Medium caliber HE blast values in CMBB

[Mr. Tittles]

The 50mm HE sprg could be fired from PAK 38, and KWK 50mm weapons. I believe the L60 KWK and L60 PAK shared ammo (but there may have been a difference in firing technology; electric vs percussion). The 50mm 'short' had a different necked-down case but probably shared projectiles with the longer version.

The Germans made 2,426,300 50mm HE rounds in 1942. Thats the majority type for this year for this caliber. It must been the majority type fired also.

Much ammo is destroyed by artillery, air attack, weather, abandonment, etc. But the production numbers do give a relative usage level.

It certainly was a big AP40 user (check out the production number for 37mm AP40, its certainly a common round). Wonder how much was available once production stopped? Pumas perhaps getting some? The 50mm ammunition production shows this weapon family to have been a major player in 1939-1944.

A point about ATGs firing HE. If the HE round is fired at a lower velocity, the weapon should be very stable and repeatable.

http://members.tripod.com/~Sturmvogel/GermWeapProd.html

[ November 09, 2003, 11:44 AM: Message edited by: Mr. Tittles ]

[Mr. Tittles]

I think weapons should have multi-ratings as follows:

1. Blast: reflection of the weapons explosive destructiveness. Its ability to knock down buildings, bunkers, tracks off tanks, etc. Mostly based on HE content but also influenced by velocity and mass of the incoming projectile. Blast is also tied to dust effects from ground-target conditions.

2. Fragmentation: Reflection of the deadly projectile emission. Based on a standard. Mortar standard is 85 degree angle of attack. Indirect based on 45 degree angle, direct fire based on 4 degree. All on flat open ground firm soil point detonatation. Reflects an area in square dimensions that 50% casualty fragmentation produces. Shape mentioned (circular, elipse, clover, etc. Fragmentation has a dust creating component also but smaller than blast.

3. Incindiery. Reflects ability of projectile to start fires. (parentheses shows seconds duration) Also a flame effect that may cause casualties/troop displacement.

4. Fuze options. Point detonating/Delay/Time. Direct fire: point detonating may cause airburst in woods and other vertical targets. Delay may cause internal building airbursts and airbursts in open terrain (ricochet).

Indirect fire: Point detonating may also cause airbursts in woods/trees/etc. Delay may cause superior destruction of trenches, buildings or, if the angle of descent is steep enough, a ricochet effect.

Some examples would be:

50mm mortar

blast: 6

frag: 78.5/circ

incindiery: 2 (1)

fuze: point

50mm ATG L/60

blast: 14

frag: 61.5/fwd V

incidiery: 3 (1)

fuze: point/delay

60mm mortar WP

blast: 1

frag: 8/circ

incidiery: 20 (50)

fuze: point/delay

105mm HE

Blast: 114

frag: 4800/clover

incidiery: 4 (2)

fuse: point/delay/time

These are just made up guesses but the idea is to break out the weapons characteristics. There is still much more going on behind the scenes due to flatness of terrain, target type and cover, etc. Actual angles would shape patterns differently.

[ November 09, 2003, 07:37 PM: Message edited by: Mr. Tittles ]

[Michael Emrys]

Originally posted by redwolf:

Another interesting number is the number in 41. I don't know out of my head how many 50mm Pz IIIs they had, but 330,000 for six months is a lot of ammo for so few tanks.

I can't rattle off numbers, but I thought that all the Pz IIIs, except for one regiment, had converted to 50mm armed.

Michael

[Mr. Tittles]

Vf=D/3 (sqrt(2M/(2m+M)))

where D is explosives detonation velocity M/s

M is mass of explosive in kg

m is mass of case

This lovely equation is brought to you by The Royal Order of Cannonballers

http://www.atra.mod.uk/RSABST/HTML/WarHeadsIndex.HTML

Smashing stuff. Got to love them British. i recommend anyone that cares about HE read this.

Basically a formula for Fragment velocity (Vf)

I will develop some interesting applications in following posts. Basically the following will be shown:

1. When a bomb/shell drops on its nose vertically, it better have either a very slow descent or a very fast explosive (read: explosive train). Mortars do this very well.

2. When a direct fire weapon, like a tank gun fires a HE shell, it is actually advantagous (in certain circumstances) to have a high velocity projectile/low explosive content.

3. The fuze anddd the angle are such major players that to not include them will ignore major weapons differences.

One thing I hope everyone can get from this thread; the thought that the projectiles velocity has no impact on the outcome of the HE event is rubbish. Many people just look at HE content and wall thickness. They have to take into account these factors as well as projectile velocity, angle of attack, fuze options, etc.

[ November 11, 2003, 11:47 PM: Message edited by: Mr. Tittles ]

[Mr. Tittles]

TNT

D=24,400 fps (7507 M/s)

M48,75mm high-explosive shell,standard (for M3

and M4)

;shell contained 1.47

lbs.of TNT (or 0.11 lbs.of cast TNT and 1.36 lbs.of

Amatol as an alternate);

{TNT is 0.668 kg)

81mm mortar

Firing;mortars .Ammunition

was an H.E.shell,M43A1 (6.87 lbs.)(range 100 to

3290 yds.);

M43A1 —81mm,H.E.shell,6.92 lbs.,TNT bursting

charge of 1.22 lbs.or 0.98 pound of 50/50 Amatol

and 0.19 pound cast TNT,or 1.28 pounds trimonite

(Drawing in 1944 Catalogue,p.529).

