My Sony Quantum Multiversal Transmogrifier is finally up and running. Below is the text of a 2010 American Heritage article from a universe in which the Hindenburg did not explode at Lakehurst in 1937:
A Surprising Gift
When the European War broke out on September 1, 1939, the German Zeppelin airliner LZ-129 Hindenburg had just completed its final westbound crossing of the North Atlantic season and was being serviced at the Lakehurst Air Dock. The outbreak of war complicated matters for the Deutsche Zeppelin-Reederei, her German operators. The majority of the ship’s east-bound passengers (33) were Americans, most of whom had cancelled their reservations due to the war. Of necessity, the Hindenburg’s return voyage to Germany would take it over French or British airspace, or areas the two Allied powers dominated. Because of a belief (later borne out in captured Luftwaffe documents) that the Hindenburg and its sister Graf Zeppelin II had been used earlier in 1939 to probe British air defenses under the guise of civilian training flights, neither Allied nation would guarantee the airship’s safety.
As with German steamships trapped in US ports and unable or unwilling to attempt a return to Germany, the Hindenburg was interned by the United States. The airship reigned at Lakehurst as a hangar queen until February, 1940, when the United States Navy offered to purchase the ship from the Deutsche Zeppelin-Reederei for a nominal sum of $50,000, which was a tiny fraction of the ship’s original cost. This offer was made, not so much to procure another operational rigid airship for the Navy, but to remove the zeppelin from Hangar 1 at Lakehurst and make room for the Navy’s small fleet of non-rigid airships. Somewhat surprisingly, the Nazi government accepted the offer, requesting only that the ship would not be based in the Atlantic or transferred to any Allied nation. The Germans apparently believed 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.
Preparing for Navy Service
Initially the Navy intended simply to scrap the ex-German ship. Ever since the loss of the USS Macon in 1935, the Navy had no rigid airships, and had no serious plans to purchase any more. However, the Navy’s Bureau of Aeronautics (BuAer) had continued to scheme possible new airships, ending in the “ZRN” proposals of 1939 for a modest 3,000,000 cubic foot training airship to further explore the operation of aircraft from rigid airships. Given that the Hindenburg had essentially been dropped into the Navy’s lap free of charge, BuAer successfully argued that it would be foolish to look such a gift in the mouth. The infrastructure and trained personnel still existed to maintain and operate rigid airships, and the cost of refitting Hindenburg as a naval airship would be miniscule compared to the cost to design and build an entirely new ship. The flying aircraft carrier concept embodied in the USS Akron and Macon was resurrected and the large Hindenburg would be a much larger laboratory to put it in operation, than the proposed ZRN. In June the now-unnamed airship was flown to Goodyear-Zeppelin’s Airdock at Akron for conversion.
The first task involved converting the ship for helium use. This was not as easy as it might seem, because helium has significantly less lifting power than hydrogen. Not only must the structure of the ship be lightened, heavy water-recovery apparatus needed to be installed near the engine cars to replenish water ballast, since the expensive helium could not simply be valved off to compensate for fuel use. Without conversion, the Hindenburg would be militarily useless, even as a training airship.
The main area where the structure of the ship could be significantly lightened without affecting its structural strength was by reducing or eliminating altogether the spacious and relatively luxurious internal passenger bay. Not only would this lighten the structure, it would allow for an increase in the hull volume devoted to lifting gas. BuAer and the Goodyear engineers also saw this as an opportunity to explore various options for stowing and launching airplanes. Initially, two schemes were considered.
Option 1 involved a conversion of the airship’s passenger accommodation bay to house an airplane hangar. This was essentially a duplication of the scheme used on the ill-fated USS Akron and USS Macon and was seen as the quickest conversion. Weight would be reduced by reduction in size of the former passenger bay and the elimination of the internal partitions and facilities associated with the passenger amenities, but the space devoted to lifting gas would not be substantially enlarged. It was calculated that two aircraft equivalent in size and weight to an SBD Dauntless could be maintained in the hangar, with an additional one perched as necessary on a supplemental exterior trapeze attached to the lower keel aft of the hangar. This would, however, require cutting a hangar opening on the ship’s lower keel between two mainframes – introducing possible structural weakness.
Option 2 would exhibit the same aircraft handling accommodations as the first option, but to improve the airship’s useful lift, a new bay and gas cell would be added behind the hangar. Although this option would allow at least two additional airplanes to be routinely carried by the ship, it was by far the most costly and time-consuming, requiring as it would extensive surgery on the ship’s hull. This option also retained the problematic hangar opening through the main keel.
The approach finally implemented was based on an unsolicited proposal prepared by Consolidated Aviation, a firm that had previously focused on providing the Navy with flying boats and floatplanes. Seeking to expand its market, Consolidated had previously prepared a series of patents for aircraft handling and stowage on large rigid airships similar in basic design to the Hindenburg. Although BuAer had not requested outside proposals, Consolidated’s proposal was developed into a series of design sketches by BuAer’s C.P. Burgess. This design eliminated the airship’s interior hangar space altogether to increase useful lift and added a lightly framed exterior “maintenance deck” below the main hull just aft of the control car. This scheme retained the integrity of the lower main keel. The “maintenance deck” would not house any aircraft on a regular basis. Four planes would be stowed semi-externally on individual trapeze stations along the main keel, but for servicing and bombing up they could be temporarily landed in the small maintenance deck one at a time. Planes could also be launched from the deck, meaning that, in an emergency, the reconstructed airship could carry up to five aircraft.
