GB859007A - Improvements in or relating to thrust and/or lift producing devices for use in a fluid medium - Google Patents

Abstract

859,007. Endless band propellers. MATTHEWMAN, W., and WILLIAMS, E. H. Oct. 22, 1958 [July 23, 1957 ; Nov. 23, 1957 ; Jan. 1, 1958], Nos. 23214/57, 36563/57 and 4/58. Class 4. A lift and/or thrust producing device for use in a fluid medium comprises a plurality of blades travelling in unison through the medium round an endless path, each blade being pivotable about a hinge between an operative, position on a working run in which the working surface of the blade is held facing the direction of travel, and an inoperative position on an idle run in which the blade is held edgeon to its direction of travel, the blade having portions of its working surface on each side of its hinge. In the Figure, which shows an application to lifting aircraft three blades 16, 17, 18 are supported between two flexible chains 14, or bands, (one only shown) by hinge axles 15. The chains run over sprockets 12, 13, the latter being rotated by a shaft 11. The arrangement is that only one blade, e.g. blade 16, is on the thrust or lift producing run at any time. This blade moves through the air in the direction of arrow 28 and the pressure on the blade keeps it pressed against a stop 24 integral with one link of the chain 14. On completing the run, a roller 40 on the blade engages a spiral section 42 of a guide surface 41, which rotates the blade relatively to the chain, so that by the time the blade (e.g. blade 17) commences its return run, it is aligned with its direction of travel. This rotation stresses a leaf spring 25 attached to the stop 24, this spring keeping the roller 40 in contact with guide 41. When roller 40 leaves guide 41 at the end of the return run (e.g. blade 18) the leaf spring rotates the blade to abut stop 24 again, in which position it is again held by fluid pressure on the working run. As an alternative to springs 25, a flange 45 may be provided on each blade, having the same effect through aerodynamic causes. In an alternative embodiment, each blade is disposed about its hinge axle 15 so that the stops 24 are disposed towards the inside of the space enclosed by the flexible chains, and the guide rail 41 is disposed outside this space. Aerodynamic effects are relied on to rotate the blade relatively to the chain at the end of the working run. The device may be adjustable to provide thrust and lift, either by tilting of the whole device, or by movement of idling shaft 10 angularly about shaft 11. During the working run, the blades may travel through a duct in which they are a working fit. The devices may be used in contra-rotating pairs. They may also be used totally submerged in a liquid medium. Each blade may be flat and rigid, or may comprise a framework over which rubberized fabric is stretched by tensioning springs.