[thread=118973]Discussion thread[/thread]
An alternate history, based on primarily several PoDs in which the airships Akron, Macon, and Hindenburg were not lost in accidents.
A Short History of the United States Naval Airship Service in the Second World War 1941-1945.
Introduction
In view of the tremendous value of the Navy’s rigid airships during the 1941-45 Battle of the Atlantic, it is instructive to realize that, during several periods in the 1920’s and 1930’s, the entire program came very close to being eliminated. For at least the first fifteen years of their service in the US Navy, rigid airships were considered by all but a few advocates as unnecessary and ineffective experiments forced upon the fleet by a few important senior commanders and influential members of Congress representing districts which stood to benefit by the development of an airship industry in the United States.
From the beginning, both traditional “battleship admirals” and the new naval “airpower advocates” had little use for the zeppelin airship. In an environment of limited funding, traditionalists considered airships unproven competitors with light cruisers, submarines, and other surface combatants with clear offensive capabilities. Air power advocates, on the other hand, saw airships as directly competing for scarce aviation funds with flying boats and aircraft carriers. Since only military mission the zeppelin was believed suitable for was unarmed scouting and reconnaissance, and even this had not been proven, most navy officials were unhappy to sacrifice either surface ships or airplanes to build rigid airships.
In fact, early US experience with rigid airships tended to support this pessimism. Both ZR-1, USS Shenandoah, and ZR-2, the unnamed British R-38, were destroyed in crashes before either ship had a chance to demonstrate any military value. Their loss reinforced the impression among the US public and many naval personnel that zeppelin airships were fragile craft, excessively vulnerable to weather conditions and inherently unsound. Lost in these accusations was the fact that neither ZR-1 (a copy of a 1916-vintage German naval zeppelin), and ZR-2 (based on the very lightly-built German “height-climbers, and widely believed to be a particularly faulty design) were not designed for North American weather conditions or rigorous low-altitude fleet scouting operations. Even the highly successful ZR-3, USS Los Angeles, did very little to advance the cause of the rigid airship in the US Navy. Because ZR-3 was a new airship built by the Zeppelin Company as war reparations (to replace German naval zeppelins destroyed by their crews after the armistice), Britain and France insisted that the ship be built as a non-military vessel and not operated as a part of the fleet. Thus, while the ship served well to train crews and “show the flag” across the country for over 10 years, it had little opportunity to demonstrate any value to key decision makers in the Navy Department.
Several factors began to change this situation. Individually, they may not have had much effect, but taken together they ensured the survival and eventual success of the rigid airship in the navy.
The Goodyear-Zeppelin Corporation was founded in 1923, as a joint venture of Goodyear Tire and Rubber Corporation, of Akron, Ohio, and the Zeppelin Company in Germany. This provided US airship designers with full access to all Zeppelin patents and trained design staff. Following in the early 1930’s, Goodyear-Zeppelin as well as the German Zeppelin Company proposed a number of subsidiary commercial airlines to operate trans-Atlantic and trans-Pacific passenger and mail service in Goodyear-Zeppelin built airships.
In 1928, following strong lobbying efforts from the Goodyear-Zeppelin Corporation, and as recommended by the United States Maritime Commission (USMC) and National Advisory Committee on Aeronautics (NACA), the United States Congress passed “An Act for the Establishment of a Commercial Airship Transportation Industry in the United States”, commonly referred to as “the Airship Act”. While this act initially provided no direct funding for the construction of airships or related industries, it set US policy to establish Goodyear-Zeppelin’s airship airlines as the official US passenger and mail carriers in any future trans-Atlantic or trans-Pacific airborne commerce, provided for all commercial airships to be constructed to US Navy specifications and crewed by naval reservists, and require all civil airships and facilities liable for nationalization as naval auxiliaries in the event of war or national emergency.
In 1934, as an important element of the New Deal public works recovery measures implemented by Franklin Roosevelt, the Airship Act was amended to provide funding for several large airship-related construction projects. This included three new airship building sheds at the original Goodyear-Zeppelin Air Dock in Ohio; and four combined building sheds/hangars to be wholly operated by the Navy, two each at existing naval air stations (Sunnyvale, California; and Lakehurst, New Jersey). In subsequent years, the Act was amended further to provide additional Works Progress Association (WPA) funding to build up to eight “civilian” airships similar in basic design to the Navy’s ZRS-4 (USS Akron) type airship, with passenger spaces occupying areas used as airplane hangers in the naval ships. WPA funds were also used to build other infrastructure supporting the commercial airship industry, including helium extraction plants, duralumin fabrication factories, hangers, and passenger/freight handling facilities. Also under the amended Airship Act, NACA established the Merchant Airship Academy near San Diego, California, to provide training to civil (and potential naval) aircrew and air dock workers.
A vision of the future – the ZRS class ships
Despite these positive developments in the civil arena, the role of the rigid airship in the US Navy remained uncertain through the early 1930’s. Goodyear-Zeppelin’s first rigid airship, ZRS-4, USS Akron, entered service in early 1931. A key improvement in this ship and its successors was the provision of an internal hangar capable of handling and servicing five small Curtiss F9C fighter planes. In early training exercises, Akron was operated very conservatively and made little use of little use of its airplanes. Employing tactics more suited to the German Navy in 1916, Akron’s commanders tended to use the airship itself as the scout, only launching planes after contact was made. As they soon discovered, attempting to locate and stealthily track surface ships in a gigantic sliver object flying at only several thousand feet was virtually impossible. In fleet exercises, Akron was often seen and “shot down” by surface ships or ship launched floatplanes before she herself saw the ships. As her crew became more experienced with their ship, Akron began to use her airplanes more as primary scouts, but in two years flying, the ship had not demonstrated any real value to the fleet.
Akron’s sister ship, ZRS-5, USS Macon, entered service in 1933, and at that point things began to improve. Prior to this, all failings of the Akron in fleet exercises were automatically interpreted as a basic failing of the airship as a type, not as a possible product of poor crew performance. With two ships at its disposal, the Navy could now compare the performance of these ships and better understand how and why they performed as they did. Also, as would be expected, there was a natural evolution in the effectiveness of their commanders and crews as they learned from each other and became more experienced with the unique abilities and drawbacks of these giant ships.
By mid-1935, most senior officers accepted Akron and Macon as useful, if not exceptionally valuable, adjuncts of the fleet. The ships’ commanders had developed effective operational doctrine focusing on the use of the ships’ F9C fighters to greatly extend the effectiveness of the airships as strategic scouts, and their crews were both well trained and experienced. In the six “Deep Pacific” fleet problems undertaken in late 1935, the airships proved themselves very effective long range scouts, frequently locating and identifying “enemy” forces well in advance of other scouting vessels or carrier-launched scout planes. Although they often found themselves “shot down” as the problems evolved and the operational areas became more congested, this usually occurred well after they had provided information judged sufficiently important to justify their loss. Nonetheless, there was very little interest in investing additional funds for large and expensive units which lacked any offensive capability of their own. It appeared Akron and Macon would remain the only fleet airships in the US Navy for the foreseeable future.
The Turning Point – Fleet Problem XIII
A key event transforming the Navy’s grudging acceptance of airships to advocacy was Fleet Problem XIII in December, 1935. This featured a simulated “Yellow” attack on a “Blue” base in the Panama Canal Zone. Yellow, based at Pearl Harbor, was tasked with mounting successful airstrikes and shore bombardment of Blue’s base, preparatory to a hypothetical invasion, and was provided a powerful strike force centered on both main fleet carriers (USS Lexington and USS Saratoga) supported by the battleships USS Colorado, USS West Virginia, USS Tennessee, and USS New Mexico, and a mixed screening force of light cruisers, destroyers, and submarines. Blue was deliberately provided a much smaller defensive force comprising only two older battleships (the USS Wyoming and USS Arkansas), the old carrier USS Langley, two heavy cruisers, a few submarines, shore-based flying boats, coastal aviation, and the Akron and Macon. Although the problem was designed primarily to evaluate evolving doctrine regarding the use of aircraft carriers, it was also an ideal situation for the two rigid airships to demonstrate their unique and unmatched capabilities as high speed, high endurance, long range aerial scouts. This, along with a combination of ideal weather conditions for airship scouting and poor decisions by Yellow” fleet commanders, ensured their outstanding and unexpected success.
Operating together under the overall command of Admiral William Moffett, and assisted by an unusual northwesterly tailwind, Akron and Macon moved at extremely high speed toward the Yellow fleet’s project approach route. Very early in the exercise, Macon’s scout planes were able to locate the advance scouting screen for the Yellow force in the open Pacific over 1500 miles from the Canal Zone and report the location and heading to the “Blue” main force. Making excellent use of their scout planes and employing the low cloud cover to maximum effect, the airships were able to swing round the advancing enemy and take up station behind the main Yellow force of battleships and carriers, just outside of visual range. Although Moffett expected his airships would eventually be located and “destroyed” by Yellow’s carrier planes, they remained undetected throughout most of the problem, providing valuable coded information from their F9C scout planes to Blue’s main force.
On the other hand, the Yellow force, under the overall command of Admiral William Halsey, made far less than effective use of its scouting assets. Although radio signals from the airships gave Halsey with a general idea of their relative bearing, he inexplicably made no serious effort to find and “destroy” them, claiming in his debriefing that he was worried his own scout plains might actually collide with them in the low clouds. In other respects, Yellow aerial reconnaissance was unexpectedly poor.
Presuming inaccurately that the weak main Blue force would seek to engage near the Canal Zone under the protection of its land-based aircraft and shore batteries, the Yellow force continued to push ahead toward Panama at high speed. In fact, Blue Force commander Admiral Ernest King adopted the exact opposite strategy. Knowing that Halsey ultimately needed to enter Panamanian waters in range of Blue’s powerful land based air assets, King hoped to attack and eliminate one or both of Yellow’s carriers early in the exercise. This would deprive Halsey of the air support he needed for a successful strike.
Toward the end of the second day of the problem, information provided by the airships allowed the Blue submarine USS Cuttlefish to infiltrate the Yellow screen and “torpedo” USS Lexington, the referee on board the aircraft carrier ruling her “severely damaged” and requiring her to return to Hawaii. Believing that the small Blue fleet would not risk dividing their forces intercept the carrier in its way back to Hawaii, Halsey detailed only two destroyers to escort her.
Guided by information from Akron and Macon King was able to swing out of the way of the Yellow scout screen. Thus, by 0400 on the 3rd day of the exercise, the main Blue force consisting of the carrier USS Langley and the heavy surface units had reached a position less than 150 miles northeast of the Yellow main force. At 0700, the Langley launched its small strike force, which achieved complete surprise. Referees judged the Saratoga’s flight deck irreparably damaged, making her unable to operate aircraft for the remainder of the problem. They also ruled all of Langley’s attacking aircraft lost in the action, but by then the damage was done. In two separate actions made possible by reconnaissance from Akron and Macon, Yellow had lost all of its offensive and defensive air support. Halsey recognized that, in a real combat situation, any attempt to proceed with close-in shore bombardment without air cover could be disastrous. He then sought instead to bring the Blue force containing the Langley into a surface action against his overwhelming force of battleships. Unfortunately, he was unable to locate the Blue ships, and they succeeded in slipping away.
