A Drive for Drives

[chuck_starchaser]

Been doing a bit of googling around for inspiration to drive my small cargo ship drive.
So here's some stuff I've put together. I think it would be a good idea to build a bit
of a library of drives (engines) to be shared among modellers. I want my drives to look
at least somewhat realistic in the sense of being inspired in existing thrusters or
flights of fancy from the technical people's side, rather than flights of fancy a bit
too fanciful, but also more detailed than the typical pipe and funnel.

Got images from too many sources to keep track of, including NASA/JPL, but one site
that has a wealth of info on future drive technologies I found is
http://www.daviddarling.info/encycloped ... types.html

The basic scoop is, the drive with drives is towards higher exhaust velocities. Ion
engines are a vast improvement over chemical rockets, and then there's a whole array
of plasma engines, culminating with VASIMR perhaps, but the other day the ESA and these
Australian students came up with a 4-grid ion engine that beat the crap out of VASIMR.
Then there's plasma fusion plans. Anyways, I'll try to add to this thread gradually.

Here's an early ion engine experiment at NASA back in 1959:



Here's the ion engine that flew the amazing NASA Deep Space 1 craft:



The ESA recently sent its own ion-drive propelled craft to the moon; Smart 1:



The Russians came up with the VASIMR idea, and the Americans perfected it, as usual.
Here's some VASIMR diagrams from various sources:



VASIMR prototypes and tests:



And VASIMR-powered concept crafts. Overly simplistic, I'd like to point out.
Notice in the top VASIMR schematic it shows tubes injecting pumped hydrogen onto the nozzle;
and if you look at the nozzle in the prototype pic you'll see holes on the sides,
so make sure to put a bunch of pipes going into the sides of the funnel. Etceteras.



But like I said, the other day, a bunch of Australian students working under contract
for the ESA (European Space Agency) managed to build a prototype of a new "4-grid" ion
drive in 4 months that beat the crap out of the projected exhaust velocity of VASIMR...



Would be nice, specially with the upcoming Ogre integration and shader power, to give
different types of drives different exhaust plumes. For real life examples:

Hall effect ion drive exhaust:



Deep Space 1's ion drive exhaust:



VASIMR exhaust:



Most of the advantage of ion and plasma drives is that, having high exhaust velocities,
they need use less propellant for the same impulse. This assumes that the energy to
propel those ions is cheap. And with a nuclear power plant on-board, it is.
Ironically, no nuclear powered ion engine craft have flown yet.
Anyhow, for us modellers, the catch is not to forget to have a power plant to go with the drive.
Here's Cassini's nuclear power plant; --actually 3 power plants--; and please
don't miss the detail in the top right diagram, which, unlike the others, shows the
radiation shields on top of the power plants. Essential...
BTW, Cassini's nuclear plant is to power the instruments, not for propulsion.



But of course, there are drives in the drawing boards that would use fusion power
directly, rather than make electricity and then use electricity to power the drive.
One such research project is start a controlled fusion reaction in an electrostatically
confined plasma in a tube. Check out this company working on it under a NASA contract:
http://www.n-plasma.com/fusion.html

The other detail not to miss is radiators. No drives or power plants will ever be
100% efficient, and getting rid of heat in space is problematic. Cooling rads should
probably dwarf many of the other greebles.

Anyways, I'll see what I can come up, models-wise, but others feel free to contribute.
Anyone texturing, though, see if you can come up with real materials.
Tungsten is preferred as a heat conductor, but doesn't have a fraction of the emissivity
of graphite; so rads could have a tungsten finish except for the outer surfaces
looking matte black, for instance, --i.e. graphite-coated.

[Ryder P. Moses]

Vectored thrust on a jet engine. Saves you a lot of hassle with turning jets and such.

[chuck_starchaser]

Yeah, I'm not sure how much vectoring there may or may not be in future drives.
Possibly by introducing asymetric voltages in the grids of ion engines, but still wouldn't vector much.
Problem is, with jet engines, and chemical rockets, even ion engines, the force or the
particles (their "temperature") can be handled or deflected by conceivable materials,
but once you get to plasmas, and fusing plasmas, and temperatures of 5 million kelvins,
who's going to deflect that beam?

I think it would be more reasonable to have weights you can shift around, then you fire the engine,
and the mass asymetry causes your ship to turn.

That's something my cargo ship will have, by the way.

Anyways, for space flight you can do with one main engine and a bunch of little attitude jets,
as long you you don't need to dogfight, of course; but dogfighting in space has always seemed a bit
weird a concept to me.
For my mod, I'm thinking there will be some fighting, but not "dogfights" per se, more like a missile commander kind of thing.

[Bodo]

I suppose you will use an FFE kind of flight modell (accelerate as long as possible - turn - decelerate). problem is, this kind of engines still have huge fuel consumptions. you'll need most of your cargo room for fuel.

As for vector thrust, I think manouvering jets are more practical, since they're more versatile anyways. better compare it to Naval vessels than airplanes: yes, bigger ships do have vector thrust, but it isn't of much use when trying to dock on a mole. they still rely on waterjets for that purpose. And since in space you cannot use fraction to achive a change of course as it is the case for boats and airplanes, the whole thing gets kind of superfluous. The only interest of a combat spacecraft would be to get it's nose pointing a certain direction and pick up speed in that direction as fast as possible, which I think can be achieved way faster with some powerfull manouvering jets (and way more precise).

[Zeog]

... but once you get to plasmas, and fusing plasmas, and temperatures of 5 million kelvins,
who's going to deflect that beam?

Plasmas are charged particles by definition. Deflecting charged particles is really easy (depends on their speed though) with em-fields.

[chuck_starchaser]

Well, technically plasmas are electically neutral macroscopically (positive ions and electrons balance out), but what I'm saying is that if we're trying to maximize exhaust velocity and minimize particle mass, it means that the energy per particle is going through the roof, and there's no magnetic or electrostatic field of any strength practically achievable that will vector the beam by any considerable angle. But like Bodo said, if all you care for is to turn your ship around you can do so with chemical maneuvering jets, or like I proposed, by shifting some internal weight in the ship, and using forward thrust with a controlled asymmetry in your moment of inertia. Much simpler than trying to vector the engine exhaust.

[zaydana]

i think tho, if we can build a much bigger ion thruster, wel'l probably also get the tech to build a much larger coil Think some massive superconducting electromagnet, i'm sure we could vector the thrust with that, and if electricity is no problem (nuclear reactors...), then vectoring thrust won't be a problem either. Remember... this is the future we are talking about.

[chuck_starchaser]

I'm rather skeptical about "the future". Back in the 50's and 60's there was a reason to feel so enthusiastic about the progress of science and technology.
Anyhow, I won't say it's *impossible* to vector the thrust, but I do say it isn't worth it. Check Bodo's post again; I couldn't have said it better. Basically, you don't need it.

[zaydana]

yeah, i'd agree too Its definitely not worth it. Apart from possibly in dogfighting, if it happens, and if you can vector it enough to be worth more than maneuvering jets, which i highly doubt would happen. Anyhow, point is, its possible Not useful.