Elimination of an internal airplane hangar and its replacement by a series of semi-external trapeze stations along the lower keel was a key feature of the stillborn ZRCV-class considered by BuAer in 1938, further making this design attractive to US Navy airshipmen.
Another problem resulting from Hindenburg’s conversion to helium was never fully resolved. This was the difficulty in maintaining equilibrium during the operation of the hook-on aircraft.
“Flying” an airship of any kind effectively requires managing a careful balance between the lift provided by the hydrogen or helium lifting gas and the weight of consumable stores, such as fuel, ballast, and so forth. As ballast is dropped or fuel is expended, an airship will rise unless lifting gas is valved off or other mechanical or aerodynamic forces can be applied to push the ship downward.
In an airship using hydrogen, valving gas is an efficient measure to maintain equilibrium, because the gas is relatively inexpensive and easily produced. Helium, in the 1940’s, was still a very rare and very expensive commodity, and the valving of helium from Naval airships was strongly discouraged, except in an emergency.
In the 1930’s, Naval airships were fitted with expensive water recovery apparatus to collect water ballast from engine exhausts. The Akron and Macon were also provided with swiveling propellers that could be directed in a manner to help counteract an airships static lift. On the modified Hindenburg, water recovery apparatus would work reasonably well for routine flight, but the release of hook-on aircraft, each weighing a ton or more, was a significant and virtually instantaneous weight change. The aircraft-carrying Akron and Macon managed this fairly well because of their outriggers with swiveling propellers and the very slow rate with which the extremely small and light F9C fighters were be deployed from their internal hangars.
The Hindenburg, however would be able to release its five hook-on planes virtually instantaneously, and these more modern airplanes would be significantly heavier. Even when flying nose-down at a high speed to provide negative aerodynamic lift during aircraft launching operations, the only way Hindenburg could manage this problem during a sortie of up to a week’s duration without valving off an excessive amount of Helium, was by limiting flight operations to a relatively few aircraft at a time, with long intervals between air operations in which ballast was recovered by the recovery equipment or by low level siphoning of seawater aboard.
Conversion of the former Hindenburg was completed in September 1940, and upon her return flight to Lakehurst she was christened USS Bismarck. As requested by Germany, the airship was not assigned to a fleet unit. She was designated ZRN-1 and initially deployed at Sunnyvale NAS in California as a training airship. This name Bismarck, somewhat odd for a US ship in 1940, was ostensibly in honor of the capital of North Dakota, but there is anecdotal evidence it was indeed a deliberate double entendre to reflect the ship’s German origins. Probably because of the increasing unpopularity of Germany in the 1940-41 period, the name “Bismarck” was rarely used in official correspondence, communiques, or public press releases.
Over the next year, under the command of Lt. Commander Herbert Wiley, who had commanded USS Macon previously, ZRN-1 operated out of Sunnyvale, conducting several long-distance flights to Hawaii, Dutch Harbor, Guam, Midway, and the Philippines to assess the ship’s suitability as a long-range strategic scout and transport as well as her ability to operate from remote and relatively limited ground facilities. The ship was also employed in several fleet problems as well as anti-submarine and air-sea rescue exercises. These tended to show that the zeppelin was much more effective operating on solitary ASW patrols or in strategic reconnaissance than close operations with the fleet – something that veterans of the fleet problems of 1931-1935 would have known. Building on Wiley’s experience with USS Macon, ZRN-1 and her crew became adept at using the ship’s hook-on aircraft and RDF equipment to scout vast expanses of sea and, on one occasion, discover and render assistance to a foundering fishing vessel west of Hawaii. By November 1941, even previous opponents of the rigid airship in Navy service acknowledged the utility of ZRN-1, especially in anti-submarine work and for long range maritime reconnaissance.
During the training exercises ZRN-1 experimented with a variety of aircraft, suitably modified for operations from the ship’s trapezes. This included O2SU Kingfishers (both with and without floats), F3A and F4F fighters, SBD attack planes, and – most interestingly – twin engined Grumman Goose floatplanes, and the experimental Grumman XF5F twin engined fighter to determine the size and weight of airplanes that could reliably be landed and launched from the trapeze stations along the lower keel. Eventually, 15 specially lightened F4F Wildcat fighters and SBD Dauntless bombers were ordered by the Navy for service operation from the airship. The airship also trained a cadre of 15 pilots experienced in the operation of hook-on aircraft as its HTA (Heavier than Air) unit, including several who had earlier flown F9C Sparrowhawks from USS Macon. The airship eventually trained two separate crews, allowing men to be rotated between shore and air duty without fatigue.
Wartime Operations
Following the German declaration of War in December 1941, the airship was put into active service and deployed to Lakehurst to assist in convoy escort and anti-submarine work in the North Atlantic. With this change in function, she was also redesignated an “airship aircraft carrier” (ZRCV)and given the new designator “ZRCV-1.” Thanks to her semi-exterior “maintenance deck” and trapeze stations along her keel she could operate a much wider variety of aircraft than the earlier Akron and Macon type, including attack aircraft. She was also renamed USS Belleau Wood, a name that also had German connotations, but of a nature far more suitable to a warship of the US Navy engaged in combat with Germany. Her usual flight complement consisted of five lightened Douglass SBD Dauntless scout/attack planes. As with the earlier F9Cs operated from USS Macon, the landing gear and their retraction mechanisms were removed, they were unarmored, lacked self-sealing fuel tanks, and were not equipped with defensive machine guns. From 1941 through 1943 she was based at Lakehurst, although on occasion she deployed to temporary facilities in Iceland or Puerto Rico. Because of Japan’s effective and aggressive naval air arm, no consideration was ever given to her deployment in the Pacific. Later, in 1944-45, she was often based out of Bartolomeu de Gusmão, Brazil, which had a large airship hanger originally built to house and service the Hindenburg on its South American service, and so was ideally suited to the American airship.