By then, the two Blue airships had divided up, Akron continuing to shadow the main Blue force, with Macon tailing the “crippled” Lexington en route to Hawaii. Since the aircraft carrier had been ruled to be “heavily listing“ after the Cuttlefish’s “torpedo hits” it was not permitted to operate its aircraft, making it essentially a blind sitting duck. Knowing this, Admiral Moffett on the Macon prevailed on the referees to adjust the rules of the problem to presume that, in an actual wartime situation, he would have a small number of 100lb bombs on board which could be changed out for the F9Cs’ external fuel tanks.
As required by the referees, Macon’s HTA unit simulated the “bombing up” of their aircraft by removing and then replacing the fuel tanks on three fighters currently in the hangar being refueled, and less than 2 hours after Moffett received approval from the judges, they were launched. The three planes soon arrived over the “crippled” carrier and made a perfect low angle bombing run across the length of the flight deck. To add insult to injury, the F9C pilots dropped toilet paper rolls as they flew by, all of them hitting the ship’s deck. Faced with such evidence, the referee on Lexington ruled the attack successful. Although the Lexington was not “sunk”, the referee did rule that the attack started fires which resulted in the lost of many aircraft and personnel. In exchange, the three F9Cs were ruled “shot down” by Lexington’s anti-aircraft batteries and escorting destroyers. However, Macon’s attack showed that, in the right situations, aircraft carrying rigid airships could be effective offensive weapons.
As a result of Fleet Problem XIII, the rigid airship went from being considered a tolerated curiosity to a valuable element of the Navy. All of the plans and designs which had been languishing for years at the Navy’s Bureau of Aeronautics (BuAer) Lighter-than-Air section now had a real chance of seeing fruition.
The Prewar Buildup, 1936-1941
The Navy received authorization to procure two more ZRS type ships in the 1936 naval appropriations. The first ship was already well under construction at the Goodyear-Zeppelin Air Dock as the first commercial ship authorized under the amended Airship Act. She was based broadly on the Akron design, but with her hangar bay replaced by internal accommodations for 70 passengers, appropriate commercial staff, freight, and mail. Following a redesign to restore the airplane hangar and bring all other elements of her design to operational naval standards, she entered service as ZRS-6, USS Wichita, in early 1937.
ZRS-7, USS Newark, was designed and built from the keel up as a naval airship and entered service in early 1938. Newark was built to a significantly revised design proposed by the Navy’s Bureau of Aeronautics (BuAer), This replaced the internal airplane hangar and its single trapeze and trolly system for moving planes around with a strengthened keel mounting six individual launching stations and trapezes in tandem along the bottom of the ship for its F9C fighters. Although the planes’ partially exposed condition restricted the ability of the HTA unit to perform extensive maintenance procedures on them, the individual launching stations promised much quicker launching and retrieval operations. This system soon proved itself very efficient and, after USS Newark, no further naval airships were built with internal hangars.
Following completion of the ZRS-7, the ZRCV type ships were introduced. Intended as aerial aircraft carriers with an offensive capability, these became the largest operational airships ever built, being over 900 feet long and containing a volume of over 10,000,000 cubic feet of helium gas. The ships carried trapezes and launching/retrieval stations for up to 10 hook-on aircraft.
In the 1938 naval appropriations bill, funding was authorized for 10 ZRCV ships to be completed over the following four years. The first two, ZRCV-1, USS Tulsa, and ZRCV-2, USS Intrepid, were commissioned in 1940. Also in 1940, as part of the overall military buildup authorized by President Roosevelt, construction of all commercial airships was suspended and the ZRCV program was accelerated. ZRCV-3, USS Anchorage, ZRCV-4, USS Sacramento, and ZRCV-5, USS Bon Homme Richard were completed in 1941. All five ships were based at Lakehurst, and beginning in late 1940, they were clandestinely providing ASW air cover for Britain-bound convoys under the guise of “training operations”.
To provide enhanced training for the expanded airship fleet, two ZRN-class training airships were ordered in 1938 to replace the old Los Angeles. ZRN-1 USS San Juan entered service in early 1940, followed by ZRN-2 USS Austin in mid-1941. With a gas capacity of slightly under 4,000,000 cubic feet and a length of 710 feet, the ZRNs had trapezes and launching stations for 3 aircraft. Both ships were based at Sunnyvale, which became the principal training station for the naval airship service. The ships spend the bulk of the war in California.
Following the attack on Pearl Harbor in December 1941, the Navy’s priorities changed. Aircraft carriers and airplanes assumed highest priority, and even those supportive of the airship believed the ZRCV program should be curtailed. Only two ZRCVs already nearing completion were finished: ZRCV-6, USS Honolulu, and ZRCV-7, USS Manila Bay. The remaining ships were cancelled. Half of the airship building sheds were transformed into assembly plants for a variety of naval aircraft. However, design work on the “next generation” ZRCV continued, and three sheds were reserved for the repair, refitting, and modification of the operational airships.
Prior to US entry into the war, the Navy did receive one additional airship from a very unexpected source: Nazi Germany.
When the European War broke out on September 1, 1939, the German airliner LZ-130 Graf Zeppelin had just completed its last crossing to the US of the season and was being serviced at the Lakehurst Air Dock. Because the Graf’s return voyage to Germany would of necessity take it over French and British airspace, and neither Allied nation would guarantee its safety, the ship was interned by the United States. The Graf reigned as a hangar queen until April, 1940, when the United States Navy offered to purchase the ship from the Deutsche Zeppelin-Reederei. After some discussion, the Nazi government approved the sale, believing that this highly visible and successful diplomatic deal with neutral America outweighed any potential risk that the ship might be of military value to the US Navy in the event of a war with Germany.
Following removal of its passenger accommodations, and further weight reduction made necessary by the substitution of less buoyant helium for the ship’s 8,000,000 cubic feet of hydrogen, the ship was reconfigured for naval service. This included the addition of trapezes and launching stations for 5 aircraft along the lower keel. Being significantly larger than the ZRS ships, but smaller and less capable than the ZRCV’s, LZ-130 was neither fish nor fowl, hence her initial addition to the Sunnyvale Naval Airship Training Squadron as ZRN-3, In this guise, she was renamed USS Bismarck. This odd name for a US ship in 1940 was ostensibly in honor of the capital of North Dakota, but there is evidence it was indeed a deliberate double entendre to reflect the ship’s German origins. Following Pearl Harbor she was put into active service and assigned to Rigid Airship Patrol Squadron 3 at Lakehurst. Now designated ZRS-8, she was given yet another name, USS Belleau Wood, which also had German connotations, but of a nature far more suitable to a warship of the US Navy engaged in combat with Germany.
The Second World War
Initially, with the exception of training airships, all rigid airships were operated in the Atlantic, either based at the Lakehurst Naval Air Station, or from several satellite bases. Three separate Patrol Squadrons were established, each with a designated area of operation:
Rigid Airship Patrol Squadron 1 comprised the 4 US-built ZRS-class ships, USS Akron, USS Macon, USS Wichita, and USS Newark. Since its ships were significantly smaller, shorter ranged, and less capable than the ZRCV ships, RAPS-1 only operated on convoy escort, air/sea rescue, and ASW duties in the western half of the Atlantic and Gulf of Mexico. Individual ships were often detailed to secondary bases in Florida and Texas. Unlike RAPS-2 and RAPS-3, the ZRS-ships rarely operated from overseas bases.
Rigid Airship Patrol Squadron 2 included the ZRCVs USS Tulsa, USS Intrepid, USS Anchorage, and USS Sacramento. Initially, RAPS-2 operated either from Lakehurst or satellite bases in Bermuda, Nova Scotia, and occasionally, Iceland, where they provided convoy escort, air/sea rescue, and independent ASW work in the central and eastern Atlantic.
Rigid Airship Patrol Squadron 3 consisted of three ZRCVs (USS Honolulu, USS Bon Homme Richard, and USS Manila Bay) and the former German airliner USS Belleau Wood. RAPS-3 operated primarily from Lakehurst and secondary bases in Puerto Rico, the Canal Zone, and Brazil.
Naval Airship Training Squadron The two US-built ZRNs spend the entire war at Sunnyvale Naval Air Station, California. While training over 1500 and seamen and HTA aircrew for the airship service, they also conducted numerous convoy escort missions between California and Hawaii under virtual wartime conditions. After 1944, both ships were outfitted with advanced air-search radar and were utilized in the secret defense against Japanese balloon bombs, a number of which were destroyed by the airships’ own HTA training units.
The Performance
Prior to late 1943, rigid airships in the Atlantic only operated within their out-and back radius of action (roughly 3000 miles for the ZRS ships and 5000 miles for the ZRCVs). While all the ships were fully capable of one-way transatlantic convoy escort missions with fuel to spare, the only suitable basing and hangar facilities not in German hands were in England, and even here, the Navy did not want to risk its airships in the relatively congested airspace of northwestern Europe where they could be subject to Luftwaffe attack, either on the ground or in transit.
With the successful Anglo-American invasion of North Africa, transatlantic escort missions became possible. Temporary mast facilities were erected at Gibraltar and Casablanca, and by late 1944 the ships could put in at several temporary air stations along the Bay of Biscay in France.
It is probably not an exaggeration to say that US Naval Airships were as instrumental in securing ultimate victory in the Battle of the Atlantic as any other naval aviation assets. They and their hook-on planes provided a degree of 24-hour aerial coverage in the vicinity of convoys which was unmatched by either land-based air or escort carriers. They could launch and retrieve their planes when sea conditions made operation from small escort carriers impossible. From 1943 on, the airships were equipped with the largest and longest ranging air/sea search radars, making them effective ASW units by themselves in event the worst visibility conditions. Although the older ZRS type ships had to rely on other aircraft or surface units to engage and sink German submarines, the ZRCVs could mount their own attacks upon sighting the enemy. Because of their long-endurance, the airships could loiter on ASW searches for up to a week, and although their attack planes had limited range and relatively poor offensive capabilities in comparison with their land-or carrier based counterparts, they could be rearmed and refueled by the airships while on station. For these reasons, being located and engaged by a ZRCV early in its patrol was a u-boat commander’s worst nightmare.
The airships also proved to be far less vulnerable to damage from submarines’ deck guns than had been feared. Unless a lucky hit was made on the control stations, engines, or fuel systems, they were virtually invulnerable to the standard anti-aircraft armament shipped by wartime u-boats. Even when such hits were made, severe damage never led to loss of the ships. In many, instances, airships would return to base with dozens of holes from 20mm, 37mm, and even 88mm shells that had passed harmlessly through the ship, in a few cases without its crew even being aware they had been hit.
Only once was an airship almost downed by a submarine. This involved an engagement between USS Sacramento and U-367 several hundred miles off the Maryland coast in July, 1942. Sacramento encountered the submarine on July 2, shortly after beginning a standard ASW patrol. After being tracked and harassed by the airship’s aircraft for two days, the submarine surfaced, issuing dark black smoke from its conning tower. Believing its foe was seriously damaged and possibly close to surrender, Sacramento closed for a direct engagement. What Sacramento’s captain did not realize is that the smoke was a ruse, serving the double purposes of making the submarine appear damaged and masking the U-boat’s gun crews while they prepared their weapons. As she closed the range, the airship began to receive fire and was quickly struck by several well-aimed 88mm HE rounds which destroyed both portside engine cars and peppered the immediately adjacent gas cells with shrapnel. Shortly thereafter, the control car was struck by a combination of 88mm and 37mm fire, killing 14 crewmen, including the ship’s Captain and Executive Officer. Assuming command in the aft emergency station, the Sacramento’s senior surviving lieutenant immediately broke off the engagement, and the only slightly damaged U-367 sought to escape rather than risk further combat.