American shell 75mm M3 shell HE M48

Total wt (lbs) 14.6 (6.636 kg)

Filling (lbs) 1.7 ?

So..

D=7507

M=0.668

m=6.636-0.668=5.96

Vf=7507/3[sqrt(2*0.668)/(2*5.96+0.668)]

Vf=2859 M/s

This is the initial static velocity given to a 75mm M48 HE shell fragments. The forward velocity from the gun is around 570 M/s. The HE shell is spinning and the fragments from the sides of the shell would get another 75 M/s or so.

Refering to the link above, the vector angle from the dynamic forward component of the shells velocity gives:

v=sqrt((2859+75)^2+ (570)^2)= 2989 M/s

angle =79 degrees (measured from 0 degrees being along the flight of the shell)

In the case of a HE filled shell, like the sherman 75mm M48, it can be characterized as having a HE content that will throw the majority of its steel fragments at a substantial angle. That is, it will blast most metal out sideways. The forward velocity, even using a muzzle velocity, does not 'tilt forward' the fragment spray appreciably. The static Vf is 5 times greater than the muzzle velocity.

(to be continued)

[ November 11, 2003, 07:14 PM: Message edited by: Mr. Tittles ]

[JasonC]

Whaddya know, I'm away from this thread for a few days and all of this. Where to begin.

First with TNT vs. amatol. Usefulness as a cutting charge has nothing to do with explosive effect, and one factor does not describe all uses of explosives. Amatol is made by mixing TNT, a true high explosive, with ammonium nitrate (AN), a much slower, "push" explosive, that happens to have a very high gas volume (980 cubic cm per gram, vs. 710 for TNT). This can be useful for moving rock or cutting a beam, but for shrapnel production what you want is high detonation velocity and high total energy of detonation.

The det velocity of TNT is 6940 meters per second. For AN it is only 2700 m/s. For 80/20 amatol it is 5200 m/s. Total detonation energy is 4.23 megajoules per kg for TNT, 2.63 for AN, and 4.1 for 80/20 amatol. The point of amatol as a burster is to get most of the total energy of TNT, and most but not all of its det velocity, for less nitrate "invested".

For shrapnel production the most relevant item is the square root of the det velocity. Which means TNT with 6940 vs. 80/20 amatol with 5200 is about 1.155 times as effective, or .87 times TNT for the 80/20.

Note also that these detonation velocities are an order of magnitude larger than shell velocities. The shell is almost standing still compared to the explosion. Yes there is plenty of kinetic energy in the smaller rounds, around the same order of magnitude as the explosive charge (a few millions of joules). But most of it stays in slow moving large hunks.

Shrapnel effectiveness comes from coverage, which comes from the little stuff, which is made by the explosive. More explosive and more powerful explosive means a larger number of smaller fragments and more complete coverage of the CZ area as a result. That is why det V is the main thing.

On 105s, at the muzzle no doubt, I was referring to personal experience that you can in fact hear them when they are coming in, or are shot overhead. They are definitely subsonic by then, at typical artillery ranges (several miles). (You can also see them if you are looking the right way, no surprise).

On supposed effectiveness of 50mm or 45mm HE, the basic problem is that the bursting charge is well under one pound. If you get a nearly direct hit that is no doubt still enough to ruin your whole day. But it is half what there is in a 75mm, 76mm, or 81mm mortar shell, and more like 1/6 what there is in a real artillery shell like a US 105.

One German use of 50s, the figures you have are for HE production for the ATGs. I do not think it includes tank HE at all. There were 2500 50mm AFVs by 1941, and I doubt very much that 600k shells were enough for all of them, on top of the towed 50s. The shape of the ammo curve makes perfect sense, on the other hand, for the towed 50s. It jumps into the millions as those are deployed in numbers in 1942, peaks with the number of 50s fielded, and declines rapidly about a year after the production of the guns themselves.

The Germans fielded almost 10k 50mm PAK. There were 2K made by the end of 1941 but much of that was probably accumulated in the rear and given to units forming, only changing in that respect late in the year. Thus the low ammo made through the end of 1941. In 1942 there are thousands more guns made and it becomes the standard type in all the Pz Jgr units. Some are undoubtedly lost in action, with a gun's half-life probably something on the order of 6 months or so.

In 1943 they were still being made for the first part of the year, though the 75mm PAK was starting to replace them. Ammo use continues high because they are in the field in large numbers, still. 1943 production probably covered losses in action for the first half of the year or so, but after that the number left alive certainly declined. In the course of 1944 the number in the field probably went from something like half the peak value down to an eighth.

If you look at the number of rounds per gun made, it comes to 770. That is typical of direct fire guns. Compare the ammo made for 105s, which comes to 5750 rounds per gun. If the direct fire figure seems high, realize that it amounts to a ration of about 2 rounds per gun per day, if the half life is 6 months. That is not a lot of firing. The counter-intuitive bit is just that guns live for long periods of time, instead of "use 'em and they die".

