AP vs HE - Short barrel vs Long

[:USERNAME:]

Ponderous

Lets start with physics and work our way out from there.

Kinetic energy has alot to do with energy. Momentum does not relate to energy. One is a scalar and one is a vector.

Anyone a mech engineer care to confirm, deny, add to this?

Lewis

[Rattus]

Unless I went to really bad school (possible)

Kinetic Energy = 1/2 mass * velocity squared.

Momentum = mass * velocity.

Velocity is common term so yes related.

Bed time now!

[:USERNAME:]

LOL!!!!

They both have equal signs too...

[Rattus]

Damn! - the equals sign - If i'd realised that I could have done without the other terms!

[dNorwood]

<BLOCKQUOTE>quote:</font><HR>Originally posted by :USERNAME::

Lets start with physics and work our way out from there.

<HR></BLOCKQUOTE>

[sigh] I really tried to stay out.

<BLOCKQUOTE>quote:</font><HR>

Kinetic energy has alot to do with energy. Momentum does not relate to energy. One is a scalar and one is a vector.

Lewis<HR></BLOCKQUOTE>

Apropos of nothing:

Kinetic energy is indeed a scalar (and by definition the other form of energy).

Momentum is definitely a vector - if I form the dot product of momentum with itself (thus getting the squared magnitude of this vector) and divide by twice the mass, I get kinetic energy. Momentum relates DIRECTLY to kinetic energy.

You may trust me that it is a DESPERATELY long way from these simple definitions to an answer to the current debate. It really is best to find out what is EMPIRICALLY true rather than trying to baffle people with...well, you know.

[Philistine]

Re: looking at this from a physics point of view. (Bear in mind I have no actual military service nor do I have any practical physics training other than a year and a half of college as a physics major before I decided that the humanaties were for me...So take this for what it's worth).

My calculation of the energy content of a kilogram of HE (TNT) is 4.2E6 Joules. (I get this by using the constant bandied about for the energy content of a megaton of TNT being 4.2E15 Joules and assume that 1 megaton=1E9 KG--not sure if megaton is metric ton or short ton or long ton, but I'm using metric tons b/c the math works much better )

.853 KG Amatol I'm going to assume = 1KG TNT (partly because I understand it was more explosive than TNT, but primariliy, because it makes the math easier [do you see a trend]).

Now, you had said that a 75mm German HE shell has a velocity of 550 m/s, which gives a KE of 3.025E5 Joules per Kilogram. Any idea of the the weight of the shell? (The weights given by Rattus seem to be on the order of 7 KG for shell, propellent & casing). Say, 4 KG for shell? (say it with me: "It makes the math easier")--for aprox. 1.2E6 Joules.

Which is approx. 35% of the energy provided by the HE payload.

Of course, a couple of caveat's -- HE (unless it is HEAT or similar) explodes in 360 degrees and the KE of the shell is only 1.2E6 J at the muzzle, it would fall of fairly rapidly with range.

Given all this, it seems that although the KE of the shell provides a significant portion of the KE, the major portion is provided by the HE (which seems reasonable, otherwise, why not just use solid shot at high velocity?)

Just playing with numbers here--the broadest back of the envelope things. I haven't checked this, or even really thought it out all that well, but that seems to be a trait hereabouts...

--Philistine

[Guest Mirage2k]

This may be an oversimplification, but...

I always assumed that a HE shell exploded at pretty much the same time of the impact, that is, a HEAT round detonates when it strikes (hopefully) the armor of the target. If the round detonates in that fashion, what is the point of having a high velocity, other than for reasons of accuracy? What I mean is, a lot of that energy is going to be wasted when the round detonates, right? An AP round such as a Sabot actually uses its kinetic energy to pierce the target's armor, throwing debris around inside. It doesn't explode, so it needs to get all of its destructive power from its initial velocity. The same is not true for an HE round, which gets most of its destructive power from the HE.

That's just the way I've always assumed it works. I'm sure someone will correct me.

-Andrew

------------------

Throw me a frickin' smiley, people!

Your one-stop-shop for gaming news is www.SiegersPost.com ! Hit it!

[Rattus]

Weight of projectile for most 3" projectiles is about 7kg. Bursters (fillers)forming 0% (for monobloc AP shot) to 10% (for HE High capacity). Suffice to say that against face hardened armour plate at high velocities at which an HE round might otherwise be expected to perform as an increased capacity APHE round, the deformation of the HE shell nose and damage to the fuse will probably result in either partial or no detonation and because of loss of projectile weight and nose deformation, greatly reduced penetration. The greater the burster charge the greater the cavity=weaker shell the worse the problem. At close range and extremely high velocities it really does matter what you fire - even a non-detonating nose shattered round will penetrate some/some armour - but no where near as much as an intact round.

