Carrying capacity by tech level
- Thread starter parmasson
- Start date
by Jeff M. Hopper
Food Flavored Nutrient Product ™ available in
Spicy, Vilani, Neo-Chutney, Salty, Mild, Newberry
-and Introducing
Extra Firm Coffee Juice Flavor!
If you want the ™ open MS Word and type(tm)and word will automatically create it. Then just cut and paste into the message box. COTI seems to know the symbol and posts it. Same thing for the © symbol, (c).
Food Flavored Nutrient Product ™ available in
Spicy, Vilani, Neo-Chutney, Salty, Mild, Newberry
-and Introducing
Extra Firm Coffee Juice Flavor!
rhoneycutt
SOC-11
thrash...
I already use those ideas in my ship design spreadsheet. Those equations apply to monocoque construction which can be augmented by load bearing framework ala FFS1. Granted, you won't get 'supertakers' that can pull 6 G's, but bulk freighters don't have to. Small, or even fractional, G's are quite good enough to get a ship from the jump limit to orbit. All this means is that extreme care must be taken in regards to mass, and not just volume.
You seem to assume that all trav ships can pull 6 G's in your paper which in this case is like assuming a 747 or c-130 can perform like a f-15. Try increasing the structure volume, or using a material that has a better toughness to mass ratio than BSD. Allow large ships to use small accelerations and all is fine.
but this is getting away from the topic.
if we can allow for multi-square-mile lighted warehouses, then why not supertanker spaceships?
I already use those ideas in my ship design spreadsheet. Those equations apply to monocoque construction which can be augmented by load bearing framework ala FFS1. Granted, you won't get 'supertakers' that can pull 6 G's, but bulk freighters don't have to. Small, or even fractional, G's are quite good enough to get a ship from the jump limit to orbit. All this means is that extreme care must be taken in regards to mass, and not just volume.
You seem to assume that all trav ships can pull 6 G's in your paper which in this case is like assuming a 747 or c-130 can perform like a f-15. Try increasing the structure volume, or using a material that has a better toughness to mass ratio than BSD. Allow large ships to use small accelerations and all is fine.
but this is getting away from the topic.
if we can allow for multi-square-mile lighted warehouses, then why not supertanker spaceships?
rhoneycutt
SOC-11
High Guard's assumption is a bad one.
There is no way of knowing if FFS's structure is 'inadequate' without knowing its design. Space frames are very strong which is why skyscrapers use them. At least it does attempt to portray real physical limitations.
Why must they be proof against 'substantial' collisions? Impacts would be rare and involve huge energies anyways...enough to penetrate armor easily for any object of substantial mass. Why must any non-combat ship be rated to withstand weapon fire?
A large freighter that uses a percentage on its volume for internal structure still has more cargo volume than many small ships that give away internal volume to drives and accomodations and fuel and stuff, all of which requires more maintainence.
BSD does not have the best toughness to mass ratio. I use the list prepared by Edward Fok. There are a few composites and synthetics with much better ratios although they do take up more volume, and possibly cost more. The cost is eased as some of them appear at tech 9 and not tech 14. So at tech 14, the costs would perhaps be comparable ( also they allow hulls to be built on lower tech worlds )
There are no physical upper limits to ships in space...only economical limits.
This is my position and how I work things in MTU. If we are going to continue this, perhaps we should move to a different topic heading.
There is no way of knowing if FFS's structure is 'inadequate' without knowing its design. Space frames are very strong which is why skyscrapers use them. At least it does attempt to portray real physical limitations.
Why must they be proof against 'substantial' collisions? Impacts would be rare and involve huge energies anyways...enough to penetrate armor easily for any object of substantial mass. Why must any non-combat ship be rated to withstand weapon fire?
A large freighter that uses a percentage on its volume for internal structure still has more cargo volume than many small ships that give away internal volume to drives and accomodations and fuel and stuff, all of which requires more maintainence.
BSD does not have the best toughness to mass ratio. I use the list prepared by Edward Fok. There are a few composites and synthetics with much better ratios although they do take up more volume, and possibly cost more. The cost is eased as some of them appear at tech 9 and not tech 14. So at tech 14, the costs would perhaps be comparable ( also they allow hulls to be built on lower tech worlds )
There are no physical upper limits to ships in space...only economical limits.
This is my position and how I work things in MTU. If we are going to continue this, perhaps we should move to a different topic heading.
