Patent GB-418109-A (GB)
Title: Improvements in or relating to air screw propellers or the like
IPC: B64C27/02
Filed: 1934-03-16
Abstract: 418,109. Rotary wing systems. PERRIN, E. A., 9, Rue des Charmes, Le Vesinet, Seine-et-Oise, France. March 16, 1934, No. 8400. Convention date, March 17, 1933. [Class 4.] In a rotary wing system in which the blades of the propeller may be locked and the incidence varied when the blades rotate, the blades are connected to a hub by a hinge so as to enable the normal theoretical axis of the blade to be moved from a horizontal position to a position inclined relatively to the axis of rotation about an axis at right angles to the axis of rotation and the hub is capable of being locked or unlocked from the shaft on which it is mounted. As shown the propeller blades may be locked to form a wing in which case the trailing edge of one blade is expanded to form a leading edge or it may be unlocked and driven or rotate to form a supporting surface a variation in the orientation of the blades being effected about a theoretical axis 101, Fig. 1, which under certain conditions may be inclined further to the axis of rotation 102 and to the medial line 103 of the blade. The axis 101 is determined in such a way that during normal rotation the sustaining force 105 on the blade and the centrifugal force 106 give a resultant 107 directed along the axis 103 and the angle 108 to the medial line 103 is such that during normal rotation the centres of the sustaining and centrifugal forces lie behind the theoretical axis of orientation 101. Thus an increase in the force 105 lifts the back of the blade and vice-versa. If the axis 101 is a short distance in front of the centres of the forces 105, 106 the variation of the angle of incidence of the blade is large relative to the variation of the inclination of the axis 103 to the axis 102 hence the force 105 is during normal rotation approximately in constant proportion to the centrifugal force 106 which arrangement automatically eliminates unbalanced couples. The normal inclination of the medial line 103 may be altered by an elastic tie wire 109 and the theoretical axis 101 may be maintained by fixing a point 110 forward of the blade by stays 111, 112, the stay 112 being suspended elastically to facilitate orientation of the blade. The propeller hub 132, Fig. 8, is mounted on roller bearings on a fixed column 133 and an intermediate part 169 of each blade is hinged in a horizontal plane at 168 to the hub. The outer part of each blade is mounted to swivel on a tube 114 and thrust block 175. The blades are provided with hinged ribs 145, Fig. 5, and in the fixed wing position shown in dotted line 181, Fig. 8, the trailing edge of one blade is converted to a leading edge by operating cables 150 to move laterally a double-ended member 142. In the position 181 the outer part of the wing is locked to the intermediate part 169 by bolts 182, Fig. 7, connected by an arm and connecting rod to a pulley 185 operated by cables 138, Fig. 4, and the hub 132 is locked to the column 133 by a pivoted bolt operated by a crank 195, Fig. 12, a safety lock 204 engaging elastically a part 208 to prevent backlash. The change from a fixed to a rotary wing is effected by sliding a shaft 127 into engagement with a shaft 191 driving a pulley 180 to operate cables 112, 109 to raise the blade to full line position, Fig. 8, the cable 112 being elastically mounted on pulley 178, Fig. 8, or elastically suspended at 179. The shaft 127 is driven through shaft 193 by wind vane or power and a cone clutch 210, 211 is engaged by a spring plunger 218 to drive a sleeve 214 by a sprocket 213 and chain. The sleeve 214 drives the hub 132 through a spring operated pawl 224. The bolts 182 are withdrawn to permit the outer part of the blade to orientate either manually or automatically by means of a lever 135, Fig. 4, pivoted to the hub 132 and provided with a roller 130 running on a fixed cam track 134. A link 136 pivoted to the lever 135 operates a pulley 137 and through cables 138 the pulley 185, Fig. 7, operating the bolts 182. If the hub 132 rotates before bolts 182 are withdrawn then the roller 130 rides out of the cam groove and withdraws the bolts. The manual control comprises a plate 140 adapted to be raised by a bell-crank 139. A similar control operates the pulley 177, Fig. 8, to move the double-ended member 141, 142, Fig. 5. The pulleys 177 and 185 are adapted to be locked in the position into which they are moved by an arm on the pulley engaging in recesses in a spring plate.