It is probably not an exaggeration to say that USS Belleau Wood proved that rigid airships could have been an important weapon in the Battle of the Atlantic had more than one of them been available. She and her 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.
However, it was also discovered that the airship (both rigid and non-rigid) was really not ideally suited to close convoy escort. Airships were highly visible from a surfaced submarine at long distances. This frequently allowed submarines to locate and converge on convoys under close airship escort in situations where the merchants might otherwise have gone unnoticed. Also, the close proximity of a visible airship to convoys at times had the opposite, equally unhelpful effect, of making a submarine abort a possible attack when effective escorts were present that could destroy the U-boat.
As a result, the operating doctrine for Belleau Wood shifted away from close escort to independent patrol focused on the discovery and destruction of U-boats. This was particularly her role in the mid-Atlantic “gap” outside the range and endurance of most shore-based ASW aircraft. Also, she could conduct sweeps and patrols at night and in poor visibility conditions that grounded many carrier aircraft. The airship could also operate her aircraft when rough sea conditions made operations from small escort carriers problematic. As patrol vessels, the zeppelin’s relatively high speed in comparison to surface ships and extremely high endurance in comparison with fixed-wing aircraft played real dividends.
From 1943 Belleau Wood was equipped with the air/sea search radars, towed and buoy sonar and hydrophones, and magnetic anomaly detection (MAD) equipment. Although her weapon payload was limited, she or her aircraft could deploy a small number of depth bombs, standard bombs, and other anti-ship weapons. Toward the end of the war, acoustic homing torpedoes were added to this arsenal. Because of the additional weight, her compliment of aircraft was reduced to two hook-on aircraft in 1944-45. Nonethless, the airship was more than capable of both finding submarines and pressing home attacks.
Because of her long flight endurance, Belleau Wood could loiter on ASW searches in the “gap” for up to a week, and although her specially modified and lightened 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 to some extent by the airship while on station. For these reasons, being located, tracked, and engaged by a rigid airship was one of a U-boat commander’s worst nightmares. Belleau Wood’s log records one confirmed and three probable U-boat sinkings.
In addition, on one occasion, Belleau Wood was even successful in capturing a German submarine. A detailed description of this action was recorded by KM Kapitanleutnant Heinrich Zahler, who surrendered his damaged U-554 to the airship on March 12, 1945:
We were returning from patrol off the coast of Brazil when, at 0900, we saw two small planes of the Douglas type 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 two 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 two distant depth bomb explosions. By now our remaining battery power was becoming critically low. It was obvious we would not shake our pursuer, so 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 two airplanes who strafed the ship with machine guns and rockets.
We succeeded in destroying one plane and driving off the other, but all topside guns were 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 could not bottom but disengaged the screws and 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 further 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. The airship took station approximately 150 meters over us. Although I intended to scuttle U-554 once everyone was off, several armed American sailors rappelled down from the zeppelin 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 me and 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 our submarine. 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)
This action resulted in the Bellau Wood’s company being awarded a Battle Star. Her Captain, Lt. Commander John Mansfield and Executive Officer, William T. Jane, Jr., were awarded the Silver Star. Several other crewmembers received Bronze Stars.
Prior to mid-1944, Belleau Wood only operated within its out-and back radius of action (roughly 3500 miles) of Lakehurst or Brazil. As a former transatlantic airliner fully capable of transatlantic convoy escort or patrol 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. On only one occasion was the airship engaged by a German aircraft – a long range Ju 290 maritime reconnaissance plane she happened to encounter in the Bay of Biscay. Visibility conditions were relatively poor and the action was inconclusive. The Junkers made one pass at the airship spraying her randomly with machine gun fire to no effect, while the airship’s own .50 cal. machine guns mounted in her control and engine cars were equally ineffective. Lacking any fighters on board, Belleau Wood launched two unarmed SBDs, hoping this would scare off the German aircraft. Although the airship’s log credits the SBDs with driving off the German, it is much more likely the Ju 290 merely broke off the chance engagement because of the poor visibility.
Somewhat unexpectedly, the rigid airship proved to be less vulnerable to damage from submarines’ deck guns than had been feared. USS Belleau Wood was fired upon by surfaced submarines on a number of occasions. Standard HE and AP rounds would often pass through the airship’s envelope with negligible damage or gas loss. Unless a lucky hit was made on the control stations, engines, critical structural members, or fuel systems, a large rigid airship was virtually invulnerable to the standard anti-aircraft armament shipped by wartime U-boats. Even when such hits were made on Belleau Wood, the ship never came close to destruction. At one time or another the airship returned to base with 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.
Belleau Wood’s successes in the anti-submarine role were not lost on the Navy, and in 1943, BuAer initiated design studies for a specialized ASW airship considerably larger and more capable than the modified Hindenburg. Designated the ZRCV-ASW, these plans called for a 10,000,000 cubic foot airship fitted with a complete array of ASW sensors and weapons, together with a squadron of as many as eight dedicated ASW aircraft. However, time had passed the rigid airship by.
