Airships (sometimes referred to as dirigibles, or more commonly, zeppelins) are an advanced type of aerostat, or lighter-than-air vehicle that utilizes rudders and propellers to provide maneuverability and thrust while airborne. They use large, internal ‘cells’ of lighter-than-air gas to stay aloft, typically helium; hydrogen was used in pre-WWII German zeppelins – only because of an American embargo on helium at the time – and was considered highly dangerous due to its flammability. Most modern airships are commonly powered by everything from solar panels (using nanotech embedded in the outer skin) and vent-style wind turbines, to thorium reactors (MSRs).
Inception and World War I (1900-1918)
The first successful flight of a rigid airship took place in Germany in 1900 with the flight of LZ 1, general and inventor Count von Zeppelin’s design, which became a major influence on all future airship construction (referred to as the zeppelin-type). For the duration of the First World War, Germany (in addition to France and Italy, but to a far greater extent) made heavy use of zeppelins as scouting and bombing craft, many of which were used to make raids on Britain (in a mildly eerie foreshadowing of the Battle of Britain over twenty years later). Zeppelin raids merely incurred further wrath from the already infuriated British, and utilizing a combination of searchlights and extensive anti-aircraft batteries, they forced the German crews to seek higher altitudes to avoid AA flak, thus reducing their already poor bombing accuracy. These early zeppelins proved that their presence on the frontlines of war was a virtual death sentence to their own crews, with over a dozen destroyed when confronted by superior Allied fighter craft, namely Britain’s famous Sopwith Camel. At war’s end, multiple surviving zeppelins were transferred to the Allies as reparations from Germany, namely to Britain, the United States, France, Italy, and Japan.
Interwar period; major advances (1919-1937)
The interwar period saw a massive increase in use of zeppelin-type airships, largely as commercial passenger transports for transatlantic and transcontinental flights, but also inaugurated a new era of military airship construction.
The US Navy also acquired an interest in rigid airships in the early ‘20s, building its first, the USS Shenandoah (ZR-1), in 1923, based on a German design from WWI. They also managed to acquire another two from overseas, the British-built USS Linton (ZR-2) in 1923, and the German-built USS Los Angeles (ZR-3) the following year. These early airships were primarily test beds, and any consequent failures on their part would benefit potential follow-ons in the future. Linton crashed into Lake Michigan in 1927 after a steering failure, and following a near-collision with a mooring mast at Columbus, OH, in 1925, Shenandoah received a major refit, where her control car was enlarged and mounted to the hull, two engines were removed; the remaining three replaced by more powerful ones, and an aircraft trapeze – capable of carrying a single aircraft – was mounted on the outer hull. She continued on in an advanced training capacity for another eight years before being scrapped in 1933. The Los Angeles was also fitted with aircraft and lengthened in the late-‘20s, becoming the Navy’s longest-serving and most accident-free airship until the late ‘60s.
Britain began her own civil airship program in the mid-1920s, labeled the Imperial Airship Scheme. The first two ships, R100 and R101, were completed in 1926, and made their maiden flights to Montreal in Canada and Karachi in what was then British India (now the Federal Republic of India), respectively, the next year. These ships were each of a different design, with R100 utilizing already existing technology, while R101 served as a test bed of sorts for a new airship design. Both served to influence a follow-on, the R102 – a lengthened version of R101, with a roughly 60% greater gas capacity – completed in 1929. The original pair was twice refitted, first in early 1930 – in which both were lengthened and converted to use helium lifting gas instead of hydrogen (utilized in all future airships, with the exception of pre-war Germany) – and again in 1935, when they were again lengthened and received far more powerful engines. The fourth, R103, was completed in 1932, to a further revised and lengthened design, while the fifth and final pre-war airship, R104, was completed to yet another larger, revised design in 1935. All five made regular trips to Montreal, Karachi, Calcutta, Darwin and Sydney in Australasia and Ismailia in Egypt for several years. With the outbreak of war in 1938, construction began on a series of large, heavily reinforced airdocks in Scotland’s Outer Hebrides, as shelters for the relatively fragile airships.
In 1928, the Zeppelin Company completed work on LZ-127, named Graf Zeppelin after Count von Zeppelin, for international and transoceanic passenger service. Two years later, the LZ-129, Hindenburg, was completed and immediately began transatlantic service to both North and South America. She was followed the next year by a sister craft, the LZ-130, Graf Zeppelin II, and in 1932 by the further-improved LZ-131, Bismarck. The four airships served very well in their intended roles and as Nazi propaganda in the late ‘30s, the latter reason of which being the only reason Luftwaffe chief Hermann Goring didn’t outright order their scrapping in favor of fighter aircraft construction. The first Graf Zeppelin, however, retired and already antiquated by the outbreak of war, was scrapped and recycled into aircraft parts.
