Anything can be used as a weapon if need be: A person in my story uses a big steel thermos in a fight. How could she beef up the thermos to keep using it as a weapon.
A real life story.
Back in a high school, my friends and I were very much into science, experimenting with a lot of different things. Once on a winter morning, my friend and I procured about one liter of liquid nitrogen, which my friend poured in his thermos and carefully put in a gym-type bag. We happily walked home on a snow packed sidewalk, until I, as it happens, slipped and fell.
Unfortunately, my leg kicked my friend's bag in the process, and that's wasn't even a hard kick. However, the bag quickly came alive with an angry hiss. Feeling that this hissing does not portend anything good, my friend put the bag on the snow and backed away from it. I could only watch what was happening while laying down.
About two seconds after the unfortunate kick, the bag exploded. Curiously, the bag appeared mostly intact after the explosion, however, it was pierced by countless tiny shards of glass which peppered the packed snow around us in a shiny circle. Neither me nor my friend got any injuries - I credit it to heavy winter clothes that we were wearing. Inside the bag, plastic thermos was shattered to pieces, and the inner mirrored glass vessel had become the shrapnel which shot through the bag's fabric.
My friend and I were quite amazed about the explosion - after all, creating a big explosion in which no one gets hurt is one of the top things on the mind of a school student.
Nitrogen is a pretty safe substance. There are many things which are relatively safe at cold temperatures (like oxygen or nitroglycerin) but create a lot of trouble when quickly heated. Contact with the snow heated the liquid nitrogen enough that it quickly turned to gas, which subsequently expanded with enough pressure and velocity so as to be mildly explosive, resulting in a shattered glass inner vessel, which became shrapnel-like.
Because the liquid-to-gas expansion ratio of nitrogen is 1:694 at 20 °C (68 °F), a tremendous amount of force can be generated if liquid nitrogen is rapidly vaporized in an enclosed space.
What you want to make is a meteor hammer.
If all you've got is a Thermos and a zombie problem, you need more force and more range. The meteor hammer is a classical Chinese chain whip designed to smash archers and infantry hiding behind personal or rolling shields. Specifically, you want the variant known as a single-headed meteor hammer. That sound cool enough to you? Let's begin.
Force is equal to mass times acceleration (F=ma).
Velocity is the result of acceleration over time, relative to a reference point.
When you hit someone with an object, they accelerate. If they were indestructible (a perfect, inelastic, "rigid body" in physics), and caught an incoming projectile, the combined target-projectile system would have a velocity that is the result of the projectile decelerating as the person accelerates, until the person-projectile system reaches a common velocity.
If they did not catch the projectile, some of that energy would remain with the projectile as it deflected (velocity vector changed), ricocheted (velocity vector changed, and reduced as some energy is converted into rotational energy and deformation), or pierced the target (losing energy to friction, deformation, etc).
But past a certain amount of acceleration, especially when a small contact area means you have a large acceleration gradient, bone and tissue simply fail, and when that happens, you get massive damage.
So, if you have an object of limited mass, and your combatant can only produce a limited amount of force per unit time, what you really want to do is use that force to continuously accelerate something, so that you can build up a larger amount of energy for an attack than a simple punch can deliver.
This is the logic for using a flail, whip, or morning star as a weapon. Now, light whips are actually a little more involved; properly used, the tip on a long whip can exceed the speed of sound ("cracking" a whip), allowing a rawhide whip to cut fabrics, or a metal-tipped whip to chip and shatter brittle swords.
Provided your fighter can find appropriate rope, chain, steel cable-- or, an interesting Chinese variant, ring-joined steel bars or plates-- in a good length, this is an excellent option. Your clothes and/or environment should be able to provide something. Consider using a belt, braided shoelaces, braided cloth strips, animal hide, etc.
The size and weight of the mass on the end of a classical meteor hammer is not too far off from your thermos. Still, the thermos is pretty heavy. This is a weapon that will take significant strength and practice to use masterfully, but should be manageable early on. In particular, the user can take up most of the slack for close combat (usually by wrapping the cable around the forearm), yielding a weapon more like a flail, which is still quite effective.