The following 1943 congressional testimony from Admiral Ernest J. King regarding the new airships sums up the situation well:
The Belleau Wood has proved to be extremely useful against the German u-boats. I was a proponent of rigid airships during the 1930’s and am glad we have one working with the Atlantic Fleet now. However, I do not see us building any more of them. Such vessels would represent a dangerous diversion of resources from what the Navy really needs: more effective combat ships, fleet oilers, and airplanes. For the cost of one new airship, we could build several destroyer escorts and as many as 15 anti-submarine long range patrol planes. We need those ships and planes far more than we need several more large airships, despite their unique abilities.”
Death and Resurrection
USS Belleau Wood served until the end of the War and was retained in flight status as a US Navy recruitment tool until 1947. She was decommissioned in 1948 and after desultory attempts by the Navy to interest various US and foreign commercial operators in the ship, the Navy transferred her to the Goodyear Corporation, whose chairman, Paul Lichtfield, remained an advocate for rigid airships in commerce and even military applications. Now unnamed, the ship was flown to Akron, Ohio, and laid up in the old Goodyear-Zeppelin Airdock while Goodyear developed plans for her operation, both in public relations and research. She occasionally flew to evaluate various schemes for “future airships”, including even the installation of a dummy “atomic power plant” within her hull to evaluate the feasibility of mounting such a power plant in rigid airships.
Nothing came of these plans, however, and by 1955, the airship served only as a non-flying “flagship” of Goodyear’s fleet of blimps and as a local tourist attraction. In this role, the airship survived as a poorly maintained relic occupying space the hangar until the late 1970’s. In 1979, Goodyear sought to use its giant hangar for other purposes, and offered the ship for donation to the Smithsonian Institution or other flight museums around the nation. In 1980, after a survey of the ship’s rings and longitudinal girders showed the hull retained enough integrity to permit full reconstruction, the airship was placed on the National Register of Historic Places as a unique technological reminder of the rigid airship era.
Also, as early as 1976, airship enthusiasts on both sides of the Atlantic had been lobbying Goodyear and the US Government for her reconstruction and preservation as a museum ship, and continuing threats of possible demolition gave them further ammunition.
The ship and its final status remained in limbo for almost twenty years until, 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 provide funding 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. A space was found at the Smithsonian Institution’s new National Air and Space Museum (NASM) Udvar Hazy Annex at Dulles International Airport, and Goodyear agreed to assist in funding the construction of a hangar in which to house the airship. In 2001, the ship’s duraluminum structure was carefully dismantled and shipped in large transport planes to Dulles Airport, where she was reassembled, with new materials replacing the decayed and decaying materials of the gas cells and outer envelope. In 2005, she was reopened to the public.
Today, 803 foot-long airship is the centerpiece of the huge Lighter than Air Exhibit at the Smithsonian’s Udvar Hazy complex, and receives millions of visitors annually. Although visitors to the Smithsonian complex can see her from the exterior free of charge, tours of her interior are handled by the Goodyear public relations department and range in cost from $10 dollars per person for a brisk 1 hour walk through her passenger spaces to $250 per person 4-hour group tour exploring the ships entire structure. This culminates in a meal served in the ship’s dining room, accompanied by music played on a replica of the ship’s aluminum grand piano. Longer overnight “airship experience” or period-piece “mystery in the air” experiences are provided to groups upon request.
As requested by the German government, the ship has been reconstructed inside and out as the civil Hindenburg. At Germany’s insistence, however, she does not sport the original huge swastika flags on her fins. Many people, such as various human rights groups, supported this decision. This was not universally popular, however. Some NASM staff and others in the preservation community strongly believe the swastikas were necessary to present the ship in its historically accurate context. For a while, it appeared that this controversy might even derail the whole restoration project. Eventually, however, a compromise was reached eliminating the Nazi flags from the ship, but allowing accurate Nazi emblems on all photographs, travel posters, brochures, tableware, crew uniforms, and other small items accompanying the airship’s exhibit, providing that no replica items offered for sale in the museum’s gift shops contained swastikas or other Nazi emblems.
Hindenburg is usually hung from the hangar in a non-inflated state, but occasionally her cells are inflated with an inert mixture of nitrogen and helium to check for rips and tears in the gas cells skin. She hangs beside a 1/10 cutaway scale model (still almost 100 feet long) depicting her in her wartime US Navy guise. Several restored hook-on aircraft ranging from one of USS Akron’s original F9C Sparrowhawks, to an experimental ASW Osprey are also part of the exhibit, as well as large scale models of other US Navy and foreign airships. All internal passenger spaces have been painstakingly replicated as they would have appeared in 1939. Open for public tours during the museum’s regular hours, and also available for special events and dinners, she is the single most popular exhibit in the entire Smithsonian collection.
From time to time, representatives in Congress or the German Bundestag put forward resolutions that the airship 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 with minimal additional work.
However, this is strongly rejected by historic preservationists and aviation safety experts on both sides of the Atlantic. In the airship’s current restored condition, she completely lacks modern avionics and safety systems required for FAA approval, and the installation of such equipment would impair her historic integrity as a museum exhibit. Even if she could be flown, there are no longer enough people still alive with the training to safely operate her in the air or handle her on the ground, making any attempt to fly her incredibly risky.
