20mm vs Thin Skinned Targets - A request

[Guest Michael emrys]

Originally posted by tero:

The fragmens from the 20mm shell should be travelling at explosion + shell speed velocity.

Only in the direction of travel.

That should translate to way bigger damage effect than currently is modelled.

As I posted earlier, the splinters of a 20mm shell are small and few, much smaller and fewer than, say, a 75mm shell. To repeat, having one go off inside your body is not at all nice, but having one go off merely nearby is no big threat.

A 20mm shell is tiny, less than an inch in diameter. It can't make a really big bang compared to serious artillery or even a 50-60mm mortar. Unless you are directly hit by a shell, you are not likely to receive a disabling wound from it. Troops that are properly dispersed and using cover properly are not at great risk of getting hit, given the relatively moderate ROF. It's just not the über antipersonnel weapon some people are trying to make it out to be. If it were, every army would have had them all over the front since they were relatively cheap to make.

Michael

[Guest tero]

>While grenade fragments will tend to fly in all directions more or less equally, the 20mm fragments will travel in a more or less elliptical pattern away from the point of impact on the shell's axis of travel.

Elliptical ? From the horizontal or the vertical ? Also, is there any chance the 20mm shell traveling at 900mps (~2500fps) bounce before exploding, making the fragmentation effect more pronounced ? Where there VT settings for the 20mm FLAK shell fuses that would have allowed airbusts ?

>This means a soldier standing between the gun and the impact, or directly to the side of the impact, would have a far lower chance of injury than with a grenade in the same situation.

The trajectory is flat (for all intents and purposes)! The round does NOT fall like a mortar shell. At 900mps the shell will propably travel through anybody between the gun and the impact, making it explode in mid air hurting anybody inside the cone of explosion and fragmentration. Thus the 20mm FLAK is liable to cause multiple horrible and definitely more serious casualties with one round than the MG-42 can.

>The test I sent to Madmatt was very short range (80-300m).

300 meters a bit far for the MG-42.

>I think you are correct that "prediction shots" are not modeled per se. However, there must be some allowance currently made for this in the game or it would be impossible to hit a moving vehicle, for example.

Ever see a unit "forget" it was targeting a unit before it went out of LOS ? When the unit emerges again the targeting starts from scratch. The lack of short (and long) term memory for the TacAI is one of the bigger issues in general.

>I would think that true prediction firing as you suggest would require a major overhaul of the TacAI and gunnery models in the game and is probably not feasible for the near future, at least.

I think when the memory span for the TacAI gets overhauled this will be corrected to a certain degree.

>Not really. 20mm shells do not receive tree burst effects in the game (only artillery does this AFAIK).

Technically FLAK is artillery so it should get tree bursts as the shell is HE and it does explode.

>Nevertheless, 20mm is more effective than MG42 vs. stationary targets whether they are in cover or not, especially at long ranges.

No argument there.

[Guest tero]

>The key here is in the rate of fire and distance between men in a squad being engaged.

That argument is valid only to the extreme effective range of MG-42. The effective range of a 20mm FLAK is at least double or tripple the effective range of the MG-42. When the distance gets bigger linearly the effect of the MG-42 drops exponentially while the 20mm keeps on kicking serious butt.

>A MG42 can spit out literally hundreds of rounds in a few seconds (based on between 1200-1500 rounds per minute cyclic rate) while the 20mm is only getting at best a little under 1/2 that amount (assuming between 350-700 rpm and IIRC they aren't firing anywhere near that rate in the game for the most part).

IIRC the practical ROF for the 20mm FLAK is 120 or so RPM.

>While the cannon rounds explode it is doubtful that a single rounds explosion would injure more than one man in a squad using proper combat spread.

Please define proper combat spread.

By this logic a squad in the open would be safer than a squad in cover of a house or trees. Which is not very realistic since the squad in the open would be more exposed to accurately aimed fire. And the squad in the cover would be subject to collateral damage from high speed fragments AND debris. I have a hunch 2 20mm HE rounds (counted from practical ROF) per second puts out more fragments than 25 7.92 slugs per second (counted from the cyclic, NOT the practical ROF which as it should be).

