My Overview on Hindenburg Incident

The Zeppelin that flew from Europe across the Atlantic Ocean was known as the Titanic of the air. As the huge Zeppelin approached Lakehurst, New Jersey, the large aircraft burst into flame and went down in a burning heap of fire. The burning Zeppelin fell from the sky. It only killed 35 people, but injured many more.

There are some hypotheses that can be considered:

1.1        Sabotage Hypothesis:

1.1.1  Hugo Eckener; At the time of the disaster, sabotage was commonly put forward as the cause of the fire, initially by Hugo Eckener, former head of the Zeppelin Company and the "old man" of German airships. Eckener later publicly endorsed the static spark hypothesis.

1.1.2  Capt. Max Pruss; Another proponent of the sabotage hypothesis was Max Pruss, commander of the Hindenburg throughout the airship's career. Pruss flew on nearly every flight of the Graf Zeppelin until the Hindenburg was ready. In a 1960 interview conducted by Kenneth Leish for Columbia University's Oral History Research Office, Pruss said early dirigible travel was safe, and therefore he strongly believed that sabotage was to blame. He stated that on trips to South America, which was a popular destination for German tourists, both airships passed through thunderstorms and were struck by lightning but remained unharmed.

1.1.3  Passenger Destroy the airship as the airship’s crew statement.

1.1.4  Eric Spehl; In 1962, A. A. Hoehling published Who Destroyed the Hindenburg?, where he rejected all theories but sabotage, and named a crew member as the suspect. Eric Spehl, a rigger on the Hindenburg who died in the fire. Ten years later, Michael MacDonald Mooney's book, The Hindenburg, which was based heavily on Hoehling's sabotage hypothesis, also identified Spehl as the saboteur; Spehl involvement: (i) Spehl’s girl friend was a communist; (ii) Spehl is located near the fire source; (iii) Gestapo investigations of Spehl involvement in 1938; (iv) Spehl took foto as igniter; (v) NYPD and FBI Finding on initial fire location in regards to Bomb teat and Spehl unable to reset.

1.1.5  Adolf Hitler: It has even been suggested that Adolf Hitler himself ordered the Hindenburg to be destroyed in retaliation for Eckener's anti-Nazi opinions. Neither the German nor the American investigation endorsed any of the sabotage theories.

1.2        Static Spark Hypothesis:

1.2.1  Hugo Ackner; this is not electric spark but caused by Static Spark. The spark ignited hydrogen on the outer skin. The airship's skin was not constructed in a way that allowed its charge to be distributed evenly throughout the craft. The skin was separated from the duralumin frame by non-conductive ramie cords which had been lightly covered in metal to improve conductivity, but not very effectively, allowing a large difference in potential to form between them.

1.2.2  The Hindenburg passed through a weather front of high humidity and high electrical charge. When the ropes, which were connected to the frame, became wet, they would have grounded the frame but not the skin. This would have caused a sudden potential difference between skin and frame (and the airship itself with the overlying air masses) and would have set off an electrical discharge – a spark. Seeking the quickest way to the ground, the spark would have jumped from the skin onto the metal framework, igniting the leaking hydrogen.

1.2.3  In his 1964 book, LZ-129 Hindenburg, Zeppelin historian Dr. Douglas Robinson points out that although ignition of free hydrogen by static discharge had become a favored hypothesis, no such discharge was seen by any of the witnesses who testified at the official investigation into the accident back in 1937.

1.2.4  Addison Bain; that a spark between inadequately grounded fabric cover segments of the Hindenburg itself started the fire, and that the spark had ignited the "highly flammable" outer skin. The Hindenburg had a cotton skin covered with a finish known as "dope". It is a common term for a plasticized lacquer that provides stiffness, protection, and a lightweight, airtight seal to woven fabrics. In its liquid forms, dope is highly flammable, but the flammability of dry dope depends upon its base constituents, with, for example, butyrate dope being far less flammable than cellulose nitrate. Proponents of this hypothesis claim that when the mooring line touched the ground, a resulting spark could have ignited the dope in the skin

1.3        Lightning Hypothesis:

1.3.1  A. J. Dessler, former director of the Space Science Laboratory at NASA's Marshall Space Flight Center and a critic of the incendiary paint hypothesis (see below), favors a much simpler explanation for the conflagration: lightning. Like many other aircraft, the Hindenburg had been struck by lightning several times. This does not normally ignite a fire in hydrogen-filled airships, because the hydrogen is not mixed with oxygen. However, many fires started when lightning struck airships as they were venting hydrogen as ballast in preparation for landing, which the Hindenburg was doing at the time of the disaster. The vented hydrogen mixes with the air, making it readily combustible.

