Adams-Farwell Rotary Engine
The Adams-Farwell Rotary Engine was a unique type of engine used in some cars and airplanes in the early 1900s. This engine was different from traditional piston engines because it used a rotary design, which means that the engine spun around a fixed crankshaft. This design allowed the engine to run more smoothly and produce more power for its size. Although it had a small size, it also had great power (via Smithsonian).
The Adams-Farwell engine was also known for its fuel efficiency and could run on a variety of fuels, including gasoline and kerosene. Despite its innovative design, the Adams-Farwell engine was not widely adopted due to its high cost and complexity, and it was eventually phased out in favor of more traditional piston engines.