Kinetic effects as well as HE effects need to be calculated in to calculate the effects.

The 50cal was a mean mother so why should the 20mm FLAK get the shaft ?

The comparison should be made between the 50cal and the 20mm FLAK, not the MG-42 and the 20mm FLAK.

>Obviously a cannon shell will cause greater damage to the target but the end result in the game is same, an incapcitated man.

"Men" in case of the 20mm FLAK.

>So, all things being equal, in the same stretch of time the MG42 is able throw

out at least twice the firepower and as such cover a greater area with lead with relatively the same effect as the cannon when a man is hit.

All things are not equal in this case. For example a single round from a 20mm is more liable to cause multiple casualties. How many 7.92mm slugs are comparable to a 20mm shell ?

As you pointed out the distance is a main factor in these calculations. At 30 meters there is no doubt the MG-42 is the winner but what about at 700 meters ?

>A more fair test would be to compare the results based on similar amounts of rounds fired.

I think that kind of test would not be statistically representative. For one the fragment count from a single shell should be counted as a factor.

>The test above shows a MG42 getting 110% more hits than the slower firing 20mm yet what no one is looking at is that both weapons are shredding the squads apart.

Anybody had time to compare the 50cal and the 20mm FLAK ?

>The direct comparission is apples and oranges as you are taking two different

weapon designs with two different intended methods of employment into an artificial situation that greatly favors the overwhelming rate of fire of the Mg42.

A more valid comparison would be made between the 50cal and the 20mm FLAK.

>Much of the Close Assualt issue is peoples incorrect perception of what is happening. True close assaults in the game only occur within 10 meters of the target. Get that close and see how successful your assaults are. At longer ranges than that your squads are trying to do what they can with grenades

which are not very accurate themselves and need a decent bit of luck to explode near enough (or under or into) a vehcile to cause suffecient damage to take it out.

Luck should not be that big a factor when you are aiming and throwing baseball-like objects at an opening of (roughly) 2 meters by 4 meters from 20 odd meters. It is difficult but not very hard if you are not suppressed.

Hand grenades have essentially timed fuses so could there be a number of hand grenade explosions that are modelled as air bursts ?

[Guest tero]

>Only in the direction of travel.

Yes.

>As I posted earlier, the splinters of a 20mm shell are small and few

How small and how few exactly ? At 900mps + the explosion acceleration the fragment, which was designed to rip apart metal frames of aircraft, was VERY effective against soft targets.

>, much smaller and fewer than, say, a 75mm shell.

I am not contesting that.

>To repeat, having one go off inside your body is not at all nice, but having one go off merely nearby is no big threat.

Not unless you are standing behind a guy who gets hit by one or more as there are 2 shells per second coming your way. And chances are at of 900 mps the shell will pass through you (or the guy in front of you) and explode in mid air making it in effect an airburst thus making the fragmentation effect worse than a ground impact would.

>A 20mm shell is tiny, less than an inch in diameter.

Around .70 cal if you want to compare it with the 50 cal.

>It can't make a really big bang compared to serious artillery or even a 50-60mm mortar.

But it does make a swift serious of bangs at 120rpm. And it is able to go through obstacles better than the said 50-60mm mortar shell traveling at a fraction of its velocity.

>Unless you are directly hit by a shell, you are not likely to receive a disabling wound from it.

Think again. We are talking about 2 shells a second here. If you get targeted chances are that

a) you will not have time to duck before the shells arrive if you get caught by surprise (as they travel at near sonic velocity)

if you get pinned down there is no way to escape unless they switch targets, there is a jam or they fumble with the reload magazine long enough you are able to get behind cover

c) which may turn out to be as good as carboard and if they saw you get into the cover they might turn the cover to Swiss cheese

>Troops that are properly dispersed and using cover properly are not at great risk of getting hit, given the relatively moderate ROF.

I disagree. There is nothing moderate about the ROF, when you are actually in the receiving end.

>It's just not the über antipersonnel weapon some people are trying to make it out to be.

No. But if used properly it could shread a platoon to pieces in seconds. Remember, it can hose down as well as any MG can, at longer ranges.