On hyper realistic HE modeling, I don't think it adds much at all, frankly. Consider circular bursts from mortars vs. distorted cones with larger lobes forward for 45 degree impact FO arty. Since the point of impact has been selected randomly to start with, how much difference does this make? If you take the lobe shape's center of mass and place it randomly, you get very close to the same effect.

So the crater is in a slightly different location, by 5m or whatever. Who cares? Your chance of being in the lethal zone is not a function of the spatial relation of impact point and blast lobes, it is merely a matter of the ratio of overall CZ area and scatter width - since shell placement is randomized already. If you got hyper detailed about lobe shapes, people would just put their aim point 20m in front of where they do now.

With flat trajectory fire there might be more of a difference. But the error is all along the range axis in direct fire, anyway. The side lobes are larger in a circular model than they are in real life. But guns don't miss to the side. Perhaps it makes such fire slightly more effective against "overstacked" cover than it actually would be, but as a minor thing in rare cases.

The real difference would be in shot effect when the range is long. Right now that can still happen and effect the target if the shot is close enough. In reality, more of the blast would vector forward somewhat, making marginal longs pretty ineffective. On the flip side, shorts that aren't quite as close might still do something.

This isn't a symmetric situation as it is with the FO case above, because range high near errors are much more common than "range short by 50-60m" cases. (You don't just move the aim point, because your only target reference is the object aimed at). So direct fire HE might be marginally less effective than circular bursts model it.

I think they are already less effective than in reality, however, because target height is really only modeled for buildings. You can hit a gun on the fly in real life - that doesn't happen in CM. It is probably a wash.

As for why Russian 120s are given slightly higher blast than Germans, it may well be correct even though they are the same weapons. The HE filler is probably not the same, as the Germans faced greater explosives shortages than the Russians did (thanks in great measure to lend lease, incidentally. The Russians lost a lot of ammo production capacity in the Ukraine).

What isn't probably a wash is high content, high quality explosive shells having the same blast ratings as low content and lower quality explosive ones. The leading example in CMBO was the 4.5 inch, which in reality had no more filler than a US 105, but was given 5/3rds the blast rating in CMBO. Very closely tracking shell weight.

[Mr. Tittles]

Originally posted by JasonC:

Whaddya know, I'm away from this thread for a few days and all of this. Where to begin.

.

Well you could begin by admitting you were wrong about the 105mm shell being heard or not. Its obvious you did not read the whole link that described the high velocity shot. Andreas caught you on that and so did I. If you are to be taken seriously, then please read the links, etc.

[ November 11, 2003, 10:04 PM: Message edited by: Mr. Tittles ]

[Mr. Tittles]

DETONATION

Substances which content themselves with merely

exploding, we group together as ‘low’ explosives;

(This term “low” was dropped in favour of the word

“Propellant” Substances which undergo “Detonation”

have undergone a further step in the field of chemical

decomposition. The term “Detonate” derives from the

Latin ‘be’ (down) and ‘tonare’ (to thunder) Substances

that detonate are called “High Explosive”(HE),

Indicating that their behaviour pattern has become

enhanced in some way. Usually, a high explosive starts

to burn when initiated, but the action accelerates rapidly

to a point where the pattern changes to a sudden

wave of molecular disturbance which is propagated

throughout the explosive substance (Fig 9) and is

known as the ‘detonation wave’. See Fig 2 for a definition

of the word “Detonate”

BRISANCE

The intense crushing, shattering effect (called

“Brisance”) (The adjective form of this word is

“brisant” ) which a detonating explosive can exert on

hard materials is due to the shock wave. The Brisance

of an explosive is a qualitative description of how much

damage it will do when exploded. It is a function of the

“Velocity of Detonation” and the pressure exerted by the

shock wave, know as “Detonation Pressure” The word

Brisant originates from the French verb, Briser, which

means “To break” in English. Brisance does not have

any scientific units and cannot be calculated.

DETONATION VELOCITY AND PRESSURE

The detonation velocity is defined as the velocity of

sound in the explosive at the temperature it detonates

at, added to the speed of the reacting material as

it moves forward in the detonation wave.

Example

Sound travels at 5400 ms-1 in detonating TNT. The

speed of the reacting TNT as it moves forward in the

detonation wave is 1500 ms-1

Answer

The Detonation Velocity of TNT is 5400 + 1500 = 6900

ms-1

The Detonation Pressure (P) can be calculated from the

formula below

P = 2.5 x ∆ x D2 ÷ 1000 000 where:

∆ = Density of HE in gcm–3

D = Detonation velocity in ms–1

The units of Detonation pressure are kBar

Example

Given that the density of TNT is 1.57 gcm–-3 find the

Detonation pressure.

Answer

P = 2.5 x 1.57 x 69002 ÷ 1000 000

P = 187 kBar

To get some idea of the size of this pressure here are

three facts about 187 kBar

• It is 187 000 x Atmospheric Pressure

• It is 1000 x the pressure that liquid hydrogen must

be stored at in order to keep it a liquid.