Times have changed. Technologies have changed. It is remotely possible that Hindenburg 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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A Surprising Gift
When the European War broke out on September 1, 1939, the German Zeppelin airliner LZ-129 Hindenburg had just completed its final westbound crossing of the North Atlantic season and was being serviced at the Lakehurst Air Dock. The outbreak of war complicated matters for the Deutsche Zeppelin-Reederei, her German operators. The majority of the ship’s east-bound passengers (33) were Americans, most of whom had cancelled their reservations due to the war. Of necessity, the Hindenburg’s return voyage to Germany would take it over French or British airspace, or areas the two Allied powers dominated. Because of a belief (later borne out in captured Luftwaffe documents) that the Hindenburg and its sister Graf Zeppelin II had been used earlier in 1939 to probe British air defenses under the guise of civilian training flights, neither Allied nation would guarantee the airship’s safety.
As with German steamships trapped in US ports and unable or unwilling to attempt a return to Germany, the Hindenburg was interned by the United States. The airship reigned at Lakehurst as a hangar queen until February, 1940, when the United States Navy offered to purchase the ship from the Deutsche Zeppelin-Reederei for a nominal sum of $50,000, which was a tiny fraction of the ship’s original cost. This offer was made, not so much to procure another operational rigid airship for the Navy, but to remove the zeppelin from Hangar 1 at Lakehurst and make room for the Navy’s small fleet of non-rigid airships. Somewhat surprisingly, the Nazi government accepted the offer, requesting only that the ship would not be based in the Atlantic or transferred to any Allied nation. The Germans apparently believed 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.
Preparing for Navy Service
Initially the Navy intended simply to scrap the ex-German ship. Ever since the loss of the USS Macon in 1935, the Navy had no rigid airships, and had no serious plans to purchase any more. However, the Navy’s Bureau of Aeronautics (BuAer) had continued to scheme possible new airships, ending in the “ZRN” proposals of 1939 for a modest 3,000,000 cubic foot training airship to further explore the operation of aircraft from rigid airships. Given that the Hindenburg had essentially been dropped into the Navy’s lap free of charge, BuAer successfully argued that it would be foolish to look such a gift in the mouth. The infrastructure and trained personnel still existed to maintain and operate rigid airships, and the cost of refitting Hindenburg as a naval airship would be miniscule compared to the cost to design and build an entirely new ship. The flying aircraft carrier concept embodied in the USS Akron and Macon was resurrected and the large Hindenburg would be a much larger laboratory to put it in operation, than the proposed ZRN. In June the now-unnamed airship was flown to Goodyear-Zeppelin’s Airdock at Akron for conversion.
The first task involved converting the ship for helium use. This was not as easy as it might seem, because helium has significantly less lifting power than hydrogen. Not only must the structure of the ship be lightened, heavy water-recovery apparatus needed to be installed near the engine cars to replenish water ballast, since the expensive helium could not simply be valved off to compensate for fuel use. Without conversion, the Hindenburg would be militarily useless, even as a training airship.
The main area where the structure of the ship could be significantly lightened without affecting its structural strength was by reducing or eliminating altogether the spacious and relatively luxurious internal passenger bay. Not only would this lighten the structure, it would allow for an increase in the hull volume devoted to lifting gas. BuAer and the Goodyear engineers also saw this as an opportunity to explore various options for stowing and launching airplanes. Initially, two schemes were considered.
Option 1 involved a conversion of the airship’s passenger accommodation bay to house an airplane hangar. This was essentially a duplication of the scheme used on the ill-fated USS Akron and USS Macon and was seen as the quickest conversion. Weight would be reduced by reduction in size of the former passenger bay and the elimination of the internal partitions and facilities associated with the passenger amenities, but the space devoted to lifting gas would not be substantially enlarged. It was calculated that two aircraft equivalent in size and weight to an SBD Dauntless could be maintained in the hangar, with an additional one perched as necessary on a supplemental exterior trapeze attached to the lower keel aft of the hangar. This would, however, require cutting a hangar opening on the ship’s lower keel between two mainframes – introducing possible structural weakness.
Option 2 would exhibit the same aircraft handling accommodations as the first option, but to improve the airship’s useful lift, a new bay and gas cell would be added behind the hangar. Although this option would allow at least two additional airplanes to be routinely carried by the ship, it was by far the most costly and time-consuming, requiring as it would extensive surgery on the ship’s hull. This option also retained the problematic hangar opening through the main keel.
The approach finally implemented was based on an unsolicited proposal prepared by Consolidated Aviation, a firm that had previously focused on providing the Navy with flying boats and floatplanes. Seeking to expand its market, Consolidated had previously prepared a series of patents for aircraft handling and stowage on large rigid airships similar in basic design to the Hindenburg. Although BuAer had not requested outside proposals, Consolidated’s proposal was developed into a series of design sketches by BuAer’s C.P. Burgess. This design eliminated the airship’s interior hangar space altogether to increase useful lift and added a lightly framed exterior “maintenance deck” below the main hull just aft of the control car. This scheme retained the integrity of the lower main keel. The “maintenance deck” would not house any aircraft on a regular basis. Four planes would be stowed semi-externally on individual trapeze stations along the main keel, but for servicing and bombing up they could be temporarily landed in the small maintenance deck one at a time. Planes could also be launched from the deck, meaning that, in an emergency, the reconstructed airship could carry up to five aircraft.
