Effective armor for small craft, non-cap & capital ships

[DFW]

I've been mulling the armors rules. As everyone knows, all else being equal, the larger the object the larger the ratio between volume to surface area.

Hence, armor factor x that takes "n" % of volume on a 50 ton ship will result in a thinner armor than for 100t ship, which will be thinner than for a 3000 ton ship.

I decided to use the base rule for 100-2000t ships. 10-90t ships will be 75% armor factor and >2000t ships 133% (rounded).

 

[phavoc]

I've been mulling the armors rules. As everyone knows, all else being equal, the larger the object the larger the ratio between volume to surface area.

Hence, armor factor x that takes "n" % of volume on a 50 ton ship will result in a thinner armor than for 100t ship, which will be thinner than for a 3000 ton ship.

I decided to use the base rule for 100-2000t ships. 10-90t ships will be 75% armor factor and >2000t ships 133% (rounded).

True, but a larger ship whould compensate for that. What I find odd is you can get a 100ton ship with the same armor factor as a battleship.

 

[DFW]

What I find odd is you can get a 100ton ship with the same armor factor as a battleship.

That's why I created the rule. It deals with that oddity.

 

[phavoc]

What I find odd is you can get a 100ton ship with the same armor factor as a battleship.

That's why I created the rule. It deals with that oddity.

Oh. I read that in reverse. Your rule makes sense that way.

 

[DFW]

What I find odd is you can get a 100ton ship with the same armor factor as a battleship.

That's why I created the rule. It deals with that oddity.

Oh. I read that in reverse. Your rule makes sense that way.

Not surprised, my writing was sloppy. I forgot the rounding too. Small craft round down, Capital ships round up:

50 ton small craft: 5% bonded = 2.5 tons = 6 x .75 = 4 armor points
3000 ton ship: 5% bonded = 15 tons = 6 x 1.33 = 8 armor points

 

[asciitraveller]

Hi,
i'm a first time poster but long time lurker on this Board. As a physicist, i encountered and approached the same problem in a more mathematical way:

To calculate the armor point cost in dtons for any ships volume, i use:
Cost[dtons]=Volume[dtons] * ShapeConstant * VolumeFactor * TechFactor,

where the ShapeConstant times the VolumeFactor is the ratio of the surface to the volume of the ship. The Volume Factor is always Volume^(-1/3), and the ShapeConstant depends on the - you guessed it - shape ( 3 for a sphere, 6 for a cube, 9 for a cigar etc ... ).
I've chosen the TechFactor to be (1/TL), to represent the different types of armor. Perhaps (0.5/TL) would be better.

Lets Look at some examples:

Volume    ShapeCons  VolFactor  TechFact   Cost        Example
 [dtons]                                   [dtons]      Armor
      10       3       0.464        0.1        1.4        3.6
     100       3       0.215        0.1        6.5        7.7
    1000       3       0.100        0.1       30.0       16.7
   10000       3       0.046        0.1      139.2       35.9
  100000       3       0.022        0.1      646.3       77.4
 1000000       3       0.010        0.1     3000.0      166.7
10000000       3       0.005        0.1    13924.8      359.1

The last column shows the final armor of a ship which uses 50% of the volume for armor.

Also, we get a strong dependence of shape, which excludes distributed or streamlined hulls from beeing well armored. Sadly, nobody would want use small fighters in this scenario. The advantage of larger ships is obvious.
It is a little more complicated to calculate, but as everyone uses spreadsheets, thats a mood point. Also, it would need much bigger damage values for nukes and big guns to penetrate armor of larger ships - which would be more realistic anyways.
Opinions?


P.S: I'm no native speaker, please excuse the errors in spelling. I'm doing my best.

 

[rust]

Looks very good, thank you for the idea.

 

[Ishmael]

it seems to me that , for a given thickness/rating of armor, the percentage it'd take up is proportional to surface_area/volume, aka the square-cube law, all other things being equal.

 

[asciitraveller]

it seems to me that , for a given thickness/rating of armor, the percentage it'd take up is proportional to surface_area/volume, aka the square-cube law, all other things being equal.

In principle you are right, but lets consider a sphere:
Because the surface is proportional to radius squared (r^2) and the volume V proportional to r^3, the ratio between the two is proportional to 1/r. But as we use the volume as we build starships, we have to express the one over r in terms of V. The Radius r is proportional to the cubic root of the volume [V^(1/3)], which yields the factor i used in my formula:

 1        1
--- ~ ---------  = V^(-1/3)
 r     V^(1/3)

Of course the i dropped the fours, threes an pis in the prefactor, but one can easily pull them together into the shape factor.

 

[Ishmael]

In principle you are right, but lets consider a sphere:

that all looks good to me.
Here is pretty much how I've done things.
http://www.mongoosepublishing.com/phpBB2/viewtopic.php?t=47569&postdays=0&postorder=asc&start=28

I don't consider only a sphere, but an ellipsoid, of which a sphere is a subset.
In such a system, the x-sectional area can be width*height * .7854 or some other number ranging from 1 to .5 to account for a shape ranging from a rectangular 'box' to a 'diamond' x-section like a Type 'S'.

 

[asciitraveller]

Here is pretty much how I've done things.

Nice.
One side effect of proper surface calculation is the need for spherical shapes for military craft, while traders would prefer box like configurations for easier docking and loading. The insane amount of armor on bigger ships calls for bigger capital ship weaponry, which in turn could become slow enough to miss small fighters (everyone likes fighters).

 

[locarno24]

which in turn could become slow enough to miss small fighters (everyone likes fighters).

That's one other flaw in the ship combat system - a static fighter is no harder to hit (which is not the end of the world when considering the ridiculous powers of ten involved) but it also is no harder to hit even when it is evading at >8g; it can still only dodge a few shots at DM-2 each.

It apparently doesn't matter that I have a spare pool of thrust twice that of any normal warship, nor that I only have to shift myself a fraction of the distance in the same time to evade a shot (since my cross-section is so much lower). Personally I'd allow a fighter to throw multiple dodges (hence requiring multiple points of thrust) at the same attack.

Equally, as it stands there are no weapons which struggle to hit fighters. Bays, large bays, even spinal mounts can apparently sight up with no problem.