GB385101A - Improvements in or relating to helicopter aircraft - Google Patents

Abstract

385,101. Helicopters. NAGLER, B., 59, Rennweg, and HAFNER, R., 47, Mantlergasse, both in Vienna. Dec. 8, 1931, No. 33992. Convention date, Dec. 16, 1930. [Classes 4 and 114.] In a helicopter aircraft of the type having a lifting screw braced for strength and with means for varying the angle of incidence of the blades, the base for the supporting of the screw boss and for the bracing of the blade arms is formed by the inner ring of a ball race of large diameter of which the outer ring is secured to the aircraft frame and the inner ring driven by the engine. The lifting screw comprises blades 9a having blade arms 9 freely socketed in a boss 8 which is supported by pedestal struts 10 fixed to the inner ring 3 of a ball bearing 2 fixed in the body 1. The blades are braced by wires 13 attached to ring 3 and wires 14 attached to the upper end of a strut 11 of variable length mounted in the geometrical axis of rotation of boss 8 and ball race ring 3. Ring 3 is formed with peripheral gear teeth 4 and is driven from an engine 5, Fig. 1, through a free-wheel coupling 7. The wires 13, 14 are attached at their outer ends to sleeves 15 which may be rotatable on, or rigid with, arms 9. The latter carry cranks 16 linked by rods 17 to the outer ring 18 of a universally mounted ball bearing concentric with bearing 2. Pins 21 on ring 18 engage guides 20 on ring 3 so that the two rings rotate together. The inner ring 19 is trunnioned on a universal joint frame 25 articulated to supports 22. Supports 22 may be moved up or down by a lever 24 moving the ball race 18, 19 bodily up or down to cause an equal change of pitch of all the blades. The race 18, 19 can also be tilted in any direction to cause cyclical variation of blade pitch by means of a control lever 26 mounted on the supports 22 and having its free end engaging a socket 28 in a stirrup 27 the upper ends of which are connected to ring 19. Two parallel control surfaces 29 are arranged in the slipstream from the screw and may be inclined from the vertical to oppose the screw back torque. In a modification a horizontal rotor occupies the position of the tail planes and is driven by the engine to produce a magnus effect and thus develop a counter-torque. According to another modification the airscrew boss supports 10 may be replaced by a sheet-metal cone fixed to the ring 3.