments, wherein each segment is connected to a different arm of the plurality of arms at the respective spherical joint, wherein the two tie rod segments are connected to the rotational actuator by a first and second joint, respectively, wherein the first and second joints are offset from the rotational axis in opposing directions.
11. The system of claim 9 , wherein an effective length of the tie rod defines a distance between the respective spherical joints, wherein the actuation mechanism is configured to change the effective length of the tie rod.
12. The system of claim 1 , wherein the wing flap is over-constrained by the plurality of arms.
13. The system of claim 12 , wherein a collective stiffness of the plurality of arms exceeds a stiffness of the wing flap, wherein the wing flap deforms during transformation between the retracted configuration and extended configuration.
14. The system of claim 1 , wherein the plurality of arms comprises an inboard arm and an outboard arm, wherein in the retracted configuration, the proximal elements of the inboard and outboard arms are angled inboard and outboard, respectively.
15. The system of claim 1 , wherein the second revolute joints of the plurality of arms translate in the same spanwise direction during transformation from the retracted configuration to the extended configuration.
16. The system of claim 1 , wherein the proximal element and distal element of each arm comprise a plurality of parallel load paths.
17. The system of claim 1 , wherein, for a first arm of the plurality of arms, a middle portion of the proximal element overlaps a portion of the distal element in the retracted configuration.
18. The system of claim 1 wherein said plurality of arms resides completely within the wetted outer surface of said wing when in the retracted configuration.