Curtiss Model K-12 Engine and Model 18-B Airplane, circa 1919

Glenn Curtiss established what would become the Curtiss Aeroplane and Motor Company in 1909. The company achieved success -- especially as military orders soared during World War I -- but Curtiss also endured failure. The promising 400-horsepower K-12 engine (pictured here, left) ultimately proved to be unreliable, and the model 18-B airplane (right) was never put into production.