• If a 40 Tonne Lorry was dropped on to a needle that

has a square cross section 1.5mm x 1.5mm, the

pressure at the other end of the needle would be 187

kBar.

[Mr. Tittles]

Are you refering to detonation pressure?

[Mr. Tittles]

Originally posted by JasonC:

Whaddya know, I'm away from this thread for a few days and all of this. Where to begin.

First with TNT vs. amatol. Usefulness as a cutting charge has nothing to do with explosive effect, and one factor does not describe all uses of explosives. Amatol is made by mixing TNT, a true high explosive, with ammonium nitrate (AN), a much slower, "push" explosive, that happens to have a very high gas volume (980 cubic cm per gram, vs. 710 for TNT). This can be useful for moving rock or cutting a beam, but for shrapnel production what you want is high detonation velocity and high total energy of detonation.

The det velocity of TNT is 6940 meters per second. For AN it is only 2700 m/s. For 80/20 amatol it is 5200 m/s. Total detonation energy is 4.23 megajoules per kg for TNT, 2.63 for AN, and 4.1 for 80/20 amatol. The point of amatol as a burster is to get most of the total energy of TNT, and most but not all of its det velocity, for less nitrate "invested".

For shrapnel production the most relevant item is the square root of the det velocity. Which means TNT with 6940 vs. 80/20 amatol with 5200 is about 1.155 times as effective, or .87 times TNT for the 80/20.

Note also that these detonation velocities are an order of magnitude larger than shell velocities. The shell is almost standing still compared to the explosion. Yes there is plenty of kinetic energy in the smaller rounds, around the same order of magnitude as the explosive charge (a few millions of joules). But most of it stays in slow moving large hunks.

Shrapnel effectiveness comes from coverage, which comes from the little stuff, which is made by the explosive. More explosive and more powerful explosive means a larger number of smaller fragments and more complete coverage of the CZ area as a result. That is why det V is the main thing.

On 105s, at the muzzle no doubt, I was referring to personal experience that you can in fact hear them when they are coming in, or are shot overhead. They are definitely subsonic by then, at typical artillery ranges (several miles). (You can also see them if you are looking the right way, no surprise).

On supposed effectiveness of 50mm or 45mm HE, the basic problem is that the bursting charge is well under one pound. If you get a nearly direct hit that is no doubt still enough to ruin your whole day. But it is half what there is in a 75mm, 76mm, or 81mm mortar shell, and more like 1/6 what there is in a real artillery shell like a US 105.

One German use of 50s, the figures you have are for HE production for the ATGs. I do not think it includes tank HE at all. There were 2500 50mm AFVs by 1941, and I doubt very much that 600k shells were enough for all of them, on top of the towed 50s. The shape of the ammo curve makes perfect sense, on the other hand, for the towed 50s. It jumps into the millions as those are deployed in numbers in 1942, peaks with the number of 50s fielded, and declines rapidly about a year after the production of the guns themselves.

The Germans fielded almost 10k 50mm PAK. There were 2K made by the end of 1941 but much of that was probably accumulated in the rear and given to units forming, only changing in that respect late in the year. Thus the low ammo made through the end of 1941. In 1942 there are thousands more guns made and it becomes the standard type in all the Pz Jgr units. Some are undoubtedly lost in action, with a gun's half-life probably something on the order of 6 months or so.

In 1943 they were still being made for the first part of the year, though the 75mm PAK was starting to replace them. Ammo use continues high because they are in the field in large numbers, still. 1943 production probably covered losses in action for the first half of the year or so, but after that the number left alive certainly declined. In the course of 1944 the number in the field probably went from something like half the peak value down to an eighth.

If you look at the number of rounds per gun made, it comes to 770. That is typical of direct fire guns. Compare the ammo made for 105s, which comes to 5750 rounds per gun. If the direct fire figure seems high, realize that it amounts to a ration of about 2 rounds per gun per day, if the half life is 6 months. That is not a lot of firing. The counter-intuitive bit is just that guns live for long periods of time, instead of "use 'em and they die".

On hyper realistic HE modeling, I don't think it adds much at all, frankly. Consider circular bursts from mortars vs. distorted cones with larger lobes forward for 45 degree impact FO arty. Since the point of impact has been selected randomly to start with, how much difference does this make? If you take the lobe shape's center of mass and place it randomly, you get very close to the same effect.

So the crater is in a slightly different location, by 5m or whatever. Who cares? Your chance of being in the lethal zone is not a function of the spatial relation of impact point and blast lobes, it is merely a matter of the ratio of overall CZ area and scatter width - since shell placement is randomized already. If you got hyper detailed about lobe shapes, people would just put their aim point 20m in front of where they do now.

With flat trajectory fire there might be more of a difference. But the error is all along the range axis in direct fire, anyway. The side lobes are larger in a circular model than they are in real life. But guns don't miss to the side. Perhaps it makes such fire slightly more effective against "overstacked" cover than it actually would be, but as a minor thing in rare cases.

The real difference would be in shot effect when the range is long. Right now that can still happen and effect the target if the shot is close enough. In reality, more of the blast would vector forward somewhat, making marginal longs pretty ineffective. On the flip side, shorts that aren't quite as close might still do something.

