"Hindenburg fire not caused by hydrogen" Topic

I watched a show on PBS, I believe, that presented a compelling case against the case of hydrogen as the cause of the fire that consumed the Hindenburg Zeppelin. (Mythbusters did a show on this too, albeit much less scientifically.)

Rather, the fire was caused by static electricity igniting the highly flammable outer fabric covering of the aircraft. The hydrogen gas was no doubt released and burned during the fire, but was not in itself the source of the initial ignition nor the rapid spreading of the fire.

In a nutshell, here is the case:

Electrical charge builds up on any structure passing through the air at high speed. The designers of lighter than air craft anticipate this and design the frame so that it is electrically bonded and any excess electrical charge will harmlessly conduct through the frame to the ground during landing. This was NOT the case for the fabric covering, however. Even though the fabric was doped with a mixture of aluminum and iron oxide (the principle ingredients of thermite, by the way), the covering was in discrete panels that were stitched together over the frame with non-conducting cord, leaving gaps between the panels. Rain that had fallen onto the aircraft would have wetted some, but not all, of the cords, making them more or less conductive. When the craft approached the ground and dropped the landing lines, the frame and much of the covering of the Hindenberg discharged to ground. Some of the covering panels, however, remained electrically isolated from the others. The difference in electrostatic potential caused a spark to jump the gap between the panels. This ignited the fabric covering, which then spread rapidly over the entire craft. You can see this happening in the film of the fire. Hydrogen burns nearly invisibly, and should generally be travelling upward. The fire that consumed the Hindeburg burns bright orange and downward, spread from near the back and top of the airship.

So, while hydrogen may not be the safest thing to fill your airship with, it was not the cause of the Hindenburg fire.

This would seem to be a repeat of a show we've had shown in the UK at least twice, that I've seen.

Very good documentary in my opinion, especially as it tended to concentrate on the facts rather than have lots of CGI and 'reconstructions' in it.

It was one of the "Secrets of the Dead" series.

link

Yup, saw that a while back and they made a good case. "Secrets of the Dead" is a good series overall.

Has electrostatics and the fabric been accepted as the cause for over a decade now? At least that is what I have heard for many years now!

Has electrostatics and the fabric been accepted as the cause for over a decade now? At least that is what I have heard for many years now!

That could be. This was the first time I personally had seen a solid, complete case presented so that the average man of the street (or in my case, on the sofa) could understand it.

All too often, the "popular" media tends to oversimply things because it assumes we could never understand it (or they themselves don't). Saying the Hindenburg fire was caused by static electricity is about as explanatory as saying the car accident was caused by impact with another car.

That the hydrogen didn't cause the fire and wasn't the primary fuel has been known by scientists and engineers for a long time. For one thing, a volume of hydrogen contained in a gas bag can't catch fire— there's no oxygen present, and without oxygen you can't have a fire. The bag has to be ruptured first to allow the hydrogen to contact oxygen; even then an ignition source must be present to start the reaction— hydrogen and oxygen don't react with each other at low temperatures anymore than paper and oxygen do. Secondly, even if an ignition source is present, only the hydrogen in contact with oxygen will burn at the start; the majority of the hydrogen won't be intermixed with oxygen to begin with, and therefore won't burn. So the hydrogen would only ignite as it expanded through the rupture of the bag and came in contact with both flame and oxygen, which would produce only a relatively small flame at the point of exit, like you get with a blowtorch. In any case, as the hydrogen is much less dense than the surrounding air, the escaping hydrogen would quickly rise up and away from the dirigible's structure, not hang around and burn near the ground.

Remember your junior high physics experiment where you used electricity to split water into two test tubes, one containing hydrogen and one containing oxygen? Remember how you closed out the experiment— by inserting a flaming splint into each tube? In the oxygen tube, the splint immediately flamed brighter and burned up. In the hydrogen tube, the splint snuffed out. Absent oxygen, hydrogen doesn't burn. Q.E.D.

The reason the general public believes that the hydrogen-filled gas bags were the cause of the Hindenburg disaster is because, surprise, ignorant journalists told them so.

Sadly, not much has changed.

To paraphrase Woody Allen:

Those that can, do.

