Cepheus SRD Errata

[mike wightman]

Correct. But the volume it occupies depends on the pressure and temperature it is stored at. ;-)

True if it is a pressurised gas forced into the liquid state, but you are storing it as a cryogenic or potentially an artificial gravity field compression to the liquid state liquid... pressure has very little to do with it if you are keeping it liquid cryogenically.

The reason we use cryogenic liquid hydrogen as a rocket fuel rather than pressurised hydrogen gas/liquid is the pressure vessel would be so massive the rocket wouldn't take off in the first place.

This has actually got me thinking - does it actually state anywhere in Traveller that the liquid hydrogen is cryogenic or grav compressed. It can not be a pressure vessel since that would take up considerable space within the hull, and yet fuel tankage in traveller is considered to be just the fuel which has implications to the storage method.

 

[whulorigan]

Correct. But the volume it occupies depends on the pressure and temperature it is stored at. ;-)

I was just trying to point out how silly this discussion is. It's inappropriately Terran-centric to assume Earth pressure and temperature as the norm for determining what volume a certain mass of hydrogen will fill.

(I wanted to say the Imperial Standards office was on Reference, which makes more in-setting sense, but the gravity is too light there to make the hand-wave work.)

I do not really have an iron in the fire in this discussion, but just to be clear:

The definition of a liquid is that is (largely) "non-compressible", meaning that it always fills approximately the same volume for the liquid phase of its temperature/pressure range, unlike a gas which can expand and contract with temperature and pressure. Removal of pressure (or increase in temperature) will cause a liquid to remain at (roughly) the same volume until a critical value is reached, at which point it will boil into its gaseous phase. Sufficiently high pressure (or low temperature) will cause it to transform into a solid phase.

 

[jaymin]

Touche. I guess I'll have to try harder to prove how silly this discussion is.

 

[Timerover51]

The following quote comes from the bottom of page 120 concerning ship construction.

Standard: A standard-hull ship may still enter atmosphere but is very ungainly and ponderous, capable only of making a controlled glide to the surface. Getting it back into space requires an elaborate launch setup and considerable expense.

As near as I can tell, this "elaborate launch setup and considerable expense" is not covered any where in the book. Am I missing something, or it is simply not there? There is no mention of it under Starship Economics, where I would expect it to be.

 

[Timerover51]

But that results in *exactly the same result*. The end result is the same. What you get out at the end is the same. I'm not sure why there is an argument there? Timerover, have you built any vehicles yet, that aren't ships? What did you think of them? Try not to focus on real world designs, no design system so far has achieved creating a perfect 1:1 match for real world designs.

Paul, I basically do exactly what you did in Attack Squadron: Roswell, and that is take Real World vehicles and adapt them to the game. I have a large amount of data, some in hard copy and some in digital format, on a very wide range of vehicles. This covers historical land, sea, and air vehicles. I can choose exactly what I want and then adapt as needed.

The biggest problem is trying to figure out armor equivalents, as those are not clearly defined in the rules either, and the application is more than a bit strange. The following statement appears on page 121 under the Ship Construction Rules.

For example, a heavily armored warship might take Bonded Superdense armor twice. This would take up 10% of the hull’s volume and cost 100% of the base cost of the hull, but give 12 points of armor

Emphasis added.

Basically, that says that if you add Bonded Superdense Armor twice to a 1000 displacement ton hull, the armor takes up 100 tons of the ships volume. How is that possible? It would mean adding, in English units, about 50,000 cubic feet of armor to the ship. Standard steel armor weighs about 480 per cubic foot. I assume that Superdense means an armor twice as dense as steel, so 960 pounds per cubic foot. That amounts to 24,000 short tons (a short ton is equal to 2,000 pounds) of armor to the ship. That is on par with the total armor carried by the Japanese Battleship Yamato. And all that mass of armor only increases the cost of the hull by a 100% and supplies an armor protection of 12. Do your deck plans reflect that loss of all of that internal space to armor? Is there any reflection on the addition of all of that mass in your Maneuver Drive requirements?l All of that mass has to be accelerated in some manner. Then there is all of the framing and supporting structure within the ship to support that massive weight.

Now, if this ship was a nautical vessel, 1000 dTons will equate to about 14,000 displacement tons, based on about 14 cubic meters per dTon. One cubic meter of water is equal to 1 metric ton. The ship now weighs 24,000 short tons or 21,772 metric tons plus whatever the rest of the ship weighs. It promptly sinks, as it weighs far more than the water it displaces. Has anyone bothered to stop and think about what that rule statement implies?

 

[Timerover51]

On page 79, under Common Vehicles, the Tech Level 9 Destroyer carries 6 gunners and no weapons.

The Ground Car has an armor of 6, while the submersible has an armor of 3. The submersible has to deal with a lot of outside pressure that the ground car does not. That should imply a higher level of armor for the submersible. The motor boat has the same level of armor as the sub.

