Medium caliber HE blast values in CMBB

[Mr. Tittles]

http://www.panzertruppen.org/heer/artilleria/campana/lefh18.html

105mm German Howitzer

[88mm]

Originally posted by Andreas:

Wouldn't trust that Belgian website.

Jon, thanks for the info.

May i ask why :confused:

Seems some valid information and nothing special, so why it should be dubious information is beyond me...

[Wol]

A note on tree bursts.

any folliage which is sufficiently dense to activate the fuse is likely to increase the rate of descent relative to its horizontal trajectory in the case of guns. In all cases it means that shells are more likely to detonate before hitting the ground casuing more fragmentation damage and blast damage as energy will not be wasted in crater formation. Of course heavily protected structures are less likely to suffer direct hits.

As I recall, in the Hurtigen Wald, the Americans had a hell of a time from tree splinters caused by German Arty before the folliage was largely destroyed.

How about we turn attention to zones of effect translated into CMXX (necessarily simplified)

say

Mortars and offtable howitzers - circular

Howitzers off table guns - intermediate butterfly

other guns standard flat trajectory butterfly

one value for fragmentation vs soft targets and (modifed fo use against AFVs), possibly combined with another for blast effects on structures

[Andreas]

Originally posted by 88mm:

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

Wouldn't trust that Belgian website.

Jon, thanks for the info.

May i ask why :confused:

Seems some valid information and nothing special, so why it should be dubious information is beyond me... </font>

[Mr. Tittles]

In any case, the Spanish (IF we can trust those Spaniards???) website seems to show that using charge 5 and 6 are supersonic at the muzzle. Using these charges at ranges described in the FO's account would support the assertion that they recipients would not hear it coming.

Not to beat a dead horse but human reaction time, being what it is, would need 0.4 seconds to start doing something EVEN if the shell was sub-sonic.

Lets suppose a short barrelled IG pops a round at you. You hear 'BOOM' (guns report) but the 'CRASH' (shell detonation) is only lagging by 0.5 seconds.

You had a whole tenth of a second to respond and take appropriate action. Was it enough time to even get a proper pucker factored? This is all assuming that it is the only event you can focus on.

[Mr. Tittles]

Originally posted by Wol:

A note on tree bursts.

any folliage which is sufficiently dense to activate the fuse is likely to increase the rate of descent relative to its horizontal trajectory in the case of guns. In all cases it means that shells are more likely to detonate before hitting the ground casuing more fragmentation damage and blast damage as energy will not be wasted in crater formation. Of course heavily protected structures are less likely to suffer direct hits.

As I recall, in the Hurtigen Wald, the Americans had a hell of a time from tree splinters caused by German Arty before the folliage was largely destroyed.

How about we turn attention to zones of effect translated into CMXX (necessarily simplified)

say

Mortars and offtable howitzers - circular

Howitzers off table guns - intermediate butterfly

other guns standard flat trajectory butterfly

one value for fragmentation vs soft targets and (modifed fo use against AFVs), possibly combined with another for blast effects on structures

I think such a thing would be in the realm of CMII. Since the demo for CMAK is out, it may possibly be CMII time.

I am guessing but would venture that the game resolves HE effects through weight of shell and HE payload and HE type. Since arty is generic and there is no range consideration (and descent angle).

Blast value are something different again. They are probably a simpler plug-in formula. As far as I know, no one knows how either the game resolves HE or generates blast numbers.

[Wol]

I am pretty sure that the HE values are solely dependant on calibre, and not even based on consideration of effective fragments per unit area (which is wrong anyway) or fragments or value at range per linear metre of circumference

[Mr. Tittles]

[ December 04, 2003, 08:02 PM: Message edited by: Mr. Tittles ]

[Mr. Tittles]

Heres a 50mm mortar round that has most of its fragments recovered.

[Mr. Tittles]

Heres a 50mm gun HE round (50mmL42 or L60) that has its fragments recovered.

Remember the pretzel test?

[Mr. Tittles]

General comments about the fragmentation of these two projectiles:

1. Mortar round has more uniform size distribution. This is because of the more spherical shape ('bomb' body) compared to the cylidrical shape of the 50mm shell. Mortar rounds typically are thin walled and have a high HE percentage by weight. The tail section typically is blown off in one piece and is shot vertically (back up). They come down again and are not a casualty causing mass typically.

