page_title: Flat-twin engine
hierarchical_section_title: Flat-twin engine
caption_attribution_description: Douglas motorcycle Abergavenny steam rally, 2012.
context_page_description: A flat-twin engine is a two-cylinder internal combustion engine with the cylinders on opposite sides of the crankshaft. The most common type of flat-twin engine is the boxer-twin engine, where both cylinders move inwards and outwards at the same time.
  The flat-twin design was patented by Karl Benz in 1896 and the first production flat-twin engine was used in the Lanchester 8 hp Phaeton car released in 1900. The flat-twin engine was used in several other cars since, however a more common usage is in motorcycles; early models oriented the cylinders in line with the frame, however later models switched to the cylinders being perpendicular to the frame to provide even cooling across both cylinders.
  Flat-twin engines were also used in several aircraft up until the 1930s and in various stationary applications from the 1930s to the 1960s.
context_section_description: A flat-twin engine is a two-cylinder internal combustion engine with the cylinders on opposite sides of the crankshaft. The most common type of flat-twin engine is the boxer-twin engine, where both cylinders move inwards and outwards at the same time.
  The flat-twin design was patented by Karl Benz in 1896 and the first production flat-twin engine was used in the Lanchester 8 hp Phaeton car released in 1900. The flat-twin engine was used in several other cars since, however a more common usage is in motorcycles; early models oriented the cylinders in line with the frame, however later models switched to the cylinders being perpendicular to the frame to provide even cooling across both cylinders.
  Flat-twin engines were also used in several aircraft up until the 1930s and in various stationary applications from the 1930s to the 1960s.
caption: Douglas 80 Plus motorcycle engine (circa 1950)
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