ZPG-3W

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The Goodyear ZPG-3W was a very large airborne early warning non-rigid airship built by the Goodyear Aircraft Company for the United States Navy. The airship was powered by two Wright radial air-cooled engines. 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 Reliance. The ZPG-3W was unique in that it was the largest non-rigid airship ever built and 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 ZPG-3W was developed as a follow-on to the ZPG-2W airship which was a modification of the ZPG-2, a blimp built for maritime patrol missions. The first flight of the ZPG-3W was in July 1958. The envelope of the blimp was used as a "radome" for the 42 foot (12.2 m) radar antenna, thus providing the airship with a clean aerodynamic shape. The airship was over 400 feet (120 m) long and was almost 120 feet (36 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 and remained in operational service until they and all other Navy airships were deactivated in November 1962 when the U.S. Navy ended airship operations. The specially designed and built AN/APS-70 Radar with its massive 42 ft. internal antenna was the best airborne radar system built for detecting other aircraft because its low frequency penetrated weather and showed only the more electronically visible returns.

Under the 1962 unified Department of Defense air vehicle designation system the ZPG-3W was re-designated the EZ-1C.

[edit] Specifications

Crew: Twenty Four(approx.)
Volume: 42,967 cu m (1,516,300 cu ft)
Length: 123 m (404 ft)
Width: 25.9 m (85 ft)
Height: 36 m (118 ft)
Lift: 10,409 kg (22,900 lb)
Empty: kg ( lb)
Loaded: kg ( lb)
Powerplant: two, Wright R-1820-88 Cyclone 9 cylinder, radial air-cooled engines, 1,138 kW (1,525 hp)
Maximum speed: 145 km/h (90 mph)