One Battle, Two Tanks, Three Systems: Design, Complexity and Outcomes

A while back, I wrote a post about Phoenix Command, detailing a squad-level firefight and talking a little bit about how the rules were extremely detailed. A good friend of mine mentioned in a comment that for all its complexity, the system was actually no more realistic than simpler rules systems.

I suspect that's probably right and it got me thinking about writing a blog post that shows the results of three combat systems and looking at how they work across the same battle. Just to make things interesting, I'll be using armoured vehicles and just looking at how things go in a fictional battle between an M1 Abrams and a T-72. Because I want to look a bit at how vehicle movement influences combat, I'll have the tanks start off at 500 meters distance from each other traversing an open field.

My main interest in doing this is to answer a few questions such as: How are these games different or similar in terms of mechanics (meaning what factors influence timing, accuracy of fire, penetration, and damage)? Do the games with added rule complexity "feel" more realistic and does the end result have a more meaningful or interesting impact on the game versus simpler designs? I'm not trying to start a debate about tanks.




1. Fire Team




For a game that is supposed to represent WW3 in Central Europe in the late 80s, it is surprising to find that there are no T-72s here for the Russians in the counter mix. Instead, we have T-80s and T-62s for our MBTs. I'm going to use a T-62 versus an M1A1 Abrams tank in this situation.

Since we're looking at a turn-based combat system here, it's not as easy to represent a situation where the tanks are moving and shooting at each other simultaneously. To make up for this, we'll be playing a bit fast and loose with section 6.6 of the rules for Moving Fire and Opportunity Fire.

The tanks spot each other from 6 hexes distance. The T-62 is moving towards the M-1 tank, which was also moving in the previous impulse. The American player declares Opp Fire and plunks down his command points to activate the M1A1.

The M1A1 will be using its HV of 16 as the type of main gun ammunition. We compare this HV value of 16 to the T-62's front armor value vs. HV, which is 8.

We consult the HV differential table of 8 to see which row of the kill table to use and find that we are using the bottom-most row.  The range is 0-7 hexes so we are using the left-most column of the kill-table, which means we will kill the T-62 on a roll of "9" or less on a d10 roll.

However, to reflect the idea that the American tank is moving, I'll be assessing a 2-column shift penalty to the right for the M1A1 tank (it would be 3 columns but we are using the advanced rule for Superior Fire Control - 18.1).  This means the Abrams kills the T-62 on a "7" or less die roll.

We roll a 6 and the T-62 is destroyed. If we had rolled over a 7, the M1A1 would have missed and there would have been no effect.

Just for fun, we'll see what happens if the T-62 gets off a last split-second round at the M1A1.

The T-62 has an HV value of 14 while the M1A1 has an HV front armor value of 12. The differential is 2 and that means we are rolling on the 4th row of the kill table. At 6-7 hexes of range, we are rolling on the 2nd column from the left on the kill table. This gets shifted over three columns for moving fire. The kill number is 3 or less.  We roll a 9 and the T-62 misses the M1A1.

Result: M1 destroys T-62 tank. T-62 misses M1.
Time taken to determine result: less than 10 minutes
Table lookups: 3 (Column Shift table, Range table, Kill table)
Number of relevant pages of rules: 2 pages


2. Twilight: 2000 (ver 2.2)



Okay, I'm cheating here a bit by using a roleplaying combat system but it fits neatly in the middle of the complexity range between Fire Team and Phoenix Command.

We need to have crew skill ratings. I will make all crew members completely average with attributes of 5 and skill levels of 5 dealing with their respective position in the tank (ie. drivers of both tanks get Ground Vehicle: Tracked at 5 and have an Agility of 5, etc.).

Twilight: 2000 uses combat turns that are five seconds long. Characters have an initiative number that determines the order and number of actions they can take. Characters with high initiative ratings may be able to do more than one action in a turn but generally, most will only be able to perform one action. I am working with averages here so I'll set all character initiatives to 3 in this battle.

Here we go:

The M1 and T-72 are driving towards each other from 500 meters away.  They are both moving on-road at 35 meters per turn, which is their safe combat movement speed.

