Semi-OT: A General Tech Question Thread for me :)

[El_Phil]

Given the choice between floating into scalding hot coffee when the ship stops accelerating or a rotating section I know what I'd choose... Full on artificial gravity.

If you don't like rotating sections then perhaps consider the rotating ship. An idea I got from a Heinlein book, essentially the enire ship 'rolls' along. No friction or bearings to think about, full gravity for the whole ship (admitedly variable strength, but you can't have everything) it seems clever. I haven't put that much thought into practical issues, but none are jumping up at me right now.

[Wolfman77]

Wouldn't a rotating ship require alot more thrust to accelerate. Manuverability would also be greatly reduced, I believe, as it would be harder to change directions. Another problem turning when spinning is that the thrusters to move you into a turn would be rotating and would create a couple of problems, depending on how much you wanted to explain.

They would need to be pulsed on ond off in a serial order to keep thrust on just one side of the ship.

If you wanted to go farther into it, then that wouldn't work either as each thruster would still fire in an arc, not just at one point. It would be massively unstable.

I can't think of any way to explain around this, and there may be other problems I haven't thought ofas well.

[Starhawk]

Yeah like firing weapons lol think about it if your ship is rotating a cannon that was locked onto the enemy a second ago won't be after the ship rotates.

Also grav "plating" works for me for now as just looking at an Icaran ship it's clear there's no room for a rotating section in the design (see attached).

As far as constant acceleration goes I agree with you there it would suck to float into something if the ship comes to a sudden stop lol

[El_Phil]

Wolfman77 said:
Wouldn't a rotating ship require alot more thrust to accelerate. Manuverability would also be greatly reduced, I believe, as it would be harder to change directions. Another problem turning when spinning is that the thrusters to move you into a turn would be rotating and would create a couple of problems, depending on how much you wanted to explain.

They would need to be pulsed on ond off in a serial order to keep thrust on just one side of the ship.

If you wanted to go farther into it, then that wouldn't work either as each thruster would still fire in an arc, not just at one point. It would be massively unstable.

I can't think of any way to explain around this, and there may be other problems I haven't thought ofas well.

How to solve that? Computer controled constant correction. Modern aircraft (F-22, Eurofighter) are 'dynamically unstable' airframes. You kill the computers and the plane goes out of control. Similar thing with this. Or just pre compensated burns, you allow for the fact the thruster is moving when you calculate the burns. You know all the factors that will affect the stability so it's calcuable, with fast enough computers.

Weapons however are tricky, it would depend on how fast the outer edge of the ship is spinning, which would depend on how much gravity you want in the ship and how big the ship is.

OR the ship rotates round its axis of movement. The main engines are mounted on the 'hub' of the ship as are your forward firing main weapons. Simplifies some of the problems certainly, if not solving all of them.

[Wolfman77]

Yup, computers could do the trick there. And with some sort of Thrust vectoring you could control it's tendancy to pitch throughout each burn. It would still have poor manuverability though.

Nice ship, btw. I guess these problems won't matter for you ship much but they are still fun to discuss. Grav plating sound ok to me, but then I'm ok with just about anything in sci-fi. At least there are not any commonly accepted theories that prohibit it from functioning (well none that I'm aware of anyway).

[kerensky]

As far as shooting while spinning, I don't knw if this came from a book or video game, but the ships spun to keep gravity but when they went into combat or needed to do some tricky maneuvering, they killed the spin and everyone strapped in or floated.

[El_Phil]

That would work as well, the problem would be the inertia. Just because you stopped powering the spin doesn't mean it will suddenly stop, there's no resistance (or practically none) in space so you have to apply power to stop the spin. Not a big problem granted, you got it spinning in the first place after all.

Gravity plating. Wonderfull and how do you propose for this to work? Last I checked you needed mass for gravity.

Lets see how you would get this. OK use Newtonian gravitational theory, its fine for practical stuff involving small fields. And its a hell of alot simpler.

So to get earth strength gravity you need about 6E24 kilograms, or the mass of the earth, at a distance of ~ 6400 km. This isn't really practical to lug around, but your plating is on the floor! Say under a few cm of carpet (or funky futuristic space floorboards) lets say its 1 cm down. So you only need 9E15 kgs of mass to create that much gravity. Tricky. Oh and it's unidirectional so your crew on the deck below are being attracted to the ceiling.

