Patent GB-389845-A (GB)
Title: Improvements in and relating to aeroplane control
IPC: B64C3/38
Filed: 1931-06-23
Abstract: 389,845. Aeroplane controls. FORD, H. C., Jamaica, BALLOU, J. M., Forest Hills, MERRILL, A. A., White Plains, BALZER, V. W., Forest Hills, and MERRILL AIRCRAFT CO., Rawson Street, Long Island City, all in New York, U.S.A. June 23, 1931, No. 18131. [Class 4.] An aeroplane has a supporting surface so chosen that the lines of thrust corresponding to different angles of incidence throughout the whole useful range move progressively rearward, in a zone containing the centre of gravity of the machine, as the angle of incidence increases, the surface being pivoted at a point above the centre of gravity or otherwise mounted so that for each angle of incidence given to the plane the line of thrust passes approximately through the centre of gravity. Wings on opposite sides of the machine may be tiltable oppositely to preserve the lateral balance and the amount of the adjustment for a given movement of the control lever may be variable in accordance with the mean angle of incidence. An elevator may be provided for manoeuvring, and stops adjustable in accordance with the position of the plane may prevent movements of the elevator which would increase or diminish the angle of incidence of the supporting surface beyond the designed limits. Fig. 1 shows a plane 1, of the cross section M.12 (National Advisory Committee on Aeronautics), and its lines of thrust for different angles of incidence. By pivoting the plane at B where the lines are most closely convergent and providing hand-operated tilting mechanism as shown, any one of these lines may be caused to pass through the centre of gravity C of the machine which will then be inherently stable longitudinally. Fig. 4 shows a plane mounting giving similar results with an M.5 section. In this case two tubular spars 20, 21 move in slots 18, 19 in the fuselage, the rear spar being engaged by two loops 22 on the opposite ends of a shaft 24 turned by the worm gear shown. Fig. 6 shows a biplane structure comprising two R.A.F.6 aerofoils having 4‹ decalage, 50 per cent stagger and unit gap/chord ratio mounted to turn as a whole about pivots 30 supported above the fuselage. The incidence is varied by a link 56 connected to a transverse crank arm moved by worm gear 51, 52 when a transverse shaft 49 is turned by chain gear 50 from a hand-wheel 46. Ailerons 58 on the lower plane are actuated by cables 59 passed over pulleys on the axis of the pivots 30. Fig. 9 shows a mechanism for tilting two wings on opposite sides of the machine equally or differentially about their front spars. The ends of the rear spars are engaged by the ends of bell-crank levers 81<1>, 81<2> supported on screwed shafts 83<1>, 83<2> which can be raised and lowered simultaneously by the screw and bevel wheel gear shown. The bell-crank levers are interconnected by a link 97 having a ball joint 98 sliding on a lever 99 which is moved by lateral movements of a control lever 106 to effect lateral balancing movements. The lever 106 also controls an elevator through a connection 107. As the shafts 83<1>, 83<2> are actuated the joint 98 is moved up and down the lever 99 and consequently the gear ratio of the lateral control is varied. When the lever 106 is left free the pressures on the two wings automatically equalize. Fig. 14 shows the lower planes of a biplane unit pivoted about an axis in its upper plane above the fuselage, and tilted by the screwed shafts 129<1>, 129<2> actuated by the gearing shown from the hand-wheel 131. A control lever 132 is pivoted on a shaft 133 mounted in bearings on the fuselage and actuates an elevator through a rod 143 and ailerons through a crank bar 135, yoke 136 and the linkwork shown. As the planes are moved to vary the angle of incidence the yoke 136 is moved along the bar 135 which slopes with respect to the shaft 133 and the velocity ratio of the lateral control system is appropriately varied. Fig. 15 shows a plane similar to that shown in Fig. 1, with means for preventing undesirable movement of the elevator at the two ends of the adjustment of the plane. The elevator is connected to two levers 159, 160 pivoted on a hollow shaft 168 to which a lever 172 for controlling the ailerons is fixed. A cam block 162 is moved in the shaft by connections to the plane tilting mechanism and in one extreme position a horn 177 on the lever 159 is engaged to prevent forward movement of the lever and in the other extreme position a horn 178 on the lever 160 is engaged to prevent backward movements. In intermediate positions the elevator is free to be moved in either direction. Specifications 7237/11, 12448/11, and 154,879, [all in Class 4, Aeronautics], are referred to.