This isn't a symmetric situation as it is with the FO case above, because range high near errors are much more common than "range short by 50-60m" cases. (You don't just move the aim point, because your only target reference is the object aimed at). So direct fire HE might be marginally less effective than circular bursts model it.

I think they are already less effective than in reality, however, because target height is really only modeled for buildings. You can hit a gun on the fly in real life - that doesn't happen in CM. It is probably a wash.

As for why Russian 120s are given slightly higher blast than Germans, it may well be correct even though they are the same weapons. The HE filler is probably not the same, as the Germans faced greater explosives shortages than the Russians did (thanks in great measure to lend lease, incidentally. The Russians lost a lot of ammo production capacity in the Ukraine).

What isn't probably a wash is high content, high quality explosive shells having the same blast ratings as low content and lower quality explosive ones. The leading example in CMBO was the 4.5 inch, which in reality had no more filler than a US 105, but was given 5/3rds the blast rating in CMBO. Very closely tracking shell weight.

just for reference

[Mr. Tittles]

First with TNT vs. amatol. Usefulness as a cutting charge has nothing to do with explosive effect, and one factor does not describe all uses of explosives. Amatol is made by mixing TNT, a true high explosive, with ammonium nitrate (AN), a much slower, "push" explosive, that happens to have a very high gas volume (980 cubic cm per gram, vs. 710 for TNT). This can be useful for moving rock or cutting a beam, but for shrapnel production what you want is high detonation velocity and high total energy of detonation.

Shrapnel? Who's making shrapnel? Jason are you wearing a spikey WWI German helmet like Colonel Klink had on his desk?

Its fragments baby and I got you dead to rights!

[ November 11, 2003, 11:40 PM: Message edited by: Mr. Tittles ]

[Mr. Tittles]

Note also that these detonation velocities are an order of magnitude larger than shell velocities. The shell is almost standing still compared to the explosion. Yes there is plenty of kinetic energy in the smaller rounds, around the same order of magnitude as the explosive charge (a few millions of joules). But most of it stays in slow moving large hunks. -JasonC

This, more than anything, exemplifys the 'thinking' that leads to pitfalls when discussing HE shell effectiveness.

I think the main trap is comparing detonation velocities with shell velocities. If JasonC had only read the previous posts, he would have seen I am comparing shell velocity to FRAGMENT velocity. and there is a vector effect. Thank you JasonC (jeesh, read more before writing!).

Post note: I was really hoping Emrys would wander in and put one of his own big boots in his mouth but JasonC has beat him to it.

[ November 12, 2003, 02:09 AM: Message edited by: Mr. Tittles ]

[Mr. Tittles]

Here's a visual demonstration of whats going on.

JasonC is running towards me. I am standing still. He is a HE shell. I am a HE explosion. When he gets next to me, I instantaneously wallop his rump with a swift powerful kick. He continues moving forward but one of his ass cheeks goes sideways at a non-orthogonal angle.

Its ironic isn't it?

[ November 11, 2003, 10:59 PM: Message edited by: Mr. Tittles ]

[Mr. Tittles]

I think people should free up their minds and consider:

1. Sometimes things worked well without any design intention for them to.

2. Sometimes 'Goals' leads to failure.

3. What everybody 'knows' is actually different to each everybody but they just don't know it.

4. 'Long and Wrong' describes certain peoples posting style.

5. 'A penny saved' is just a filthy piece of copper that would be better off being a bullet.

6. Some other stuff too.

[ November 12, 2003, 01:35 AM: Message edited by: Mr. Tittles ]

[Mr. Tittles]

Capacity of Loading Plants

http://members.tripod.com/~Sturmvogel/ussbsfig37.html

[Mr. Tittles]

postem-doublem

[ November 12, 2003, 01:02 AM: Message edited by: Mr. Tittles ]

[Mr. Tittles]

Some British thoughts..

PROJECTILES

Technically, projectiles were classed as either 'shot' or 'shell'. The former was solid and restricted to anti-tank and some training natures. The latter were hollow with some kind of filling and needed a fuze to activate the filling at the required moment. In the late 1930s the British started introducing streamlined shells, where the curvature of the ogive was far more streamlined than previously, the radius of the curve being about 10 times the calibre instead of the previous 2 to 4 or so times. This curvature was called the 'calibre radius head' (crh) and usually expressed by two numbers, '5/10' for most WW2 British shells. '5' indicated the length of the ogive in terms of the number of calibres and '10' represented the radius of the circle, in calibres, that gave the curvature of the ogive. Streamlined shells had the suffix letter 'D' with their mark numbers. Some details of shells for each type of gun are in the gun data sheets at 'Guns'. 18-pdr gives an indication of the effectiveness of streamlining, the original design was 2 crh, but in the 1930s a 4/7.5 crh design was introduced (Mk 1C). They were identical in weight and used the same cartridge, but for Mk 1C MV was 0.9 % and maximum range 16% greater.

