N-class blimp

The N-class blimp, popularly called the Nan ship, was a line of non-rigid airships built by the Goodyear Aircraft Company of Akron, Ohio for the United States Navy in the 1950s. It followed the M-class with a much larger helium envelope and two Wright Cyclone radial engines, and was built in anti-submarine and airborne early warning versions as the designation system changed from ZPN-1 to ZPG-1 and later SZ-1A. Its ZPG-2 Snow Bird flew non-stop across the Atlantic and back in March 1957, covering 9,448 miles in about 264 hours and beating the Graf Zeppelin distance record. The ZPG-3W Vigilance, with its radar antenna inside the envelope, was the largest non-rigid airship ever to enter military service, and the Navy ended its blimp operations in 1962.