Medium caliber HE blast values in CMBB

[Andreas]

Originally posted by JasonC:

105mm howitzer rounds are subsonic.

Speed of sound is 331.4m/s in air (temperature dependent). MV for the 10,5cm lFH18 is given as ~450m/s. That would indicate that in direct fire, the round is supersonic, and you would not hear it before impact, if the distance is short enough for it to hit before it has slowed down sufficiently to become subsonic.

Bolded parts are the basic assumptions for it to hold. From the Woensdrecht passage, we know that it was DF. Unfortunately the range is not clear.

Or have I done my calculations wrong?

[Mr. Tittles]

The howitzer was probably firing supercharge at a low angle and the shell was coming strait at the group of officers. You absolutely sure it was not supersonic?

Hearing shells whistle before impact depends on where they impact. If they fly over you, you will hear them. If they are to your sides, likewise, you will hear them. When they come strait at you, they better be moving mighty slow if you are to hear them.

The basic advantage is when a ranging round falls beyond a lethal distance from a unit. They can elect to quickly move away or to dive into/under cover.

Mortars are notorious for giving little warning. High velocity guns are nicknamed crash-booms because the explosion preceded the report of the firing weapon.

[Moon]

Originally posted by JasonC:

CM blast values, on the other hand, do not reflect filler weight differences. Any correction for those differences is second order and minor; the basic determinant of CM blast is simply shell weight. Thus 7 lb 81mm mortar rounds have half the blast of 75mm gun HE, when the filler weight is essentially the same for the two rounds. In CMBO, the 4.5 inch gun, which had very low HE filler weight to shell weight, and in fact had no more filler than a 105, still has much higher blast than a 105, tracking its higher shell weight.

JasonC, actually blast values are not directly used in the game. They are purely an abstract value used solely as an easily-grasped display for the user. It's a feature that has been asked for repeatedly during beta testing, and helps the newbie to get a rough idea of the lethality of a gun.

Internally however, the game algorithms use the real world values of projectile weight and explosive (i.e. TNT/amatol) content to determine destructive effect.

Therefore your observations are correct on the surface, but your conclusions aren't.

Martin

[Mr. Tittles]

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

and M4)

:super normal,normal,or reduced

charges —with 1.93 lbs.super charge,14,000 yds.

range;with normal 1.05 lbs.charge,11,400 yds.

range,and with 0.38 lbs.reduced charge,7200 yds.

range;M4 propelling charge was 1.93 lbs.of super

charge,range of 14,000 yds.;shell contained 1.47

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

Amatol as an alternate);propelling charge was 0.92

lbs.FNH powder (Drawing in 1944 Catalogue,p.

515)

81mm mortar

Firing;mortars Range 13C Fins on shell stabilize it in flight;the fins also cause

nose to strike first.A point-detonating impact type of

fuze is fitted to the nose of the shell.The propelling

charge attached to the base end of the projectile

consists of an ignition cartridge and propellant

increment.The increments of the charge are

removable to provide for zone firing.Ammunition

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

3290 yds.);M36 (10.62 lbs.)(range 300 to 2558 yds.);

and a chemical shell,M57,10.75 lbs.(range 300 to

2470 lbs.)(Photo of mortar in 1944 Catalogue,p.

152).

M43 H.E.shell also used in 81mm mortar:range is

3,300 yds.(1944 AIG,p.280)(according to this

manual,range of M43A1 is approximately the same

as the M43)

Shell,H.E.,M44 also used in 81mm (1944 AIG,p.

285)

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).

Here is data for the US 75mm M48 and US 81mm mortar rounds. They refer to 1944. Notice the Amatol AND TNT mix in the shells. Trimonite also used in 81mm.

Trimonite

High explosive used as a substitute for trinitrotoluene as a bursting charge. Trimonite is a mixture of picric acid and mononitronaphthalene.

Trinitrophenol

Picric Acid.

Trinitrotoluene

(TNT) High explosive widely used as explosive filler in projectiles and by engineers; trinitrotoluol.

