My previous post about the number of airfields the B36 could land east of the Atlantic was based on the single wheel undercarriage. The reasoning became obsolete at about the same time they added four jet engines. The two pods were, literally, lifted off the Boeing B47. The reason was that with growing weight the aircraft could not meet it designed speed and altitude over its target so it needed more boost; the four jet engines did that. In the normal cruise around the Atlantic they used to shut down two engines and fly around on four.