96 replies to this topic

[Suskis]

The whole idea of a fusion reactor put inside a mech is quite silly. A single screw out of place and the whole magnetic torus would collapse, melting down the mech and exploding like a supernova. Mechs are expected to receive missiles and particle beams.. Not the safest use for a walking sun.

[Mason Grimm]

Suskis, on 10 April 2012 - 05:31 AM, said:

..... Not the safest use for a walking sun.

[Karel Spaten]

Suskis, on 10 April 2012 - 05:31 AM, said:

The whole idea of a fusion reactor put inside a mech is quite silly. A single screw out of place and the whole magnetic torus would collapse, melting down the mech and exploding like a supernova. Mechs are expected to receive missiles and particle beams.. Not the safest use for a walking sun.

I imagine the same logic applies as that of the nuclear fission reactors powering the USS Nimitz...

[Peiper]

chewie, on 09 April 2012 - 10:32 AM, said:

Hmm, I'm not sure if your trolling or serious........

See the final book in the Blood of Kerensky trilogy, when Phelan is facing off against Vlad, and Phelan says to himself how Vlad cannot use both gauss rifles at once, because of the power drain on the mechs reactor (or words to that effect)



Oh wait, you weren't trolling or being serious......


oh no!!!!!, that makes me the Trollololollooolll!!!!!!!!!!!!!

During Phalen Kell Wolf's first Trial of Position, the third mech he faces off with is Vlad's Executioner. The first time Vlad Wolf shoots at Phalen's mech, he fires only one Gauss Rifle, then the other shortly after, but fails to shoot the rest of his formidable arsenal. Phalen at first thinks Vlad is steadily shooting one weapon at a time to torment and dissect him. Then he remembers some advice he heard earlier when issued his Lone Wolf for the trial.

"Vlad isn't in control. Natasha warned me about the power requirements for a Gauss Rifle. Vlad hit the triggers for everything in his first shot. He's got the Gauss Rifles set up as the primary weapons, so they get the first crack at the power from his fusion engines!"

Because this thread is all about being a know it all, I had to throw this in: This is in the Second book of the Michael Stackpole's Blood of Kerensky trilogy: Blood Legacy on page 152.

[Suskis]

Karel Spaten, on 10 April 2012 - 06:08 AM, said:

I imagine the same logic applies as that of the nuclear fission reactors powering the USS Nimitz...

Actually, an air carrier fission reactor hit by a missile just breaks down and sinks in water, cooling down and polluting the environment forever. Yes, it's still silly and terrifying, but war is not smart per se.
However, the equivalent of a walking a-bomb is a lot worse, imho.

Edited by Suskis, 10 April 2012 - 06:22 AM.

[NoElf]

Victor Morson, on 09 April 2012 - 09:38 AM, said:

Why yes, that SRM-2 gives "serious close range punch!"

Oh this reminds me of the Mechcommander Intro and then some!

[Max OConnor]

I think my favorite thing in here is that if you actually fixed / accurately represented physics and real life science as we understand it today in a computer game / TT game, these people opining for more realism would not play.

Scenario: Ok guys, you are just about to hot drop into your LZ from orbit. You are all loaded up in your assault mechs and you are ready to kick some butt. The dropship doors open and you eject. ..................oh on the way down an ICBM blows you to bits, your character is dead and the planet is still under the control of the enemy.

MAN that was SOME FUN HUH????

Or maybe, you've landed and you are heading to the last known enemy encampment. Suddenly you are shelled from 6 miles away by heavy artillery and you blow up and die. Yet another GREAT GAME right?

The only giant robot game that even comes reasonably close to RL is Heavy Gear, and in that game Tanks rule, Gears are more versatile but the biggest assault gear is a baby compared to a small tank.

Face it people, if we wanted realism we wouldn't be playing in giant robots.

[Maester]

2Peiper
That is an argumented statement, with references and all:) Getting hats off!

About the fusion power... Maybe few hundred years ago ppl spoke smth like that about steam engines:) Ooo, it can blow and scald you to bones! It is safer to ride on true and tied horses (or on those rickshaws).
As Karel Spaten mentioned, we use today fission furnaces on some vehicles (ships, submarines, we even had a fission power plant proposed for satelite) for if you can get advantage the risks will rarely stop you - currently the employment of fissin engines on ships allows them to operate MUCH longer without support then any ICE engine would.
On top of this, the fission reaction is self sustaining and if left unchecked will go faster and faster... then it will yeild a termal explosion and spill the radioctive melted fuel over the area (exactly what happend in Chernobyl, and what has been averted with unhuman effort in Japan recently). Bottom line - to shat down fission reactor you must apply more effort then it took to start the reaction.
With the fussion reactor (of any currently proposed "hot" type) you must take enormous effort to start the reaction, and then nurture it for it not to collapse... so it is much safer then fission reactors, including radioactivity problems but that is a whole another story.

