Lacking cooperation from the Pentagon in the making of the film, the set designers reconstructed the aircraft cockpit to the best of their ability by comparing the cockpit of a B-29 Superfortress and a single photograph of the cockpit of a B-52 and relating this to the geometry of the B-52's fuselage. The B-52 was state-of-the-art in the 1960s, and its cockpit was off-limits to the film crew. When some United States Air Force personnel were invited to view the reconstructed B-52 cockpit, they said that "it was absolutely correct, even to the little black box which was the CRM." It was so accurate that Kubrick was concerned about whether Adam's team had carried out all its research legally.