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/sci/ - Science & Math

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2716134 No.2716134 [Reply] [Original]

This may be a /k/ question is essence, but those guys are generally not smart enough to answer anything beyond their direct physical experience. So here goes.

The idea struck me that one might be able to construct a weapon that uses a liquid propellant rather than the solid propellants of current ammunition.

Gasoline is of course on of the first liquids that might spring to mind. It is high in energy. But I wonder if there are other, even more powerful liquids or liquid compounds that one might use. Preferably it should expand quickly, be energetically "dense" and hopefully be low on residuals (as more residuals = more cleaning and more prone to malfunction).

What does /sci/ suggest?

>> No.2716150

The problem you have is with ignition.

Guns use gunpowder because : a) its a contact explosive so no need for any fancy ignition techniques b) its relatively stable for storage and transport.

Why would you try gasoline? Its about as stable as gunpowder but harder to store and not a contact explosive... I currently dont know of any contact explosive liquids that are not batshit unstable.

I mean, what benefit are you actually saying you get out of using a liquid?

>> No.2716148

rockets

>> No.2716153 [DELETED] 

>>2716134
erm, it sounds like you are thinking of a flamethrower, and if so, you are fucking sick.

apart from that, i dont see how liquid amunition would work at all...

>> No.2716156

The future of weapons will be those BFC (big fucking capacitor) guns you see on youtube


>>2716148
/thread

>> No.2716160

No liquid explosive could be as dense as you.

>> No.2716168

>>2716150
>>2716148
>>2716153

These replies have nothing to do with my question.

I understand the problems and issues involved. My question is neither practical nor technical. It is chemical.

Are there liquids that have more energy than gasoline, expands faster, and yet leaves less residue?

>> No.2716174

Nitroglycerin ;)

Then there are the water-jelly explosives that have become so popular lately.

But the problem with liquid propellants is leakage and tendency to have high brisance, ie. it shatters the barrel and/or projectile rather than pushing the projectile out of the barrel.

Gunpowder is a low explosive precisely because exploding barrels are usually frowned upon.

>> No.2716186
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2716186

>>2716168
hydrogen, you could simply make a 2 chambers with H2 and O2, let only 1 into a container, seal it off then open the other and spark it.

problems are that the containment of the liquids would probably be way too heavy to carry, ps (liquid hydrogen and oxygen are really dangerous and flammable)

>> No.2716187

>>2716174
Now we are getting somewhere.

Ah, so what you say is that what I want is a slow-expanding liquid. But one that still needs to be energetically dense so one does not need to lug gallons and gallons of it.

Nitroglycering... well, may not be optimal.

>> No.2716210

>>2716187
What you would need is a liquid that has oxidizer in itself, like gunpowder does, and which conflagrates rather than detonates, again, like gunpowder does.

You might be best off with some variation of the water-jelly explosives. Though they aren't single liquids, but rather a mix of a liquid agent, solid agent and a gelatinizing agent.

Why do you want liquid propellant, if you don't mind my asking?

>> No.2716212

>>2716168

My reply had everything to do with your question fucktard.

"I currently dont know of any contact explosive liquids that are not batshit unstable. "

And Im a Chemist. So kindly fuck off.

>> No.2716215

>>2716210
>>2716174
Well, fuck, I of course meant water gel explosive, not jelly.

>> No.2716225

>>2716187
You want something that doesn't explode fast as fuck, brisance is how fast the pressure rises, so if it spikes to maximum pressure in a picosecond you're doing it wrong.

As for energy density of fluids, gasoline probably have a higher density than gunpowder and most other explosives, be they solid or liquids. This because gasoline does not contain its own oxidizer. This little problem could of course easily be compensated for by using atmospheric oxygen. So your gun, if using gasoline or something without oxidizers would have more or less the same components as an internal combustion engine, unless you are happy with a manual reload single shot gun in which case you have a spudgun.

>> No.2716230
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2716230

Since this is a gun technology thread, I'd like to ask a somewhat related question as well.

It's about railguns. Now, as far as I've gathered, railguns generally work with electromagnets, but is there any particular reason why you couldn't build a rifle from just normal, extremely strong magnets? Line them up along the barrel of a rifle, then all you'd need to do is pull the trigger that'd bump the bullet in the chamber a bit forward so that the magnets start to push it forward. No explosion required, presumable not much noise produced. I figure the major con of this would be that you'd need to manually load a new round into the chamber, but for something like a sniper rifle, wouldn't this theoretically work just fine?

