Starship Volumetrics (Update)

[B.J.]

Honestly, I was thinking a 50,000 to 75,000 ton NCC-1701 would probably work out.

Sounds ridiculous but it has twice the volume of a modern aircraft carrier...

What is the volume of a modern aircraft carrier?

Related question, why use a carrier? I would think that a destroyer or cruiser would be a better choice for comparison due to a carrier having all those specialized structures/etc. to support aircraft & flight operations.

And no, I don't think a submarine would be a better choice over a destroyer.

 

[CuttingEdge100]

Newtype Alpha,

I don't know actually, but I do remember in one of the Enterprise Blueprint Threads which were done by Shaw and Cary L. Brown said something to the effect that the Enterprise had about twice the volume of an aircraft-carrier.


B.J.

I selected a carrier because it was the closest in size and volume.

 

[Crazy Eddie]

In short, at no point do we see thrust anywhere near what would have to be assumed for an antigrav-free take-off as you are suggesting.

Actually, I'm stating the existence of "antigrav thrusters" is only established for Voyager. Other craft used some other type of thruster configuration that, while powerful and while not exactly environmentally devastating, were clearly not "antigrav" thrusters. The closest we see to this is STV's shuttle landing, though even then thruster action is hinted at by downward-sweeping jet effects from the underisde of the craft (absent from the miniature but present in the set piece).

If we were to use the thrust observed to estimate vessel masses, then we would quite probably have to presume the vessels weigh less than their occupants.

But that would partially defeat the purpose of installing thrusters in the first place if antigravs do 99.9% of the work, wouldn't it?

Antigravs or not, the utility of thrusters is utterly defeated if thrusters alone can only produce one or two m/s acceleration on the starship in question, less still for the often mention but seldom seem "emergency thrusters" in Trek canon. Not that I'm really suggesting any concrete figure, but smaller craft like the bird of prey and--especially--shuttles and support vehicles of various classes--could not realistically have those kinds of masses and still behave the way they do on screen. If antigravs were sufficient to do all that, then they would do the work of thrusters entirely, and ANY starship would be capable of landing or at least hovering.*


* And I half believe they probably should, at the risk of making Star Trek look a little too much like Super Dimension Fortress Macross.

 

[Crazy Eddie]

Newtype Alpha,

I don't know actually, but I do remember in one of the Enterprise Blueprint Threads which were done by Shaw and Cary L. Brown said something to the effect that the Enterprise had about twice the volume of an aircraft-carrier.

I don't know, I somehow doubt that would be true. Actually, I half expect that volume wise they would be very close; Enterprise is a very "skinny" design compared to the average carrier, but it's also "taller" in overall draft. I would actually be very surprised if the TMP refit didn't have considerably less internal volume than a Nimitz.

 

[DSG2k]

Actually, I'm stating the existence of "antigrav thrusters" is only established for Voyager. Other craft used some other type of thruster configuration that, while powerful and while not exactly environmentally devastating, were clearly not "antigrav" thrusters.

If it walks like a duck and quacks like a duck . . .

Compared to the blast of a shuttle launch, no Star Trek landing or take-off event even comes close, no matter the size of the vessel. This has been the case ever since the take-off of "The Galileo Seven"[TOS], in which a nice solid blast effect or plume might've made those big beasties let go of the shuttle instead of requiring additional electrical discharge.

So whether or not the term "antigrav thruster" appeared before, it's clear to me that antigrav technology was in use.

Hell, even Star Trek V's silly boots make this plain, since they have less effect on the surface than even the Bell Rocket Belt (not to mention the fact that Spock uses them to stay airborne with the thrust directed sideways).

The closest we see to this is STV's shuttle landing, though even then thruster action is hinted at by downward-sweeping jet effects from the underisde of the craft (absent from the miniature but present in the set piece).

Don't tell me you're referring to the simple outgassing used to cover the stagehands when they were rolling the shuttle . . . it was already landed.

