The RB-36 is a reconnaisance variant of the B-36. The B-36 was developed to bridge an ocean to protect the US in case England was lost to the Germans. It had nearly a 10k mile cruising range and could stay aloft more than 48 hours. Unfortunately for it, the jet age began after WWII and for some (especially the US Navy) thought it shouldn't have seen the light of day. The Navy wanted more carriers, of course, and didn't think that the government should spend money on a new bomber. They lost that argument.
The B-36 was a hybrid of sorts as it had 6 rotary engines and 4 jets. The wingspan was so large that inflight maintenance could be performed, if necessary, as there was sufficient room to crawl into the wings.
The RB was a platform for the Boston camera and they were used to photograph many of the east block countries in it's day. They were solitary aircraft for the most part and very rarely traveled in any formation. The B's usually traveled in packs of three.
The B/RB-36 kept the Russians at bay until the B-52 was fully operational, mid to late 50's. The jets of the early 50's could not fly high enough (with any power) to shoot it down. The advent of surface to air missiles, however, was another nail in it's coffin and by 1959 all were smelted down...
My dad was crew chief at Ellsworth in the early 50's on the RB. I've linked a picture of his aircraft (748). It was one of the longest surviving aircraft as it was used in nuclear airborne testing in the summer of 1958 as an observer aircraft.
http://www.flickr.com/photos/12675355@N04/2279730356/#in/set-72157603949465943