Myths about the Hindenburg Crash

A fairly typical hydrogen advocate blog, this one by Greg Blencoe

A fairly typical hydrogen blog, this one by Greg Blencoe

Many hydrogen fuel advocates falsely claim that hydrogen was not responsible for the Hindenburg disaster.

In fact, the Hindenburg was just one of dozens of hydrogen airships destroyed by fire as a result of their highly flammable lifting gas.

This page explores and debunks some of the more common myths about the Hindenburg disaster spread by hydrogen fuel advocates, including:

For a shorter discussion of this subject, visit: Photographic Evidence that the Hindenburg was not “Painted with Rocket Fuel”

Hindenburg Myth 1: “The Hindenburg was painted with rocket fuel”

This idea originated with Addison Bain, and comes from the fact that Hindenburg’s fabric covering was doped with a solution that included aluminum powder, and in certain sections iron oxide, which are sometimes used as components in solid rocket fuel.

Hydrogen fire roars around sections of covering which have not yet ignited

Hydrogen fire burning around sections of Hindenburg’s covering, which were not sufficiently flammable to have yet ignited

The Facts

Hindenburg’s cotton-canvas covering was doped to keep it taut for aerodynamic reasons and to protect it from damage from water, wind, and small objects hitting the surface.  The dope was a solution of cellulose acetate butyrate to which aluminum powder had been added.  At the top of the hull, a layer of iron oxide was applied to the inside surface of the covering to protect the fabric from the UV radiation in direct sunlight (see color photo below).

The aluminum powder gave the ship its silvery coloring, but its practical purpose was to reduce the heating effects of the sun, which can cause an airship’s gas cells to expand and release their gas.

While certain rocket fuels contain aluminum powder, that does not mean that everything containing aluminum powder is a rocket fuel.  Aluminum powder has many uses other than rocket fuel, including the manufacture of photovoltaic solar energy panels and metallic paints for cars, boats, furniture, and other items.  And none of these tend to explode.

(As an analogy, butyl rubber [polyisobutylene] is used in both C-4 plastic explosives and basketballs but that doesn’t make your basketball a bomb.)

The chief ingredient in rocket fuel is not aluminum powder but an oxidizer (a substance which creates its own oxygen supply to support combustion) and without an oxidizer, in sufficient quantity, you don’t have rocket fuel.

As explained by the website of NASA’s Kennedy Space Center:

A solid propellant always contains its own oxygen supply. The oxidizer in the Shuttle solids is ammonium perchlorate, which forms 69.93 percent of the mixture. The fuel is a form of powdered aluminum (16 percent), with an iron oxidizer powder (0.07) as a catalyst. The binder that holds the mixture together is polybutadiene acrylic acid acrylonitrile (12.04 percent). In addition, the mixture contains an epoxy-curing agent (1.96 percent). The binder and epoxy also burn as fuel, adding thrust.

The oxidizer is by far the largest component of rocket fuel; approximately 70% in the case of the Space Shuttle, compared to 16% aluminum powder.

Interior of hull of Hindenburg sister ship LZ-130, showing iron oxide (red) applied to inside surface of upper hull, but not to inside of lower hull.  The structure in the center of the photo is the axial corridor, at the center of the ship.

Interior of hull of Hindenburg sister ship LZ-130, showing the iron oxide (red) applied to inside surface of the upper half of the hull, but not the lower half.  Hindenburg was doped the same way, but there are no color photos of its interior.  The structure in the middle of the photo is the axial corridor, at the center of the ship.  (click photo to enlarge)

The only substance in Hindenburg’s doping compound which could conceivably act as an oxidizer was the iron oxide added to one section of the covering, but it was in too small a quantity (one of six layers of dope, or approximately 17%) and was too separated from the aluminum powder to act as an effective oxidizer in this application.  At no point in the doping process were the aluminum powder and iron oxide mixed together, and most of the iron oxide was applied to the inside surface of the fabric of the upper hull (as seen in the photo at right), while the aluminum powder was applied to the outside of the hull.

[For additional technical details regarding the Hindenburg’s covering and “rocket fuel,” see: The Hindenburg Hydrogen Fire: Fatal Flaws in the Addison Bain Incendiary-Paint Theory, A. J. Dessler “Dressler” – download pdf]

Without an oxidizer, even the Space Shuttle would still be fizzling slowly at its launch pad in Florida… just like this theory.

Perhaps the best evidence that the Hindenburg was not painted with “rocket fuel” are the films and photographs of the disaster.  If the Hindenburg had been painted with anything remotely as flammable as rocket fuel, its covering would have burned quickly, and would have been totally devoured by the fire, but that did not happen as you can see from films and photos of the tragedy.