2. The 50mm shell is greater in mass (or mass under HE effect). The 50mm shell rear cap broke off into a round piece. Large sabers are evident.

So which is more deadly in CM terms?

If there is any doubt about the German 75mm HE shell being VERY deadly, than look at this...

[Mr. Tittles]

Since I love to share (unlike certain Germans who won't even translate pantherFiebels for us)...

http://history.amedd.army.mil/booksdocs/wwii/woundblstcs/default.htm

This is a great resource. But some of the data includes very graphic pics of corpses.

Here is the webpage with the best data

http://history.amedd.army.mil/booksdocs/wwii/woundblstcs/chapter1.2.htm

[ January 09, 2004, 01:32 PM: Message edited by: Mr. Tittles ]

[Mr. Tittles]

This data is very useful. Its the german 81mm mortar bomb. The gray areas show fragments below a casualty causing threshold. The horizontal lines give velocity spreads with the small vertical tick showing the mean.

A general statement is that much of this cast iron bomb has been blown to very small particles. Many of the small particles are just wasted. A case of too much HE, too thin a wall and too weak a material (cast iron)?

[ January 09, 2004, 01:42 PM: Message edited by: Mr. Tittles ]

[JasonC]

I think what the last really shows is that everything within 10 yards is going to be peppered by thousands of incapacitating small fragments, while a few larger ones will carry out to 80 yards.

Making for a 10m KZ, with a "danger" zone 80m in radius against full exposed personnel. Huge, in other words. Several hundred large projectiles in that larger zone. Just not all horizontal, or they'd cover even that large a circle quite effectively. A mortar fire mission is going to spread thousands of those over an area up to 200 yards across (CZ width plus typical scatter from the aim point).

[Mr. Tittles]

Uh, its a trick question to see if anyone is paying attention.

The fact is, again, its the price you pay. Just like the pretzels, theres waste.

Ideally, we might want the mass of the shell to blow into fragments all within a narrow size range with identical velocitys and a well defined casualty zone and safety zone.

But the reality is that we want the most MASS to fall into an acceptable RANGE and take the big and the small with it. So the result is that we have a small kill zone and a large danger zone. Not exactly optimal perhaps. A larger kill zone with a smaller danger zone being prefered.

This data fixates on fragments per pound but it should really fixate on effective fragments per pound. 40% of the fragments fall into the small fragment size group (really overkill in the sub-10 yard range and swarf). It would be nice to know the mass percentage of the shell this represents.

[ January 11, 2004, 09:56 AM: Message edited by: Mr. Tittles ]

[Mr. Tittles]

Originally posted by JasonC:

I think what the last really shows is that everything within 10 yards is going to be peppered by thousands of incapacitating small fragments, while a few larger ones will carry out to 80 yards.

Making for a 10m KZ, with a "danger" zone 80m in radius against full exposed personnel. Huge, in other words. Several hundred large projectiles in that larger zone. Just not all horizontal, or they'd cover even that large a circle quite effectively. A mortar fire mission is going to spread thousands of those over an area up to 200 yards across (CZ width plus typical scatter from the aim point).

I did some quick math and took the large and medium fragments (~2000) and divided them into a half spherical shape of 10 yards (you mix yards and meters by the way) radius. This gives about 3.2 peppers per square yard. Since mortars do fan the spray close to the earth and not spherically, I assume a spray about 25-35 degrees. So tripling it gives 9-10 peppers per square yard. A standing man probably is about a square yard so he would catch multiple casualty causing fragments even at 10 yards (note:even if standing he would only be in about 11 degrees of the 30 degree spray, even this close, so always duck when mortars drop on you). Closer to the impact would be deadlier with all the small fragment group and blast from the HE adding in.

But the further away, the less spray. The angled spray would largely miss a standing man at 20 yards. Perhaps 3/5-4/5 going over his head. The middle group of fragments also loses steam and the small fragments (which were just extra shredders inside the 10 yard radius anyway) are useless. The odd chance of being struck at 80 meters (even the large group of fragments is losing steam) is overstated by JasonC. The density of fragments is very small considering angular spray. This extension of casualtys is really a hindrance since its more a threat to attacking friendly troops in most cases. I would characterize the kill zone to be around 5-6 yards, 100% casualty zone around 10-12 yards, and reduced casualty zones extending to about 40 yards. Danger zone would be to 80 yards or so.