Those that can't, teach.

Those that can't teach, teach gym.

Those that can't teach gym, become journalists.

The one thing the Mythbusters did show was that you can get a flame from Hydrogen that looks just like what the film reels show. But then again we all know the hydrogen was the main source of the flames once the fire started.

Yes – I've seen this a couple of times in the UK as well. Seems they didn't know quite how well aluminium will burn given the right circumstances.

<quote>Has electrostatics and the fabric been accepted as the cause for over a decade now? At least that is what I have heard for many years now!<quote>

I'm pretty sure I heard that German documents from the 1930s had this as the accepted cause. They were just hidden away until recently.

Ok, you guys are confusing me. Engineers do not use hydrogen today because its dangers not because they read an article written by a journalist.

Yes, the hydrogen was not the first thing to catch fire. The cloth painted with an aluminum compound was the first to catch fire. But, as you can see on Myth Busters, the cloth alone--with various compound mixtures ranging from most likely to ridiculous--doesn't burn fast enough as compared to what's seen on film. When the burning cloth creates a big enough hole, the hydrogen catches on fire. The burning hydrogen, again as demonstrated on Myth Busters, does burn as fast as seen on film.

So, as a journalist, what answer you are going to give in your article. What's the cause of the fire or what's the cause of the disaster? The original fire was caused by the paint and static electricity. But this fire combined with helium would have caused the blimp to come down at a reasonable pace. But this fire was combined with hydrogen, went up like a fireball, and killed a bunch of people. So, you can say the use of hydrogen instead of helium caused the disaster.

Now add the fact that hydrogen was chosen due to political and economic forces while the cloth was treated with the best known method of the time. Therefore, people died because the maker chose to use cheap hydrogen vs. expensive helium. Granted, the fire could have been completely prevented if the Germans used their time machine and gone into the future and found out a better way to coat the cloth--but that seems unlikely. So I don't fault the journalists of the time for their explanation as to the cause of the Hindenburg disaster.

Hydrogen was chosen because the only source for helium in that time period was the United States, and they wouldn't sell helium to the Germans. The Hindenburg was, in fact, designed to use helium. It had extra gas cells since helium has less lifting power than hydrogen does.

Steve

I remember seeing that documentary, and I recall they conducted an experiment with an actual piece of the Hindenburg's fabric covering that was recovered at the crash site. Very interesting show.

That the dope used by Luftschiffbau Zeppelin was highly inflammable (and burned hot enough to ignite aluminum) was discovered during WWI. The fact wasn't "hidden away", it was just not widely publicized. Kind of like the supposedly "coverd up" Dresden firebombing raid that Kurt Vonnegut "exposed" in 'Slaughterhouse Five'.

Engineers do not use hydrogen today because its dangers not because they read an article written by a journalist.

The real reason they don't use hydrogen is because it's harder to contain than helium and leaks away more readily. The extra lift (36 v. 34 grams per mole, IIRC) isn't worth the extra handling problems. In fact, the extra structral weight needed is often greater than the lift difference.

rmaker, you masses are quite a bit off – the difference is much more dramatic!

1 mol of Hydrogen gas (H2 molecules) will have a mass (not weight) of 2 grams (assuming that most of the Hydrogen is the common isotope Hydrogen-1, not the heavier – and rarer – Deuterium [Hydrogen-2] or Tritium [Hydrogen-3] isotopes). 1 mol of anything weighs one gram per nucleon (proton or neutron) in each molecule. In this case, each molecule has two atoms, each of which has one proton and no neutrons.

1 mol of Helium gas (He molecules) will have a mass (not weight) of 4 grams (assuming that only the – overwhelmingly more common – isotope Helium-4 is present).

So, you can maintain atmospheric pressure on the inside of a balloon with only half the mass of Hydrogen, compared to what you would need to use if you used Helium.

Ah, I see you were talking about the lift generated by the difference between the mass of air and the mass of Hydrogen or Helium. Apologies for assuming you needed correcting – you are in fact quite right.

No problem. I put that in because way too many people look at the atomic weights and jump to the conclusion that a hydrogen aerostat will lift twice as much as a helium one of the same volume.