Hindenburg Myth 2: “The Hindenburg was painted with thermite”

Basically a variation on the rocket fuel myth, many people seem to think the Hindenburg was “painted with thermite.”  That’s a dramatic image, and it makes for a great sound bite, so it is easy to see why this myth spread so rapidly.  And since thermite can be made by mixing aluminum powder and iron oxide, and since both substances were used on sections of the Hindenburg’s covering, this myth “seems” to make sense

Unfortunately the truth is a little more boring, and a lot more technical.  While it is true that a thermite reaction can be created by mixing aluminum and iron oxide, it requires a ratio of about 1 part aluminum to 3 parts iron oxide [download pdf]. The dope used on Hindenburg’s silver-colored hull contained 5 parts aluminum to 1 part iron oxide.  In other words, Hindenburg’s dope contained less than 1/10 the amount of iron oxide needed to create a thermite reaction.

In addition, a thermite reaction requires the components to be well blended, and if they separate, the mixture is useless. The aluminum powder and iron oxide on Hindenburg were applied separately, in different layers, and were not mixed together as would be required to create thermite.

But here’s the real clincher:  Since thermite requires 3 parts of heavy iron oxide for every 1 part of light aluminum powder, the designers of a lighter-than-air vehicle would never paint the ship with thermite, not because it can burn, but because it would be too heavy.  If the Hindenburg had really been painted with thermite, it could never have left the ground in the first place.  :-)

In defense of the “thermite theory” Addison Bain refers to what he calls “thermite hot spots” — a few very small small points where he found iron oxide in one layer of dope to have bled through to the layers of aluminum powder — but Bain does not offer any evidence of how widespread this might have been, or any evidence that a significant thermite reaction occurred during the burning of the Hindenburg.

The best evidence that no significant thermite reaction took place are the photographs and films of the fire.  As mentioned above, iron oxide was applied only to the upper portion of the Hindenburg, to protect the covering from the sun’s UV rays.   (The lower part of Hindenburg’s hull was doped only with aluminum, since there was no point in applying the additional weight of iron oxide to a part of the ship not exposed to the sun.) Films of the Hindenburg fire show no difference in the speed at which the upper hull burned as compared to the lower hull.  If the aluminum powder and iron oxide on the upper hull had really created a thermite reaction, the upper hull would have burned much faster than the lower hull, but it didn’t.

In fact, the only lines of demarcation seen in the photographs of the fire are between gas cells, because it was primarily the hydrogen — and not the covering — which was burning.

Gas cells 9 and 10; forward engine car highlighted to show of images. (click to enlarge)

Gas cells 9 and 10; engine car highlighted to show alignment of images. (click to enlarge)

Hindenburg Myth 3: “The Hindenburg’s outer cover was highly flammable”

This is the generalized version of the “rocket fuel” and “thermite” myths. Certain hydrogen advocates have tried to argue that the Hindenburg’s covering was so highly flammable that it was the covering — and not the hydrogen — which was the primary factor in the ship’s rapid destruction.

In fact, the Hindenburg’s covering, while certainly combustible, was not especially flammable and actually burned quite slowly.  Many sections of the covering burned only when exposed to the direct heat of burning hydrogen (as seen in the films and photographs of the disaster) and large areas of the covering never burned at all, indicating that the covering could not have been highly flammable.

hindenburg-bow-torch

Hydrogen flames shoot through the bow, while the surrounding covering has not yet ignited.

As discussed above, Hindenburg’s covering was made of cotton canvas doped with a solution of cellulose acetate butyrate, to which aluminum powder (and in some places iron oxide) had been added.  Canvas doped with cellulose acetate butyrate is combustible but nonflammable; in other words, it will burn if held in a flame, but tends to self-extinguish when removed from heat.  [See, The Hindenburg Fire: Hydrogen or Incendiary Paint?, A. J. Dessler, D. E. Overs, and W. H. Appleby, “Dessler/Overs/Appleby,” pdf available here.)]

Some discussions of the Hindenburg incorrectly claim that the dope contained cellulose nitrate, rather than cellulose acetate. In fact, the designers of Hindenburg deliberately avoided cellulose nitrate precisely because it was known to be flammable, and they chose the safer cellulose acetate instead. The dangers of cellulose nitrate were well understood at the time, since it was used in the first photographic films which were known to be highly flammable. Cellulose acetate filmstock was introduced as an alternative in the 1920s, and was known as “safety film.”