In most cases projectile bodies were machined from forged and pierced steel billets and to guard against microscopic flaws that could cause a premature in the gun's bore a steel plate was fitted into the outside base of HE shell. The British used general engineering grade steel for shell bodies, '19 ton', which meant they could be machined in the many engineering factories converted to war production, although they moved to higher grade 20 ton steel with the 5.5-inch 80-lb shell. Higher grade steel meant thinner shell walls, which in turn allowed more streamlining, a longer shell and hence more explosive filling for a given shell weight. Interestingly 17-pdr HE used 30 ton and 3.7-inch HAA 27 ton, which probably reflected the need for greater strength to cope with their higher muzzle velocities. While the use of general engineering grade steel facilitated war production its disadvantage was that more of a shell's 'weight budget' was taken up by metal to provide sufficiently strong shell walls, leaving less for explosive. See Table 1 in 'Weight of Fire'.

The standard shell for all guns was HE and its standard weight was when fitted with a standard fuze. However, different fuzes had slightly different weights while different types of filling could result in significantly different weights. For example 25-pdr BE smoke Mk 2D (see below) was only about 21 lb 13 oz, while 25-pdr armour piercing shot was only 20 lb.

HE shells were the most common and until early 1945 the explosive filling was either TNT or Amatol, the latter having been accepted as the standard between the wars. Both of these explosives were less powerful than Lyddite (picric acid) that had been introduced at the beginning of the century, but they were also a lot more stable and less sensitive (harder to detonate including by sympathetic detonation). Amatol was a mixture of ammonium nitrate and TNT, with the ratio expressed as 80/20, 60/40 (the standard mix for general use), etc, where the first figure was the proportion of ammonium nitrate, which could be synthetically manufactured. However, in late 1944 a new and more powerful fill was adopted for shells - RDX/TNT and started to appear in small quantities in 1945, the reason for its introduction was improved fragmentation for anti-personnel effects. RDX (also called cyclonite or hexagen) was a more powerful explosive, about 40% more powerful than TNT, discovered in WW1. However, it was difficult to mass produce with quality and this limited its use until joint Canadian, British and US chemical engineering efforts achieved success in 1943. RDX/TNT remained the preferred British artillery fill for the remainder of the 20th Century.

However, both TNT and Amatol were difficult to detonate and did not give of any smoke when they did so, which often made ranging difficult. This meant that the explosive in the fuze had to be boosted by use of exploders and a smoke compound added to help observers see a shell's burst.

Figure 4 - Cutaway HE Shell

Shells filled with Amatol generally had two exploders, those with TNT only needed one. In the latter case a smoke box (usually filled with red phosphorus) was substituted for the second exploder in smaller calibres. When there was no room for a smoke box the smoke agent was mixed with the explosive filling. The exploders were filled with an intermediate explosive, most usually 'Composition Exploding' (CE) a very energetic explosive (called Tetryl), although TNT crystals was also used when CE supplies were short.

The other main type of shell was smoke. The British had first used smoke shells in 1916. Smoke shells divide into two classes, bursting and burning. The best known of the former being White Phosphorus (WP), although the Wehrmarcht used an oleum & pumice mixture. WP filled shells had a small amount of HE around the fuze's exploder, similar to exploders in HE, to burst them open and disperse the phosphorus, which ignited when exposed to air. The shell case split into large pieces not small fragments. British shells were usually filled with WP through a plug in the side of the shell body. However, the British considered WP somewhat ineffective in most conditions and introduced burning smoke in containers base ejected (BE) from a carrier shell in flight. WP was also more hazardous to store and ship, British rules required that it was usually carried as deck cargo. Nevertheless, WP remained in use with 3.7-inch Howitzers throughout the war because it was more effective in mountainous terrain. It was also used with mortars and was retained with some WW1 era guns.

http://members.tripod.com/~nigelef/ammo.htm

The Shell is the Weapon of Artillery

[Mr. Tittles]

Just some reading material

http://www.du.edu/~jcalvert/phys/bang.htm#Expl

Ammonium nitrate, NH4NO3, is also an excellent explosive, used in certain dynamite mixes (Nobel, 1879) and as a nitrate oxidizer in pyrotechnics. It is very hygroscopic and must be protected against moisture. It decomposes to nitrogen and water, giving very little smoke, by the ideal reaction 2NH4NO3 → 2N2 + 4H2O + O2. The excess oxygen can be used to oxidize some organic material mixed with the nitrate, such as wood meal, starch or diesel oil. Explosives of this type have been widely used since 1867. It is rather insensitive, and must be strongly detonated, perhaps by Primacord or a similar booster. Its density is 1.725 g/cc. Amatol is a mixture of ammonium nitrate and TNT (see below), either 80:20 or 50:50. The nitrate oxidizes the TNT so that no smoke is produced. It was a popular shell filling, economizing on the expensive TNT and stretching out toluene supplies.

[ November 12, 2003, 01:47 AM: Message edited by: Mr. Tittles ]

[Mr. Tittles]

1. Blast: reflection of the weapons explosive destructiveness. Its ability to knock down buildings, bunkers, tracks off tanks, etc. Mostly based on HE content but also influenced by velocity and mass of the incoming projectile. Blast is also tied to dust effects from ground-target conditions.

I would add..

create craters..

depending on mixture, dust particulate from the detonation of fillers own explosive reaction..

