Two-motion wing-fold mechanism with independent load path
An aircraft wing folding system folds an outboard wing section relative to an inboard wing section between a deployed position and a stored position in two discrete motions where each motion has an independent load path separate of the loading of the wing experienced by in-flight aerodynamic forces. The wing-fold mechanism of the present invention includes a fold assembly comprising a twist component and a fold component operable to fold the outboard wing section from the deployed position to the stored position that remains substantially unloaded with respect to in-flight aerodynamic forces when the wing is in the deployed or flight configuration.
1. A wing-fold assembly for use in aircraft that provides for relative movement of a first wing section about a second wing section that when in a deployed configuration form a wing having a first axis spanning from a wing tip associated with the first wing section to a wing root associated with the second wing section, the wing-fold assembly comprising:
a first device interposed between and rotationally coupling the first wing section to the second wing section wherein the first device rotates the first wing section at a point of rotation about the first axis of the wing relative to the second wing section; and
a second device operable to pivot the first wing section about a second axis responsive to the first device rotating the first wing section about the first axis, the second axis being substantially perpendicular to the first axis and wherein loading of the first wing section as result of in-flight aerodynamic forces in the deployed configuration is conveyed to the second wing section independent of the first device and independent of the second device by a plurality of spar pins at the point of rotation substantially perpendicular to the first axis.
2. The wing-fold assembly of claim 1 wherein loading of the first wing section as result of in-flight aerodynamic forces is conveyed to the second wing section via the plurality of spar pins orientated substantially orthogonal to the first axis and the second axis.
3. The wing-fold assembly of claim 2 wherein the plurality of spar pins structurally mate the first wing section to the second wing section.
4. The wing-fold assembly of claim 2 wherein prior to rotation of the first wing section about the first axis the plurality of spar pins is disengaged.
5. The wing-fold assembly of claim 2 wherein the first wing section includes a first spar aligned with the first axis and the second wing section includes a second spar aligned with the first axis and when the wing is in the deployed configuration the first spar and the second spar overlap and are structurally mated by the plurality of spar pins.
6. The wing-fold assembly of claim 2 wherein structural loads carried by the plurality of spar pins are independent of structural loads carried by the first device and the second device.
7. A method for repositioning a first wing section with respect to a second wing section that when in a flight configuration form a wing, the wing defining a first axis spanning from a wing tip associated with the first wing section to a wing root associated with the second wing section, the method comprising:
rotating by a first device the first wing section about the first axis with respect to the second wing section by a rotational component; and
responsive to the first device rotating the first wing section, folding by a second device the first wing section about a second axis with respect to the second wing section by a folding component wherein the second axis is substantially perpendicular to the first axis and wherein weight of the first wing section is conveyed to the second wing section independent of loads induced by flight operations and wherein loading of the first wing section as result of in-flight aerodynamic forces is conveyed to the second wing section via a plurality of spar pins and independent of the rotational component and independent of the folding component.
8. The method of claim 7 further comprising disengaging the first wing section from the second wing section.
9. The method of claim 8 wherein disengaging comprises removing the plurality of spar pins prior to rotating the first wing section.
10. The method of claim 7 wherein a subset of the plurality of spar pins is orientated substantially orthogonal to the first axis and the second axis and conveys in-flight aerodynamic forces from the first wing section to the second wing section independent of the rotational component and independent of the folding component.
11. The method of claim 7 wherein the first wing section includes a first spar aligned with the first axis and the second wing section includes a second spar aligned with the first axis and wherein the first spar overlaps the second spar in the flight configuration and are structurally mated by the plurality of spar pins, a subset of the plurality.