ANY starship would be capable of landing or at least hovering.

NX-01 flew well over New York at perilously low altitude. But then, making landing legs and a bottom surface and otherwise having the hardware aboard to make the ship landing-worthy is a lot of extra work.

 

[Crazy Eddie]

So whether or not the term "antigrav thruster" appeared before, it's clear to me that antigrav technology was in use.

I'm not so sure. Seems to me some kind of advanced thruster technology would be implied here that provides a very large push for a very small reaction. Impulse engines are all but explicitly implied to work this way even in the TNG manual, although realistically this is just the canonization of the sci-fi fudge factor that invariably follows ALL depictions of space craft no matter the technology base.

Most famously for Star Trek, the sight of the Phoenix launching from a missile silo some two hundred feet away from a tent city and a bar without accidentally blowing everyone away... do you think Phoenix was equipped with antigrav technology?

Hell, even Star Trek V's silly boots make this plain, since they have less effect on the surface than even the Bell Rocket Belt (not to mention the fact that Spock uses them to stay airborne with the thrust directed sideways).

The former doesn't make alot of difference since Spock never got very close to any particular surface. The latter rules out gravity control anyway, for the same reason it rules out simple rockets: if the BOOTS were used as antigravs, Spock wouldn't have been able to hang sideways, he would have flipped over and hung upside down.

If he had an antigrav device it was probably mounted on his belt; the boots themselves would have been merely propulsion units, hence Kirk's "fire the rockets!" in the turboshaft.

And this is where I get to ask you what the mass and volume would be of the Enterprise-A if it was 78 decks high...

Don't tell me you're referring to the simple outgassing used to cover the stagehands when they were rolling the shuttle . . .

I'm not. I'm thinking of Nimbus-III.

ANY starship would be capable of landing or at least hovering.

NX-01 flew well over New York at perilously low altitude.[/quote]
Same question for Phoenix: was NX-01 equipped with antigrav thrusters?

Currently I'm leaning towards the opinion that negating gravity's effects might actually be a feature of warp-drives or at least warp field generators, which might explain why even shuttlecraft have nacelles even when they are not actually warp capable. Those nacelles are pretty huge things to be lugging around if you only ever use them to travel between star systems...

 

[DSG2k]

Your advanced thruster idea is non-Newtonian, which is basically the same thing as antigrav. You have to output enough mass with enough velocity to be Newtonian.

And yes I know about the belt. That doesn't disprove gravity control despite your peculiar claim.

Nimbus III didn't even kick up dust . . . it's more like a gas leak. That's not thrust.

Anyway, will you now acknowledge that your claim of thruster plume proving lower vessel density/mass is false? I don't see where your various statements and attempted counterclaims to every word I say acknowledge that.

 

[DSG2k]

Ah, and:

Most famously for Star Trek, the sight of the Phoenix launching from a missile silo some two hundred feet away from a tent city and a bar without accidentally blowing everyone away... do you think Phoenix was equipped with antigrav technology?

At least she *had* a plume, much of which was released underneath her and then evidently was directed elsewhere (it didn't escape around the Phoenix during launch, so it must've gone somewhere else, much as Shuttle plume is directed to the sides). So no, no antigrav in evidence.

You've actually proven my point even more by the example of a plume that might've been weak. But we don't know that, because save for a sight of lit faces in a bar moments after it emerged from the hole in the ground, we don't know the effect of the launch on the area (e.g. how much vapor and whatnot was in it) after the vehicle launched. So as far as I'm concerned, it was a full plume.

As for the NX, unless you think a ship can float without any visible support and not have some antigravity or mass reduction technology in play . . .

 

[Crazy Eddie]

Your advanced thruster idea is non-Newtonian, which is basically the same thing as antigrav.

Well, no. An antigrav would negate the pull of gravity enough to allow a space craft to maneuver the same way it would in zero gravity. This won't actually provide any motion to the space craft, only static lift to defy local gravity.

This is probably a feature of a ship's inertial dampeners, not "antigrav" per se.

