Post Your Favorite Sci-Fi Concept Art

Just what it sounds like.

Re: Post Your Favorite Sci-Fi Concept Art

Postby Triggerhappy » Tue May 16, 2017 8:49 am

Are you considering that your sphere station will need engines, fuel tanks, reactors and laser turrets?

Good point on the laser power consumption but kilojuels powering a laser is a lot more than what would be needed to slide rails against one another

Much less maintenance than laser turrets and reactors, yes
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Re: Post Your Favorite Sci-Fi Concept Art

Postby Dinosawer » Tue May 16, 2017 8:52 am

The power needed to move your station (with fuel) is the same as the power needed to move your station (with rails).
Newton, conservation of energy, and all that.
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Re: Post Your Favorite Sci-Fi Concept Art

Postby Triggerhappy » Tue May 16, 2017 8:53 am

But you don't loose mass.
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Re: Post Your Favorite Sci-Fi Concept Art

Postby Cornflakes_91 » Tue May 16, 2017 8:54 am

Triggerhappy wrote:Are you considering that your sphere station will need engines, fuel tanks, reactors and laser turrets?


No, one dinky solar panel feeding a cap, like your thing.
Also, a second time, no engines :P

Triggerhappy wrote:Good point on the laser power consumption but kilojuels powering a laser is a lot more than what would be needed to slide rails against one another.


Nope, wrong actually :P

E=(mv^2)/2

Do your calc to accelerate a thousand tons of rock to any noticeable speed.

The laser needs lots less energy to divert a rock half a degree :P

Triggerhappy wrote:Much less maintenance than laser turrets and reactors, yes


Your giant rapid heavy load movement system needs less maintainance than turning a few tons of laser emitter? Howso :P

Nobody said reactors, feed a capacitor and pull from that the odd time you actually have to divert a rock.
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Re: Post Your Favorite Sci-Fi Concept Art

Postby Triggerhappy » Tue May 16, 2017 9:03 am

Ill get back to you all with a 3 rail station

This laser will need to vaporise the whole asteroid unless it's actually powerful enough to move said multi-kilogram-probably asteroid in a short time? And that takes less power than shifting a station in on itself?

Comment - this was meant as a short response system, where the asteroid is detected only seconds out .

This can be cheated too - when slowing the rail movement after an evasion that energy can be converted back into electricity, saving some ( a lot? ) Of power.

Laser emitters need repairs and replacements, often after only a few shots. A rail system can be built to be far more durable over long uses.
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Re: Post Your Favorite Sci-Fi Concept Art

Postby Cornflakes_91 » Tue May 16, 2017 9:44 am

Triggerhappy wrote:Ill get back to you all with a 3 rail station

This laser will need to vaporise the whole asteroid unless it's actually powerful enough to move said multi-kilogram-probably asteroid in a short time? And that takes less power than shifting a station in on itself?


Vaporise? Who said vaporise?
Vaporise a few kg of mass on the surface of the rock and give it an "engine" to push it off the collision course.

Triggerhappy wrote:Comment - this was meant as a short response system, where the asteroid is detected only seconds out .


So... lets assume your weird station.
100 meter arm length ~ 5 meter edge length. Filled with granite. Massing about 14000tons total (13.75e6kg).
You have 10 seconds to move the whole station about fifty meters, because thats the maximum you can shift the cross point without moving the center of mass of the whole construct (less if the crosspoint isnt massless which it cant be because you have the mechanics to throw around 14kilotons around in a few seconds there)
netting a needed top speed of 5m/s.

Which equals 171e6 J.
171MegaJoule.
Or about 40kg of TNT to get out of the way in time.


(with the time you need to accelerate included you need a higher top speed, 10m/s (at 1/5th of a g) quadrupling the energy needed=160kg of TNT)

Plus losses and the center piece i neglected for simplicity.
So you are easily up to 60(240) kilogram of tnt you waste with every avoidance maneuver.

