Spaceship Design

[Mikos]

Hello,
I want to design sci-fi spaceship based on (at least partially) realistic concepts. It should be centered around Polywell fusion reactor, can you please tell me what do you think about my design and give me some tips? I want to discuss every aspect of ship.

Some basic info - ship should have crew of few dozens people (but it should be controllable by only few people if necessary). It should be able to land on and to launch from a planet (so it is single-stage-to-orbit vehicle and it must have some aerodynamic properties and good structural integrity). It should have life support system with _perfect_ oxygen and water regeneration (so if something goes wrong, food is the only limiting factor for crew, not oxygen or water).

First there is energy system. There should be battery of radioisotope thermoelectric generators (RTG) as a small uninterruptable emergency power supply. Then there should be battery of powerful hydrogen-oxygen fuel cells and water electrolyzers. Fuel cells should have enough power to charge a superconducting magnetic energy storage (SMES) battery and start main Polywell fusion reactor (and also to keep basic ship systems alive in case of main reactor failure). Electrolyzers are there for regeneration of oxygen and hydrogen from water when main reactor is working. About main Polywell fusion reactor - it should give at least 10 GW (20 GW would be better) of power, fuel should be hydrogen and boron B11, direct energy conversion should be used.

Next is defence. There should be powerful 1 GW free electron laser (FEL) tunable in range of frequencies from short wave IR, through visible spectrum, to UV. There should also be a magnetic plasma shield (artificial magnetosphere) for shielding crew from solar flares, galactic cosmic rays and other forms of particle radiation.

Last thing is propulsion. I will go on thin ice and give the ship speculative gravitomagnetic drive. It should be based on gravitomagnetic London moment (as measured by ESA scientists - Tajmar et al. - near rotating superconducting ring) and according to Heim-Dröscher theory, it should also allow FTL travel. Don't get me wrong, I don't believe that Heim theory is right, but it is the only theory which gives us possibility for FTL travel right now (and gravitomagnetic London moment measured by Tajmar et al., which is real effect, can be explained by it), so it is good option for my sci-fi spaceship

One problem I can see is cooling. There will be _huge_ amount of waste heat from Polywell fusion reactor, FEL laser, etc. And this is problem in space, you can only use radiative cooling and I think radiators for at least 500 MW of waste heat will be quite huge. Also remember that the ship should be able to launch from and land on planet (so some aerodynamic profile must be preserved). One possibility is open-cycle cooling, but I don't want to have enormous amount of fuel on ship just for cooling. Or would be the amount of waste helium produced by 10 or 20 GW Polywell fusion reactor enough for open-cycle cooling? I am afraid it wouldn't...

[drmike]

I don't quite understand why you need so much power if the fusion reactor is not the primary rocket engine. Reduce your power by a factor of 10 to 2 GW (still plenty to punch holes in things with an FEL). Then you can add cooling fins that fold out when outside an atmosphere and use the atmosphere to help with cooling otherwise. It is just fiction

Sounds like a great sci-fi story so far. Good luck with it!

[Mikos]

I don't quite understand why you need so much power if the fusion reactor is not the primary rocket engine.

Fusion reactor is not the rocket engine, but it is power source for gravitomagnetic drive.

If I look on Space Shuttle, the overall power of rocket engines at takeoff is about 12 GW and mass of Space Shuttle is about 2 000 metric tons. My spaceship should weigh about 100 000 metric tons. So I don't think that 10 - 20 GW fusion reactor is too much.

Also I have read some papers about Heim-Dröscher theory, but I don't know how much energy consuming would be FTL propulsion based on it (I didn't do the math, it seems to be complicated). But I am afraid it will be quite energy intensive application.

Sounds like a great sci-fi story so far. Good luck with it!

Thanks! I want this ship to be really well-thoughtout, this is why I am writing here If you have some other tips, I would be really pleased to hear it.

[Mikos]

Btw. is there somebody who knows something about shaped nuclear charges (also known as Casaba-Howitzer)? It looks like militarized version of project Orion (nuclear pulse propulsion) shaped charges.

It would be apparently great space weapon (much more effective than nuclear-pumped X-ray laser), so I am considering it for my sci-fi story. From what I have found, resulting plasma jet from Casaba-Howitzer shaped nuclear charge should have really low divergence and can carry up to 10% energy from explosion. But informations about it are unfortunately scarce, it is still classified (only some general informations have been declassified with project Orion).

