N class blimp http://en.wikipedia.org/wiki/N_class_blimp
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“The follow-on and larger AEW blimp was the ZPG-3W, the largest non-rigid airship ever built. It was used to fill radar gaps in the North American early warning network during the Cold War between the Contiguous Barrier and the Inshore Barrier. The popular name for the ZPG-3W was Vigilance. The ZPG-3W was unique in that the huge antenna for the early warning radar was enclosed inside the helium filled envelope. Four airships were delivered to the U.S. Navy.

The first flight of the ZPG-3W was in July 1958. The envelope of the blimp was used as a radome for the 42 ft (12.8 m) radar antenna, thus providing the airship with a clean aerodynamic shape. The airship was over 400 ft (121.9 m) long and was almost 120 ft (36.6 m) high. The endurance time for the airship could extend for days.

The ZPG-3W was the last of the airships built for the U.S. Navy. The July 6, 1960, crash of a Lakehurst-based airship east of Long Beach Island killed 18 sailors, a loss that added pressure on the program. The Navy decommissioned its airship units on Oct. 31, 1961. On Aug. 31, 1962, the last two ZPG-3W ships made a ceremonial last flight over Lakehurst — the base log noted, “This flight terminates operation of non-rigid airships at Lakehurst,” Steingold said.”

Akron, Ohio – World’s largest blimp by Navy launched, carries radar antenna ” a valuable addition for America’s early warning system”

Volume: Length: 1,500,000 cubic feet 403 feet
Static Lift: 22,360 lbs
Crew: 25 (varied)
Max Speed: 82 kts
Normal Cruise: 45 kts