In discussing the flammability of the covering, however, it is important to differentiate between two questions:

  • (A) Whether the covering was sufficiently flammable that it could have been the initial source of ignition.   (i.e., whether the covering could have been ignited by an electrical discharge, and then ignited the hydrogen)

or

  • (B) Whether the covering was so highly flammable that it was the main cause of the destruction of the ship.  (Some hydrogen advocates argue that Hindenburg’s covering was so flammable that the ship would have been destroyed even if it had been inflated with helium, a position repudiated by Addison Bain himself.)

There is some evidence that Hindenburg’s fabric might have been sufficiently flammable to be the initial source of ignition (although that is not likely in the wet and rainy conditions at the time of the crash).  But the covering was not so highly flammable that it was a major factor in the destruction of the airship.

Hydrogen fire roars fore, aft, and a behind a section of covering which has not yet ignited.

Hydrogen burning around a section of the covering which has not yet ignited.

Various scientific tests performed on doped canvas replicating the covering of the Hindenburg show that the covering itself actually burned quite slowly.  In fact, without the presence of hydrogen, the covering would have taken almost 40 hours to burn completely: The upper covering, containing iron oxide plus aluminum, would have taken about 30.9 hours, and the lower covering, containing aluminum alone, would have taken 37.9 hours. (See, Dessler/Overs/Appleby, cited above.)

In fact, Addison Bain’s own experiment with a 2-1/2″ piece of the actual covering of the Hindenburg, shown on the British television program Secrets of the Dead, What Happened to the Hindenburg, shows that it would have taken approximately 40 hours for the Hindenburg’s covering to burn. (Cited in Dessler/Overs/Appleby.)

Even the television show Mythbusters declared this myth as busted.

And you can see for yourself that the Hindenburg’s covering was anything but highly flammable. Photographs of the wreckage show that even after a fire so intense that it destroyed an 800-foot airship in about 34 seconds, sections of the covering still remained unburned.

covering-unburned

Wreckage of the Hindenburg. (click to enlarge)

If the Hindenburg had been inflated with helium rather than hydrogen, even if the fabric ignited as the result of an electrical discharge, the small resulting fire would not have been a major catastrophe, and there would have been many hours available for a safe and orderly evacuation.

Hindenburg Myth 4: “Hydrogen burns without color so the flames could not have been hydrogen burning”

This myth contends that since hydrogen burns with a mostly invisible flame, and since the Hindenburg’s flames were red or orange, it could not have been the hydrogen that was burning.

Many proponents of the “inflammable paint” myth try to illustrate their argument by showing color photograph of the Hindenburg on fire with a bright orange flame:

Digitally colorized photograph of Hindenburg from website of the National Hydrogen Association

Photograph from website of the National Hydrogen Association

But in fact these are all colorized photographs, since no color photographs were taken of the Hindenburg disaster.  And whoever added the color could just as easily have made the flames pink, purple, or green:

Or...

The same photograph colorized green.

(The only legitimate color photographs of the Hindenburg disaster were Kodachrome photos taken after the crash, which show the wreckage on the ground after all the hydrogen had burned off.)

So if anyone shows you a “color photo” of the Hindenburg disaster to support a theory about the cause or progress of the fire, just chuckle at them sympathetically.

But the original black & white photographs do show flames that are clearly visible, and it is true that hydrogen burns with a mostly invisible flame, so how can that be?

Here’s the simple explanation: Hydrogen does burn invisibly… but only when hydrogen is the only thing burning.

As the Hindenburg was consumed by flame, it was not only the hydrogen which burned; it was also the canvas covering, the aluminum alloy framework, the steel bracing cables, the gelatine-cotton gas cells, the tanks of diesel fuel, and even the tables and chairs. And no-one has ever claimed that canvas, aluminum, steel, or diesel fuel burns with an invisible flame.

In addition, not only did the rest of the Hindenburg’s components emit color and light as they burned, but they also acted as a mantle. A “mantle” is the part of a gas lamp that glows to emit light. Most flammable gases burn without color, which is why gas lanterns always use a mantle; the gas burns and creates heat, but it is the mantle which glows and emits light.  The aluminum girders and steel bracing wires of the Hindenburg were the largest mantle in gas lamp history.

The Ultimate Reality Check:

Dozens of hydrogen-inflated airships other than the Hindenburg also exploded or burned, including German zeppelins which were shot down over England during WWI, and all burned with brightly visible flames — just like the Hindenburg.

Hindenburg Myth 5: “People on the Hindenburg were not injured by the hydrogen”

This is probably the most absurd myth about the Hindenburg disaster, yet it is frequently promoted by hydrogen fuel advocates.

