Thanks for confirming it's a B-17. Surprised they were still operational in the late1950s.
On the others - on the apron a Nord Noratlas and a C-54?.
More interesting on the runway is an USN EC-121.
From wiki - The Atlantic Barrier (BARLANT) was to extend early warning coverage against surprise Soviet bomber and missile attacks as an extension of the DEW Line.
BARLANT became operational on 1 July 1956, and the EC-121's flew continuous coverage until early 1965. Their mission was to fly orbits to the Azores and back. The barrier was shifted to cover the approaches between Greenland, Iceland, and the United Kingdom (GIUK) barrier in June 1961.