And yes I know about the belt. That doesn't disprove gravity control despite your peculiar claim.

Never claimed it does. I'm saying the BOOTS aren't part of a gravity control system, they're just thrusters. They're obviously powerful enough to provide some pretty impressive accelerations despite their small size and apparent lack of a reactant mass as well as the lack of "ground effect" like you described earlier.

Nimbus III didn't even kick up dust . . . it's more like a gas leak. That's not thrust.

To be sure, it's bad special effects (of the type prevalent in STV, including Spock's boots). But the intention is there.

Anyway, will you now acknowledge that your claim of thruster plume proving lower vessel density/mass is false?

What the hell does thruster plumes have to do with anything? If you go back to my original claim, I described that the EXISTENCE of those thrusters and the way they are used essentially requires a lower mass rating for smaller craft; certainly significantly less than 600 tons for a runabout (or even 24 tons for a small shuttlecraft). That would require either the installation of curiously powerful thrusters or negate the utility of thrusters in the first place.

 

[Crazy Eddie]

as far as I'm concerned, it was a full plume.

If it was the exhaust from any other type of ICBM, it would have been full of corpses.

Which is why I didn't intend this as an example of "weak plume," my actual point is that FX guys in Trek habitually undersell the power of the engines they attempt to depict. It's a little like Gary Seven hanging out on the launch gantry next to a fully fueled Saturn-V minutes before it's supposed to launch; we're supposed to believe he could have survived if that rocket actually launched.

As for the NX, unless you think a ship can float without any visible support and not have some antigravity or mass reduction technology in play . . .

More than likely that's still thruster action at play, just as is explicitly stated in the case of Starfleet shuttlepods.

 

[DSG2k]

Oh good grief. Gary Seven had transporter capability at his command, you know.

I'm sorry, I'm just not seeing where you're not being a Tellarite now.

Your advanced thruster idea is non-Newtonian, which is basically the same thing as antigrav.

Well, no.

Well, yes. If it isn't Newtonian, it's the same magic mumbo-jumbo. There's a difference between useful nitpicking and pointless argument. I mean hell, you then go on to admit that you're just arguing some nuance:

An antigrav would negate the pull of gravity enough to allow a space craft to maneuver the same way it would in zero gravity. This won't actually provide any motion to the space craft, only static lift to defy local gravity.

This is probably a feature of a ship's inertial dampeners, not "antigrav" per se.

So in other words, basically the same thing as antigrav, like I said . . . a non-Newtonian ascent involving no or little thrust in the complete drive system.

And yes I know about the belt. That doesn't disprove gravity control despite your peculiar claim.

Never claimed it does. I'm saying the BOOTS aren't part of a gravity control system, they're just thrusters.

Which I have already showed you, so why keep talking about it? Stop arguing the point. I brought up the boots as yet another counterpoint to your claim that nobody ever thought to combine thrusters and antigrav pre-Voyager. You admit that these rocket boots had an antigrav component as part of the complete system, yet you keep trying to argue.

The details can be different, but the fact remains that we have antigrav in use supporting thrusting objects decades before Voyager. Hell, the damn NX shuttlepods don't kick up enough dust either, even if we assume them to be no more massive than a car.

You can argue the terminology all you like, but the fact remains that these ships do not land by Newtonian thrust, and therefore your claims about masses being too high on my page based on your own presumptions that the Danube can land and take off by thrusters are invalid.

Nimbus III didn't even kick up dust . . . it's more like a gas leak. That's not thrust.

To be sure, it's bad special effects (of the type prevalent in STV, including Spock's boots). But the intention is there.

Bull. I can just as easily say it was "intended" to be simple outgassing, so "ha!".

Don't try to take this into some "intention" crap. I know that's the sort of hocus-pocus some of the folks at TrekBBS like to pull when they can't prove their case, but I won't stand for it.

If it was the exhaust from any other type of ICBM, it would have been full of corpses.