Maybe I post something on armour piercing caps and decapping?

[:USERNAME:]

<BLOCKQUOTE>quote:</font><HR>Originally posted by dNorwood:

Apropos of nothing:

Kinetic energy is indeed a scalar (and by definition the other form of energy).

Momentum is definitely a vector - if I form the dot product of momentum with itself (thus getting the squared magnitude of this vector) and divide by twice the mass, I get kinetic energy. Momentum relates DIRECTLY to kinetic energy.

<HR></BLOCKQUOTE>

Perhaps you can enlighten us as to why you are doing the math you are doing.

MV.MV cos0? (dot product)

This is MMVV

Why are you dividing by 2M then? Other than you want to get to 1/MV^2, what physics are you doing? What principle?

Are you really a Physics prof? Where do you teach?

Lewis

PS I am very disappointed that people here arent applying Calculus and noticing that KE is the integral of Momentum.

[This message has been edited by :USERNAME: (edited 08-04-2000).]

[Guest Pillar]

This is a really interesting discussion.

Let's try to keep it intellectual and avoid the snappy tongues and sarcasm.

C'mon, it can't be that hard

Pursue Truth!

[Jeff Heidman]

The funniest thing about this math discussion is that it is irrelevant.

Leroy, lets, for the sake of argument, say you are totally correct. I was completely wrong when I ever even mentioned momentum. I was grossly in error, and should probably be shot for making such a travesty of modern physics.

So what? It has no bearing on the argument, which you have rather soundly lost. So why keep bringing it up? Can you say "Red Herring"? i knew you could! <insert smiley here, except I can't be bothered to figure out how to insert them>

Jeff

[:USERNAME:]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Jeff Heidman:

The funniest thing about this math discussion is that it is irrelevant.

Jeff<HR></BLOCKQUOTE>

Just a hint. We are talking about physics not math. The funny thing is that you dont know that.

I think if you would bring into your discussion some facts or scientific principles then you wouldnt be irrelevant. TOW gunners have high GT scores?

Lewis

[Guest *Captain Foobar*]

Lewis, do you enjoy this kind of discourse?

[Jeff Heidman]

<BLOCKQUOTE>quote:</font><HR>Originally posted by :USERNAME::

Just a hint. We are talking about physics not math. The funny thing is that you dont know that.

<HR></BLOCKQUOTE>

No, the funny thing is that apparently you do not realize how stupid you look when you attack people on trvialities because you cannot touch them on substance.

"Physics, not math" indeed. You are really grasping at straws. Now you are telling us that KE=1/2mv^2 is not math. And, since you brought it up yourself, apparently calculus is not math either.

Jeff

[:USERNAME:]

Jeffy

The whole discussion/debate/disagreement hinges on physical principles. Physics is resolved with mathematical formulae that agree with those principles. I cant have math for maths sake. You either get it or you dont. You are getting surly and disagreeable.

Lewis

[:USERNAME:]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Philistine:

Re: looking at this from a physics point of view. (Bear in mind I have no actual military service nor do I have any practical physics training other than a year and a half of college as a physics major before I decided that the humanaties were for me...So take this for what it's worth).

My calculation of the energy content of a kilogram of HE (TNT) is 4.2E6 Joules. (I get this by using the constant bandied about for the energy content of a megaton of TNT being 4.2E15 Joules and assume that 1 megaton=1E9 KG--not sure if megaton is metric ton or short ton or long ton, but I'm using metric tons b/c the math works much better )

.853 KG Amatol I'm going to assume = 1KG TNT (partly because I understand it was more explosive than TNT, but primariliy, because it makes the math easier [do you see a trend]).

Now, you had said that a 75mm German HE shell has a velocity of 550 m/s, which gives a KE of 3.025E5 Joules per Kilogram. Any idea of the the weight of the shell? (The weights given by Rattus seem to be on the order of 7 KG for shell, propellent & casing). Say, 4 KG for shell? (say it with me: "It makes the math easier")--for aprox. 1.2E6 Joules.

Which is approx. 35% of the energy provided by the HE payload.

Of course, a couple of caveat's -- HE (unless it is HEAT or similar) explodes in 360 degrees and the KE of the shell is only 1.2E6 J at the muzzle, it would fall of fairly rapidly with range.

Given all this, it seems that although the KE of the shell provides a significant portion of the KE, the major portion is provided by the HE (which seems reasonable, otherwise, why not just use solid shot at high velocity?)

Just playing with numbers here--the broadest back of the envelope things. I haven't checked this, or even really thought it out all that well, but that seems to be a trait hereabouts...

--Philistine

<HR></BLOCKQUOTE>

Phil

I dont want your post to go unrecognized. A very worthy effort and when I get time, plan on going through the numbers.

