Inline engine (aeronautics)

In aviation, an inline engine is a reciprocating engine with banks of cylinders, one behind another, rather than rows of cylinders, with each bank having any number of cylinders, although more than six is uncommon. The major reciprocating-engine alternative configuration is the radial engine, where the cylinders are placed in a circular or "star" arrangement. The term "inline" is used somewhat differently for aircraft engines than automotive engines. For automotive engines, the term ‘inline’ refers only to straight engines (those with a single bank of cylinders). But for aircraft, ‘inline’ can also refer to engines which are not of the straight configuration, such as V, H, or horizontally opposed. Straight Engines with a single bank of cylinders which can be arranged at any angle but typically upright or inverted, (e.g. upright ADC Cirrus, inverted de Havilland Gipsy Major). VEngines with two banks of cylinders with less than 180° between them driving a common crankshaft, typically arranged upright or inverted (e.g. upright Liberty L-12, inverted Argus As 410). O or Horizontally Opposed Engines with two banks of cylinders arranged at 180° to each other driving a common crankshaft, almost universally mounted with banks horizontal for aircraft use, or with crankshaft vertical for helicopter use, (e.g. horizontally mounted Continental O-190, vertically mounted Franklin 6ACV-245). WEngines with three banks driving a common crankshaft, arranged so that first and last banks are 180°or less apart, (e.g. upright Lorraine 12Eb, inverted Napier Lioness). X Multiple bank engines with four banks arranged around a common crankshaft, usually spaced evenly, (e.g. evenly spaced Rolls-Royce Vulture, unevenly spaced Napier Cub). Fan Engines with more than three banks with 180° or less between first and last bank, akin to W engines. Note: Fan engines with single cylinder banks, typically from Anzani, are usually regarded as variants of the Radial engine. UEngines with two banks of cylinders side by side driving separate crankshafts geared to a single output, (e.