N-Class Blimp

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The N-Class, or as popularly known the Nan ship, was a line of non-rigid airships built by the Goodyear Aircraft Company of Akron, Ohio for the US Navy. This line of airships was developed through many versions and assigned various designators as the airship designation system changed in the post World War II era. These versions included airships configured for both anti-submarine warfare and airborne early warning (AEW) missions. The initial version, designated ZPN-1, was a follow-on to the M-class blimp for patrol missions. The Nan ship used a significantly larger envelope than the M-ship although their overall lengths were similar. Two Wright radial air-cooled engines powered the N-Class blimps.

An initial contract was awarded to the Goodyear Aircraft Company for the prototype N-class blimp in the late 1940s, with delivery in early 1950s. The ZPN-1 designation was changed to ZPG-1 in 1954, and then to SZ-1A in 1962. The envelope capacity for the ZPN-1 was 875,000 cu ft (24,777 m³) and used the gas helium for lift.

The ZPN-1 was followed by an order for four improved N-class blimps that were delivered in 1954. These airships were designated ZP2N, and re-designated in 1954 as the ZPG-2. Three of the ZP2N airships were modified for an airborne early warning mission in the mid 1950s and were designated, originally, ZP2N-1W but at delivery were designated ZPG-2W. Their designation was changed to EZ-1B in 1962. The envelope capacity of these airships exceeded 1,000,000 cu ft (28,317 m³). The ZPG-2W was equipped with the AN/APS-20 radar with its antenna installed inside the envelope. An AN/APS-69 height-finding radar antenna was mounted on top of the envelope. The airship carried a crew of 21 and had an endurance of over 200 hours. Also, the engines were installed in the control car, driving the propellers through extended shafts. The first ZPG-2W was delivered to the Navy at NAS Lakehurst in May 1955.

Operationally the ZPG-2W 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. In a demonstration of the ability to stay on-station for extended times, in a record making flight, a ZPG-2W flew a circuit non-stop from NAS Lakehurst, New Jersey to west Africa and onto Key West, Florida covering a distance of 8,216 miles in 264 hours.

The follow-on and larger AEW blimp was the ZPG-3W. These airships remained in service until the Navy’s lighter-than-air operations were suspended in November 1961.

1 Designation Systems
- 1.1 Specifications (ZPG-2W)
  - 1.1.1 General characteristics
  - 1.1.2 Performance

[edit] Designation Systems

Under the designation system established in April 1947 the first N-class airships were given the Navy designation of ZPN-1, (Z = lighter-than-air; P = patrol; N = type/class). In April 1954, the designation system was changed to mimic that used for heavier-than-air aircraft. With this change the designation for the ZPN-1 became the ZPG-1 (Z = lighter-than-air; P = patrol; G=Goodyear; 1=first version). In the 1962 system the ZPG-1 designation was changed to SZ-1A (S=anti-submarine warfare; Z=lighter-than-air type; 1=first vehicle in the type; A=first model in the series). The designations for later model blimps followed similarly.

[edit] Specifications (ZPG-2W)

[edit] General characteristics

Crew: 21
Volume: 28,648 cu m (1,011,000 cu ft)
Length: 105 m (343 ft)
Width: 23 m (76 ft)
Height: 32.6 m (107 ft)
Empty: kg ( lb)
Loaded: kg ( lb)
Powerplant: two, Wright R-1300-2 Cyclone 7 radial air-cooled engines, 597 kW (800 hp)