Elimination of an internal airplane hangar and its replacement by a series of semi-external trapeze stations along the lower keel was a key feature of the stillborn ZRCV-class considered by BuAer in 1938, further making this design attractive to US Navy airshipmen.
Another problem resulting from Hindenburg’s conversion to helium was never fully resolved. This was the difficulty in maintaining equilibrium during the operation of the hook-on aircraft.
“Flying” an airship of any kind effectively requires managing a careful balance between the lift provided by the hydrogen or helium lifting gas and the weight of consumable stores, such as fuel, ballast, and so forth. As ballast is dropped or fuel is expended, an airship will rise unless lifting gas is valved off or other mechanical or aerodynamic forces can be applied to push the ship downward.
In an airship using hydrogen, valving gas is an efficient measure to maintain equilibrium, because the gas is relatively inexpensive and easily produced. Helium, in the 1940’s, was still a very rare and very expensive commodity, and the valving of helium from Naval airships was strongly discouraged, except in an emergency.
In the 1930’s, Naval airships were fitted with expensive water recovery apparatus to collect water ballast from engine exhausts. The Akron and Macon were also provided with swiveling propellers that could be directed in a manner to help counteract an airships static lift. On the modified Hindenburg, water recovery apparatus would work reasonably well for routine flight, but the release of hook-on aircraft, each weighing a ton or more, was a significant and virtually instantaneous weight change. The aircraft-carrying Akron and Macon managed this fairly well because of their outriggers with swiveling propellers and the very slow rate with which the extremely small and light F9C fighters were be deployed from their internal hangars.
The Hindenburg, however would be able to release its five hook-on planes virtually instantaneously, and these more modern airplanes would be significantly heavier. Even when flying nose-down at a high speed to provide negative aerodynamic lift during aircraft launching operations, the only way Hindenburg could manage this problem during a sortie of up to a week’s duration without valving off an excessive amount of Helium, was by limiting flight operations to a relatively few aircraft at a time, with long intervals between air operations in which ballast was recovered by the recovery equipment or by low level siphoning of seawater aboard.
Conversion of the former Hindenburg was completed in September 1940, and upon her return flight to Lakehurst she was christened USS Bismarck. As requested by Germany, the airship was not assigned to a fleet unit. She was designated ZRN-1 and initially deployed at Sunnyvale NAS in California as a training airship. This name Bismarck, somewhat odd for a US ship in 1940, was ostensibly in honor of the capital of North Dakota, but there is anecdotal evidence it was indeed a deliberate double entendre to reflect the ship’s German origins. Probably because of the increasing unpopularity of Germany in the 1940-41 period, the name “Bismarck” was rarely used in official correspondence, communiques, or public press releases.
Over the next year, under the command of Lt. Commander Herbert Wiley, who had commanded USS Macon previously, ZRN-1 operated out of Sunnyvale, conducting several long-distance flights to Hawaii, Dutch Harbor, Guam, Midway, and the Philippines to assess the ship’s suitability as a long-range strategic scout and transport as well as her ability to operate from remote and relatively limited ground facilities. The ship was also employed in several fleet problems as well as anti-submarine and air-sea rescue exercises. These tended to show that the zeppelin was much more effective operating on solitary ASW patrols or in strategic reconnaissance than close operations with the fleet – something that veterans of the fleet problems of 1931-1935 would have known. Building on Wiley’s experience with USS Macon, ZRN-1 and her crew became adept at using the ship’s hook-on aircraft and RDF equipment to scout vast expanses of sea and, on one occasion, discover and render assistance to a foundering fishing vessel west of Hawaii. By November 1941, even previous opponents of the rigid airship in Navy service acknowledged the utility of ZRN-1, especially in anti-submarine work and for long range maritime reconnaissance.
During the training exercises ZRN-1 experimented with a variety of aircraft, suitably modified for operations from the ship’s trapezes. This included O2SU Kingfishers (both with and without floats), F3A and F4F fighters, SBD attack planes, and – most interestingly – twin engined Grumman Goose floatplanes, and the experimental Grumman XF5F twin engined fighter to determine the size and weight of airplanes that could reliably be landed and launched from the trapeze stations along the lower keel. Eventually, 15 specially lightened F4F Wildcat fighters and SBD Dauntless bombers were ordered by the Navy for service operation from the airship. The airship also trained a cadre of 15 pilots experienced in the operation of hook-on aircraft as its HTA (Heavier than Air) unit, including several who had earlier flown F9C Sparrowhawks from USS Macon. The airship eventually trained two separate crews, allowing men to be rotated between shore and air duty without fatigue.
Wartime Operations
Following the German declaration of War in December 1941, the airship was put into active service and deployed to Lakehurst to assist in convoy escort and anti-submarine work in the North Atlantic. With this change in function, she was also redesignated an “airship aircraft carrier” (ZRCV)and given the new designator “ZRCV-1.” Thanks to her semi-exterior “maintenance deck” and trapeze stations along her keel she could operate a much wider variety of aircraft than the earlier Akron and Macon type, including attack aircraft. She was also renamed USS Belleau Wood, a name that also had German connotations, but of a nature far more suitable to a warship of the US Navy engaged in combat with Germany. Her usual flight complement consisted of five lightened Douglass SBD Dauntless scout/attack planes. As with the earlier F9Cs operated from USS Macon, the landing gear and their retraction mechanisms were removed, they were unarmored, lacked self-sealing fuel tanks, and were not equipped with defensive machine guns. From 1941 through 1943 she was based at Lakehurst, although on occasion she deployed to temporary facilities in Iceland or Puerto Rico. Because of Japan’s effective and aggressive naval air arm, no consideration was ever given to her deployment in the Pacific. Later, in 1944-45, she was often based out of Bartolomeu de Gusmão, Brazil, which had a large airship hanger originally built to house and service the Hindenburg on its South American service, and so was ideally suited to the American airship.