Some mortar shells like the US 81mm heavy and 4.2 inch did have a cylindrical shape and would put out a great amount of fragments nearly parallel to the ground.

But the real important question is: How effective is the fragmentation of the mortar shell? It may actually be pretty damn good.

I tried multiplying the average size (taking the endpoints of the range of masses and dividing by two) and then multiplying by the number of fragments in that range. The total mass is greater than the empty mortar shell mass but it gives a general idea. The large fragment size group (arguably the most effective), may account for close to 2/3rds the mass of the shell. The middle fragment group possibly slightly less than a 1/3 and the small group maybe 5% or so. Not bad really. The waste group, the smallest, does not represent that much of the mass of the shell.

[ January 10, 2004, 09:31 AM: Message edited by: Mr. Tittles ]

[Mr. Tittles]

Here is a cutaway of a Japanese 81mm mortar shell. Notice the thin walled construction, large HE mass. The front of the shell would produce large fragments and these would be blown strait into teh ground.

Heres the same shell fragmented..

[ January 10, 2004, 09:46 AM: Message edited by: Mr. Tittles ]

[Mr. Tittles]

TABLE 5.—Hit probability for human targets, Japanese grenade discharger and mortar shells

Distance of panels from burst (radius of circle in yards)

Probable number of hits for type of shell

Type 89 grenade discharger 81 mm. mortar 90 mm. mortar

5 ***********1.56 4.4 5.7

10 ***********.39 .55 .7

15 ***********.17 .16 .21

20 ***********.10 .07 .09

25 ***********.06 .04 .05

30 ***********.04 .02 .03

The reader should note that this was just one test. Under different circumstances, results could also be expected to differ. For example, a mortar shell does not hit the ground perpendicularly when fired for effect. The more acute the angle a shell assumes when striking the ground, the more the distribution of fragments will vary from pure randomness in all directions. Those emanating from the upper surface will go high into the air, those from the sides will come closest to a random dispersion within limited bilateral areas, and those on the underside of the shell will imbed themselves in the ground. This results in a butterfly pattern of dispersion which is ascribed to many types of shells. While the foregoing experiment arrived at some figures for the dispersion of fragments from these Japanese missiles, it did not tell what the wounding capabilities of the hits were. This is the core of the subject of wound ballistics and will be fully developed in later chapters of this volume. Neither could the study just described determine by actual count the number

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of fragments produced by each type of shell. Of the fragments which were recovered, their size was generally small, about one-eighth to one-sixteenth of an inch in diameter.

A study conducted in the Zone of Interior in December 1944, however, had as its purpose the recovery of as many fragments as possible from the detonations of each of five 81 mm. mortar shells. From 542 to 696 fragments per shell were recovered. The mean was 608.6 fragments per shell. This corresponds remarkably well with the sum of the entries in the column pertaining to the number of hits for the 81 mm. mortar calculated for full coverage of circles in table 4. Figure 11 shows the number, size, and shape of the fragments recovered from one of the five shells tested.

FIGURE 11.—Fragments recovered from Japanese 81 mm. mortar shell exploded under test conditions in Zone of Interior in December 1944.

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26

The foregoing studies were presented to give the reader an appreciation of the wounding potential of Japanese mortar shells as he reads subsequent chapters of this volume. It would have been desirable to note the initial and terminal velocity of the fragments and their weight, since the actual wound production of a missile is, to a great extent, a function of its mass and velocity. These data were not available, unfortunately, but it can be assumed, based on the initial velocity of fragments from other mortar shells of similar properties, that the initial velocity of fragments from the Japanese 81 mm. shell was over 2,500 f.p.s. The weight of the fragments of the Japanese 81 mm. mortar shell can be estimated in that the average gross weight for one shell of fragments collected from detonations of the December 1944 test was 5.50 pounds. Thus, it took more than 100 fragments of the Japanese 81 mm. mortar shell to make 1 pound of steel. These data, taken in conjunction with the distribution data presented, should give the reader a good idea of the value of the mortar in ground combat—a weapon which was so fully exploited by the Japanese.