[ November 05, 2003, 05:35 PM: Message edited by: Mr. Tittles ]

[Redwolf]

Originally posted by Moon:

</font><blockquote>quote:</font><hr />Originally posted by JasonC:

CM blast values, on the other hand, do not reflect filler weight differences. Any correction for those differences is second order and minor; the basic determinant of CM blast is simply shell weight. Thus 7 lb 81mm mortar rounds have half the blast of 75mm gun HE, when the filler weight is essentially the same for the two rounds. In CMBO, the 4.5 inch gun, which had very low HE filler weight to shell weight, and in fact had no more filler than a 105, still has much higher blast than a 105, tracking its higher shell weight.

JasonC, actually blast values are not directly used in the game. They are purely an abstract value used solely as an easily-grasped display for the user. It's a feature that has been asked for repeatedly during beta testing, and helps the newbie to get a rough idea of the lethality of a gun.

Internally however, the game algorithms use the real world values of projectile weight and explosive (i.e. TNT/amatol) content to determine destructive effect.

Therefore your observations are correct on the surface, but your conclusions aren't.

Martin </font>

[Mr. Tittles]

Characteristics of US Explosives. The table below lists the characteristics and principal uses of US explosives.

Explosive Principal Uses Velocity of Detonation Relative Effectiveness as a Breaching Charge (TNT – 100) Intensity of Poisonous Fumes Water Resistance

(m/sec) (ft/sec)

Black powder Time blasting fuse 400 1,300 0.55 Dangerous Poor

Ammonium nitrate Demolition charge (cratering) 2,700 8,900 0.42 Dangerous Poor

Amatol 80/20 Bursting charge 4,900 16,000 1.17 Dangerous Poor

Military dynamite, M1 Demolition charge (quarrying, stumping, and ditching) 6,100 20,000 0.92 Dangerous Fair

Detonating cord Priming 6,100 to 7,300 20,000 to 24,000 Excellent

TNT  Demolition charge (breaching)

 Composition explosives 6,900 22,600 Dangerous Excellent

Tetrytol 75/25 Demolition charge (breaching) 7,000 1.2 Dangerous Excellent

Tetryl  Booster charge

 Composition explosives 7,100 1.2 Dangerous Excellent

Sheet explosive M118 and M186 Demolition charge (cutting) 7,300 2,400 1.14 Dangerous Excellent

Pentolite 50/50  Booster charge

 Bursting charge 7,450 24,400 Dangerous Excellent

Nitroglycerine Commercial dynamites 7,700 25,200 1.5 Dangerous Good

Bangalore torpedo, M1A2 Demolition charge (wire and minefield breaching) 7,800 25,600 1.17 Dangerous Excellent

Shaped charges M2A3, M2A4, and M3A1 Demolition charge (cutting holes) 7,800 25,600 1.17 Dangerous Excellent

Composition B Bursting charge 7,800 25,600 1.35 Dangerous Excellent

Composition C4 and M112 Demolition charge (cut and breach) 8,040 26,400 1.34 Slight Excellent

Composition A3  Booster charge

 Bursting charge 8,100 26,500 Dangerous Good

PETN  Detonating cord

 Blasting caps

 Demolition charges 8,300 27,200 1.66 Slight Excellent

RDX  Blasting caps

 Composition explosives 8,360 27,400 1.6 Dangerous Excellent

This website claims 80/20 Amatol to be as 1.17 factor to TNT.

UNITED STATES MARINE CORPS

THE BASIC SCHOOL

TRAINING COMMAND

24164 BELLEAU AVENUE

QUANTICO, VIRGINIA 22134-5019

[Mr. Tittles]

Bombs had another important advantage over artillery. A shell fired through an artillery barrel is subjected to tremendous heat and stress. And an artillery piece must be able to fire thousands of rounds without mishap. Consequently an artillery round requires a heavy casing, which lowers the amount of weight of the shell given to explosive power. This is not a problem if one wishes to pepper an area with shell fragments. However, the greater the amount of explosive, the greater the amount of shock created by the explosion. A bomb designer worked within different limits. A bomb left the aircraft with very little stress or friction. Consequently if the so designer wished it was possible to devise bombs that carried very little casing and a large amount of explosive. The result was a shock wave that often created its own fragmentation by destroying buildings, trees, and anything else in its path. The standard 500-pound GP bomb carried about half its weight in pure TNT. Some bombs had lighter casings and a higher percentage of explosive to maximize blast. Fragmentation bombs had heavier casings that were designed to break apart. Later bombs used more complex explosives like amatol, which increased blast by 25 percent. Crews in the South Pacific took whatever they could get.

