I remember reading about how in the 1930's they had trouble with radials that had more than two rows due to airflow cooling issues. I remember reading that engines that were developed in the 1940's such as the R-4360 got around this by offsetting the cylinders, forming a semi-helical arrangement.
My questions are
- Didn't the twin-row radials have a cylinder offset as well?
- Why didn't they think of that earlier -- the idea isn't exactly a leap of imagination as it would simply be an extension of the twin-row radials?