>If it were, every army would have had them all over the front since they were relatively

cheap to make.

The Allies had their 50cal, which is comparable to this weapon in terms of fire power.

[Vanir]

Tero, I think you're arguing mostly for the sake of arguing, but I'll bite anyway.

Elliptical ? From the horizontal or the vertical ?

In the direction of travel, as Michael and I both stated. In any case, the point is it's not omni-directional as would be with a hand grenade or mortar.

Also, is there any chance the 20mm shell traveling at 900mps (~2500fps) bounce before exploding, making the fragmentation effect more pronounced ? Where there VT settings for the 20mm FLAK shell fuses that would have allowed airbusts ?

Bouncing 20mm shells? They certainly weren't designed to bounce. AFAIK, 20mm shells did not have VT fuses. If you find otherwise please post it.

The trajectory is flat (for all intents and purposes)! The round does NOT fall like a mortar shell. At 900mps the shell will propably travel through anybody between the gun and the impact, making it explode in mid air hurting anybody inside the cone of explosion and fragmentration. Thus the 20mm FLAK is liable to cause multiple horrible and definitely more serious casualties with one round than the MG-42 can.

I don't know where you get the idea that the shell will explode "in mid air". You repeat this several times in your posts and it is baseless. Unless the shell had some type of fuse it would only explode upon contact with a solid object (the ground, a wall, a vehicle, but probably not a human body I would think).

300 meters a bit far for the MG-42.

You took that figure out of context. I actually said 80-300m. Most of it at well less than 300.

Ever see a unit "forget" it was targeting a unit before it went out of LOS ? When the unit emerges again the targeting starts from scratch. The lack of short (and long) term memory for the TacAI is one of the bigger issues in general.

The fact that the AI has no memory causes problems sometimes, but that's not going to change any time soon and is a separate topic anyway.

Technically FLAK is artillery so it should get tree bursts as the shell is HE and it does explode.

That's silly. No direct fire weapon gets tree bursts including real artillery like the Wespe and Hummel. I seriously doubt the 20mm shell has enough explosive charge to cause any significant tree burst anyway.

That argument is valid only to the extreme effective range of MG-42. The effective range of a 20mm FLAK is at least double or tripple the effective range of the MG-42. When the distance gets bigger linearly the effect of the MG-42 drops exponentially while the 20mm keeps on kicking serious butt.

True, which is the way it is in the game.

By this logic a squad in the open would be safer than a squad in cover of a house or trees. Which is not very realistic since the squad in the open would be more exposed to accurately aimed fire. And the squad in the cover would be subject to collateral damage from high speed fragments AND debris.

You say that a squad being more safe in the open is unrealistic then defeat your own argument by pointing out the damage from fragments and debris while in cover.

I have a hunch 2 20mm HE rounds (counted from practical ROF) per second puts out more fragments than 25 7.92 slugs per second (counted from the cyclic, NOT the practical ROF which as it should be).

This ignores the fact that if you shoot at something 25 times your much more likely to hit it than if you shoot at it twice. Yes, MG42 bullets do not explode, but then we get into the "how many MG42 bullets equals one 20mm shell" question that nobody knows the answer to.

Kinetic effects as well as HE effects need to be calculated in to calculate the effects.

The 50cal was a mean mother so why should the 20mm FLAK get the shaft ?

The comparison should be made between the 50cal and the 20mm FLAK, not the MG-42 and the 20mm FLAK.

First of all, the MG42 is a meaner mother vs infantry than the 50 cal. at most ranges seen in the game. Look at the FP ratings in the unit stats. The MG42 is higher than the 50 cal. out to about 600m or so. Comparing the 20mm to the .50 cal instead of the MG42 is pointless. If you already know how well the MG42 stacks up you can look at the FP ratings and see how the 50 cal. compares. It will perform somewhat worse than the MG42 at less than about 600, and somewhat better beyond. And yes, I have tested the 50 cal. vs the 20mm as well to verify this.

All things are not equal in this case. For example a single round from a 20mm is more liable to cause multiple casualties. How many 7.92mm slugs are comparable to a 20mm shell ?

