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, but rarely more than six.

Note: Fan engines with single cylinder banks, typically from Anzani, are usually regarded as variants of the Radial engine.

Note: There is no theoretical limit to the number banks in an opposed piston engine, limitaions include cost, complexity and reliability.

Note The BMW 803 is not only an inline radial engine but is also a coupled engine with two engines arranged back to back on a common axis driving separate co-axial propellers through a common gearbox.

Some inline aircraft engines, including the de Havilland Gipsy Major used in the de Havilland Tiger Moth, and the Daimler-Benz DB 601 used in the Messerschmitt Bf 109, were designed to be installed in airframes inverted, such that the crankshaft was at the top of the engine and the cylinder heads were at the bottom. The advantages of inverted engines included improved visibility for the pilot, improved access to cylinder heads and manifolds for the ground crew, having the centre of mass of a multi-bank engine lower in the engine, and having the widest part of a multi-bank engine being closer to the midline of the fuselage, which is also generally wide.

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