Sacramento eventually reached Norfolk Naval air station on the power of only two of her original four engines, and leaking critical amounts of lifting gas. To make land, she had been forced to jettison her entire compliment of aircraft (which, lacking conventional landing gear could not be flown off), all remaining weapons stores, and all standard ballast and unnecessary fuel. In spite of this and emergency repairs to the leaking gas cells, she was still heavy from loss of helium, requiring her to be flown at maximum speed with a 20 degree nose up attitude to maximize dynamic lift. Sacramento landed hard and incurred significant damage to her lower fin and bottom keel, requiring extensive repairs.
Almost certainly, had this action occurred in mid-Atlantic, the ship would have been lost. In a subsequent Board of Inquiry, Sacramento’s captain was faulted for being unnecessarily aggressive in seeking to bring a surfaced enemy into close action without first using his aircraft to determine the extent of damage and ensuring the submarine’s anti-aircraft capabilities were eliminated or significantly degraded. He was also faulted for pressing the engagement and not immediately seeking to disengage when the submarine opened fire. Her commanding lieutenant and 16 crewmen received the Navy Cross in recognition of their skill and courage in saving the damaged airship.
Immediately following the Sacramento inquest, the Navy issued strict orders prohibiting all airships operating alone from attempting to close with surfaced submarines unless they had first used their onboard aircraft to destroy or disable all enemy anti-aircraft batteries.
Not unexpectedly, the U-boat’s crew was celebrated upon returning to Germany. The engagement was also featured in a late 1942 article in the Wehrmacht propaganda magazine Signal, titled “We destroy an enemy zeppelin”. In fairness, the U-boat captain’s belief that the attacking airship was destroyed was logical, given his perspective. However, as was typical for Signal, the propagandist went further and drew a number of strategic conclusions intended to demonstrate the desperate situation the faced by the Allied anti-submarine campaign. Among these were the indirect claim that the “destroyed” airship was in fact the former Graf Zeppelin and the implication that the Americans were driven to use such “flimsy” civil craft in naval patrols due to excessive losses in the Battle of the Atlantic and Pacific theatre. The article also contains the only known photographs of an American airship taken from the enemy perspective. One image of Sacramento drifting bow down barely 600 feet off the surface of the sea, dropping “debris and fuel” (actually ballast), smoking from one engine car, and clearly missing most of its control gondola is particularly striking.
Airships never came in contact with Luftwaffe fighters, but they occasionally encountered long-range Fw-200 Condor reconnaissance-bombers or the odd long-range flying boat. US airships typically carried multiple .50 cal machine guns in the control car and on stations dispersed along the hull or in engine cars to discourage air attack. As the German long range patrol bombers were themselves poorly suited to air-to-air combat, they rarely sought to engage US airships. In the infrequent situations when airships carried Shrike fighters, the German planes could be driven away, but the lightly armed Shrikes rarely pressed home attacks beyond that. In all recorded instances, combat between US airships and German patrol planes was brief and inconclusive. Not a single US rigid airship was lost as a direct result of enemy action, or as far as is known, no German aircraft were downed in such engagements.
One other advantage of the ZRCVs was unexpected. As the war progressed and German submarines began to make greater use of search radars, it became apparent that the giant airships, so visible to the naked eye, were less so to the radars of the day. Their diffuse aluminum structures tended to present a confusing radar signature extremely unlike that of either airplanes or surface ships. Until this was understood, German radar operators frequently misinterpreted radar contacts with airships as flocks of seabirds, chaff, or signal anomalies rather than potentially hostile warcraft.
Nevertheless, the ZRCV’s had inherent flaws which cannot be ignored. Several of these could be predicted by anyone who participated in the peacetime fleet exercises of the late 1930’s.
In general, the reliability of spotting from the airships and their planes did not live up to the optimistic claims made by their supporters in the 1930’s. In good visibility, a giant airship operating at less than 3000 feet is far more visible than a small submarine cruising on the surface. Prior to the widespread use of ASW radar on the airships, German submarine commanders frequently noted with amazement how apparently close a US airship could cruise by without seeing them. Similar problems affected visual scouting from the airships’ planes. Unlike their land- and carrier-based counterparts, which were significantly heavier and more capable, most airship-based scout planes rarely carried a dedicated observer or search radar. To make them even lighter, airship planes usually had less fuel capacity. Since most of them did not have conventional landing gear, they could not land on aircraft carriers or at land bases, meaning they had to remain close to their parent craft. Because of the above factors, HTA unit operating doctrine was very conservative and risk-averse. Only in general scouting, when the planes and airship followed preset courses and speeds, were airplanes operated far beyond the range from which they could see the airship. In most attack situations, when the airship was required to change course and speed, aircraft were usually not launched until the airship itself was in visual range of the target.
The 1930’s impression that airships were vulnerable to weather conditions was also borne out by wartime experience. While the ships could usually survive most strong weather as well or better than any airplane operating at low altitude, they lacked the speed and ceiling to avoid the worst of storm systems. More critically, ground handling remained a major Achilles’ heel of the rigid airship. Even relatively mild winds at airship bases could delay what would otherwise be routine sorties or landings, resulting in many convoys proceeding without effective airship protection. Two airships, USS Newark and USS Tulsa, were lost at sea with all hands as a direct result of violent weather. Just a few weeks after the loss of Tulsa, another ship, USS Honolulu was severely damaged by an unexpectedly strong gust of wind during routine mooring-out operations and was laid up for 3 months.
The Navy initially had no desire to deploy combat airships to the Pacific. Unlike the Atlantic theatre, where the Allies generally enjoyed control of the air, Japan had an extremely effective naval air arm and a history of using it very aggressively. The Navy believed that rigid airships would be extremely vulnerable to Japanese carrier aviation if operated in any active combat zones of the western Pacific. Further, because the Japanese submarine fleet was a relatively insignificant threat to US and other allied merchantmen in the eastern Pacific, little need for the ZRCV or ZRS ships airships as convoy escorts was seen. However, in early 1944, after the Japanese carrier fleet had been largely eliminated and the worst of the German U-boat threat in the Atlantic had apparently passed, the oldest ZRS ship, USS Akron, was detailed to the Pacific Fleet and based at Hilo Naval Air Station in Hawaii. From there, the Akron provided advanced operational training and ASW and air/sea rescue activities between Hawaii, the Marshall Islands - and farther west as the Japanese Empire shrank. Other than accidentally stumbling on the survivors of the torpedoed cruiser USS Indianapolis just days before the end of the war and helping to ensure much of the crew was saved, she did little during her stay in the Pacific.
The ZRS Ships at War In most respects, the early style ZRS-class ships (USS Akron, USS Macon, USS Wichita) were too old to be truly effective in the Battle of the Atlantic. Their hangars could only handle Seafins or Shrikes, giving the ships no offensive capability. Nonetheless, they did provide valuable aerial coverage for convoys crossing the Atlantic. As the war progressed and their military value declined further, they were primarily used in the long-range air/sea rescue role. Being the only craft which could loiter safely for days in U-boar-infested waters to search for and pick up survivors without needing to alight on the water, the ZRS ships literally saved thousands of men who otherwise would have drowned or died from hypothermia.
All three old ZRS ships were immediately retired from service upon the conclusion of the war, and scrapped shortly thereafter. The newer and more modern USS Newark was lost in a violent squall off the coast of Virginia on May 7, 1943 with all hands. USS Belleau Wood, the former Graf Zeppelin, was deflated and kept in mothballs while the Navy attempted to find a civilian buyer willing to refit her as a passenger or cargo ship. But, by this time the capabilities of airplanes had reached the point that there were no takers. She was eventually donated to the Smithsonian Institution in 1951, where she was dismantled for storage.
The ZRCV Ships at War US Navy Records document the destruction of 34 U-boats solely by ZRCV airships or their HTA units. They assisted in the sinking of another 75 submarines by surface units or conventional aircraft. Twice during the war, ZRCV ships operating alone were able to accept the surrender of damaged U-boats. On only three instances did submarines successfully attack convoys escorted by ZRCVs, and in each case, the U-boats were in turn sunk by the airship or other units operating in concert with them.
While the ZRCVs had faults in the primary scouting role, they were at their best when stalking and attacking submerged submarines. Submarines operating at or around periscope/snorkel depth could be relatively easily seen by the low flying airships. Once the target was observed, the airships could drop passive or active sonar into the water while at the same time remaining effectively invisible to the submarine’s hydrophones or sonar. The ships could stay on station for up to a week in some instances and could stalk and harass submerged submarines well beyond the ability of the submarines to stay below the surface. While there are occasions recorded in both US Navy and German records of a particularly skilled U-boat commander evading airships, these situations were few and far between. More typical are these comments by KM Kapitanleutnant Heinrich Zimmer, who surrendered his damaged U-554 to the ZRCV USS Manila Bay on March 12, 1945:
We were returning from patrol off the coast of Brazil when, at 0900, we saw two small planes heading toward us at long range. We initially believed these to be Brazilians based at Belem. I submerged to a depth of 60 meters and our ship survived several poorly aimed depth bombs, presumably dropped by the aircraft. I set a due easterly course at 6 kts and remained submerged for about 20 km. When the attacks were not repeated, I brought the ship to periscope depth and immediately observed an American zeppelin at low altitude to our SSW, approximately sixteen thousand meters distant. It appeared to be heading on a southwesterly course. Believing that the airship probably did not see us, I ordered a dive to 60 m followed by a turn to the NNE to put as much distance between ourselves and the zeppelin. We were not attacked.
We maintained this course for approximately 100 km, at which point I surfaced the ship to replenish the batteries and take bearings. It was now 0300 on the following day and there was a full moon out. We had no trouble spotting the enemy zeppelin loitering stationary about 10 km to north of us. I maintained an easterly course on the surface, hoping that we had not been seen, but we soon came under attack by a single American attack plane we assumed was from the zeppelin. I again dove the ship, this time to 120 m. We detected several distant depth bomb explosions. By now our remaining battery power was becoming critically low. I determined to surface and do my best to engage the zeppelin and its planes, and hopefully drive it off. We surfaced at 1000 and within minutes came under attack from three airplanes who strafed the ship with machine guns and rockets.
We succeeded in destroying one plane and driving off the others, but all topside guns were eventually destroyed and we began taking on water. I then ordered a crash dive and emergency release of oil and decoys, hoping the Americans would believe they had sunk us. We maintained a stationary depth at 45 m until our oxygen virtually ran out, at which time we blew tanks and surfaced. As I feared, the enemy zeppelin was still on station. The huge ship flew right over us and dropped a few small bombs of its own, which damaged the ship’s starboard dive plane and increased our flooding. As neither crew nor ship was in any condition to fight or flee, we signaled our desire to surrender, which the American accepted. Although I intended to scuttle U-554 once everyone was off, several armed American sailors rappelled down from the airship and took command of the bridge while the ship was still being abandoned. One German-speaking sailor let me know in no uncertain terms that his fellows on the zeppelin would murder my crew if the submarine was scuttled – so I didn’t even attempt it. We all knew the war was effectively over and I saw no reason to pretend otherwise. After I and all other officers were taken on board the zeppelin, and all of the crew were set adrift in life rafts, a small American prize crew took command of the ship. After about six hours an American destroyer arrived on the scene, picked up my crew and took U-554 in tow. (US Naval Archives, VIII-78c)
What Kapitanleutnant Zimmer does not report is the fact that, repaired and restored, U-554 is now on display at the US Naval Airship Memorial Museum at Lakehurst Naval Air Station.
