Patent GB-381962-A (GB)
Title: Improvements in and connected with variable section wings for aircraft
IPC: B64C3/50
Filed: 1931-07-15
Abstract: 381,962. Controlling aircraft. DUNCANSON, F., Merecoombs, Gotherington, Gloucestershire. July 15, 1931, No.20330. [Class 4.] Variable camber wings of the type described in Specification 285,577, [Class 4, Aeronautics], have means incorporated in the aileron construction and/or in the aileron operating mechanism which reduce the control forces to be exercised while operating the ailerons. The invention is described with reference to wings embodying the spar construction described in Specification 326,870, [Class 4, Aeronautics]. In one form, Figs. 1 and 2, flaps c are hinged to brackets on a main spar e but when applied to a wing having a subsidiary spar they are hingedly connected to the rear spar. An aileron d of the Frise type is hinged at n to the flap c which is cut away as shown to accommodate the balance portion d<1>. The flaps are operated by screwed spindles h journalled in trunnion bearings carried by brackets j on spar e and engaging in trunnioned nuts f secured to the flap. Spindles h carry sprockets k and are interconnected by chain and cable transmission, as shown, being operated by means of a worm-wheel sector m<1> which is clutched to one portion of the transmission and is in mesh with a hand-operated worm m<3>. The ailerons are similarly operated by threaded spindles p<1> of which the inner trunnion bearings are pivoted substantially coaxially with pivot axes g of the flaps, thus operation of the flaps does not affect the position of the ailerons relative to them. The ailerons are interconnected by chain and cable transmission operated by transverse movements of a control column w. In a modification, Fig. 3, a bent crank q<1> and link r are mounted on a spindle p<2> journalled in a fixed bearing s on the flap c. The crank q<1> is set at an angle so that equal angular displacements in opposite directions from the mean positions of the two cranks on opposite wings result in dissimilar movements of the ailerons operated by them, that which is raised being moved through a greater angle than that which is depressed. In an application to a biplane having upper and lower flaps c<1>, c<2> respectively, Fig. 4, the upper planes only have ailerons d<11> in the flaps. The flaps c<2> comprising bearing sleeves z having pivots y carried by brackets x on the main spar e<1> of the lower plane, are connected to the flaps c<1> by streamlined struts 9. The bearing sleeves are turned by means comprising an arm 1 secured at the inner end of the sleeve and carrying a worm-wheel sector 2 operated by a cross-shaft 3 geared by chain and sprocket 4 with a hand-wheel 5. Cross-shaft 3 has worms 6 at its ends meshing with worm wheels 7 on short vertical shafts having worms 8 in mesh with the sectors 2. The arms 1 together with rearwardly extending arms 10 of the sleeves z revolubly support cross-shafts 11 fitted with arms 12 at the outer ends connected by wires 18 with leading'and trailing portions of ailerons d<11>. At the inner ends shafts 11 have forwardly extending arms 13 pivotally connected at 14 with depending links 15 connected to crank arms 16 of a control column shaft 17, the pivot axis 14 coinciding with the hinge axis of the flaps c<2>. Fig. 8 shows a lower plane b<2> fitted with a flap c<2> and a Frise aileron d<2> mounted on and turning with the cross-shaft 11. When ailerons without, or with only a small, balance portion are fitted means are incorporated in the operating mechanism to reduce the forces necessary for operation comprising mechanism for imparting larger movements to the upwardly moving aileron than to the downwardly moving one. This increased differential movement may be obtained by making the included angle between the lever arms 16 more acute than is shown in Fig. 4. Means may be fitted for increasing the mechanical advantage of the pilot's control in the neighbourhood of the mean position of the ailerons. In one form, Fig. 13, the control column shaft is divided into portions 17, 17a and a toothed gear is interposed between the two parts comprising toothed segments 20, 24 on shafts 17, 17a respectively in mesh with segments 21, 23 on a countershaft 22. The gears are segments of ellipses and in each case a minimum radius is in mesh with a maximum radius. As shaft 17 is turned from the neutral position gradually increasing radii of gears 20, 23 come into mesh with reducing radii of gears 21, 24 thereby reducing the mechanical advantage. In a modification, Fig. 14, the mechanical advantage of the control column is arranged to be greater in the high-speed position of the flaps than in the high-lift position. In this form portions 17, 17a of the control shaft are interconnected bv levers 31, 34 having a pin and slot connection 32, 33. The forward end of shaft 17 is upwardly or downwardly tilted by means of a screwed shaft 28 geared to the flap operating shaft 3 and engaging in a threaded socket in a forward bearing 26 of shaft 17. This movement brings the pin 32 of lever 31 to the top of slot 33 of lever 34 when the flaps are in the high-speed position whereby, as is shown in Fig. 15, a given angular movement of shaft 17 results in a smaller angular movement of shaft 17a. When the flaps are tilted downwardly for high-lift the shaft 17 occupies the position shown in Fig. 16, relative to shaft 17a in which a given angular movement of shaft 17 results in a slightly larger angular movement of shaft 17a. The operating mechanisms above de-' scribed which are associated with the wings are either contained within the contour of the wings or are arranged on the underside thereof, all projecting parts being encased in detachable streamline covers. The gaps between the fixed parts of the wings, the flaps, and the ailerons are provided with flexible cover strips. The invention is stated to be particularly applicable to aeroplanes with slotted wings.