And those costs also go up with the square of the inverse of the time you take to avoid

You are better off just throwing the energy at the rock.
In either laser form (less efficient, but less maintainance) or in form of a hundred gram block of said granite in a mass driver.

Triggerhappy wrote:Laser emitters need repairs and replacements, often after only a few shots. A rail system can be built to be far more durable over long uses.


[citation needed]

My laser pointers last for decades.
Lab lasers also cant be used only once or twice, not even the many kilowatt ones.
As long as you cool them appropriately a laser has basically infinite lifetime.

I also personally have access to dirt cheap 40W continuous mode semiconductor laser modules now which have basically unlimited lifetime.
which can be pulsed to a kilowatt or so with enough cool off between usages.

And theres 10kw industrial cutting lasers to buy now.
(continuous mode with potential pulsing to much higher levels again.)
And those things definitely last longer than one or two uses :P
Extrapolate to a world where space is industrialised and you have an industrial need for a couple hundred kilowatt lasers.
Affordable industrial reliability level laser systems
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Re: Post Your Favorite Sci-Fi Concept Art

Postby Triggerhappy » Tue May 16, 2017 10:34 am

There is sill the advantage that you are not ejecting mass.

Cost wise, I would still guess that a mechanical rail system constantly less than several laser emitters powerful enough to vaporize ANY amount of rock.

Maintenance wise, you need to keep several emitters fully functional, unmolten, undamaged. That's power lines and targeting systems for each one. And at that point you have an equivalent of an industrial battle platform.

Forwarding all this to the man who's idea this was. Will tell response when I get it.
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Re: Post Your Favorite Sci-Fi Concept Art

Postby Cornflakes_91 » Tue May 16, 2017 10:44 am

Triggerhappy wrote:Cost wise, I would still guess that a mechanical rail system constantly less than several laser emitters powerful enough to vaporize ANY amount of rock.


a 150 megawatt continous power rail system plus all the structural features of the station to accelerate 14kt of rock with 2m/s² isnt cheap either :P

and vaporising rock at all isnt hard, that i can do with a thing i can buy off the shelf for a few ten thousand bucks :P
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Re: Post Your Favorite Sci-Fi Concept Art

Postby JanB1 » Tue May 16, 2017 2:24 pm

Oh God. What have I done! :lol:

Okay, cool down everyone.

@Trigger: You system is a cool Idea, but I too think one (1) Laser is more efficient. You don't need to vaporise kilogrammes of rock, you just need to heat a small area for a few milliseconds. If done repeatedly you can change the trajectory of these asteroids, so they will miss the station. Maybe just barely, but they will miss it. And you can turn the station with the help of gyroscopes, so you really only need one laser and a few capacitors that enable this laser to fire a few times for a few milliseconds with a massive amount of energy.
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Re: Post Your Favorite Sci-Fi Concept Art

Postby Cornflakes_91 » Tue May 16, 2017 2:27 pm

JanB1 wrote:Oh God. What have I done! :lol:

Okay, cool down everyone.

@Trigger: You system is a cool Idea, but I too think one (1) Laser is more efficient. You don't need to vaporise kilogrammes of rock, you just need to heat a small area for a few milliseconds. If done repeatedly you can change the trajectory of these asteroids, so they will miss the station. Maybe just barely, but they will miss it. And you can turn the station with the help of gyroscopes, so you really only need one laser and a few capacitors that enable this laser to fire a few times for a few milliseconds with a massive amount of energy.


well, you do need to vaporise rock, just not much.
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Re: Post Your Favorite Sci-Fi Concept Art

Postby JanB1 » Tue May 16, 2017 2:43 pm

Cornflakes_91 wrote:
JanB1 wrote:Oh God. What have I done! :lol:

Okay, cool down everyone.