Postwar Developments
Although the naval airship program came close to being eliminated in the immediate years following the Second World War, the Cold War with the Soviet Union gave the program temporary new life. Although all the ZRS type ships were removed from service and scrapped shortly following the end of the war, the surviving ZRCVs were refurbished at outfitted for dedicated ASW work. Based on wartime experience, which tended to show that the hook-on scout planes had minimal utility, their compliment of planes was reduced to only four advanced ASW-optimized Harriers. This weight saving allowed for ships to be fitted with a host of sonar and radar systems together with various experimental missile and ASROC systems. The ZRCVs remained in service in this capacity through the mid-1960’s when they were finally supplanted by traditional aircraft carriers, and helicopter-carrying destroyers and frigates. Although both Goodyear-Zeppelin and the Navy’s lighter-than-air bureau proposed several follow-on ZRCV designs, including one for a gigantic 18,000,000 cubic foot nuclear powered ship carrying both fixed- and rotary-winged aircraft, the time for the ASW airship had apparently passed.
However, the large military airship was not quite dead. As a follow-on program, the Department of Defense ordered two large experimental airships which featured radical innovations such as nuclear power, advanced boundary layer control, artificial superheat to improve static lift, increased use of dynamic lift, simplified command and control systems, and other refinements. It was initially hoped these experiments would lead to a fleet of advanced early warning and air control ships, similar in concept to later AWACS aircraft. Two flying prototypes, ZRW-1 and ZMCW-1, were constructed. Rather than being operational units, they were purely flying test beds to evaluate a number of these advanced technologies in various combinations. Although their designations mirrored naval practice and they were operated for the most part by naval personnel, neither airship was a commissioned ship in the US Navy, nor were either of them named. Had they led to a series of operational units, it is believed they would probably have been operated by the US Air Force.
ZRW-1 This was the first and by far the most conservative design of the two. It featured a fairly traditional “zeppelin” design and was completed in 1962. However, with a volume of 12,000,000 cubic feet and a length of 1015 feet ZRW-1 remains the largest airship ever built. It included a large internal bay for the AEW radar systems, communication systems, and required personnel. A second internal structure was provided near the stern for a test nuclear reactor, which was fitted in 1963. The reactor was largely unshielded, protection for the crew being provided by the sheer distance (400 feet) between it and the nearest regular crew stations. The ship was equipped with a system of internal steam heating coils to provide artificial superheat to the gas cells and improve overall lift. The system was also designed so that heating to each cell could be adjusted to experiment with variable heating as a means of changing attitude and trim, rather than the wasteful practice of ballast and gas release. The test reactor was used to heat the steam for the superheating system and provide electricity for the radar and communications suite, but did not power the engines. These were contained in four conventional engine cars the ship was supplied with a single trapeze and landing station for skyhook-equipped aircraft, but did not carry its own planes.
ZMCW-1 This ship was intended to be a much more radical experiment. Her final design was not completed until after ZRW-1 had been flying so some lessons could be derived from experience with the earlier ship. ZMCW-1 was completed in 1964. Its greatest innovation was in its basic structure, which replaced the heavy and redundant zeppelin structure with a stressed aluminum alloy skin over a very light structural framework. This system was actually quite old, having been originally utilized in the small “metal clad” naval airship ZMC-1, which operated successfully throughout the 1930’s. Although sometimes considered a “blimp”, the ZMC-1 was considered a rigid airship because its stressed skin hull could maintain its shape without internal gas pressure up to approximately 20 kts. At higher speeds, positive gas pressure within the hull was created by use of ballonets. Although the BuAer made several proposals for large ships using metal-clad principles in the 1930’s, none were pursued.
As completed, ZMCW-1 was actually somewhat of a hybrid, having significantly more internal structure and compartmentalization than a pure metal-clad would. It contained slightly over 8,000,000 cubic feet of helium in six large cells, each with its own internal pressure ballonet. A separate system was used to regulate air pressure within the overall envelope. The metal hull could maintain its shape at speeds up to 35 kts mph, at which point positive pressure needed to be provided. The AEW radars were mounted within the center of the 2nd gas cell, connecting to the control gondola directly below. An unshielded nuclear reactor was placed within cell No 5, near the stern. The reactor provided power to a steam/electric engine driving a large propeller at the stern, and to four smaller electric drive engines powering variable tilt propellers mounted along the sides of the ship. The reactor also provided gas superheat in the same manner as in ZRW-1. As opposed to all other airships, ZMCW-1 was designed to be operated in a “heavy” state, with positive lift provided by the 4 large steering propellers aligned in a downward direction and/or dynamic flight provided by forward speed. In an emergency, it was calculated that sufficient neutral buoyancy would be provided by the artificial superheat. What this all meant, however, was that ZMCW-1 needed power to remain aloft, and that this power all came from a single source, the central nuclear reactor.
The other radical innovation of the ZMCW-1 involved command and control improvements, together with a concomitant reduction in crew size. The ship could be piloted by a single crewman, who controlled speed, altitude and direction from a single set of controls. Other crew stations monitored and controlled superheat, pressurization, ballast, and the overall operation of the nuclear plant. Thus, whereas the ZRW-1 and all other rigid airships required telegraph communications between the bridge and crew stations throughout the ship, the ZMCW-1 could be effectively flown by fewer than 10 men, all clustered together in the control gondola. ZMCW-1 was provided a single trapeze below the control car for a single plane, but like ZRW-1, it did not carry its own aircraft.
When ZMCW-1 entered flight testing in the summer of 1964, she was almost universally seen as the most sophisticated airship ever to fly. Most of her radical systems worked far better than had been anticipated, and the Department of Defense was prepared to order a series of AEW airships based on the design.
Then disaster struck. On a training flight off Florida on August 12, 1965, pressure controls in ballonet No 1 at the bow of the ship malfunctioned during a routine pressure test, leading to critical positive overpressure. The ship was hovered, and the problem resolved in time to avoid a disastrous explosion of the bow gas cell. However, when standard operating pressure was restored, it became apparent that the localized overpressure had compromised the structural integrity of the stressed-skin hull to the point that it could no longer maintain its shape under neutral pressure. When an attempt was made to resume forward motion, the hull began to crumple inward, placing the internal gas cells in jeopardy. Since the ship could no longer proceed in a forward motion, the rear propeller was reversed. However, the ship was difficult to control in this direction, and it began a series of undulating altitude changes, which further stressed the damaged hull. As a result of damage to the fore gas cell and hull she was also losing helium and altitude. Finally, assisted by favorable winds as much as by her own power, the ship crossed the coast near Daytona. At this point, her crew shut down the nuclear power plant and prepared for a forced landing. Drifting tail-first, ZMCW-1 plowed into the beach, bounced several times, and then came to rest, her hull ripped apart and crumpled into mangled bits of tinfoil. Out of the twelve men on board, all but one survived. Luckily, as designed, the reactor capsule remained intact.
Following the loss of ZMCW-1, the Department of Defense lost all interest in pursing similarly designed airships – and for all intents and purposes – airships in general. The remaining ZRCVs had already been retired and ZRW-1 (with its nuclear power plant and AEW systems removed) was offered for sale to private bidders. But by 1965, there had not been a commercial airship in service in 20 years, and there were no takers. The ship was scrapped in March, 1966.
All of the retired ZRCVs were finally scrapped during in 1969, except for USS Bon Homme Richard, which was transferred to the United States Coast Guard, who operated her intermittently in the air/sea search and rescue role for two years. Her ASW equipment was removed and she carried 5 Super Goose flying boats. She was never formally commissioned as a ship in the Coast Guard, and was only referred to by her Coast Guard designation CGZ-1. In this guise, she was painted in the traditional white Coast Guard livery, with the diagonal red stripe and Coast Guard insignia on her forward hull. She was never particularly popular with “front line” Coast Guard stations, who considered her a “fair weather” craft forced on the service by the Department of Defense and Navy Reserve. She spent most of her time on public relations and recruiting tours on the Atlantic and Gulf Coast. She was finally retired and scrapped in 1972.
Although the last rigid airship flew in 1971, the Graf Zeppelin/Belleau Wood still survived as a dismantled structure occupying space in the old Hangar No. 1 at the Lakehurst Naval Air Station. In 1980, after a survey of the ship’s rings and longitudinal girders showed it retained enough integrity to permit eventual reconstruction, the airship’s framework and Hangar No. 1 were placed on the National Register of Historic Places as unique technological reminders of the rigid airship era. Popular interest in preserving the airship was further stimulated by several Navy proposals in the late 1980’s and early 1990’s to demolish the hangar (and by implication the airship framework within) to make way for training facilities.
As early as 1976, airship enthusiasts on both sides of the Atlantic had already been lobbying for Graf Zeppelin's preservation as a museum ship, and the threats of demolition gave them further ammunition. Several lawsuits and injunctions in the 1990’s prevented demolition of the hangar and the airship’s structure. In 1995, the German government entered the controversy and became an active advocate for the airship’s preservation. Finally, on November 3, 1998, President Clinton and Chancellor Helmut Schroeder signed an agreement in Washington pledging their respective governments to preserve the zeppelin, and share equally in the funding of a project to reconstruct it for static display, should a suitable location be found.
Today, together with the refurbished and relocated Lakehurst Hanger No 1, the 803 foot-long airship is the centerpiece of the huge Lighter than Air Exhibit at the Smithsonian’s National Air and Space Museum (NASM) Annex at Dulles International Airport. As requested by the German government, the ship was reconstructed inside and out as the civil Graf Zeppelin. Also, at Germany’s insistence, she does not sport the huge swastika flags she carried historically. The omission of the swastikas was strongly opposed by the NASM staff and others in the preservation community, who felt this failed to present the ship in a historically accurate context. Others, such as various Jewish-American and human rights groups, agreed with the Germans. For a while, it appeared that this controversy might derail the whole restoration project. Eventually, however, a compromise was reached eliminating the swastika flags from the ship's fins, but allowing accurate Nazi emblems on all photographs, travel posters, brochures, tableware, crew uniforms, and other small items accompanying the airship’s exhibit. Ths compromize als required that all displays with Nazi imagery contained a highly visible notice in several languages reminding the museum visitor that the display of such hate-imagery is illegal in Germany today. Graf Zeppelin’s gas cells are occasionally inflated with an inert mixture of nitrogen and helium to check for rips and tears in the fragile goldbeaters’ skin, but normally the airship is maintained in a non-inflated state. She hangs beside a 1/100 scale model (still 80 feet long) depicting her in her wartime US Navy guise and several restored hook-on aircraft. All internal passenger spaces have been painstakingly replicated. Open for guided public tours, she is the single most popular exhibit in the entire Smithsonian collection.
From time to time, representatives in Congress or the Bundestag put forward resolutions that she be refitted for flight. Following standard NASM practice, the restoration of her engines, control systems, and structure was sufficiently thorough that she probably could be flown. However, this is strongly rejected by historic preservationists on both sides of the Atlantic. In her accurately restored condition, she completely lacks modern avionics and safety systems required for FAA approval, and the installation of such equipment would not be in compliance with historic preservation laws. Even if she could be flown in her historic form, there are not enough people still alive with the training to safely operate her in the air or on the ground, making any attempt to fly her incredibly risky.
Times have changed. Technologies have changed. It is remotely possible that Graf Zeppelin could be inflated with full helium during a routine gas cell check and allowed to “float” at neutral buoyancy in within its display hangar, but she will never ply the open skies again. Nor will any other zeppelin airship.