A radical new design, the metal-skinned airship, was introduced in 1929 with the US Navy's ZMC-2 (Zeppelin Metal Clad, 200,000 sq. ft. gas capacity), built by the Aircraft Development Corporation of Detroit. Her skin was composed entirely of Alclad, a highly corrosion-resistant alloy of aluminum. ZMC-2 was the only all-metal clad airship ever built for the Navy. The second generation of Navy airships was inaugurated with the commissioning of USS Akron (ZRS-4) in October 1931. She introduced an innovative design feature common in future airships – an internal hangar initially capable of carrying up to four aircraft (F9C Sparrowhawks in the 1930s; F4F Wildcats and F6F Hellcats in WWII), with a fifth mounted on an external aircraft trapeze, a concept pioneered by the Shenandoah and Los Angeles. Under the command of Admiral William A. Moffett, a strong proponent of Navy airships, Akron participated in the Fleet Problem XIII (13) exercise off the West Coast in March 1932, and managed to prove her worth not only by providing valuable scouting information to her ‘team’ fleet, but also by using her F9Cs to perform a surprise ‘attack’ on an ‘enemy’ carrier - the Lake Erie (CV-4) - effectively ‘crippling’ her. Akron had, at long last, proven that not only could airships be useful reconnaissance platforms, but their aircraft could also be used in an effective manner against a potential enemy target, thus enabling her ‘team’ to win the exercise. Airships had proven their potential value to the higher-ups of the Navy, who ordered that a further four be constructed. On the heels of this success, she was followed a year later by a sister, Macon (ZRS-5), built to a lengthened design, thus considerably improving her range over Akron. That same year, the US Army inaugurated its own airship program, with their all-metal-clad airship, the ZMC-1-20, up to ten times larger than ZMC-2 - similar in size to the Navy's recently-scrapped Shenandoah. A further three Navy airships, San Remon, Evans, and Calixto, built to the modified Macon design, were constructed and commissioned between 1935 and 1937. In 1938, the Army again displayed its interest in airships, this time, with their all-metal clad rigid airship program, combining the best attributes of the joint ZMC program and the Navy's new ZRCV's into a unique design that never took with the Navy: the massive ZRMCV, 2 ½ times larger than the Akrons, and capable of carrying a variety of fighter and bomber aircraft, from up to 15 fighters, to 3 B-25 Mitchells, or a single B-17 Flying Fortress or B-24 Liberator.
Buoyed by the military’s success and the obvious safety of the German zeppelins as passenger ships (minus the hydrogen), air giant Pan Am ordered ten airships based on the modified Macon design for their Clipper service in late 1937. These new airships were for those who “...didn’t need to get anywhere fast, but simply get there, and in a nearly unparalleled lap of luxury.” Four were completed prior to US entry into WWII; the remaining six were put on hold until war’s end in 1946. The three remaining German airships, Graf Zeppelin II, Hindenburg, and Bismarck, were all laid up in the United States in their hangars at Lakehurst Airdock following the outbreak of war in Europe in 1938, and remained there for the duration, stripped of identifying marks, and their hydrogen cells emptied. Of Britain’s five pre-war commercial airships, R100 was laid up in the specially reinforced airdocks in the Outer Hebrides in early 1940, while R101 was sent to India to serve as a scout; R102 served in Malaya, and was present to attempt an evacuation of part of the Singapore garrison in February 1942, but was subsequently destroyed by Japanese Zeros. R103 played a major part in the North African Campaign (also called The Desert War) from 1940 to 1943 as an advance scouting and reconnaissance platform, while R104 served as a specially-modified hospital ship of sorts for the embattled Australian Army from 1939 to 1945.
Even as the final two airships of the Akron-class, Evans and Calixto, were being assembled, US Navy planners were already putting forth a new design, the ZRCV (airship aircraft carrier). It could carry up to twelve aircraft (eight were stored in an internal hangar, and two on a pair of modified retractable trapezes, which would effectively halve the launch time for such a large number of aircraft), had a helium capacity over 50% greater than that of the Akrons (10 million sq. ft. as opposed to 6.5 for the Akron) and up to a dozen .50 cal. heavy machine guns for AA defense. The first of the class, Pacifica (ZRCV-9), was completed and commissioned in the late spring of 1939, followed only months later by Norfolk (ZRCV-10).
By the late 1930s, the Navy came to the conclusion that, realistically, the aging Los Angeles would have to be replaced in the role of training airship. With this in mind, planners from the Navy’s Bureau of Aeronautics introduced a smaller, simplified version of the venerated Akron design: the Fort Wayne. Even though Los Angeles remained in commission, she was used in a very limited capacity, and the Fort Wayne (ZRT-1) took over the role as official training airship from the L.A. and moved her base of operations to the West Coast upon commissioning in 1940. A second ship, the Fort McHenry (ZRT-2), completed almost exactly one year after the Fort Wayne, operated out of Lakehurst for the duration of the war as the official training airship for the Atlantic; the third, Fort Cumberland (ZRT-3) – completed in 1943 – operated out of Hawaii. Navy airship crews often referred to them as ‘the Forts-class’ (for obvious reasons).