Because bombs were dropped from a passive position, they could be designed to kill men and damage targets in three ways. One was shock. Because the amount and type of destruction varied, choosing the right weapon for the mission was difficult. However, shock effect, for our purposes, is probably best measured by the ability of the bomb to cause damage at a certain distance. The damage itself was done by a tissue of air propelled by the explosion; it had tremendous pressure initially but dissipated rapidly. According to U.S. Army figures, an enemy in the open would suffer a ruptured eardrum from a 100-pound bomb dropping within a radius of thirty feet. If a 500-pound bomb was dropped the radius increased to forty to fifty-five feet. A 1,000-pound bomb would rupture an eardrum within an eighty- to ninety-foot radius. Killing was a different matter. A 100-pound bomb would kill 50 percent of men in the open at a radius of ten feet. A 500-pound projectile had the same effect at fifteen to eighteen feet. A 1,000-pound bomb would kill half the enemy within a radius of thirty feet. (Please note that these figures are based on radius, not diameter.) Obviously there was a law of diminishing returns here, familiar to any study of mortality and weaponry. Yet the exchange was all too clear. There were many solo bomber missions in the South Pacific, but for the most part the bombers came in units. All of these figures given for shock—and let us remember that a man with a broken eardrum was probably out of the campaign—were multiplied many times by the fact that so many bombs were dropped.

Secondly, bombs killed with fragmentation. Fragments came from two different sources. One was from the casing of the bomb itself, usually a soft metal. The other was the debris blown into the air by the shock wave. Fragmentation bombs heavier than 100 pounds were almost always aimed at enemy infantry (whether attackers could see the enemy or not), aircraft on the ground, and antiaircraft installations. Officers knew that most of the men would be prepared for air attack at air bases and important positions in an infantry position. Therefore bombs were set to explode above the ground. The results were wicked and explain better than any anecdote why smart soldiers dug deep. If a 500-pound bomb exploded twenty or thirty feet above a small area, the chances for injuring a soldier who was in the open or a shallow foxhole (what the military called a 10-degree fortification) were 100 percent. A deep trench, particularly if made with angles, reduced the chances of casualties to less than 30 percent. No field fortification could prevent complete catastrophe if there was a direct hit, but digging a trench as deep as a man is tall made the victim far less vulnerable to air attack. Yet with enough bombs falling some men on the ground would die or suffer wounds—whether physical or psychological—regardless of precautions. If a bomb struck an enemy advancing to the attack above ground, the results could be catastrophic.

[Redwolf]

Good stuff, thaks.

This is also the reason why rocket artillery (or MLRS today) delivers so high blast values, the velocity and hence stress the projectile undergoes is a lot less than when fired from a gun.

[Mr. Tittles]

While jasonC has been roundly spanked in this thread, I will put my neck out and declare the following:

The game probably does not take into account shell velocity, angle of descent and possible fuze effects.

I often wonder about fragment velocitys (well.. every now and then), and the relationship between other fragment forces.

The fragments from a HE projectile/bomb typically are directed to the sides of the shell. The shell usually was travelling in a forward motion before being blasted to bits. The forward motion and the sideways motion would have a vectoring effect. If the velocity of the shell is substantial enough, and the fragment HE driven velocity is slow enough, then this has considerable effect on the target end. In the case of low angle descent, it could possibly be beneficial!

[Mr. Tittles]

Heres a hypothetical example.

A tank gun fires a HE shell. It is travelling at 2500 fps. It hits a tree branch in an outer tree of a woods and detonates on superquick mode.

The detonation of the HE train within the shell is probably a millisecond or so. Still, this allows the shell to travel about 2.5 feet! I often wonder about these claims of airbursts and how quick it needs to be.

