MakeShift Challenge: Zombie Attack: Most Plausible

Makeshift 25: Most Plausible: Patrick Tait
by Lee D. Zlotoff
Volume 24, 2010

There’s more than enough equipment to escape the hoard in a variety of ways. Anything from fighting your way out with a fully automatic nailgun with ghost ring sights and flaming armor made from duct tape, stove parts, and welding equipment, to a chainsaw-powered escape vehicle with axial mounted flamethrower and a multi-barrel electric ignition Molotov cannon.

That’s not what this particular MacGyver wannabe would do in a doomsday-level event. The standard plan for large-scale invasions, be they alien, communist, dinosaur, or zombie, is to die in the most badass manner my means may allow. Part of it is the philosophy of “Live fast, die young, and get a closed-casket funeral.” The bulk of it is the fact that any of the above invasions will cause enough damage to the world that I will not likely be able to read webcomics again during my lifetime, and a world without webcomics is not a world I’m willing to live in.

So:

My goal: Blaze of glory that will burn my memory in the collective unconscious of the zombie hoard.

My assets: the tools and materials listed above.

My liabilities: Severe time limit, at most an hour before the zombies break in and try to harvest my delicious brain-meat.

My method: Massive explosion.

I’ll get to the mechanics of blowing up the garage in a second; first I need roof access. Roof access gives me an observation post to time the detonation, a place to whang humorous or heavy objects at the dead, and a nice view in my final moments. Getting to the roof is easy, if there isn’t a circular saw or Sawzall among the tools then the chainsaw is a genre-appropriate option. The fact that the gas reservoir is empty is no problem, there’s a mower with half a tank left. If there’s no tubes available for siphoning, then unhooking the fuel line and running it to the chainsaw should do the trick. If neither option is available, pipetting using a short length of PVC pipe would work. It’s dangerous, stupid, messy, and carcinogenic, and you really shouldn’t do this in normal times. But these aren’t normal times, and this technique is entirely appropriate in a zombocalyptic disaster zone. Just insert the pipe into the tank, suck until the gas almost reaches the top of the pipe, cap the top with your thumb, and transfer.

So, how to make the most boom with the materials at hand? If this was Hollywood, all I would have to do is shoot the propane tank with the nailgun and the building would be leveled. If this was good Hollywood, I may have to dramatically light a match or strike a spark to get the gas to explode. If this was bad Hollywood, I’d be able to toss a match into the mower’s gas tank and jump under some wet blankets. The tank would explode a path through the zombies and I’d suffer a minor hair injury that’s gone three scenes later. This isn’t Hollywood. Setting a propane tank on fire will, at best, cause a small fire. Dropping a match into a gas tank will, more often than not, cause the match to go out. Hiding behind the wet blankets would make the cleanup of my corpse easier, that’s it.

Where Hollywood fails, fuel air bombs succeed. Take a flammable gas or a fine dust of flammable solids, mix with air, and ignite. The resulting overpressure wave can potentially be the most powerful explosion for a given size of bomb short of nuclear. Look up the MOAB or “dust explosion” to get a picture. My explosion will be based off of an oxyacetylene mix. I’ve got the oxyfuel welding equipment which gives me both the gas and an easy way to get the ideal stoichiometric mixture of oxygen to acetylene. Just pick the largest tip available, adjust the torch to a neutral flame at maximum output, and then strike the flame out by hitting the tip of the torch on the concrete floor. The welding kit is now leaking an explosive mix of gas, and the only thing between me and a flaming ball of zombie death is the time it takes to empty the tanks and a single spark.

Get out your slipsticks because this part holds the math. My garage is 20x12x10, or 2400 cubic feet (~70 cubic meters). When I was taught welding, it was on 210 ft^3 (7 cubic meter) cylinder, so that’s what I’ll assume I’ve got on me. That’s only 1/10th of the volume of the room we want to explode, so just letting the tank bleed will do us no good. Diluting the gas reduces the effectiveness of the explosion, to the extent that at low concentrations, it won’t burn. I need a container to hold the gas mixture until it’s time for the big boom. Camping equipment provides in the form of tents. Ripstop nylon isn’t entirely gas proof even without the windows and zippers, but if properly sealed, the leaks should be slow enough that it won’t significantly effect the power of our charge. So seal the flaps of the tent with duct tape, double tent it if at all possible, and slather a layer of oil over it to help seal the holes. The first balloons were just canvas sealed with tar, after all. For detonation, I can run a length of the PVC pipe from the tent up to the roof and drop a match down.

How much bang can we expect to get from our little experiment? This is a somewhat apples-to-oranges comparison, but we can get a Scientific Wild Ass Guess as to the force of the blast by comparing the energy to that of TNT. Acetylene has 56 megajoules per cubic meter, and we have about 7 cubic meters, so that grants us 392 megajoules of potential energy. TNT’s explosive force weighs in at 4.7 megajoules per kilogram, 392/4.7 gives 83 kilograms of TNT equivalent. The overall effect will probably be lower, due to lower explosive velocity and the garage walls dampening the force of the explosion, but I’d be confident that any undead abomination that’s in my yard will be put to rest.

There’s a couple of ways we can increase the lethality of the blast. The most obvious is shrapnel. Anything that’s sharp or painful can be placed at head level near the weak parts of the building such as windows, in hopes it gets launched into a zombie’s skull by the explosion. The propane tank can be cracked open, it won’t be a perfect mix like the acetylene, but it can’t hurt. Assuming zombies are attracted to sound (which is a semi-standard trope) I can set the laptop to play something suitably dramatic, rev the chainsaw a few times, and sing “Way-Hey and away we go, zombie killing, zombie killing!”* to the tune of the traditional maritime song “Donkey Riding.” While I’m doing that, I’d toss the various oil containers around in the hope that a slippery surface will slow them down. Molotov cocktails will be thrown just before I set off the gas, unlit for safety and to prevent scaring off the zombies. If I spot the neighbor who habitually lets his dog befoul my yard, I’d try and wing him with a thrown wrench.

When I’m done with prep, I’d start the welder up, make one last sweep for shrapnel or other things I can throw at the zombies and climb back up to the roof. When the tent is full or the gas runs dry, it’ll be time to make peace with myself, start my best maniacal laugh, strike up a match, and ride the fireball to my maker.

* The full song goes like this:

[chorus]

Way-hay and away we go, zombie killing, zombie killing

Way-hay and away we go, killing them damn zombies

On the night living dead

Smash those zombies in the head

Fill them ghoulies full of lead

Killing them damn zombies

[chorus]

Was you ever in your garage

Trapped by zombies, dead at large

Hungry corpse, Death’s entourage

Hoards of rotting zombies

[chorus]

Was you there in judgment day

Safe harbor is too far away

Grab your wrench, make zombies pay

The Alamo with zombies

[chorus]

Was you ever on the roof

Coz your house ain’t zombie proof

Drop a match it all goes poof

Vaporize them zombies

>> MakeShift 25: Analysis, Commentary, and Winners

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