CAS in CM2

[Erwin]

I know this has been discussed b4, but is there a safe/appropriate distance one needs to keep friendlies from the outer ring of a CAS area target?

In the fun "Road to Nijmegan" I just had bombs dropped on friendlies that were 280 meters+ from the edge of an area fire circle. Considering the small CN2 maps, that seems a bit naff.

Conversely however, despite 10+ meter holes a few meters away from the troops, only 2 were KIA/WIA and a couple other went "yellow". That seems surprisingly ineffective, and I understand now why the CAS (and even heavy arty) seems rather ineffective vs enemy troops.

Took 20-30 88mm HE plus a couple dozen 81mm to KO one dam ATG.

Any advice on how to use CAS or HE better?

[SlowMotion]

I would assume that people a few meters from explosion which creates a 10 meter crater would be in pretty bad shape.

[akd]

Depends hugely on whether you are giving the aircraft point targets or telling them to seek out targets on their own.

[Erwin]

Yes, I was giving the CAS area fire, but shouldn't they make some effort to stay in the circle?

280-300 meters away from the EDGE of that circle seems a looong way off esp on the average CM2 map.

And as I said I have been amazed at how little damage can be caused by what must be a huge explosion only a few meters away.

So, my original question was, and still is, IF this is realistic CAS behavior, what is a safe distance away from a target circle?

[womble]

I would assume that people a few meters from explosion which creates a 10 meter crater would be in pretty bad shape.

You'd think so, wouldn't you. I recently hit an ATG position, in the edges of some Heavy Forest with a point 150mm strike (2 tubes, IIRC, about 12 rounds). After the shoot ended, there were half a dozen craters in the AS either side of the one where the 6lber was. Two trees in the AS where the gun sat had gone (which I'd never seen before; I've seen foliage stripped, sure, but the entire trunk structure had been erased), yet there were two survivors who killed another tank with their still-functioning piece. Tough hombres.

[Vanir Ausf B]

For an unguided 500 lb bomb the present-day US Air Force considers anything within 245 meters of friendly forces to be "danger close". 280 meters away in WW2 would probably have been called "flipping a coin".

[SlowMotion]

That >200 meter distance is for how far shell fragments are dangerous.

A fragment could fly that far and hit someone lethally.

But just few meters away there's also the pressure which hits everything nearby, not like the pieces of metal which may hit or not.

[Baneman]

I'm not sure that CM2 models a "lethal pressure radius".

I think it should, but it may be too technically difficult to do eg. having to take into account walls and other objects on the fly etc.

I think this because I've seen 81mm mortars literally drop at the feet of a running man and he is unscathed ( possibly because all the tracked fragments fly away from where he is ).

Also, although I have no proof, ( and I don't have an early install to check ), I have a sneaking suspicion that HE lethality overall has been toned down since CMBN 1.0 - also based on observed remarkable ATG and similar survival after horrendous pounding.

[Erwin]

I agree that large caliber HE seems to have much less effect than would be expected - from blast FX alone. Enemies seem to not only survive but recover and fight quickly after being very close to a large explosion.

Re CAS, would it be reasonable (re CM2 tactics which are often different from RL tactics) to use the "Heavy" CAS stuff first when friendlies are more than (say) 350 meters from the target radius? There must be some sort of "safe" distances that would be used?

[slysniper]

Also, although I have no proof, ( and I don't have an early install to check ), I have a sneaking suspicion that HE lethality overall has been toned down since CMBN 1.0 - also based on observed remarkable ATG and similar survival after horrendous pounding.

That is a statement that is not hard to see if you have played the game enough. For sure arty has been adjusted. accuracy is not as tight and effect is weaker.

As to the original post. There has been post before on this subject that you should pull up that address your question.

As for game play, I have learned from them post. avoid area fire if at all possible. If you can use point targets you will find your CAS missions will normally always be on target and you will not see that type of problem.

After having a similar event as you I have learned it is worth getting someone in place to make a point target location and give my planes a real chance at doing some real damage to the enemy.

[Vanir Ausf B]

That is a statement that is not hard to see if you have played the game enough. For sure arty has been adjusted. accuracy is not as tight and effect is weaker.

