1933. Aluminum, 8 × 2 3/4" (20.3 × 7 cm)
The outboard propeller, designed by the Aluminum Company of America (Alcoa), is a marine propeller, a type of screw with two or more blades that propels an object through air or water when spun by a motor. This propeller was designed for use on a boat. When the motor spins, the screw rotates, causing its blades to push water back and down. Water then fills into the space left by the blade, propelling itself—and the boat it is attached to—forward.
The outboard propeller is made of aluminum, a metal used to create objects as diverse as airplanes, canteens, chairs, trains, cookie sheets, bicycles, and walkers. It is both ductile and malleable, which means that it can be pulled into thin wire and rolled into foil.
The ability to alter a material’s shape under compressive stress, such as hammering or rolling.
The ability to alter a material’s shape under tensile stress, such as stretching or pulling.
Precious Metal When aluminum was first discovered in the 19th century, it was as rare and as prized as gold. Due to improved manufacturing processes, it is now common and exists in a variety of forms.