Variable pivot trailing edge flap

#An airplane flap located on the trailing edge of a wing may be translated and rotated to vary wing lift characteristics during various phases of flight. There are various means used to obtain movement of the flap to the desired position. One such method as disclosed in British Pat. No. 558,043 utilizes a four-bar linkage arrangement to move the main flap and a parallel motion device to control an aileron supported at the trailing edge of the flap.

#A two-part or double segment flap is controlled by a four-bar linkage with double links extending from wing support structure to the main flap. A third linkage extends from the wing support structure to an actuating axis point which programs movement of an aft segment of the flap. All the links are pivotally mounted and all converge to a distant point ahead of and below the wing when the flap is nested in the cruise position. The forward bar in the four-bar linkage rotatably is actuated at the upper wing support pivot point to control movement of the flap. The third linkage acts through a bell crank the center pivot point of which is pivotally mounted to the main flap to convert downward movement by the link into rearward movement of a control linkage which programs the relative movement of the aft flap segment with respect to the main flap. As the flap translates into flap take-off position the aft part moves uniformly with the main flap. Upon further travel of the flap into the approach mode the aft flap moves relative to the main flap.

#In a variation the third linkage is independently acted upon to impart rotational movement of the aft flap with respect to the main flap in any position of travel of the flaps.

#FIG. 1 shows a fragmented plan view of an airplane showing the flaps of this invention.

#FIGS. 2, 3 and 4 show fragmented side elevational sectional views of the flaps of this invention in various flight positions. FIG. 2 shows the cruise position; FIG. 3 the take-off position; and FIG. 4 the landing approach position.

#FIG. 5 shows the cruise position and FIG. 6 the landing approach position both in fragmented side elevational sectional view of a different embodiment.

#In a double slotted flap 10, see FIGS. 2, 3 and 4, the flap has leading or main flap 12 and trailing or aft flap 14. A set of three pivotally mounted bars 16, 18, and 20 are aligned to converge at a distant point forward of and below the wing 22 when the flaps are in the cruise position as shown in FIG. 2. The forward bar 16 and the aft bar 18 comprise part of a four-bar linkage to pivotally translate the fore or main flap from cruise, to take-off to landing or approach position and back again as required in operating an aircraft. Fore bar 16 is pivotally mounted at 16a to wing support structure 24 and at 16b to a forwardly extending bracket 26 which in turn is integrally mounted to the main flap 12. Aft bar 18 is pivotally mounted at 18a to wing support structure and at its lower end at 18b to bracket 28 which may extend below the flap as shown or may be within flap contour. This pivotal hinging effects a four-bar linkage with the upper bar the wing support structure, the lower bar the main flap and fore and the aft bar completing the combination. The intermediate bar 20 extends from upper pivot point 20a to an actuation pivot point 20b. This bar connects at the actuation pivot point to leg 30a of bell crank 30 which in turn is pivotally mounted at 32 to the main flap through bracket 34. Linkage 36 extends from pivot point 38 on the leg 30b of the bell crank to pivot point 40 which is at an intermediate point along linkage 42. This linkage and linkage 44 are pivotally mounted at upper ends to the aft part of the leading flap at pivot points 42a and 44a respectively at the lower ends at pivot points 42b and 44b respectively to leading areas of the trailing flap 14 to form a four-bar linkage to move the aft segment of flap with respect to the fore segment of flap. The flaps may be driven with a linkage connected to fore bar 16, but preferably the flap is driven by rotating a shaft located along the axis of pivot point 16a.

#In operation the flaps would be in the nested position for cruise as shown in FIG. 2. When in the nested position bar 16 extends at an acute angle with the horizontal. Thus, movement of the translating linkage first cuases a rapid downward movement of the flap with a wide slot between wing structure and main flap when in the take-off position as shown in FIG. 3. Upon further translation into the landing on approach position, as shown in FIG. 4, the main flap is rotated to narrow the slot between wing structure and main flap and the aft segment of flap is extended to create a slot between flap segments. When the flap is translated out of the cruise position and as it rotates up to about 15.degree. the three pivotally mounted bars 16, 18 and 20 continue to extend to meet at a distant point and the actuation pivot point 20b remains in a constant position with respect to the main flap. Upon further rotation the actuation pivot point moves down with respect to the main flap to program movement of the aft flap by imparting a rearward movement to linkage 36 and extend the flap to the approach position. Upon counterrotation of the flap drive linkage reciprocates back to move the aft flap into the nested position in the main flap. Upon further counterrotation the main flap moves into the nested position with respect to the wing structure.

#In a different embodiment as shown in FIGS. 5 and 6 a double slotted flap with main flap 46 and trailing or aft flap 48 are supported from structure 50. An extension 52 from the main flap acts like a carriage. Extension 54 from aft flap is pivotally mounted to the aft end of the carriage at 56. A set of three bars 58, 60 and 62 control movement of the carriage and flaps. These bars or linkages extend to a point forward and below the wing 64 when in the flaps are in the cruise position as shown in FIG. 5. The bars pivotally attach at the upper end at 58a, 60a and 62a respectively to the support structure 50. Forward bar 58 and aft bar 60 are pivotally attached at the lower end at 58b and 60b respectively to the carriage to complete a four-bar linkage for translating the flaps. The intermediate bar 62 extends down to an actuation pivot point 62b where the bar is connected to bell crank 66. The bell crank is pivotally connected at its apex 66a to the carriage or flap extension 52, and at 66b linkage 68 which in turn is pivotally connected at 70 near aft flap 48 to the flap extension 54. This linkage acting through the actuation pivot point controls relative movement between the fore and aft flap segments. The two flap segments remain nested until the flaps have been rotated about 15.degree. . Flap support structure and flap extension and drive bars are all outside wing and flap contour.