An aircraft wing is provided with two flaps normally nested one above the other, each flap being adapted for alteration of angle of incidence relative to the main wing and at least one being supported on travelling mechanism adapted to displace it rearwardly relative to the main wing and to the other flap. In one form, Fig. 6, a split flap 3 is pivotally mounted at 2 below an extension flap 5 which is carried by mechanism comprising a hydraulic or screw jack of which the plunger 6 carries a pivot 7 for a lever 8 rigid with ilap S. To the end of plunger 6 is pivoted one of a pair of toggle links 9, 10 of which the other is pivoted to ilap 5. The centre pivot 11 of the links is connected to a cable 12 passing through a fixed eye 13 in the wing and provided with a stop 12 such that after a certain rearward travel of the flap the cable is held to cause the toggle links to open and move the flap downward. A spring 14 serves to take up slack in the cable in the nested position of the Ilap. Spring means may be used to return the flap to neutral on the return stroke. The control mechanism of lap 3 may be so interconnected with that of flap 5 or may be such that the flap moves slightly downward when flap 5 is operated, in order to give the latter free passage. Plunger 6 may carry cam means serving to depress flap 3 and may be guided in rollers. In a modification, Fig. 8, the Haps are extended by lazytongs linkage having upper pivots 20, lower pivots 21, and intermediate pivots 22 disposed nearer to the lower than to the upper pivots so that rearward movement of the aftermost links is accompanied by downward movement. Various curved paths may be obtained by asymmetrical arrangement of these pivots. Links 23, 23B carry pivot pins 23C, 23D. A flap 24 is pivoted on pin 23C and is formed with a cam slot 24A engaged by pin 23D. A second lap 25 which is adapted to nest below ilap 24 is similarly mounted on links 23E, 23F. Extension of the linkage is by jack means of which the centre line is shown at 26. When fully extended the chord of the first flap is at an angle of 18J deg. to the chord of the wing and that of the second Hap is at 22 deg. to that of the first.
Aircraft Engineering and Aerospace Technology – Emerald Publishing
Published: Apr 1, 1939