Inline engine (aeronautics)

The major reciprocating-engine alternative configuration is the radial engine, where the cylinders are placed in a circular or "star" arrangement.

But for aircraft, ‘inline’ can also refer to engines which are not of the straight configuration, such as V, H, or horizontally opposed.

An upright engine has the cylinder heads directly above the crankshaft.

By contrast an inverted engine has the cylinder heads directly beneath it.

Widespread examples included the inline de Havilland Gipsy Major used in the de Havilland Tiger Moth, and the inverted-V Daimler-Benz DB 601 used in the Messerschmitt Bf 109.