Hindenburg disaster

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On May 6, 1937, at 19:25 the German zeppelin Hindenburg caught fire and was utterly destroyed within a minute while attempting to dock with its mooring mast at Lakehurst Naval Air Station in New Jersey. Although the disaster is famous, of the 97 people on board, only 35 died.

The LZ-129 Hindenburg was the largest aircraft ever built. The craft was named after the President of Germany, Paul von Hindenburg. It was a brand-new all aluminium design: 245 m long (804 feet), 41 m in diameter (135 ft), containing 211,890 m³ of gas in 16 bags or cells, with a useful lift of 112 tons, powered by four 1100 horsepower (820 kW) engines giving it a maximum speed of 135 km/h (83 mph). It could carry 72 passengers (50 transatlantic) and had a crew of 61. For aerodynamic reasons the passenger quarters were contained within the body rather than in gondolas. It was skinned in cotton, doped with iron oxide and cellulose acetate butyrate impregnated with aluminium powder. Constructed by Luftschiffbau Zeppelin in 1935 at a cost of £500,000, it made its first flight in March 1936 and completed a record double-crossing in five days, 19 hours, 51 minutes in July.

The Hindenburg was intended to be filled with helium but a United States military embargo on helium forced the Germans to use highly flammable hydrogen as the lift gas. Knowing of the risks with the hydrogen gas, the engineers used various safety measures to keep the hydrogen from causing any fire when it leaked, and they also treated the airship's coating to prevent electric sparks that could cause fires.

The disaster is remembered because of extraordinary newsreel coverage, photographs, and Herbert Morrison's recorded radio eyewitness report from the landing field. Morrison's words were not broadcast until the next day. Parts of his report were later dubbed onto the newsreel footage (giving an incorrect impression to some modern eyes accustomed to live television that the words and film had always been together). See: Hindenburg Disaster Newsreel Footage.

There had been a series of other airship accidents (none of them Zeppelins) prior to the Hindenburg fire, most due to bad weather. However, Zeppelins had accumulated an impressive safety record. For instance, the Graf Zeppelin had flown safely for more than 1 million miles (1.6 million km) including making the first complete circumnavigation of the globe. The Zeppelin company was very proud of the fact that no passenger had ever been injured on one of their airships.

But the Hindenburg accident changed all that. Public faith in airships was completely shattered by the spectacular movie footage and live voice recording from the scene. Because of this vivid publicity, Zeppelin transport came to an end. It marked the end of the giant, passenger-carrying rigid airships.

Questions and controversy surround the accident to this day. There are two major points of contention: 1) How the fire started and 2) Why the fire spread so quickly.

At the time, sabotage was commonly put forward as the cause of the fire, in particular by Hugo Eckener, former head of the Zeppelin company and the "old man" of the German airships. The Zeppelin airships were widely seen as symbols of German and Nazi power. As such, they would have made tempting targets for opponents of the Nazis. However, no firm evidence supporting this theory was produced at the formal hearings on the matter.

Although the evidence is by no means conclusive, a reasonably strong case can be made for an alternative theory that the fire was started by a spark caused by static buildup. Proponents of the "static spark" theory point to the following:

The airship's skin was not constructed in a way that allowed its charge to be evenly distributed and the skin was separated from the aluminum frame by nonconductive ramie cords. The ship passed through a moist weather front. The mooring lines were wet and therefore conductive. As the ship moved through the moist air the skin became charged. When the wet mooring lines connected to the aluminum frame touched the ground they grounded the aluminum frame. The grounding of the frame caused an electrical discharge to jump from the skin to the grounded frame. Witnesses reported seeing a glow consistent with a St. Elmo's fire.

The controversy around the rapid spread of the flames centres around whether blame lies primarily with the use of hydrogen gas for lift or the flammable coating used on the outside of the envelope fabric.

Proponents of the "flammable fabric" theory contend that the extremely flammable iron oxide and aluminum impregnated cellulose acetate butyrate coating could have caught fire from atmospheric static, resulting in a leak through which inflammable hydrogen gas could escape. After the disaster the Zepplin company's engineers determined this skin material, used only on the Hindenburg, was more flammable than the skin used on previous craft. Cellulose acetate butyrate is of course inflammable but iron oxide increases the flammability of aluminum powder. In fact iron oxide and aluminum can be used as components of solid rocket fuel.

Hydrogen burns invisibly (emitting light in the UV range) so the visible flames (see photo) of the fire could not have been caused by the hydrogen gas. Also motion picture films show downward burning. Hydrogen, being less dense than air, burns upward. Some speculate that the German government placed the blame on inflammable hydrogen in order to cast the U.S. helium embargo in a bad light.

Also, the naturally odorless hydrogen gas in the Hindenburg was 'odorised' with garlic so that any leaks could be detected, and nobody reported any smell of garlic during the flight or at the landing prior to the disaster.

Opponents of the "flammable fabric" theory contend that it is a recently developed analysis focused primarily on deflecting public concern about the safety of hydrogen. These opponents contend that the "flammable fabric" theory fails to account for many important facts of the case.

A film entitled The Hindenburg, directed by Robert Wise, was released in 1975. A highly speculative thriller, it portrays a conspiracy leading to the destruction of the airship.