TNE FF&S Mass Driver Design: Damage and Penetration

[snrdg082102]

Does a mass driver have a Damage Value and Penetration parameters?

If, yes where do I find the formulas?

 

[whartung]

Damage and penetration is calculated under the "Munitions" section, as I recall. But it's pretty basic.

I just went through this a little while ago. I was doing one for a 2cm auto-cannon. The numbers at TL-12 were pretty crazy. But I compared FFS 1 and 2, and they pretty much use the same numbers. There's definitely an errata of some kind involved there, I forget the details.

 

[snrdg082102]

Damage and penetration is calculated under the "Munitions" section, as I recall. But it's pretty basic.

I just went through this a little while ago. I was doing one for a 2cm auto-cannon. The numbers at TL-12 were pretty crazy. But I compared FFS 1 and 2, and they pretty much use the same numbers. There's definitely an errata of some kind involved there, I forget the details.

Evening (PDT) whartung,

Thanks for the reply. I did take a look at the Munitions section but wasn't sure. The best errata I have is the CONSOLIDATED TNE ERRATA, v0.02 (09/19/09) by Don McKinney which came with a TNE bundle purchased from DriveThruRPG.com. There wasn't, at least that I could see, any mention of correction to munitions for FF&S Mk 1 Mod 0.

Do you think T4 FF&S might help?

 

[whartung]

Evening (PDT) whartung,

Thanks for the reply. I did take a look at the Munitions section but wasn't sure. The best errata I have is the CONSOLIDATED TNE ERRATA, v0.02 (09/19/09) by Don McKinney which came with a TNE bundle purchased from DriveThruRPG.com. There wasn't, at least that I could see, any mention of correction to munitions for FF&S Mk 1 Mod 0.

The errata is for the Mass Driver itself, and how it calculate range (page 110). I found an errata on the web, but the Consolidated document matched what I found.

Do you think T4 FF&S might help?

FFS2 is fundamentally the same as FFS1. And I used it to offer a different view of the same topic. Basically after another set of eyes has looked at it.

One thing to note as far as I can tell is that on page 110, the calculation for the mass of the projectile is just wrong. But it's not corrected in FFS1 errata at all.

Basically, the math for the projectile they represent there, (pi*r^3)/10, gives far, far different numbers than the projectile mass table does in the Munitions sections.

T4 doesn't have the formula, just the table.

Consider a 2cm (20mm) round, the math gives us .31416 for mass. In the munitions table, it's 0.2. But this isn't the real issue. The real issue is as you get bigger.

The math for a 4cm (40mm) round is 2.5, while the table is .8.

I was playing with a TL-12 mass driver, as I said. Doesn't really matter, they're much the same after 11, since the velocity peaks at 6000 m/s though the projectiles change for KEAP.

But still the numbers are a bit wacky.

For the 2cm, if you use the mass formula, you get pen values of:
287 - 277 - 267 - 247

Using the table you get:
212 - 202 - 192 - 172

But for the 4cm gun, using the formula...
1277 - 1267 - 1257 - 1237

and the table:
413 - 403 - 393 - 373

Now, frankly, I file these under "WTFOMG" and "Why again do I need fusion guns on my tanks??" With these numbers, a 20mm gauss auto cannon will turn the TL 13 grav tank (max armor of 60) in to swiss cheese. Pretty much one shot, one kill here...

Using the table, a 6cm gun is in the 1500 range (this lets you punch through several tank at once... ).

FFS2 isn't much better, a 6cm gun has a pen of ~690. I assume then pens are basically interchangeable from TNE combat and T4 combat, but I don't know. It's still a big number.

In neither system did I find anything talking about a maximum pen rating for a KEAP round. So, in both systems, they go rather high.

I think I must be missing something somewhere, but I can't find it.

 

[snrdg082102]

Morning whartung,

Much to ponder on this one.

TNE FF&S Mk. 1 Mod 0 p. 139:

2. KEAP: Kinetic energy warheads have a damage value equal to their diameter in centimeters multiplied by 2.2. This is a constant value for use only for direct hits on personnel. It is never used vs. vehicle targets.

I'm not sure but a KEAP munition appears to mean Anti-Personnel not Armor-Piercing.

Blast still need to type more, but I'm running late to hit the gym. (I'd rather skip the gym, unfortunately I all ready skipped once this week.)

To continued

 

[whartung]

I'm not sure but a KEAP munition appears to mean Anti-Personnel not Armor-Piercing.

Oh, no, hardly.

I think the premise there is since KEAP basically just "punches holes", against personnel, they simply over-penetrate and doing damage solely based on their size. For example, it doesn't matter how long a lance is once it sticks all the way through.

