GB597082A - Improvements in or relating to rotary wing aircraft - Google Patents

Abstract

597,082. Helicopters. SPERRY GYROSCOPE CO., Inc. Aug. 10, 1945, No. 20574. Convention date, Aug. 10, 1944. [Class 4] Airfoil section blades 21 are carried on a ring 35 rotatable about a portion of an aircraft body 11, which portion in the example shown is the lower part of a pilot compartment with a cover 15 of moulded transparent plastic material. Each blade 21 is carried by a universal joint 43 on an arm 38 formed on the top of ring 35, which is rotated by gear-ring 36 bolted to ring 35. The lift exerted by the rotating blades 21 upon ring 35 is transmitted through rollers 33 to a circular track 25 supporting vertical members 24 of the body 11. The rollers 33 are mounted on a floating ring 71 within ring 35 and are interposed between bearing surfaces 32 and 34 of track 25 and of ring 36 respectively. Guide rollers 54 under the arms 38 engage a sloping surface of track 25 and provide support for the blades and ring 35 when the blades are not lifting. Simultaneous pitch-control of all the blades is obtained by raising or lowering a control-ring 97 to turn each blade about its longitudinal axis by means of a roller-carrying lever-arm on each blade shaft. A socket 42, in which each blade 21 is mounted in bearings, is connected for flapping and drag movement to universal joint 43. Cyclical variation of pitch is obtained by tilting the control-ring 97 about a longitudinal or transverse axis. A roller 96 actuated by ring 97 is mounted on shaft 92 universally connected as shown in Fig. 4 to the root 51 of blade 21. For the simultaneous pitch-alteration, lever 18 is used to apply hydraulic pressure to cylinder 116 to rotate a rim 111 against return-spring 119 to actuate bell-crank levers and lift the pitchcontrol ring 97 bodily to increase the pitch. In case of engine failure a governor-controlled valve 121 connects the hydraulic system to a sump and so allows the spring to return the rim 111 to a position setting the blades for autorotation. Cyclic variation is obtained by the use of the joy-stick 17 to rotate shafts 141, 132 to tilt the control-ring 97 about a transverse or longitudinal diameter by the lever systems connected to the shafts. In case of failure of the hydraulic system for pitch-control the rim 111 may be actuated by a separate manual control, whose operation also serves to open a byepass valve of the hydraulic system. Damping-means for drag movements of the blades comprise cylinders 40, Fig. 6 ; connecting rods 23 are provided between adjacent blade mountings.