Terrible illustration related.

>> No.2716240

>>2716230
Because the magnets would first accelerate and then decelerate the bullet, resulting in a net gain of 0 force on the projectile.

The reason for using electromagnets in a gauss gun is because electromagnet can be turned off once it has accelerated the projectile.

Also, railgun |= gauss gun.

>> No.2716241

>>2716230
The magnets need to be turned on in front of the bullet, and turned off when the bullet reaches them. It's a wave effect. So if they were all static magnets, the bullet would just stick to the first magnet, and you'd have no gun.

Also, that's a linear accelerator, not a railgun. Railguns have the projectile in direct contact with the rails, and the electron flow through it is what causes the magnetism.

>> No.2716242

>>2716212
>"I currently dont know of any contact explosive liquids that are not batshit unstable. "

Thank you, that is a better answer. But still I am not looking for contact-explosives. I have a new kind of electrical ignition system that should work just fine (with a bit of tweaking once a suitable liquid is settled on).

>>2716210
>Why do you want liquid propellant, if you don't mind my asking?

I have come up with a completely novel mechanics for constructing a automatic/semi-automatic firearm. It is quite unlike anything tried before and will give unprecedented performance on several measures. Obviously I will not go into detail on the mechanics.

It may be that the optimal way to implement this mechanism is with a liquid propellant. So I am looking for ideas, and I find that the beginning of a process like this, the width of competences usually present at /sci/ often provide me with good, divergent ideas that I can examine more closely if they seem fit.

>> No.2716245

>>2716240
>>2716241
Right, railgun was the wrong word. Guess I should've used gauss rifle / magnetic linear accelerator instead.

Basically, I was just thinking of something along the lines of this:

http://scitoys.com/scitoys/scitoys/magnets/gauss.html

Except stronger & bigger and more gun-looking.

>> No.2716249

>>2716245
And actually, now that I re-read this, I realize it's not the single ball you place in the beginning that gets shot, it's the last one... Derp. So loading the thing / resetting the shooting state would be even more bitchy.

>> No.2716252

>>2716241
>>2716240
noobs dont know how magnetism works.
its not practical because of the energy usage, epic heat creation melts metal conduits, eroding them.

>> No.2716255

I'd just think that a liquid propellant would be less efficient, and you couldn't pack as much in the same space as you could a solid propellant unless the liquid manages to be denser than gunpowder

also railguns fucking suck

>> No.2716264

>>2716241
So basically a maglev train but for bullets...

What you're describing is basically a multi-stage coilgun, but not as good.

>> No.2716270

>>2716245
I was sure you got the idea from that page. But the problem with that setup is that once the energy transferred from magnet-to projectile-to magnet rises high enough, the magnets start to shatter. Neodymium magnets aren't too tough and you can usually break 2-3mm flat deodymium magnet in half without tools.

You might use a kind of setup in your pic if you can construct a mechanism that very quickly moves the magnets away from the barrel in sequence as the projectile passes them, so that as the magnets are further away, they don't decelerate the projectile as much as they accelerated it.

And believe it or not, I have no degrees in any field whatsoever.

>> No.2716273

>>2716255
>you couldn't pack as much in the same space as you could a solid propellant unless the liquid manages to be denser than gunpowder.

Well, that might be wrong, but cuts to the core of the question. What I suspect is that a liquid propellant could be more efficient both in terms of space and weight provided that one finds the right one.

>> No.2716276

>>2716270
>>2716245
cezch it
http://www.youtube.com/watch?v=6mobpTrl7cA

>> No.2716281

>>2716273
well, find one and there you go, even in conventional firearms your liquid propellant is better.

However, it's really important that you find such a substance, AND that it be as cheap as gunpowder (unless you have some sort of caseless shit with a tank of propellent in the stock or something ridiculous like that)

It'd also have to be pretty viscous lest it leak out of the rounds and fuck up the gun, too

>> No.2716282

>>2716242
The fact you think gasoline would make an appropriate propellant for a firearm indicates this post is horseshit.