It is probably not an exaggeration to say that USS Belleau Wood proved that rigid airships could have been an important weapon in the Battle of the Atlantic had more than one of them been available. She and her 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.
However, it was also discovered that the airship (both rigid and non-rigid) was really not ideally suited to close convoy escort. Airships were highly visible from a surfaced submarine at long distances. This frequently allowed submarines to locate and converge on convoys under close airship escort in situations where the merchants might otherwise have gone unnoticed. Also, the close proximity of a visible airship to convoys at times had the opposite, equally unhelpful effect, of making a submarine abort a possible attack when effective escorts were present that could destroy the U-boat.
As a result, the operating doctrine for Belleau Wood shifted away from close escort to independent patrol focused on the discovery and destruction of U-boats. This was particularly her role in the mid-Atlantic “gap” outside the range and endurance of most shore-based ASW aircraft. Also, she could conduct sweeps and patrols at night and in poor visibility conditions that grounded many carrier aircraft. The airship could also operate her aircraft when rough sea conditions made operations from small escort carriers problematic. As patrol vessels, the zeppelin’s relatively high speed in comparison to surface ships and extremely high endurance in comparison with fixed-wing aircraft played real dividends.
From 1943 Belleau Wood was equipped with the air/sea search radars, towed and buoy sonar and hydrophones, and magnetic anomaly detection (MAD) equipment. Although her weapon payload was limited, she or her aircraft could deploy a small number of depth bombs, standard bombs, and other anti-ship weapons. Toward the end of the war, acoustic homing torpedoes were added to this arsenal. Because of the additional weight, her compliment of aircraft was reduced to two hook-on aircraft in 1944-45. Nonethless, the airship was more than capable of both finding submarines and pressing home attacks.
Because of her long flight endurance, Belleau Wood could loiter on ASW searches in the “gap” for up to a week, and although her specially modified and lightened 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 to some extent by the airship while on station. For these reasons, being located, tracked, and engaged by a rigid airship was one of a U-boat commander’s worst nightmares. Belleau Wood’s log records one confirmed and three probable U-boat sinkings.
In addition, on one occasion, Belleau Wood was even successful in capturing a German submarine. A detailed description of this action was recorded by KM Kapitanleutnant Heinrich Zahler, who surrendered his damaged U-554 to the airship on March 12, 1945:
We were returning from patrol off the coast of Brazil when, at 0900, we saw two small planes of the Douglas type 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 two 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 two distant depth bomb explosions. By now our remaining battery power was becoming critically low. It was obvious we would not shake our pursuer, so 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 two airplanes who strafed the ship with machine guns and rockets.
We succeeded in destroying one plane and driving off the other, but all topside guns were 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 could not bottom but disengaged the screws and 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 further 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. The airship took station approximately 150 meters over us. Although I intended to scuttle U-554 once everyone was off, several armed American sailors rappelled down from the zeppelin 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 me and 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 our submarine. 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)
This action resulted in the Bellau Wood’s company being awarded a Battle Star. Her Captain, Lt. Commander John Mansfield and Executive Officer, William T. Jane, Jr., were awarded the Silver Star. Several other crewmembers received Bronze Stars.
Prior to mid-1944, Belleau Wood only operated within its out-and back radius of action (roughly 3500 miles) of Lakehurst or Brazil. As a former transatlantic airliner fully capable of transatlantic convoy escort or patrol 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. On only one occasion was the airship engaged by a German aircraft – a long range Ju 290 maritime reconnaissance plane she happened to encounter in the Bay of Biscay. Visibility conditions were relatively poor and the action was inconclusive. The Junkers made one pass at the airship spraying her randomly with machine gun fire to no effect, while the airship’s own .50 cal. machine guns mounted in her control and engine cars were equally ineffective. Lacking any fighters on board, Belleau Wood launched two unarmed SBDs, hoping this would scare off the German aircraft. Although the airship’s log credits the SBDs with driving off the German, it is much more likely the Ju 290 merely broke off the chance engagement because of the poor visibility.
Somewhat unexpectedly, the rigid airship proved to be less vulnerable to damage from submarines’ deck guns than had been feared. USS Belleau Wood was fired upon by surfaced submarines on a number of occasions. Standard HE and AP rounds would often pass through the airship’s envelope with negligible damage or gas loss. Unless a lucky hit was made on the control stations, engines, critical structural members, or fuel systems, a large rigid airship was virtually invulnerable to the standard anti-aircraft armament shipped by wartime U-boats. Even when such hits were made on Belleau Wood, the ship never came close to destruction. At one time or another the airship returned to base with 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.
Belleau Wood’s successes in the anti-submarine role were not lost on the Navy, and in 1943, BuAer initiated design studies for a specialized ASW airship considerably larger and more capable than the modified Hindenburg. Designated the ZRCV-ASW, these plans called for a 10,000,000 cubic foot airship fitted with a complete array of ASW sensors and weapons, together with a squadron of as many as eight dedicated ASW aircraft. However, time had passed the rigid airship by.
