Designing a spaceship (detailing - pg 6)

I totally agree with you Nyrath about windows. They aren’t needed if there is nothing to look at. Plus, if you cannot get close to the window, it’s even more worthless.

Thanks! And do not let the others discourage you from working out the technical details, artist types get nervous when numbers and mathematics are mentioned. :wink: You are to be congratulated for taking the time to do the math.

This might be a bit generous. I do not know how many crewmembers your ship has, but typically on warships each crewmember is alloted only 10 cubic meters. At a rough guess, figure about 2 cubic m of food-water-air per crewmember per day. Less if you are using a closed ecological system (algae tank).

I haven’t run the numbers, but it seems a little low. If you have directed energy weapons you may need more. And an auxiliary fission reactor or something to “jump start” the fusion reactor.

It might be more efficient to use an arc jet, where the propellant is heated by an electric arc. For non-combat attitude adjustment, you might be able to use super-efficient ion drive thrusters. They are efficient but slow and weak.

I have extremely roughly computed the volume and the result was about 1,5 mil. cu m. so 100 000 cu m is only small fraction, much more is needed for tanks. Even if total volume was 1 000 000 cu m (the resulting density would be similar to liquid hydrogen), the crew compartments aren’t majority. Considering they might be locked there for few years, this generosity is in place: on Earth, you can get outside (well not submarines), but in space extra room is surely good for the crew. There will be about 1000 people aboard, for longer missions maybe less.

An APU (in space a fission reactor for energy needed to start and operate the ship while not using main engines) is a sure thing, I guess. About the main fusion reactor, if it gives 450 GW, 300 GW are needed to develop thrust and 150 GW is heat, then some fraction (say, in best conditions 80 GW is radiated away in main high-temp radiators) the rest 70 GW can be then used to make electricity (with efficiency of 80%, what is really good) and the rest 14 GW again radiated away in second pass. So, normally there is 56 GW of energy to power the and magnets in engines and reactor and to power the fusion. In combat, more electricity can be made, as less energy is radiated away in first pass. I think this is a good system, only to take care of the heat from shooting…

Yes, I check you on about 300 GW for thrust, the other figures look reasonable to me.

But now at the risk of annoying you, I must bring up the delicate question of which way is “down” on a spacecraft.

Just had a ride in a friend’s Prius. There’s a monitor on the dashboard, and a video camera somewhere pointing backwards, so when the car was in reverse, the monitor showed a view of what was behind the car. The view was larger and clearer than the view in the rear view mirror. There are your windows. Surface mounted video cameras, connected to viewscreens inside the ship where ever you want to put them. Technology’s available today.

i would l;ike a monitar tjhere

oh and i hate pimp my ride they do stupid shit like put a huge tv in the trunk how gay

For everybody impatient to see some meshes I have something interesting here and here.

It is a mesh used to compute volume, so it has nothing to do with final model. I have there two positions of radiators, which one is better? When talking about radiators, do you think 3 000 t of coolant is enough to transport 150 GJ each second?

The volume (computed with a superb script) can be seen in the images (I used scale 10 times bigger, so multiply the volume by 1000 and area by 200, because the surfaces are double-sided). The volume_in is the total volume in inner hull, there is 2-3 m wide gap between the hulls. Cube (free fall) and Cylinder (artificial gravity) represents the crew compartments.

I’d suggest to stop calculating how long it would take to accelerate to 400 km/s and start modeling
Well, I won’t start until I’m satisfied with the design. The “quarter-realism” is in place, such a big and powerful ship operating in space has really big power, hardly imaginable for most people (including me). According to wikipedia, 300 GW is electrical power produced in all nuclear plants in world. Can you imagine putting 400 plants into Empire State Building?

I’m afraid that miniature cameras aren’t that same as windows in appearance from outside. Sure, this is easily imaginable way how to let the crew see outside, but for an outside observer it doesn’t give any clue where the crew is located, or how big the ship is.

But now at the risk of annoying you, I must bring up the delicate question of which way is “down” on a spacecraft.
Can human feel acceleration of 1/400 g (in best case, when the ship is almost empty)? I think this is so small, that there must be artificially generated gravity (well, centrifugal force).

Excellent. I was jealous of Lightwave’s AreaVolume script, until somebody wrote an equivalent script for Blender. It really helps calculating the volume of irregular objects.

You are doing an incredible job here. You might consider writing a tutorial on using Blender to design scientifically accurate spacecraft. If you did, I’d be happy to host it on my website.

AFAIK, the main factors of radiators is to ensure that the surfaces cannot “see” another radiator or a hull section, and to provide sufficient support under thrust or maneuvering. The fact that they are pathetically vulnerable to hostile weapons fire is a point of concern for warship designers. Your question about how much coolant flow is enough is a good one, I wish I had an answer. I’ll have to ask around.

Good point. Though even with 1/400 g, a dropped object will take about a minute to fall to the floor, but it will eventually find its way there.

