David Brown (dbrown@ea.ucla.edu)

 

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May 28, 1998

 

Hydrogen Didnít Cause Hindenburg Fire, UCLA Engineer, Former NASA Researcher Find

It was not hydrogen that caused the disastrous fire aboard the famous Hindenburg zeppelin, according to a UCLA School of Engineering and Applied Science Professor and a former NASA researcher.

Hindenburg

Contrary to popular belief ó and the findings of two official investigations ó the material used to coat the "skin" of the airship, not hydrogen, was the cause of the disaster, said William D. Van Vorst, professor emeritus of chemical engineering at UCLA and Addison Bain, former manager, Hydrogen Programs Kennedy Space Center, NASA.

Their findings are revealed in a paper titled "Hydrogen and the Hindenburg," to be presented at a symposium in Antalya, Turkey, June 18-20.

A stately and luxuriously appointed airship some 804 feet long, this "Titanic of the skies" was destroyed by a flash fire in 1937 while landing in New Jersey after making its 10th transatlantic crossing. Thirty-five of the 97 people aboard and one ground crew member were killed when the zeppelin burst into flames and was rapidly consumed by the fire.

Two boards of inquiry seeking an explanation for the disaster concluded, "Some hydrogen had, in a manner never explained, become free, was ignited electrostatically and exploded," Van Vorst said. And for more than 60 years, the word "hydrogen" has evoked the newsreel images of the huge craft being consumed by a fireball as it drifted to the ground.

By studying that newsreel footage, examining the chemical composition of the skin and delving into the records of the German firm which built the Hindenburg, however, they pulled together three independent pieces of compelling evidence indicating hydrogen could not have been the culprit.

Newsreel footage contradicts the hydrogen theory, said Van Vorst, who studied individual frames of the footage. "The picture indicates a downward burning. Hydrogen would burn only upward!"

In addition, Van Vorst pointed out, "hydrogen burns with a colorless flame," yet witnesses compared flames aboard the Hindenburg "with a fireworks display." There is also a remarkable similarity between what can be seen in the newsreel footage of the Hindenburg and the photos and witness descriptions of fires aboard airships containing no hydrogen, but covered with similar materials, Van Vorst said.

Furthermore, the substance used to coat the cotton skin ó a process known as "doping" which makes the fabric taut and more durable ó was extremely flammable. A combination of iron oxide, cellulose acetate and aluminum powder, "the total mixture might well serve as a respectable rocket propellant," Van Vorst said.

Additionally, the manner in which the skin was attached to the airframe allowed a large electrostatic charge to build up on its surface. When it finally discharged, it did so with disastrous results.

"As a result of the electrostatic activity, the skin became highly charged, and finally passed the current through the skin to the frame. In the process, the skin and its highly energetic doping constituents were ignited, setting off the conflagration," Van Vorst said in the paper.

Analysis of the sister airship, the Graf Zeppelin, being constructed at the time of the Hindenburg accident, indicates remedial measures were quickly undertaken, he said. Calcium sulfumate, a chemical widely used in the textile industry as a fireproofing agent, was added to the doping mixture. The doping compound was further modified by substituting bronze for aluminum. Though heavier, the bronze was far less combustible. Furthermore, the bronze was highly conductive, allowing any static charges to be bled off, rather than build up. Also, the cord holding the fabric in place was impregnated with graphite to make it conductive, thus reducing the electrical potential between skin and structure.

"Clearly, there must have been strong suspicion that the fabric was the real culprit," Van Vorst said. With these changes in place, the Graf Zeppelin, which was also kept aloft by hydrogen, went on to fly more than a million miles without incident.

Furthermore, according to a letter from electrical engineer Otto Beyersdorff, hired by the Zeppelin Company as an independent investigator: "The actual cause of the fire was the extremely easy flammability of the covering material brought about by the discharges of an electrostatic nature." Beyersdorff went on to say he had tested samples of the material in the laboratory "matching the conditions of the accident, which proved the material to be easy to inflame."

 Even though letters from an independent investigator and the decision to make design changes in the Graf Zeppelin indicate the company knew the true cause of the blaze, Hugo Eckener, chairman of the Zeppelin Company publicly blamed hydrogen for disaster. Van Vorst speculated this might have been done to show the United States in an unfavorable light for being unwilling to supply helium for use as the buoyant force. He also suggests it might have been an effort to cover up what proved to be poor design decisions in the choice of doping materials.

 Van Vorst, who has spent much of his academic career exploring the use of hydrogen as an alternative fuel, sees the findings as further proof of his contention that hydrogen is a safe alternative to gasoline.

 "The public must be made aware that hydrogen may be used as a fuel with the same degree of safety as gasoline," he said.

 "With proper handling," Van Vorst said, "hydrogen is no more hazardous than gasoline and may, indeed, be less so.

 "Actually, its great buoyancy and extremely high diffusivity in air make for a very rapid dispersal before ignition can take place," Van Vorst further noted. "Gasoline, on the other hand, with its heavier-than-air vapor, simply accumulates until a flammable mixture is formed and ignites." In fact, he said, hydrogen is even "safer than propane, and is on a par with natural gas."

 Systems for using hydrogen as a fuel were developed for the space program during the 1960s and 1970s. Commercial development is now well under way and municipal buses powered by fuel cells are in operation in the United States, Canada and Germany. The byproduct of fuel cells is water and, unlike most other alternative fuels such as methyl alcohol, ethyl alcohol, natural gas, propane, butane and toluene, hydrogen does not contribute to the carbon dioxide "blanket" effect and the consequent warming of the earth, Van Vorst said.