Patent GB-800890-A (GB)
Title: Directional control system for rotary wing aircraft
Inventor: RYAN JAMES VINCENT
IPC: B64C27/54
Filed: 1956-06-26
Abstract: 800,890. Rotary wing aircraft. GYRODYNE CO. OF AMERICA, Inc. June 26, 1956, No. 19726/56. Class 4. A rotary wing aircraft having two rotors rotating in opposite senses at a predetermined speed ratio has means for controlling the heading comprising aerodynamic brakes at the blade tips and means for selectively actuating the brakes to obtain a torque differential to rotate the aircraft in yaw. Fig. 1 shows the control system. Each rotor 3, 4 comprises two blades 5 having aerodynamic brakes 6 and connected to a hub 10 on pitch change axes. The pitch of each blade is adjusted by a horn 11, those of the upper rotor being connected by rods 20 to the upper element 19 of a swash plate 16, the lower element 17 thereof being connected by rods 18 to the upper element 14 of a swash plate 12. The horns 11 of the lower rotor blades are connected to element 14 by rods 15. The swash plate 12 is tiltable and movable axially for cyclic and collective pitch of the lower rotor, and carries swash plate 16 with it to impose similar pitch change on the upper rotor. The rods 15, 18, and 20 may be adjustable to trim the pitch of each blade. The swash plates are controlled by a cyclic pitch lever 22 and a collective pitch lever 21. The latter is pivoted on a shaft 24 and carries a shaft 28 on levers 29. Shaft 28 supports a bell crank lever 30 and a three armed lever 34. Fore- and-aft movement of lever 22 rocks lever 34 through a linkage 36, 35. This actuates linkages 37, 38 differentially and tilts the lower element 13 of swash plate 12 through arms 39, 40. Lateral movement of lever 22 rocks lever 30 through a linkage 27, 31, and this, through linkage 32, tilts element 13 through an arm 33. Operation of lever 21 raises or lowers shaft 28 to actuate the linkages 32, 37, 38 equally. The brakes 6 are actuated by pedals 44 connected by a linkage 46, 47, 49 to a rod 50 inside the rotor shafts. A rotary head 51 at the top of rod 50 is connected by links 52 to bell crank levers 53 connected to rods 54 actuating the brakes of the upper rotor. Links 55 depending from head 51 are connected to a hollow shaft 57 through a rotating collar 56. Shaft 57 is connected through links 59 to bell crank levers 60 connected to rods 54 actuating the brakes of the lower rotor. When rod 50 is raised, the rods 54 of the upper rotor move radially inwards and the correspond ing brakes are actuated, while the rods 54 of the lower rotor move radially outwards and the corresponding brakes remain inactive, and vice versa. A rudder 61 is settable by cables 64 and a worm gear 65, 66 and mounts a further surface 67 coupled by rod 70 to the pedals 44. The rods 15, 18, and 20 are adjusted in length so that the aircraft heading remains steady in hovering flight with the surfaces 61, 67 in neutral position. The rudder 61 is then trimmed so that the heading remains steady during forward flight at crusing speed, so that the pedals 44 are actuated only when a change in heading is required. The brake may comprise a flat triangular or cylindrical member moveable radially outwardly from the blade tip by a rod 54, or may be a split trailing edge flap which is opened by rod 54 to increase the drag. Another form is shown in Fig. 6 as a member 82 pivoted to the blade tip at 83 and to a lever 85. A lever 86 is pivoted to the blade at 87 and to lever 85, and has a roller 88 engaging a slot 89 in a pulley 90 on a fixed shaft 91. The slot comprises a circular arc 98 centred on shaft 91, and an inwardly spiraling portion 99. Pulley 90 is rotated by rod 54 through a cable 92 and guide pulleys. When rod 54 moves outwardly, the roller works in the arc 98, and lever 86 stays fixed. When rod 54 moves inwardly, the roller moves in arc 99, and lever 86 pivots to extend the brake member 82. A further form of brake is shown in Fig. 10 as comprising a plate 112 of large area as seen looking along the blade and of greater depth than the blade, attached to a web 113 pivoted to the blade at 114. A spring 123 normally keeps the plate and web in the position shown in full lines. A roller 116 on a lever 117 pivoted to the blade at 118 engages a slot 115 in web 113, composed of a circular arc 115A centred on pivot 118 and an inwardly directed portion 115B. Lever 117 is actuable by a cable 154 corresponding to rod 54. When the cable moves outwards roller 116 moves in arc 115A, and the brake remains inactive. When the cable moves inwards, roller 116 moves in portion 115B of slot 115, and the web 113 and plate 112 are moved outwardly as shown in chain dot lines.