Proposed Alternate Universe Project

[Border Reiver]

The freight ton is the one used in MT rules, 1.35 cubic metres or 13.5kl. Use whatever excuse you want as an accident for it being adopted as the shipping standard and carry on from there.

The liquid hydrogen volume is not a standard anyway as it will vary with temperature and pressure.

 

[Laryssa]

I think we should keep the 1 dton standard, if only so as not to force us to throw out the T20 Handbook. The assumptions I use for my table above is that 1 dton of starship (and whatever is inside) weights 1.35 metric tons as stated in the T20 Book. Since their are 2 drive units for a 100 dton starship that means each drive unit must produce 67.5 tons of force for each 1-G of acceleration it produces. the reactionless drives produce Gs of acceleration, but passengers don't feel those Gs as the reactionless maneuver drive drags a frame of reference that includes the starship. The Grav Plate system is attached to the maneuver drive and that produced 1-G of internal gravity inside the ship no matter how fast and in which direction the ship is actually accelerating it. A reaction drive can be used in conjunction with a reactionless maneuver drive, and you can add the two accelerations together, the passengers only feel the acceleration produced by the reaction drive though.

A solid rocket motor and reaction mass + a 6-G reactionless drive can together produce a combined acceleration of 12-Gs for a limited duration while the reaction mass holds out.

 

[JAFARR]

Well I downloaded the Office 2007 beta. I hope this works like office 97 did.

Proposed hull & armor changes Note: LBB 2 hulls 800+ tons & all custom hulls = cost of HG hulls.
Minimum Tech Level
UPC code Material type Armor Value Cost / dton MCr /200 tn LBB2 200tn HG cost Comments
A 5 Soft steel 0 0.075 15.00 8 20.0 Cannot be armored
B 6 Hard Steel 0 0.080 16.00 8 20.0 Cannot be armored
C 7 Composite Laminate 0 0.100 20.00 8 20.0 Additional armor per chart below
C 8 Composite Laminate 1 0.150 30.00 8 20.4
C 9 Composite Laminate 2 0.225 45.00 8 20.5
D 9 Lt. Wt. Comp. Lam. 0 0.080 16.00 8 20.0
D 10 Lt. Wt. Comp. Lam. 1 0.110 22.00 8 20.4
E 10 Crystaliron 0 0.100 20.00 8 20.0
E 11 Crystaliron 1 0.110 22.00 8 20.4
E 12 Crystaliron 2 0.121 24.20 8 20.5
F 12 Superdense 0 0.100 20.00 8 20.0
F 13 Superdense 1 0.115 23.00 8 20.4
F 14 Superdense 2 0.132 26.45 8 20.5
G 14 Bonded Superdense 0 0.100 20.00 8 20.0
G 15 Bonded Superdense 1 0.110 22.00 8 20.4
G 16 Bonded Superdense 2 0.121 24.20 8 20.5
G 17 Bonded Superdense 3 0.133 26.62 8 20.6
H 17 Coherent Superdense 0 0.125 25.00 8 20.0
H 18 Coherent Superdense 1 0.144 28.75 8 20.4
H 19 Coherent Superdense 2 0.165 33.06 8 20.5
H 20 Coherent Superdense 3 0.190 38.02 8 20.6
H 21 Coherent Superdense 4 0.219 43.73 8 20.7
At these costs, armor value is included in the hull without using any additional hull volume. Additional armor requires hull volume per chart below.


Tech Level Cost for added armor
Start End Hull volume used
7 9 4 + 4(a-b) .3 + .1(a - b)
10 11 3 + 3(a-b)
12 13 2 + 2(a-b)
14 15 1 + (a-b)
16 18 1 + .75(a-b)
19 21 1 +.5(a-b)
These formula give the percentage of hull volume used for armor, where a = armor factor and b = base factor from chart.

EDIT: This was supposed to be in chart form. It looked nice as a spreadsheet and as a word document. Let me try something else.

 

[JAFARR]

Here are my proposed hull and armor changes. As in HG, added armor is max of base TL of ship. Keep planetoid & buffered planetoid hulls as per HG.

