40 replies to this topic

[TheMightyWashburn]

TL;DR? Its a written forum, learn to read more.

MW:O claims to be hard scifi(could be harder) so I figured some of you might want to know about the power system in your mech. Let me say I am not a nuclear physicist/engineer so I may make mistakes and I wont get into any math.

Fission is the splitting of atoms. Usually uranium 235 in power plants. Basically you take your atomic nuclei of uranium 235 which is fairly stable and you smack it with a neutron making it U-236 which is very unstable and quickly decays into several lighter elements, such as Krypto-92 and Barium-141 along with 3 neutrons and a few gamma rays(high energy photons). A clever reader may notice something. You got back all 236 protons and neutrons from the fission products. But you also got gamma rays?! Magix? Nope. Contrary to popular belief fission does not convert any of the particles into energy. So where does it come from? The bonds my dear boy! The strong nuclear force that holds the neuclus together "contain" energy and when you break them you release that energy. The really neat part is that because energy has mass the total mass of the fission products is less than the 1 neutron and 1 U-235. Anyway, so as you can imagine the 3 neutron babies of the first reaction hit 3 more U-235s and the process continues. In the case of a bomb this is left to happen VERY fast. All those gamma rays released by the chain reaction heat things so fast they vaporize (and therefore increase in volume MANY time over) causing an explosion. In power plants this process is slowed with "control rods" that slow the rate of neutron precipitation by absorbing them. The heat created by the gamma rays then heats water and turns it into steam the powers turbines and this is how Nuclear power plants work. (usually) Some other kinds (like the one on the curiosity rover) is a germanium alloy to convert thermal heat into electricity(as I understand it).
MYTH: When a fission reactor melts down it produces a nuclear explosion like the one in Hiroshima.
Nope, usually what happens is the control rods fail to engage or the water gets stopped either of which cause the reactor to get really hot and melt. The explosion comes from the water in the "boiler" suddenly phase shifting into steam which increases it volume several fold, hey! Presto! radioactive steam bomb!

Fusion, as you may have guessed, works the opposite way. Instead of splitting heavy atoms very energetic (hot) light elements such as hydrogen & helium isotopes are combined. As it turns out the two nuclei (lets say two hydrogen atoms, one deuterium(1 proton, 1 neutrons) and one tritium( 1 proton, 2 neutrons) have more energy in their bonds than they "need" and when you fuse them into 1 neutron and 1 Helium-4 the fusion products have less energy in their bonds than did the original reactants which of course is released via high temperature and radiation. In theory the neutron would go on to smash a Lithium-6 into some tritium which would react with the deuterium but there are many many possible combinations and in fact everything up to iron is exothermic when fused (iron is endothermic and generally when a star gets big and hot enough to "burn" iron it died (super nova + core collapse)
Humans have made fusion reactors but none so far that produce more energy than they need to keep going. That could be more than 50 years off. (who knows what singularity tech may produce)

In MW it seems mechs are powered by fusion engines. Sadly they are unlikely to explode because unlike a fission reaction which has several years of fuel waiting to explode a fusion reactor would only feed the perfect mix of fuel into the reactor at one time. If this was disturbed by being ruptured you would see a jet of plasma vent from the rupture for a very short time and then it would stop. In fact it would even be within acceptable limits for radiation by current standards. The only "explosion" you could have would be if the structure of the mech was so damaged that it could not hold the extremely powerful magnets (used to contain the plasma) in place and they would push the engine apart like a huge MRI explosion. They could have this happen like 1/(some number) of times that a mechs CT was destroyed. Though it would do no damage to anyone and probably wouldnt produce more than a small flash of light.

Anyway, I hope you enjoyed your science lesson. Sorry for any mistakes!

[Vassago Rain]

I think you're doing it wrong.

[TheMightyWashburn]

I think you're doing it ignorant. And your picture makes little sense. Part of the whole point of getting DEEP into hard science fiction is using real science + your imagination to create interesting stories. Leave your simplicity at the door.

[Penance]

Here is my thought process, and I'm by no means a physicist, but have a passing enjoyment and interest in the subject.

I view Mech engines like little tiny star generators. Stars in the cosmos typically use hydrogen as their primary source of fuel, combining hydgrogen to helium, and on up the periodic table. Stars are where all the elements in the universe are created, including all the things that make us.

Knowing this, we need to look at how a star dies. As a star creates heavier elements, it needs more and more energy to bind them. Once a star reaches this point, where I think it starts combining carbon atoms to IRON, fusion basically stops. This is when a star dies and starts to shed it's outer layers, and possibly supernova if it is big enough. Now an engine is not this big, so a supernova-like explosion isn't going to happen.

A: where is all this "exhaust" from a reactor going?\
B: a mech is no where near the size of a star. It will have a limited amount of fuel. someone mentioned it before but it escaped my mind, where do mechs get their seemingly endless supply of fuel? Even if they used hydrolsis to seperate hydrogen from water, they still need to carry water.

People say that fusion doesn't explode, yet, when atoms combine, they release energy which I believe is a mini explosion. Also, we have created a hydrogen bomb, which is a fusion explosion STARTED by a fission one.

http://en.wikipedia....i/Hydrogen_bomb


I understand that a mech reactor doesn't explode, fusion reactions need uber uber high temps to work, and a breach lowers that immediately stopping the reaction.

http://en.wikipedia..../Fusion_reactor

Edited by Penance, 13 November 2012 - 01:51 PM.