An alternate history, based on primarily several PoDs in which the airships Akron, Macon, and Hindenburg were not lost in accidents.
A Short History of the United States Naval Airship Service in the Second World War 1941-1945.
Introduction
In view of the tremendous value of the Navy’s rigid airships during the 1941-45 Battle of the Atlantic, it is instructive to realize that, during several periods in the 1920’s and 1930’s, the entire program came very close to being eliminated. For at least the first fifteen years of their service in the US Navy, rigid airships were considered by all but a few advocates as unnecessary and ineffective experiments forced upon the fleet by a few important senior commanders and influential members of Congress representing districts which stood to benefit by the development of an airship industry in the United States.
From the beginning, both traditional “battleship admirals” and the new naval “airpower advocates” had little use for the zeppelin airship. In an environment of limited funding, traditionalists considered airships unproven competitors with light cruisers, submarines, and other surface combatants with clear offensive capabilities. Air power advocates, on the other hand, saw airships as directly competing for scarce aviation funds with flying boats and aircraft carriers. Since only military mission the zeppelin was believed suitable for was unarmed scouting and reconnaissance, and even this had not been proven, most navy officials were unhappy to sacrifice either surface ships or airplanes to build rigid airships.
In fact, early US experience with rigid airships tended to support this pessimism. Both ZR-1, USS Shenandoah, and ZR-2, the unnamed British R-38, were destroyed in crashes before either ship had a chance to demonstrate any military value. Their loss reinforced the impression among the US public and many naval personnel that zeppelin airships were fragile craft, excessively vulnerable to weather conditions and inherently unsound. Lost in these accusations was the fact that neither ZR-1 (a copy of a 1916-vintage German naval zeppelin), and ZR-2 (based on the very lightly-built German “height-climbers, and widely believed to be a particularly faulty design) were not designed for North American weather conditions or rigorous low-altitude fleet scouting operations. Even the highly successful ZR-3, USS Los Angeles, did very little to advance the cause of the rigid airship in the US Navy. Because ZR-3 was a new airship built by the Zeppelin Company as war reparations (to replace German naval zeppelins destroyed by their crews after the armistice), Britain and France insisted that the ship be built as a non-military vessel and not operated as a part of the fleet. Thus, while the ship served well to train crews and “show the flag” across the country for over 10 years, it had little opportunity to demonstrate any value to key decision makers in the Navy Department.
Several factors began to change this situation. Individually, they may not have had much effect, but taken together they ensured the survival and eventual success of the rigid airship in the navy.
The Goodyear-Zeppelin Corporation was founded in 1923, as a joint venture of Goodyear Tire and Rubber Corporation, of Akron, Ohio, and the Zeppelin Company in Germany. This provided US airship designers with full access to all Zeppelin patents and trained design staff. Following in the early 1930’s, Goodyear-Zeppelin as well as the German Zeppelin Company proposed a number of subsidiary commercial airlines to operate trans-Atlantic and trans-Pacific passenger and mail service in Goodyear-Zeppelin built airships.
In 1928, following strong lobbying efforts from the Goodyear-Zeppelin Corporation, and as recommended by the United States Maritime Commission (USMC) and National Advisory Committee on Aeronautics (NACA), the United States Congress passed “An Act for the Establishment of a Commercial Airship Transportation Industry in the United States”, commonly referred to as “the Airship Act”. While this act initially provided no direct funding for the construction of airships or related industries, it set US policy to establish Goodyear-Zeppelin’s airship airlines as the official US passenger and mail carriers in any future trans-Atlantic or trans-Pacific airborne commerce, provided for all commercial airships to be constructed to US Navy specifications and crewed by naval reservists, and require all civil airships and facilities liable for nationalization as naval auxiliaries in the event of war or national emergency.
In 1934, as an important element of the New Deal public works recovery measures implemented by Franklin Roosevelt, the Airship Act was amended to provide funding for several large airship-related construction projects. This included three new airship building sheds at the original Goodyear-Zeppelin Air Dock in Ohio; and four combined building sheds/hangars to be wholly operated by the Navy, two each at existing naval air stations (Sunnyvale, California; and Lakehurst, New Jersey). In subsequent years, the Act was amended further to provide additional Works Progress Association (WPA) funding to build up to eight “civilian” airships similar in basic design to the Navy’s ZRS-4 (USS Akron) type airship, with passenger spaces occupying areas used as airplane hangers in the naval ships. WPA funds were also used to build other infrastructure supporting the commercial airship industry, including helium extraction plants, duralumin fabrication factories, hangers, and passenger/freight handling facilities. Also under the amended Airship Act, NACA established the Merchant Airship Academy near San Diego, California, to provide training to civil (and potential naval) aircrew and air dock workers.
A vision of the future – the ZRS class ships
Despite these positive developments in the civil arena, the role of the rigid airship in the US Navy remained uncertain through the early 1930’s. Goodyear-Zeppelin’s first rigid airship, ZRS-4, USS Akron, entered service in early 1931. A key improvement in this ship and its successors was the provision of an internal hangar capable of handling and servicing five small Curtiss F9C fighter planes. In early training exercises, Akron was operated very conservatively and made little use of little use of its airplanes. Employing tactics more suited to the German Navy in 1916, Akron’s commanders tended to use the airship itself as the scout, only launching planes after contact was made. As they soon discovered, attempting to locate and stealthily track surface ships in a gigantic sliver object flying at only several thousand feet was virtually impossible. In fleet exercises, Akron was often seen and “shot down” by surface ships or ship launched floatplanes before she herself saw the ships. As her crew became more experienced with their ship, Akron began to use her airplanes more as primary scouts, but in two years flying, the ship had not demonstrated any real value to the fleet.
Akron’s sister ship, ZRS-5, USS Macon, entered service in 1933, and at that point things began to improve. Prior to this, all failings of the Akron in fleet exercises were automatically interpreted as a basic failing of the airship as a type, not as a possible product of poor crew performance. With two ships at its disposal, the Navy could now compare the performance of these ships and better understand how and why they performed as they did. Also, as would be expected, there was a natural evolution in the effectiveness of their commanders and crews as they learned from each other and became more experienced with the unique abilities and drawbacks of these giant ships.
By mid-1935, most senior officers accepted Akron and Macon as useful, if not exceptionally valuable, adjuncts of the fleet. The ships’ commanders had developed effective operational doctrine focusing on the use of the ships’ F9C fighters to greatly extend the effectiveness of the airships as strategic scouts, and their crews were both well trained and experienced. In the six “Deep Pacific” fleet problems undertaken in late 1935, the airships proved themselves very effective long range scouts, frequently locating and identifying “enemy” forces well in advance of other scouting vessels or carrier-launched scout planes. Although they often found themselves “shot down” as the problems evolved and the operational areas became more congested, this usually occurred well after they had provided information judged sufficiently important to justify their loss. Nonetheless, there was very little interest in investing additional funds for large and expensive units which lacked any offensive capability of their own. It appeared Akron and Macon would remain the only fleet airships in the US Navy for the foreseeable future.
The Turning Point – Fleet Problem XIII
A key event transforming the Navy’s grudging acceptance of airships to advocacy was Fleet Problem XIII in December, 1935. This featured a simulated “Yellow” attack on a “Blue” base in the Panama Canal Zone. Yellow, based at Pearl Harbor, was tasked with mounting successful airstrikes and shore bombardment of Blue’s base, preparatory to a hypothetical invasion, and was provided a powerful strike force centered on both main fleet carriers (USS Lexington and USS Saratoga) supported by the battleships USS Colorado, USS West Virginia, USS Tennessee, and USS New Mexico, and a mixed screening force of light cruisers, destroyers, and submarines. Blue was deliberately provided a much smaller defensive force comprising only two older battleships (the USS Wyoming and USS Arkansas), the old carrier USS Langley, two heavy cruisers, a few submarines, shore-based flying boats, coastal aviation, and the Akron and Macon. Although the problem was designed primarily to evaluate evolving doctrine regarding the use of aircraft carriers, it was also an ideal situation for the two rigid airships to demonstrate their unique and unmatched capabilities as high speed, high endurance, long range aerial scouts. This, along with a combination of ideal weather conditions for airship scouting and poor decisions by Yellow” fleet commanders, ensured their outstanding and unexpected success.
Operating together under the overall command of Admiral William Moffett, and assisted by an unusual northwesterly tailwind, Akron and Macon moved at extremely high speed toward the Yellow fleet’s project approach route. Very early in the exercise, Macon’s scout planes were able to locate the advance scouting screen for the Yellow force in the open Pacific over 1500 miles from the Canal Zone and report the location and heading to the “Blue” main force. Making excellent use of their scout planes and employing the low cloud cover to maximum effect, the airships were able to swing round the advancing enemy and take up station behind the main Yellow force of battleships and carriers, just outside of visual range. Although Moffett expected his airships would eventually be located and “destroyed” by Yellow’s carrier planes, they remained undetected throughout most of the problem, providing valuable coded information from their F9C scout planes to Blue’s main force.
On the other hand, the Yellow force, under the overall command of Admiral William Halsey, made far less than effective use of its scouting assets. Although radio signals from the airships gave Halsey with a general idea of their relative bearing, he inexplicably made no serious effort to find and “destroy” them, claiming in his debriefing that he was worried his own scout plains might actually collide with them in the low clouds. In other respects, Yellow aerial reconnaissance was unexpectedly poor.
Presuming inaccurately that the weak main Blue force would seek to engage near the Canal Zone under the protection of its land-based aircraft and shore batteries, the Yellow force continued to push ahead toward Panama at high speed. In fact, Blue Force commander Admiral Ernest King adopted the exact opposite strategy. Knowing that Halsey ultimately needed to enter Panamanian waters in range of Blue’s powerful land based air assets, King hoped to attack and eliminate one or both of Yellow’s carriers early in the exercise. This would deprive Halsey of the air support he needed for a successful strike.
Toward the end of the second day of the problem, information provided by the airships allowed the Blue submarine USS Cuttlefish to infiltrate the Yellow screen and “torpedo” USS Lexington, the referee on board the aircraft carrier ruling her “severely damaged” and requiring her to return to Hawaii. Believing that the small Blue fleet would not risk dividing their forces intercept the carrier in its way back to Hawaii, Halsey detailed only two destroyers to escort her.
Guided by information from Akron and Macon King was able to swing out of the way of the Yellow scout screen. Thus, by 0400 on the 3rd day of the exercise, the main Blue force consisting of the carrier USS Langley and the heavy surface units had reached a position less than 150 miles northeast of the Yellow main force. At 0700, the Langley launched its small strike force, which achieved complete surprise. Referees judged the Saratoga’s flight deck irreparably damaged, making her unable to operate aircraft for the remainder of the problem. They also ruled all of Langley’s attacking aircraft lost in the action, but by then the damage was done. In two separate actions made possible by reconnaissance from Akron and Macon, Yellow had lost all of its offensive and defensive air support. Halsey recognized that, in a real combat situation, any attempt to proceed with close-in shore bombardment without air cover could be disastrous. He then sought instead to bring the Blue force containing the Langley into a surface action against his overwhelming force of battleships. Unfortunately, he was unable to locate the Blue ships, and they succeeded in slipping away.