</font><blockquote>code:</font><hr /><pre style="font-size:x-small; font-family: monospace;"> Proposed hull & armor changes Note: LBB 2 hulls 800+ tons & all custom hulls = cost of HG hulls.
Minimum Tech Level
UPC code Material type Armor Value Cost / dton MCr /200 tn LBB2 200tn HG 200tn cost Comments
A 5 Soft steel 0 0.075 15.00 8 20.0 Cannot be armored
B 6 Hard Steel 0 0.080 16.00 8 20.0 Cannot be armored
C 7 Composite Laminate 0 0.100 20.00 8 20.0 Additional armor per chart below
C 8 Composite Laminate 1 0.150 30.00 8 20.4
C 9 Composite Laminate 2 0.225 45.00 8 20.5
D 9 Lt. Wt. Comp. Lam. 0 0.080 16.00 8 20.0
D 10 Lt. Wt. Comp. Lam. 1 0.110 22.00 8 20.4
E 10 Crystaliron 0 0.100 20.00 8 20.0
E 11 Crystaliron 1 0.110 22.00 8 20.4
E 12 Crystaliron 2 0.121 24.20 8 20.5
F 12 Superdense 0 0.100 20.00 8 20.0
F 13 Superdense 1 0.115 23.00 8 20.4
F 14 Superdense 2 0.132 26.45 8 20.5
G 14 Bonded Superdense 0 0.100 20.00 8 20.0
G 15 Bonded Superdense 1 0.110 22.00 8 20.4
G 16 Bonded Superdense 2 0.121 24.20 8 20.5
G 17 Bonded Superdense 3 0.133 26.62 8 20.6
H 17 Coherent Superdense 0 0.125 25.00 8 20.0
H 18 Coherent Superdense 1 0.144 28.75 8 20.4
H 19 Coherent Superdense 2 0.165 33.06 8 20.5
H 20 Coherent Superdense 3 0.190 38.02 8 20.6
H 21 Coherent Superdense 4 0.219 43.73 8 20.7
At these costs, armor value is included in the hull without using any additional hull volume.

Additional armor requires hull volume per chart below.











Tech Level Cost for added armor
Start End Hull volume used
7 9 4 + 4(a-b) .3 + .1(a - b)
10 11 3 + 3(a-b)
12 13 2 + 2(a-b)
14 15 1 + (a-b)
16 18 1 + .75(a-b)
19 21 1 +.5(a-b)
These formula give the percentage of hull volume used for armor, where a = armor factor and b = base factor from chart.


</pre>[/QUOTE]Hopefully this is clear enough to make it out. The comment about additional armor applies to rest of the chart below that entry.

 

[JAFARR]

Some explainations may be in order.
I took the structural materials chart from MT and assumed that as a material became avaliable at a given TL with which to build hulls was 0 armor factor for that material. Armor factor 1 plus will take away from the usable hull volume. Note that soft and hard steel hulls cannot be armored. All other materials can be armored above the base armor factor shown in the chart. If there is a TL gap between material types, I proposed that each TL step allowed an additional armor factor be added to the base WITHOUT using hull volume. I.E. to a given point, hull thichness increases will result in additional armor factor increases, but WITHOUT reducing hull volume. When computing the cost of of added armor, remember to subtract any armor value included in the base cost before macking your computations.

For comparison purposes, the chart give the cost of 200 ton hulls from this method, LBB2, and armored HG hulls. I also priced the base "0 armor factor" hulls at the same price as HG Hulls. The 2nd chart is right out of HG with 2 levels added.

Now if the chart looks looks to be good in structure, are the prices in line or do they need to be tweeked?

Those who want to deal with mass, feel free to add that component also.

 

[Straybow]

Originally posted by BillDowns:
Register ton is defined as 100 cubic feet of cargo because that's how the Panama Canal charged; used in US and some European ship cargo measurements.

The register ton was a 19th century British standard. It was used because it worked as an approximation of a proper seaworthy load. It is also an approximation for many dry goods and is used to rate truck bed sizes (pickups, "deuce and a half," etc).

Displacement tonnes which is defined as 35 cubic feet; the weight of "standard" sea water; used for all military ships and actually most ships around the world as a definition of "size".

When you say ship tonnages are defined using the 35 ft³ seawater displacement standard, is that tonnage empty, tonnage fully fueled, or tonnage fueled and loaded? Tons short, tons long, or tons metric?

Furthermore, that only makes sense because the ship is floating in water. When we describe the size of the space shuttle do we use saltwater displacement? No, we use mass.

Lastly, that seawater displacement tonnage only measures the volume below the waterline, not the entire volume of the ship. When you compare overall dimensions the 100 ft³ approximation works well for unarmored surface vessels.

All of these, except the displacement tonnes, are quite arbitrary. Since the largest volume on a Traveller spaceship is the liquid hydrogen fuel, it seems quite reasonable to me to use that as the standard, especially since everything else in Traveller already uses that figure.

Why change from one arbitrary measurement of volume to another?

Fuel is the single largest volume on every conventionally fueled ship, but we don't define ship tonnages by the density of fuel. When you say "everything else in Traveller uses it," that is incorrect. They either make no mention of the volume of a ton or use m³ or kvl volume and then divide by 13.5 or 14 to fit the arbitrary dT.

The reason to change: because the standard is ridiculous, leads to confusion, and doesn't work for cargos.

 

[Straybow]

I think we should keep the 1 dton standard, if only so as not to force us to throw out the T20 Handbook. The assumptions I use for my table above is that 1 dton of starship (and whatever is inside) weights 1.35 metric tons as stated in the T20 Book.