Whereas with vehicles, over-penetration is converted directly in to damage. (10 pts per major hit).

So, I read some more and found something more interesting.

If I use the weight formula given on page 102 for "Gauss Weapons", then the numbers seem much, much better.

Consider, respectively, a TL-12 20, 40, and 60mm gun:

20mm: 40 - 35 - 29 - 19

40mm: 80 - 70 - 60 - 40

60mm: 124 - 114 - 104 - 84

These numbers are MUCH better.

It's confusing here. Because on pg 101 is says:

Small arms gauss weapons may be made in any caliber up to 20mm. (Weapons of 20mm and above are usuablly considered to be cannons and are covered under Mass Drivers.) All gauss bullets have a length equal to their diameter multiplied by 5.

So. Now, clearly a difference between a cannon and a small arms rifle, but if you use the small arms calculation, for a 20mm round you get a weight of:

.04 * pi * (10 ^2) [r in mm^2] = 12.56 grams, or .013 kg.

Using the Mass Driver math, we get:

pi * (1 ^ 3) / 10 [r in cm^3] = 314g, or .31416 kg

And finally, if you use the Munitions table, it's simple 200g or .2 kg.

Here, a 20mm round weight 117g.

Perhaps a mass driver is more efficient and can better translate its power in to velocity than a small arm, thus the small arms require lighter rounds.

I dunno.

I'll have to look at T4 in more detail tonight to see if they make the same distinctions.

In any case, the penetration calculation is the same, and it's all based on muzzle energy.

 

[snrdg082102]

Late afternoon (PDT) whartung,

Wow, my head is spinning with the math. I'm also very rusty on how damage is resolved. The Mass Driver, in TNE FF&S Mk. 1 Mod 0 appears to be the only weapon without a reference to Damage Value and/or Penetration.

My translation of KEAP munition Damage Value rule on TNE FF&S Mk. 1 Mod 0 p. 139 means that the calculation is for direct hits on personnel and is not used against hard targets like a vehicle.

The Gauss weapon weight formula in TNE FF&S Mk. 1 Mod 0 on p. 102 is

Wa = .02 x pi x r ^3

Apparently, I'm doing something wrong since I'm not coming up with the same numbers as the examples listed in the quote using the formulas in either the 1st or 2nd editions of TNE FF&S. I mentioned being rusty, I've just revised to I don't have a clue on where the numbers listed in the example came from.

If I use the weight formula given on page 102 for "Gauss Weapons", then the numbers seem much, much better.

Consider, respectively, a TL-12 20, 40, and 60mm gun:

20mm: 40 - 35 - 29 - 19

40mm: 80 - 70 - 60 - 40

60mm: 124 - 114 - 104 - 84

Could you please show me the process for one of the examples? If the process is to long please send me an email.

Yippee , I came up with the same answer for

pi * (1 ^ 3) / 10 [r in cm^3] = 314g, or .31416 kg

I'm not even close to being a ballistics expert, heck I won't even say I'm a novice, so I can't say why there is a difference in the calculations.

Thanks for the help, even the stuff I'm still trying to figure out.

 

[whartung]

Late afternoon (PDT) whartung,

Wow, my head is spinning with the math. I'm also very rusty on how damage is resolved. The Mass Driver, in TNE FF&S Mk. 1 Mod 0 appears to be the only weapon without a reference to Damage Value and/or Penetration.

My translation of KEAP munition Damage Value rule on TNE FF&S Mk. 1 Mod 0 p. 139 means that the calculation is for direct hits on personnel and is not used against hard targets like a vehicle.

Yea, you have to look at the actual combat rules to see how it all works.

Simply put, fundamentally, Penetration == Damage.

Penetration Value is the absolute value of penetration of a weapon, at a specific range.

Penetration Rating is how much energy a weapon loses per armor value.

Damage Value is relevant only to people and animals.

PV literally represents the energy of the weapon. If I take a bullet and shoot it in to a piece of wood, that wood is going to take away some of the energy of that bullet. If you shoot a bullet in to a bunch of boards, eventually it will lose enough energy to either bounce off, or simply stick in to the final board.

How much energy the bullet loses can be considered the PR of the weapon. PV and PR are basically interchangeable.

For a contrived example, let's say you have a bullet with a PV of 100 and it can go through 10 boards before being stopped.

If each board is considered as an Armor Value of 1, then the PR of that bullet is "10". You can see that if there are 3 boards, the bullet would still have 70 PV left after it passed through them.

So, that the basics of how it all works, and KEAP stands out because that's all it does. The round doesn't explode, or turn to gas, or burn holes in things, or spew out grenades and fortune cookies. It goes through the hard parts until it gets to the soft parts and perhaps starts bouncing around.

