That was just a guess though, entirely based on the fact that they observed sparks which they said was a thermite reaction. The only way to definitively prove it would have been to do a test with a plain cotton model.
What bothers me about the conclusion that the dope hastened the fire is that an experiment similar to the Mythbusters’ small-scale experiment was already done, with much different results:
Burn Tests of Cellulose Acetate Butyrate (Cellon) Doped Cotton Fabric:
Coats refer to cellulose acetate butyrate
Plain cotton fabric, no coating 29.4 seconds
Cotton with 4 coats, no additives 62.2 seconds
Four coats, top 3 coats contained
aluminum powder (replicating the lower
half of the Hindenburg) 55.7 seconds
Four coats, 1st coat with iron oxide, next
3 coats contained aluminum powder
(replicating the upper half of the
Hindenburg) 68.3 seconds
It took MUCH longer for the doped cotton to burn than cotton alone, which isn’t the result the Mythbusters got. So something was fishy about the small-scale test. I would have been nice to have some sort of comparison on the large-scale test.
I remember a documentary about the Hindenberg about 10 years ago advocating the fabric dope theory. On the show scientists tested a surviving fragment of the real hull fabric by putting it to a flame. The fabric went up like a roman candle. Also record from the Zeppelin company showed they were aware of a possible problem with the dope mixture they were using. So I don’t know what to believe, mythbusters claimed the dope they were using was exactly the same formula the Hindenberg used, but was it really?
Lowbrass, the PDF you linked to appears to agree with the Mythbuster’s findings. On my hasty read through they appear to have just painted peices of fabric and lit them on fire. The Mythbusters did the exact same test in the first ten minutes of the show with similar results. Then they wanted to check it in the presence of hydrogen so they went on to build models to test it. The authors of the paper seem to have just stopped with the fabric.
I can’t be sure, but since many of the problems with the paint theory raised in that paper were mentioned in the episode (“Critics of the dope theory say…”) I think it’s likely that they were aware of their experiment.
Setting a fifty year old piece of fabric on fire isn’t really something that I’d go to as proof. It is a good starting point but things change over time making it necessary to look at it with accurately reconstructed materials. Still, there are some variables that I didn’t see addressed in the show. What happens if they apply the second coat while the first one is still wet mixing the layers a bit better? Does it burn faster then?
Please cite to those experiments. That one has been always burning me (no pun intended). Just because they were too dumb to aim mirrors at first try doesn’t mean that trained soldiers couldn’t do it with practice (this is my basic complain to most their failures, actually).
Soldiers with single mirrors with an aiming guide (just as you use your fingers to aim he reflection when signaling an SOS) seems to me the way to go. The array is a total non-sense.
I rather doubt that the Mythbusters had the budget to hire 1,000 soldiers to stand around all day. Not even the MIT team (who actually set dry timber on fire using mirrors) did that. Again, the myth isn’t whether you can set things on fire using mirrors. The myth is whether Archimedes would have done so.
One issue I noticed on the small scale blimp tests is that when they lit the fabric intially, they started the timer. If you watch the footage of their tests, after about 30 seconds, the fire REALLY gets going. It seems to me that it needs to reach a critical level, then WHOOSH!!! goes the rest of the reaction. Since they were in 1/50 scale, it took a fair amount of the blimp being consumed to reach that level of heat. On the full size airship, a much smaller percentage would have been burning (and perhaps internally, and not visible in the historical footage) then WHOOSH!!! goes the Hindy.
If one was to start the timer at the beginning of the expanded burn, you’d end up with VERY similar times to the actual event.
I absolutely HATE, HATE, HATE that show.
They not only abuse science, they make a mockery out of it and present it as science.
They even go as far as blowing things up, saying that the explosive is C4 or dynamite or what have you and then you can clearly see that it is a standard fuel-bomb. (Big orange explosion with lots of black smoke).
Well, that’s the thing, Archimedes DID have the budget for not only the soldiers, but to train them and practice as much as needed. Actually, not a whole lot of training is needed. It turns out that aiming a reflection at a target is a very simple task if you know what you are doing.
It is Survival 101: If you need to signal a plane with a pocket mirror, stretch our arm and put your fingers in V with the plane in the middle of the fingers. With the mirror between your eyes and the fingers in V, make the reflection hit your fingers and that means it is hitting the plane.
I don’t know if Archimedes knew that or not but the fact that the mythbusters didn’t shows how little research went into it.
And the hull is the hardest target to ignite. Just go for the deck. Even if nothing catches fire, I can imagine that heat wreaking havoc among the crew. And something is bound to catch fire, ropes, sails, rags, whatever. Enough to get a fire going, specially with a confused crew.
I do not know if Archimedes did it or not, but I think he had all the tools needed. And I think that the fact that the mythbusters failed to do it at first try with limited motivation, time and budget is no proof that a genius with no limits on resources could not do it to save his life and with the advantage of surprise.
Regarding Archimedes’ mirror, if you just Google Archimedes Mirror Weapon you’ll get plenty of hits. There’s a Greek guy who posts things about ancient Greek Science who has a page on this, with some good references:
As he notes, Buffon in 1747 was able to ignite a plank at 150 feet using 168 8" X 10" mirrors.