Good question. Let us know when you have the answer.

How small and how few exactly ? At 900mps + the explosion acceleration the fragment, which was designed to rip apart metal frames of aircraft, was VERY effective against soft targets.

How small and how few indeed. Do you know? I don't know either, but common sense would suggest that an object less than 1 inch in diameter could not possibly create anything much larger than a few millimeters and not many of them. There just isn't enough material there.

Not unless you are standing behind a guy who gets hit by one or more as there are 2 shells per second coming your way. And chances are at of 900 mps the shell will pass through you (or the guy in front of you) and explode in mid air making it in effect an airburst thus making the fragmentation effect worse than a ground impact would.

There you go with the airburst thing again.

The shell probably would go through a man but so would a 50 cal. bullet. MG42 could as well, but not as frequently.

Also, the muzzle velocity of the 20mm is 780 m/sec not 900.

The Allies had their 50cal, which is comparable to this weapon in terms of fire power.

First you say the 20mm is artillery, then you say it's comparable to the 50 cal. MG!? The 50 cal. has more in common with the MG42 than the 20mm. The 20mm is a cannon. The 50 cal. and the MG42 are machine guns.

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What a bunch of horsecrap. -Steve

[This message has been edited by Vanir (edited 02-19-2001).]

[Guest tero]

>Tero, I think you're arguing mostly for the sake of arguing, but I'll bite anyway.

I prefer to use the term debate. Too many debates degenerate into arguments around here though.

>In the direction of travel, as Michael and I both stated. In any case, the point is it's not omni-directional as would be with a hand grenade or mortar.

The base of the ellipse is at the detonation. Got it.

>Bouncing 20mm shells? They certainly weren't designed to bounce. AFAIK, 20mm shells did not have VT fuses. If you find otherwise please post it.

I'm on it.

The only positive proof of 20mm FLAK airbusts (VT or proximity fuses) I have is a scene from the movie English Patient but that is by no means conclusive evidence.

However, in Blitzkrieg by Deighton there is a grarphic representation of generic FLAK effective ceilings and there there is there is a line for longest setting of time fuse. Since there is nothing mentioned about light FLAK only firing impact fuse rounds I take it there were VT or proximity fuses for them too. There were selfdestruct fuses for other German ordnance so to have one for the 20mm FLAK would not be that unheard of.

>I don't know where you get the idea that the shell will explode "in mid air".

At 900 meters per second the 20mm HE rounds is in and out of the body before it detonates. That means the ellipse of schrapnels spreads behind the first victim.

>You repeat this several times in your posts and it is baseless. Unless the shell had some type of fuse it would only explode upon contact with a solid object.

If we assume a human bone is a solid object in most cases the kinetic energy of the 20mm round WILL drive it out of the body before it has time to detonate. It must be remember that the 20mm HE shell was designed to pierce metal skins of aircraft so it was delayed so as not to explode on impact with the outer skin of the aircraft. With a slight delay it would penetrate before exploding causing more damage to the controls of the aircraft. Unless it had a VT/proximity fuse of course.

>You took that figure out of context. I actually said 80-300m. Most of it at well less than 300.

I did not take it out of context. What I meant was to convey that the test is somewhat biased towards the MG-42 with those parameters.

>The fact that the AI has no memory causes problems sometimes, but that's not going to change any time soon and is a separate topic anyway.

Agreed.

>That's silly. No direct fire weapon gets tree bursts including real artillery like the Wespe and Hummel.

Which is not realistically accurate.

>I seriously doubt the 20mm shell has enough explosive charge to cause any significant tree burst anyway.

Depends what is considered significant. I soldier blinded by splinters is as ineffective as a soldier who has lost his arms.

>You say that a squad being more safe in the open is unrealistic then defeat your own argument by pointing out the damage from fragments and debris while in cover.

No. If you read me thoroughly a squad in the open is subject to ACCURATELY aimed fire while a squad in a cover is subject to, for lack of better term, area fire effects. Of the two I deem the aimed fire to be more perilous to life and limb.