 

[Timerover51]

This question concerns Personal Armor, pages 67 and 68.

The armor Tech Levels given in the table do not match the armor Tech Levels given in the written description for Cloth, Hostile Environment Vacc Suit, Mesh, and Vacc Suit. In the Table, the Hostile Environment Vacc Suit is listed at Tech Level 12 and in the written description at Tech Level 8.

 

[middenface]

This question concerns Personal Armor, pages 67 and 68.

The armor Tech Levels given in the table do not match the armor Tech Levels given in the written description for Cloth, Hostile Environment Vacc Suit, Mesh, and Vacc Suit. In the Table, the Hostile Environment Vacc Suit is listed at Tech Level 12 and in the written description at Tech Level 8.

Written descriptions are correct. The table is not.
The POD version corrected this.
I replied to a post elsewhere and I mentioned this already.

 

[Timerover51]

Written descriptions are correct. The table is not.
The POD version corrected this.
I replied to a post elsewhere and I mentioned this already.

Standard: A standard-hull ship may still enter atmosphere but is very ungainly and ponderous, capable only of making a controlled glide to the surface. Getting it back into space requires an elaborate launch setup and considerable expense.

As you have responded to that issue, how about this one?

Then there is the issue of armor taking up part of a ship's volume. Perhaps you could explain that as well.

 

[Straybow]

I believe that this is how armor was measured going back to High Guard. A ship is defined by volume, and so armor takes up volume. Normally we would put the armor on the outside, but that would make the ship bigger, which changes it's size. So the armor volume is deducted instead of added.

 

[atpollard]

Let me jump into the discussion with a specific proposal.

Page 120 of the SRD currently states:

A metric ton of hydrogen measures approximately 13.5 cubic meters, which is rounded to 14 cubic meters for ease of calculations. When drawing floor plans or maps of ships, each square measuring 1.5 meters by 1.5 meters, to a height of 3m up from the floor, represents half a ton.

I respectfully suggest the following alternative wording:

A metric ton of hydrogen measures approximately 14.1 cubic meters, which is rounded to 14 cubic meters for ease of calculations. When drawing floor plans or maps of ships, each square measuring 1.5 meters by 1.5 meters, to a height of 3m up from the floor, represents half a ton. Two squares measure 13.5 cubic meters or approximately one displacement ton.

This change effects nothing in the actual design sequence, it simply rewords the explanation of a displacement ton to be more factually accurate. This is clearly not an urgently needed change, just a simple suggestion to polish the prose whenever you get around to an update of the SRD to incorporate any significant corrections.

 

[atpollard]

Those readers that live outside the USA and are probably more comfortable with Metric units than Imperial measures, are advised to avert their eyes and read no further. What follows is for my fellow luddites that cling to the foot, the pound and the inch.

TimeRover made a comment on dTons and deckplans that is worth repeating.

1 displacement ton (dTon) is close enough to 500 cubic feet to ignore the small fraction of a percent difference. That means that 1000 cubic feet (a 10'x10'x10' cube) is equal to 2 dTons.

So how big is that Starship you want to build in non-metric units?
Well, let’s say you want a 200 dTon ship (Free Trader size).
200 dT x 500 cu.ft/dT = 100,000 cubic feet.
100,000 cu.ft. / 10’ ceilings = 10,000 square feet.

So a ballpark starting point for the rough size of the ship is ...
Single deck ship = 10,000 sq.ft. per deck = 10’x100’x100’ or 10’x50’x200’
Two deck ship = 5,000 sq.ft. per deck = 20’x50’x100’
Three deck ship = 3,333 sq.ft. per deck = 30’x33’x100’

When it comes to working on deckplans, the 1.5mx1.5m floor grid can be treated as a 5’x5’ floor grid with each square still equal to half a dTon.

So if you find it hard to visualize in metric, 500 cu.ft per dTon and 5’ squares works out the same and may help you get a feel for the sizes.

 

[mike wightman]

5' is 1.524 metres, so a 5' square is pretty close to a 1.5m square...

 

[atpollard]

Basically, that says that if you add Bonded Superdense Armor twice to a 1000 displacement ton hull, the armor takes up 100 tons of the ships volume. How is that possible? It would mean adding, in English units, about 50,000 cubic feet of armor to the ship. Standard steel armor weighs about 480 per cubic foot. I assume that Superdense means an armor twice as dense as steel, so 960 pounds per cubic foot. That amounts to 24,000 short tons (a short ton is equal to 2,000 pounds) of armor to the ship. That is on par with the total armor carried by the Japanese Battleship Yamato. And all that mass of armor only increases the cost of the hull by a 100% and supplies an armor protection of 12.

There is some handwave and some simplification for playability and some apples-to-oranges involved here. How many nuclear missile strikes could the Yamamoto absorb before it was “mission killed”? But mostly, how is any of this errata for the SRD? A topic on the meaning of Armor would be fun, but this is not it.

