U. S. Navy Lighter-Than-Air (LTA):
The Post-War and Cold War Era
Following the late 1945 return of Mediterranean minehunters ZP-14
, the US Navy LTA organization rapidly decreased. From more than 125 airships in 15 squadrons patrolling roughly 3 million square miles off the coasts of 4 continents, by the end of 1946 there were only 2 squadrons remaining. Airship Squadron 31 (ZP-31) based at NAS Santa Ana, CA was designated ZP-1 and maintained a small detachment at NAS Moffett Field.
Subsequently, by August, 1947 squadron ZP-1 was transferred to NAF Weeksville, NC, thus ending all LTA operations on the west coast. Airship Squadron 12 (ZP-12) stationed at NAS Lakehurst, NJ became ZP-2 with a detachment at NAS Key West, FL. Their four M-type airships of 650,000 cubic feet had operational flight endurance of over 100 hours, and M-1 had carried an airplane. They were 287 feet long and 85.1 feet in diameter. (K’s were 250 x 63.5.) Enlarged to 675,000 cubic feet, XM-1 set a 170-hour record flight in 1946.
By 1948 the Navy showed renewed interest in the unique and long range capabilities of airships, issuing a call for heavier-than-air (HTA) aviators to transition to LTA operations. Eighteen officers reported for duty to the Airship Training Unit (ZTU) at NAS Lakehurst. The venerable K-type airship was upgraded to “2K” with improvements such as electric propellers with reversible pitch, in-flight refueling, more sophisticated ASW radar, magnetic detection equipment, sonar capability, and equipment allowing communication between surface vessels and other aircraft Envelopes exceeded half a million cubic feet to lift the new electronics and their generators as effectiveness was greatly enhanced.
Fleet Airship Wing 1 was re-commissioned in January, 1949 for administrative and operational control of ZP-1, ZP-2, and ZX -11. In September, 1950, ZP-3 was commissioned at Lakehurst and ZP-4 was commissioned at Weeksville 8 months later. The entirely new “4K” (ZSG-4) airship, outwardly similar to the WWII K-types, incorporated previous upgrades and added new capabilities under a 525,000 ft3 envelope. ASW exercises repeatedly defeated Guppy-class submarines.
Increased capability was designed into the revolutionary ZS2G-1 (above), lifted by a 650,000 cu ft3 Dacron envelope featuring inverted “Y” control surfaces. Its longer car interior’s port side avionics suite mounted advanced ASW gear, and it carried the largest homing torpedo. An oversize sonar-fish towing winch mounted aft was also used for re-arming and re-manning. ZS2G-1’s landing gear was designed for steel carrier decks, but replenishment could be taken from most any fleet unit. Its high-tech features proved unreliable, but one ZS2G-1 airship was retained into 1961 as the “Flying Wind Tunnel,” investigating low speed aerodynamics.
A separate design team created the “Nan” ship. Prototype N-1 featured engines located inside the car, connected by transmission box to the propellers. This feature not only eased in-flight maintenance, but also allowed for efficient one engine - two propeller operation below 40 knots. Living quarters were provided for the crew on an upper deck. The production ZPG-2 (above) boasted a length of 343 ft., 75.4 ft. diameter for capacity of 975,000 ft3 with “X” tail and control surfaces. Tricycle landing gear could be electrically controlled, with the nose gear being raised 40 degrees to allow for mast mounted movement. No longer needing a flattop carrier, the ZPG-2 refueled from fleet oilers. It carried its own relief crew, which enjoyed berths and galley in the car’s upper deck. One ZPG-2 quickly broke the M-ship endurance record, remaining aloft for 200 hours. Another flew above the Arctic Circle, taking supplies to a remote ice station. In the spring of 1960 “Operation Whole Gale” tested ZPG-2s to maintain an ASW barrier 24/7 over two months in some of the worst winter weather in years, sometimes grounding all HTA. No sub got through as the exercise logged ever longer endurances; one ZPG-2 held ASW station for 95.5 hours, a record that compares favorably with today’s ASW airplanes. In a demonstration one ZPG-2 departed from NAS S. Weymouth and flew to Europe, setting a record of 8,216 miles in 264 hrs.14 mins. when it landed at NAS Key West. (Breaking the 1929 rigid Graf Zeppelin’s record, it’s a time-distance mark that stands to this day.) Nonetheless three squadrons were decommissioned, leaving FAW-1 with only ZP-3 and Airship Early Warning Squadron 1 (ZW-1) at Lakehurst, as other stations were mothballed. In 1956 adding additional radar created the ZPG-2W, becoming the core of Airship Airborne Early Warning Squadron 1 (ZW-1). The ZPG-2W sported a height-finder radar located on top of the envelope, accessible through a ladder-equipped access shaft inside. In the final -2W, a low frequency radar antenna, 33 ft. wide and 8 ft. tall, was installed inside the envelope.
In 1958 the US Navy took delivery of the ZPG-3W (right), the largest non-rigid airship ever constructed, specifically designed for AEW. It was 403 ft. long, 85.1 ft. dia. and, depending on envelope material, had a volume of 1,509,000 to 1,544,000 cu ft3. A 40 ft. wide radar antenna rotated in the envelope with the height finder radar dome mounted on top. The four ZPG-3Ws delivered to ZW-1 at NAS Lakehurst were part of the US Airborne Early Defense system. Their on-station endurance capabilities compared favorably to five USAF Super Constellations in rotation. Any unit could drop a floating bag of fuel for -3W retrieval on station. When filling in for ground based stations operators noted increased sighting capability. Seen as incompatible with the carrier-based Navy, on 31 October 1961, ZW-1 was decommissioned, along with ZP-3 and FAW-1. Following a short period of “Flying Wind Tunnel” experimental flights, the Navy ended 46 years’ LTA involvement.
Later experiments and prototypes finally found the Navy purchasing a new airship in 2007. The MZ-3A returns the USN to LTA research and development and airborne early warning (AEW), even assisting the Coast Guard in the 2010 Gulf oil spill. LTA’s future is bright.