High Guard's assumptions? High Guard is so abstract that you can as well assume that structural reinforcement is part of the percentage alloted to the maneuver drive, or indeed other components, as well. What is definitely assumed, btw, is that spaceships have inertial compensators.
Furthermore, this source, with whose author you apparently have some contact, gives the same formula for structural volume, but with one caveat:
What, now? Is the equation Vsb = (V1.15 * (Apg0 * D)0.453) / 300 to be disregarded for very large vessels or not? If it is, as the quote certainly implies, most of your point for small ships flies out of the window, doesn't it?
Regards,
Tobias
P.S.: I was gonna do some calculations, but recent experience tells me it's unwise to tangle with such things at 4 AM.
My guess is that regardless of the maximum freighter size some food stuffs will be produced locally if the local economy is sufficiently advanced. Political will would probably have some part to play as well. The U.S. might be able to meet its own energy needs but it would requite a SUPER BIG MAJOR restructuring of the urban fabric to make it happen. In our case the funds are available and the technology exists but the political will does not. Probably the same thing would happen with with food. A vacuum world with a high enough tech level dedicated to food independence could make it happen. A world that didn’t have the will or see a need would let the freighters haul it in. The reality would most likely be somewhere in between. Higher value food products (fruit, wine, cheese, dairy, non vat meat) would most likely be shipped in from off world. Day to day soy products, F.F.N.P.s and other greens might be cheaper to produce locally in tapped out mine galleries that are already wired up for power and have freight moving equipment in place.
What I have gleaned from this discussion is that in the OTU large freighters must exist say at least 500kt+. MegaTraveller BI-15 battleships were 750kt IIRC. Shipping in those vessels will not come cheap so the non Ag world in question must have certain level of affluence just to afford the cost of the products. A well organized and stable TL-12 vacuum world could support billions with a combination of imported and domestically produced foods. Worlds with breathable atmospheres but huge populations and heavy pollution may find it cheaper (economically and politically) to import rather than detoxify the soil.
What I have gleaned from this discussion is that in the OTU large freighters must exist say at least 500kt+. MegaTraveller BI-15 battleships were 750kt IIRC. Shipping in those vessels will not come cheap so the non Ag world in question must have certain level of affluence just to afford the cost of the products. A well organized and stable TL-12 vacuum world could support billions with a combination of imported and domestically produced foods. Worlds with breathable atmospheres but huge populations and heavy pollution may find it cheaper (economically and politically) to import rather than detoxify the soil.
The note on the website sounds pretty much as if he was sure of it.
I am skeptical of that equation. I mean, it does not take into account the material used at all. It doesn't matter for stability whether I use steel, titanium, BSD or balsa wood? That seems improbable.
Regards,
Tobias
Mr Thrash;
Two questions, if I may:
Why haven't you taken inertial compensators into account?
Why are you assuming monocoque construction?
High Guard implies a certain amount of "free" structure in that there are no volume or cost requirements for fuel tankage beyond that of the fuel itself. Also, virtually all published deckplans show extensive compartmentalization as well as fore-and-aft decking (often multiple decks). All of this is again "free" in that there are no rules governing the cost/volume of internal bulkheads or decks.
Two questions, if I may:
Why haven't you taken inertial compensators into account?
Why are you assuming monocoque construction?
High Guard implies a certain amount of "free" structure in that there are no volume or cost requirements for fuel tankage beyond that of the fuel itself. Also, virtually all published deckplans show extensive compartmentalization as well as fore-and-aft decking (often multiple decks). All of this is again "free" in that there are no rules governing the cost/volume of internal bulkheads or decks.
Yes, I noticed that. There, you said he was sure, here you say he wasn't. So, was he sure or not?
That's as good an opinion as any other, but irrelevant to the questions at hand. You can make the same argument for anti-grav and meson guns, but it doesn't make sense to discount them altogether if you're talking about Traveller.
This is simply a rephrasing of "V(sb) can usually be disregarded and V(sr) can be assumed as sufficient". Now, is that the case or not? You write "Strength requirements dominate for low-tech materials and very large or heavy vessels. Stability comes into play for small and light vessels using high-tech materials, which otherwise would have very thin (but strong) structural members."
But the application of the equations actually yields the exact opposite. For example, a TL 14 200kton ship with an assumed density of 2tons/m³ rated at 6 Gs needs ~8500 dtons V(sr) but 22000 dtons V(sb).
