The Hindenburg was filled with hydrogen, the lightest element in existence and a gas that burns violently when mixed with air. Germany chose hydrogen not because it was ideal but because the only realistic alternative, helium, was effectively off-limits. The United States held a near-monopoly on the world’s helium supply and refused to sell it to Nazi Germany, leaving the Zeppelin Company with a gas it knew was dangerous but had no practical way to replace.
The Helium Problem
Helium would have been the safer choice, and the Zeppelin Company knew it. Hugo Eckener, the chairman of the company and the most experienced airship commander alive, wanted helium for the Hindenburg from the start. Helium is completely nonflammable. It is also the second lightest element, which makes it an effective lifting gas, though not quite as effective as hydrogen. The problem was not engineering preference. The problem was geopolitics.
In the early twentieth century, the United States produced virtually all of the world’s commercial helium, extracted from natural gas fields in Texas, Kansas, and Oklahoma. The U.S. government treated helium as a strategic military resource. The Helium Act of 1925 established federal control over helium production and banned its export, with narrow exceptions that required government approval. By the time the Hindenburg was being designed in the mid-1930s, Adolf Hitler had come to power, and the political appetite in Washington for selling a militarily useful gas to Nazi Germany was nonexistent. Secretary of the Interior Harold Ickes was particularly opposed to any helium sale to Germany, and the export was never approved.
The Zeppelin Company had actually designed the Hindenburg with helium in mind. The airship’s internal gas cells were sized and structured to accommodate helium, which provides less lift per volume than hydrogen. When it became clear that helium would not be forthcoming, the engineers modified the design to use hydrogen instead, adjusting the amount of lifting gas and payload calculations accordingly. This was not an unusual compromise for German airship builders. Every rigid airship Germany had ever flown, from the earliest Zeppelins in the 1900s through the Graf Zeppelin that circled the globe in 1929, had used hydrogen. The Germans had decades of experience handling it. They considered it manageable, if not ideal.
Why Hydrogen Works as a Lifting Gas
Hydrogen’s appeal as a lifting gas comes down to basic physics. An airship floats for the same reason a hot-air balloon does: the gas inside is less dense than the surrounding atmosphere, creating buoyancy. Hydrogen is the lightest gas that exists, with roughly half the density of helium and about fourteen times lighter than air at sea level. That density difference translates directly into how much weight an airship can carry. A given volume of hydrogen can lift about eight percent more than the same volume of helium. For an airship the size of the Hindenburg, which stretched over 800 feet long and held about 7 million cubic feet of gas, that difference added up to several extra tons of useful payload.
Hydrogen was also far cheaper and easier to produce than helium. While helium had to be painstakingly separated from natural gas deposits found in only a few places on Earth, hydrogen could be manufactured through straightforward industrial processes: passing steam over hot iron, reacting acids with metals, or electrolyzing water. Germany had abundant capacity for hydrogen production. Even today, the cost difference between the two gases remains stark, and researchers have pointed out that many modern airship concepts are held back by the high price of helium.1ResearchGate. Hydrogen Airships: A Necessary Return Because of High Costs of Helium In the 1930s, with no access to American helium, hydrogen was not just the cheaper option. It was the only option.
How the Zeppelin Company Managed the Risk
The Germans were not cavalier about putting a flammable gas inside their airships. Hydrogen is extremely flammable, with a wide range of concentrations in air that can ignite, and it burns with an almost invisible flame. The Zeppelin Company had been building and operating hydrogen airships for nearly four decades before the Hindenburg, and they had developed an elaborate set of safety protocols to reduce the risk of fire.
Inside the Hindenburg, the hydrogen was not stored in a single open space. It was divided among sixteen individual gas cells made from multiple layers of cotton fabric lined with a gelatin-latex membrane to minimize gas leakage. The cells were separated from each other and from the outer hull. Crew members routinely inspected the cells for leaks, and the airship’s ventilation system was designed to prevent hydrogen from accumulating in the spaces between cells and the outer cover. Electrical systems were bonded and grounded to prevent static discharge. Smoking was completely prohibited except in a single pressurized smoking lounge with an airlock-style double door and its own separate ventilation, designed to keep any open flame completely isolated from the hydrogen above.