I have been wondering about this. If true it would be a good thing since I thought HE of all types was too powerful early in CMBN, albeit mostly against prone soldiers specifically rather than standing up. Odd the BFC would make such a change without telling anyone.

[Fizou]

Remember that because the soldiers are closer togerher than in real life (more bunching up etc.) the HE effect is scaled down to mitigate this. So with this abstraction in mind I think things are working as intended (a driect hit might not be exactly a direct hit etc).

[Michael Emrys]

I'm not sure that CM2 models a "lethal pressure radius".

I think it should, but it may be too technically difficult to do eg. having to take into account walls and other objects on the fly etc.

There may not be that much to model anyway. I read somewhere a couple of years ago that blast and overpressure effects have been greatly exaggerated in popular accounts. Men did die of it, but it was rare. Someone sifted through battlefield medical reports and found that the vast majority of wounds, including fatal ones, were caused by fragments not by blast.

Michael

[SlowMotion]

If you think about the OP case: bomb explosion that creates a 10m wide crater. Nobody is going to be right next to such explosion and after a few seconds be like nothing had happened.

[Erwin]

"...I have learned it is worth getting someone in place to make a point target location and give my planes a real chance at doing some real damage to the enemy."

Agreed that is the ideal. But, with a 13 minute wait in CM2 WW2 ("Road to Nijmegan"), it's hard to take the time to recon properly and then have a valuable FO sit spotting and waiting for that much time. (He's more valuable bringing down arty in a much shorter time.)

I generally area fire the CAS as far away as possible at the start as otherwise one may not have time to use it at all. I wuz hoping there was a really good way of using CAS that I didn't know about. ;/

[A Canadian Cat]

As for game play, I have learned from them post. avoid area fire if at all possible. If you can use point targets you will find your CAS missions will normally always be on target and you will not see that type of problem.

I have had good success using area fire for CAS missions recently. In Monty's Butchers, White Mannor and not too long ago in a QB. I have never used the point target option - I would be afraid that by the time the mission started the target would be gone.

In the case of Monty's Butchers I called it in late in the game and I had friendlies about 300m of the edge of the target circle. I figured that would be far enough. There was only one tank and several squads there most of my force was 500m and more away. That mission was a success - took out one Panther.

In the case of White Mannor I set the CAS missions at the game start and my forces never got closer than 500m away from the area. That one sure seemed to work well - game is still going so not totally sure. I saw the planes strafing many times and one AT gun that I did not take out myself was first spotted destroyed by my approaching infantry. I am all in favour of letting the pilots choose their targets.

In the case of the QB again mission was set at start up and my guys were never very close at all. I have to admit frustration that the pilot failed to strafe the open top M10s of my opponent but he sure did chew up my opponents infantry and keep them from moving into some key ground on my approach to the objective.

[Vanir Ausf B]

I have been wondering about this. If true it would be a good thing since I thought HE of all types was too powerful early in CMBN, albeit mostly against prone soldiers specifically rather than standing up. Odd the BFC would make such a change without telling anyone.

Curiosity got the better of me, as it tends to do. I re-ran the US 60mm mortar lethality tests I did under CMBN v1.10. In those tests I came up with I casualty per 2.1 rounds in the first test, 1 casualty per 2.26 rounds in the second test.

http://www.battlefront.com/community/showpost.php?p=1400299&postcount=187

http://www.battlefront.com/community/showpost.php?p=1400328&postcount=192

Now in CMBN v2.12 I get I got 1 casualty per 2.25 rounds (85 casualties, 192 rounds counted).

If there has been any change it isn't showing up here.

[John Kettler]

Erwin,

Skip to Conclusions if not interested in meat of explanation of what befell your men and why.

1.

Here are the modern MSDs (Minimum Safe Distances) for Indirect fire. The link also explains how MSDs are calculated. Table is for observed, adjusted fires.

http://www.fas.org/man/dod-101/sys/land/indirect.htm

2.

Here are the MSDs for aerial munitions of the Vietnam War. For Protected troops, the MSD of a MK 81 250 lb Low Drag (better fins and aerodynamics than WW II bomb) is 216 meters. For Unprotected troops, the MSD is 620 meters.

http://www.cc.gatech.edu/~tpilsch/AirOps/munitions.html

3.

