Abstract: A propeller according to an embodiment includes a hub and a series of blades extending outward from the hub. Each blade of the series of blades includes a core and a skin covering the core. The core may be formed of a ceramic first material and the skin is formed of a second material different than the ceramic first material. The ceramic first material of the core may be ceramic Si3N4 (silicon nitride), yttria-toughened zirconia ceramic, or alumina-zirconia ceramic, and the second material of the skin may be a polymer. The polymer skin is configured to function as a shock absorber protecting the ceramic core, and the ceramic core is configured to provide rigidity to maintain the shape of the propeller blades under aerodynamic loading, which enables improved aerodynamic efficiency and reduced noise generation.

Abstract: A machine is shown for feeding a length of wire to a forming station, cutting and forming the length into a U-shaped element around an arbor, moving the U-shaped element to a presentation position in a channel of a face plate with the free ends of the element extending out of the face plate, then forming the free ends into a closed loop by means of a forming head engaging the ends and bending them into the loop and finally ejecting the element from the face plate.