@Trigger: You system is a cool Idea, but I too think one (1) Laser is more efficient. You don't need to vaporise kilogrammes of rock, you just need to heat a small area for a few milliseconds. If done repeatedly you can change the trajectory of these asteroids, so they will miss the station. Maybe just barely, but they will miss it. And you can turn the station with the help of gyroscopes, so you really only need one laser and a few capacitors that enable this laser to fire a few times for a few milliseconds with a massive amount of energy.


well, you do need to vaporise rock, just not much.


Yeah, that's why I said you don't need to vaporise kilogrammes, just heat a small area (to a very high temperature). :D
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Re: Post Your Favorite Sci-Fi Concept Art

Postby Triggerhappy » Tue May 16, 2017 4:56 pm

Response of idea owner: "with electric motors you spend energy to accelerate and then recuperate 90% ja that energy to stop. it also allow to rotate station in any direction without propulsion system"
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Re: Post Your Favorite Sci-Fi Concept Art

Postby Cornflakes_91 » Tue May 16, 2017 4:58 pm

Triggerhappy wrote:Response of idea owner: "with electric motors you spend energy to accelerate and then recuperate 90% ja that energy to stop. it also allow to rotate station in any direction without propulsion system"


Which still doesnt remove the fact that you are jerking around fifteen kilotons of rock because you dont want to be sensible :P
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Re: Post Your Favorite Sci-Fi Concept Art

Postby Triggerhappy » Tue May 16, 2017 5:25 pm

Sensible enough if you don't want to put lasers on your storage station. And, still, there is that very nice 90% or so recuperation factor.
Don't say 'place your stations better' again please because that's not the point of the idea here.

I have also noticed that Cornflakes did not, in fact, mention engines. Apologies. I automatically assumed SOMEONE would say something about engines. How else do you move that compact battle platform you all seem to want out of the way of asteroids.
No orion engines are not acceptable either.

"put it in an orbit where you dont have to avoid rocks every 5 seconds" Still not the point of the idea.


If anyone else wants to offer ideas for dodging stations, I welcome the input.


Edit: more points were made -

recuperated energy can be damn well near 100%, far more efficient than a laser.

It's damn well near impossible to aim at s small pice of rock traveling at you long enough to vaporizer any part of it.

Rocks come in different materials - the same amount of energy fired at it with a laser can do anything from heat it up slightly to shatter it into a lot of small dust that is now coming at you. You won't even know what the mass of the rock is and where to fire to set it off course.

The station can be rotated in all three directions with only 2 arm rails, since the arms are not on one plane, but not like that's needed since asteroids will only be coming from one direction.
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Re: Post Your Favorite Sci-Fi Concept Art

Postby JanB1 » Wed May 17, 2017 1:08 am

Triggerhappy wrote:I have also noticed that Cornflakes did not, in fact, mention engines. Apologies. I automatically assumed SOMEONE would say something about engines. How else do you move that compact battle platform you all seem to want out of the way of asteroids.
No orion engines are not acceptable either.


Well, we TURN the station with the help of gyroscopes and don't NEED to MOVE it, because we move the asteroids instead of the station. That is our point.

Triggerhappy wrote:recuperated energy can be damn well near 100%, far more efficient than a laser.


Yeah, yeah, recuperation factor is nice, and lasers don't recuperate any energy they fired. But how much energy do you need in the first place?

Triggerhappy wrote:It's damn well near impossible to aim at a small piece of rock travelling at you long enough to vaporise any part of it.


Again, we are talking about the far future where we have space stations like this idling somewhere around, and we're talking about MILIseconds. I think it's not THAT hard to aim at a piece of rock for a few milliseconds.

Wait a second...what size of rocks are we even talking about here? I'm assuming >1m?


Triggerhappy wrote:Rocks come in different materials - the same amount of energy fired at it with a laser can do anything from heat it up slightly to shatter it into a lot of small dust that is now coming at you. You won't even know what the mass of the rock is and where to fire to set it off course.


And that's why you use pulse lasers. You fire small burst until the desired effect is reached.
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