AI Values

Sharpe · **Sharpe**

I think that in a given situation, we can posit that the tank will choose one weapon system and maximize its use of that. Dividing their efforts wouldn't result in any greater effect, I believe.

The only wrinkle, as you astutely foresee, is point blank fire, especially versus cover. I prefer KISS, but we could use an idea here.
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Zeus · **Zeus**

In general, high velocity HE shells would be slightly less effective than low velocity HE shells due to the high velocity shells tending to bury themselves in the ground more. On the other hand, the high velocity HE shell would probably be more accurate, so in the end this probably evens out... This would mean that the barrel length doesn't matter that much.

What does matter for HE shells is the amount of explosive filler, which translates directly to power and size of the blast. I don't think we should look to calibre alone!

I also think that the basic dedicated close support vehicle, usually carrying a 75mm low velocity gun with around 0.7 kg of exlosive filler (like the Sherman M4A1, Panzer IV A-F1, T-34 and the 75mm in the B1 bis), should have a reasonable chance of taking out a 4/4 Soldier, even if they didn't have any MG's at all. This would mean 9/8/7 for these guns. If the vehicle does have MG's, this wouldn't add to this attack value - it's like throwing pebbles at something after already throwing a big rock!

You might remember though that I do think the main purpose of a vehicle's MG (other than the early idea of using them to sight the main gun) is close-up AI defense, and thus an MG in the turret or hull should give a vehicle the possibility of def fire against Soldiers. So having the MG still makes a big diff!

It's actually funny how this whole discussion made me somewhat of a proponent for separating a vehicle's HE and MG stats on the card (allowing an effect on cover for HE attacks among other things), and now the trend is to go back to one value Smile

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HHRgamer · **HHRgamer**

Separate MG and HE attack values.

Zeus, I still like the idea of separating the HE and MG attack stats, but I am afraid no one will have the time, inclination, and energy to get them figured out anytime soon. Thus my suggestion to go with a simpler approach first, and let the separate stats be a future FA project. If there are members who want to put in the time to develop the separate stats now, I suppose there could be parallel tracks. Any takers out there?

MG defensive fire
It seems we have general agreement that vehicle machine guns were used for defensive fire against infantry. Sharpe, I would include the AAMG in this category, but if the leaders of the project are of a different opinion then so be it. I would suggest that rather than using SAs, we should make defensive fire for MG-equipped vehicles a basic rule. The fire value may, like armor value, vary depending on where the MGs are located and where the target is located (e.g., a vehicle with only hull MG would only have defensive fire at targets straight ahead; a vehicle with hull MG and turret mounted MGs may have one number for straight ahead and another number for side and rear). SAs could be used for really unusual configurations (perhaps rear turret, rear hull?). This would avoid cluttering the card with too many SAs.

Close and short range AI fire.
There appears to be agreement that for some vehicles there was a meaningful choice in some situations between attacking infantry with MG(s) or HE. Sharpe posits the choice applies to close range (point blank), but I think it also applies to short range, as defined in the post on page 3 of this thread. For whatever range is agreed on, perhaps there is a way, per Sharpe's observation, to bring this choice to life without violating KISS. The gun's HE value would be listed in the attack stats, and an SA would state that the player, for __ range attacks, can choose to use MGs at a value of ____, but in doing so will lose the -2 to cover that HE provides.

HE values.
Zeus, this summer I started trying to look up the amount of explosive filler for the projectiles fired by various vehicles, but the more I read about the question the more important other factors also appeared to be: the thickness of the shell, the material the shell was made of, the design or shape of the shell, whether the shell depended mainly on shrapnel or on the pure explosive effect (concussion?). Even projectile velocity would seem to vary depending not only on the length of the barrel, but on the tightness of the fit (friction), the amount and type of propellant, and other factors.

In theory one could develop a model based not only on explosive charge, but on a plethora of other factors. I question whether anyone at this point has the time or inclination to put the model out there, or to provide the statistical information which will be necessary to apply the model to each gun/projectile combination that occurs in the game.

Absent development of such a model, I think the most straightforward and KISS approach should be to assume that long barrel guns were high velocity and had relatively less effective HE, and short barrel guns were low velocity and had relatively more effective HE, all other factors being equal. The rationale is that if a given gun was expected to be mainly used for AP (armor piercing) rather than HE, design compromises would be made in favor of AP. The converse would also be true. Exceptions, based on specific facts, could be adopted case by case.

