Patent GB-467969-A (GB)
Title: Improvements in or relating to manual elevation control mechanism for aircraft
IPC: B64C13/42
Filed: 1935-11-18
Abstract: 467,969. Controlling aircraft. HEINKEL, E. Nov. 18, 1935, Nos. 31961 and 31963. Convention dates, Nov. 17, 1934 and Aug. 21, 1935. [Class 4] In elevator control mechanism for aircraft, initially stressed resilient devices are interposed in the transmission mechanism between the hand control member and the elevator in order to prevent excessive stresses being imposed on the wings due to excessive elevator deflection at high speeds. The resilient devices may be associated with fluid damping means and the degree of damping may be adjustable for instance automatically in relation to air speed. The initially stressed resilient devices may be interposed between the hand wheel and control column, in the linkage, or at a link pivot, Fig. 3. Where damping means are associated with the resilient device the degree of damping may be made automatically dependent on air speed, or may be non-automatically variable on the ground or under control of the pilot. One form of resilient device, Fig. 4, comprises a cylinder 2 connected by a rod 3 to the elevator and a piston 4 of which the rod 5 is connected to the control column and carries a yoke 6 having lugs 6a, 6c registering between similar lugs 7a, 7c formed on cylinder 2 and cylinder end cover 2a, respectively. A spring 9 is arranged between lugs 6a and 7a. Cylinder 2 is filled with oil or other liquid the passage of which from one side to the other of piston 4 is by a hole partially closed by a bolt 8 which may taper outwardly from the centre. Two or more springs in parallel may be substituted for spring 9. The arrangement is such that exact correspondence between control column and elevator movement obtains until a given load on the elevator is exceeded either due to excessive movement at a low speed or to the increased air pressure at high speed. When this pressure is exceeded spring 9 begins to yield and the spring and control system is so arranged that the maximum pitching moment obtainable with full control column movement at maximum velocity is insufficient to produce an acceleration greater than that for which the wing structure is designed. The effect of the damping device is to make the resilient link momentarily " solid for abrupt emergency manceuvres even at high speeds. In order to increase the range during which effective correspondence between control column and elevator movement is maintained, resilient means may be associated with a linkage designed to give a variable transmission ratio. In one form, Fig. 7, the end of rod 67 leading from the control column is constructed as a housing 68 for an initially loaded spring 69 located by a plate 70 and stops 71. Arms 72 extending from the housing carry discs or rollers 73. To each roller is pivotally connected a link 74 connected to plate 70 and a link 75 connected to rod 76 leading to the elevator. In another form an initially compressed spring is arranged between opposed pivots of a parallelogram linkage, the other two pivots of which are respectively secured to elevator and control column control rods.