19 June 2012

Size Matters...when it comes to starships that is

Over at io9.com, wordpress blogger Invader Xen (his astronomy blog http://supernovacondensate.net/) created a size comparison of the Federation Enterprise and real-world space vehicles, and this is his imagine, and quite good work...visit his blog, also very good.
Size with starships is one of those things that is hard to judge for us sci-fi writers, often we, especially for RPGs, make these space warships massive. Many years ago, it was not uncome for me to design warships in the battlecruiser class being 800-1000 meters.


  1. http://www.merzo.net/ - size comparisons of dozens of sci-fi ships and real world vehicles viable in different scales.

  2. That is one hell of an impressive site! A big thank you Gotthammer! I am making this a MSF link...impressive...most impressive!

  3. Starship Dimensions is a really impressive site- I was going to tell you about it, but Gotthammer mentioned it first. I've found it is very hard to tell the difference between a small starship and a giant cruiser without visual references- and space is often devoid of any useful references. 800-1000 meters, that is about a kilometer long- I hope your space troops have brought bicycles, they will need them to get from one end of the ship to another!! Hmmm... maybe that was the real use of Veritech cycles- getting from one end of a kilometer long space cruiser to another.

    The size of the craft we can build depends on how strong the materials we have are and how much building material we can put in space. If we are building a stationary space station or gargantuan space colony, than size does not matter. If we are building a ship, size does matter, because the ship will experience accelerations and must be strong enough to support its own weight. The strength of material is defined by the load-bearing area, which goes up by the square because it is an area. Mass, on the other hand, goes up by the cube because it depends on the volume of structural material in the ship. Therefore, if the ship is too big, its mass will be to great for its strength to support under acceleration or when landing on a planet, and your spaceship will be crushed.

    I don't know what exactly are the limitations on ship size with conceivable technology, but ten-thousand ton spaceships were designed during Project Orion- and intended for launch from the ground!! We should be able to do better with future or even modern materials. The problem is putting the building materials we need in orbit. Perhaps materials might be launched from the Moon with electromagnetic launchers, or captive asteroids could be mined for raw materials. Such large ships will probably have to be built in orbit.

    Without antigravity generators or reactionless field drives the only way a really big spaceship is getting off the ground is with a huge rocket that will make the Saturn-5 look like a bottle rocket. It might not matter if it is off somewhere in the middle of a desert or the ocean, but I would not try this near an inhabited city. Then again, there are the Cole-Helios nuclear pulse jets. Go to http://up-ship.com/blog/?p=5353 and scroll down the nuclear pulse jets, and the Aldebaran in particular. Nuclear pulse ships tend to be BIG, which is good, since I like the idea of fleets of huge spacecraft flying to the ends of the universe.

    If we update the Cole-Helios concept to fusion-powered rockets expelling super-heated plasma in space and switch to air-breathing plasma-shock expansion mode in an atmosphere, we might get a sizable Macross cruiser into space, especially with the help of antigravity pods. Now all we need is a hyperspace-fold engine...

    Christopher Phoenix

  4. Well, the size is quite important and somehow difficult to get right. The most important question is, IMHO, the role of the ship. You need a troopship? Fine, it has to be big. What type of unit does it carry? Do the troops have vehicles with them? Do they wear APS? Do you have ships that transport men planetside or does the troopship itself fulfill the role? After that, what about the propulsion? Then and only then can you start asking how big can it get.

    Greetings, Chris

  5. Size and the role do matter, and I think not enough of sci-fi creators understand the size of the ships and interior dimensions of a ship, like the SDF-1's belly taking in 70,000 civilians and constructing Macross.
    One of the most realistic designed interstellar ships, the ISV Venture Star from AVATAR is 1646 meters in length, due to the propulsion system, and the crew modules are very small in comparison to the M/AM drive. Of course, the Venture Star is a sleeper and not the QE2.
    Chris and Mr. Phoenix have it right, and based on the comments here, FWS will be writting a blogpost on the size of starships of sci-fi. Thanks for the idea!

  6. Annoying, isn't it, how so many of the best ideas are those which have been coloured red. Skylon ofcourse is a very good idea, but sadly not yet operational.

    A key thing to consider here is that the size of the ships, especially skylon, is due to the fuel they must carry. current chemical fuels having such poor exhaust velocity that mass ratios as high as 15 are sometimes needed. It is another good argument for nuclear powered spacecraft, the nuclear lightbulb would probably be best for launch systems. Something of it's type might well make shuttles of the kind we see in avatar (the shuttle was the best bit for me, not that the rest was bad) a reality.

  7. with that size and (possibly) heavy mass, i just wondering how they craft that spaceship. the one possible thing probably the spaceship are crafted in space stations, not on earth like in the movies. and space stations have something like skylift to transport material from earth to space stations. well it's different story if they craft anti gravity device though

  8. I pay careful attention to size, square-cube law, thrust, and intended mission. The smaller vessels are propelled by nuclear pulse drives capable of multiple gees of thrust because they have less mass relative to the cross-sectional area of their structural members, but exhaust velocities of "only" 12km/s to 30 km/s. These are mostly dropships, but a few high-thrust battlecruisers show up in the novel's climax.

    The largest vessels are starships pushed by fusion-powered ion engines, producing exchaust velocities of near the speed of light but with only milligees of thrust. They ferry the smaller vessels into the local space for battle but tend to stay far away from the action.