I think, too, you'll find the air attack results (and scary miss distances) for recent aerial warfare instructive and disturbing. I did. Even modern weapons can generate significant to dramatic miss distances. The Myth of the Precision Bombing.

http://defenseissues.wordpress.com/2013/01/19/the-myth-of-the-precision-bombing/

4.

I've been hammering away on the whole FO own-location issue for years, but it bears repeating. A U.S. Army study in the early 1980s found that the average FO was 300 meters from where he thought he was! That error cascaded through the whole fire support chain. Over North Vietnam, where MSDs were not even an issue, by the end of the war, here's what F-105 CEPs were. "Did USAF Technology Fail in Vietnam?"

http://www.airpower.maxwell.af.mil/airchronicles/apj/apj98/spr98/werrell.html

"The advantage of the guided bombs is starkly revealed when compared with the F-105’ s work in the same areas (Route Packages VIA and VIB). The F-105s achieved a circular error probable (CEP) of 447 feet and 5.5 percent direct hits during the end of Rolling Thunder."

5.

Returning to WW II, in combat accuracy comparisons for dive bombing, the CEP of three squadrons of SBD-5 Dauntless dive bombers, arguably one of the best dive bombers ever, was 175 feet/53.3 meters, in the face of optically directed AAA, against static point targets as small as 50 feet/15 meters across (Tillman's book Corsair, no pagination in sample online). Seen any 50'/15 meter long tanks lately? Mind, this is the most accurate bombing mode. It's much worse for a low level pass. JasonC will happily show you how ineffective WW II CAS aircraft were in attacking armor with bombs and rockets, and we're talking squadrons of planes in some of the strikes.

Recap

So, to recap. The FO doesn't really know where he is. If the pilot is accurately directed (a big if) to the target, then, at best, only half the bombs dropped, in a dive bombing attack while under fire, will land within 175'/53.3 meters of the intended target. Rudel himself characterized speed as poison when it came to locating and attacking tanks, and he was operating over the plains of the Ukraine! In France, Belgium, Holland and elsewhere, just finding the target's an accomplishment, let alone hitting it.

Conclusions

In sum, while it may be galling, what happened to you seems entirely reasonable, and BFC's probably being most generous in treating CAS delivery accuracies the way it does. From everything I can tell, you were much too close, even by Vietnam War standards. You were 280 meters away from the edge of a target area well inside the MSD for the munition used. While I doubt BFC is that brutal, and 'Nam era 250 lb bombs were considerably more potent than WW II ones were, I think it should give you some idea how lucky you were casualties weren't even higher. "Friendly fire isn't," and this is particularly true when dropping 250-lb bombs near friendlies. The bomb that clobbered your guys did so (presuming bomb landed just inside boundary of area target) from ~ half the casualty radius against Unprotected troops.

Regards,

John Kettler

[Erwin]

That was interesting, John.

The stats from your link re blast radius are the following:

100 meters - M203 & 40mm

200 meters- 60mm mortars

300 meters - 81mm

400 meters - 105 mm

500 meters - 155 mm/naval gunfire

MK 81 LD GP bomb 250 215 m 620 m

MK 82 LD GP bomb 500 225 m 700 m

MK 82 HD GP bomb 500 170 m 700 m

So if (250lb-500lb) WW2 bombs were equivalent one needs to be at least 215 meters from the blast edge and to be completely safe, 620-700 meters. That is usually impossible on the CM maps most usually seen. But, as a rule of thumb, one should be unlucky to get hurt of one is more than 250 meters from the center.

However, my original question was NOT about blast radius but ACCURACY of the pilot dropping the bomb, when one has designated the TARGET AREA EDGE to be over 250 meters away from friendly troops. All I want to know is what is the safe distance from a targeted zone. If the pilot was accurate and the radius of the target area was (say) 100 meters, then the friendly would be a pretty "safe" 350 meters away.

The question is why does the pilot see (and bomb) friendlies 300 meters outside the zone but not the enemy that is inside the zone.

If CAS was this bad in RL, I would wonder why it was ever called in.

[Vanir Ausf B]

During Operation Desert Storm, at most 60% of bombs have achieved hits on targets, and many misses were off by hundreds of meters. In fact, success rate could have been as low as 41%.

