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Old November 5 2013, 04:36 PM   #1
Chuck4
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Density of star ships

TOS and TMP enterprise were suppose to be around 300 metered long, and mass 300,000 metric tons. This would make it approximately as long as an large aircraft carrier but three times as massive. I haven't actually worked out the volume of the star ship, but eyeballing it tells me it's a pretty space inefficient design, meaning it has a lot of dimension and surface ares for not much interior volume. The primary hull is on average maybe 3 decks thick. The secondary hull has at most 1/8 the volumn of an aircraft carrier hull. The hull of a large aircraft carrier almost certainly has much more interior volume in total than the TOS enterprise.

So, this means overall, the enterprise is an extraordinarily dense structure, far denser than modern ships, planes, or submarines. Possibly 3-6 times denser. Enterprise is certainly denser than water and would sink like a stone if it had to ditch.

Since most of the enterprise's primary and seconary hills are empty space just like shipand assuming 2 centuries of progress in material science would allow the ship's structural weight to stay under control, this suggests most of the ship's mass must be in those two big engine nacelles.

What do you think?
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Old November 5 2013, 04:45 PM   #2
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Re: Density of star ships

I think a lot of people have placed the bulk of a ship's weight in the nacelles with the idea that the warp coils, antimatter pods, or whatever you think is in there are extremely heavy. In that capacity, the nacelle struts are not so much supporting the nacelles as attaching the rest of the ship to them.
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Old November 5 2013, 05:16 PM   #3
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Re: Density of star ships

There's not a lot that supports the "300,000" metric ton figure other than fanon. The numbers more usually bandied about outside of that are closer to a million metric tons. Usually in the 700,000-1,000,000 metric ton range. The internal volume of the TOS Ent is about 215,000 cubic meters.
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Old November 5 2013, 05:18 PM   #4
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Re: Density of star ships

Indeed I'd also agree that the Nacelles are likely by far the "heaviest" part of the ship. I get the feeling that those warp coils are ultra dense. I also get that feeling that they are made that way on purpose as to last longer.
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Old November 5 2013, 05:39 PM   #5
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Re: Density of star ships

I'm not aware of any canonical references that quote the mass of any starship aloud. If there are any, I'd sure like to know what episodes they're in. Ditto for length figures and other size measurements.

Size is easier to estimate than mass, because we have geometry at our disposal, and objects of known size (i.e. people) to make comparisons.

To estimate mass, we have to be more indirect. Starships don't gravitationally disrupt the planetary systems they pass through, so they can't be too heavy. Additionally, those that land on planet surfaces (e.g., Bounty and Voyager) can't be so heavy that they sink into the ground.

For reference, the displacement of the real-world aircraft carrier USS Enterprise (CVN-65) is on the order of 95,000 tons, nearly one-third of the quoted 300,000 metric tons for the starship. Given what the starship does, I've always thought that therefore that's just too light a figure for the starship's mass. How heavy it could get before it started interfering with the orbits of planetary satellites, I don't know, but I'd imagine it to be as heavy as it could get without being disruptive (when all its power systems are turned off).

I agree that the nacelles are probably the densest parts.

Just my two cents.
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Old November 5 2013, 10:20 PM   #6
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Re: Density of star ships

CorporalCaptain wrote: View Post
I'm not aware of any canonical references that quote the mass of any starship aloud. If there are any, I'd sure like to know what episodes they're in.
Scotty in Mudd's Women "almost a million gross tons".
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Old November 5 2013, 10:29 PM   #7
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Re: Density of star ships

One thing to remember is that ocean-going vessels must by design have a density that is less than that of surface seawater: starships do not.
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Old November 5 2013, 10:32 PM   #8
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Re: Density of star ships

Scotty mentions the ship's about a million gross tons (probably meaning long ton here) in "Mudd's Women", while Voyager is noted as being "15 decks thick, and 700,000 metric tons" several times in the series. (There's a little bit of a comparison and analysis here: http://www.trekbbs.com/showthread.php?t=227710 )

We're talking about a hull that needs to withstand extremes of temperature and kinetic stresses that would tear anything built to CVN-65's standards to pieces. The density's going to be higher as a matter of course.
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Old November 6 2013, 12:32 AM   #9
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Re: Density of star ships

Nob Akimoto wrote: View Post
Scotty mentions the ship's about a million gross tons (probably meaning long ton here) in "Mudd's Women", while Voyager is noted as being "15 decks thick, and 700,000 metric tons" several times in the series.
Ah, thanks!
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Old November 6 2013, 12:45 AM   #10
Chuck4
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Re: Density of star ships

If enterprise has a volume of 215000 cubic meters and a mass of a million tons, that means the ship is denser overall then if it were made of solid titanium without any cavities inside.