These precautions worked, for a time. The Hindenburg completed ten round trips across the Atlantic in 1936, its first year of commercial service, carrying passengers in a level of luxury that rivaled ocean liners. The Graf Zeppelin had made hundreds of flights over nearly a decade without a hydrogen fire. The safety record of German commercial airships was, by the standards of 1930s aviation, remarkably good. That record ended on May 6, 1937.
What Happened at Lakehurst
The Hindenburg arrived at Naval Air Station Lakehurst, New Jersey, on the evening of May 6, 1937, completing its first northbound transatlantic crossing of the season. The landing had already been delayed by several hours because of thunderstorms in the area. Captain Max Pruss brought the airship in for a high landing approach around 7:00 p.m., and ground crews caught the mooring lines dropped from the bow. Then, at 7:25 p.m., witnesses saw a small burst of flame near the tail of the airship. Within about thirty-four seconds, the entire ship was engulfed.
The fire killed thirty-five of the ninety-seven people on board and one member of the ground crew. That sixty-two people survived is itself remarkable, given how quickly the ship was consumed. Many passengers in the forward sections survived by jumping from the gondola windows as the burning tail section sank and the bow rose briefly upward. The disaster was captured on film and in Herbert Morrison’s famous radio broadcast, whose anguished narration (“Oh, the humanity!”) seared the image into public memory in a way that no previous aviation accident had been.
The exact cause of the initial ignition has never been definitively established. The most widely accepted explanation, supported by the official investigations conducted by both the United States and Germany at the time, is that a hydrogen leak developed near the stern, possibly caused by a bracing wire that snapped and tore a gas cell. The leaking hydrogen then mixed with air and was ignited by a spark, likely from the buildup and discharge of static electricity in the atmosphere. The airship had been flying through moist, electrically charged air from the earlier thunderstorms, and the mooring lines, when dropped, may have grounded part of the ship’s frame while other parts remained at a different electrical potential. That difference could have produced a spark.
Sabotage was also investigated and never entirely ruled out, but no physical evidence of a bomb or incendiary device was found, and the sabotage theory has remained speculative.
The Outer Skin Debate
In the 1990s, a retired NASA engineer named Addison Bain proposed a different explanation for the Hindenburg fire. Bain argued that the airship’s outer covering, which was treated with a coating of cellulose acetate butyrate doped with aluminum and iron oxide powders to weatherproof and tighten it, was the primary fuel for the fire. He pointed out that the combination of aluminum powder and iron oxide is essentially thermite, a mixture that burns intensely. In Bain’s theory, the hydrogen was secondary. The real culprit was the skin itself, which ignited first and burned so rapidly that even helium-filled versions of the airship would have been destroyed.
This “incendiary paint theory” got significant media attention and was popularized in documentaries, but it has not held up well under scrutiny. The concentration of aluminum and iron oxide in the Hindenburg’s doping compound was far too low to sustain a thermite reaction. Thermite requires a very specific ratio of finely powdered aluminum and iron oxide in close contact, and the Hindenburg’s coating did not come close to that ratio. More directly, analysis of the burn pattern and the speed of the fire is consistent with a hydrogen fire propagating through gas cells, not a surface fire spreading along the fabric. The hydrogen inside the ship, at roughly 7 million cubic feet, represented an enormous store of chemical energy. The skin, by comparison, represented a relatively small amount of fuel.
Most historians and combustion experts who have examined the evidence agree that hydrogen was the primary fuel. That does not mean the outer covering played no role at all. The doped fabric likely contributed to the intensity of the blaze and the dramatic visual appearance of the flames. But without the hydrogen, the fire would not have consumed the ship in half a minute. The incendiary paint theory is one of those ideas that sounds plausible in a documentary but does not survive contact with the chemistry.
Why the Disaster Ended the Airship Era
The Hindenburg was not the first airship destroyed by a hydrogen fire. Dozens of military and civilian airships had been lost to fire, structural failure, and weather in the preceding decades. Britain’s R101 had crashed and burned in 1930, killing 48 people. The U.S. Navy’s helium-filled USS Akron went down in a storm in 1933, killing 73 of 76 aboard, and its sister ship the Macon was lost in 1935. Airship disasters were not new. What was new about the Hindenburg was that cameras were rolling.