Do your deck plans reflect that loss of all of that internal space to armor?

Probably not errata, but if the ship was designed correctly, then the dtonnage was allocated and the dTons allocated to armor would not be drawn as living quarters or bridge “squares” since each had its own tonnage allocation that was translated into deck squares (plus or minus 10%).

Is there any reflection on the addition of all of that mass in your Maneuver Drive requirements? All of that mass has to be accelerated in some manner.

Meaningless for NON REACTION drives (grav drives) which operate by volume rather than mass. For REACTION drives, mass calculations are simplified for playability. That is just a fact of the game. This, too, does not seem like an errata in the SRD, but something that should have a topic to discuss the effect of Mass on Reaction Drives.

Then there is all of the framing and supporting structure within the ship to support that massive weight.

Not errata, but you have answered your own question concerning the volume of all that Armor added to the ship. If the volume of the Armor includes internal bracing, then your earlier calculation has overestimated the volume and weight of the armored shell.

Now, if this ship was a nautical vessel, 1000 dTons will equate to about 14,000 displacement tons, based on about 14 cubic meters per dTon. One cubic meter of water is equal to 1 metric ton. The ship now weighs 24,000 short tons or 21,772 metric tons plus whatever the rest of the ship weighs. It promptly sinks, as it weighs far more than the water it displaces. Has anyone bothered to stop and think about what that rule statement implies?

Most tanks don’t float either. You will need to be more specific about what wording in the SRD needs correction and what specifically is wrong with it. If you have a specific real world ship you are attempting to create, post it in a topic and let’s see what can be done with the rules to simulate that design. It may reveal errata, but it is not errata all by itself.

You created this topic to focus on errata for the SRD.

 

[Timerover51]

Most tanks don’t float either. You will need to be more specific about what wording in the SRD needs correction and what specifically is wrong with it. If you have a specific real world ship you are attempting to create, post it in a topic and let’s see what can be done with the rules to simulate that design. It may reveal errata, but it is not errata all by itself.

You created this topic to focus on errata for the SRD.

Although you are not a moderator, I know when I am being told to shut up.

I will keep working on my own version of the rules, and no longer worry about the Cepheus Engine System Reference Document or anything connected to it.

 

[aramis]

Although you are not a moderator, I know when I am being told to shut up.

I will keep working on my own version of the rules, and no longer worry about the Cepheus Engine System Reference Document or anything connected to it.

[m;]He IS a moderator.[/m;]
That is what the

indicates.

You are not being told to, as you inelegantly put it, "shut up." You are being asked by him as a thread participant to stay on topic and focus on actual errata, and justify what is being suggested.

THen again, for actual CE errata, Jason Kemp the only one who actually gets to decide what the official errata is. We can discuss and suggest, but in the end, CE is Jason's.

If you were being asked to "shut up", it would be in moderator text, and/or would be done in a formal warning. Not something that happens much.

 

[Timerover51]

[m;]He IS a moderator.[/m;]
That is what the

indicates.

You are not being told to, as you inelegantly put it, "shut up." You are being asked by him as a thread participant to stay on topic and focus on actual errata, and justify what is being suggested.

THen again, for actual CE errata, Jason Kemp the only one who actually gets to decide what the official errata is. We can discuss and suggest, but in the end, CE is Jason's.

If you were being asked to "shut up", it would be in moderator text, and/or would be done in a formal warning. Not something that happens much.

I will quit asking questions then.

 

[atpollard]

Although you are not a moderator, I know when I am being told to shut up.

I will keep working on my own version of the rules, and no longer worry about the Cepheus Engine System Reference Document or anything connected to it.

Hey TR.
Just for the record, I was just posting as a user and pointing out that a lot of your discussion was not errata (wording in the SRD that needed to be changed or clarified) as much as it was just general questions about using the SRD to design a Water Ship (as distinct from a starship). By placing the questions in a topic on errata, it creates the impression that something is broken when you have not defined exactly what it is that is broken.

That can drive some people crazy. (Fortunately, I have a double dose of mellow about anything not belonging in The Pit ... so I infrequently post in the Pit).

I would just really like (as one gearhead to another) a chance to discuss the details of designing a "Cruiser" or "Battleship" in a topic dedicated to that. Then we can check out the rules and ask questions about the nuts and bolts and get input that will be helpful to lots of people. From there we can see if there really are any "broken" rules or alternative rules that might be worth suggesting to the SRD publisher.

So if you have one specific ship in mind, post some real world stats on a new topic and let's see how close we can get with the rules.

[As an aside, the points that you raised that I didn't mention, I thought were legitimate questions to ask concerning errata. It should describe the additional boost needed for higher Gee takeoffs somewhere in the rules.]

 

[Condottiere]

That's pretty much expected and assigned role(s) and performance.

By default, a battleship is expected to stand in the line of battle and duke it out, while a cruiser is a multirole ship that's cheaper and easier to maintain in service, that can take on everything but a battleship.