2those who still confuse Gauss and Rail types of accelerator
Those things are fairly well written even on the wikipedia, principal schematic included - and they ARE different, completely. Stop intermixing those things, unless for the trolling purpouse:)
Railgun prototypes seem to be already here in now days alas the problem of "oneshot" is far from been solved (effectively the shot puts so much wear on the "barrel" that it must be trashed outright) as well as the size of power station to fire is size of a warship:)
The closest thing we have today to the gauss/coil gun are maglev trains being prototyped and tested. Although it is not the same as gun, it utilizes same principals. The problems here, beside power usage, are with the finess - you need tight control over those magnets, hundreds of them, which is much harder then just switching them on and off.

2Killashnikov
Although your post is right, the Kartr was basicaly right too, for the heat sinks in BTT are described as been conduction/convection type with Laser Heat Sinks been a separate device set further down the timeline.

[Kartr]

Maester, on 10 April 2012 - 05:23 AM, said:

2Kartr
Although I consider your post reasonable, I would disagree with your take on the operation of fusion engine. Sticking to the sought that if fusion engine is intakt it not only generates zero waste heat, it also can eat some of the waste heat from other systems... is sustained by the rules on Heat Sinks which allow up to 16 (based on the rating of engine) to be placed "into" the reactor. The book says that those feed the heat back into the core (if someone can, please, quote this paragraph).

As I recall the amount of HS on a fusion engine is limited to 10. I am going to quote someone elses post about fusion engines and how they work because it does it more eloquently than I could. Suffice to say that fusion engines create heat, its the fundamental nature of fusion reactions.

Killashnikov, on 10 April 2012 - 04:59 AM, said:

Fission reactors and Fusion reactors operate on the same principle as a coal fired power station, the only difference is the source of heat to create steam (and in the case of fission reactors, the containment required to keep the radioactive by-products away from the environment.) In Fission the heat comes from atom decay, in fusion, it is created by the tiny amount of mass lost when larger atoms are created by mashing smaller ones together. To create more power it is necessary to raise the temperature of the core in order to generate more steam to drive the turbines which drive generators which provide electrical power.
Even assuming a completely different reactor design, the energy of a fusion reaction is released as heat, and this heat is essential to maintain the reaction. In fusion reactions, if you allow the core temperature to drop, the chain reaction will collapse.
Therefore as more energy is required from the reactor, the reactor must generate more heat.

Maester, on 10 April 2012 - 05:23 AM, said:

The heat we get on our hands by running around (all the mooving) is generated by the myomers which need high current to operate while having high ohmic resistance (which also can be quotated from the rule book). So it makes them into a good tubular heating element.

Except according to the rules walking only generates 1pt of heat and running generates 2pts of heat. On the other hand firing your lasers, PPCs and other weapons generates much much more heat. For the energy weapons that heat is because you're asking the fusion reactor for more energy and so it has to burn hotter and fuse more material to provide the power you're asking for.

Maester, on 10 April 2012 - 05:23 AM, said:

For the other points...
Your explanation on heat sinks is very good:) I always wondered how a radiator would help you in vacuum, so unless you have some matter to evaporate on you your mech is limited to those sinks on your reactor. There are those experimental laser heat sinks, but they are well ahead of our timeline here (but I would have given some to behold an overheated jade phalcon with partial wings and those).

The heatsinks "in" the engine work the same way as heat sinks you add to the 'Mech (according to the rules and fluff) they dissipate heat into the surrounding environment. So in a vaccuum the only place for them to send heat is into the 'Mech itself. This means you're actually going to see waste heat dumped into structural members and armor and other components if you're fighting in space.

Maester, on 10 April 2012 - 05:23 AM, said:

As an offtopic...
I would also disagree with the list of realistic settings (if we drop the term realistic for a more soft "plausible"): star trek's "tech" is way more plausible then swars, even more so if we overlook all those things that made it in due to film budget issues. And here in BTT we dont have those film issues, although some authors did some worsening:) And for the magic and all... pahhh. Just drop it:)

Except if you read through the Star Trek Technical journals they have all sorts of made up materials (whether or not there are islands of stability is largely irrelevant) which allow them to do scientifically impossible, or at least implausible things. Dilithium crystals are just a magic power crystal, sure they make up stuff about how its "porous to anti-matter" and other similar sounding explanations for any of the many other made up materials they use to achieve the impossible. Sometimes these even sound somewhat scientific, but stripped of the pseudo scientific words it all boils down to "magic."

