Episode 161: Blue Ice

Air Date: April 13, 2011

By intentionally causing a gas leak in a room and inserting a magazine in a toaster, it is possible to cause a large explosion (as shown in the movie Bourne Supremacy).

busted

Adam and Jamie began by placing magazines of various thicknesses in toasters and timing how long they took to catch fire. The thinnest and fastest to burn, similar to common newsprint or comic books, took roughly 2 minutes to catch a flame rather than the 20-30 seconds observed in the film. Small-scale tests with mixtures of methane and air indicated that a methane level as low as 6% (the bottom end of its flammability range) could trigger a noticeable explosion.

For full-scale testing, they built a replica of Jason Bourne’s apartment, including the toaster, magazine, and methane supply. Their first attempt at an explosion, using the circumstances shown in the movie, did not give any significant reaction, and the myth was declared busted. A second attempt with a higher gas concentration and a fireplace starter log as the ignition source led to an energetic fire, but no explosion. Adam and Jamie made one last attempt, using enough methane to achieve a 9% concentration (the center of the flammability range) and a set of fans and diffuser hoses to mix the gas and air thoroughly. This time, they were able to get one wall to blow out and set the apartment on fire.

If the contents of an airplane toilet are jettisoned mid-flight, they can freeze into a solid mass capable of inflicting severe damage upon hitting the ground.

confirmed

To set the stage for this myth, Kari spoke to an airplane technician and learned that although a pilot cannot dump the toilet mid-flight, the contents could leak out if multiple valves and seals failed.

For their tests, the Build Team made a small section of an airplane fuselage, including a lavatory service outlet (designed to suffer a slow or sudden leak, as needed). They took this rig to a wind tunnel at NASA designed for high-altitude simulation (including low air-temperature). When the toilet was dumped all at once, the fluid quickly atomized in the wind, leaving only a thin film to freeze on the fuselage. However, a slow leak allowed the ice to build up into a large mass that did not break loose until the rig “descended” (i.e. the air temperature in the wind tunnel was increased) to 12,000 feet (3,650 meters).

To determine the ability of such a chunk of ice to survive a fall to earth, Kari dropped a 35-pound (16 kg) block of ice from an airplane at 12,000 feet. Grant and Tory tracked it from the ground while Kari skydived. The block remained intact and embedded itself deeply upon impact, prompting the team to declare the myth confirmed, although unlikely due to the multiple mechanical failures needed to achieve the result.

14 Comments

  1. Steve says:

    In the “blue ice” story I noted one problem in the 12,000 foot drop test: the chunk of ice they used was a frozen solid hunk. However, the ice formed from a slow leak of the toilet system would probably not be quite so solid. It would probably form in layers and most likely have holes in it.

    I’m wondering how this non-uniformity would affect the result. I’d expect that winds as it fell to introduce stresses which would cause it to break apart into smaller chunks.

    • David M says:

      I agree. The irregular and jagged edges of the “blue ice” would offer resistance and would, most probably, break off as it fell at high speed and as the temperature rose. I don’t think that it would react the same way as the block of ice.

    • Jeff says:

      I agree, the ice sample was not consistent with the ice formed in the test at NASA. The ice there was layered and rough both of which would increase the effects of friction as the ice falls increasing the possibility or breakup during it’s fall.

    • John says:

      A couple of things on the ice issue… 1st, as mentioned before, the ice from the leak was formed over time in irregular layers. Trapped air in these layers form “faults” if you will. You can see how much air was trapped in the layered growth by its opacity… compared to the monolithic clear chunk dropped from the plane. Also, you must consider the shape. The ice from the plane was irregular and formed in a linear plane. This more than likely would affect how it traveled through the air in its decent. I would imagine a “tumble” would be present. On the other hand, the dense, smooth, Myth-Buster cannon ball would be less affected by air currents… and to compound on this injury they strapped on a streamer guaranteeing a straight, arrow like entry. I would bet the Buster missile impacted the ground at a higher velocity and with more momentum than would the lighter, more fragile and irregular toilet-asteroid.

  2. Tom says:

    In the “Bourne” story there was couple differences betwen movie and Mythbusters experiment. In europe insted 110V is 220V that twice much (ignition). Second difference is in construction of the buildings. In Mythbusters epizode, building was made from wood and drywall and explosion blow up side of structure. In europe buildings is made out of concrette and bricks so it is heavier and withstand Moore psi. We know More psi more BOOOM.

    • Olsem Wanem says:

      I disagree with your comment about voltage. The fire in the toaster is caused by heat, not by voltage. A European toaster will heat a European slice of bread at the same speed as an American toaster heating an American piece of bread. Voltage is irrelevant. Also, I don’t think a concrete building will produce more “boom” because it can withstand more pressure. That’s like saying. The concrete walls will withstand more pressure, and may cause the windows and doors to fail first, but the “boom” depends on the flammability of the fuel/air mixture, not the structure of the building.

    • Sam C says:

      The voltage is irrelevant. Ohms law tells us that Volts x Amps = Watts. A typical toaster runs 1000 W; at 120V it would draw 8.3A, at 220V it would only draw 4.5A. (European appliances are actually more efficient because they run on 220V.)

      • Mark says:

        All of the above comments about voltage/amperage/wattage are irrelevant as it was the burning paper in the toaster which was the ignition source!!!

  3. Spencer says:

    For the “Bourne” story, I think it would have been a better final test to construct a slightly tougher house with inner walls that could channel the explosion, and using the first tested magazine with a 12 min ignition time, let the house fill with gas until the magazine ignites. Then testing to see if the explosion would create a shockwave that could knock people down standing outside.

  4. RC drinker says:

    I LIKE THE MYTHBUSTERS!

  5. Rob says:

    What I want to know is, how did they get a toaster to “toast” for anything close to 12 minutes? Wouldn’t the MB lads have to repeatedly push the “plunger” down? This wasn’t mentioned in the show.

  6. Rob says:

    I am inclined to disagree with Steve’s original comment on “blue ice”. To me it would make more sense that as the “slow leak” formed in to a chunk of ice it would be rather solid. As the liquid hit the very fast moving air current it would become a very fine mist. I would think that because of this that the block formed on the leading edge of an exposed structure from this would actually be pretty dense. Unless for some reason the low pressure zone under the wing changed this somehow. I do not in any way claim to be an expert in fluid dynamics so I could certainly be wrong.

  7. ac220 says:

    I’ve seen results of a propane _tank_ explosion once. It was much, much more powerful than what they achieved on the show, or even than the prototypical scene from the movie — a section of a small brick appartment block was demolished to the ground, and the rest had huge cracks right through the brickwork.

    I think it’s partly because the tank was inside the building then the explosion happened (and did what overheated pressure vessels do) and partly that brick walls effect of Steve’s comment… But I’m no expert.

    • Nike says:

      They used methane instead of propane,
      Result seems to be very different.

      How are they sure that bourne’s house was
      methane instead of propane?

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