Several U.S. government agencies— among them the Navy, Army, Air Force, Coast Guard, and Defense Advanced Research Projects Agency—are looking into new roles and designs for lighter-than-air (LTA) aircraft, or “blimps” in the vernacular. The craft under consideration include some huge vehicles that would be far larger than the Navy’s last blimps, which were also the world’s largest non-rigid airships (i.e., they did not have a rigid frame encasing their gas bags, as did the German Zeppelins of World War I).
The U.S. Navy was in the blimp business from 1917 until 1962, when the last ZPG-3W was taken out of service. In that period a total of 241 blimps was acquired, including 21 from allies; in addition, the Navy operated four large, rigid airships during the 1920s and 1930s. The Navy’s blimp strength peaked at 168 during World War II, operated and supported by 12,400 personnel. These “gas bags” were employed mainly in the convoy escort role. Their contribution was small when one considers the massive investment to build and operate them, and the cost and handling of the helium that kept them aloft, in comparison to their accomplishments. Blimps rarely sighted U-boats, sank none, and one, the K-74, was shot down by the submarine U-134 in July 1943.
After the war the blimp force was rapidly reduced. Still, a peak postwar force of 44 blimps was operational in mid-1957, both war-built K-class airships and newer craft. Blimp development continued after World War II, and the construction of several series was initiated. All were larger than the wartime K-class, with more endurance and more lift capability.
Initially these new blimps were developed for ocean escort/antisubmarine operations, with first deliveries in 1951. A total of 56 were built after World War II (See table). These blimps were designated by the letters Z, indicating LTA; P, indicating patrol; and N for non-rigid. The last letter was changed to K for Goodyear in 1947 and to G in 1954, that firm having produced all postwar Navy blimps.
The prototype ZPN-l/ZPG-1 was followed by 12 similar production blimps designated ZP2N-1/ZPG-2. These were followed by five similar craft configured for airborne early warning (AEW) and given the suffix letter W. These were fitted with the ubiquitous AN/APS-20B or E air search radar and the AN/APS-62 height-finding radar, as well as an extensive electronic countermeasures suite. The radar antennas were fitted to the gas bag with the APS-62 dome projecting from the top of the blimp, looking like a small dorsal fin.
The AEW role took on new importance in the mid-1950s as the United States was building a radar barrier to detect Soviet bomber attacks on the country. This radar barrier included fixed sites in Canada, radar platforms off the Atlantic coast, Navy radar picket ships, and Navy-Air Force radar picket aircraft.
In an evaluation of the on-station capability of blimps, in May 1954 a ZPG- 2 under Commander Marion Eppes departed Naval Air Station (NAS) Lakehurst, New Jersey, flying north to Nova Scotia, south to Bermuda and then the Bahamas, across the Caribbean Sea and Gulf of Mexico, and landed at NAS Key West, Florida. The blimp was airborne for 200 hours. More endurance trials followed, demonstrating the all- weather as well as endurance capabilities of modern blimps.
Another ZPG-2, flown by Commander Jack R. Hunt, in March 1957, established a new blimp record—flying from NAS South Weymouth, Massachusetts, across the Atlantic to Portugal, then to North Africa, and back across the Atlantic to Key West. The flight set a long-distance record of 9,448 nautical miles in 264 hours aloft. Other test flights took Navy blimps across the Arctic Circle.
Meanwhile, the first five AEW blimps were followed by the ZPG-3W series, the first of which lifted off in July 1958. Similar to the previous models, the new blimps were larger and had higher-powered engines. Indeed, the ZPG-3Ws were the largest non-rigid airships ever produced, with a volume of more than 1.5 million cubic feet and a length of 403 feet.1
Its twin engines were Wright R-1820- 88 Cyclone 9 radials, each rated at 1,525 horsepower.
The ZPG-3W had a maximum speed of 82 knots in still air, was credited with a range of 2,800 nautical miles, and a flight endurance of 80 hours. Interestingly, the earlier and smaller ZPN- 1/ZPG-l exceeded the later blimp in terms of rated endurance (88 hours) and range (3,400 nautical miles).
Goodyear initiated series production of the ZPG-3W, but in the event only four of the design were built, the last accepted by the Navy on 30 March 1960. She was the last manned airship to be built for the U.S. Navy. (A short time later, on 6 July 1960, one of the ZPG-3W blimps plunged into the Atlantic Ocean some 30 miles southwest of Lakehurst; only three of the 21-man crew survived.)
Despite the demonstrated endurance of these airships and their effectiveness in the AEW role, the blimp force was being reduced. Eleven blimps were operational in October 1960, when Vice Admiral Robert B. Pirie, the deputy chief of Naval Operations for Air stated that “if budgetary limitations the Navy has experienced in the last three or four years continue we won’t be able to replace those blimps we now have.” Pirie said that anything a blimp can do can be done “at the moment by a plane more effectively and cheaper.”2 Design efforts for more advanced blimps were immediately halted.
The end of Navy LTA came sooner than most people expected. On 21 June 1961, Secretary of the Navy John B. Connally announced that the Navy’s LTA program would be terminated in the near future. The last airship units, Airship Patrol Squadrons (ZP)-1 and -3, and Fleet Airship Wing 1 were disestablished on 31 October 1961.3 The last flight of a U.S. Navy airship—a ZPG-3W—occurred on 31 August 1962.
In the same period the Navy’s future seaplane program and the Regulus missile program were also terminated. All were primarily victims of budgetary constraints, in part caused by the acceleration of the Polaris fleet ballistic missile program.
Post-World War II Blimps |
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Designation |
Post-1954 designation |
First flight |
Number built |
ZPN-1 |
ZPG-1 |
1951 |
1 |
ZP2N-1 |
ZPG-2 |
1953 |
12 |
ZP2N-1W |
ZPG-2W |
1954 |
5 |
ZP4K-1 |
ZSG-4 |
1953 |
15 |
ZP5K-1 |
ZS2G-1 |
1954 |
4 |
ZPG3-2 |
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1. By comparison, the largest U.S. Navy rigid airship, the Macon (ZRS-5), commissioned in 1933, had a volume of 6.5 million cubic feet with a length of 785 feet. She could carry, launch, and recover four scout-fighter aircraft.
2. N. Polmar, “Blimps Seen On Way Out,” Navy Times, 29 October 1960, p. 1.
3. Earlier in 1961 Airship Airborne Early Warning Squadron (ZW) 1 was changed to ZP-1.