It's the stuff of legend: goggles, leathercaps, and fluttering white scarves, brightly-colored canvas-and-wood aircraft clashing in battle, just barely past the fledgling stage of human flight. The ...

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 ...