The following 1943 congressional testimony from Admiral Ernest J. King regarding the new airships sums up the situation well:
The Belleau Wood has proved to be extremely useful against the German u-boats. I was a proponent of rigid airships during the 1930’s and am glad we have one working with the Atlantic Fleet now. However, I do not see us building any more of them. Such vessels would represent a dangerous diversion of resources from what the Navy really needs: more effective combat ships, fleet oilers, and airplanes. For the cost of one new airship, we could build several destroyer escorts and as many as 15 anti-submarine long range patrol planes. We need those ships and planes far more than we need several more large airships, despite their unique abilities.”
Death and Resurrection
USS Belleau Wood served until the end of the War and was retained in flight status as a US Navy recruitment tool until 1947. She was decommissioned in 1948 and after desultory attempts by the Navy to interest various US and foreign commercial operators in the ship, the Navy transferred her to the Goodyear Corporation, whose chairman, Paul Lichtfield, remained an advocate for rigid airships in commerce and even military applications. Now unnamed, the ship was flown to Akron, Ohio, and laid up in the old Goodyear-Zeppelin Airdock while Goodyear developed plans for her operation, both in public relations and research. She occasionally flew to evaluate various schemes for “future airships”, including even the installation of a dummy “atomic power plant” within her hull to evaluate the feasibility of mounting such a power plant in rigid airships.
Nothing came of these plans, however, and by 1955, the airship served only as a non-flying “flagship” of Goodyear’s fleet of blimps and as a local tourist attraction. In this role, the airship survived as a poorly maintained relic occupying space the hangar until the late 1970’s. In 1979, Goodyear sought to use its giant hangar for other purposes, and offered the ship for donation to the Smithsonian Institution or other flight museums around the nation. In 1980, after a survey of the ship’s rings and longitudinal girders showed the hull retained enough integrity to permit full reconstruction, the airship was placed on the National Register of Historic Places as a unique technological reminder of the rigid airship era.
Also, as early as 1976, airship enthusiasts on both sides of the Atlantic had been lobbying Goodyear and the US Government for her reconstruction and preservation as a museum ship, and continuing threats of possible demolition gave them further ammunition.
The ship and its final status remained in limbo for almost twenty years until, 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 provide funding 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. A space was found at the Smithsonian Institution’s new National Air and Space Museum (NASM) Udvar Hazy Annex at Dulles International Airport, and Goodyear agreed to assist in funding the construction of a hangar in which to house the airship. In 2001, the ship’s duraluminum structure was carefully dismantled and shipped in large transport planes to Dulles Airport, where she was reassembled, with new materials replacing the decayed and decaying materials of the gas cells and outer envelope. In 2005, she was reopened to the public.
Today, 803 foot-long airship is the centerpiece of the huge Lighter than Air Exhibit at the Smithsonian’s Udvar Hazy complex, and receives millions of visitors annually. Although visitors to the Smithsonian complex can see her from the exterior free of charge, tours of her interior are handled by the Goodyear public relations department and range in cost from $10 dollars per person for a brisk 1 hour walk through her passenger spaces to $250 per person 4-hour group tour exploring the ships entire structure. This culminates in a meal served in the ship’s dining room, accompanied by music played on a replica of the ship’s aluminum grand piano. Longer overnight “airship experience” or period-piece “mystery in the air” experiences are provided to groups upon request.
As requested by the German government, the ship has been reconstructed inside and out as the civil Hindenburg. At Germany’s insistence, however, she does not sport the original huge swastika flags on her fins. Many people, such as various human rights groups, supported this decision. This was not universally popular, however. Some NASM staff and others in the preservation community strongly believe the swastikas were necessary to present the ship in its historically accurate context. For a while, it appeared that this controversy might even derail the whole restoration project. Eventually, however, a compromise was reached eliminating the Nazi flags from the ship, but allowing accurate Nazi emblems on all photographs, travel posters, brochures, tableware, crew uniforms, and other small items accompanying the airship’s exhibit, providing that no replica items offered for sale in the museum’s gift shops contained swastikas or other Nazi emblems.
Hindenburg is usually hung from the hangar in a non-inflated state, but occasionally her cells are inflated with an inert mixture of nitrogen and helium to check for rips and tears in the gas cells skin. She hangs beside a 1/10 cutaway scale model (still almost 100 feet long) depicting her in her wartime US Navy guise. Several restored hook-on aircraft ranging from one of USS Akron’s original F9C Sparrowhawks, to an experimental ASW Osprey are also part of the exhibit, as well as large scale models of other US Navy and foreign airships. All internal passenger spaces have been painstakingly replicated as they would have appeared in 1939. Open for public tours during the museum’s regular hours, and also available for special events and dinners, she is the single most popular exhibit in the entire Smithsonian collection.
From time to time, representatives in Congress or the German Bundestag put forward resolutions that the airship 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 with minimal additional work.
However, this is strongly rejected by historic preservationists and aviation safety experts on both sides of the Atlantic. In the airship’s current restored condition, she completely lacks modern avionics and safety systems required for FAA approval, and the installation of such equipment would impair her historic integrity as a museum exhibit. Even if she could be flown, there are no longer enough people still alive with the training to safely operate her in the air or handle her on the ground, making any attempt to fly her incredibly risky.
Times have changed. Technologies have changed. It is remotely possible that Hindenburg 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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