Here is a video of some of the moves available with this weapon:
The weapon's effectiveness, intimidation, and danger to the user all derive from the same thing: its unpredictability. When swung in a circle, or when wrapping around a weapon or attacker, its motion is easy to understand. But when snapped (pulled back at the moment the cable becomes taught) or bound (interrupting a wide swing with the hand or forearm), timing is critical.
Likewise, note that many of the advanced techniques involve moving the chain around more than one pivot at once. This starts to look a lot more like a double-pendulum, a simple system with notoriously hard to predict motion, whose distal movements are extremely sensitive to small variations in control.
The major technique classes are:
Grapples - the weapon is swung around a limb or weapon, converting the angular momentum of the swing into rapidly-increasing angular momentum around the target. Because the radius decreases, the speed of the final wrap can be sufficient to crush a hand, ankle, etc.
Slams - the weapon starts behind the user, and is hurled in a huge, powerful arc over their head, down onto the target. A devastating sneak attack, but easy for an alert opponent to dodge. Likely also suitable for defeating a locked trunk or floor grate.
Swings - Side attacks. Difficult to execute, but excellent for discouraging secondary attackers.
Throws - the weapon is thrown, like a rock, shotput, or discus, but can rapidly be retrieved from a safe distance.
Whips - in your case, with either end of the weapon, depending on material used for the chain, and what you wind up using for a handle. The timing of this attack is less predictable than a throw, so defending against it requires excellent reflexes.
One of its more unusual properties is that it can allow a meaningful defense after getting knocked down on the ground-- that is, from a prone position-- provided the user is not already grappling. See the video above for an example of that. If swung with enough strength and authority, the weapon can be used to "clear its orbit" in the middle of an advancing crowd.
In short, it's an unusual, exciting, and dangerous weapon that can be used with either rage or finesse, that an unwilling wielder might very well find themselves gradually mastering out of necessity.
Worth a look!
As I understand the question, there's a character who uses a thermos as an improvised bludgeoning weapon in a pinch against zombies, and continues to use the weapon after that, as their weapon of choice.
This question suggests an off-the-wall but practical low-science universe (a la Douglas Adams or Pratchett); where a rationale just needs to stand up to narrative logic, not necessarily to scrutiny with hard engineering and science.
To be narratively believable, I think bludgeoning weapons need a few basic elements: practicality, integrity, mass, balance, and reach.
Practicality Assuming the character places a British level of importance on the role a nice hot cup of tea in survival, and has a generally non-combat role in the party (healer, grannie, wise woman, etc), they'll always have a thermos and kettle to hand, as well as some tea. And a teaspoon, obviously. Of these things, the thermos is the only one that can immediately be used as a weapon, so kinda makes sense in character, in extremis.
Physical Integrity. You can't beat someone up with a rotten stick. While the glass-lined, plastic thermos of yesteryear was a useless beast even for such purposes as "holding warm tea" without lacerating the drinker's innards with shards of glass, the more modern but still humble metal-lined thermos can take one heck of a beating.
Mass Even empty, a double-lined metal thermos has decent heft, and a good edge on the base. Full, you're adding a good chunk to its weight. Assuming the above 2l model, you can add 2kg of liquid, or about 4kg if you add sand in with the water (wet sand has a mass of a little over 1.9kg/liter). Few who've carried even a 1 litre thermos, like anyone who's carried a 6-cell maglight, will have much doubt about its ability to cause blunt trauma.
Balance Here it starts to have problems. The grip's all wrong. The handle's on the side. The whacking end is likely going to be the bottom, but there's nothing on the cap to hold it by - it'd just be knocked out of any hand that tried to hold it. So, at the very least, it needs a handle.
Reach And here, too, it falls down. It has no more reach than smacking someone over the head with a flowerpot, so is likely to be no more use.
I think @John's on the right track here, it needs a long handle to resolve both the problem of balance and of reach. His suggestion for telescopically clubifying it may work, though I feel it'd be a hard engineering problem to make that work and still have both a functional thermos, and functional club.