It is initiative step 3. Both tank gunners spend the turn aiming. Five seconds pass. Initiative step 2 comes up. Both gunners fire at each others' tank.  Since both gunners have the same initiative number, the shots are simultaneous.  The M1 has a weapon stabilization rating of "Good", so it could actually be going up to twice its safe combat movement speed (70 meters per turn) and still conduct aimed fire if the gunner wished. The T-72 has a stabilization rating of "Basic" so it can only conduct aimed fire at the safe combat movement speed (35 meters per turn).

Let's check the M1's shot first. We look up the T-72's size rating, which is 1 (this is because it takes up a single grid-square of 10 meters).  There is no hit modifier due to vehicle size.

Next, we check the Fire Control stat for the M1 and it is rated +2. That means we can ignore 2 non-range difficulty modifiers to this shot. Great, that means we can ignore the usual +1 difficulty increase for the T-72's speed.

Now we roll to hit.  After the first turn, the tanks were 430 meters apart from each other. That puts us at short range, rated an Average skill shot.   For the M1 gunner, we will be rolling for a hit on a 16 or less with a d20. We get a 5 and the APFSDS round slams into the T-72 tank.

Before we do damage, let's do the same for the T-72 tank.  It has only a +1 for fire control but in this situation it doesn't really negatively impact the to-hit rating.  Again, we are rolling for a 5 or less on a d20 to hit.  We get a 4 and the APFSDS round hits the M1.  Both tanks are hit simultaneously. Michael Bay would be proud.

APFSDS vs. T-72:

The penetration (PEN) value of the APFSDS round at 430 meters from a 105mm gun is 100 +2d6, for a final penetration value of 110. We roll for hit location and get a hull front hit on the T-72 and compare the penetration value of the round to the armor rating of the target in the hit location. The T-72 has a hull front rating of 100.

110 > 100 so the round penetrates the T-72 and we get to roll a minor damage result on a table. We roll a 1 on a 1d6 and a random crewmember is wounded. The driver takes 1d6 hits of 1d6 damage each. We get a 5 for our first roll. The five rolls result in 21 points of damage, including two hits to the head for double damage.  The driver is seriously wounded and the T-72 stops in its tracks.

Since the tank armor has been penetrated, we have to roll to check if the crew bails out. We do this by rolling 1d6 and comparing the result to each crewmembers' Initiative rating. If the die result is over the rating, the crewmember bails. We get 3 for the commander, who is okay, and a 5 for the gunner, who decides enough is enough and gets out of the tank.

APFSDS vs. M1 Abrams:

The PEN of a APFSDS round from a 125mm gun is 100 + 2d6 (we get a 10 for a 110 total) at short range. We roll for hit location on a d6 and get a 1. The M1 Abrams is hit in the hull front.  The M1 has a hull front armor value of 160 so the T-72's round does nothing but scratch the paint up.

Result: T-72's round fails to penetrate M1 hull front. T-72 crew injured/abandons tank.
Time taken to determine result: 15 minutes
Table lookups: 5 (vehicle card, firing chart, vehicle hit location, vehicle damage resolution, human hit location)
Number of relevant pages of rules: ~11 pages


3. Phoenix Command - Mechanized Combat System



This is a big step up from well, pretty much anything, in terms of rules detail. For each tank, we have four pages of stats and charts. Compared to Twilight:2000's nice friendly half-page vehicle card, this thing looks like a Russian novel.

In this system, we have 8 second turns broken up into four 2-second phases. Distance and speed are measured in mechanized hexes that are 20 yards each, compared to Twilight:2000's 10 meter square grid.  To be fair to PC, it has a set of basic rules -- but we're going with the full bells and whistles here and using the advanced rules to resolve this battle.  We'll also be using an M1A1 and the T-72M1 in this battle, as these are listed in the vehicle compendium at the back of the book.

As per our Twilight:2000 battle, the vehicles are starting out moving at a distance of 500 meters (547 yards or about 27.5 hexes away from each other).

For movement, we need to first determine the gradient or slope that the tanks are traversing as well as the kind of surface upon which they are traveling. For the sake of ease, we'll say that both tanks are approaching each other at 0 degree slope traveling on hard ground.

The M1A1 moves 6.5 hexes (130 yards) per turn while the T-72M1 travels 8.6 hexes (172 yards). At the end of our 8 second turn, the tanks will be 12.4 hexes (248 yards or 226 meters) away from each other. The M1A1 has a 1 per cent chance each turn of stalling over this kind of ground.  We roll a 23 and it does not stall. The T-72 tank has no chance of stalling so we don't need to roll for it.