>You believe the cyclic ROF is more important than the practical ROF when determining effects in real combat. Interesting.

Please read the post again. It was MadMatt who gave the cyclic rate as an example, not me. I was just pointing out that per second the number of rounds is incomparable but when translated into schrapnels the 20mm is not that "ineffective" when it comes to weight of fire at any given timeperiod in seconds. By using the cyclic rate MadMatt gave I tried to emphasize that point. When the practical rate of fire is used in the calculation MG-42 loses its feathers.

>First of all, the MG42 is a meaner mother vs infantry than the 50 cal. at most ranges seen in the game. Look at the FP ratings in the unit stats. The MG42 is higher than the 50 cal. out to about 600m or so. Comparing the 20mm to the .50 cal instead of the MG42 is pointless.

How so ? Comparing the 20mm FLAK to the MG-42 is more inaccurate. The 50cal and the 20mm FLAK are not that dissimilar in their employment to make them be totally incomparable.

>If you already know how well the MG42 stacks up you can look at the FP ratings and see how

the 50 cal. compares.

That is not quite the same now is it.

>It will perform somewhat worse then the MG42 at less than about 600, and somewhat better beyond. And yes, I have tested the 50 cal. vs the 20mm as well to verify this.

So what was the conclusion ? I'm interested to see a similar table as was seen on the MG-42 vs 20mm data.

>How small and how few indeed. Do you know? I don't know either, but common sense would suggest that an object less than 1 inch in diameter could not possibly create anything much larger than a few millimeters and not many of them. There just isn't enough material there.

Diameter does not determine the size of the shell alone. You have to take into account the lenght of the shell as well. It is not a 20mm disk they are firing after all.

And as you pointed out yourself all of it is going pretty much in the same direction emphasizing the effect of the detonation.

>There you go with the airburst thing again.

Just trying to convince people that a shell doing 900 meters per second does not lose impetus within the few inches that make the human body. It WILL go through and through and most propably detonate outside the body. Or splatter somebody all over the scenery AND cause further wounds to anybody unfortunate to be near enough and in the path of the traveling shcrapnel.

>The shell probably would go through a man but so would a 50 cal. bullet.

The only difference is the 50cal slug does not exlode.

>MG42 could as well, but not as frequently.

If the people we standing were close together or they are within 30 meters of the MG. And it will not be able to do that over extended distances.

>Also, the muzzle velocity of the 20mm is 780 m/sec not 900.

According to what source. The Blitzkrieg by Deighton gives says the muzzle velocity of FLAK 30 was 900 meters per second. So do a few other sources I have on FLAK38.

>First you say the 20mm is artillery, then you say it's comparable to the 50 cal. MG!? The 50 cal. has more in common with the MG42 than the 20mm. The 20mm is a cannon. The 50 cal. and the MG42 are machine guns.

The 20mm FLAK is comparable to the 50cal in caliber and fire power way better than the MG-42 is. The 50cal is 12,7mm and the 20mm FLAK is, well, 20mm. The only difference is the 50cal does not come with HE. But the kinetic effects should be similar.

[Guest Germanboy]

Originally posted by Vanir:

There you go with the airburst thing again.

Much as people may dislike the idea that AA guns have MT fuses, unfortunately reality tells us otherwise. We have been here before about 88s. There is a very simple reason for this. The primary purpose of these guns was/is air defense. Now if you want to defend a place against air attacks, it is a very bad idea to have missing rounds come down in the vincinity with contact fuses and go boom on impact, destroying the property you just defended against the air attack. You want the rounds to explode a high way above your head. Even the shrapnell poses a problem and can hurt people.

Modern 20mm solves that problem (largely) by having the fuse set to 1,600m distance, with no alteration possible. The 88 had a Zuenderstellgeraet (Fuse setting apparatus) fixed to the gun, which I believe was used to set the MT fuse (if somebody knows for sure, please let me know). How 20mm did it then I don't know (whether the setting was fixed or variable, probably fixed), but the gun must have been capable of achieving low-lying airbursts, if only at a fixed distance. So tero has a point to go on about air-bursts.