By then, the two Blue airships had divided up, Akron continuing to shadow the main Blue force, with Macon tailing the “crippled” Lexington en route to Hawaii. Since the aircraft carrier had been ruled to be “heavily listing“ after the Cuttlefish’s “torpedo hits” it was not permitted to operate its aircraft, making it essentially a blind sitting duck. Knowing this, Admiral Moffett on the Macon prevailed on the referees to adjust the rules of the problem to presume that, in an actual wartime situation, he would have a small number of 100lb bombs on board which could be changed out for the F9Cs’ external fuel tanks.
As required by the referees, Macon’s HTA unit simulated the “bombing up” of their aircraft by removing and then replacing the fuel tanks on three fighters currently in the hangar being refueled, and less than 2 hours after Moffett received approval from the judges, they were launched. The three planes soon arrived over the “crippled” carrier and made a perfect low angle bombing run across the length of the flight deck. To add insult to injury, the F9C pilots dropped toilet paper rolls as they flew by, all of them hitting the ship’s deck. Faced with such evidence, the referee on Lexington ruled the attack successful. Although the Lexington was not “sunk”, the referee did rule that the attack started fires which resulted in the lost of many aircraft and personnel. In exchange, the three F9Cs were ruled “shot down” by Lexington’s anti-aircraft batteries and escorting destroyers. However, Macon’s attack showed that, in the right situations, aircraft carrying rigid airships could be effective offensive weapons.
As a result of Fleet Problem XIII, the rigid airship went from being considered a tolerated curiosity to a valuable element of the Navy. All of the plans and designs which had been languishing for years at the Navy’s Bureau of Aeronautics (BuAer) Lighter-than-Air section now had a real chance of seeing fruition.
The Prewar Buildup, 1936-1941
The Navy received authorization to procure two more ZRS type ships in the 1936 naval appropriations. The first ship was already well under construction at the Goodyear-Zeppelin Air Dock as the first commercial ship authorized under the amended Airship Act. She was based broadly on the Akron design, but with her hangar bay replaced by internal accommodations for 70 passengers, appropriate commercial staff, freight, and mail. Following a redesign to restore the airplane hangar and bring all other elements of her design to operational naval standards, she entered service as ZRS-6, USS Wichita, in early 1937.
ZRS-7, USS Newark, was designed and built from the keel up as a naval airship and entered service in early 1938. Newark was built to a significantly revised design proposed by the Navy’s Bureau of Aeronautics (BuAer), This replaced the internal airplane hangar and its single trapeze and trolly system for moving planes around with a strengthened keel mounting six individual launching stations and trapezes in tandem along the bottom of the ship for its F9C fighters. Although the planes’ partially exposed condition restricted the ability of the HTA unit to perform extensive maintenance procedures on them, the individual launching stations promised much quicker launching and retrieval operations. This system soon proved itself very efficient and, after USS Newark, no further naval airships were built with internal hangars.
Following completion of the ZRS-7, the ZRCV type ships were introduced. Intended as aerial aircraft carriers with an offensive capability, these became the largest operational airships ever built, being over 900 feet long and containing a volume of over 10,000,000 cubic feet of helium gas. The ships carried trapezes and launching/retrieval stations for up to 10 hook-on aircraft.
In the 1938 naval appropriations bill, funding was authorized for 10 ZRCV ships to be completed over the following four years. The first two, ZRCV-1, USS Tulsa, and ZRCV-2, USS Intrepid, were commissioned in 1940. Also in 1940, as part of the overall military buildup authorized by President Roosevelt, construction of all commercial airships was suspended and the ZRCV program was accelerated. ZRCV-3, USS Anchorage, ZRCV-4, USS Sacramento, and ZRCV-5, USS Bon Homme Richard were completed in 1941. All five ships were based at Lakehurst, and beginning in late 1940, they were clandestinely providing ASW air cover for Britain-bound convoys under the guise of “training operations”.
To provide enhanced training for the expanded airship fleet, two ZRN-class training airships were ordered in 1938 to replace the old Los Angeles. ZRN-1 USS San Juan entered service in early 1940, followed by ZRN-2 USS Austin in mid-1941. With a gas capacity of slightly under 4,000,000 cubic feet and a length of 710 feet, the ZRNs had trapezes and launching stations for 3 aircraft. Both ships were based at Sunnyvale, which became the principal training station for the naval airship service. The ships spend the bulk of the war in California.
Following the attack on Pearl Harbor in December 1941, the Navy’s priorities changed. Aircraft carriers and airplanes assumed highest priority, and even those supportive of the airship believed the ZRCV program should be curtailed. Only two ZRCVs already nearing completion were finished: ZRCV-6, USS Honolulu, and ZRCV-7, USS Manila Bay. The remaining ships were cancelled. Half of the airship building sheds were transformed into assembly plants for a variety of naval aircraft. However, design work on the “next generation” ZRCV continued, and three sheds were reserved for the repair, refitting, and modification of the operational airships.
Prior to US entry into the war, the Navy did receive one additional airship from a very unexpected source: Nazi Germany.
When the European War broke out on September 1, 1939, the German airliner LZ-130 Graf Zeppelin had just completed its last crossing to the US of the season and was being serviced at the Lakehurst Air Dock. Because the Graf’s return voyage to Germany would of necessity take it over French and British airspace, and neither Allied nation would guarantee its safety, the ship was interned by the United States. The Graf reigned as a hangar queen until April, 1940, when the United States Navy offered to purchase the ship from the Deutsche Zeppelin-Reederei. After some discussion, the Nazi government approved the sale, believing that this highly visible and successful diplomatic deal with neutral America outweighed any potential risk that the ship might be of military value to the US Navy in the event of a war with Germany.
Following removal of its passenger accommodations, and further weight reduction made necessary by the substitution of less buoyant helium for the ship’s 8,000,000 cubic feet of hydrogen, the ship was reconfigured for naval service. This included the addition of trapezes and launching stations for 5 aircraft along the lower keel. Being significantly larger than the ZRS ships, but smaller and less capable than the ZRCV’s, LZ-130 was neither fish nor fowl, hence her initial addition to the Sunnyvale Naval Airship Training Squadron as ZRN-3, In this guise, she was renamed USS Bismarck. This odd name for a US ship in 1940 was ostensibly in honor of the capital of North Dakota, but there is evidence it was indeed a deliberate double entendre to reflect the ship’s German origins. Following Pearl Harbor she was put into active service and assigned to Rigid Airship Patrol Squadron 3 at Lakehurst. Now designated ZRS-8, she was given yet another name, USS Belleau Wood, which also had German connotations, but of a nature far more suitable to a warship of the US Navy engaged in combat with Germany.
The Second World War
Initially, with the exception of training airships, all rigid airships were operated in the Atlantic, either based at the Lakehurst Naval Air Station, or from several satellite bases. Three separate Patrol Squadrons were established, each with a designated area of operation:
Rigid Airship Patrol Squadron 1 comprised the 4 US-built ZRS-class ships, USS Akron, USS Macon, USS Wichita, and USS Newark. Since its ships were significantly smaller, shorter ranged, and less capable than the ZRCV ships, RAPS-1 only operated on convoy escort, air/sea rescue, and ASW duties in the western half of the Atlantic and Gulf of Mexico. Individual ships were often detailed to secondary bases in Florida and Texas. Unlike RAPS-2 and RAPS-3, the ZRS-ships rarely operated from overseas bases.
Rigid Airship Patrol Squadron 2 included the ZRCVs USS Tulsa, USS Intrepid, USS Anchorage, and USS Sacramento. Initially, RAPS-2 operated either from Lakehurst or satellite bases in Bermuda, Nova Scotia, and occasionally, Iceland, where they provided convoy escort, air/sea rescue, and independent ASW work in the central and eastern Atlantic.
Rigid Airship Patrol Squadron 3 consisted of three ZRCVs (USS Honolulu, USS Bon Homme Richard, and USS Manila Bay) and the former German airliner USS Belleau Wood. RAPS-3 operated primarily from Lakehurst and secondary bases in Puerto Rico, the Canal Zone, and Brazil.
Naval Airship Training Squadron The two US-built ZRNs spend the entire war at Sunnyvale Naval Air Station, California. While training over 1500 and seamen and HTA aircrew for the airship service, they also conducted numerous convoy escort missions between California and Hawaii under virtual wartime conditions. After 1944, both ships were outfitted with advanced air-search radar and were utilized in the secret defense against Japanese balloon bombs, a number of which were destroyed by the airships’ own HTA training units.
The Performance
Prior to late 1943, rigid airships in the Atlantic only operated within their out-and back radius of action (roughly 3000 miles for the ZRS ships and 5000 miles for the ZRCVs). While all the ships were fully capable of one-way transatlantic convoy escort missions with fuel to spare, the only suitable basing and hangar facilities not in German hands were in England, and even here, the Navy did not want to risk its airships in the relatively congested airspace of northwestern Europe where they could be subject to Luftwaffe attack, either on the ground or in transit.
With the successful Anglo-American invasion of North Africa, transatlantic escort missions became possible. Temporary mast facilities were erected at Gibraltar and Casablanca, and by late 1944 the ships could put in at several temporary air stations along the Bay of Biscay in France.
It is probably not an exaggeration to say that US Naval Airships were as instrumental in securing ultimate victory in the Battle of the Atlantic as any other naval aviation assets. They and their hook-on planes provided a degree of 24-hour aerial coverage in the vicinity of convoys which was unmatched by either land-based air or escort carriers. They could launch and retrieve their planes when sea conditions made operation from small escort carriers impossible. From 1943 on, the airships were equipped with the largest and longest ranging air/sea search radars, making them effective ASW units by themselves in event the worst visibility conditions. Although the older ZRS type ships had to rely on other aircraft or surface units to engage and sink German submarines, the ZRCVs could mount their own attacks upon sighting the enemy. Because of their long-endurance, the airships could loiter on ASW searches for up to a week, and although their attack planes had limited range and relatively poor offensive capabilities in comparison with their land-or carrier based counterparts, they could be rearmed and refueled by the airships while on station. For these reasons, being located and engaged by a ZRCV early in its patrol was a u-boat commander’s worst nightmare.
The airships also proved to be far less vulnerable to damage from submarines’ deck guns than had been feared. Unless a lucky hit was made on the control stations, engines, or fuel systems, they were virtually invulnerable to the standard anti-aircraft armament shipped by wartime u-boats. Even when such hits were made, severe damage never led to loss of the ships. In many, instances, airships would return to base with dozens of holes from 20mm, 37mm, and even 88mm shells that had passed harmlessly through the ship, in a few cases without its crew even being aware they had been hit.
Only once was an airship almost downed by a submarine. This involved an engagement between USS Sacramento and U-367 several hundred miles off the Maryland coast in July, 1942. Sacramento encountered the submarine on July 2, shortly after beginning a standard ASW patrol. After being tracked and harassed by the airship’s aircraft for two days, the submarine surfaced, issuing dark black smoke from its conning tower. Believing its foe was seriously damaged and possibly close to surrender, Sacramento closed for a direct engagement. What Sacramento’s captain did not realize is that the smoke was a ruse, serving the double purposes of making the submarine appear damaged and masking the U-boat’s gun crews while they prepared their weapons. As she closed the range, the airship began to receive fire and was quickly struck by several well-aimed 88mm HE rounds which destroyed both portside engine cars and peppered the immediately adjacent gas cells with shrapnel. Shortly thereafter, the control car was struck by a combination of 88mm and 37mm fire, killing 14 crewmen, including the ship’s Captain and Executive Officer. Assuming command in the aft emergency station, the Sacramento’s senior surviving lieutenant immediately broke off the engagement, and the only slightly damaged U-367 sought to escape rather than risk further combat.
