The internal combustion engine, for all its mechanical sophistication, still runs on a 19th-century mechanical idea: pistons rising and falling, a crankshaft spinning, a steam-age architecture ...

Not every engine has a set of pistons that move up and down in a cylinder. The Wankel, or rotary engine, delivers its power with rotational force rather than a reciprocating mass that hammers out ...

If you look at aircraft from the Second World War or earlier, you'll notice that many of them have engines with large frontal areas and cylinders arranged about the propeller crankshaft. This a radial ...