Patent GB-136003-A (GB)
Title: Improvements in Means for Adjusting the Blades of an Airscrew During Flight.
Inventor: RUSSELL WILLIAM COLIN
IPC: B64C11/36
Filed: 1919-01-14
Abstract: 136,003. Russell, W. C. Jan. 14, 1919. Screw propellers.-Relates to air propellers having blades adjustable during rotation. The propeller shaft A, Fig. 1, is provided with a tubular T-piece A' in which a sleeve B carrying one of the blades is rotatably mounted. The opposite blade carries a pivot C which passes through the sleeve B and is also free to rotate. The blade is, in each case, attached to plates. B<1>, C<1> carried by the sleeve and spindle B, C. A thrust ball bearing C' is provided between the plate B' and a nut C<3> screwed on the end of the spindle C. The centrifugal forces due to the two blades are balanced, and no force is transmitted to the supporting-frame A<1>. A second pair of blades may be placed at right-angles, in order to make a four-bladed propeller. In order to vary the pitch of the blades during rotation, the plates B', C<1> are provided with levers B<2>, C<2> having pins B<21>, C<21> which engage in a helical groove D<1> cut in a drum D. The groove is right-handed for 180 degrees and left-handed for 180 degrees, so that when the drum is rotated on its axis D<2>, the two levers are moved in opposite directions. In an alternative form, the drum may be replaced by a rotatable tilted disk. The drum may be rotated by any means such as the electrical device shown in Fig. 3. The axle of the drum D carries a worm-wheel D<4> driven by a worm E<1> mounted on the shaft 8, which carries the worm-wheel E<2> driven by a worm F' carried by a cross-shaft F. The shaft F carries a bevelwheel F<2> at the other end, meshing with two bevel-wheels G<2>, G<3> mounted on a constantly rotating shaft G. This shaft carries a gear-wheel G<1> engaging with the stationary annular wheel H, so that during rotation of the propeller, the wheel G<1> revolves around the axis of the shaft A, and the shaft G is rotated. The wheels G<2>, G' are adapted to be clutched to the shaft G by the pins G<4>, G<5> when these are expanded outwards by the tapered wedge bar G<6> within the hollow part of the shaft G. The bar G<6> is connected with the lever K which carries iron blocks K<1>, K<2> close to the electro-magnets L<1>, L<2>. The magnets may be selectively energized so that one or other of the wheels G<2>, G<3> is clutched to the shaft G, and the drum D is correspondingly rotated in one direction or the other. In the modification shown in Fig. 4, a method of attaching a wooden blade to the metal socket is shown. A conical split metal socket P is bolted to the plate B', and is secured to the blade end R by binding with strong wire P<2>. Flanges P<1> are provided to prevent slipping of the wire. Fig. 6 shows an alternative method of driving the drum D. The drum axle D' carries a worm-wheel D<4> driven by a worm E<1> mounted on a shaft E. This shaft carries a chain-wheel E<3> connected with the chain-wheel S<1> mounted on a sleeve S which is free to rotate on the shaft A. The sleeve S carries drums S<2>, S<4> provided with band brakes T', T<2> by which they may be prevented from rotating. During rotation of the propeller, the drum D may be driven in either direction by restraining one or other of the drums S<2>, S'. A modification is also described in which the shaft A is of ordinary form and carries a frame provided with bearing-rings for the blade sleeves. A slightly modified construction of these sleeves is shown, and the drum D is located on one side of the main shaft A.