Sacramento eventually reached Norfolk Naval air station on the power of only two of her original four engines, and leaking critical amounts of lifting gas. To make land, she had been forced to jettison her entire compliment of aircraft (which, lacking conventional landing gear could not be flown off), all remaining weapons stores, and all standard ballast and unnecessary fuel. In spite of this and emergency repairs to the leaking gas cells, she was still heavy from loss of helium, requiring her to be flown at maximum speed with a 20 degree nose up attitude to maximize dynamic lift. Sacramento landed hard and incurred significant damage to her lower fin and bottom keel, requiring extensive repairs.
Almost certainly, had this action occurred in mid-Atlantic, the ship would have been lost. In a subsequent Board of Inquiry, Sacramento’s captain was faulted for being unnecessarily aggressive in seeking to bring a surfaced enemy into close action without first using his aircraft to determine the extent of damage and ensuring the submarine’s anti-aircraft capabilities were eliminated or significantly degraded. He was also faulted for pressing the engagement and not immediately seeking to disengage when the submarine opened fire. Her commanding lieutenant and 16 crewmen received the Navy Cross in recognition of their skill and courage in saving the damaged airship.
Immediately following the Sacramento inquest, the Navy issued strict orders prohibiting all airships operating alone from attempting to close with surfaced submarines unless they had first used their onboard aircraft to destroy or disable all enemy anti-aircraft batteries.
Not unexpectedly, the U-boat’s crew was celebrated upon returning to Germany. The engagement was also featured in a late 1942 article in the Wehrmacht propaganda magazine Signal, titled “We destroy an enemy zeppelin”. In fairness, the U-boat captain’s belief that the attacking airship was destroyed was logical, given his perspective. However, as was typical for Signal, the propagandist went further and drew a number of strategic conclusions intended to demonstrate the desperate situation the faced by the Allied anti-submarine campaign. Among these were the indirect claim that the “destroyed” airship was in fact the former Graf Zeppelin and the implication that the Americans were driven to use such “flimsy” civil craft in naval patrols due to excessive losses in the Battle of the Atlantic and Pacific theatre. The article also contains the only known photographs of an American airship taken from the enemy perspective. One image of Sacramento drifting bow down barely 600 feet off the surface of the sea, dropping “debris and fuel” (actually ballast), smoking from one engine car, and clearly missing most of its control gondola is particularly striking.
Airships never came in contact with Luftwaffe fighters, but they occasionally encountered long-range Fw-200 Condor reconnaissance-bombers or the odd long-range flying boat. US airships typically carried multiple .50 cal machine guns in the control car and on stations dispersed along the hull or in engine cars to discourage air attack. As the German long range patrol bombers were themselves poorly suited to air-to-air combat, they rarely sought to engage US airships. In the infrequent situations when airships carried Shrike fighters, the German planes could be driven away, but the lightly armed Shrikes rarely pressed home attacks beyond that. In all recorded instances, combat between US airships and German patrol planes was brief and inconclusive. Not a single US rigid airship was lost as a direct result of enemy action, or as far as is known, no German aircraft were downed in such engagements.
One other advantage of the ZRCVs was unexpected. As the war progressed and German submarines began to make greater use of search radars, it became apparent that the giant airships, so visible to the naked eye, were less so to the radars of the day. Their diffuse aluminum structures tended to present a confusing radar signature extremely unlike that of either airplanes or surface ships. Until this was understood, German radar operators frequently misinterpreted radar contacts with airships as flocks of seabirds, chaff, or signal anomalies rather than potentially hostile warcraft.
Nevertheless, the ZRCV’s had inherent flaws which cannot be ignored. Several of these could be predicted by anyone who participated in the peacetime fleet exercises of the late 1930’s.
In general, the reliability of spotting from the airships and their planes did not live up to the optimistic claims made by their supporters in the 1930’s. In good visibility, a giant airship operating at less than 3000 feet is far more visible than a small submarine cruising on the surface. Prior to the widespread use of ASW radar on the airships, German submarine commanders frequently noted with amazement how apparently close a US airship could cruise by without seeing them. Similar problems affected visual scouting from the airships’ planes. Unlike their land- and carrier-based counterparts, which were significantly heavier and more capable, most airship-based scout planes rarely carried a dedicated observer or search radar. To make them even lighter, airship planes usually had less fuel capacity. Since most of them did not have conventional landing gear, they could not land on aircraft carriers or at land bases, meaning they had to remain close to their parent craft. Because of the above factors, HTA unit operating doctrine was very conservative and risk-averse. Only in general scouting, when the planes and airship followed preset courses and speeds, were airplanes operated far beyond the range from which they could see the airship. In most attack situations, when the airship was required to change course and speed, aircraft were usually not launched until the airship itself was in visual range of the target.
The 1930’s impression that airships were vulnerable to weather conditions was also borne out by wartime experience. While the ships could usually survive most strong weather as well or better than any airplane operating at low altitude, they lacked the speed and ceiling to avoid the worst of storm systems. More critically, ground handling remained a major Achilles’ heel of the rigid airship. Even relatively mild winds at airship bases could delay what would otherwise be routine sorties or landings, resulting in many convoys proceeding without effective airship protection. Two airships, USS Newark and USS Tulsa, were lost at sea with all hands as a direct result of violent weather. Just a few weeks after the loss of Tulsa, another ship, USS Honolulu was severely damaged by an unexpectedly strong gust of wind during routine mooring-out operations and was laid up for 3 months.
The Navy initially had no desire to deploy combat airships to the Pacific. Unlike the Atlantic theatre, where the Allies generally enjoyed control of the air, Japan had an extremely effective naval air arm and a history of using it very aggressively. The Navy believed that rigid airships would be extremely vulnerable to Japanese carrier aviation if operated in any active combat zones of the western Pacific. Further, because the Japanese submarine fleet was a relatively insignificant threat to US and other allied merchantmen in the eastern Pacific, little need for the ZRCV or ZRS ships airships as convoy escorts was seen. However, in early 1944, after the Japanese carrier fleet had been largely eliminated and the worst of the German U-boat threat in the Atlantic had apparently passed, the oldest ZRS ship, USS Akron, was detailed to the Pacific Fleet and based at Hilo Naval Air Station in Hawaii. From there, the Akron provided advanced operational training and ASW and air/sea rescue activities between Hawaii, the Marshall Islands - and farther west as the Japanese Empire shrank. Other than accidentally stumbling on the survivors of the torpedoed cruiser USS Indianapolis just days before the end of the war and helping to ensure much of the crew was saved, she did little during her stay in the Pacific.
The ZRS Ships at War In most respects, the early style ZRS-class ships (USS Akron, USS Macon, USS Wichita) were too old to be truly effective in the Battle of the Atlantic. Their hangars could only handle Seafins or Shrikes, giving the ships no offensive capability. Nonetheless, they did provide valuable aerial coverage for convoys crossing the Atlantic. As the war progressed and their military value declined further, they were primarily used in the long-range air/sea rescue role. Being the only craft which could loiter safely for days in U-boar-infested waters to search for and pick up survivors without needing to alight on the water, the ZRS ships literally saved thousands of men who otherwise would have drowned or died from hypothermia.
All three old ZRS ships were immediately retired from service upon the conclusion of the war, and scrapped shortly thereafter. The newer and more modern USS Newark was lost in a violent squall off the coast of Virginia on May 7, 1943 with all hands. USS Belleau Wood, the former Graf Zeppelin, was deflated and kept in mothballs while the Navy attempted to find a civilian buyer willing to refit her as a passenger or cargo ship. But, by this time the capabilities of airplanes had reached the point that there were no takers. She was eventually donated to the Smithsonian Institution in 1951, where she was dismantled for storage.
The ZRCV Ships at War US Navy Records document the destruction of 34 U-boats solely by ZRCV airships or their HTA units. They assisted in the sinking of another 75 submarines by surface units or conventional aircraft. Twice during the war, ZRCV ships operating alone were able to accept the surrender of damaged U-boats. On only three instances did submarines successfully attack convoys escorted by ZRCVs, and in each case, the U-boats were in turn sunk by the airship or other units operating in concert with them.
While the ZRCVs had faults in the primary scouting role, they were at their best when stalking and attacking submerged submarines. Submarines operating at or around periscope/snorkel depth could be relatively easily seen by the low flying airships. Once the target was observed, the airships could drop passive or active sonar into the water while at the same time remaining effectively invisible to the submarine’s hydrophones or sonar. The ships could stay on station for up to a week in some instances and could stalk and harass submerged submarines well beyond the ability of the submarines to stay below the surface. While there are occasions recorded in both US Navy and German records of a particularly skilled U-boat commander evading airships, these situations were few and far between. More typical are these comments by KM Kapitanleutnant Heinrich Zimmer, who surrendered his damaged U-554 to the ZRCV USS Manila Bay on March 12, 1945:
We were returning from patrol off the coast of Brazil when, at 0900, we saw two small planes heading toward us at long range. We initially believed these to be Brazilians based at Belem. I submerged to a depth of 60 meters and our ship survived several poorly aimed depth bombs, presumably dropped by the aircraft. I set a due easterly course at 6 kts and remained submerged for about 20 km. When the attacks were not repeated, I brought the ship to periscope depth and immediately observed an American zeppelin at low altitude to our SSW, approximately sixteen thousand meters distant. It appeared to be heading on a southwesterly course. Believing that the airship probably did not see us, I ordered a dive to 60 m followed by a turn to the NNE to put as much distance between ourselves and the zeppelin. We were not attacked.
We maintained this course for approximately 100 km, at which point I surfaced the ship to replenish the batteries and take bearings. It was now 0300 on the following day and there was a full moon out. We had no trouble spotting the enemy zeppelin loitering stationary about 10 km to north of us. I maintained an easterly course on the surface, hoping that we had not been seen, but we soon came under attack by a single American attack plane we assumed was from the zeppelin. I again dove the ship, this time to 120 m. We detected several distant depth bomb explosions. By now our remaining battery power was becoming critically low. I determined to surface and do my best to engage the zeppelin and its planes, and hopefully drive it off. We surfaced at 1000 and within minutes came under attack from three airplanes who strafed the ship with machine guns and rockets.
We succeeded in destroying one plane and driving off the others, but all topside guns were eventually destroyed and we began taking on water. I then ordered a crash dive and emergency release of oil and decoys, hoping the Americans would believe they had sunk us. We maintained a stationary depth at 45 m until our oxygen virtually ran out, at which time we blew tanks and surfaced. As I feared, the enemy zeppelin was still on station. The huge ship flew right over us and dropped a few small bombs of its own, which damaged the ship’s starboard dive plane and increased our flooding. As neither crew nor ship was in any condition to fight or flee, we signaled our desire to surrender, which the American accepted. Although I intended to scuttle U-554 once everyone was off, several armed American sailors rappelled down from the airship and took command of the bridge while the ship was still being abandoned. One German-speaking sailor let me know in no uncertain terms that his fellows on the zeppelin would murder my crew if the submarine was scuttled – so I didn’t even attempt it. We all knew the war was effectively over and I saw no reason to pretend otherwise. After I and all other officers were taken on board the zeppelin, and all of the crew were set adrift in life rafts, a small American prize crew took command of the ship. After about six hours an American destroyer arrived on the scene, picked up my crew and took U-554 in tow. (US Naval Archives, VIII-78c)
What Kapitanleutnant Zimmer does not report is the fact that, repaired and restored, U-554 is now on display at the US Naval Airship Memorial Museum at Lakehurst Naval Air Station.