Centrifuges are a problem, since they tend to have a huge diameter. It helps if you assume a trained crew that can cope with the higher RPM without nausea, this reduces the diameter quite a bit. The spin axis is generally coincident with the thrust axis.

now i dont mean this as an insult to u or anyone else, but all these calculations are sort of taking the fun out of it. yes we artists here at blender artist are afraid of numbers and math(at least i am). thats why im an artist. to create a good piece of art (if that is ur end goal) than u need to sacrifice some practicality and focus on design(eg. windows) i dont care what the engine can push, just so long as the exhaust looks cool. I dont care about the crew courters, because my computer would slap me in the face if i tried to model an interior and and exterior in the same blend file. personally i would focus on making a reall cool looking ship(s) to have fight scenes, space stations, and planets.

just my two cents. ill continue watching this thread, but if u want me to not critique ur design choices because ur focus is on practicality then thats fine.

i just wanted to put this out there, so u didnt do all this work and people dont appreciate the fact that its been mathematically proven to work. i know id be dissappointed if it turned out ugly(which i dont think urs will, its a very cool design. i especially like some of ur original sketches, the one one with flat bottom looks really intimidating)

peace

zbirdboy:
Look at the physical and engineering limitations as design feature. A cool looking thing might be not possible, but not in every case. When creating, designing, imagining, the initial impulse comes from certain feeling or vision. If you add also a tiny bit (because what I’m doing is far far away from engineering) of scientific believability, the result will have more depth. The real-world limitations aren’t that limiting to not permit visually appealing and pleasant design. Yes, it is an extra work, but I think it is worth it.

In case of starships, the figures help with realizing how small people are. I think that having a ship jumping from star to star is very shallow, the complexity and diversity of our close (in astronomical terms) neighbourhood is lost. You can post your critique, think that people doesn’t like maths doesn’t discourage me (I don’t like it that much either). But the physics part is interesting, I learn a lot about the world I live in a lot by this.

Nyrath:
I use Yorik’s script (on 2nd page): http://blenderartists.org/forum/showthread.php?t=84827

The tutorial is a possibility, but writing a tutorial how to imegine things? Although in Blender, there are some useful tools that can be used to help with some relations, computations, that is a good subject for a tut.

The radiators are similar to big sails, they can be rotated around one axis. I want to have them anchored by tethers (but those had to be quite strong at high temperature of 2500 K). Also, it is vital that the pipes where the coolant flows are divided into many sectors, that can be closed in case of rupture. The radiator material itself (a highly thermal conductive and of high emissivity, capable to sustain high temperature, yet light enough) is mystery for me. The sail design is be strong and light enough to survive the low acceleration, and moveable to shield it in battle. Now, I think I’ll make a big, single vertical sail instead of two, which would eliminate the occlusion of other parts.

I worked a bit about the coolants, and about 600 tons of lithium each second can absorb 150 GJ (but, I don’t know how long will the transfer last, what area is needed for best heat transfer, and used only value of thermal capacity at standard atmosphere, but it is good start). These 600 t have to circulate in 5 seconds trough 200 m long radiator, while delta t is 700 K. So this seems to be very limiting, together with fact, that the radiators won’t give away desired amount of energy. So, the engine will need more power to operate, so less heat will be needed to radiate, but the heat transfer problem remains. Or something more complex will be there, using parts of less stressed of ship’s structure to carry heat energy to produce electricity.

I haven’t played with centrifuge params, but is is 70 m in diameter, and the force doesn’t have to be 1g, maybe 2/3 can be enough. But the constant acceleration can cause some problems, so the crew won’t spin all the time.

My vision of deep space (or interplanetary) war (if any will be) is, when ships know of each other, the distances and time before the combat begins is long, that it will look more like sailing ships trying to hold formation and be aligned to enemy’s future position with weapons and defences covering angles from which attack will come. If this is the tactics of both sides, it won’t be much fun.

I think more common will be guarding and patrolling planets, moons and some asteroids on some high orbit, and the other side approaching, again on well known orbit. The defenders will wait, leaving “mine fields” of sleeping missiles. Attacker will have probably advantage in numbers and total destructive power, otherwise there is no chance to succeed.

I think the only purpose of spaceships will be to show power, control space and serve as deterrent force. Same as current fleets of aircraft carriers with planes loaded with nuclear weapons, capable of destroying anything. So no wars between nations (or organizations, or whatever) having in service big spaceships.

thanks myn.pheos, i appreciate that ur really putting a lot of effort into the physics as well. my only concern was that design would take a back seat, but i can see it hasnt.:slight_smile:

i like the idea of it patroling planets/spacestations. i know i wouldn’t take any of my ships up against it in a test of brute strength. no in order to beat something like this ud need a well formulated plan.

also im diggin the sail/foil things. neat idea. kind of like a sailing ship look to it.

keep up the good work and cant wait to see u start modelling

i know i wouldn’t take any of my ships up against it in a test of brute strength

it would be cool to form a huge blender ship fleet!

Well, yes, but there are dozens of threads on this forum for artists to show their artistic works. Would you begrudge us few engineers-who-are-also-artists our one pathetic thread?:frowning:

I manage to straddle the line between artistic and scientific. I find that doing some math to figure some parameters is more of a springboard for my art, not a hindrance.