If let's say 3/4 of that mass is in those nacelles, then those nacelles would have to be far denser than solid lead, gold, or uranium, amongst the densest materials under normal temperature and pressure known to science.

This suggests the script writers didn't think about what they were talking about, or the enterprise must have quite an amount of exotic ultradense substances as yet completely unknown to science onboard.

Now very approximately, TOS and TMP enterprise is roughly the same size as USS Nimitz, or about 4 times the size of the largest modern cargo plane, the an-225.

The Nimitz weigh 100,000 ton full load, so it's structural weight would roughly be in the 50,000-70,000 ton range, sans reactor, store, planes, crew, aviation fuel, munition. An-225 weigh about 250 tons empty. Scale up by a factor of 4 would make it 64 times heavier, or roughly 18,000 tons.

I think given 2 centuries of advancements in material science, with new thinks like structural integrity fields, etc, it is reasonable to suppose star ship builders should be able to keep structural weights of the enterprise very broadly in line with the weights of these 20 century structures of comparable size. So 20,000 - 70,000 ton would seem a fair and reasonable estimate for how much enterprise's structure ought to weigh. Double that for doubt, I think enterprise's structure would weight 140,000 ton, tops.

In light of this, a total weight or mass of 300,000 tons would seem much more reasonable. In this case, enterprise would already be far denser than water and would sink like a stone.

1,000,000 ton would just be very hard to support, unless we posit somewhere on the ship these are 800,000 tons of some truly exotically dense material.

If these is a small black hole somewhere in the ship's innards to help power it, then I would believe the figure of 1,000,000 tons. Otherwise the ship wouldn't be that heavy if it were cast in solid metal.

Last edited by Chuck4; November 6 2013 at 01:21 AM.
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Old November 6 2013, 02:12 AM   #11
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Re: Density of star ships

CorporalCaptain wrote: View Post
Ah, thanks!
You're welcome.
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Old November 6 2013, 02:25 AM   #12
Nob Akimoto
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Re: Density of star ships

A 210,000 m* ship at a million metric tons is only a density of 5,000 kg/m. That's dense, but it's not unbelievably dense.

A more useful metric is probably taking the surface area of the ship and multiplying it by a small amount to get a overall "outer hull" volume. Here we're talking about 60,000 m. With a 2m thick outer hull, we'd fudge it and say there's 120000m of hull plating volume. That's a density requirement of about anywhere from 5,000 - 8,000 kg/m depending on how we define "nearly a million gross tons of ship". Presumably stuff like duranium, rodinium or trititanium is going to be much denser than titanium, and probably closer to stuff like tungsten(19,000 kg/m) or nickel (8,900 kg/m).

If we made it so half of the ship is made up of some sort of carbon molecule similar to diamond, and the other half out of a dense metal, then somewhere in the high 6 figures would make sense for a starship's overall mass.
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Old November 6 2013, 02:41 AM   #13
Chuck4
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Re: Density of star ships

A 2 meter thick hull would be difficult to justify given the large number of windows.
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Old November 6 2013, 02:51 AM   #14
Chuck4
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Re: Density of star ships

A 2 meter thick hull would be difficult to justify given the large number of windows.

Also, if the ship indeed need a dense hull 2 meters thick, resulting in an outer shell that is a big part of the ship's mass, then any decent engineer would have economized on both total weight and the use the this dense material by giving the ship a more volume efficient shape, in other words, adopt a shape that had less surface area for a given amount internal volume.

As it is enterprise is hardly shape that maximize internal volume for a given surface area and shell weight. It is a shape that only makes sense if structure itself is cheap, light and very strong.
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Old November 6 2013, 01:40 PM   #15
Masao
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Re: Density of star ships

I've always disregard the "million gross tons" figure for Enterprise. Sometimes common sense should prevail over onscreen evidence. As has been discussed in this forum before, "gross ton" can be a unit of weight (the same as "long ton") or can be a unit of volume. If we use Nob's figure of 215,000 m^3 for volume and a commonly quoted displacement of 190,000 metric tons, we get an overall density of about 0.9 metric tons per cubic meter, which is a bit less than water. Of course, that's an overall figure, and some parts of the ship are denser and some are less dense. I've always thought that advances in material science would lead to starships being less dense (lighter yet stronger) then present day ships.

Voyager/Intrepid has a volume of 626,000 m^3, so with a weight of 700 kmt, it has a density a bit higher than water but in the same ball park.
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Last edited by Masao; November 6 2013 at 01:58 PM. Reason: More info
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