In 1973 Ioannis Sakkas used a team of 60 sailors (a lot fewer than 1,000) holding mirrors to setr fire to a ship 160 feet away. I read about this in Time when it happened, and I’ve read interviews with Sakkas. Here’s a picture of that experiment:
I’ve read about another attempt, but I can’t find anything on it.
In any event, the French used to have a “Solar Furnace” that used mirrors to concentrate light on a central point, and which could melt metals.
Incidentally, although you can use a nmjumber of people holding mirrors to do this, the references to Archimedes seem to specify a fixed set of mirrors. It was another ancient, Proclus, who was said to have equipped individuals with separately movable mirrors. Nevertheless, two books on ASdaptive Optics cite Archimedesm, not Proclus, as the unofficial Father of Adaptive Optics.
And, as I recently noted in another thread, there are easier and better ways of siting those mirrors than looking for the spot, or even what Sapo suggests.
I myself wrote a piece about this for an MIT magazine. My final judgment was that it was certainly possible for Archimedes or Proclus to have done this, but I strongly suspect the story is apocryphal. There are easier and more reliable ways to set fire to a ship.
Here’s Mythbuster’s own follow-up. They still maintain it’s busted:
So, not a wet, moving, replica of a Roman ship and quite possibly using better materials than Archimedes had.
Sakkas burned dry plywood on a floating, stationary rowboat. Not a rapidly moving galley, much easier to burn materials, and the target was kept away from the water.
I’m going to go out on a limb and say that they aren’t constructing it out bronze age materials.
I should add that Sakkas did do many things right that a lot of other people who have attempted to duplicate the mirror have not. Sakkas did use a large number of people with bronze age reflectors and at least he put his target out on the water even if it was just floating there. It was an impressive effort.
Your reading may have been too hasty. The results weren’t similar at all.
Mythbusters:
-Plain cotton: 5 1/2 minutes
-Cotton with treatment identical to lower half of Hindenburg: 2 minutes 26 seconds
-Cotton treated as upper half of Hindenburg: 5 minutes 25 seconds
Dessler:
-Plain cotton: 33.5 seconds
-lower half of Hindenburg: 55.7 seconds
-upper half of Hindenburg: 68.3 seconds
Obviously they used different sized samples, so setting that fact aside, in the Mythbusters experiment, one of the doped samples burned much faster than untreated cotton, whereas in the Dessler paper, both doped samples took much longer to burn than untreated cotton. They in fact got the opposite result. Remember that the point of the experiment is to see if the doping compound contributed to the fire. If it actually retards fire, then that’s very, very significant. The experiment documented in the Dessler paper was repeated several times for accuracy. The fact that the Mythbusters got the opposite result indicates that either they should have repeated it, or they somehow didn’t use the same materials, or they used different methodology, or the narrator explained their methodology incorrectly.
Yeah, I would assume they did some research before they started. I’m surprised they didn’t mention it on the show, especially considering how different their results were.
At any rate, if they had scaled up the untreated cotton experiment, it would have answered a lot of questions.
So was anyone else confused about how they put hydrogen into the scale model?
From what I could tell, they were diffusing low concentrations of H2 through the model, then letting the hydrogen/air mixture ignite.
But didn’t the real Hindenburg have almost 100% hydrogen? And 100% H2 is not only not explosive (upper explosive limit for H2 is about 75%), but probably not even flammable (at least until the skin goes and some air can mix in).
So their scale model actually had better conditions for the hydrogen to burn than the real Hindenburg, no?
I believe I remember them saying they did it that way because if they simply filled it with hydrogen and ignited it, it would have exploded. When Adam tried to do a small-scale test, the hydrogen did explode.
Isn’t it commonly believed that the gas bags on the Hindenburg ruptured? So wouldn’t the hydrogen have leaked out and mixed with the surrounding air? Wouldn’t that be similar to the way the Mythbusters re-created it?
Quit moving the goalposts, Just Some Guy – I’[m commenting on the Mythbusters failure (and the more recent MIT attempt) to duplicate the experiment – in the recreationsd I cite, they used far fewer than 10000 mirrors on a target circa 150 feet away and burned it. The Mythbusters were trying to do something pretty much the same, but failed, and shouldn’t have. Nobody was attempting to burn anything different.
And if you were in Archimedes’ time, using Bronze age materials, you certainly could build a set of shield/mirrors that could duplicate the effect of modern materials – polished bronze is wonderfully reflective – and it is possible to maintain sighting on a moving target using methos I’ve described more than once on this Board. And you’d be an idiot to aim at a wet hull while you had those dry, big tantalizing sails and upper deck structure to focus on.
But then, as I’ve also said in every post, I strongly doubt that Archimedes (or Proclus) ever actually did this. The tendency to exaggerate their achievements was strong, and there are much more practical ways of bringing down a ship.
In what way is pointing out that the “successes” you mention are much easier things to do “moving the goal posts”? The Mythbusters episode was not “Is it possible to burn something with a parabolic mirror?” or “Is it possible to burn something far away with a parabolic mirror?”, it was “Could Archimedes have burned an invading Roman fleet with a parabolic mirror?” Setting much easier goals is not duplicating the situation. To quote you earlier in this thread:
But no one has duplicated it. The most that has been done are dramatically easier accomplishments than what they were testing.
I’ve read an awful lot of complaints about this episode and pretty much every single one boils down to the person complaining not paying attention to what was being tested.