I never said that Kinetic Energy WAS the main contribution but a contributing factor along with much greater accuracy and the chance to quickly view the results of a shot before correcting for the next one. A multivariable force multiplier and therefore non-intuitive to rocket launcher types.

As for the people that believe that it doesnt matter if you tie a shell to a monkeys back and have him climb onto a bunker and command detonate it or have the shell traveling at Mach 20 'cause 'sploshuns iz just 'splosions...well, good luck.

Nice job.

Lewis

[Guest Pillar]

I've got an idea that will solve both problems.

Have a dispensible drag chute or drag fans that come out of the shell at the last few seconds to slow it down just before impact.

Problem solved.

[Guest Mirage2k]

<BLOCKQUOTE>quote:</font><HR>Originally posted by :Username::

As for the people that believe that it doesnt matter if you tie a shell to a monkeys back and have him climb onto a bunker and command detonate it or have the shell traveling at Mach 20 'cause 'sploshuns iz just 'splosions...well, good luck.<HR></BLOCKQUOTE>

Um...I don't think anyone said anything like that

Really though, Lewis, even though I'm kinda just waltzing in here and probably shouldn't be posting, I'm having trouble following your argument. One of your earlier posts said something to the effect of (paraphrasing) "since velocity is squared to find the kinetic energy, the energy imparted by an HE round on a target is based on its velocity."

But doesn't the HE round explode very soon after it hits the target? Isn't most of this energy lost anyway? It seems like your argument is more applicable to AP rounds.

-Andrew

------------------

Throw me a frickin' smiley, people!

Your one-stop-shop for gaming news is www.SiegersPost.com ! Hit it!

[Jeff Heidman]

<BLOCKQUOTE>quote:</font><HR>Originally posted by :USERNAME::

Jeffy

You are getting surly and disagreeable.

Lewis<HR></BLOCKQUOTE>

My irony meter just broke.

Anyway, on the advice of multiple people who have seen fit to email me and tell me that discussing anything with you is a waste of time, I shall remove myself from this rather lame attempt at a real discussion. Lewis, you are a piece of work, to say the least. Have a nice life, troll.

Jeff Heidman

[Guest Mirage2k]

<BLOCKQUOTE>quote:</font><HR>Originally posted by :USERNAME::

Theres a big difference between indirect and direct fire HE. Normally a direct fire HE weapon is attacking a hardened target. Either a bunker, trench, stone building, etc. Schrapnel is not the agent of destruction as much as the explosion itself.<HR></BLOCKQUOTE>

If you agree that shrapnel is not the primary agent of destruction of an HE round against a hardened target in a "direct fire" situation, why is it so important for the HE to be traveling at a high velocity? An AP round, such as the Sabot, uses its high velocity to create shrapnel. An HE round uses its explosive power, which is not dependent on its velocity.

-Andrew

------------------

Throw me a frickin' smiley, people!

Your one-stop-shop for gaming news is www.SiegersPost.com ! Hit it!

[:USERNAME:]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Pillar:

I've got an idea that will solve both problems.

Have a dispensible drag chute or drag fans that come out of the shell at the last few seconds to slow it down just before impact.

Problem solved. <HR></BLOCKQUOTE>

LOL

They have them. Its called Retarded bombs (they have smart bombs so why not retarded bombs). VERY Apropo here.

I am glad rocket boy jeffy has decided to drop out. He really was floundering like a fish out of water in a technical conversation and has justified quitting in his mind. People have emailed me that perhaps his talents run better towards testing the game as is and gathering data like a squirrel gathers nuts. I, myself, like to question "why are there nuts" and why filberts are so often over represented in mixed nuts scenarios.

As for anyone else (especially alledged physiks prophezzors), I am still here , standing up and sticking to my guns, waiting for all comers.

Lewis

[:USERNAME:]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Mirage2k:

But doesn't the HE round explode very soon after it hits the target? Isn't most of this energy lost anyway? It seems like your argument is more applicable to AP rounds.

-Andrew

<HR></BLOCKQUOTE>

No energy is ever lost in my world. If you check the lost and found it'll be there.

Collisions are elastic or non elastic with the difference being in energy (and momentum..hahahah) being imparted on the target. In the case of lets say AP hitting a brick house, There is very little energy transferred. A couple of bricks are knocked into red dust and some are thrown clear from fracture, but the AP shell has not been "decellerated" and transferred its energy. In the case of HE, where the shell itself blows apart into hot gas and small pieces, the energy IS transferred. You can literally think of the explosion as "moving" forward with extra "force".

Its obvious that BTS did factor this in for HE rounds against ARMOR so I am glad. As far as HE against other targets it should be factored into the "blast" abstraction.