The gunners in each tank will spend 4 phases (the entire turn) aiming. We look up the aim time modifiers for each tank on their status sheet. The M1A1 gunner gets a +14 to his ALM while the T-72M1 gunner gets a +8 modifier.

To find out our hit chances,we start off by determining the total of all modifiers that result from time spent aiming, environmental conditions, range, and crew skill.  This is called the ALM Sum.

M1A1
Range 12: ALM -1
Crew Skill - Line: ALM +10
Aim Time 4: ALM +14
ALM Sum: 23

T-72M1
Range 12: ALM-1
Crew Skill - Line: ALM +10
Aim Time 4: +8
ALM Sum: 17

The movement of each tank will affect the chances to hit. We need to determine the modifiers here by doing a few quick calculations.

To determine the effect on the accuracy of firing at the moving T-72M1, we consult table 5C and cross reference the type of ammunition being used (APFSDS) with the speed of the target in mph or hexes. We get a modifier of 0. This is added to the M1A1's Moving Target Accuracy Modifier (back to the status sheet) and we get a +12.  This final number is called the Moving Target Stability Index.

To determine the effect on accuracy of firing from a moving M1A1, we consult Table 6 and cross-reference the terrain type, velocity of the shooter, and the range to target. The result is -19 and we add this to the Moving Shooter Accuracy Modifier, which is +20. The total Moving Shooter Stability Index is +1.

Next, we find the Ballistic Accuracy of the gun and round. The M1A1 gets a BA of 16 at this range with the APFSDS.

Now the smallest of the four values (ALM Sum, Moving Target Modifier Stability Index, Moving Shooter Modifier Stability Index, and Ballistic Accuracy) is added to the target size modifier and the total is used to determine the final Effective Accuracy Level (EAL), which determines the to-hit chance. So the smallest value is +1 (Moving Shooter Modifier Stability Index), which we add to the T-72's target size modifier (it is 0 degrees facing turret and hull), which is +18. The EAL is 19 and so the to-hit chance is 60%.  We roll a 37 on a percentile and the round hits.

Before we calculate the damage (if any) to the T-72, let's see what happens with the T-72's simultaneous shot.  It's already apparent from our previous tallies for the M1 that the biggest factor for hitting will be the Moving Shooter Modifier Stability Index so we'll only calculate it. This time we get -21 on Table 5C and add this to the T-72's modifier, which is +12, for a total of -9.

The M1A1 is a bigger target with a size of 19 so the total EAL is 10 and the chance to hit is 12%. We get a 52 and the T-72M1 misses its target.

Now to calculate the effects of the M1A1's shot:

First, we find out where the round hit. We get a 92 on the basic hit location table and the result reads Hull Face. We roll again on the advanced hit location table and find that the round strikes the Lower Glacis. The round has hit dead on, so there is no Glance Modifier to calculate. Effective penetration at this range with the APFSDS is 31H and the lower glacis has an Armor PF of 17H. The round penetrates the hull front armor and goes through to the fuel compartment.

We roll for explosion and fire chance and nothing happens. The round continues to penetrate into the ammunition compartment and again we roll on the explosion and fire table with no result. Finally, the round goes through into the engine/fuel compartment. There is no explosion but a roll of 03 on the fire table means that a fire has broken out in the T-72M1 and the crew has 4 phases (8 seconds) to abandon the vehicle. The round passes out the rear of the T-72M1, still with penetrative power left.


Result: T-72 shot misses M1A1. T-72 crew abandons tank.
Time taken to determine result: 1 hour
Table lookups: ~18 (too numerous to relate)
Number of relevant pages of rules: ~31 pages



Conclusion:

Okay, we've looked at three different systems simulating pretty similar battles. It's fairly clear to see that all three systems favored the American MBT quite heavily. All three systems produced startlingly similar results. All of them took in pretty much the same factors (movement, firepower, weapon stabilization) to arrive at these conclusions. Although Fire Team didn't explicitly take crew quality into account, it is heavily implied in the designer's notes that this was "hard-factored" into unit abilities instead of put into a table or chart.