[TheMightyWashburn]

With modern concept of technology in 3049 I dont think a fusion engine would make any sense. The irony is it will certainly never be like any science fiction / futurism we have. You dont have to take a leap of faith to see where computers will be in 100 years, much less 1000.

[Vlad Ward]

Battletech (and by extension, Mechwarrior) is only hard scifi in the context of the 1980's. As our understanding of science evolves, ideas which could previously pass as hard scifi begin to look like space magic and steam punk. Just take one look at Star Trek TOS's massive, cassette-based computers and Jules Vernes' catapults to the moon and you'll see what I mean.

I honestly don't think there are answers to questions about fuel supply and reaction products. As far as laymen from the 80's are concerned, Fusion engines are "future tech" and are best left as ambiguous as humanly possible while still sounding reasonably plausible to another layman.

That said, I do like the OP. Props from another physics grad.

Edited by Vlad Ward, 13 November 2012 - 01:23 PM.

[TheMightyWashburn]

Vlad Ward, on 13 November 2012 - 01:23 PM, said:

That said, I do like the OP. Props from another physics grad.

D'aww

[Throat Punch]

[James The Fox Dixon]

Morsdraco, on 13 November 2012 - 01:40 PM, said:

snip

I don't like cat girls, so they should all die.

[soarra]

i a big supporter of cat girls.. STOP THE REAL PHYSICS

[James The Fox Dixon]

Keep up with the physics because I hate cat girls. They need to die in a fire!

[Penance]

Morsdraco, on 13 November 2012 - 01:40 PM, said:

who cares about the cat girls

[Tarman]

Giant robots as war machines = all of your science is now invalid. The more IRL you pour onto MWO, the less it holds up. Do not ruin my giant roboting with your dirty facts and science!

[TheMightyWashburn]

Uh uh uh

KE=1/2 M V^2?

[Penance]

Tarman, on 13 November 2012 - 01:54 PM, said:

Giant robots as war machines = all of your science is now invalid. The more IRL you pour onto MWO, the less it holds up. Do not ruin my giant roboting with your dirty facts and science!

If you ever hope to see them in IRL, science is the only way.

[Tarman]

Penance, on 13 November 2012 - 01:55 PM, said:

If you ever hope to see them in IRL, science is the only way.

/A/ giant robot, sure. But to get THESE giant robots involves a thousand years of spacewar and rewriting the laws of the universe. Got to be an easier way than that.

[Psykosis]

Quote

I view Mech engines like little tiny star generators.

sorry, that put me on a tangient about rainbows and unicorns.

[Darth JarJar]

Fun read. One very intersting thing I would like to point out is the statement that "if man can dream it, man can build it". I realize there are limitations there but humor me. We have lasers. We have Gauss rifles (rail guns). The US has developed a PPC (sortof). We now have an instrument very much like a medical tricorder ala Star Trek. We are experimenting with space drives that 'jump' the ship by 'folding space-time'. Who knows what else the future holds. Fusion power plants may be on the horizon. I know I would LOVE one for my workboat! Oh and powered exoskeletons (Elemental armor?).

Edited by von Bremerhaven, 13 November 2012 - 02:06 PM.

[MuonNeutrino]

Penance, on 13 November 2012 - 01:07 PM, said:

Here is my thought process, and I'm by no means a physicist, but have a passing enjoyment and interest in the subject.

I view Mech engines like little tiny star generators....

Stars are indeed natural fusion reactors and as such are definitely worth considering for this sort of topic, but you do have to keep in mind that that doesn't necessarily mean that there will actually be much parallel between them and whatever tech goes into a mech's fusion reactor. The main differences are going to arise because a star's fusion reactions are both contained and induced by the star's own self-gravity. This is why you get the whole daisy-chain of fusion of successively heavier elements - because when one element runs out, the self-gravity naturally causes the temperature and pressure to rise such that fusion of a heavier element can begin. That sort of mechanic isn't going to be present in a mech's fusion reactor; from what little we've achieved with sustainable artificial fusion at present, it's quite likely that a reactor is going to have to be constructed to burn exactly one input fuel (or combination of fuels) into exactly one output.

As far as exhaust, current fusion efforts tend to revolve around a final product of helium, if I recall correctly. In that case,I'd guess the excess probably would just be vented, since it's a gas (and since it's a very *hot* gas, venting it rather than trying to retain it would probably be good from a heat standpoint). While I don't recall it being mentioned, I don't think that mechs actually would have a seemingly endless supply of fuel - presumably somewhere in that engine is/are tank(s) of hydrogen/deuterium/helium-3/whatever that it uses to fuel the reaction and that need to be refilled. Plain old hydrogen, if you can pull it off (deuterium and helium-3 are both easier to fuse), would probably be simplest from a logistics standpoint, since, as you point out, it can be gotten from electrolysis of water. That wouldn't be done on the mech itself, but mech support facilities would presumably have that ability.

[Dirus Nigh]

TheMightyWashburn, on 13 November 2012 - 01:05 PM, said:

I think you're doing it ignorant. And your picture makes little sense. Part of the whole point of getting DEEP into hard science fiction is using real science + your imagination to create interesting stories. Leave your simplicity at the door.