Yes, you did. At which point I have to ask: How did you arrive at the (k^0.368) and how could you assume that advanced materials would have the same E as steel, seeing as some materials existing now have considerably greater E?
But the "contents" of the vessel play quite a role here. If all the interior components are affected by the inertial compensators, their mass should be disregarded from the density of the vessel as far as structural requirements are concerned. (Not because their mass is nullified, which it is not, but because they do not exert stress on the ship's structure.)
Actually, as far as I know, there are shapes which resist buckling considerably better than cylinders do, anyway.
Regards,
Tobias
I'm sorry, but if there are contradictions, I usually like some clearing up.
Canon, CT canon especially, is only concerned how materials perform as armor (and thus only lists toughness). How did you arrive at your conclusions about them being equivalent to steel as far as other characteristics are concerned? "Based on this, I have based the assumed structural properties of the ultratech materials on hard steel; this seemed to be the most reasonable approach" doesn't seem to follow from anything else in the article.
You said, in your article, that stability requirements were primarily important for small and light vessels using high-tech components. This is simply not the case using the equations, hence confusion.
Again: Where does this follow from?
Yep, and you treat them as steel, not any stronger, and I was wondering: Why?.
How? If you turn of the Grav Plates, but leave the compensators alone, you have things floating insided the ship, without physical contact with the ship itself. The only way I can think of in which they can transmit stress to the hull is if the inertial compensators themselves "transfer" it to the vessel.
Or you could simply not follow the idea that for structural reinforcement, no materials better than steel will be employed.
Ahem. "Do it better!" is not usually a good response to criticism or questions. When a paper of mine (entirely different field) gets criticized or questioned I can't very well shut up people with this argument, now can I?
Unfortunately, our University library does not have a copy of SMAD III, but a friend of mine who works at the Center of Aerospace Technology can get me access to one. However, you can maybe answer this question in advance: Does the book assume the specific shape you used or is there any provision for different shapes?
Regards,
Tobias
I would also like to go back to topic to state that for the original point of transport capabilities, the question is moot, at least when using CT. A 500kton Bulk Freighter can transport ~100 times the cargo of a 5kton Ship and costs ~100 times more. The only area where the larger ship is noticeably - but not radically - more efficient is the number of crewmembers. In short words, 100 small freighters can do the work of one giant freighter, at the same cost efficiency, and with much more flexibility.
Large ships (above a certain limit) really make sense only for military vessels, including military transports (if only because large ships are more resiliant to damage.)
Regards,
Tobias
Large ships (above a certain limit) really make sense only for military vessels, including military transports (if only because large ships are more resiliant to damage.)
Regards,
Tobias
mike wightman
SOC-14 10K
Emm, there are references to grav plates and acceleration compensators being different things.
Traders and Gunboats page 7:
Then there is this from the Kinunir, page 17:
Safari Ship says this on page 22:
And finally Signal GK says on page 26:
In CT (and MT) canon there is no consideration given to structural materials period. But it would be somewhat bold to assume that we have supereffective armor materials and null-effective structure materials or that starship designers intentionally use materials which are unsuited for the purpose they aim.
I still do not see how you can assume from this that BSD, for example, is not "stiffer" than steel and that the superadvanced construction techniques that make BSD possible do not result in better structural materials.
Yes there is. See Traders&Gunboats for reference. Of course, in CT, all such stuff is simply lumped into the assumed design basics. In MT, where those devices are directly addressed for the first time, they are separately considered.
You should actually rather prove that you're right. In my view, the assertion "Structural materials can be assumed to have the same E as modern steel" is not conclusively proven, even hinted at, by any of the facts you quote. And though you continue to reply: "Tougness =/= E", this is not a satisfactory answer. Moogles are literate. A Toogle is not a Moogle, but this doesn't mean Toogles are illiterate. If Toogles go to the same schools as Moogles, it would actually be reasonable to assume they are literate as well.
You didn't get the gist of the question. Let me rephrase it then: Are, in SMAD III, other shapes than the "cylinder" considered and/or are mathmatical models for those present? (...to bugger my engineering buddies with, or do I need to look for another book for a discussion of other basic shapes?)
Regards,
Tobias
When arguing canon about ships, note that half million dton warships capable of 6G acceleration are canon. Given that they exist, there's no point to arguing whether they're possible -- they clearly are possible. Instead, the goal should be to make sense of possibly conflicting canon.