Next steps.
Thanks for the feedback. I'll revise my proposed numbers for vehicles with 75mm guns once I get some direction from this discussion as it develops. Once we get some numbers based on the WOTC conventions, it shouldn't be that hard to develop numbers for the FA variable ranges previously proposed. Then maybe we can get some proposed cards!

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HHRgamer

HHRgamer · **HHRgamer**

In light of the comments from Zeus, Sharpe, and Buzzkill, I'd like to clarify the approach I took in the post dealing with vehicles carrying 75mm guns, to re-examine my assumptions about the basis for AAM's AI numbers, and to set out my view of what FA vehicle AI numbers should represent.

Clarification.
First, when I proposed alternative AI values for vehicles equipped with 75mm guns, I was assuming that AAM's AI values were based on a combination of main gun and MG values. By combination, I mean that I thought AAM had used HE as the point of departure for the attack matrix values, and increased those values for vehicles that were also equipped with MGs. I now believe that the AAM vehicle AI numbers are based on the main gun alone. I also believe that, with a slight modification discussed below, this is a workable approach.

What is the basis of AAM vehicle AI values?

Marder v. Pz IVD--F1.

The Marder, with a 75L46 gun (and no MGs), gets a 6/5/4,
whereas the PzIVD--F1, with a 75L24 (& 2 MGs) gets a 7/7/6.

The Marder was a tank destroyer, equipped with the same high-velocity anti-tank gun as used in the PAK 40. (http://www.probertencyclopaedia.com/cgi-bi/res.pl?keyword=Marder&offset=0) The Pz IV, versions D-F1, were originally used as infantry support tanks, and equipped with a low velocity gun. (http://www.battle-fleet.com/pw/hs/panzer4) 430m/s. (http://en.wikipedia.org/wiki/Panzer_IV). This difference in mission would in part explain why the barrel of the Marder's 75mm gun is almost twice as long as that of the Pz IV D. Thus contrary to my first impression, it appears the difference in the AI values here is due, not to the presence of MGs on the Pz IV D, but to the difference between the two guns.

Su-76 M v. Pz IVD

The Su-76 M, with a 76.2L41 gun & no MGs, gets a 7/7/6,
and the PzIVD--F1, with a 75L24 (& 2 MGs) also gets a 7/7/6.

"The SU-76M combines three main battlefield roles: light assault gun, mobile anti-tank weapon and mobile gun for indirect fire." Main gun velocity for HE was 680 m/s (700 m/s with AP). This is higher than that of the Pz IV D (430m/s), but still both guns are in the low velocity category. Thus both guns get the same AI rating, and the presence of two MG's on the IV D makes no difference to that rating.

What should FA vehicle AI values represent?

As suggested above, the AAM model (for vehicles, not AT guns) appears to be to base vehicle AI values on the main gun only. This makes sense for the reasons pointed out by Sharpe and Zeus. The short time alloted to a phase (1 minute) would realistically encompass acquisition of the target, a decision on what weapon and ammunition to use, and firing. Also, in most (but not all) cases, the main gun will have HE available and the value of that HE will be higher than the MG value. The HE value will also provide a cost-free bonus of a -2 to the target's cover. Thus a rough and ready approach would be for FA, like AAM, to ignore the vehicle MG, with the exception that FA would recognize the MG for defensive fire.

by contrast, Sharpe suggests a modification to this approach which would incorporate those situations in which the MG provides a higher attack value than HE. This would be achieved by combining HE and MG values, but in a manner different from what I had proposed. Rather than taking HE as a point of departure and adding points for MGs, Sharpe would evaluate the value of each weapon at each range and then plug into the chart the higher of the two values. Thus, at close and short ranges, the AI value in the attack matrix would in some cases represent vehicle MGs rather than HE, whereas at medium and long ranges the value will always be the HE (because of the limited range of vehicle mounted MGs).

I agree that FA rules should reflect the value of vehicle MG fire as an alternative attack method in the more common or significant situations where it would make sense to fire the MG instead of the main gun when attacking infantry. However, I think the value of the MG in such situations can be reflected without including MG values in the attack matrix. We should stick with the earlier decision that the values in the attack matrix should always represent the vehicle's main weapon, whatever it is.