Anyway, the shell explodes and fractures into fragments of varying sizes. The front and rear parts usually forming large scabs and the sides 'balloon' out forming a collection of different sized objects.

The front piece would have an additive velocity vector. Its velocity would be the sum of the forward motion of the shell, and the additional kick it got from the explosion of the HE. Since larger fragments may get less HE kick (just like a gun trying to fire a larger bullet gives it less velocity), this would have to be taken into account.

The rear piece, typically being thicker, would get a double penalty. Its forward motion would fight the HE kick. Its large and big and trying to go backwards after being thrown forward.

The sides of the shell are even still more interesting. They not only get a forward velocity and a HE kick velocity but an additional rotational velocity from the spinning of the shell. This rotational velocity to translational velocity component can be somewhat helpful, especially for the larger chunks. An interesting thing is that the rotational component is independant of fragment size (as long as the fragments are coming from the sides).

Lets take the case of a shell spinning at 20,000 rpm. Its a 105mm howitzer round (4.134"). The calcs give 360 fps JUST from the rotational velocity being converted to translational energy. The larger the round, the greater this component for a given rotational velocity. For the larger chunks of metal, this could be a significant boost. Also, for shells like bursting smoke shells (of any type), this makes for deadly projectiles. Note that mortars that are smooth bore do not get this velocity component. A 105mm shell weighing 33 lbs loaded has something like 28 pounds of metal.

Lets take the case of a 105mm bursting smoke round that is coming in at 45 degrees and detonates up in the trees. For the sake of argument, lets assume its coming in at 500 fps. lets further assume that the bursting charge ONLY cracks open the shell and gives little to no kick velocity to these fragments.

The result would be a 'rain' of large fragments with a conical shape travelling at 616 fps. These would be long slivers of metal with some weight to them. The front of the shell would just have the 500 fps! What about the back? well, in this case, it would travel forward at 500 fps also! In any case, theres 28 lbs of fragments flying with deadly velocity.

But in reality, even a bursting smoke shell WOULD give SOME HE kick. The reason for this is that its design is relying on the HE to ignite/spread the smoke chemical. If its a point detonating ground burst, then the chemical would be shot into the ground if it is not dispersed quick enough. The bursting charge would need the strength (brisance) to not only crack open the shell itself but also eject the chemicals outward.

My gut feeling about the relationship between shell wall thickness/material and bursting charge and effectiveness of HE shells (or any bursting shell) is that it is only part of the equation. Angle of descent, forward velocity, height of detonation, etc are all major players.

Hopefully, the artillery model and direct fire model can reflect these realities.

[ November 07, 2003, 10:22 AM: Message edited by: Mr. Tittles ]

[Redwolf]

Originally posted by Mr. Tittles:

The game probably does not take into account shell velocity, angle of descent and possible fuze effects.

I often wonder about fragment velocitys (well.. every now and then), and the relationship between other fragment forces.

The fragments from a HE projectile/bomb typically are directed to the sides of the shell. The shell usually was travelling in a forward motion before being blasted to bits. The forward motion and the sideways motion would have a vectoring effect. If the velocity of the shell is substantial enough, and the fragment HE driven velocity is slow enough, then this has considerable effect on the target end. In the case of low angle descent, it could possibly be beneficial!

In CMBO and CMBB the impact is definivly an even circle around the point of im0pact.

Question: If there is cover between a HE shell impact and a squad, but the squad itself is not in cover, is that taken into account? Is a "shot" from a HE burst point towards a squad subject to the same effect as a smallarms shot through the same environment?

I need a drawing...

The speed of the shell plays a role in CM. A slow shell has a smaller fall pattern on a horizontal target area (although it is subject to more range estimation errors before it zeros in).

[Mr. Tittles]

Originally posted by redwolf:

Question: If there is cover between a HE shell impact and a squad, but the squad itself is not in cover, is that taken into account? Is a "shot" from a HE burst point towards a squad subject to the same effect as a smallarms shot through the same environment?

Thats a good question. If the game doesn't,then airbursts are even more deadly.