Instead, what if the walking-stick of the wielder had a thermos cap on the end, as the handle? Then to weaponize stick plus thermos, simply unscrew the cap off the thermos, screw the walking stick into the top instead, et voila, thermos-club.
There's also the possibility that the insides could be filled with something harmful to the undead - holy water, perhaps (which maybe does more damage when heated, in which case, at a pinch, you can also conveniently turn it into tea!) Or scalding water, liquid nitrogen, whatever zombies can be harmed with by sprinkling them lightly with in this universe.
In that case, you'd need to use it more like a censer, to sprinkle the holy water at the undead. Poke a few holes in the inner cap, tie a rope to he handle, and you can maybe spin it around your head, sprinkling all around.
If the "big thermos" is actually a steel canister of exactly the right proportions, you can use it like a gauntlet. Put your hand inside and tighten your fist; the hand is now blocked inside the cylinder, which covers the arm up to the elbow. Some canisters can weigh up to three kilos.
While the zombie scratches uselessly at the cylinder, you can swing it quite handily, pardon the pun, and cave its face in. Zombies are no more impact-resistant than normal humans, and three kilos of steel punch can quickly take the fight out of one.
Later, you can screw some bolts in the steel and file them to points, and you've built a sort of gauntlet plus spiked mace.
Not really recommended for melees though.
turn it into a collapsable club. Anyone with some mechanical skill and machine shop could manage this. It just needs to expand is several telescopic sections. you could even cannibalize a collapsible baton for parts. There is even a RWBY character that has one of these.
Of course it won't have much in the way of storage capacity after this. but if you give up on it holding liquid you can make a pretty sturdy club. Plus if your hunting zombies a club is one of the better weapons you can have.
Alternatively use the thermos to make a silencer, it just won't work for long.
It could be used to make an ad-hoc time bomb. Fill the flask with liquid butane or propane or a mix of the two and securely seal the cap in place. Put a lit candle on top of it and retire. Eventually as heat seeps into the flask over several hours the butane/propane will heat up and start to evaporate. The pressure will increase and at some point the top will be blown off by the butane/propane gas pressure and will be ignited by the candle causing a fire ball.
Alternatively fill with butane and seal. Tie some petrol soaked cloth around light it and (quickly!) drop it from a tall building on to the enemy below if it hits the ground hard enough the cap and or bottle will crack or leak causing an explosion.
If these options are not appropriate how about filling it with boiling water. Should remain an effective scolding agent for an hour or more.
Dewi Morgan outlines two problems with the thermos: balance and reach. Simple solution: The thermos was in a holder bag. The bag has belts/strips which change the balance and add reach to the improvised weapon. The bag could add to the durability of the thermos, in particular if we are talking about a good quality leather thermos holder. However, also note that the strips of low quality bag might not last much. As per fighting with it, I would expect it to be be similar to using a purse as improvised weapon.
Addendum: It is also lowers the control over the weapon. Did the character take some self defense course? Let us say the character took some self defense course.
how about strap or tied it with rope to ad it into flail (may or may not include the stick)
fill it with water,sand, or whatever thing that can be put into it to increase the weight.
after all other has mention that it far more practical to just use the stick rather than attaching stick to the thermos.
A thermos is unwieldy. There is no sure way to grip given the amount of force required of a blunt object, which also leads to the issue of not wanting to both be in close proximity and only have a loosely gripped blunt object.
Let's face it, the thermos sucks. It is best suited towards filling with coffee and reflecting on all the success the firearm had.
What you would really want to do is transform the thermos into, well, not a thermos. Let's make, a hammer.
- Remove the lid
- Fill the thermos a quarter of the way with dirt
- Crush the top three quarters into a handle
Probably not quite Mjolnir, but it should do quite nicely for prolonged bashing.
As an optional conversion from this point, crush the bottom part in a crevice to achieve a nice right angle for a hatchet-ish weapon.
