annular radiator - advantages?

[kennethklee]

What are the advantages and reasons for applying an annular radiator (Focke-Wulf Fw 190D-9, Focke-Wulf Ta 152, inlined-engined Junkers Ju 88, some versions of Hawker Tempest) instead of standard discrete radiator units (Messerschmitt Bf 109, Supermarine Spitfire, North American P-51, Kawasaki Ki-61) to inline liquid-cooled piston aircraft engines? I am curious because visually the annular radiator seems to negate some of the advantages of a liquid-cooled engine, such as drag reduction, decrease of cross-sectional target area, and a streamlined graceful appearance.

Thanks,
Kenneth