Our only canon on structural strengths is FF&S and FF&S2, since they are the only design sequences that care about structure. In both cases, it is clear that structural strength does increase at the same ratio as toughness, and therefore Chris' assertion that they can be treated as steel is wrong. Given that superdense and bonded superdense are basically aphysical materials, there's no particular reason they should not get stronger as they get tougher.
The other alternative is to take High Guard literally (which I will note that MT, FF&S, and FF&S2 do not) and assume that manuever drives are a volume effect, which probably means they create a drive field around the ship -- probably it creates an artificial gravity field about the ship, and the ship just falls in whatever direction is convenient. This would mean the drive places zero stress upon the hull, making the entire argument moot.
Our only canon on structural strengths is FF&S and FF&S2, since they are the only design sequences that care about structure. In both cases, it is clear that structural strength does increase at the same ratio as toughness, and therefore Chris' assertion that they can be treated as steel is wrong. Given that superdense and bonded superdense are basically aphysical materials, there's no particular reason they should not get stronger as they get tougher.
The other alternative is to take High Guard literally (which I will note that MT, FF&S, and FF&S2 do not) and assume that manuever drives are a volume effect, which probably means they create a drive field around the ship -- probably it creates an artificial gravity field about the ship, and the ship just falls in whatever direction is convenient. This would mean the drive places zero stress upon the hull, making the entire argument moot.
This is not the point. You can repeat "Strenght =/= E" again and again. I know that. I do know as well, however, that E has widely different values for different materials, that differences are ergo reasonable. You assume that all materials used for Traveller's superscience starships have the same E as steel. This still doesn't follow from anything.
Regards,
Tobias
Strength is not a precise technical term. The canon we have tells us that you need 1/14 as much bonded superdense as steel for the same structural requirements.
Given the information we have, bonded superdense apparently has roughly 200x (14^2) the tensile strength, compressive strength, sheer strength, deformation, heat of vaporization, etc, of steel, while retaining about the same deformation limits as steel. Yes, no real-world material is going to have these properties. BSD is, however, a Superscience material.
As Striker described CG systems, not M-drives, this particular point is irrelevant, though I'll agree that there's significant canon which points to M-drives actually producing force. I'm a proponent of the drive field primarily because it can be twisted into a solution for the near-C rock problem.
Given that the hull of a ship is built around a substantial frame and also given that (at least) this frame is isolated from acceleration effects by the inertial damper system; what effect does this have on your model?
Also, this statement, quoted from your essay, seems incorrect:
"Note also that armor factor 0 still requires a fraction of the hull: 1-4%,
depending on TL. This residual hull "armor" represents the minimal structure
of the ship itself in High Guard."
The design example for the Kinunir (armor factor-0) on pp51-52 of High Guard, makes no allowance for hull structure. Each ship component is listed, and the total listed components come to 1248.8 tons.
Unarmored designs from Traders and Gunboats exhibit the same characteristic.
Also, this statement, quoted from your essay, seems incorrect:
"Note also that armor factor 0 still requires a fraction of the hull: 1-4%,
depending on TL. This residual hull "armor" represents the minimal structure
of the ship itself in High Guard."
The design example for the Kinunir (armor factor-0) on pp51-52 of High Guard, makes no allowance for hull structure. Each ship component is listed, and the total listed components come to 1248.8 tons.
Unarmored designs from Traders and Gunboats exhibit the same characteristic.
mike wightman
SOC-14 10K
The hull armour table in High Guard second edition clearly states that a ship requires either 4+4a, 3+3a, etc.
This means that a ship with an armour factor of zero should use between 4 and 1 percent of its volume for an armour value of zero.
Ship designers appear to have ignored this since day one, but thrash is correct, it is in the rules.
This means that a ship with an armour factor of zero should use between 4 and 1 percent of its volume for an armour value of zero.
Ship designers appear to have ignored this since day one, but thrash is correct, it is in the rules.
mike wightman
SOC-14 10K
Which means virtually every ship ever designed with HG2 is broken
... or alternatively HG2 needs more errata
... or alternatively HG2 needs more errata
Yes, but the text reads pretty much as: "You can select armor. If you do, use the following procedure..."
Armor selection is not an integral part of hull design. Granted, if you had only the letter of the rules, it could be read either way. But the example clears it up. No armor = Disregard step 8 entirely.
It's an non-important point, and I didn't mention it, because a certain amount of default structural tonnage can be assumed anyway (for example, as part of the maneuver drive tonnage.)
Regards,
Tobias
Similar threads