The main advantage of having a very complex rules system like Phoenix Command is that it is actually kind of interesting to see exactly what the M1's round is doing as it enters the tank and penetrates each system. Was it a realistic outcome? I have no idea. I thought it strange that the APFSDS went through the fuel and ammunition compartment without any result before starting a fire in the engine. But hey, I'm not a professional tanker so I dunno if that is likely or not. In any case, the payoff in detail for all that work didn't really seem worth it in the end as I crunched numbers and flipped back and forth through tables and rules.

Of course, the rules systems are all meant to work for different games and different gamers. Fire Team represents squad and platoon-level combat so it would be impossible to go into great depth or detail to represent combat on a detailed level like Phoenix Command. On the other hand, Twilight: 2000 is a roleplaying game that centers around characters and the players need to know what is happening to their guys on an individual level in combat. This level of detail is still pretty good for a roleplaying game although the system can get unwieldy if there is a large battle with tanks and infantry (which is why the Last Battle system was created).  On the other hand, I think I would get much more quickly overwhelmed with anything more than just two tanks moving and shooting at each other using the Phoenix Command system. That being said, I at least admire it for what it is trying to do and there are actually times when I crave that level of detail.

In the end, I suppose it comes down less to realism than to how you get your gaming fix. If you are a sucker for detail and challenging rules systems that try to account for everything, there is simply no better system than Phoenix Command. On the other hand, if you like your combat quick and greasy and with just enough bells and whistles, Fire Team lets you keep moving and focused on the overall tactical battle on the board rather than mired in the minutiae. For something in between, Twilight: 2000 managed to capture vehicle combat on an individual level that was tense and meaningful for the players and kept your game group entertained.  Take your pick but be careful about confusing added levels of detail with more realism.

Comments

  1. Interesting post, Brad. Rules I play (Modern Spearhead) would bring tank on tank action (scale is nominally three tanks per base though, not 1) down to four main things: spotting & shooting range (higher ground has better range / units in cover are often not spotted until they themselves shoot / smoke may have an effect), who gets first shot (ambush fire goes before stationary fire which goes before moving fire), terrain (target hull down / in cover is harder to hit) and finally gun vs armour match ups. In a straight fight, a T-72 has an armour rating of 9/3 (frontal/side) and an M1 a rating of 10/4. T-72 shoots 18" with a strength of 10; M1 21" at 11. T-72's gun vs armour of 11 will suppress on a 5 or 6. The M1 at strength 11 vs 9 will suppress on a 2 or 3 and kill on a 4-6. Sucks to be the T-72 unless you get to fire first and have some buddies around to help out!

    Cheers,
    Aaron

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    1. (Incidentally, this is why we mostly play late '70s - M60A1s vs T72s makes for a much more interesting fight!)

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    2. Good to hear from you, Aaron! I really dig those late 70s WW3 AARs of yours. The M60 was no slouch either but it makes for a bit more interesting fight, I would definitely agree!

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  2. The problem with all these games is that they are products of the writer's environments. The older the game, the more we see of the "Soviet superman" and less of the "Soviet dunce". In the post-Gulf War period we see the reverse. In neither do we actually see an understanding of the rationale behind the Soviet tank design. Nor do we see appreciation that the Soviets built different tanks for different allies. The T72s encountered in the Gulf War were specifically manufactured for the Iraqis. Their armour was weaker than the T72s manufactured by the Warsaw Pact allies. Their guns fired plain steel penetrators, rather than Tungsten cored ones. After the end of the Cold War, the Germans tested East German T72s and declared that they were invulnerable to all (including US Army) NATO anti-tank weapons. Yet, only a few months later the Iraqi Army had T72s blowing up, left, right and centre. Now, either the Germans got their testing wrong or the vehicles were very different between what the NVA used and what the Iraqi Army used. The US Army actually confirmed what the Germans had discovered. The T72 that the NVA used was very different to the Iraqi Army version. It had ceramic armour inserts, the Iraqi ones didn't.

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    Replies
    1. I don't usually reply to anonymous comments but I'll bite in this case. It wasn't my intention to compare tanks and I knew going in to this blog post that I'd spark an old debate anyways. I got the impression from reading the design notes in all of these games that the authors were all trying their very best to go on the information they had at the time of publication. As you state, the consensus at that time is reflected in the results but what's interesting to me is that the designs are capable of producing these same results no matter the complexity level of the rules.

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