1.4        Engine Failure Hypothesis

1.4.1  Philadelphia Inquirer:  Based on the interview with Robert Buchanan, a crew manning mooring line. As the airship was approaching the mooring mast, he noted that one of the engines, thrown into reverse for a hard turn, backfired, and a shower of sparks was emitted. After being interviewed by Addison Bain, Buchanan believed that the airship's outer skin was ignited by engine sparks. Another ground crewman, Robert Shaw, saw a blue ring behind the tail fin and had also seen sparks coming out of the engine. Shaw believed that the blue ring he saw was leaking hydrogen which was ignited by the engine sparks.

1.5        Incendiary Paint Hypothesis

1.5.1  Paddison Bain: stating that the doping compound of the airship was the cause of the fire. The hypothesis is limited to the source of ignition and to the flame front propagation, not to the source of most of the burning material, as once the fire started and spread the hydrogen clearly must have burned.

1.5.2  Proponents of this hypothesis point out that the coatings on the fabric contained both iron oxide and aluminum-impregnated cellulose acetate butyrate (CAB).These components remain potentially reactive even after fully setting. In fact, iron oxide and aluminum can be used as components of solid rocket fuel or thermite. For example, the propellant for the Space Shuttle solid rocket booster includes both "aluminum (fuel, 16%), (and) iron oxide (a catalyst, 0.4%)".

1.6        Hydrogen Hypothesis

1.6.1  Offering support for the hypothesis that there was some sort of hydrogen leak prior to the fire is that the airship remained stern-heavy before landing. There are many theories about how that gas might have leaked, but the actual cause remains unknown. Many believe it was that a bracing wire cracked (see below), while others believe that a vent was stuck open and gas leaked through. During one trip to Rio, a gas cell was nearly emptied when a vent was stuck open, and gas had to be transferred from other cells to maintain an even keel.

1.7        Puncture Hypothesis

1.7.1  One hypothesis on how gas could have leaked is that one of the many bracing wires within the airship snapped and punctured at least one of the internal gas cells during one of the sharp turns in the landing maneuver.

1.7.2  Advocates of this hypothesis believe that the hydrogen began to leak approximately five minutes before the fire. Newsreels as well as the account of the landing approach show the Hindenburg made several sharp turns, first towards port and then starboard, just before the accident. Gauges found in the wreckage showed the tension of the wires was much too high, and some of the bracing wires may have even been substandard. One bracing wire tested after the crash broke at a mere 70% of its rated load. A punctured cell would have freed hydrogen into the air and could have been ignited by a static discharge (see above), or it is also possible that the broken bracing wire struck a girder causing sparks to ignite hydrogen

1.8        Structural Failure Hypothesis

1.8.1  Captain Pruss believed that the Hindenburg could withstand tight turns without significant damage. Other engineers and scientists believe that the airship would have been weakened by being repeatedly stressed. The airship's landing approach proceeded in two sharp turns. The first turn was towards port at full speed as the airship circled the landing field. After it had circled the landing field, the wind shifted direction towards the southwest, and a sharper turn to starboard was ordered near the end of the landing maneuver. One or both of these turns in opposite directions could have weakened the structure

1.9        Fuel Leak Hypothesis

1.9.1  The 2001 documentary Hindenburg Disaster: Probable Cause suggested that 16-year-old Bobby Rutan, who claimed that he had smelled "gasoline" when he was standing below the Hindenburg's aft port engine, had detected a diesel fuel leak. During the investigation, Commander Charles Rosendahl dismissed the boy's report. The day before the disaster, a fuel pump had broken during the flight. A crew member said this was fixed but it may not have been done properly. The resulting vapor would have been highly flammable and could have self combusted. The film also suggested that overheating engines may have played a role.

The most conclusive proof against the fabric hypothesis is in the photographs of the actual accident as well as the many airships which were not doped with aluminum powder and still exploded violently: Regardless of the source of ignition or the initial fuel for the fire, there remains the question of what caused the rapid spread of flames along the length of the airship. Here again the debate has centered on the fabric covering of the airship and the hydrogen used for buoyancy.

After the incident occurred, it was determined that the “new & improved” covering the exterior of the aircraft was very flammable. The slightest spark easily could have set the covering ablaze. Most people believed that the air inside the aircraft keeping it aloft was to blame, saying that it was too rich in oxygen; however, this is not the case. It is believed that as the Zeppelin approached Lakehurst, static friction caused a spark that sent the craft crashing to the ground! Since then, all new materials undergo rigorous property testing for strength and ignition point (the point when an object is able to light on fire).