World War II; the airship is re-proven (1938-1945)
Four more ZRCV’s were completed by the fall of 1941, but with the attack on Pearl Harbor, the program almost literally changed overnight. Various projects deemed non-critical to the infant war effort were drastically curtailed or cancelled altogether, including the final two airships of the ZRCV program; they were each about 30% complete when their duraluminum hulls were scrapped and recycled for use in the aircraft industry – in a similar fashion to Nazi Germany’s first Graf Zeppelin three years prior. Neither were assigned names and only had the provisional designations of ZRCV-15 and 16, respectively. (The hull numbers were later reused and applied to a pair of Cold War-era airships).
With the official outbreak of war, all US Navy airships had their antiquated Curtiss F9C Sparrowhawk biplanes replaced with Grumman F4F Wildcats, most of which were carried for the duration of the war. In the two years prior to Pearl Harbor, the five ships of the Akron class had each made at least one transatlantic crossing to Britain, transporting – over time – thousands of tons of goods to the beleaguered island nation. The crew of Calixto (ZRS-8) was distant witness to the destruction of the British Royal Navy battlecruiser HMS Howe in the Battle of the Denmark Strait on May 24, 1941, while returning from a cargo drop at the Outer Hebrides airdocks. Multiple photographs were taken by Calixto’s crew, most notably “Flashes to the Northeast, in the Denmark Strait – 5-24-1941” and “Smoke/Explosion column over the Denmark Strait – 5-24-1941.” It wasn’t until almost two days later that the crew learned the significance of their observations, while in airdock at Kujalleq Air Base. They held a memorial service for the men of Howe on May 27 and erected a temporary shrine on the eastern perimeter of the base (it was made a permanent and official memorial in 1955).
By the early 1942 timeframe, all but one of the ZRCV’s – San Quentin (ZRCV-11) – were operating off the US Eastern Seaboard as part of a slowly growing network of anti-submarine warfare (ASW) operations against German U-boats. They operated from bases in the Bahamas, Bermuda, St. John and Ft. Cumberland in Maine, Halifax and Breton in Nova Scotia, St. John’s in Newfoundland, and Kujalleq Air Base in southern Greenland. These airships formed the core of the Atlantic Naval Airship Fleet (ANAF), a major component of the US Navy’s regional ASW operations. As U-boat attacks became bolder with each passing month, and with much of the US surface fleet occupied in the Pacific, the Air Fleet had its job cut out rather clearly. As American industry rushed to adapt to wartime standards, the ANAF filled a critical niche, providing the occasional escort for Britain-bound convoys and patrolling the US East Coast, on the hunt for prowling U-boats. On the Pacific side of the war, the ZRCV San Quentin and three of the Akrons – Akron, Macon, and San Gabriel – served to heavily augment the ASW forces on the West Coast as the core ships of the Pacific Naval Airship Fleet (PNAF), fending off and sinking a half-dozen or more Japanese submarines throughout the war.
By late 1942/early 1943, American shipyards were turning out destroyers and destroyer escorts like clockwork, many of which were immediately devoted to transatlantic convoy and ASW duty. But even with the now-greater availability of escort ships, the ANAF still retained its highly-valued position as a patrol and escort force, at which time the naval airship again proved itself, and in a rather unexpected way: the airships’ duraluminum construction would usually present itself as a significant anomaly to enemy radar operators, who, more often than not, would mistake it as a kind of lightning storm or other natural phenomenon. This worked quite significantly in the favor of the American airship crews and their fighter pilots when hunting U-boats in the Atlantic (and on occasion, Japanese I-boats in the Pacific), being able to launch an attack and sink an enemy submarine with little to no warning proved a great tactical advantage. The product of the Army's ZRMCV program, which had produced upwards of thirty craft before the start of the war, saw service in the skies of Europe, North Africa, and the Atlantic, launching medium and heavy bombers against German positions and infrastructure on land, and occasionally joining their Navy counterparts for ASW operations in the Atlantic.
The few times a U-boat was able to actually attack an American airship, the damage incurred against the main body of the craft even by shells from the subs' deck guns was minimal, due in large part to the sheer size of the ZRCVs and their internal spaces; the control car and engines on the other hand, fared much worse. While on patrol over Scotia Bay on October 18, 1944, the Norfolk was engaged by submarine U-768 in a nighttime sneak attack sixty-one miles southwest of St. John, Maine. Firing a series of flares that illuminated the giant airship plain as day, automatic fire from the sub's AA gun damaged the control car, while the deck gun destroyed one of her port engine pods. After dropping its own flares to illuminate the marauding U-boat, responding .50 cal. fire from the airship silenced the submarine's guns, while one of her Hellcat pilots launched at less than forty feet off the water, skimming the wavetops to deliver a killing blow that sent U-768 to the bottom of Scotia Bay. Norfolk moored at the St. John Airdock (which is today in civilian use) the next morning for 'patch-up work' before heading east to Halifax for full repairs. She returned to service just over a month later.