[Mr. Tittles]

Ive given it some thought and have come to the conclusion that blast values, at least for mortars, should reflect the varying degrees of deadliness of these weapons. Its more an Apples to Apples thing.

Mortars generally land a shell in a perpendicular fashion. This is because the fins align the shell. Since most mortars are smooth bore and have no shell spin, they are basically bombs with varying wall thickness/different materials and HE fillers. the game probably approximates the deadliness of shells as circular and this corresponds to mortars also.

Heres a comparison of German (G) and Soviet (S)

120mm S:125 G:119

82mm/81mm S:26 G:26

50mm S:5 G:6

The blast values must come from somewhere. What is the formula?

[ November 07, 2003, 07:25 PM: Message edited by: Mr. Tittles ]

[Mr. Tittles]

http://www.battlefield.ru/guns/project_4.html

This site claims that German 120mm and Soviet 120mm are identical in weight/charge. They are really the same weapon. The soviet is Iron cast. Was the German different?

[Redwolf]

The Germans copied the Russian 120mm mortar after Barbarossa, it is the same weapon.

Just don't mix it up with an entirely different rare German mortar with caliber 120mm which was used in WW1.

[Mr. Tittles]

I wonder if the Germans didnt capture factories for these weapons and ammunition.

Perhaps the sights may have been different.

[Mr. Tittles]

I would like to turn to a discussion of the original matter: namely the effectiveness of small (50mm) HE. I believe the first post brought it up.

http://www.geocities.com/russianammo/57mm.html

Please look at this page and study the 45mm russian rounds in cutaway drawings and chart information.

http://www.geocities.com/russianammo/p45mmHE.jpg

Some HE highlights:

1. The 45mm HE round has a very low velocity of 343 M/s

2 It has a 135 gram payload. About 1/3 of a pound. Early in the war its TNT changing to a mixture A-IX-2.

3. HE round is very long for a round of its size. Almost like a rocket.

4. HE shell weighs 2.15 Kg (about 4.75 pounds)

5. Rather thick walled for such a low velocity weapon (343 M/s)

6. Interesting thinning of walls and large concentration of HE towards front of shell.

To look at the stats, this weapon does not appear to have a devastating HE round. The fact is, its a devastating round when fired by this weapon!

In front of Seoul 2/5 from the 104 fights without a single heavy gun in action. We'd run into a swarm of 45mm AT guns, and they had sniped our heavy guns out of existence. Those 45mm AT guns fired a round that you could see leave the barrel and proceeded along like a red hot baseball. You could see them coming if they weren't aimed straight at you. Chilling.

http://www.rt66.com/~korteng/SmallArms/30calhv.htm

The reason for its deadliness? The ability to put a HE round , with precision, against a position. A sand-bagged HMG position would offer little in the way of cover.

This weapon fired a cannister round with a higher muzzle velocity than this HE round. the AP round was 820 M/s.

The German 50mm HE round was also known for being effective for its size. The Germans certainly made enough of them.

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

50mm Sprgr.

(1939)285.5

(1941)336.6

(1942)2426.3

(1943)3164.5

(1944)1206.5

(1945)34

The Germans made 1.2 million of them in 1944?

Another site with 5 cm production numbers (in german)

http://www.lexikon-der-wehrmacht.de/Waffen/panzer3-R.htm

If anyone can post data on this HE round, especially a cutaway, it would be appreciated.

[ November 08, 2003, 02:47 PM: Message edited by: Mr. Tittles ]

[Mr. Tittles]

http://www.inert-ord.net/russ02i/mort_at/R5082.html

This site shows photos of mortar ammo.

[Mr. Tittles]

Sp38 žÖ’e(HE)550m/s 1.86kg(3.3kg)¤165g(280g)

¤ ’eŠÛ’· 224mm(503mm) –òä° 419*77ƒÓ

I believe this refers to the Spr 38 5 cm HE round (L60).