..................

[Baneman]

Well, I recently had cause to call in some air support ( also in the Nijmegen campaign ).

1 minute before the plane was due, my whole army hid. The CAS was offtarget and closer to me than the enemy, but I got away unscathed - I reasoned that the less he could see of mine, the more likely he was to see "them"

[slysniper]

Curiosity got the better of me, as it tends to do. I re-ran the US 60mm mortar lethality tests I did under CMBN v1.10. In those tests I came up with I casualty per 2.1 rounds in the first test, 1 casualty per 2.26 rounds in the second test.

http://www.battlefront.com/community/showpost.php?p=1400299&postcount=187

http://www.battlefront.com/community/showpost.php?p=1400328&postcount=192

Now in CMBN v2.12 I get I got 1 casualty per 2.25 rounds (85 casualties, 192 rounds counted).

If there has been any change it isn't showing up here.

Interesting

So maybe there has been no changes.

But since I have not tested 1.0 to 2.12, I should say nothing.

Or maybe what I am seeing is players have learned to deal with arty better, I sure know I have. So maybe the affects of arty is not as bad as it once was just for the shear fact players have learned how to avoid it.

[John Kettler]

Erwin,

Am glad you found it interesting, but I think you missed a key part of my points. I think you misunderstood what I was saying about target posture. "Protected" means in substantial cover (foxhole, trench, behind big rocks, sandbags, that sort of thing; cover must be able to withstand a rifle bullet strike without being penetrated) and prone. By contrast, "Unprotected" is for a standing man on open ground. The MSD is based on the break point in which a fragment no longer has the ability to pierce the skin, since it's velocity is insufficient to do so.

Given the above, I believe you need a new rule of thumb, because your current one is based on a fundamental misunderstanding of what's being said in the MSD table. Now, lets look at the MSD issue from the perspective of experts in explosives.

Understanding MSD

The rule of thumb for standoff distance is 50 m for every 0.5 kg of TNT equivalent. This is from The Preparatory Manual of Explosives, Ledgard, p. 93.

Per Standard Ordnance Items Catalogue 1944, Volume 3, p. 573, the fill on a standard 250-pound bomb is 124.9 pounds of TNT or 56.8 kg of TNT. 56.8 x 2 = 113.6 0.5 kg equivalents. 113.6 x 50 m = 5680 m! Obviously, the military MSDs are far less restrictive than that, but it does serve to bound the problem. By contrast, a vanilla 105 mm howitzer shell, using the same calculation methods, has a minuscule 2.8 pounds of TNT fill = 1.27 kg of TNT x 2 = 2.54 0.5 kg TNT equivalents. 2.54. x 50 m = MSD of 127 m. 2.2% of the MSD for the 250-pound bomb!

As I've clearly shown, the only time it's reasonable to have own troops 250 meters away from the edge of the target area, with a 250-pound bomb coming down. is when they're Protected as defined above, i.e., in hard cover. Understand that the pilot is navigating with a map quadrant on his knee--while flying the plane, too. There's no HUD, no autopilot, no inertial nav, no GPS. He's flying to a target grid. He hopes friendlies will have ID panels out, but can't count on it. He's hoping for an "Enemy over there" marker of some sort. ID smoke may or may not be where it's supposed to be, and wind may simply blow it away. Friendlies may or may not be where they were when he was briefed. If there's a landmark (often there isn't), battlefield obscuration or weather may blur or hide it. These are but a portion of the issues interfering with accurate delivery. Pilot reaction time may be off a bit, a bomb fin may be bent, the bomb snags momentarily on the rack and drops slightly late. Excerpt from from Air Munitions Data follows. Weapons Safe Minimum Distances.

http://web.archive.org/web/20061030011854/http://www.gruntonline.com/US_Forces/US_Artillery/arty13d.htm

"The following table shows the minimum safe distances from unprotected troops for delivery of ordnance. The distances listed represent the range at which a fragment from the particular munition will not penetrate the skin of an individual standing in an open field. The figures are based on a probability of kill of zero (Pk=0). They do not take into account aiming errors, pattern length, or pattern dispersions. The distances are from the actual point of impact. For the BLU-3/B and the BLU-26/59/B, the figure represents the actual point of impact of a single bomblet from the CBU dispenser. The safe distance for rockets is measured from the actual point of impact for a single 2.75" FFAR.