That is what I meant. No tutorial can teach one how to imagine things, but one on how to use Blender to figure a spacecraft’s volume, heat radiator placement, etc. would be quite useful.

70 meter diameter (35 meter radius) at 2/3 g will spin at about 4 to 5 RPM. This is a bit high for civilians but a trained military crew should be able to acclimate to this with little problem.

It might be fun. It will make interplanetary combat more like a game of chess or Go, instead of like a fist fight. You try to use broad strategic maneuvers to fool the enemy into committing their forces to a decoy objective, then surprise them by hitting the real objective.

There are some notes here:
http://www.projectrho.com/rocket/rocket3z.html
under “advanced tactics”

nyrath: i really am interested now in this approach to designing a space ship, and i know that a tut from either of u would be good. maybe on my next ship i design u 2 will swing by my thread and make sure my reality is up to snuff, cause i really dislike math.

find that doing some math to figure some parameters is more of a springboard for my art, not a hindrance.
Exactly!

I was thinking a bit about the heat and energy inside the ship and found out that there will be quite hot inside. If energy needed to operate the reactor and engines is 60 GJ per second, and few GW is powering other things there, all with not perfect efficiency, about 100 GW must be radiated away. I have there 4000 tons of coolant, plus some structural weight can be used for low temperature transfer. High-end material technology have to take care of this. I think the artificially produced diamonds will be quite common in future heat exchangers. The cooling and power system has to radiate less energy in combat while shooting, as the heat will be converted into electricity to power the guns and efficient lasers, as well as maneuver engines.

But I think I stop worrying about that, or I’ll never get to the funnier modelling part.

It might be fun. It will make interplanetary combat more like a game of chess or Go, instead of like a fist fight. You try to use broad strategic maneuvers to fool the enemy into committing their forces to a decoy objective, then surprise them by hitting the real objective.

The funny part is for ship commanders, while the generals and planners at HQ spoiled by today’s real-time overview of battlefield will have to wait few minutes to get information. The strategic operations will be really important in case of war ever starting.

I want the ship to be armed with two kinetic guns with 15 GJ energy per shot, one laser (or particle gun) of 20 GJ beams and 16 missiles with several 10 Mt nuclear warheads. And of course, some defensive lasers and guns.

my head has officially explodified! thats some complex stuff…

That is some complex stuff that will probably roast it’s crew and spaceships in proximity…

Just imagine this ship docking at station. The power generated by it’s engines is so big, that pointing them towards the station would overheat it in few second, burning it’s inhabitants. So certain approach patterns are only available (but this is normal, in space everything circles on orbits). But there is other risk: while the trust power is 300 GW, there is 50 GW emitted perpendicular to this to each side from 100 000 sq m radiator. The temperature of this huge sail is 2000 K and power output 1 MW/sq m. Quite a big problem for the station. Either the ship will just orbit few hundreds to thousands meters away, or will need to be equipped with massive shields and equally massive radiators (reflecting the heat isn’t an option, as this would overheat the docking ship). Departure is the same problem as arrival, I think no small tugboats can exist (they would need the same thrust, thus the same power and same total radiator area).

I have an idea that there will be cables stretched between ships and stations with cablecars travelling attached to them. This seems to be reasonable solution.

or, to dock at a station…have the ship turn its engines off and pull the ship into the station via tractor beam or magnets? (im not to sure about the magnet one, but its all i can think of right now)

or, to dock at a station…have the ship turn its engines off and pull the ship into the station via tractor beam or magnets? (im not to sure about the magnet one, but its all i can think of right now)

Magnets have to be quite huge and strong to attract 70 000 tons of mass (and not everything in the ship is metallic). It would also require more things to be carried, because there would be electricity produced by movement in magnetic field (the same as EMP). Although I don’t know if the amount of electrical power would be significant (the ship has to be shielded in any case), the station would have to be equipped with insanely huge electromagnet.

If any tractor beams existed (the most common sufficiently strong attractive forces are gravity and between opposite electrical charges and of course magnetic), there would be a one huge problem. If you want to push an object to one, both move towards. There isn’t any friction in space, so also the station would accelerate towards the ship (although slowly than ship towards the station, because the stations are usually bigger than ships). And accelerating station doesn’t stay in its orbit, so it needs engines to stay in the same orbit. Therefore, the same amount of thrust is needed for the station to stay in orbit (this is basically to move the engines and fuel supply to the station). The things might return to previous state when the ship leaves at the same spot as it has arrived, but for geostationary stations any change in orbital parameters isn’t desired. I don’t know almost nothing about orbital mechanics, so take this with reserve.

It might be fun. It will make interplanetary combat more like a game of chess or Go, instead of like a fist fight. You try to use broad strategic maneuvers to fool the enemy into committing their forces to a decoy objective, then surprise them by hitting the real objective.

Taking into account that you cannot simply fly straight lines in space, you cannot start when you want and long times to reach your destination there will probably be a large group of planners equipped with powerful computers playing their interplanetary chess.