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Hindenburg disaster


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Jason Vorhees
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« Reply #90 on: November 23, 2009, 03:14:58 pm »

There also would have had to be a very large leak of hydrogen before stern heaviness could be observed, although given the end result this seems obvious. The stern heaviness was also noticed minutes before the airship made its sharp turns for its approach, and crew members stated that it was corrected as the ship stopped (after dropping over 1000 kg of water ballast and venting gas). Additionally, the gas cells of the ship were not pressurized, and when leaking would not cause the fluttering of the outer cover, which wasn't seen until seconds before the fire. Instead, it has been suggested that such fluttering was caused by the initial blast wave of the hydrogen cells igniting.
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Jason Vorhees
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« Reply #91 on: November 23, 2009, 03:15:08 pm »

While not issuing an opinion about whether it was the hydrogen or the treated skin of the airship that ignited first, the MythBusters explored the incendiary paint theory. Their findings indicated that the aluminum/iron oxide ratios in the Hindenburg's skin, while certainly flammable, were not enough on their own to destroy the zeppelin. Had the skin in fact contained enough metal to produce pure thermite, the Hindenburg would have been too heavy to fly. And even if it somehow did, a pure thermite reaction (at ~2500 degrees C) would have completely melted the airframe (assuming Aluminium 2024's melt point of ~630 degrees C for the duralumin of the day), whereas the real disaster left the spars and ribs recognizable. The MythBusters team also discovered that the Hindenburg's coated skin required a higher temperature to ignite than untreated material, but that after it was ignited the treated cloth reacted more violently. This led to their hypothesis that the paint may have contributed to the disaster, but that it was the hydrogen that ultimately caused the zeppelin to burn.[30]
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Jason Vorhees
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« Reply #92 on: November 23, 2009, 03:15:23 pm »

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Jason Vorhees
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« Reply #93 on: November 23, 2009, 03:15:43 pm »

Puncture theory

An aspect of the hydrogen theory above claims that one of the many bracing wires within the airship snapped and punctured at least one of the internal gas cells. Advocates of this theory believe that the hydrogen began to leak approximately five minutes before the fire.[18] 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, though possibly damaged by the fire, broke at a mere 70% of its rated load.[17] 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.[17].
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Jason Vorhees
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« Reply #94 on: November 23, 2009, 03:26:09 pm »

A ground crew member, R.H. Ward, reported seeing a piece of the airship fluttering, perhaps providing an opening for a spark to reach escaping hydrogen inside the airship, or vice versa. He said that the fire began there, but that no other disturbance occurred at the time when the fabric fluttered.[18] Another man on the top of the mooring mast had also reported seeing a flutter in the fabric as well.[31] People on board the airship reported hearing a muffled sound, and another ground crew member on the starboard side reported hearing a crack. Some speculate the sound was from a bracing wire snapping.[17]
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« Reply #95 on: November 23, 2009, 03:26:40 pm »

Dr. Eckener concluded that the puncture theory was the most likely cause of the disaster. Because of this, he felt that Captains Pruss and Lehmann, and Charles Rosendahl were to blame for the whole disaster.[18] He believed that Lehmann told Pruss to make the sharp turn, and that Pruss and Rosendahl were concerned more about the time delay than the weather, because an unobserved storm front occurred just when the Hindenburg approached.[18] But in his heart, Dr. Eckener knew that he was to blame as much as anyone else, for a decision eight years earlier, which he kept a close secret.[18][32]

Eckener concluded that the fire was caused by the ignition of hydrogen by a static spark:
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Jason Vorhees
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« Reply #96 on: November 23, 2009, 03:27:23 pm »

I believe that the fire was not caused by an electrical spark, but by a static spark. A thunderstorm front had passed before the landing maneuver. However if one observes more closely one can see that this was followed by a smaller storm front. This created conditions suitable for static sparks to occur. I believe spark had ignited gas in the rear of the ship.

It may seem strange that the fire did not occur the moment the landing ropes had touched the ground, because that is when the airship would have been earthed. I believe there is an explanation for this. When the ropes were first dropped they were very dry, and poor conductors. Slowly however they got dampened by the rain that was falling and the charge was slowly equalized. Thus the potential difference between the airship and the overlying air masses would have been sufficient enough to generate static electricity. The Hindenburg would have acted as a giant kite, close to the storm clouds, collecting a static spark.
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« Reply #97 on: November 23, 2009, 03:27:37 pm »

I am convinced, that a leak must have occurred in the upper rear section of the ship. My assumption is confirmed by the remarkable observations by one of the witnesses. He described seeing a peculiar flutter as if gas were rising and escaping. If I were to be asked to explain what had caused this abnormal build up of gas, I could only make to myself one explanation.