Bull. I wouldn't want to be under it, but there's no evidence that the modified rocket would be lethal at that location, and indeed we can pretty well prove that it wasn't by virtue of the movie.

We can chalk this up to tricks of the throttle and plume redirect, or what-have-you, but the fact remains that this is presented as a rocket, unlike Trek ships taking off, which are most certainly not presented as anything remotely resembling a rocket.

Thus your claim about masses is disproved yet again.

Anyway, will you now acknowledge that your claim of thruster plume proving lower vessel density/mass is false?

What the hell does thruster plumes have to do with anything? If you go back to my original claim, I described that the EXISTENCE of those thrusters and the way they are used essentially requires a lower mass rating for smaller craft; certainly significantly less than 600 tons for a runabout (or even 24 tons for a small shuttlecraft). That would require either the installation of curiously powerful thrusters or negate the utility of thrusters in the first place.

And I say you're dead wrong, because you're claiming a lack of antigravity technology (or technology of similar effect, whether you want to nitpick and call it inertial dampening or what-have-you, it's the same bloody non-Newtonian magic) in Star Trek pre-Voyager when I've gone and shown you that it's always been there.

Thus, your claim that the thruster effects show lesser mass is wrong.

The shows give stated masses. You are arguing against them based on your own presumptions about creator intent without evidence, your own presumptions about the use of thrusters to lift a Danube to orbit without evidence, and your own fallacious personal incredulity, which is not an argument.

Your belief or consent is not required, and your incessantly argumentative behavior makes it clear it will not be obtained. I've been very patient as you've tried every conceivable method to argue against the masses given in the show, but your pointless argumentation against every single utterance makes it clear you are simply being pedantic and not engaged in any honest inquiry. So, stop wasting my time.

The masses and densities stand, as does my page.

To any who are reading, my apologies for NewType's behavior, and my own in response. Please know that if you have any honest questions about the Volumetrics page or note any real flaw, you are cordially invited to ask away.

 

[DSG2k]

The Delta Flyer is now added to the Volumetrics page, and the Runabout is updated with the superior model found at the link. This results in a 5.4% increase for the Danube's volume compared to the inferior (less accurate) model, from 542 to 571 cubic meters.

Given the densities described for the Delta Flyer and which we can also presume for the Danube, their masses would come to 380 and 640 tonnes, respectively.

 

[CuttingEdge100]

That sounds a bit excessive... 380 to 640 tonnes?

 

[DSG2k]

Why excessive? Voyager was repeatedly said to be a 700,000 tonne starship, necessitating by virtue of her volume a density of over 1100 kilograms (1.1 tonnes) per cubic meter.

In "Thirty Days"[VOY5] the Delta Flyer has to offload mass in order to float to the surface of an ocean, where the excessive water depth calculates to a rough minimum water density of about 1.1 to 1.3 tonnes per cubic meter. So, whatever Delta Flyer's volume was, it seemed her density matched Voyager's.

All I did with the update above was finally get a volume reading for the Delta Flyer, enabling a mass estimate of 380 tonnes by simple mathematics. Assuming the same density for the runabouts, then they'd come to 640 tonnes.

It's just information from the shows.

 

[Crazy Eddie]

That sounds a bit excessive... 380 to 640 tonnes?

Yeah, for a craft that size even 64 tons would be a bit much (that would weigh as much as an Abrams MBT). But again, considering the heaviest thing in most starships is probably a set of ultra-dense warp coils, I figure the safer bet for small craft (anything smaller than a Captain's Yacht) would be to scale down those estimates by about a factor of ten.

 

[DSG2k]

No, newtype. Just stop.

1. These are the masses and densities and volumes given in the show. It would be one thing if you wanted to accept the Star Trek data but also discuss real-world things for comparison in a gee-whiz way, but you keep trying to reject the Star Trek data and my estimates from it in favor of your own personal view of real-world things. You may ignore it for whatever whimsical reason you choose, but it's Star Trek's presentation of itself that my page is about, so saying I need to change my estimates is absurd and a waste of both our times.

