GB499932A - Improvements in or relating to screw propellers, particularly for aircraft - Google Patents

Abstract

499,932. Airscrews. REISSNER, H., and ARGUS MOTOREN GES. May 3, 1938, No. 13183. [Class 114] A variable-pitch propeller in which the blades are mounted to turn freely about the longitudinal axis at right-angles to the propeller shaft, and also about a pivot disposed on a transverse axis with respect to the propeller shaft, such disposal and the distance of axis from the propeller shaft are so chosen that the blade under the combined action of the engine torque engine thrust and centrifugal force is automatically adjusted to the desired pitch. A boss 1 carries a number of adjustable sockets 2 in which is mounted a sleeve 5 turnable in relation to the socket upon the ball race 4. This sleeve 5 carries a transverse pin 7 upon which is mounted a second socket 9 to which the root 8 of the blade is attached. Adjustment of the pin within the sleeve 5 is effected by the screwed carrier 6. In an alternative the blade root 9 is provided with a sleeve carrying a number of sphericalshaped discs 13 adapted to coact with corresponding shaped discs 11, 12 carried by the sleeve 2 that is screwed in a socket in the hub. A lower spherical member 16 is provided with a transverse slot and engages a key 17 on the lower spherical surface 14. In a modification the spherical surface is reversed and the root of the blade 23 has a spherical bearing surface 21 upon a spherical surface 20 on the sleeve carrier 2. For the purpose of providing a vertical transverse axis, a pin 24 is continued inwardly and provided with a curved key engaging a slot 17 in a sleeve 16. The key may be held in place by a spring 27 so that it can be raised clear of the slot when it is desired to rotate the sleeve 16 and readjust the position of the slot. Alternative to setting the groove to fixed positions, it is possible to arrange for a relative movement during rotation as by the use of the centrifugal weight 38, the stem of which moves the key member 17, but moves it along a slightly helical path 36 whereby new settings are effective. These settings may only become effective at particular speed ranges of the plant as by providing either a very stiff spring 39 or a weak one in which case the centrifugal weight remains inoperative above or below a certain range of speeds. Alternatively, instead of an automatic centrifugal control, the control may be effected by using a piston 41 similarly coupled to the surface 17, the piston itself being moved by liquid lead thereto through a pipe 43 under the control of the pilot.