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Old April 2 2012, 10:45 PM   #27
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Re: Heads up! MYTHBUSTERS season premiere tonight at 9 Eastern!

Trekker4747 wrote: View Post
Works for me, I'd PM one of the TV/M mods to rename the thread something more generic. "Mythbusters Discussion Thread" or something.
Good idea. Maybe specifying it's for the 2012 season.

The Fire v. Ice myth was an interesting one to test but not surprised at the results. Though this is one I'd like to see them "ramp up" in a revisit. The problem I see even with the water Adam's device is still pretty much shooting a gas, the flame-thrower is throwing something with "substance" to it either the liquid fuel or the plasma of the fire, what's more is it's being constantly fed by the tank and the fire is always keeping the fuel lit as it exits the nozzle. It's like trying to stop a freight train moving at 80 mph with a puff of air.
From what I understand, there's relatively little actual plasma in a normal flame; it's mostly just incandescent gas. In this case, with gasoline as the substance undergoing combustion, the reaction products (the constituents of the flame) would be mostly carbon dioxide and water vapor, plus carbon monoxide if some of the combustion was incomplete. So since Adam's souped-up extinguisher blew out carbon dioxide and aerosolized water/ice, it was basically a duel between two clouds of nearly identical chemical composition, differing only in temperature and pressure. As you say, the stream of uncombusted gasoline from the flamethrower might be a factor, but it looked to me like most of the liquid was falling to the ground before it reached Adam's "little house."

You know, I never realized that before -- that flame is made out of the same substances that are generally used to put out fires. So "fighting fire with fire" isn't so far off, in a way. (And this is why fires generally don't burn long in microgravity. Without convection to spirit the hot gases away, they smother the ignition source and cut off its oxygen.)

They'd need a pretty supersized and well-thought out "fire extinguisher" to re-create the (obviously CGI) effect of the viral video.
CGI? No way. I've never seen computer animation that can so accurately replicate the fluid dynamics of fire or clouds, and there's no way some viral video creators could have access to such sophisticated tech if it existed.

I found the actual YouTube video:

The flame and vapor elements are definitely real, and mostly the illusion is created simply through editing and composition. There are only a few long shots showing the full scene of the flame stream and the CO2 cloud meeting, and the rest is close-ups of the individual "combatants" and the streams/clouds in midair. Classic old-school FX psychology: do just a brief shot to sell the illusion and then let the audience's mind fill in the rest. I think that for the long shots they probably filmed a smaller-scale pyro/vapor element and composited it into the scene, since the vapor cloud seems too big to be emanating from a normal fire extinguisher and I'm not sure the arc of the flamethrower stream is dipping as much as it should over that distance (see the shot at 2:48).

And the Mythbusters' approach was misleading, I think. They seemed to be testing whether the extinguisher could douse the flamethrower, but the video only shows it deflecting the flame and keeping its wielder safe until the flamethrower runs out of gas. And I think the results showed that to be borderline plausible, at least given a powerful enough extinguisher (and maybe a less potent flamethrower; Jamie's seemed to produce a much bigger flame than the one in the video).

On the Jr. team's efforts, I'm sort of surprised they didn't go with a robotic/RC rig to create the circular dust storm. Such a rig would eliminate the human element and wouldn't be as restricted by speed, etc.
But part of the movie myth was that it could be done by human-driven cars. It wasn't just the dust issue they were testing, but the whole scenario.

I don't see why the illusion would need to be addressed, it's the loss of the "magic" in movie making.
I would like it to be addressed because I'm interested in how special effects are created. And the Mythbusters have done that before with a number of their movie myths -- not only busted the depicted scene but explained how it was really done.
Christopher L. Bennett Homepage -- Site update 4/8/14 including annotations for Rise of the Federation: Tower of Babel

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