>> No.2716285

Why do people use the learn when they mean teach.

Charles Darwin will TEACH you origin of the species*

>> No.2716289

>>2716282
Yeah, isn't gas pretty slow burning? You'd want something that flares up nice and fast

>> No.2716296

>>2716285
Because of the context. In this instance it reflects the redneck way of speech used in the Eastwood film from the poster of which this image was shooped.

>> No.2716304

>>2716289
the reason gasoline usually burns slowly is the surface area, ie. as a liquid it has low surface area and can only burn so fas. But if you aerosolize it, like what happens in a combustion engine, it can burn extremely fast (can't detonate IIRC).

So for your gun, using gasoline really would require the use of an atomizer nozzle to spray the gasoline into the combustion chamber so it can mix with oxygen (atmospheric or bottle) and then be ignited to produce a fast conflagration.

>> No.2716309

>>2716304
... Which seems hella inefficient compared to just using gunpowder with is already all granulated and shit

>> No.2716314

>>2716282
Why are you at /sci/ if you cannot into reading? I never say that I want to use gasoline. If you read the original post you will see that I use it as an example of liquids that it are high in energy. Also, the context and the fact that I specifically ask for other compounds *should* lead you to the conclusion that I have no intention of using gasoline.

Now go back to third grade.

>> No.2716327

>>2716281
Like I said, I will not go into the specifics of the construction. But rest assured that there is no cannister in the stock.

>> No.2716334

>>2716327
You'll have to if you want an answer to your question. I don't think anyone ITT will patent your retarded ideas before you can

>> No.2716337

>>2716309
I know, I've just been offering OP my knowledge and trying to come up with solutions for people, instead of going "just use gunpowder lol".

If you can't help, why post?

>> No.2716347

>>2716337
I'm trying to help by saying "No, that's dumb"

you'd probably be better off using liquid oxygen or something to propel shit in what's basically a very large air rifle (which isn't *that* crazy, even a cheap rifle will fire a .177 pellet at like 800-1200 FPS, and some even come in .22)

>> No.2716353

>>2716314
Why are you getting on his case about not into reading when you cannot into typing sentences?

>> No.2716360
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2716360

>>2716334
What I can say it that on possible solution that I am looking at is using a liquid propellant used either as an aerosol or mixed with some other reagent in a chamber, and then ignited either with either: electricity, heat, or even a small solid primer.

The key characteristics I am looking for are that it is liquid, not unstable in itself, does not leav a whole lot of residue, and very dense in energy.

I understand that it is not good if it expands too quickly, but then again there may be ways to adjust the rate of expansion with additives.

>> No.2716370

>>2716360
Look up potato guns, because you are describing a typical potato gun.

>> No.2716378

>>2716370
I have, and no I do not intend to even try to build an automatic assault-rifle powered by hairspray.

>> No.2716409

>>2716378
If you really wanted to, you could, though.

It'd basically be an airsoft rifle except instead of air or co2 or whatever, it's something flammable that you ignite as it enters the chamber

>> No.2716416

>>2716409
And that would go even better if you had a better propellant than hairspray. Hence this thread.

>> No.2716460

Ok. Ill elaborate.

So - you want a compound that is a liquid, a powerful explosive and leaves no residue...

A good explosive has a few things in it - you want the oxidant present and you want the products to be gaseous, preferably nitrogen - this gives you an explosion which is incredibly entropically favoured and gives massive, rapid expansion of gases ie. the explosion.

A good example is RDX http://en.wikipedia.org/wiki/RDX - Youve got oxygen, youve got nitrogen, its gloriously simple. Nitro groups (NO2) are your best bet for a good explosive.

However, compounds with Nitro groups are invariably solid - as a chemist, if I want to make a structure crystaline ( to get an XRD of it) I shove a nitro group on it. You *can* get liquids with nitro groups, but they tend to have long carbon chains, which makes your explosive poop (takes way more effort to oxidise a bunch of carbon to CO2).

I think youre asking for something that does not exist

>> No.2716576

>>2716460
Thank you for an excellent answer anon. Now that this has been made clear, I can look for other solutions to the problem.

>> No.2716592

>>2716576

Dont get me wrong - it may very well exist - Im not an explosives expert - but it sounds unlikely.