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Andreas

Der Kessel

Home of „Die Sturmgruppe“; Scenario Design Group for Combat Mission.

[Guest Germanboy]

Originally posted by tero:

>It's just not the über antipersonnel weapon some people are trying to make it out to be.

>If it were, every army would have had them all over the front since they were relatively

cheap to make.

tero - I know you did not say it, but I can't find who said it.

Currently in service with 20mm autocannon:

German APC Marder (variant)

German PSW Luchs

German light tank Wiesel (variant)

The Wiesel (front 20mm, rear TOW ATGM)

With similar size cannon:

UK APC Warrior (variant)

US APC Bradley (variant)

Russia - various BMPs (or whatever they are called)

France - must have one

Brazil - wheeled PSW thingy

Someone somewhere must think these things are darn effective as organic fire support for the PBI

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Andreas

Der Kessel

Home of „Die Sturmgruppe“; Scenario Design Group for Combat Mission.

[This message has been edited by Germanboy (edited 02-19-2001).]

[PawBroon]

Originally posted by Germanboy:

Currently in service with 20mm autocannon:

France - must have one

Right.

It's called an AMX 10P.

IFV with a squad in it.

Here goes:

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You are not Obsessive-CMpulsive, you are Allied-Retentive.

Mark IV

[Vanir]

Thanks for the info Germanboy.

One point. If the fuses were fixed it would do no good against targets at a different distance (obviously). Sinse the 20mm was an anti-aircraft gun it is probably safe to assume that it's fuses were set at a distance much farther than you would see it engaging infantry at in a typical game of CM.

Something that I think has been lost in this is that the original debate was not over the 20mm firepower, but its accuracy vs. running infantry. To illustrate this I did another test. For Tero's benefit I did this one with 50 cals. Each test was 3 regular quality M2s/20mm firing at a platoon of elite infantry stationary in woods at 300m. For each test I let them fire for 3 turns and I ran the test 10 times for a total of 30 turns of carnage. Results:

Mean Mother M2: 25 casualties.

20mm: 111 casualties.

That's 344% more casualties for the 20mm.

So the real question isn't whether the 20mm is more powerful than the M2 or the MG42. It is. Hell, it's way more powerful. The question is how accurate is it vs running infantry vs MGs, especially at short ranges where the MGs much higher ROF and smaller size comes into play.

One lesson seems to be that if you find yourself under fire from a MG you should seek cover and hunker down until other units can suppress or kill it. If it's a 20mm shooting at you haul ass out of LOS or charge it head on right away. Whatever you do don't let it sit there and pound on your stationary troops for several turns.

Seems logical to me.

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What a bunch of horsecrap. -Steve

[Guest tero]

>tero - I know you did not say it, but I can't find who said it.

Contrary to common beliefs trolls have thick skins.

There seems to be some unclarity as to the doctrinal subleties involving light AAA and its use.

>Someone somewhere must think these things are darn effective as organic fire support for the PBI.

Wait until Pentagon realizes the cost/effect ratio of these things ! Then the Americans will say the 20mm autocannon is the best there was and is.

[Guest tero]

>One point. If the fuses were fixed it would do no good against targets at a different distance (obviously). Sinse the 20mm was an anti-aircraft gun it is probably safe to assume that it's fuses were set at a distance much farther than you would see it engaging infantry at in a typical game of CM.

I believe there is a contact fuse AND a timed selfdestruct ... device. At 900 mps the 1600 m limit is reached in just under 2 seconds.

>Something that I think has been lost in this is that the original debate was not over the 20mm firepower, but its accuracy vs. running infantry.

That tends to happen when the debate twists around the subject.

>That's 344% more casualties for the 20mm.

That is impressive. And expected. Can you do a comparative test againts HT's and trucks ? In my experience the 20mm FLAK is quite effective against infantry, static or running, in cover or in the open, regarless of range. But the 50cal SEEMS to take the cake when it comes to firing againts vehicles. Is there a marked difference between infantry and vehicle 50cals ?

My doubts are mostly based on observations on turret mounted M2's. Do they get benefits from stabilizers (especially if the main gun is engageing the target at the same time) when they should not ?