[dweigert]

Actually, your ship would be better off being a a "carrier" that doesn't enter the atmosphere. That's what cargo shuttles are for. This way you can make the crew quarters the most efficient shape, and have lots of radiative surfaces to dissipate your waste heat. You can also have cargo cannisters clamped to the outside of the ship for items that don't require shielding.

[Roger]

Actually, your ship would be better off being a a "carrier" that doesn't enter the atmosphere. That's what cargo shuttles are for.

So true.

I think someone like David Weber has this covered really well. Weber is noted for basing his stuff on really good science and engineering. Webers ships are powered by "fusion bottles" too, funny thing about that.

[drmike]

That certainly explains the power level! If it will be that big, I agree with the others that keeping it in orbit and using smaller transports for planet bount makes more sense than dropping that much mass into a gravity well.

For shapped charges you'd need either a radiation source for compressing D-T or the use of Pu with a neutron source on one end and good neutron reflectors around it. It's an interesting problem which is supposedly being worked on these days. Since you have FEL, throwing out a shaped charge and then detonating it with the FEL light seems like a reasonable tactic - it'd be hard to detect the real warheads from dummies until it was way too late. And since you are fusion based, going with a D-T compression weapon fits the story line better than shaped Pu.

Seems to me you have a very good idea of what you want to do, so it should be good!

[Zixinus]

About main Polywell fusion reactor - it should give at least 10 GW (20 GW would be better) of power, fuel should be hydrogen and boron B11, direct energy conversion should be used.

An idea I like to play about is to have a couple of kilograms of He-3 and Deuterium mixture. For "turbo" mode. If you want to be cheesy a little, or when you just need that extra power in battle. From what I understand, it is a more powerful reaction. Or was that Li6-D or Li6-Li6?

Next is defence. There should be powerful 1 GW free electron laser (FEL) tunable in range of frequencies from short wave IR, through visible spectrum, to UV. There should also be a magnetic plasma shield (artificial magnetosphere) for shielding crew from solar flares, galactic cosmic rays and other forms of particle radiation.

Don't forget point defence lasers and/or defence rockets!

Actually, your ship would be better off being a a "carrier" that doesn't enter the atmosphere. That's what cargo shuttles are for. This way you can make the crew quarters the most efficient shape, and have lots of radiative surfaces to dissipate your waste heat. You can also have cargo cannisters clamped to the outside of the ship for items that don't require shielding.

That, and a Shuttle/X-33/something type jet-engine something might look much slicker to carry your heroes about. And less of a target.

EDIT: Oh, and I always recommend this site: http://www.projectrho.com/rocket/index.html

[Roger]

Don't forget point defence lasers and/or defence rockets!

Layered defense.
-Point defense lasers
-short range anti missile missile
-long range range anti missile missile

-Recon missile
semi autonomous modified long range range anti missile missile using passive search, and a whisker laser com back to the mother ship. Useful for laying "doggo" for long periods of time & acting as a solar system perimeter alarm beacon.

[Mikos]

Thanks for all tips!

About spaceship being only a carrier that doesn't enter the atmosphere - I know it is much more simple engineering solution, but I want for my sci-fi story ship that would be able to land on a planet. Propulsion shouldn't be a problem (thanks to my fictional gravitomagnetic drive), so the only big problem I can see is radiative cooling - designing radiators to be able to radiate enough heat in space and ship to be still able to enter atmosphere.

Any other tips? I have read in the past that theoretically there can be radiative cooling based on gas dynamic laser principle, but I can't find anything about it now. Do you know anything about it? Some thoughts?

Don't forget point defence lasers and/or defence rockets!

Well, it should't be war ship. The big FEL laser is there for defence "just in case" (and for destroying small objects in the path of ship).

Btw. you think that missiles are good option in space? I don't think so. They would be slow and can be easily destroyed by defence laser.

[Mikos]

I have another question - how much (in terms of weight) hydrogen and boron will be consumed (approximately) by 10 GW Polywell reactor? And how much helium will be produced?

Btw. can you tell me how efficient (even if it is only guess) will be such reactor with direct energy conversion (and therefore how much waste heat will be probably produced)?

[Zixinus]

Any other tips? I have read in the past that theoretically there can be radiative cooling based on gas dynamic laser principle, but I can't find anything about it now. Do you know anything about it? Some thoughts?

In essence, it most likely would violate thermodynamics.
Discussion here:

http://groups.google.com/group/rec.arts ... 710bfee99f

and here:

http://groups.google.com/group/rec.arts ... 67351631d1

Again, take a look at Atomic Rocket. It has many hints in this regard.