Velocity is 550M/s

Weight is 1.86 kg (projectile)

HE filler is 165grams (0.363 pounds)

Length is 224mm

This compares with the 45mm as being a faster round, less weight but more HE. It would be very accurate and a precision delivery system. Its deadliness would be the ability to put these HE rounds where they were needed. The added velocity not only increase precision buts adds a punch to the HE/fragments.

For targets with a height signature, like buildings, bunkers, etc; it would be deadly. When firing from a height difference, such as across a small valley at targets on a opposing slope, it would be deadly. its main drawback would be when on extremely flat terrain against 'flat' targets. The slower 45mm round would be more capable in these situations. These occasions are usually not that common anyway with intervening terrain/brush. Also, ATGs usually would not expose themselves for such targets, artillery/mortars would be more than adequate.

[ November 08, 2003, 03:14 PM: Message edited by: Mr. Tittles ]

[The Green Rascal]

I'm still following this thread and again want to thank the contributers, you really know your ammo.

ISTM that there are so many factors involved that it would be impossible for everyone to agree on one single number as a 'blast value'. However most people seem content with the way it is in CMBB, but obviously a couple aren't.

It's a dead issue in as much as it would never be patched anyway, but I hope this thread continues as I'm still 'on the fence' and learning all the time.

[Mr. Tittles]

The German 50mm HE is 8.8 inches long and two inches across. The Soviet 45mm is also very long in length compared to its width.

I think there is a cutoff point where the accuracy does not payoff if the payload is too small. A 2 pr. with 0.125 # of filler starts to drift into a 'big-bullet' catagory. You have to actually hit someone or someones weapon practically. Maybe there are 37-40mm AA weapons that do chunk up larger payloads but 20mm, to me, are very large bullets.

Someone metioned that the effects of HE/Blast are circular in the games representation. This would be a big booboo. In the case of mortars, its fogivable but arty and direct fire is much different.

[Mr. Tittles]

Can someone please post the US 60mm, 81mm and 4.2" mortar blast numbers from CMBO?

[Mr. Tittles]

Just soem real oddities:

The cartridges shown above are for the German MG 151/20 (20x81):

"Minensprenggranate mit Zerleger" (HEI-SD) mine shell, m=92,0g, l=82,9mm, 18g high explosive, Vo=785m/s, ol=146,1mm, 14,8g Nz.R.P. (1,3x1,45/0,2) propellant, electrical primer "J", headstamp: exw | 8 | 45 , yellow projectile with green band below fuze, black markings: M El exw 91 45 Mv exw 263/44 ,

"Panzerbrandgranate Phosphor ohne Zerleger" (API) Phosphorous shell, m=115g, l=80,0mm, 3,6g White Phosphorous in sealed Aluminum container, Vo=720m/s, ol=145,5mm, 14,8g Nz.R.P. (1,3x1,45/0,2) propellant, percussion primer, headstamp: wg | 593 | 44 , black bullet with blue band above bourolet, white

markings: Ph edq 335/44, stamped in markings: eel 147/44

If these are 20mm, then the shell on the left has a 1-2mm wall thickness. Also interesting is the thicker walled white phos companion!

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

[ November 08, 2003, 10:30 PM: Message edited by: Mr. Tittles ]

[Redwolf]

Originally posted by Mr. Tittles:

50mm Sprgr.

(1939)285.5

(1941)336.6

(1942)2426.3

(1943)3164.5

(1944)1206.5

(1945)34

The Germans made 1.2 million of them in 1944?

Well, the 50mm PaK was still one of the backbones of the very poor infantry divisions in occupied territories and also of security units. Those are likely to face infantry rushes and they would need any firepower they could muster, artillery was probably not readily available.

If that theory is correct it also means the 50mm HE shell would at least be moderately effective, otherwise they would just place more MGs.

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.

[Andreas]

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.

ATGs as well at that stage. Maybe as much as one platoon per division. Also, you need to deduct numbers for training, in transit, in stores, etc. Ammo numbers in relation to number of guns always seem high to me, just look at the production number of rounds for the sPzB41, compared to the number of guns produced. (2,797 guns, 512,600 HE rounds and 1,602,800 AP rounds produced over the production run - I have my doubts that the average sPzB41 managed to squeeze out 750 rounds).