[knew it all the time]

Mustangs and Spitfires had in-line engines. Radials were used by the thousands duriing WW II.

[kylaka]

That was my point. There never was a carrier based in-line water cooled engine. They weren't reliable enough.

[calex59]

Yep, the FW 190 had a radial, and it was as fast(faster than most) as any other fighter and more reliable than the ME109(I refuse to call it a BF109). The P47 also had a radial. All bombers had radials.

[KDD]

This is basically a pair of cylinders off a Rolls Royce Merlin aero engine originally fitted to a Mosquito bomber.

Lucky Keizer's 5 litre V twin.