Regarding artillery shells

bobus67

New Member
Greetings,

I just joined this forum hoping to get answers to a few questions that I've had for some time from people who are either military professionals or well-read hobbyists.

Q1: why is it that (at least as far as I know) artillery shells do not contain powerful plastic explosives such as C4, but rather more low-tech explosives such as TNT?

Thanks and... nice to be here!

- George
 

Todjaeger

Potstirrer
Greetings,

I just joined this forum hoping to get answers to a few questions that I've had for some time from people who are either military professionals or well-read hobbyists.

Q1: why is it that (at least as far as I know) artillery shells do not contain powerful plastic explosives such as C4, but rather more low-tech explosives such as TNT?

Thanks and... nice to be here!

- George
The question is simple, but the answer is a bit more complex.

First off, it really depends on what artillery shell one is talking about, who manufactures it, who the end user is, and for what purpose, all of these factors go into which explosive compound(s) are used in the explosive charge within the artillery shell.

The second thing is that often people are confused as to what explosives actually are. In the example you provided of C-4, while C-4/plastic explosives is indeed an explosive, the actual explosive chemical is RDX which is then mixed with other compounds to act as binders and plasticizers to provide stability and malleability. In that respect, TNT is more like RDX, as opposed to C-4. As a side note, RDX has also been used as the explosive filler in some ordnance, as well as in explosive mixtures like Torpex which also had TNT as a component.

Speaking more broadly about which explosive is selected and used for a particular role, there are a number of factors which are involved, only one of which is the energy output of the explosive itself. While TNT is not the most energetic HE, it is very stable, easy to use, and I believe comparatively inexpensive, whereas nitroglycerine, the first HE discovered, in pure form is still among the most powerful of HE, but the problem remains that it is also extremely unstable and reactive to shock when in liquid form.
 

Systems Adict

The Bunker Group
Verified Defense Pro
Greetings,

I just joined this forum hoping to get answers to a few questions that I've had for some time from people who are either military professionals or well-read hobbyists.

Q1: why is it that (at least as far as I know) artillery shells do not contain powerful plastic explosives such as C4, but rather more low-tech explosives such as TNT?

Thanks and... nice to be here!

- George
There are other aspects to do with the 'design' of the explosive element. C4 as stated above is a 'plasticised' explosive that can be shaped/cut up / moulded, or simply used as bricks. C4 is fast acting, so that its design allows maximum 'bang-for-buck' in a small space, to provide maximum effect.

Artillery shells (from a 0.22 round up to & including rounds such as the RN 4.5 inch), all generally use a primary explosive that detonates the secondary explosive.

In most shells that's a percussion cap, which is stable, but fast acting when activated. The secondary explosive is usually made up from 'grains' (little balls, or shaped grains, such as stars or tubes). Their composition (chemicals used to make up the explosive) are designed to release their energy potential slightly differently, so that rather than a single 'big-bang' like C4, they react with each other over a period of time (still in the thousands of a second), but it is controlled, so that the explosive force is contained within the structure of the shell casing, thus forcing the projectile out the end of the shell casing.

C4 can't be contained that way, due to the chemical elements & their reaction when it explodes (more 'power' produced from the chemical reaction at time of exploding).
 

bobus67

New Member
  • Thread Starter Thread Starter
  • #4
Thanks to both for answering. Let me see if and what I understood.

Todjaegeryou're saying that C4 may be more powerful than TNT but is also unstable and therefore not safe to use.Right?

Systems Adict, I have very little clue on what the point you're trying to make is, though I do understand what you're saying. What exaclyl would we lose if we used C4?
 

Todjaeger

Potstirrer
Thanks to both for answering. Let me see if and what I understood.

Todjaegeryou're saying that C4 may be more powerful than TNT but is also unstable and therefore not safe to use.Right?
No, not what I posted.

I will try to explain it another way.

C-4 or plastic explosives, is a solid mixture with a consistency similar to modeling clay which is quite stable, and is able to be easily molded (hence part of the name being plastic). The actual "active ingredient" in the explosive mixture, or otherwise the part which actually goes BANG, is the explosive RDX. Now RDX can also be quite stable, and provides a more energetic reaction than TNT and has been used as a component in explosive ordnance, but it is also more expensive.

IMO there would be no point in using something like C-4 in a warhead, because a warhead does not require that the explosive filler be able to be shaped or modeled, which are properties that C-4 after the binders are mixed with the explosive RDX.

Now TNT on the other hand, is an actual explosive just like RDX is, which starts out with a number of useful properties without requiring the addition of other compounds into a mixture. TNT itself is stable, and since it can be melted at a fairly low temperature (80 degrees C IIRC) allowing the resulting liquid to be easily poured into a variety of canisters, containers, molds, warheads, etc. This means that for the production of munitions, TNT works very well because it is easy to use, stable/predictable in behavior (meaning it will not go off when it should not, and will detonate when it should) and I suspect the cost of TNT is lower than a number of other explosives due to how long it has been around (~1860's).

TNT has started getting replaced for some roles in US service because there are newer explosive compounds which are 'better' for certain applications like HMX, or IMX-101, but something like C-4 would never really have been a realistic candidate for use in ordnance because of the properties it had.
 

OPSSG

Super Moderator
Staff member
Thanks to both for answering. Let me see if and what I understood.

Systems Adict, I have very little clue on what the point you're trying to make is, though I do understand what you're saying. What exaclyl would we lose if we used C4?
Systems Adict is saying we have better explosives than C4 and these are used in artillery shells. IMHO, the way explosives work can be tailored for different explosive effects and hence silly to use C4 in this application.
 

Todjaeger

Potstirrer
Systems Adict is saying we have better explosives than C4 and these are used in artillery shells. IMHO, the way explosives work can be tailored for different explosive effects and hence silly to use C4 in this application.
Pretty much. Another way to potentially look at it is to consider the range of hydrocarbon fuels, along with their different properties and then consider why certain fuels are used in some applications but not others.

Coal for instance is readily available and used in electricity generation as well as heating. However, it would not make a particularly useful fuel to power an aircraft...

The fuel JP-8 which is widely used in both aircraft and ground vehicles within the US armed forces could likely also be used for electrical generation and heating, however the energy requirements involved in refining petroleum into JP-8 would likely make regular use of JP-8 for electricity and heat unlikely, as there are more cost effective fuels available.
 

Rob c

The Bunker Group
Verified Defense Pro
The first requirements of any explosive used in gun ammunition is that it is stable enough to withstand the forces generated when firing the gun and that it remains stable for a significant period of time in storage. The period of time can be decades like when the U.S.N. recommissioned its battle ships in the 1980's and used them in the 1990's to fire at targets they were using shells produced during WW2. While a significant number of explosives are considered stable, they are not stable enough to be fired from a gun. for instance the common explosives gelignite and dynamite can take a lot of abuse but will detonate if used in a gun as the forces involved are very high.
 
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