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-   -   Propellant energy density question (http://www.firearmstalk.com/forums/f30/propellant-energy-density-question-92468/)

NukeEmAll235 06-18-2013 09:42 AM

Propellant energy density question
 
Here's something Witch I find interesting. A normal .50 bmg cartridge has volume for the powder about 20ml. The smokeless powder is about 15g witch at 6000joules/gram is 90 000 joules of total released energy, about 20 000 of witch become muzzle energy.
A 20ml case can hold organic nitrate compounds(similar to smokeless powder and nitroglycerin) with about 200 000 joules. Problem-making it detonation resistant as the smokeless is more difficult.
The same 20ml case can hold about 400 000 joules of metal powder enhanced propellant(like in rockets). Problem-heavy barrel erosion due to the high temperatures.
The question is, why humanity is still bothering with these low energy density fuels. The high energy density will allow for carrying much more rounds. Each shot to be cheaper, less brass, less transport costs. The chamber will be with less inner diameter and will have thicker walls for the same size. High energies will be possible without bottle neck.

gunnut07 06-18-2013 10:30 AM

Because it's what works.

It doesn't just matter on how much propellent you can fit in the case. The metal powder you talking about over 4 times more powerful 4.44444 to be closer to exact. So you are going to need a lot less. Plus now you have to account for the volume of air in the case as the more open air space will allow for the propellent to burn faster. If it burns too fast it then becomes an eraser and erases your FACE.

Smokless powder is great it works it is easy and cheap to produce and well IT WORKS.

NukeEmAll235 06-18-2013 11:21 AM

Quote:

Originally Posted by gunnut07 (Post 1279627)
Because it's what works.

It doesn't just matter on how much propellent you can fit in the case. The metal powder you talking about over 4 times more powerful 4.44444 to be closer to exact. So you are going to need a lot less. Plus now you have to account for the volume of air in the case as the more open air space will allow for the propellent to burn faster. If it burns too fast it then becomes an eraser and erases your FACE.

Smokless powder is great it works it is easy and cheap to produce and well IT WORKS.

I never meant using high energy propellant in existing weapon.
For example .22lr case filled with such high energy density propellant can be two times more powerful, yet maintaining the small size. Also, you don't have all this stuff(H2, CO, CO2, soot, NOx and what not) that comes out of the barrel, burns in the air and creates flash and smoke. Only the high velocity round and little amount pure H2O, N2 and CO2.
Imagine the power of 4.630mm with .22lr and less smoke and flash.
Black powder also worked once, but the smokeless is much superior.

robocop10mm 06-18-2013 11:54 AM

As I am not a chemical engineer, but my grandfather was, I cannot answer this one. I am willing to bet the powder companies have spent a significant amount of time and money on this very issue. If they are not using it, it is because it does not work

spottedpony 06-18-2013 12:14 PM

Quote:

Originally Posted by NukeEmAll235 (Post 1279646)
I never meant using high energy propellant in existing weapon.
For example .22lr case filled with such high energy density propellant can be two times more powerful, yet maintaining the small size. Also, you don't have all this stuff(H2, CO, CO2, soot, NOx and what not) that comes out of the barrel, burns in the air and creates flash and smoke. Only the high velocity round and little amount pure H2O, N2 and CO2.
Imagine the power of 4.630mm with .22lr and less smoke and flash.
Black powder also worked once, but the smokeless is much superior.

Another issue is the current technology in projectiles. Hunting rounds for example would need a design to tolerate the much higher velocites and still provide proper expansion without doing extreme tissue damage. That in itself opens up another can of worms in that the higher the velocity the more damage done, all other factors being equal.
Higher velocities will also create more heat which (other factors aside) may well cause a meltdown of the bullet traveling down the bbl, or cause a projectile to come apart in mid air prior to reaching the target.
Case in point, try loading and firing a thin shelled light hollow point bullet designed for a .222 in i high velocity .22 such as a 220 swift or 22-250, both of which can reach velocities of 3500 to 4000 fps. That bullet will come apart before ever reaching the target.
Lead projectiles would be a thing of the past as velocities would be much too high. At best you'd see extreme bbl leading, at worst, again projectile meltdowns.
Black powder still works, it may not be as clean, or as near maintence free as smokless powder, but i still wouldnt want to be on the recieving end of a shot fired at me.

c3shooter 06-18-2013 12:21 PM

First, you have sunk costs in not only the production lines, but in existing firearms. It may be that another road would get us there, but we are already well down THIS road. What would you do with the MILLIONS of .22 firearms that already exist?

Second, the goal and purpose of gunpowder is to deliver a pulse of expanding gasses, not a shock wave. There are some fairly exotic explosives that have an energy density and VoD MUCH higher than smokeless powder- however, they are fairly useless as a propellant.

Converting a metal to plasma gives far greater expansion that a chemical explosion (about 25 X greater increase in expansion), but again, the pulse is the wrong wave form to ideally move a bullet

NukeEmAll235 06-18-2013 01:12 PM

But they develop new cartridges all the time. By far I don't mean this concept as a way to obtain super high velocities. I mean to obtain standard velocities without bottleneck and large case volume or let's say 7.62x39 to have energy nearing 7.62x51.
Smokeless can detonate and if it does in the chamber, it won't rip it open, but rather pulverize it.
May be after all the gun community is ultra conservative, they won't even embrace the idea of .45 GAP much because it's new standard and wears the gun faster, and it's to be expected, it'll take time for the manufacturers to even consider making such new cartridge and weapons.

nitestalker 06-18-2013 01:36 PM

You should consider studying internal ballistics before condemning the ammunition industry. The thin walled cases that allow the arms to be portable and primer ignition in a rim fire would be only a few factors. ;)

NukeEmAll235 06-18-2013 03:41 PM

I don't see what the case thickness and primer type have to do with the energy density of the propellant.

JWagner 06-18-2013 05:12 PM

In dealing with a smaller charge weight, you increase the inconsistencies in the charges. Imagine that your production process can control charge weight plus or minus 0.1grain. That 0.2 grain variation will be a bigger percentage of charge weight with the smaller charge. That would affect the consistency of muzzle velocity, which would affect accuracy. This is sometimes called the "tyranny of small numbers". Smaller is not always better.


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