The Damage Value for KEAP is 2.2 * the diameter in cm (I think). So, for a 20mm round, that 2.2 * 2 = 4.4, which I guess rounds down to 4. The Damage Value is applied as number of Dice against soft targets.

So a 20mm KEAP does 4 dice damage to a person, regardless of its penetration (assuming it penetrates at all). I think that's simply a concession that at this level, a large cannon round is penetrating anything. As a target you're simply not going to slow it down...in contrast to small arms which personal armor can work with. This round is literally going through you, and whatever wound channel it creates is dependent solely on diameter. It doesn't explode when it hits of anything.

So the note about damage to personnel is that the rules about the damage only apply to personnel, not to vehicles. There are different rules for vehicles.

I will be back later tonight and work through the math that I used.

 

[snrdg082102]

Thanks whartung for explaining Penetration and Damage in a way that an old retired submarine sailor understands. I'll be waiting for the math tutorial.

KEAP DV = 2.2 x Bore diameter in cm is correct.

Now the whole thing makes sense a big solid artillery warhead hitting my poor little body isn't even slowed, but I'm jam spread all over the area. The same round hitting a concrete and steel bunker has a lot more resistance and may or may not punch a hole into the interior.

Silly question: Why doesn't a mass driver have Damage and Penetration calculated?

 

[whartung]

Silly question: Why doesn't a mass driver have Damage and Penetration calculated?

Because it's basically designed for vehicles, not people. Only people really need to worry about damage.

So, let's do the math.

Page 110

Section A
1. Tech Level = 12
2. Muzzle Velocity = 6000 m/s since it maxes out at TL 11
3. Projectile = 2cm diameter
   Mass = (pi * r ^ 3) / 10
        = (3.1416 * 1 ^ 3) / 10 
        = 3.1416 / 10 
        = .31 kg

Skip to...
7. Muzzle Energy = 0.0000005 * M * V^2
                 = 0.0000005 * .31 * 6000 ^ 2
                 = 0.0000005 * .31 * 36000000
                 = 5.58 Mj

This is all we need for damage.

We now move down to Munitions.

Page 140, Section F.2 KEAP

First we calculate the base penetration for Medium Range. There's that long list of rules there. These are brackets of Mj ranges. Since our Mj rating is 5.58, it falls between 5 and 7.

The one that affects us is:

if Mj < 7, PV = 7 * Mj, but no higher than 43

So:

BPV = 7 * 5.58
    = 39

This is less than 43, so it stays at 39.

Next, we modify the PV based on the TL of the round. Using that chart, we find for TL-12, our round is APFSDSSD with a modifier of 5. APFSDSSD stands for "Armor Piercing, Discarding Sabot, Fin Stabilized, Superdense".

So, with the new modifier, our final Medium Range PV is:

PV = BPV * TLmod
   = 39 * 5
   = 195

Our final penetration numbers are derived as follows:

Short   Range = PV + minimum(PV * 15%, 10)
Medium  Range = PV
Long    Range = PV - minimum(PV * 15%, 10)
Extreme Range = PV - minimum(PV * 45%, 30)

195 * 0.15 = 29.25, which is greater than 10, so we'll be using the flat 
values of 10 and 30

Short   Range = PV + 10
              = 195 + 10
              = 205
Medium  Range = 195
Long    Range = PV - 10
              = 195 - 10
              = 185
Extreme Range = PV - 30
              = 195 - 30
              = 165

Finally, we'll calculate the range bands. The range band calc in the book, on page 110 is completely wrong. The correct formula is:

Short Range = 5 * (Bore in cm + Muzzle Velocity / 20 + 20)
            = 5 * (2 + 6000 / 20 + 20)
            = 5 * (2 + 300 + 20)
            = 5 * 322
            = 1610 meters

Short   Range =  1610 m
Medium  Range =  3220 m
Long    Range =  6440 m
Extreme Range = 12880 m

So, the final numbers:

Pen Values: 205 - 195 - 185 - 165, Short Range 1610

 

[snrdg082102]

My second attempt at making a reply to you whartung. I was typing, apparently, too fast and somehow sent the signal to go back a web page.

whartung the explanation for determining penetration is awesome, not to mention showing me how to use the code feature. A whole bushel of thanks.

I really hate when what I thought I typed and what actually shows are different. In my silly question the "and" should have been "and/or."

Personally, real world and in the TU, I like the illusion of knowing that the material my character is hiding behind has a really good chance of stopping or minimizing penetration and damage. Stopping both is the top one on the list.

Again, thanks for the help.