Frankly I can't see how you can ever get that into plating and then directional. But I'd like to hear this theory that would be fine.

[Wolfman77]

I never said I could explain it. Only that "there are not any commonly accepted theories that prohibit it from functioning (well none that I'm aware of anyway)."

Currently, it is generally accepted that gravity is mediated by a particle called a graviton. I admit, there is no solid proof of its existence, but then science has relatively few proofs when compared to theories. If we assume the graviton does exist, then it is not that much of a stretch to think that with 2000 years more science, that someone might figure out how to control it without needing all that mass.

If you have proof that the graviton does not exist, then please share this information with the rest of the scientific community so they can spend their time on other theories.

If you do not believe that science will ever explain anything not already known, or pose new questions never thought of, then you will always nit-pick science fiction, and never gain anything from it.

Just as a note: Newtonian gravity works OK on large scale, but breaks down at smaller scales. It does work for your example, however, because with newtonian gravity that is considered large scale. Small scale is considered less than the width of an atom. But then, I'm just being nit-picky.

[Hunpecked]

What strikes me most about this thread, with its frequent emphasis on what's "really" possible, is that once you assume "warp" space travel (i.e. as in the SE IV game), 21st Century science goes out the window. Perhaps it would be more productive* to speculate how the "warp" travel already built into the game can explain other game features. Example: For in-system travel, why not replace Newtonian acceleration/deceleration, with its inconvenient mass/energy/velocity/fuel limitations, by a continuous "micro-warp" drive with constant velocity (very convenient) and whatever limitations you like? BTW, this is somewhat similar to the "stutterwarp" in the Traveller role-playing game, which is based on, yes, REAL science, i.e. [begin handwaving] quantum tunneling [end handwaving].

Or take the "Alderson Drive" in the Niven/Pournelle novel "The Mote in God's Eye". The "warp points" in this fictional universe arise from an as-yet-undiscovered "fifth force". Presumably the discovery of this new force would lead to a whole new branch of physics and many practical applications, but to my knowledge the authors made no use of this technology beyond interstellar travel. If so, then I'd say they missed a good opportunity.

Back to SE IV. You want "shields"? No problem! Apply the same game technology used for interstellar travel to generate a "warp field" around your ship that "warps" incoming matter/energy harmlessly AROUND the vessel! Now for game/story purposes you may want limits on how much "incoming" can be deflected (leaky shields) or you may want "incoming" to "use up" shield/warp energy (consumable shields). Your weapons can be modified shield projectors that create a long thin warp field (as opposed to a short fat shield) along which you can fling projectiles, photons, anti-protons, etc. toward enemy vessels. Since warp fields defy "conventional" physics your "beams" don't scatter and efficiency is so amazingly high that minimal cooling is required.

Just as the first lasers led to multiple practical applications in telecom, weaponry, medicine, computers, chemistry, physics, etc. I would expect a fictional scientific breakthrough to affect many aspects of a scifi story.


*by the phrase "be more productive" I mean "waste time more efficiently"

[Baron Munchausen]

In order for humans not to be disoriented (dizzy) from the rotation, a rotating structure must have a cycle time (complete rotation) at at least one minute. In order to get 1 g of acceleration in a 1 minute rotation time you need: 33 feet per second * 60 seconds = a wheel 1980 feet in circumference. (approximately 650 feet across) Since any 'upper' decks within that radius will have correspondingly less g, they'll have to be 'storage and utility space' and only decks that far out or farther will be regularly inhabited. So you'll need pretty large ships for a 'routine' 1 g environment. I suspect that colonies will eventually be built that have this level of gravity but I doubt that many moving ships will.

The balance factor is another sticky problem but I suppose it's more solveable than the sheer size requirements. In order to rotate effectively the ship/structure will have to be relatively balanced, but of course it will never be perfectly balanced. Various controls can be used, including thrusters and internal movement of material, like stored water or other fluids. Even with computer controlled pumps moving fluids around you can't have a response time or a margin of error that can handle humans running around doing their daily business. Another reason that rotating ships will probably be impractical but colonies will be important enough to deal with the problems.