2. I bolded the above because even real-world objects don't support your view, yet you ignore this fact. Specifically, the vehicle I already told you about:

The Caterpillar 797B is smaller than a runabout.

The runabout takes up a parking spot 23.1 by 13.7 meters in size.
The Cat 797B takes up a parking spot 14.5 by 9.8 meters in size.
The runabout is 5.4 meters tall. The 797 is 7.6 meters tall.

So yes it's 40% taller, but it's 45% the area. The 797B is not exactly a solid cube, so don't go pretending that it is. It's basically an engine, frame, axles, a bowl shape, and a whole lot of empty space. This SketchUp model gives it a volume (including the empty space of tires) of 187 cubic meters.

Empty, the thing weighs 254 tonnes. That's a density of 1350 kg/m^3 . . . denser than Voyager, or about the high-end density I found for the Delta Flyer!

Now, do you really mean to tell me that you don't think a Danube Class starship might weigh a wee bit more than a modern-day dump truck? I know the thing's built to carry a bunch of dirt and rock, but don't you think a starship might need to be built to similar tolerances? A starship capable of tangling with Jem'Hadar fighters and megaton-scale weaponry, a starship that can survive the extraordinary acceleration of its own impulse engines, leaping to warp speed, crashing into planets, and even wrangling with a tractor beam at warp? A starship built by the same folks who built the Delta Flyer, which smashed into a planet and buried itself three kilometers into rock? A starship built by the same people who fought and won against the Jem'Hadar, whose attack ships can suffer an uncontrolled de-orbit and crash into a planet's surface, burying themselves dozens of meters into rock, and can then be pulled out intact with no obvious damage?

You really don't think that tritanium and duranium structures capable of all these things might have density on par with a modern-day steel dump truck? Are you nuts?

Maybe so, because you want the runabout to weigh no more than a battle tank that's tiny by comparison, perhaps a third of the size. Hell, the runabout should be tougher than a tank. And guess what? The Abrams volume is 51.7 cubic meters, which given a mass of 61.3 tonnes means that even the Abrams tank matches the density of Voyager and the Delta Flyer.

Newtype, I realize that your devotion to your newfound peculiar cause of heckling my page and rejecting the correct masses will lead you to argue the point, but can't you maybe, just maybe, accept for a moment that perhaps the ships really might be dense, and that you yourself are wrong, and that it's time to stop trolling the thread?

 

[Crazy Eddie]

Sure.

Then compare with the Soviet TKS spacecraft with a volume of 55 cubic meters and a empty mass of 18 tons. For that matter, the ISS with a volume of 410 cubic meters (including non-habitable volume) and a mass of 344 tons.

These are both spacecraft with considerably lower densities than the D-flyer OR voyager, almost half that in the case of TKS. The space shuttle's density comes out to between 450 and 800kg/m^3 depending on the model (modeled without the bay doors, it becomes alot lower).

And since I brought it up before: the Los Angeles class submarine has a volume of approximately 24,000m^3. Its actual displacement is close to 7000 tons. Applying your formulas, however, would net a displacement closer to 30,000 tons. This suggests to me that overall volume measured at the external surface can't really tell you anything about the overall density, especially if these craft contain a large amount of hollow space in their interiors (though I agree with the application in principle, but there seems to be something missing from your analysis).

So at least for small craft with small warp nacelles, a lower mass figure seems more logical, where the higher figure for starships can be explained by unobtanium components like warp coils and the like.

Newtype, I realize that your devotion to your newfound peculiar cause of heckling my page and rejecting the correct masses will lead you to argue the point, but can't you maybe, just maybe, accept for a moment that perhaps the ships really might be dense, and that you yourself are wrong, and that it's time to stop trolling the thread?

If you didn't want honest opinions about your web page you shouldn't have posted it here in the first place. If you want that kind of attention, then don't go callin the wahmbulance whenever some simpleton on a message board dares to disagree with you.

