Hulls - Take 2 - Mass Effect?

Well, the first try at hulls wasn't too bad overall but wouldn't it be nice if the design of a reaction drive spacecraft could be entirely mass based?   Of course the automatic answer to that it yes, but what about hull plating/armor and surface area considerations?

After much searching and way too much reading, I may have come up with a... not solution but perhaps a workaround.  It seems that quite a few people who evidently are nearly as insane as myself, have calculated out the densities of various ships in Traveller.  The figures seem to mainly fall between 4 metric tons per displacement ton and 7 metric tons per displacement ton.  A value of 4 metric tons per displacement ton seems to be in the ballpark of the mass/volume budget I consider  right for the Dark Stars setting.

This figure might seem high at first, given that 50% of your average deep space craft's mass is in fuel with a density of  less than 0.1 but engine shielding and storm shelter shielding should go a long way to help make up for it.

So, if an average density around 0.29 metric tons per cubic meter is assumed, an enclosing hull can be designed for a given mass - which gives the surface area and hull plating/armor figures.  Seeing as how they are guesstimates anyhow, I think it might be worth a try.  While I'm at it, 1 m/s^2 seems a better fit to Dark Star as a drive rating than 2.5 m/s^2 so we'll refactor that in too.

Now the fun part is refactoring yesterday's hull design formulas into today's new and improved variant.

First we need a modified configuration table:

Code	Atmospheric rating	Hull cost modifier	Material structure modifier (Sm)
0	Non-atmospheric	1.0	1.0
1	Partial streamlining	1.2	1.2
2	Streamlined	1.5	1.5
3	Lifting body	2.5	2.5

Our structural factor formula becomes:
Sf = (Mt/4000)^(3/2); where Mt is the total wet mass of the spacecraft in metric tons.

And our structural rating formula becomes:
Sr = Sf * Sm * Gt * Ga * 0.1; where Gt is thrust in m/s^2 and Ga is agility in m/s^2 (Gt >= Ga >= 1).

Our minimum Sr remains 1.

Now are armor multiplier formula becomes:
AMV = 10/(0.25*Mt)^(1/3)

And our armor factor is now:
Af = Ar * AMV * Sm; where Ar is the armor rating.

Note that for now I'm going to punt on the exact definition of Ar.

Our minimum Af remains 1.

And our material rating (Mr) is still:
Mr = Sr + Af

The craft percentage by tech level now changes to include a base price per metric ton.

TL	Percent of craft	MCr per ton
8-9	2.0%	0.10
10-11	1.5%	0.15
12-13	1.0%	0.20
14-15	0.5%	0.25

Now the hull mass is given:
Mh = Mt * Pc * Mr; where Pc is the percentage of craft from the table above.

And the hull cost is:
Ch = Mh * Ct * Hcm; where Ct is the MCr per ton from the table and Hcm is the hull cost modifier.

Finally, because what I was formerly calling hardpoints may also be used for non weapon mounts, I decided to change the name to mount points.  The formula for determining the maximum number of mount points also changes:

Mp(max) = 0.75 * (0.25*Mt)^(1/2); where Mp is the number of mount points.
Turns out I need a new mount point formula, the correct one follows:
Mp(max) =  0.75 * (Mt)^(2/3); where Mp is the number of mount points

So the entire Mp(max) column in the following table is kaput.

Mass of craft	Sf	AMV	Mp(max)
50	0.01	4.31	2
100	0.01	3.42	3
150	0.01	2.99	4
200	0.02	2.72	5
250	0.02	2.52	5
300	0.03	2.38	6
350	0.03	2.26	7
400	0.04	2.16	7
450	0.04	2.08	7
500	0.05	2	8
600	0.06	1.89	9
700	0.08	1.79	9
800	0.09	1.71	10
900	0.11	1.65	11
1000	0.13	1.59	11
1100	0.15	1.54	12
1200	0.17	1.5	12
1300	0.19	1.46	13
1400	0.21	1.42	14
1500	0.23	1.39	14
1600	0.26	1.36	15
1700	0.28	1.34	15
1800	0.31	1.31	15
1900	0.33	1.29	16
2000	0.36	1.26	16
2500	0.5	1.17	18
3000	0.65	1.11	20
3500	0.82	1.05	22
4000	1	1	23
4500	1.2	0.97	25
5000	1.4	0.93	26
6000	1.84	0.88	29
7000	2.32	0.83	31
8000	2.83	0.8	33
9000	3.38	0.77	35
10000	3.96	0.74	37
12500	5.53	0.69	41
15000	7.27	0.65	45
17500	9.16	0.62	49
20000	11.19	0.59	53
22500	13.35	0.57	56
25000	15.63	0.55	59
30000	20.54	0.52	64
35000	25.89	0.49	70
40000	31.63	0.47	75
45000	37.74	0.45	79
50000	44.2	0.44	83
60000	58.1	0.41	91
70000	73.21	0.39	99
80000	89.45	0.37	106
90000	106.73	0.36	112
100000	125	0.35	118
150000	229.64	0.3	145
200000	353.56	0.28	167
250000	494.11	0.26	187
300000	649.52	0.24	205
350000	818.49	0.23	221
400000	1000	0.22	237
450000	1193.25	0.21	251
500000	1397.55	0.2	265

And... there we are folks, hull stats in mass based form.  Assuming, of course, that 4 metric tons per Traveller displacement ton isn't too far out of line as a guesstimate of the total wet mass of a ship.

For the remainder of the design, volume is pretty much irrelevant. *happy dance*

Errata: I've discovered that I underestimated the number of mount points required once I started including radiators, engine thrust nozzles, etc along with weapons.  I believe the above numbers should at least be doubled, perhaps more.  Err make that x10, seems I forgot a few things!

Addition: It seems I do need a 'length' factor for a few things, most realistic combat hull configurations will fall within the figure given by the following formula within 25% or so, for others it doesn't really matter.  Lf = 1.25*(7*Mt)^(1/3).  It's a little more funky even than the other formulas but it should serve the purpose.