Hmmm, sounds like a good reason to use the T20 Handbook only as the roughest guideline. The real overall mass to volume ratio should be ~5 tons per dT. I suppose the empty weight of a large, low powered, unarmored cargo vessel could be as low as 1.35 tons per dT.

(From Andy's extended HG chart)
4 + 4(a-b)
3 + 3(a-b)
2 + 2(a-b)
1 + (a-b)
1 + .75(a-b)
1 +.5(a-b)
These formula give the percentage of hull volume used for armor, where a = armor factor and b = base factor from chart.

Armor mass should be far higher. On Earth battleships only have heavy armor on the main turrets and a narrow band under the waterline, with less armor is on the bomb decks and minor turrets and little to no armor elsewhere. On such ships armor comprises about a third of the total mass.

To completely encompass a hull with enough armor to make a difference would up the ship's density to the vicinity of a main battle tank. Do a real mass calculation based on thickness and density of materials. The percent increase in overall mass (or the reduction in available volume) to account for the mass of armor will look more like this:

08-09 = 10a
10-11 = 9a
12-13 = 8a
14-15 = 7a
16-17 = 6a
18+ = 5a

[Edit: quote source added to lessen confusion]

 

[Laryssa]

One can always assume the reaction drives are slightly more efficient to compensate, they are still within that order of magnitude.

 

[JAFARR]

Straybow,

Do those numbers look at all familiar? For the most part, they are right out of HG except for the "(a-b)" part which compensates for the basic armor factor in the hull itself and the last 2 rows which are my extension of the TL chart. As to your battleship (BB) analogy, I contend that a ship in water is less vulnerable to gun damage below the waterline while a ship in space is more like an airplane in that it has equal likelyhood of being attacked from any point on it's surface. (Personally, I served on aircraft carriers which had a armored deck for the flight deck and another armored deck above the engineering spaces. Don't know how much armor was in the rest of the ship.)

As to the amount of armor required, where on the TL chart would you place those BBs? My guess is just about TL 6 or 7. What you must consider is the reasoning behind the placement of the armor. Will it be the same for a wet navy ship as for a plane or as for a spaceship? Personally I don't think it will.

I am willing to be persuaded to change my viewpoint if you can prove the logic of point of view.

 

[Laryssa]

So which type of FTL drives do you prefer, we don't have to go with Jump Drives you know.

What do you think about Hyperdrives instead? With the hyperdrive having all properties of the jump drive except the length of time spent is hyperspace is proportional to the distance traveled with the hyperdrive numbers indicating the number of hexes traveled in 1 week's time.

 

[JAFARR]

I have no problem with jump drives. After all, some of the most fun times I have had playing Traveller have been during jump.

Do I understand you to say the equalivant of a jump 2 with hyper drives taked 2 weeks?

 

[Straybow]

Originally posted by Andy Fralix
Do those numbers look at all familiar? For the most part, they are right out of HG except for the "(a-b)" part which compensates for the basic armor factor in the hull itself and the last 2 rows which are my extension of the TL chart. As to your battleship (BB) analogy, I contend that a ship in water is less vulnerable to gun damage below the waterline while a ship in space is more like an airplane in that it has equal likelyhood of being attacked from any point on it's surface.

... What you must consider is the reasoning behind the placement of the armor. Will it be the same for a wet navy ship as for a plane or as for a spaceship? Personally I don't think it will.

Sorry, I'll edit it to lessen confusion. For a design system where mass isn't directly computed you wind up "sacrificing" space to account for the mass. Or it can just be mass added directly to the total. (Another reason why mass and volume need to be accounted for in ship design.)

My point was that a BB only has full armor on the most critical and exposed parts: the main turrets and the torpedo belt. Still, that armor would account for a third of the mass. Therefore, to cover an entire hull in a thickness of armor sufficient to defeat main armaments should take far more material.

At any tech level basic structural integrity will require a certain thickness of material. Against small arms it would be considered "armor" but against main armaments it is insignificant. So the additional percentage of mass dedicated to armor will be a large percentage of the unarmored mass, for each point or level of protection. Covering the whole hull with the best armor should add more than 100% to the initial mass of the entire ship (not just the empty hull). Perhaps far more than the unarmored ship mass.

So, I suggest starting lower techs with a very high mass "cost" of 10% per point, dropping incrementally. Furthermore, armor is not merely going to be more of the hull material. Armor may be in the same class as hull material but somehow treated differently to provide protection from energy weapons and the like, or it may be an entirely different material.

Naturally, the sheer quantity of high-tech materials required for armor makes it prohibitively expensive. Then ship designers would be forced to make decisions about how much they are willing to spend on armor. Covering mission-critical parts will again be the priority and other parts will be covered as mass and money allow.

If the design/maneuver/jump system is the volume only type then mass calcs are mainly there to derive the cost of the materials and assembly charges. Until somebody wants to land away from a spaceport...