Patent GB-264963-A (GB)
Title: Improvements in or relating to aircraft with rotative wings
IPC: B64C27/02
Filed: 1925-11-19
Abstract: 264,963. La Cierva, J. de. Nov. 19, 1925. Screw and like propellers.-Relates to the following improvements in the construction and mounting of the blades and their supporting structure of a freely-rotative wing-system of the hind described in Specification 196,594 :-(1) The blades are constructed with sufficient inherent resilience, or they are pivoted at their roots, to permit restricted swinging movements in the plane of rotation. For this purpose the blades may embody a single longitudinal resilient metal spar F, Fig. 2, or they may be mounted on a secondary perpendicular pivot D, Fig. 1. To relieve stresses and prevent excessive displacement, adjacent blades are braced together by flexible cables E. which may include springs E<3>, or which may be normally slack but furnished with weights E<2>, which in rotation tauten the cables. (2) Yielding means are provided for restricting the vertical swinging or beating movement of the blades. A sliding member N, Fig. 6, is mounted inside the blade A between springs O, and connected to the main rotating shaft Q by a link P. The springs 0 do not obstruct useful movement of the blade, but, limit extreme movement. The downward movement only may be limited, if desired, by springing the slide N on one side only. (3) The strength of the blades is increased towards their tips, where the stress is greatest. The lateral ribs G, Fig 2, are made of increasing strength and stiffness, or as shown are set progressively nearer to one another towards the tip, which may be further strengthened by a covering H of metal or plywood. The resultant additional weight at the wing tip also increases the centrifugal component. In a modification, this covering is restricted to the extreme tip and its inner edge is made parallel to the ribs G. (4) Auxiliary stays are provided lengthwise of the blades to relieve the spars of tension stresses due to centrifugal action. In the arrangement described, the spar I. Fig. 5, is hollow and a steel cable K running through it is secured at one end to the hinge mounting of the blade and at its outer end to an eye-bolt L carrying a washer L<1> bearing on the end of the spar. The spar is put under compression by tightening a washer L<2>. (5) Means for adjusting the weight and centre of gravity of the blades are provided comprising metal discs L<3>, Fig. 5, which are threaded upon an extension of the eye-bolt L and secured by a nut L<4>. An aperture with a closing member is provided in the blade tip for the accommodation of this apparatus. (6) An improved mounting for the wing-system comprises a, sleeve 11 bolted over the upper end of the hollow supporting shaft 10, and terminating at its lower end in a ball race 12, which with a race 13 forms a thrust bearing which supports the machine on the wing- system in flight. The race 13 with both races 14,15 of a second thrust bearing are carried by a ring 16 formed in one with a rotary sleeve 17 and a member 18 which carries roller bearings 19 for the hinge joints. Radial bearings 20, 21 at the top and bottom and a thrust bearing 22 support the wing system when the aircraft is on the ground. Lubricant contained in a receptacle 23 secured to the part 17 lubricates the upper bearings and travels through the space 24 to the lower bearings 21, 22, some also being thrown out through ducts 25 to the bearings 19. A revolution counter or speed indicator for the wings may be driven through gearing 27, 28.