Goodyear ZPN / ZPG / ZP2N / ‘N’ Class

With the end of WW II, the U.S. Navy's airship service was reduced in size, but new types were developed by Goodyear and brought into service with the Navy. First of these was the N-Class of 875,000 cu.ft. flown in prototype form on June 18, 1951. Preliminary ground and flight tests for the prototype were disappointing, mandating furter evaluation to explore improvements. The Board of Inspection and Survey trials for N-1 persisted into 1953.

Under the post-war naval airship designation system NA became ZPN-1, and with a further change in 1954 became ZPG-1. This greatly improved, long-range patrol ship was 334ft long and powered by, two 800 h.p. Wright Cyclone 7 engines mounted inside the car. A crew of 14 was carried in the double-decked car which gave much improved messing and sleeping arrangements compared with those of the wartime ships. One of the most notable external features of the design was the angled position of the tail surfaces, so arranged to, help keep the overall height of the ship (96ft) within the limits of existing sheds. Only one example of this type was built, (GZ-9) but it served as the basis of the later ZPG-2 and ZPG-3 ships.

After extensive evaluation trials with the prototype ZPN-1, an improved and slightly larger version, the ZP2N4, was completed and flown on March 20, 1953. This type was put into production in two forms known as the ZPG-2 patrol version and the ZPG-2W Airborne Early Warning version. The ZPG-2 of 975,000 cu.ft. was powered by two 800 h.p. Wright Cyclone 7 engines driving Curtiss Electric three-blade, variable-pitch, reversible propellers on out-riggers projecting from each side of the car.

The control car accommodated the fourteen crew on two decks, with all operational stations on the lower deck and crew's quarters on the upper deck. All control surfaces were operated by a single control column, duplicated for the pilot and co-pilot; a major departure from the previous normal airship practice of separated elevator andrudder control wheels. The ship was also equipped with an autopilot which was of immense value in reducing crew fatigue on patrols lasting two or more days.

Twelve were 12 built 1953-1955 and were in service to 1961.

The ZPG-2W version was essentially the same except that it carried large quantities of sensitive, long-range, radar equipment for aircraft detection, and a large radome on top of the envelope. This could be reached from the control car by way of a 75ft vertical tunnel inside the envelope. The, ZPG-2s made many long flights, setting up World endurance records in May, 1954, of 200.4 hours continuous flight, and in March, 1957, of 264.2 hours (11 days), both flights without refuelling. The second flight took the airship from its base at Weymouth, Mass., to Key West, Florida, by way of Portugal and North Africa, 8,216 miles in all.

Five were built 1957-1958 and were in service to 1961.

As a further development of the ZPG type, the ZPG-3W appeared in July, 1958. The largest non-rigid airship ever built, it was 404ft long with an envelope capacity of 112 million cubic feet. Power was provided by two specially developed Wright Cyclone 9 engines of 1,525 h.p., driving 18ft diameter propellers. Twenty-four crew were carried in a car 83ft long, with extensive crew quarters on the upper deck. The envelope itself served as a radome for a 40ft internally-mounted radar antenna which rotated within the helium gas. Four were built 1958-1960.

Total post-war naval airship production accounted for 55 of the 200 new airships built by Goodyear between December 1939, and July 1963. The last for the U.S. Navy was a ZPG3W delivered on April 4, 1960. At that time the Navy still had 27 airships in commission. However, changes in naval policy and the need for budget savings in the light of the costly new Polaris submarine programme, forced a re-think of naval air requirements. On June 26, 1961, the Navy announced that the airship service was to be closed down, a decision which took effect during the following year.

Thirteen naval airships were deflated and placed in long-term storage in case of future need, while two ZPG-2s were retained for experimental work with the Airship Test and Development Department at Lakehurst. In addition, one ZS2GA was made available to Mississippi State University for a programme of boundary layer control research on airship envelopes. When these ships, too, were deflated at the end of 1962, forty-five years of U.S. Naval airship operations came to an end.

The last Goodyear airship for the American Navy was the ZPG-3W of 1958, the largest non-rigid ever built. A 40ft radar antenna rotated inside the envelope. These served until the closure of the airship service in 1962.

Goodyear ZPN

ZPG-1 (GZ-9)
Volume: 875,000 cu ft.
Length: 324ft.
Max Dia: 74ft.
Engines: 2 x 800 h.p. Wright R-1300-3A Cyclone 7.

ZPG-2 (GZ-11)
Volume: 975,000 cu ft.
Length: 343ft.
Max Dia: 76ft.
Engines: 2 x 800 h.p. Wright R-1300-3A Cyclone 7.

ZPG-2W (GZ-14)
Volume: 975,000 cu ft.
Length: 343ft.
Max Dia: 76ft.
Engines: 2 x 800 h.p. Wright R-1300-3A Cyclone 7.

Type GZ-17 (Navy ZPG-3W) 1958
Engines: 2 x  1,525 h.p. Wright R-1820-88 Cyclone 9.
Length: 403ft 6in.
Maximum Diameter: 85ft.
Volume: 1,465,000 cu ft (before stretch).
Maximum Speed: 90 m.p.h.
Cruising Speed: 50-60 m.p.h.
Maximum rate of climb: 2,400ft/min.
Range: in excess of 5,000 miles.
Endurance: 80 hours plus.
Fuel: 4,375 gallons.
Maximum Gross Weight: 93,496 lb.
Empty Weight: 71,130 lb.
Useful Load: 22,366 lb (including dynamic lift).

ZPG-3W (GZ-17)
Volume: 1,490,000 cu ft.
Length: 404ft.
Max Dia: 85ft.
Engines: 2 x l,525 h.p. Wright R-1820-88 Cyclone 9.

ZPN-1
Volume: 875,000 cu. ft.
Length: 324.4 ft.
Engines: two 800 h.p. Wright R1300
Top speed: 85 m.p.h.

ZPG-2
Volume: 975,000 cu. ft