Lewis

[PzKpfw 1]

<BLOCKQUOTE>quote:</font><HR>Originally posted by :USERNAME::

I am glad rocket boy jeffy has decided to drop out. He really was floundering like a fish out of water in a technical conversation and has justified quitting in his mind. People have emailed me that perhaps his talents run better towards testing the game as is and gathering data like a squirrel gathers nuts. I, myself, like to question "why are there nuts" and why filberts are so often over represented in mixed nuts scenarios.

<HR></BLOCKQUOTE>

Heh, couldn't resist getting that last word in eh Lew. Why wouldn't he go, you can't get blood from a stone , some people are never wrong right Lew.

<BLOCKQUOTE>quote:</font><HR>

As for anyone else (especially alledged physiks prophezzors), I am still here , standing up and sticking to my guns, waiting for all comers.

Lewis<HR></BLOCKQUOTE>

I'm sure thats a big comfort to everyone , here and at the same time ponder how long before this thread is locked, as its hard to carry out a 1 sided conversation.

Regards, John Waters

[This message has been edited by PzKpfw 1 (edited 08-05-2000).]

[:USERNAME:]

<BLOCKQUOTE>quote:</font><HR>Originally posted by PzKpfw 1:

I'm sure thats a big comfort to everyone , here and at the same time ponder how long before this thread is locked, as its hard to carry out a 1 sided conversation.

Regards, John Waters

[This message has been edited by PzKpfw 1 (edited 08-05-2000).]<HR></BLOCKQUOTE>

Aside from all your self-amused snide comments, What are you saying?

Other people here are interested, some enough to make a concerted effort at applying engineering principles. I think the game already applys some of the principles that are being discussed. Just because someone has to flit off in a huff doesnt mean that the thread has to be locked. The conversation is one sided how (carry out?)? Because I am man enough to defend my technical know-how? Because someone else gets his opinions about me from other people? He can call me a troll and then run up a tree like a squirrel. Thats fine by me.

Yeah Regards

Lewis

"Heh, couldn't resist getting that last word in eh Lew. Why wouldn't he go, you can't get blood from a stone , some people are never wrong right Lew."

PS I am not right, my facts, engineering, physical principles, mathematics ARE right. "Eh" yourself. In retrospect maybe you should have resisted.

[This message has been edited by :USERNAME: (edited 08-05-2000).]

[PzKpfw 1]

<BLOCKQUOTE>quote:</font><HR>Originally posted by :USERNAME::

Aside from all your self-amused snide comments, What are you saying?

<HR></BLOCKQUOTE>

Your the man with all the answers Lewis, figure it out.

<BLOCKQUOTE>quote:</font><HR>

Other people here are interested, some enough to make a concerted effort at applying engineering principles. I think the game already applys some of the principles that are being discussed. Just because someone has to flit off in a huff doesnt mean that the thread has to be locked. The conversation is one sided how (carry out?)? Because I am man enough to defend my technical know-how? Because someone else gets his opinions about me from other people? He can call me a troll and then run up a tree like a squirrel. Thats fine by me.

Yeah Regards

Lewis

<HR></BLOCKQUOTE>

Are they Lewis?, they may have been before, their was a good discussion going, but your overbearing attitude pretty much killed that.

Had you adressed their counterpoints instead of takeing every point that disagreed with you as an attack an great thread might have developed.

You accuse me of being 'snide' yet fail to recognize that your posts are full of what many here see as snideness, thats akin to the pot calling the kettle black.

I have lurked here for a while & seen the same results whewnever you decide to champion your opinion in an thread it dies. Why should ppl continue to discuss it with you? they leave you take the opertunity to belittle them & claim it as more evidence you were right etc, instead of seeing it for what it is, you sticking to your guns is an a great thing as long as you also can lower your sheilds long enough to see that other ppl can also be right & commended as well for sticking to their guns, w/o the need for personel or snide remarks, and tha ability to recognize you get what you give eventualy.

<BLOCKQUOTE>quote:</font><HR>

PS I am not right, my facts, engineering, physical principles, mathematics ARE right. "Eh" yourself. In retrospect maybe you should have resisted.<HR></BLOCKQUOTE>

Your reply garnered the exact response I knew it would Lewis, especialy your retrospective comment .

Are they Lewis, I'll forward your remarks to a few freinds see if they agree. But I'm still waiting for you to adress the counter points raised by Jeff Heidman & the other posters, that disagreed with your thesis, and were ignored or treated to snide remarks, while conviently skirting the issue.

With that in mind I'd realy like to see that reply to the physics Prof post that you said, if you had time to someday you would respond to his points. Lets see that and the rebuttal and go from their if anyone bothers to contribute to this thread anymore .

Regards, John Waters