Patent GB-655832-A (GB)
Title: Improvements in or relating to controls for rotary-wing aircraft
Inventor: WOTTON JOHN
IPC: B64C27/54
Filed: 1948-11-29
Abstract: 655,832. Helicopters. BRISTOL AEROPLANE CO., Ltd. Nov. 29, 1948, No. 30938. [Class 4] A control for a rotary wing aircraft having a pair of spaced sustaining rotors comprises a lever pivotally mounted between its ends for movement in one plane only, means for rocking the lever, a connection from one arm of the lever to a control for changing the direction of lift of one of the rotors, a connection from the other arm to the lift direction control of the other rotor, a mechanism for reversing the movements transmitted from the lever to only one of said rotor controls so that when the lever is rocked there is produced an " identical rotor control," i.e. equal angular movement of the lift vectors in the same sense, and a further independent means for moving the lever bodily in said plane to produce a " differential rotor control," i.e. equal angular movement of the lift vectors in opposite senses. A control column 5, Fig. 1a, which may be duplicated at 8, is mounted on a transmission box 11 for lateral pivoted movements which are transmitted to a depending rod 7. The box 11 is mounted on a tube 6 allowing longitudinal pivotal movements of the column 5. Rods 43, Fig. 1b, universally mounted on ball joints 42 serve to adjust the cyclic pitch of each rotor. The members 44, 45 articulated to the rods 43 are moved to the same extent in the same direction to give identical rotor control by movement of the column 5. Longitudinal pivoting of the column 5 rotates the levers 15, 16 equally in the same sense, links 17, 19 producing corresponding rotation of the T levers 22, 23. The member 44 is thereby moved longitudinally by the links 26, 27 to which it is articulated and, since the motion of the rods 30, 31 connected to the T lever arms 28, 29 is reversed by the levers 32, 33, the member 45 is moved in the same direction and to the same extent. Lateral pivoting of the column 5 rotates the arm 16, integral with the shaft 14 and the arm 18, in one sense and the lever 15, freely rotatable on the shaft 14, in the opposite sense by deformation of the triangulated linkage 12, 13. The resultant opposite rotations of the T levers 22, 23 deforms the triangulated linkages 26, 27 and 38, 39 producing corresponding lateral displacements of members 44, 45. By combining lateral and longitudinal pivoting of the column 5 any desired displacement of members 44, 45 may be produced. The means for producing the differential rotor control comprise pedals 50 which rotate arms 51 connected by a cable 52 passing round a fixed pulley 56 and including chains 49 engaging sprockets 54, 55 rotatable in fixed bearings and carrying, eccentrically mounted thereon, the pivots of the T levers 22, 23. Operation of the pedals 50 thus produces opposite rotation of the sprockets 54, 55 and moves the T levers 22, 23 bodily in opposite directions in parallel planes causing equal and opposite lateral displacements of the members 44, 45. A similar adjustment of the rotor datum pitch settings is effected by a lever 100 which rotates a T lever 78 by means of a shaft 75, eccentric 76 and rod 77. The arms 79, 80 of the T lever are connected by rods 61 and 64, 62, 63 to sleeves 60 on the rotors. A dissimilar adjustment of the sleeves 60, and hence of the datum pitch setting, is effected by a trim wheel 73, rotation of which rotates a screw 71 in a nut 70 attached to a floating lever 69, thereby operating a rod 72 attached to an arm 85 on the shaft carrying the T lever 78. The end bearings 66 of this shaft are eccentrically disposed and thus rotation of the shaft causes vertical displacement of the T lever and hence opposite displacements of sleeves 60. A roller 68 on the lever 69 engages a cam 67 mounted on tube 6. The cyclic pitch and dissimilar datum pitch setting controls are thus interconnected and enable a large propelling on arresting force to be produced in a fore-and-aft direction.