The Lakehurst disaster was one of the first major catastrophes captured on film and broadcast to a mass audience. Newsreel footage showed the enormous ship collapsing in flames, and Morrison’s radio recording was replayed across the country. The visual impact was devastating, and it crystallized a public perception that airships were inherently too dangerous for passenger travel. That perception was not entirely fair. The Hindenburg’s safety record up to that point had been excellent, and the Graf Zeppelin had flown more than a million miles without a serious incident. But the image of the burning ship was too powerful to argue against.
The disaster also arrived at a moment when heavier-than-air aircraft were rapidly improving. The Douglas DC-3, which had entered service just a year earlier, could carry passengers across the United States faster and more cheaply than any airship. Flying boats were beginning to cross the Atlantic. The economic case for rigid airships, which were staggeringly expensive to build and operate, was already weakening. The Hindenburg fire did not single-handedly end the airship age, but it delivered the psychological blow that made abandoning the technology easy to justify. Germany’s remaining airship, the Graf Zeppelin II, was grounded and eventually scrapped for its aluminum during World War II. No rigid airship has carried paying passengers since.
Could Helium Have Saved the Hindenburg
If the United States had sold helium to Germany and the Hindenburg had been filled with it, the ship almost certainly would not have burned. Helium cannot catch fire under any circumstances. Whatever ignition source sparked the disaster, whether static electricity, structural failure, or some other cause, it would have had nothing to ignite if the lifting gas had been helium.
That said, helium would not have made the Hindenburg invulnerable. The ship carried diesel fuel for its engines, and its interior was full of flammable materials: furniture, fabric, the doped cotton outer covering. A helium-filled Hindenburg struck by lightning or suffering a catastrophic structural failure could still have been destroyed, just not in the same spectacular fashion. The USS Akron and USS Macon, both filled with helium, were both lost in storms with heavy casualties, demonstrating that the lifting gas was not the only risk an airship faced.
The helium question also had a payload cost. Because helium provides less lift than hydrogen, a helium-filled Hindenburg would have carried fewer passengers and less cargo. Eckener and his engineers had accounted for this in the original design, but the switch to hydrogen after the helium embargo actually gave the ship more useful lift than planned. A helium version would have been somewhat less commercially viable, though still functional.
Hydrogen and Modern Airship Concepts
The Hindenburg disaster made hydrogen a taboo lifting gas for nearly a century, but the conversation has quietly reopened. Helium is a nonrenewable resource, formed by the radioactive decay of heavy elements deep in the Earth’s crust and trapped in a small number of natural gas deposits. The global supply is limited and increasingly expensive. Shortages have periodically disrupted industries that depend on helium, from medical imaging (MRI machines use liquid helium for cooling) to semiconductor manufacturing. Against that backdrop, some engineers and researchers have revisited whether hydrogen, handled with modern materials and safety systems, might be a viable option for lighter-than-air craft.
The economics are compelling. Hydrogen can be produced from water using renewable electricity, making it essentially unlimited in supply. A 2012 analysis comparing helium-filled and hydrogen-filled airship designs found that the high cost of helium was a significant barrier to many proposed airship projects, and that locally produced hydrogen from solar-powered electrolysis could dramatically reduce operating costs.1ResearchGate. Hydrogen Airships: A Necessary Return Because of High Costs of Helium Modern materials, leak detection systems, and fire suppression technologies are vastly improved compared to the 1930s. Some proposals envision hydrogen airships for cargo transport, surveillance, or communications relay in remote areas where the lifting gas’s flammability can be managed more carefully than it could in a passenger-carrying vessel.
None of these proposals has yet resulted in a commercially operating hydrogen airship. The psychological legacy of the Hindenburg remains powerful, and regulators are understandably cautious. But the physics and economics that made hydrogen attractive in the 1930s have not changed, and the helium supply problem has only gotten worse. Whether the airship community eventually overcomes the Hindenburg’s shadow is an open question, but the argument for hydrogen has not disappeared. It has just been waiting.