My alternative proposal is that for those vehicles possessing machine guns that provide a higher attack value at a given range than the corresponding attack value of the main gun, there should be an SA providing as follows: "Vehicle machine gun." "When this vehicle attacks soldiers at _____[close, close or short] range, the player may choose to attack with value X [or values X/Y] rather than the value appearing in the attack matrix above. Attacks using this special ability do not get the -2 to the target's cover roll." The main rules can make clear that this SA simply represents a crew decision to fire at soldiers with the vehicle MG(s) rather than the main gun.

As to vehicle MG defensive fire, I think it is so common that it should not be an SA. Instead, the card for each vehicle capable of defensive MG fire will have, in the upper left hand portion, the defensive fire values (X/Y/--, or X/---) superimposed over the icons for the MGs that are present on that vehicle.

Comments, anyone?

Next step: propose revised 75mm gun stats based on HE value alone.
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HHRgamer

HHRgamer · **HHRgamer**

Proposed Vehicle AI Values, ver. 2.0
(9.07.09)

1. Objective and general approach
The objective of version 2 is to develop a more historical set of vehicle anti-infantry (anti-soldier) values than in AAM, but without introducing the level of complexity that would be necessary to separately represent all of each vehicle's anti-infantry weapons. Thus version 2 generally assumes the vehicle will attack soldiers with either the main gun or a machine gun, whichever is the more effective weapon in a given situation. Exceptions, indicated by an SA, will provide for player choice in those situations in which the MG would give a higher attack number. Such attacks do not get the benefit of the -2 to cover that applies to attacks by the main gun. Vehicle MGs, but not the main gun, may be used for defensive fire against soldiers.

2. Main gun
The AI (Anti-Infantry) values in the attack matrix on each vehicle card will reflect the main gun's values, regardless of whether the vehicle's main gun is a large caliber gun, an autocannon, or a machine gun.

If the main gun is capable of firing high explosive ammunition, an appropriate icon or notation ("HE" or an image of an explosion) will appear next to the infantry icon on the left side of the attack matrix. All vehicles which have a "High Explosive" icon (or notation) next to the infantry icon in the attack matrix will have the "High Explosive" capability, as follows: "When this vehicle attacks enemy soldiers with its main gun, the the target gets -2 to its cover roll." Only the icon or notation will appear on the card, thus avoiding repetitive clutter of what is in effect a standard SA.

Certain large guns with HE ability will also receive the "Blast" SA as follows:

SA: "Blast — When this unit attacks, make a separate attack
roll against each unit in the target hex. (This includes friendly
units.)"

This language will appear on the cards of the affected vehicles.

3. MG attacks--SA.

For those instances in which a vehicle is equipped with machine guns that provide a higher attack value at a given range than the corresponding attack value of the main gun, the vehicle card will carry the following SA:

"Vehicle machine gun." "When this vehicle attacks soldiers at _____[close, close or short] range, the player may choose to attack with value W [or values W/X] rather than the value appearing in the attack matrix above. Attacks using this special ability do not get the -2 to the target's cover roll."

This SA simply represents a crew decision to fire at soldiers with the vehicle MG(s) rather than the main gun.

4. MG defensive fire.
The card for each vehicle capable of defensive MG fire will have, in the upper left hand portion, an appropriate MG icon. Vehicles can only use MG defensive fire against soldiers when the vehicle is in plain terrain. When the vehicle is in terrain that blocks line of sight (L/O/S), it cannot engage in defensive fire against infantry. This is based on the historical vulnerability of armor to close assault in forests and cities.

5. MG Ranges.
Ranges and their corresponding alpha symbols are as follows:

W close (same hex) (100 yds max) all MGs
X short (1-2 hexes) (200 yds max) all MGs
Y medium (3-5 hexes) (500 yds max) all except hull MG
Z long (6-8 hex) (800 yds max) only AAMG, TTMG (turret top, cupola or pintle mounted)

Note: vehicle MG's at medium and long range may be irrelevant if the HE values of the main gun end up being greater. If this turns out to be correct, we will be back to Sharpe's proposed principle #4 above: "MG's don't count over 200m."

6. Values generally.
Vehicle AI values should be calculated in relation to the probability that the weapon used (MG or HE) will destroy or disrupt a standard infantry unit, rated 4/4. The target soldiers are assumed to be using caution and taking advantage of any available cover. Thus the AI values, and corresponding probabilities of inflicting destruction (kill) or disruption, are, with acknowledgments to Sharpe, as follows:

10+ = very probable kill
9 = probable kill
8 = probable kill or disruption
7 = less probable kill, more probable disruption
6 = improbable kill, less probable disruption
5 = very improbable kill, slight disrupt
4 = unlikely disrupt

7. MG Values.
Vehicle MG values will be lower than corresponding infantry MG values because of the gunner's more limited visibility from the vehicle's periscope or firing slit, and because of the vehicle's motion.

