During the American Civil War, the United States Navy blockaded Southern ports. Southern engineers set their minds to finding technological ways to break that blockade. For example, they built the first submarine that sank another vessel in combat.
William C. Powers, an engineer in Mobile, Alabama, took a different approach. Forty years before the Wright brothers flew, Powers tried to build a warplane:
Although balloons were being effectively used for observation, they lacked directional control and could not lift enough weight to make an effective bomber. Powers drew upon the work of other famous engineers, such as Archimedes and da Vinci, and employed Archimedean screws for lift and thrust, all powered by a steam engine. The engine was located in the middle of the craft, and used two smokestacks, which can be seen in the drawings. Two Archimedean screws on the sides gave the helicopter forward thrust, similar to how a propeller works on a ship in water, and two mounted vertically in the helicopter gave it lift. A rudder was added to the rear of the craft in order to provide steering.
Powers's efforts were unsuccessful, but he did build a model, which is pictured above.
(Photo: National Air and Space Museum)