 

[blssdwlf]

Sure.

Then compare with the Soviet TKS spacecraft with a volume of 55 cubic meters and a empty mass of 18 tons. For that matter, the ISS with a volume of 410 cubic meters (including non-habitable volume) and a mass of 344 tons.

These are both spacecraft with considerably lower densities than the D-flyer OR voyager, almost half that in the case of TKS. The space shuttle's density comes out to between 450 and 800kg/m^3 depending on the model (modeled without the bay doors, it becomes alot lower).

I don't think they are comparable since the TKS, shuttle and ISS are not designed and shielded for deep space travel (and fictionally: warp stress, impulse stress, etc.) I would imagine the density to potentially go up if you factor those things in.

And since I brought it up before: the Los Angeles class submarine has a volume of approximately 24,000m^3. Its actual displacement is close to 7000 tons. Applying your formulas, however, would net a displacement closer to 30,000 tons.

I went and looked DSG2K's site. Where does he say that the LA class sub should be displacing 30,000 tons? It looked more like he derived density from measuring volume and dialogue-stated mass figures and then applied it to "like" technology spacecraft. That seems reasonable to me.

If he used the same method for say a submarine, then I would think the same would be workable to take the density of an LA class sub and apply it to another same generation submarine to estimate displacement.

So at least for small craft with small warp nacelles, a lower mass figure seems more logical, where the higher figure for starships can be explained by unobtanium components like warp coils and the like.

That seems logical. A small craft (like a shuttle but not like a 1 seat fighter) usually has a larger percentage of interior space vs structural/mechanical equipment than say a starship (in general).

But how much lower? It is hard to judge given that there are warp engines, m/ar reactors, batteries, duranium (or whatever) hulls, etc involved and no numerical reference point (like dialogue) to draw any conclusions for small craft.

 

[DSG2k]

What the hell, I'll feed the troll one more time.

1. Applying from modern anything is a conceit anyway. Subs and ships are limited by bouyancy concerns, aircraft must be able to generate sufficient lift via aerodynamics (not to mention fuel), modern spacecraft have to be launched by way of modern rocket technology with all of its constraints, and tanks have to contend with transportability and ground pressure on things like mud and roads.

Trek vessels have virtually none of these concerns . . . they have concerns all their own, like resisting city-destroying firepower and all the other things I said in my last post. The only one of those that has squat to do with Trek vessels is the question of ground pressure given what we've seen of unpowered ships and shuttles (i.e. crashed and what-have-you). But as noted previously, that's not a problem, given that tanks and so on feature densities and ground pressures equivalent to Voyager and the Delta Flyer.

And all of the modern examples are made with modern materials, unlike Trek ships.

2. So while applying from modern things to Trek is silly, so too is your foolish attempt to claim that we should apply from Trek to modern things as some sort of test. My page is quite clearly based on taking the statements from Trek and applying them to Trek ships. There is no logic in attempting to apply them elsewhere, and your efforts at doing so as if such maneuvers represent some sort of disproof only make you look silly.

3. As for the claim that small vessels should weigh less, that's just a desperate attempt to continue arguing. The Delta Flyer is a small vessel, hardly different than a shuttle in interior space versus total volume, and not terribly much bigger than a shuttle anyway. And yet when presented with the Delta Flyer, itself some 1,863 times smaller than Voyager, you seek to claim that although they both have similar densities, somehow a fighter (five times larger than the Delta Flyer) will suddenly be built out of cardboard by comparison.

In short, you're not even making any sense.

4. You're not giving honest opinions about my webpage. You are trolling.

If you were simply interested in giving an honest, critical opinion, you might simply note that you personally don't agree with the canon densities, but that (a) they are canon and (b) my page deals with them correctly. In other words, you would note that I have a premise and I follow it to its conclusion correctly.