The ship proceeded in a sharp turn during its landing maneuver. This would have generated extremely high tension in the sections close to the stabilizing fins, which are braced by shear wires. I suspect that under such tension one of these wires may have broken and caused a rip in one of the gas cells. The gas then filled up the space between the cell and the outer cover, which is why the airship sank at the rear. This accumulated amount of gas was then ignited by a static spark. This was not lightning but a small static spark, enough to ignite free gas in the rear.[18]
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« Reply #98 on: November 23, 2009, 03:27:58 pm »

Other controversial hypotheses

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. Even a 10-meter, scale replica of the Hindenburg's passenger quarters, displayed in the Zeppelin Museum in Friedrichshafen, has developed some metal fatigue.

The airship's landing approach actually 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. After the last turn the airship seemed to drop even more at the stern, though a slight stern heaviness had already been noticed before this turn. One or both of these turns in opposite directions could have weakened the structure.
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« Reply #99 on: November 23, 2009, 03:28:11 pm »

However, evidence against this theory is the fact that the first sharp turn was too wide and circular to cause any damage, and that the final turn, while considered sharp, was far too slow for any structural failure to occur.

The airship did not receive much in the way of routine inspections even though there was evidence of at least some damage on previous flights. It is not known whether that damage was properly repaired or even whether all the failures had been found. The Hindenburg had once lost an engine and almost drifted over Africa, where it could have crashed. Dr. Eckener was furious and ordered all section chiefs to inspect the airship during flight.
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« Reply #100 on: November 23, 2009, 03:28:30 pm »

In March 1936, the Graf Zeppelin and the Hindenburg made three-day flights to drop leaflets and broadcast speeches via loudspeaker. Before the airship's takeoff on 26 March 1936, Captain Lehmann chose to launch the Hindenburg with the wind blowing from behind the airship, instead of into the wind as per standard procedure. During the takeoff, the airship's tail struck the ground, and part of the lower fin was broken.[33] Many spectators' cameras were confiscated to prevent negative publicity, but Harold G. Dick concealed his camera and took pictures of the damaged fin. Dr. Eckener was very upset and rebuked Captain Lehmann:

    How could you, Herr Lehmann, order the ship to be brought out in such wind conditions. You had the best excuse in the world for postponing this idiotic flight; instead, you risk the ship, merely to avoid annoying Herr Goebbels. Do you call this showing a sense of responsibility towards our enterprise?[15]
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« Reply #101 on: November 23, 2009, 03:28:39 pm »

Though that damage was repaired, the force of the crash may have caused internal damage.

Only six days before the disaster, there was a plan assisted by the U.S. Navy to make the Hindenburg have a hook on her hull to carry aircraft in a similar way to what the Navy did with the USS Akron and the USS Macon. However, the trials were unsuccessful; the biplane had bashed the hook several times. This could have also caused damage and weakening of the structure.
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« Reply #102 on: November 23, 2009, 03:28:50 pm »

Photographs and newsreels of the initial stages of the fire show that the stern section of the airship collapsed inward in a similar way to an eggshell, as well as a "crack" directly behind the passenger decks. When the stern of the ship hit the ground and collapsed, this part collapsed inward, causing another plume of fire to start. Some experts[who?] have suggested that the collapsing of the structure in this manner suggests problems within the cell bulkheads and the bracing wires.

This theory has not been very popular because it is not so much about what caused the fire as an element of support for the puncture theory.
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« Reply #103 on: November 23, 2009, 03:29:04 pm »

Fuel leak

The 2001 documentary Hindenburg Disaster: Probable Cause suggested that 16-year-old Bobby Rutan, who said he had smelled "gasoline" when he was standing below the Hindenburg's aft port engine, had detected a diesel fuel leak. 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.

During the investigation, Commander Charles Rosendahl dismissed the boy's report.

Critics say the documentary is misleading, because it misconstrued the statements by the crewmen in the Hindenburg's lower fin. The crewmen said they saw a flash in the axial catwalk, but the film placed the flash in the keel catwalk closer to the passenger areas.
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« Reply #104 on: November 23, 2009, 03:29:39 pm »

Luger pistol among wreckage

Some more sensational newspapers at the time said that a person on board committed suicide because a Luger pistol with one shell fired was found among the wreckage.[15][34] Yet, there is no such evidence suggesting an attempted suicide. One thing to consider was that the Luger pistol ejected each empty round after firing, and that some owners would keep an empty shell in the gun for safety reasons.
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