Patent GB-1002560-A (GB)
Title: Rotor for a helicopter
IPC: B64C27/54
Filed: 1961-11-27
Abstract: 1,002,560. Folding helicopter rotor blades. KAMAN AIRCRAFT CORPORATION. Nov. 27, 1961. [Dec. 1, I960], No. 42394/61. Heading B7W. A helicopter rotor has a plurality of blades, each having an inboard member 20 connected to a rotor hub 18, a lifting structure 46, and inner and outer members 36, 48, the member 36, Fig. 5A, being rotatably mounted on member 20 and member 48 being fixed to structure 46 and pivoted to member 36 by pivot 98 which is angularly adjustable with respect to a plane through the rotor axis, a retaining device 128, Fig. 4, preventing or permitting the folding of members 36, 48 about pivot 98. Tension-torsion members 42 connect members 20 and 36 and resist relative rotation of these members. Pitch control is through a servo-flap operated via lever 52, Fig. 2, pivoted to hub 18, bellcrank 56 on member 20, link 60, lever 62, rods 66, 68 pivoted together by pivot 106, and rod 74. The pivots 106 and 98 are coaxial to prevent folding of the blades interfering with the pitch adjustment mechanism. Pitch lock member 84 pivoted to member 20, Fig. .4, is spring-biased to engage in a notch in a ring 76 on member 36 when the rotor is stationary or rotating below a predetermined speed; above this speed centrifugal force releases the catch. Folding mechanism,-Upper and lower arms 112, 114, Figs. 4, 5A, 8, on member 48 are forked at 120 for engagement with retaining device 128 which comprises two parts 132, 134 slidable on part 130 of member 36 and having inclined recesses 154, 156, 158 for engagement with forks 120; the parts 132, 134 have flanges 146, 148 riveted to part-cylindrical members 136, 138 surrounding and engaging part 37 of member 36; the parts 132, 134 are also connected with members 136, 138 by bolts 150 and spacers 152, Figs. 4, 8. Parts 132, 134 are moved together to grip part 130 when forks 120 engage in recesses 154, 156, 158. A bail 160 pivoted at two points 162 to part 37, Fig. 4, 5A, has two links 164 pivoted to members 142, 145 fixed to members 136, 138. Angular adjustment of pivot 98.-The ring 76 is connected to a ring 170 splined to part 37 and having teeth 176 adjacent teeth 174 on member 20. With the pitch lock member 88 disengaged, the blade and hence pivot 98 can be rotated to a required angle against the resistance of tension-torsion members 42, the ring 170 is then moved to engage teeth 174, 176 to prevent any further rotation. The ring 170 is connected by cylinders 182; 184 and rods 186, 188; with members 142, 145; a third cylinder and rod 202, 204 may connect ring 170 to member 136, Fig. 4. Springs 194, 196, 200 surround rods 186, 188, 204. When bail 160 is rotated from the position shown in Figs. 2, 4, to withdraw retaining device 128 from arms 112, 114 to permit the blade to fold on pivot 98, the ring 170 is moved to engage teeth 174, 176 to retain member 36 and hence the blade and pivot 98 in position; springs 194, 196, 200 hold the ring 170 in its inner position, Fig. 12, not shown. A spring-biased catch 208 on part 37 retains bail 160 in the position where device 128 is released and teeth 174, 176 are engaged; these teeth are engaged before device 128 is released. All the rotor blades can then be folded as for example in Fig. 1, not shown.