Aeronautics and astronautics – Aircraft sustentation – Sustaining airfoils
Patent
1982-09-29
1984-05-15
Frankfort, Charles E.
Aeronautics and astronautics
Aircraft sustentation
Sustaining airfoils
244215, B64C 916
Patent
active
044483759
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
My invention relates to a mechanism for supporting and driving a wing flap. More particularly, it relates to a folding truss type flap support/drive mechanism which is adapted to produce a flap movement closely approaching a rectangular Fowler motion verses deflection angle progression.
2. Background Art
Many different types of mechanisms for supporting, guiding and driving a trailing edge wing flap have been developed for a variety of aircraft. They include (1) a simple hinge, (2) a four-bar upright linkage, (3) a four-bar overhead linkage, (4) variable curvature tracks, (5) circular arc tracks and (6) a folding beam four-bar linkage.
There are one or more obvious deficiencies associated with several of the previously mentioned mechanisms. The simple hinge has a low take-off Fowler motion and requires large fairings with high cruise drag. The four-bar upright linkage has deficiencies similar to the simple hinge but to a lesser degree. The four-bar overhead linkage has high actuation forces. The variable curvature tracks have wear problems with roller carriage. The circular arc tracks have low take-off Fowler motion.
My folding truss mechanism was developed in an effort to minimize the cruise drag associated with flap mechanisms fairings, and at the same time achieve the desirable characteristics of the more effective flap systems now available (e.g. the system used on the Boeing 767 aircraft).
DISCLOSURE OF THE INVENTION
The trailing edge flaps of a high performance aircraft must fulfill two functions. They must provide a high lift to drag ratio take-off configuration and a high lift coefficient landing configuration. A high lift drag ratio for take-off can be accomplished by trailing edge flap positions with high Fowler motion (aft motion, which increases wing projected area), a single converging slot between flap and spoiler trailing edge, and a small flap deflection angle. The high lift coefficient for landing requires high Fowler motion, two relatively narrow converging slots (for double slotted flap) and high flap deflection angles. Theoretically, the best Fowler verses deflection angle progression would be rectangular. This would require two separate mechanisms, one to drive the flap straight aft and another to rotate it. This is not a practical solution. Therefore, a single flap mechanism, that approaches the rectangular progression the closest, is the most desirable.
My folding truss flap support mechanism is a compound four-bar linkage scheme. It is simple in concept and for a single-slotted flap configuration contains the same number of links and joints as the flap mechanism for the Boeing 767 aircraft. All joints are simple pin joints or monoballs, which provide positive structural rigidity and precise positioning control for the mechanism, compared with systems such as curved track roller carriage flap mechanisms. All the links in the support mechanism but one have uni-axial loads, which mean lower structural weight than for mechanisms with links subjected to bending loads.
In basic makeup, my folding truss flap support mechanism comprises a drive link which is pivotally attached at its upper end to an upper frame portion of a wing section forward of the flap, e.g. the main wing body, for fore and aft pivotal movement about a first axis. A second pivot axis is established below and aft of the first pivot axis, by a pivotal connection between the lower end of a support link and a fixed frame portion of the wing structure. The upper end of the support link is pivotally attached to both the upper end of a swing link and the after end of a slave link, to form a third pivot axis. A fourth pivot axis is formed at a forward connection of the flap to the lower end of the drive link. A fifth pivot axis is formed where the lower end of the swing link makes a rearward connection to the flap. The drive link, the portion of the flap which extends between the fourth and fifth axis, the swing link, and wing structure form a first four-bar linkage. The support link, the driv
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Barnard Delbert J.
Frankfort Charles E.
Heberer Eugene O.
The Boeing Company
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