The table also shows the minimum safe distances from protected troops that various types of ordnance may be delivered. The distances offer reasonable casualty-free risk for troops in armored vehicles, bunkers, trenches, or fox holes who are shielded from the point of detonation. They are based on 150% expected delivery accuracy, 200% lethal radius, 60 meters target identification error for high angle delivery, and 30 meters for low angle delivery."

Note well the part about what's not being covered in calculating those tables.

Why do CAS? Here's why!

Instantaneous, overwhelming firepower at and around the point of impact when the bomb goes off, with enormous areal coverage. In terms of putting HE on the target, it would take 45 105 mm shells, delivered simultaneously on a common point, to match it. Doing that would require 3.75 battalion volleys, based on an 18-gun SP artillery battalion.

There's no waiting for FDC to crunch the numbers, no wait for the spotting round alert, no spotting round adjustment or adjustments to sweat out. If you've got the CAS bird, other factors permit, and the CAS aircraft has a bomb, in rolls the P-47 or what have you, down comes the bomb. Wham! A crater 32 m W x 10 m deep appears in an instant at the point of impact. The soil and rocks there go fountaining outward and upward. The blast wave destroys various things out to defined radii which vary based on structure hardness. Protected troops out to a certain distance, modified by various environmental factors, will suffer blast lung or other internal injuries and die or be severely injured. Further out, they may be knocked unconscious, stunned and deafened temporarily or permanently. Blast falls off rapidly (1/R cubed), but the real casualty effects, over the greatest distances, come from bomb case fragments and secondary missiles created by both bomb blast and fragment strikes on other objects. Effectively, over a considerable diameter cookie cutter, enemy resistance will cease to exist. Any survivors will be greatly degraded in combat effectiveness and, for a time, won't be able to fight at all. A 250-pound bomb shatters defenses and defenders alike in all but the most heavily protected structures. Going back for a moment to the field artillery side of things, one of the great Allied innovations in Western Europe was the invention of TOT (Time On Target) shoots. Where a given weight of HE arrived over an extended period for a standard shoot, the TOT put it down in the snap of a finger. The AARs reported the German survivors were found wandering around in a daze. The 250-pound bomb is, essentially, a miniature TOT, when compared to putting down the same weight of HE via standard artillery fire methods.

Now you know why CAS is done. It delivers a shattering blow in a way field artillery can't hope to match.

Baneman,

I have no idea how BFC handles CAS air-to-ground spotting, but your approach makes eminently good sense, both from a a) I'm the CAS pilot; I'm looking for a target, and you sure look like one and if I'm a friendly on the ground, am prone and something goes Boom, I'm much more likely to survive, especially since Hide means practicing extreme intimacy with the ground. Other things being equal, movement is much easier to see than that which is static, and that which is above the ground is far more readily seen than that which is of pretty much the same elevation as the ground. Therefore, anyone with an inbound CAS strike would do well to imitate your example.

Regards,

John Kettler

[JonS]

The MSD is based on the break point in which a fragment no longer has the ability to pierce the skin, since it's velocity is insufficient to do so.

Unsurprisingly, given the source, this assertion is wrong. That's kind of unfortunate, because it seems to be fundamental to everything else that follows. Bear that in mind when reading the rest of the post from which it came.

Also, Erwin: MSD != 'blast radius'

[John Kettler]

JonS,

I didn't make the statement, the Air Munitions Data (Appendix 2) did.

"The distances listed represent the range at which a fragment from the particular munition will not penetrate the skin of an individual standing in an open field. The figures are based on a probability of kill of zero (Pk=0)."

Additionally, while it's fair to use the term blast radius in the cookie cutter wargaming sense, in reality, blast isn't much of a factor unless quite close to the detonation. Therefore, a more accurate characterization would be Radii of Casualty Effects vs Protected and Unprotected personnel.

Finally, it would be wise not to confuse the properly sourced message with the messenger, toward whom your animus has been heavily publicized.

Regards,

John Kettler