[Mr. Tittles]

On 105s, at the muzzle no doubt, I was referring to personal experience that you can in fact hear them when they are coming in, or are shot overhead. They are definitely subsonic by then, at typical artillery ranges (several miles). (You can also see them if you are looking the right way, no surprise).

Lets get real. None have ever been shot at you?! Thats the main point, so your 'experiences' are not applicable.

Jason. Can I safely assume you will disappear from this thread? I want to develop my thesis and your old time 'knowledge' is an impediment.

[Wol]

Just a note of caution: Detonation velocity is less important than characteristic velocity. Shell geometry is much more important than simple charge to to weight ratios - this is particularly important considering semi AP rounds and bombs. Steel hardness has no significant effect on fragment velocity.

Peak overpressure and and shock wave (the stuff that damages structures) is a function of explsive content only. Charge mass to wall thickness ratio (and therefore mass) is the determinant of fragment velocity (thus the importance of shell geometry, current US approximations divide the shell into 4 averaged sections - excluding base and nose). Fragment size is dependent upon the power of the particular explosive, and the quantity of explosive with respect to a given mass of wall casing.

shell velocity adds nothing to 'blast effects', but does tend to change the spread of fragments increasigly (with increasing shell velocity) to a cone of destruction along the axis of the line of flight of the round.

The US (as far as I know) started accurated empirical testing in 1943 following British experience that increasing burster charges in AP Naval shells really did have a significant effect on the fragmentation effects of naval shells and its penetration of adjacent bulkheads. (So a US 16" heavy 2700lb AP shell with a 1.5% explosive D burster has less post-impact fragmentation effect on nearby structures than and less ability to penetrate adjacent bulkheads than a 15" British 1938lb TNT or 60/40 Shellite AP projectile, although a price must be paid in terms of shell strength.)

[JasonC]

I'm sure Mr. Tittles thinks he is saying something - when he gets around to figuring out what it is maybe he will tell us.

So ammonium nitrate extenders are easier to get in quantity when all your nitrate comes from synthetic ammonia, or when your coke industry is maxed, whatever. The Germans used amatol to extend the explosives they could make, for production reasons, not for its effectiveness.

It is less effective than TNT for its weight not more, because it is a slower, less energetic explosive. A ratio from an engineer's report on moving rocks is not shell splinter effectiveness. His own equation sites detonation velocity, which is 33% higher for TNT. Just put the explosives' numbers in your own equation.

If anyone wants to explore the minutae of the German wartime synthetics industry and all its interrelated bottlenecks and substitutes, they are most welcome.

http://www.angelfire.com/super/ussbs/ussbsappa.html

http://members.tripod.com/~Sturmvogel/ussbsappd.html

I don't think tiny bursters or their absence in naval AP ammo is terribly relevant here.

Splinters are made by high energy of the explosion and high detonation velocity. 33% more detonation velocity, all other things being equal, will mean a higher number of smaller fragments going faster, which means better CZ coverage out to longer distances from the burst. Therefore, all other things being equal, a shell filled with TNT will have a larger CZ than one filled with amatol.

Which was the point in dispute, whatever Mr. Tittles imagines. He presented amatol as though it were something like penta or RDX or comp B, a more sophisticate explosive with a higher "effectiveness". It isn't. It is just a more economical one, under some production conditions.

Similarly, of two shells weighing the same amount, if one has twice as much of that weight as explosive than another does, it is going to have a larger CZ. There are such differences even within tube arty shells (as opposed to mortar vs. tube vs. bomb comparisons, etc), thus otherwise similar (in angle of attack, terminal velocity, etc). Brit 25 pdrs and US 4.5 inch had half the explosive to weight ratio of US 105 and US 155, for example.

Shells that were 14% TNT by weight should have larger CZ per unit weight than shells that were 7%-10% amatol by weight. Anybody think they actually do in CM?

[Mr. Tittles]

Originally posted by JasonC:

On amatol, 80/20 gives about 90 of the effectiveness of TNT, while 60/40 gives about 80 of that effectiveness. If the point is to stretch nitrates into overall explosive power that is worth it. If the point is to pack explosive power into each shell it is not. The US used 100% TNT for most arty rounds throughout the war. Some common rounds went to 80/20 amatol. The Germans used 60/40 as a matter of course.

This combines with filler weight differences to make for quite a difference in the explosive power of otherwise similar rounds. Both the US and the German 105 rounds weigh 33 lbs. CM gives them the same blast rating. But in reality the German round was something like 10% 60/40 amatol while the US was 14% TNT. Meaning 4.6 vs. 2.65 lbs TNT equivalent, or more than 50% higher for the US round.

If the CM blast rating of the US 105 were up to a third higher than the German, it would be perfectly realistic. Similarly, a US 81mm mortar round could easily have as high a blast rating as a German 75mm tank round, instead of the half it has in CM. But CM blast ratings contain only minor corrections for shell characteristics besides overall weight.

'vertauscht' means transposed or inverted in German?

Amatol x/y

militärische Sprengstoffe, Deutschland WK II;

gießbare Gemische, i.a. aus x % TNT und y % Ammoniumnitrat (in USA waren x und y vertauscht);

Ausnahmen, siehe: Ersatzsprengstoffe: Amatol 39, 40 und 41 (s.u.) ; s. siehe: Fp.

