Ellehammer "Flyver" Model 1906

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Jacob Christian Hansen Ellehammer, a Danish inventor born in 1871, is renowned for his contributions to powered flight. After completing an apprenticeship as a watchmaker, he moved to Copenhagen and worked as an electronics mechanic before establishing his own company in 1898. Ellehammer initially produced various electronic machinery but later ventured into motorcycles, creating the Elleham motorcycle in 1904. In 1903-1904, he used his expertise in constructing motorcycles to build the world's first air-cooled radial engine, a three-cylinder model that was later upgraded to a five-cylinder version in 1907. Ellehammer installed this powerful engine in his triplane and achieved several short free-flight hops. He also constructed a monoplane in 1905, followed by a "semi-biplane" in which he made a tethered flight in 1906. Among his later inventions were a successful triplane and coaxial helicopter, with the latter even seen hovering in a famous photo from 1914. Ellehammer also experimented with disc-rotor configurations for his helicopters, but there's no evidence that these ever achieved translational flight beyond wind tunnel models.