The German 81mm fragments were greater in number. Notice the chance of catching a fragment in the chart. The Japanese 81mm does not have the intense 'peppering' effect of the German 81mm.

The Japanese 81mm would have an extended danger zone also. Notice the probability falloff too. Theres a 1 in 14 chance at 20 yards. theres only slightly more than half a chance at 10 yards!

[ January 10, 2004, 09:58 AM: Message edited by: Mr. Tittles ]

[Mr. Tittles]

TABLE 5.—Hit probability for human targets, Japanese grenade discharger and mortar shells

Distance of panels from burst (radius of circle in yards)

Probable number of hits for type of shell

yards**Type 89 grenade discharger, 81 mm. 90 mm.

5 ***********1.56 4.4 5.7

10 ***********.39 .55 .7

15 ***********.17 .16 .21

20 ***********.10 .07 .09

25 ***********.06 .04 .05

30 ***********.04 .02 .03

This data shows the grenade discharger outperforming the 81mm from 15 yards outward.

I would interprete this to mean the small shell had a rather efficient fragmentation. The nature of these hits, or qualitative value, would depend on the size/velocity of the fragments which the test does not specify.

The test statically fired these shells on the ground, in a vertical orientation, with the nose buried one inch into the ground. Not a bad test but possibly the velocity of the round (or even spin in rifled examples) might also be factors.

[ January 11, 2004, 10:00 AM: Message edited by: Mr. Tittles ]

[Mr. Tittles]

B-5. EFFECTS OF COVER ON HIGH-EXPLOSIVE ROUNDS Enemy forces will normally be either standing or prone. They maybe in the open or protected by varying degrees of cover. Each of these changes the target effects of mortar fire. a. Surprise mortar fire is always more effective than fire against an enemy that is warned and seeks cover. Recent studies have shown that a high casualty rate can be achieved with only two rounds against an enemy platoon standing in the open. The same studies required 10 to 15 rounds to duplicate the casualty rate when the platoon was warned by adjusting rounds and sought cover. If the enemy soldiers merely lay prone, they significantly reduce the effects of mortar fire. Mortar fire against standing enemy forces is almost twice as effective as fire against prone targets.

b. Proximity fire is usually more effective than surface-burst rounds against targets in the open. The effectiveness of mortar fire against a prone enemy is increased by about 40 percent by firing proximity-fuzed rounds rather than surface-burst rounds. The steeper the angle of the fall of the round, the more effective it is. c. If the enemy is in open fighting positions without overhead cover, proximity-fuzed mortar rounds are about five times as effective as impact-fuzed rounds. When fired against troops in open fighting positions, proximity-fuzed rounds are only 10 percent as effective as they would be against an enemy in the open. For the greatest effectiveness against troops in open fighting positions, the charge with the lowest angle of fall should be chosen. It produces almost two times as much effect as the same round falling with the steepest angle. d. If the enemy has prepared fighting positions with overhead cover, only impact-fuzed and delay-fuzed rounds will have much effect. Proximity-fuzed rounds can restrict the enemy's ability to move from position to position, but they will cause few, if any, casualties. Impact-fuzed rounds cause some blast and suppressive effect. Delay-fuzed rounds can penetrate and destroy a position but must achieve a direct hit. Only the 120- mm mortar with a delay-fuze setting can damage a Soviet-style strongpoint defense. Heavy bunkers cannot be destroyed by light or medium mortar rounds. B-6. EFFECTS OF TERRAIN ON PROXIMITY-FUZED HIGH-EXPLOSIVE ROUNDS The multioption fuze functions best over open, firm soil. Snow or sand can cause it to function low or on impact. Water or frozen ground can cause it to function early. If proximity-fuzed rounds are functioning high, they are still effective. The HOB can be reduced by using the NSB setting on the fuze. It cannot be increased except by choosing the steepest angle of fall possible. a. Proximity-fuzed rounds fired over built-up areas can detonate if they pass close by the side of a large building. They can also function too high to be effective at street level. (Impact fuzes are the most effective in heavily built-up areas.) b. In dense jungle or forest, proximity fuzes detonate too early and have little effect. Impact fuzes achieve airbursts in dense forests, and delay fuzes allow rounds to penetrate beneath the heavy canopy before exploding.

http://www.tpub.com/content/USMC/mcwp3152/css/mcwp3152_237.htm

Some interesting info. WWII mortar rounds did not have the proximity capability. Some noteworthy info is the angle of attack, cover, etc.