Whatever caused the initial ignition of the Hindenburg fire, the airship was incinerated in less than a minute — and came crashing to the ground as smoldering wreckage — because virtually the entire space of the ship’s 800-foot hull was filled with highly flammable hydrogen.  Yet many hydrogen fuel advocates insist that the millions of cubic feet of hydrogen in Hindenburg’s gas cells (representing, according to Addison Bain’s own estimate, over a billion BTUs of energy) somehow had no effect on the ship’s passengers and crew when it burned.

Hindenburg_burning-web

The Claims of the Hydrogen Advocates

The newsletter of the American Hydrogen Association informed its readers: “No deaths were due to the hydrogen fire that was ultimately ignited by the burning skin of the Hindenburg.” [Hydrogen Today, vol. 10, no. 2, 1999, p.8 – download pdf]

According to the Association’s website:

Hydrogen is about fifteen-times lighter than air. After ignition by the violently burning surface varnish, flames from hydrogen combustion traveled upward, far away from the crew and passengers in the cabins below. What fell to the ground with the passengers were burning shrouds from the exterior fabric, a large inventory of diesel fuel, and combustible materials that were in the cabins…

Sixty-two persons from the Hindenburg lived through the disaster by being fortunate enough to ride the Hindenburg down and escape the flames and wreckage that fell to the ground. Many of these survivors were relatively unharmed.

Dr. Karl Kruszelnicki, an Australian hydrogen advocate who is a popular television science expert known as “Dr. Karl,” has gone so far as to claim that the Hindenburg’s hydrogen was not only “totally innocent,” but did not even contribute to the ensuing fire:

In all of this, the hydrogen was innocent. In the terrible disaster, the Hindenburg burnt with a red flame. But hydrogen burns with an almost invisible bluish flame. In the Hindenburg disaster, as soon as the hydrogen bladders were opened by the flames, the hydrogen inside would have escaped up and away from the burning airship – and it would not have not contributed to the ensuing fire. The hydrogen was totally innocent.

[Dr. Karl’s complete article is rebutted here.]

Hydrogen advocate Greg Blencoe from the company Hydrogen Discoveries claims:

The clean hydrogen flames [emphasis added] swirled above the occupants of the passenger compartment, and all those who rode the airship down to the ground survived. Thirty-five of the thirty-seven casualties perished from jumping to the ground, and most other injuries resulted from diesel burns.

blencoe-blog

[Contrary to Blencoe’s inaccurate statement, “all those who rode the airship down to the ground” most certainly did not survive, including Captain Ernst Lehmann, who stumbled away from the control car after it touched ground, Engineer Wilhelm Dimmler, who was trapped in the electrical room, steward Max Schulze, who was caught in the bar, stewardess Emilie Imhoff, who was on B-Deck, 14-year old passenger Irene Doehner, who was in the dining room when the ship settled to the ground and died of her burns, and dozens of others.]

Silverwood Energy makes the same recycled claim, including the reference to “clean hydrogen flames.”

The American Hydrogen Association newsletter states “The sixty-two surviving persons that rode the gently falling Hindenburg (emphasis added) to the ground had only slight injuries” [Hydrogen Today, vol. 10, no. 2, 1999, p.9 – download pdf]. And another website similarly claims that “those who remained aboard the ship during its relatively gentle descent to the ground escaped with minor injuries.”

[The concept of a “gently falling Hindenburg” is certainly not borne out by films of the disaster, which show the airship crashing violently to the ground in less than half a minute.]

One hydrogen cell retailer offers a “Brief History of Hydrogen” in which they discuss the Hindenburg and state: “the hydrogen burned safely above the passengers and didn’t cause a single death.”

And there is a hydrogen advocate who argues that “Hydrogen was used very successfully as a lifting gas until the Hindenburg disaster gave it an unwarranted bad reputation.”

[Dozens of hydrogen-inflated airships had exploded or burned prior to the Hindenburg disaster.]

This same hydrogen advocate claims “it is even possible that the hydrogen contained within the Hindenburg when the skin caught fire actually mitigated the disaster somewhat if anything.”

The Truth

How does one even begin to address the claim that over 5 million cubic feet of hydrogen can burn in about 34 seconds, and completely destroy an 800-foot airship, and yet not injure any of the passengers or crew?

Would a fire of the covering alone have caused sufficient heat for the duralumin framework to melt and collapse on the passengers an crew?

Burning hydrogen caused the duralumin framework to collapse on passengers and crew still trapped within the wreckage.