Btw. you think that missiles are good option in space? I don't think so. They would be slow and can be easily destroyed by defence laser.

That depends on what againts and what we assume, no? You can protect missiles againts laser fire and their speed would be more then adequate, especially considering the increased level of accuracy and persistence. Also, you may be limited how many times you can fire a laser, while you can fire much more missiles then it can take care of in a flash. If a laser misses, then the target is not hit. If a missile misses, then it can correct its course and still hit. With enough fuel, the missile can track its target throughout the solar system.

Btw. can you tell me how efficient (even if it is only guess) will be such reactor with direct energy conversion (and therefore how much waste heat will be probably produced)?

That would depend very much on what is the design of the reactor, now wouldn't it? At maximum, about 95% efficiency can be archived with a direct conversion Polywell, the rest is heat. That is not counting the energy you need to spend on keeping the Polywell itself, which is at least somewhere about 50%, maybe less.

[Mikos]

In essence, it most likely would violate thermodynamics.

Thanks for these links. I have read something else (but of course it could have been wrong). I _think_ (but I am not sure, it was long time ago) it was NASA scientific paper and it showed that there would be no thermodynamics violation in that particular gas dynamic laser cooling concept. But I don't remember any details and can't find anything about it So I am not sure...

Again, take a look at Atomic Rocket. It has many hints in this regard.

Yes, I know Atomic Rocket. It is great source of information for writing realistic sci-fi stories.

That depends on what againts and what we assume, no? You can protect missiles againts laser fire and their speed would be more then adequate

How can you protect missiles against laser fire? If you have powerful enough laser, then nothing can protect missiles from it (at least I think). And even if you have super powerful nuclear warheads, you must get them really close to target to destroy it (because in vacuum the only destructive result of nuclear explosion would be intensive X-ray flash and thanks to inverse square law, it wouldn't have too distant destructive range).

This is why I have thought about shaped nuclear charges (Casaba-Howitzer) - resulting highly directional plasma jet would have much more devastating effect (and I hope also longer range).

Also, you may be limited how many times you can fire a laser, while you can fire much more missiles then it can take care of in a flash.

Well, 10 GW Polywell fusion reactor should give you more than enough power for really powerful (and highly efficient) FEL laser. The only thing which can limit how many times you can fire would be waste heat. But if you are able to get rid of waste heat from 10 GW fusion reactor, waste heat from 1 GW FEL laser wouldn't be a problem.

[Zixinus]

Thanks for these links. I have read something else (but of course it could have been wrong). I _think_ (but I am not sure, it was long time ago) it was NASA scientific paper and it showed that there would be no thermodynamics violation in that particular gas dynamic laser cooling concept. But I don't remember any details and can't find anything about it Sad So I am not sure...

Somehow that doesn't make sense to make. Personally, it sounds like technobabble, or at least something that might not work effectively in the vacuum of space. I know they can use laser cooling to make Borns-Einstein Condensatum (spelling?) but that is done by getting rid of the "hottest" molecules (so that cool heads would prevail ). Essentially, active cooling done on a atomic scale. The atoms are held by lasers.

Furthermore, I've once found a paper discussing a perpetual-motion-powered craft on NASA's site. Might have been just a library item though.

How can you protect missiles against laser fire? If you have powerful enough laser, then nothing can protect missiles from it (at least I think).

Armouring the warhead? Giving it a surface on which heat may dissipate quickly? The warhead may even make random burns to make it harder to hit?

And then there is good old sheer quantity.

Again, however, this argument goes on about what you assume. The key is sensor precision and refire rate.

And even if you have super powerful nuclear warheads, you must get them really close to target to destroy it

Actually there might be a way: once the missile is sufficiently close enough, you can eject the warhead from the rocket, making it harder to detect. With a extra engineering, you can even make the warhead go with some extra speed for it to boot.

But if you are able to get rid of waste heat from 10 GW fusion reactor, waste heat from 1 GW FEL laser wouldn't be a problem.

The question is, how fast? Does it take a minute or a second? Having the waste heat of a 1 GW FEL laser might take more time then a less powerful laser.


Also, I'd reccomend this site for study: http://panoptesv.com/SciFi/DeathRay.html

Sadly, it is much incomplete, but it still offers valuable information.

[dch24]

Borns-Einstein Condensatum (spelling?)

Bose-Einstein Condensate