This one is easy and even I might go for a thermos too (without emotional attachment). Drill two large holes close to the top and pass a chain. Then melt and lead, tin, or solder and fill your thermos with it, capturing the chain in the liquid. These metals have relatively low melting temperature, and very very heavy. The thermos she is using should be of extreme quality to withhold the forces but in the end she will get an extremely well crafted flail. If you use lead it will weigh 11kg (assuming 1lt) excluding the weight of the thermos itself. 11kg in such a small size that you could swing easily over a meter long chain would hit better than any other club you could come up with. Even if you go with solder, which is extremely easy to find and melt, you will still get 9kg.
Stuff the thermos with explosive.
Attach a fuse to it.
The explosion will fragment the steel case into shrapnel which will throw havoc in the surrounding of the explosion.
For additional bonus you can mix the explosive powder with other metal objects.
Or boobytrap it, using the lid or the dispenser as trigger for the explosion. When the thirsty enemy will attempt to check/use the thermos, will be blown up.
Thermos Spud Gun
Ok, so a level of handwavium is required here.
The basic principle behind a potato gun is that it has three parts - an ignition source, a barrel and a combustion chamber. A potato (or suitable projectile) is forced into the barrel, the combustion chamber is filled with a volatile propellant, and the ignition source ignites the propellant, sending the projectile out of the barrel.
In your situation, the thermos becomes the combustion chamber. Weld a steel barrel onto the open end of it (*being a steel thermos, it needs a steel tube). You'll want something that tapers the barrel down to a diameter around the size of a pool ball before having a smooth pipe around a couple of feet long. Then, drill a hole into the rear of the thermos, and screw in a piezo-style oven igniter.
You now have a thermos musket. Substitute the potato for a bunch of pool balls as I mentioned above (you may need to wad them with something to create a decent seal down the muzzle), and find some hair spray etc to use as your propellant.
There's a lot of additional maths surrounding the optimal diameter/length barrels to match a certain size of combustion chamber, but throw in that handwavium from before and start blasting your zombies in half with cue balls.
Once I was biking in the cold with a friend, and I put hot chocolate in a thermos. Considering it was only tap water on the highest setting of heat, the thermos did pretty well at maintaining a consumable temperature for the drink. Acknowledging this ability, I would personally add boiling water into the thermos or possibly even molten aluminum or solder depending on the material that the thermos composes of. This could be wrapped in a non-conductive yet heat resistant coating such as glue and saw dust, added with a layer of plastic wrap. Wrap it in ways that will continuously allow the opening and closing of the device so that you may sneak up on your enemies and dump surprisingly hot liquid on them whether its on their head, or tossed from a distance like a bucket of water.
Fill part of the thermos with liquid cesium at a temperature of, say, 80 C. Then you put a thin plastic lid over it such that there is a small gap between the cesium and the plastic. The part above the plastic is filled with water and you then close the thermos.
If you shake the thermos, the plastic separation between the water and the cesium will burst and you'll get an explosive reaction between the water and the cesium. The thermos will burst which will cause a secondary explosion due to hydrogen gas from the reaction escaping into the air and reacting with oxygen.
You can improve the design of this weapon by putting multiple alternating layers of water and cesium inside the thermos. You'll then get a far more efficient reaction between the water and the cesium. The reaction will continue for much longer after the flask is breached, yielding a much bigger explosion.
If she is very clever she can make nitroglycerin out of urine and some other stuff and perhaps it would be thermally stable inside the thermos and used as a huge grenade. Otherwise with urine she can make black powder and find some flint in the garden and mix up flint and black powed which whill explode when it hits something.
You can put anything in a thermos: hot oil, chilli powder, boiling chilli sauce, liquid nitrogen, and you can take out the protective plastic shell and have a glass thing which whill explode when it hits something releasing whatever is inside.
Fill the thermos with a hard vacuum and hurl it toward your enemies. The thermos will collapse under atmospheric pressure creating a loud and disorienting bang. Close enough to your enemies, the implosion can be fatal.
Use this moment to flee.
Alternatively, you could fill it with a high-pressure fluid and achieve a similar effect.