  • One could review the scientific evidence (above) demonstrating that the covering alone would have taken up to 40 hours to burn, so if the Hindenburg had been inflated with helium, the passengers and crew would have had ample time to exit to safety.
  • One could list the fatalities of the Hindenburg disaster and describe how each one died.

Hindenburg historian Patrick Russell has a brilliant blog which describes the fate of each person on Hindenburg’s final flight. Patrick’s research conclusively refutes the oft-cited claim that “35 of the 37 casualties perished from jumping to the ground” rather than from the fire itself, although even if that claim were true these victims would not have needed to jump from a burning airship in the first place if the Hindenburg had been inflated with helium rather than hydrogen.

Location of 9 crew members killed in the bow

Location of 9 crew members killed in the bow (click to enlarge)

  • One could refer to a diagram [click to view] showing the locations of the crew (survivors in green, casualties in red). Crew members and passengers who were in a position to exit quickly generally lived, while those who were trapped in the ship as it settled to the ground died in the fire.
  • One could point to the respected scientists and airship experts (both at the time of the crash, and today) who agree that the presence of hydrogen which was responsible for the severity of the catastrophe.
  • One could consider the lack of fire in the many incidents and accidents involving helium-inflated airships, including the crash of the USS Shenandoah and the USS Akron (which were both, by the way, doped with an aluminum powder solution).
  • Or one could simply watch the film of the disaster once again, watch the hydrogen furiously burning and consuming the ship in a matter of seconds, and approach the matter with basic common sense.

But perhaps the larger point is the absurdity of this debate itself. In their determination to exonerate hydrogen at all costs, hydrogen advocates like Greg Blencoe and others have made the macabre, autopsy-like argument that it was not the hydrogen itself which killed the victims of the Hindenburg, but other things (diesel fuel, burning material from the cabins, jumping from a great height… anything but hydrogen). But even if those arguments were true — which they are simply not — do the hydrogen advocates really think it matters what particular substance (hydrogen, diesel fuel, or burning bed linens) caused particular injuries, since the Hindenburg itself would not have crashed to the ground in less than a minute if had not been inflated with hydrogen?

These arguments are like claiming that the San Francisco earthquake of 1906 did not cause many casualties, since most of the deaths were actually caused by the ensuing fire, and not by the earthquake itself.

The Irony of the Hydrogen Advocates

Many of the myths about the Hindenburg disaster — from the nonsense about rocket fuel to the absurd claim that nobody was injured by the hydrogen fire — have been circulated and promoted by hydrogen advocates who seem determined to prove that anything but hydrogen was responsible for the destruction of the Hindenburg and the deaths of its victims.

twitter-rocket-fuel

Twitter stream of the South Carolina Hydrogen and Fuel Cell Alliance (click to enlarge)

For example, the South Carolina Hydrogen and Fuel Cell Alliance (whose board of directors seems to include people with a scientific background) uses its Twitter account to send frequent and repetitive tweets claiming that “NASA” found that the Hindenburg’s covering was “sealed w/ solid rocket fuel.”

The National Hydrogen Association website publishes an FAQ and distributes a “Fact Sheet” [pdf] which make a similar claim.

And in their zeal to exonerate hydrogen, the hydrogen advocates are not restrained by the normal rules of logic. For example, to support its claim that no-one was harmed by the hydrogen fire on the Hindenburg, the American Hydrogen Association states that the hydrogen fire “was over in less than a minute.”

They explain:

“In less than one minute after the hydrogen bags were interrupted and the hydrogen started to escape, the hydrogen was gone. You can count the seconds in the news reel film of the disaster.” [Hydrogen Today, vol. 10, no. 2, 1999, pp. 8,9 – download pdf]

They are correct. The hydrogen was gone in less than a minute… because the entire airship was gone in less than a minute.

How do the hydrogen advocates expect to be taken seriously on other matters relating to science and technology, when they are willing to put their names, websites, and reputations behind unscientific urban myths and absurdly illogical arguments?

The great irony is that the nonsensical claims about the Hindenburg disaster offered by these hydrogen advocates, which so badly undermine their own seriousness and credibility, are completely unnecessary to their cause. The fact that hydrogen was responsible for the Hindenburg disaster is completely irrelevant to whether or not hydrogen makes a good alternative to fossil fuels. In fact, hydrogen could (theoretically) be both a wonderful alternative fuel and a terrible lifting gas for passenger airships; there is no necessary contradiction between the two. Many substances which are ideal for one application are hazardous in another, and hydrogen advocates like those mentioned above, who can’t seem to understand or express this simple concept, just raise questions about their own analytical abilities. Many people support solar energy, but they don’t feel the need to claim that sunlight never causes skin cancer.

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