Amatol 39 (Buchstaben und Zahlen)

siehe: Ersatzsprengstoffe, Deutschland WK II;

gießbare Gemische

Zusammensetzung: 35-45 % Ammoniumnitrat, 5-15 % Hexogen und 50 % TNT bzw. Dinitrobenzol

Amatol 40

militärische Sprengstoffe, Deutschland WK II;

Füllung der V 1-Raketen;

Zusammensetzung: 50 % Dinitroanisol bzw. Dinitrobenzol, 35 % Ammoniumnitrat, 15 % Hexogen

Amatol 41

militärische Sprengstoffe, Deutschland WK II;

Zusammensetzung: 52 % Ammoniumnitrat, 6 % Calciumnitrat, 30 % siehe: PH-Salz, 10 % Hexogen, 2 % Montanwachs

I think German 'Amatol' actually refers to concoctions. But the big point is that when you see 60/40 amatol, when refering to German data, it may be the opposite. It may be Amatol with 60% TNT. This site shows Amatol 40/60 (US ratio: AN:TNT) to be between 6200-7440 M/s. TNT is listed as 6900 M/s.

http://www.pirotex.by.ru/VV/table.htm

I have data that shows the Germans used many different fillings.

JasonC, can you back up this early claim that the US predominately used TNT? I have shown, at least with 75mm HE and 81mm HE, the US must have used BOTH (as well as another) during the war. You may be right, I can only point to the fact that the US did not use Amatol appreciably before the war. I can only assume that they started using it during the war. TNT, when made correctly, is a nice peace time investment. It lasts on the shelf. Amatol, with its sensitivity to moisture, is more of a 'make em and use em' deal. The US must have made a considerable amount of explosives. They had a bomber campaign against two nations. They were supplying other allied nations with raw materials.

But lets let JasonC back this statement of his, if he can. I would then like to continue developing better models/insights into HE shell effectiveness.

[ November 12, 2003, 01:56 PM: Message edited by: Mr. Tittles ]

[Mr. Tittles]

some info...

1.1. Properties of Explosives:

A few physical and chemical properties of basic explosives are summarised in Table 1 (the information has

been mostly assembled from [YIN99], as well as from [NIJ99a] and [NIJ98]):

Name Molecular

Weight

C H N O Density

(g/cm3)

Vapour Pressure

(rel. | Torr)

Preferred

Trace Det.

TNT 227.13 7 5 3 6 1.65 7.7 ppb | 5.8·10–6 (25 °C) Particle (Vap.)

RDX 222.26 3 6 6 6 1.83 6.0 ppt | 4.6·10–9 (25 °C) Particle

HMX 296.16 4 8 8 8 1.96 3.95 ppt | 3·10–9 (100 °C!) Particle

Tetryl 287.15 7 5 5 8 1.73 7.5 ppt | 5.7·10–9 (25 °C) Particle

PETN 316.2 5 8 4 12 1.78 18 ppt | 1.4·10–8 (25 °C) Particle

NG 227.09 3 5 3 9 1.59 0.41 ppm | 3.1·10–4 (26 °C) Vapour

EGDN 152.1 2 4 2 6 1.49 92.6 ppm | 0.07 (25 °C) Vapour

AN 80.05 – 4 2 3 1.59 12 ppb | 9.1·10–6 (25 °C) Particle (Vap.)

TATP 222.23 9 18 – 6 1.2

DNB 168.11 6 4 2 4 1.58 3.8 ppm | 2.9·10–3 (25 °C)*

Picric acid 229.12 6 3 3 7 1.76 7.6 ppt | 5.8·10–9 (25 °C)*

Table 1: Properties of some basic explosives (source: mostly [YIN99], also [NIJ99a, NIJ98]; *: calculated from

[ROS91])

TNT (2,4,6-Trinitrotoluene) is one of the most widely used military explosives, and has been in use for

about the last 100 years (most of the production during WWI and WWII). DNB (1,3-Dinitrobenzene) was

produced in large quantities during WWI (in second place after TNT), and to a lesser extent during WWII.

Picric acid (2,4,6-trinitrophenol) has been the third most produced explosive during WWI, and to a much

lesser extent during WWII. RDX (Hexogen) is more recent, was the second most produced explosive during

WWII and is still in very wide use today, also in plastic explosives2. PETN (Nitropenta) is also used in

plastic explosives. HMX (Octogen) is a very powerful and costly military explosive, which has been

employed in solid-fuel rocket propellants and in military high performance warheads. As general references

see also [YIN99, HAA94].

Military explosives currently used are mostly a combination of TNT, RDX, PETN, HMX, with a number of

organic compounds (waxes, plasticizers, stabilisers, oils, etc.). Examples3 are Composition B (RDX, TNT),

Composition C-4 (or PE 4) (RDX), Detasheet (PETN), Octol (HMX, TNT), Semtex-H (RDX, PETN), etc.

[YIN99].

[Mr. Tittles]

Russian WWII filler info..

http://www.geocities.com/russianammo/Headstamp.html