Now, if by chance I had some error, be it in the form of calculation or logic from the premise, or even something wrong with the premise, then you'd have an opening for constructive criticism. (Say, if I flubbed some volume estimate or some point of mathematics or some detail from the show.)

However, you're not doing anything like that.

Instead, you're claiming that my page is wrong because in your baseless opinion, the canon masses are too high, and that I should change my page to match your baseless opinion, because my page fails to pass a test based on your baseless opinion. Methinks therefore that you've been watching too much House, given your avatar.

The simple fact is that your opinion is not even internally consistent, it is not consistent with modern objects, it is not consistent with the information from the show, and, again, you're basically just trolling this thread. Other people might want to have an interesting discussion about Star Trek vessel volumes and densities that (shock!) come from Star Trek, but your whining and complaining that I dare go with the canon values is getting in the way of that.

So here's my suggestion: I have shared the method (and it's even free!) and have shared my volume results. So if you want to have a page detailing your fanciful densities originating from your posterior, go make your own page and stop making demands about mine which will never be met.

And when you do, I promise not to troll it by whining in every post that you should be using canon densities. Wouldn't want anyone to have to put up with someone acting like you, after all.

 

[Crazy Eddie]

Sure.

Then compare with the Soviet TKS spacecraft with a volume of 55 cubic meters and a empty mass of 18 tons. For that matter, the ISS with a volume of 410 cubic meters (including non-habitable volume) and a mass of 344 tons.

These are both spacecraft with considerably lower densities than the D-flyer OR voyager, almost half that in the case of TKS. The space shuttle's density comes out to between 450 and 800kg/m^3 depending on the model (modeled without the bay doors, it becomes alot lower).

I don't think they are comparable since the TKS, shuttle and ISS are not designed and shielded for deep space travel (and fictionally: warp stress, impulse stress, etc.) I would imagine the density to potentially go up if you factor those things in.

Possibly (which is why I think it still works for larger spacecraft like starships). That stronger materials do exist, though, and the existence of things like inertial dampeners and structural integrity fields can't be ignored either.

Truly, modern spacecraft would be rather flimsy by comparison (see Ares-V vs. Delta Flyer) but I'm not so sure this has as much to do with the density of hull materials as other things.

I went and looked DSG2K's site. Where does he say that the LA class sub should be displacing 30,000 tons?

You're late to this thread, but a few pages ago I mentioned that it would be interesting to use DSG2K's formulas to apply to other existing craft whose volumes are known. Submarines would be a good bet because they are also designed to withstand prolonged extreme pressure and stress, so since DSG2K declined to do so, I ran the numbers myself.

So at least for small craft with small warp nacelles, a lower mass figure seems more logical, where the higher figure for starships can be explained by unobtanium components like warp coils and the like.

That seems logical. A small craft (like a shuttle but not like a 1 seat fighter) usually has a larger percentage of interior space vs structural/mechanical equipment than say a starship (in general).

But how much lower? It is hard to judge given that there are warp engines, m/ar reactors, batteries, duranium (or whatever) hulls, etc involved and no numerical reference point (like dialogue) to draw any conclusions for small craft.

Well, we can see the interior of things like the Type-6 and Type-8s that are almost entirely empty space with some engines attached. These I would expect to be on the extreme light end of the spectrum. The Type-7 has a warp core in its aft compartment and some extra bulkhead space, so I would expect it to be a BIT heavier.

The thing is, I still think the densest thing on any starship is going to be the nacelles. Even in a single-seat fighter, most of the fuselage is empty space anyway (just because it isn't habitable doesn't mean it's a solid piece of iron; it's usually structural ribbing, avionics bays, probably some fuel tanks). Warp nacelles are supposed to be made out of verterium cortenide, though, which even the TNG manual implies is supposed to be ungodly heavy. The way the volume works out, a shuttlecraft with 12 tire-sized warp nacelles might concentrate, say, 40% of its overall mass in those coils; a starship might be closer to 80%, especially since the larger ship's drive coils are designed to handle higher speeds for longer periods of time.