Just as armor values vary by location of impact [per Neural Dream's post], vehicle defensive fire values will vary. For the sake of simplicity and playability, each vehicle's total defensive fire capability will be expressed by a line of values (W/X/-- or W/--) for targets directly in front of the vehicle and another line of values value for targets to the side or rear.

Typically the "front" line of values will represent fire by the front hull MG, if any, plus whatever other MGs could historically fire simultaneously to the front (e.g., the CoAx, a cupola mounted MG, a pintle mounted MG, or an AAMG). The "side and rear" line of values will represent fire by whatever MGs could simultaneously fire at targets in other directions. Defensive fire from vehicles with unusual MG or crew configurations (rear turret MG, rear hull MG) can be represented by separate lines for "rear" and or SAs.

Thus the AI defensive fire value of a vehicle with only a hull MG against a target directly in front of the vehicle would be expressed by "front" and a series of numbers, slashes, and blanks superimposed over the MG icon appearing on the upper left of the card, as follows: "Front: 6/4/--/--." The vehicle has a DF value of 6 against soldier targets directly in front of it in the same hex, and a DF value of 4 against soldier targets one or two hexes directly in front. The vehicle has no DF capability against soldier targets to the side or rear, so the next line would be "Side/rear: --."

[Specific proposed values to be posted later]

8. HE Values.
To distinguish the various vehicle main guns, the following factors may be considered: barrel length, velocity, explosive charge.

A prompt and comprehensive examination of all factors with regard to the HE effect of all vehicle main guns is beyond the capacity of the author, and, apparently, the forum. However, it seems likely that the lower velocity and shorter barreled guns will generally have higher HE value for close and short ranges. Higher velocity and longer barreled guns may have higher HE values for medium and long ranges, because of the increased accuracy at these ranges, and no diminution of HE effect upon impact at range (unlike AP which has less penetration at longer ranges).

I plan to post specific proposed HE values for various 75mm vehicle mounted main guns shortly, and would be glad to receive comments and suggestions.
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HHRgamer

Angel of Death · **Angel of Death**

Looking forward to the HE gun values.
Part 7 (MG's) didnt process to well in my mind. But its late and I just drove 500 km today so maybe its just my mind.
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There are no desperate situations, there are only desperate people.
Heinz Guderian

HHRgamer · **HHRgamer**

I admit part 7, MG values, is a bit rough. I didn't drive 600 km before writing it, but I was perhaps suffering from the effects of manual labor from the day before.

The idea is to come up with two sets of values that will appear on the face of the card: One for MG defensive fire against targets in front of the vehicle, and one for MG defensive fire against targets located in any other direction. To the extent that more than one MG could realistically (based on layout, crew assignments) made DF simultaneously, that ability would be figured into the appropriate line of values.

For example, if a vehicle had a front hull MG and a cupola MG (on top of a turret), and different crew members were assigned to operate each, then the values would assume that both MGs could DF simultaneously. The "front" value of such a vehicle might be something like "6/5/---," whereas a vehicle with the same hull MG and no additional MG might be something like "5/4/----." This is not a huge difference, but enough to be significant over time.

Does this make more sense?
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HHRgamer

HHRgamer · **HHRgamer**

This is a bump to refer interested parties to my 8 November 2009 post on the Tiger I and Tiger II thread in the FA vehicles subfolder.

The post discusses possible theoretical underpinnings of a method for deriving vehicle anti infantry values based on the main gun's high explosive, rather than on machine gun fire. The post is there because it is prompted by Neural Dream's query on that thread, "how does one stat HE?"

There seems to be a reasonable way to calculate HE's "blast effect" (concussion, or blowing things up) based on percentage of the HE projectile which consists of explosive charge. There also seems to be a way in which to estimate the "fragmentation effect" (area within which fragments from an exploded projectile are lethal to personnel).

For FA purposes, it appears to me that we should stick to the blast effect to keep things simple. The MG defensive fire option and limited MG direct fire SA (instead of firing HE--discussed above) may make fragmentation redundant, or so marginal as not to be worth the extra complication. Does anyone have any thoughts on this?
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HHRgamer