[Mr. Tittles]

The HE 88 mm. shells tested were filled with amatol (43/57) and weighed approximately 22½ pounds. The external diameter was 88 mm. (approximately 3½ inches), and the average wall thickness was 0.60 inches. When fired against ground targets, a percussion or time fuze was employed. Two rounds were detonated in January 1943 (fig. 29). The rounds when empty weighed 19.17 and 20.37 pounds. For the first shell, 84.6 percent of fragments—1,488 pieces, 16.2 pounds—were recovered. For the second shell, there was a 78.6 percent recovery consisting of 1,543 fragments weighing 16 pounds. The number of fragments per pound in this experiment was not quite 95, one of

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FIGURE 29.—Fragments recovered from a German 88 mm. high explosive shell.

the lowest ratios encountered so far. This finding is actually more apparent than real when one considers the low percent of recovery. The smaller fragments, which are many, were probably not recovered.

Other static detonation tests of the 88 mm. HE shell were conducted. The basic data included fragmentation results and the mean, minimum, and maximum velocities of fragments over the first 10 feet. From this basic data, the data shown in figure 30 were derived. The method of derivation was basically the same as that explained in the preceding section on mortar ammunition (p. 53).

[Mr. Tittles]

I think the 88mm data above shows that Amatol is not the weak sister of TNT. The data shows a good fragmentation pattern and deadly velocity effect. In certain shell casing material types, TNT may not be ideal.

These fragments are much larger than the 81mm mortar fragments (German). They are also less in number but many were not recovered (more than likely very small).

[Mr. Tittles]

A comparison of the 81mm and 88mm would reveal that many of the 88mm fragments are typically going into the ground or strait into the air. This is assuming a ground burst.

The mortar will land near vertically in orientation. This will deliver fragmentation from the sides of its shell casing around the point of impact. The front of the shell and the rear account for waste. If many fragments are too small, they will be short ranged and just overkill in a small radius area that is already covered.

The 88mm effectiveness varys greatly with burst type (ground, tree, etc).

[Mr. Tittles]

Two 50 mm. HE shells for German AT guns were detonated by U.S. Army ordnance personnel. While the specific model of the shells tested was not identified, the weights, empty, of the two specific rounds tested were 3.52 and 3.54 pounds. A total of 202 fragments weighing 3.29 pounds was recovered from one shell, and 193 fragments weighing 3.46 pounds were recovered from the second (fig. 26). This made the percent of fragments recovered 93.4 and 98.3 percent, respectively. Taking, arbitrarily, a ratio of 200 fragments for 3.35 pounds of metal, the number of fragments for 1 pound of metal, a rough measure which was previously adopted for comparative purposes, becomes 60 in this case. It must be noted in this and the other examples for which this rough approximation was calculated that, in all probability, the unrecovered portions represent large numbers of extremely small fragments which would greatly increase the total number of fragments if they could have been recovered and counted. On the other hand, it was previously shown that these minute fragments have considerably less wounding potential. If, as was stated, one dimension of shell fragments is usually a function of the thickness of the shell wall, then many of these extremely small pieces must be sliver shaped. They might not incapacitate a soldier immediately, but it is obvious that they could

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become real surgical problems when their localization and removal is mandatory, such as in the case of foreign bodies in the eyeball.

FIGURE 26.—Fragments recovered from one of two 50 mm. high explosive shells of a German antitank gun detonated in Zone of Interior.

Since this is basically the focus of the thread, medium caliber HE, its worth going over again.

A 50mm HE shell breaks up into 200+ fragments typically. Notice the large size of the spread of fragment types. Since this is a high velocity weapon (compared to a mortar), the velocity is a major factor in fragmentation delivery. The HE shell already has 'fragmentation' velocity even before it explodes.

The density of forward directed fragments results in a well defined 'forward-killing-cone'. Since this is a precision weapon under most circumstances, this 'cone' can be placed where it is needed.

For direct fire targets such as crewed weapons (many men closely manning a weapon), buildings/bunkers, these fragments would result in lethal effects. Since the HE blast effects are so minimal in this range of calibers, the cone fragmentation and gun velocity/precision effect make up for it.