Postwar Developments
Although the naval airship program came close to being eliminated in the immediate years following the Second World War, the Cold War with the Soviet Union gave the program temporary new life. Although all the ZRS type ships were removed from service and scrapped shortly following the end of the war, the surviving ZRCVs were refurbished at outfitted for dedicated ASW work. Based on wartime experience, which tended to show that the hook-on scout planes had minimal utility, their compliment of planes was reduced to only four advanced ASW-optimized Harriers. This weight saving allowed for ships to be fitted with a host of sonar and radar systems together with various experimental missile and ASROC systems. The ZRCVs remained in service in this capacity through the mid-1960’s when they were finally supplanted by traditional aircraft carriers, and helicopter-carrying destroyers and frigates. Although both Goodyear-Zeppelin and the Navy’s lighter-than-air bureau proposed several follow-on ZRCV designs, including one for a gigantic 18,000,000 cubic foot nuclear powered ship carrying both fixed- and rotary-winged aircraft, the time for the ASW airship had apparently passed.
However, the large military airship was not quite dead. As a follow-on program, the Department of Defense ordered two large experimental airships which featured radical innovations such as nuclear power, advanced boundary layer control, artificial superheat to improve static lift, increased use of dynamic lift, simplified command and control systems, and other refinements. It was initially hoped these experiments would lead to a fleet of advanced early warning and air control ships, similar in concept to later AWACS aircraft. Two flying prototypes, ZRW-1 and ZMCW-1, were constructed. Rather than being operational units, they were purely flying test beds to evaluate a number of these advanced technologies in various combinations. Although their designations mirrored naval practice and they were operated for the most part by naval personnel, neither airship was a commissioned ship in the US Navy, nor were either of them named. Had they led to a series of operational units, it is believed they would probably have been operated by the US Air Force.
ZRW-1 This was the first and by far the most conservative design of the two. It featured a fairly traditional “zeppelin” design and was completed in 1962. However, with a volume of 12,000,000 cubic feet and a length of 1015 feet ZRW-1 remains the largest airship ever built. It included a large internal bay for the AEW radar systems, communication systems, and required personnel. A second internal structure was provided near the stern for a test nuclear reactor, which was fitted in 1963. The reactor was largely unshielded, protection for the crew being provided by the sheer distance (400 feet) between it and the nearest regular crew stations. The ship was equipped with a system of internal steam heating coils to provide artificial superheat to the gas cells and improve overall lift. The system was also designed so that heating to each cell could be adjusted to experiment with variable heating as a means of changing attitude and trim, rather than the wasteful practice of ballast and gas release. The test reactor was used to heat the steam for the superheating system and provide electricity for the radar and communications suite, but did not power the engines. These were contained in four conventional engine cars the ship was supplied with a single trapeze and landing station for skyhook-equipped aircraft, but did not carry its own planes.
ZMCW-1 This ship was intended to be a much more radical experiment. Her final design was not completed until after ZRW-1 had been flying so some lessons could be derived from experience with the earlier ship. ZMCW-1 was completed in 1964. Its greatest innovation was in its basic structure, which replaced the heavy and redundant zeppelin structure with a stressed aluminum alloy skin over a very light structural framework. This system was actually quite old, having been originally utilized in the small “metal clad” naval airship ZMC-1, which operated successfully throughout the 1930’s. Although sometimes considered a “blimp”, the ZMC-1 was considered a rigid airship because its stressed skin hull could maintain its shape without internal gas pressure up to approximately 20 kts. At higher speeds, positive gas pressure within the hull was created by use of ballonets. Although the BuAer made several proposals for large ships using metal-clad principles in the 1930’s, none were pursued.
As completed, ZMCW-1 was actually somewhat of a hybrid, having significantly more internal structure and compartmentalization than a pure metal-clad would. It contained slightly over 8,000,000 cubic feet of helium in six large cells, each with its own internal pressure ballonet. A separate system was used to regulate air pressure within the overall envelope. The metal hull could maintain its shape at speeds up to 35 kts mph, at which point positive pressure needed to be provided. The AEW radars were mounted within the center of the 2nd gas cell, connecting to the control gondola directly below. An unshielded nuclear reactor was placed within cell No 5, near the stern. The reactor provided power to a steam/electric engine driving a large propeller at the stern, and to four smaller electric drive engines powering variable tilt propellers mounted along the sides of the ship. The reactor also provided gas superheat in the same manner as in ZRW-1. As opposed to all other airships, ZMCW-1 was designed to be operated in a “heavy” state, with positive lift provided by the 4 large steering propellers aligned in a downward direction and/or dynamic flight provided by forward speed. In an emergency, it was calculated that sufficient neutral buoyancy would be provided by the artificial superheat. What this all meant, however, was that ZMCW-1 needed power to remain aloft, and that this power all came from a single source, the central nuclear reactor.
The other radical innovation of the ZMCW-1 involved command and control improvements, together with a concomitant reduction in crew size. The ship could be piloted by a single crewman, who controlled speed, altitude and direction from a single set of controls. Other crew stations monitored and controlled superheat, pressurization, ballast, and the overall operation of the nuclear plant. Thus, whereas the ZRW-1 and all other rigid airships required telegraph communications between the bridge and crew stations throughout the ship, the ZMCW-1 could be effectively flown by fewer than 10 men, all clustered together in the control gondola. ZMCW-1 was provided a single trapeze below the control car for a single plane, but like ZRW-1, it did not carry its own aircraft.
When ZMCW-1 entered flight testing in the summer of 1964, she was almost universally seen as the most sophisticated airship ever to fly. Most of her radical systems worked far better than had been anticipated, and the Department of Defense was prepared to order a series of AEW airships based on the design.
Then disaster struck. On a training flight off Florida on August 12, 1965, pressure controls in ballonet No 1 at the bow of the ship malfunctioned during a routine pressure test, leading to critical positive overpressure. The ship was hovered, and the problem resolved in time to avoid a disastrous explosion of the bow gas cell. However, when standard operating pressure was restored, it became apparent that the localized overpressure had compromised the structural integrity of the stressed-skin hull to the point that it could no longer maintain its shape under neutral pressure. When an attempt was made to resume forward motion, the hull began to crumple inward, placing the internal gas cells in jeopardy. Since the ship could no longer proceed in a forward motion, the rear propeller was reversed. However, the ship was difficult to control in this direction, and it began a series of undulating altitude changes, which further stressed the damaged hull. As a result of damage to the fore gas cell and hull she was also losing helium and altitude. Finally, assisted by favorable winds as much as by her own power, the ship crossed the coast near Daytona. At this point, her crew shut down the nuclear power plant and prepared for a forced landing. Drifting tail-first, ZMCW-1 plowed into the beach, bounced several times, and then came to rest, her hull ripped apart and crumpled into mangled bits of tinfoil. Out of the twelve men on board, all but one survived. Luckily, as designed, the reactor capsule remained intact.
Following the loss of ZMCW-1, the Department of Defense lost all interest in pursing similarly designed airships – and for all intents and purposes – airships in general. The remaining ZRCVs had already been retired and ZRW-1 (with its nuclear power plant and AEW systems removed) was offered for sale to private bidders. But by 1965, there had not been a commercial airship in service in 20 years, and there were no takers. The ship was scrapped in March, 1966.
All of the retired ZRCVs were finally scrapped during in 1969, except for USS Bon Homme Richard, which was transferred to the United States Coast Guard, who operated her intermittently in the air/sea search and rescue role for two years. Her ASW equipment was removed and she carried 5 Super Goose flying boats. She was never formally commissioned as a ship in the Coast Guard, and was only referred to by her Coast Guard designation CGZ-1. In this guise, she was painted in the traditional white Coast Guard livery, with the diagonal red stripe and Coast Guard insignia on her forward hull. She was never particularly popular with “front line” Coast Guard stations, who considered her a “fair weather” craft forced on the service by the Department of Defense and Navy Reserve. She spent most of her time on public relations and recruiting tours on the Atlantic and Gulf Coast. She was finally retired and scrapped in 1972.
Although the last rigid airship flew in 1971, the Graf Zeppelin/Belleau Wood still survived as a dismantled structure occupying space in the old Hangar No. 1 at the Lakehurst Naval Air Station. In 1980, after a survey of the ship’s rings and longitudinal girders showed it retained enough integrity to permit eventual reconstruction, the airship’s framework and Hangar No. 1 were placed on the National Register of Historic Places as unique technological reminders of the rigid airship era. Popular interest in preserving the airship was further stimulated by several Navy proposals in the late 1980’s and early 1990’s to demolish the hangar (and by implication the airship framework within) to make way for training facilities.
As early as 1976, airship enthusiasts on both sides of the Atlantic had already been lobbying for Graf Zeppelin's preservation as a museum ship, and the threats of demolition gave them further ammunition. Several lawsuits and injunctions in the 1990’s prevented demolition of the hangar and the airship’s structure. In 1995, the German government entered the controversy and became an active advocate for the airship’s preservation. Finally, on November 3, 1998, President Clinton and Chancellor Helmut Schroeder signed an agreement in Washington pledging their respective governments to preserve the zeppelin, and share equally in the funding of a project to reconstruct it for static display, should a suitable location be found.
Today, together with the refurbished and relocated Lakehurst Hanger No 1, the 803 foot-long airship is the centerpiece of the huge Lighter than Air Exhibit at the Smithsonian’s National Air and Space Museum (NASM) Annex at Dulles International Airport. As requested by the German government, the ship was reconstructed inside and out as the civil Graf Zeppelin. Also, at Germany’s insistence, she does not sport the huge swastika flags she carried historically. The omission of the swastikas was strongly opposed by the NASM staff and others in the preservation community, who felt this failed to present the ship in a historically accurate context. Others, such as various Jewish-American and human rights groups, agreed with the Germans. For a while, it appeared that this controversy might derail the whole restoration project. Eventually, however, a compromise was reached eliminating the swastika flags from the ship's fins, but allowing accurate Nazi emblems on all photographs, travel posters, brochures, tableware, crew uniforms, and other small items accompanying the airship’s exhibit. Ths compromize als required that all displays with Nazi imagery contained a highly visible notice in several languages reminding the museum visitor that the display of such hate-imagery is illegal in Germany today. Graf Zeppelin’s gas cells are occasionally inflated with an inert mixture of nitrogen and helium to check for rips and tears in the fragile goldbeaters’ skin, but normally the airship is maintained in a non-inflated state. She hangs beside a 1/100 scale model (still 80 feet long) depicting her in her wartime US Navy guise and several restored hook-on aircraft. All internal passenger spaces have been painstakingly replicated. Open for guided public tours, she is the single most popular exhibit in the entire Smithsonian collection.
From time to time, representatives in Congress or the Bundestag put forward resolutions that she be refitted for flight. Following standard NASM practice, the restoration of her engines, control systems, and structure was sufficiently thorough that she probably could be flown. However, this is strongly rejected by historic preservationists on both sides of the Atlantic. In her accurately restored condition, she completely lacks modern avionics and safety systems required for FAA approval, and the installation of such equipment would not be in compliance with historic preservation laws. Even if she could be flown in her historic form, there are not enough people still alive with the training to safely operate her in the air or on the ground, making any attempt to fly her incredibly risky.
Times have changed. Technologies have changed. It is remotely possible that Graf Zeppelin could be inflated with full helium during a routine gas cell check and allowed to “float” at neutral buoyancy in within its display hangar, but she will never ply the open skies again. Nor will any other zeppelin airship.
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