[Sgt Kartr]

Space filling post so I don't get a "too many quotes" error when I post the second half from my main account.

[Kartr]

Killashnikov, on 10 April 2012 - 05:30 AM, said:

Actually I am sorry to say you have this slightly wrong. Temperature is the measure of heat energy stored in a substance. Not its rate of transfer. Heat is a form of energy which is the kinetic energy of individual molecules moving in a substance.

I never said "rate" I merely said temperature is the change in the energy of a system. But yes I'll agree that temperature is the measure of energy in a system, I guess what I was trying to say is that heat is the difference of energy between systems and got heat and temp mixed up because it was late.

Killashnikov, on 10 April 2012 - 05:30 AM, said:

As temperature increaces the kinetic energy of the molecules increaces. These molecules in turn convert this energy to radiation which they emit as light in direct proportion to their temperature. As the temperature increaces both the amount of radiation and the peak frequency of the light given off increaces.
At room temperatures these frequencies of light given off are below visible light in the infra red range.
As temperature increaces to around 500C the light becomes visible and substances glow "red hot".
As this increaces still further the light given off becomes brighter and whiter (incandescent light globes).
Sufficiently hot objects such as the corona of our sun and plasma give off light above visible spectrums - Ultra Violet. Taken to extremes, such as in nuclear detonations, the temperatures get high enough to give off x-rays and gamma rays.

Somewhat correct, its not happening at the molecular level its happening at the atomic level. The make up of an atom is roughly like that of an onion with multiple layers. At its heart you have the nucleus made up of positively charged protons and neutrally "charged" neutrons. The electron shell has multiple "levels" and multiple types of "levels" when a sufficient amount of energy is pumped into an atom the electrons "jump" up to a higher energy "level" and then drop back down. When they drop back down the release that energy as light.

So light and heat are both dependent on how much energy is input into a system but they happen at different resolutions. "Light" is generated on the atomic or sub-atomic level and heat is generated at the molecular level. Anytime you generate light by pouring energy into an atom you're also going to generate heat because the atom is going to move around faster and faster the more energy you pump in.

Killashnikov, on 10 April 2012 - 05:30 AM, said:

In a vacuum, hot objects can radiate away massive amounts of heat as light.

They cannot radiate any heat away in a vacuum because heat is the difference in temperature of two systems. They can radiate energy away by emitting light and decrease their over all energy(temperature) that way, but for their to be heat there has to be physical contact with other molecules to transfer the kinetic energy from the molecules of the 'Mech.

Killashnikov, on 10 April 2012 - 05:30 AM, said:

In fact a house fire can induce fires in other objects at quite some distance, despite almost all of the conducted energy travelling straight up. In nuclear explosions, the light given off by the chain reaction can light fires several kilometers away well before the blast front reaches the same point.

Most of the conducted energy is carried upwards because as the temperatures heat the surrounding atmosphere and it increases the pressure of the gasses and they have to move higher into the atmosphere where the pressure is lower so they can expand to a volume that they require based on PV=nRT. However there is still a tremendous amount of energy being pumped out in all directions as the fire heats the surrounding molecules and if there are any items with sufficiently low reaction energy requirements then they will combust because of the extra energy transferred via conduction through the air.

I believe the light from an atomic explosion can ignite fires because the energy being released as light is many orders of magnitude greater than the light energy of a house fire.

Killashnikov, on 10 April 2012 - 05:30 AM, said:

In practice, on earth, in an atmosphere, most heat sink systems are designed to operate at low temperatures using primarily conduction/convection to remove heat.

This is the kind of heat sink BattleTech uses.

Killashnikov, on 10 April 2012 - 05:30 AM, said:

In theory however there is no reason that a heat sink system could not be designed to concentrate sufficient heat in a radiator fin to allow heat to be lost through radiation out into a vacuum.

Laser heat sinks have been proposed which convert heat to light which is chanelled out as a laser beam.

I guess they eventually get them down the time line, but to me these sound very inefficient for most situations. Unless the environment is such that you cannot radiate waste energy into the surrounding atmosphere using conduction/convection it doesn't make sense to increase the energy to the point where you're actually emitting light.

Killashnikov, on 10 April 2012 - 05:30 AM, said:

It would make far more sense though to channel this heat back into the reactor for conversion back into electrical power.

There are also substances which are able to convert heat directly into electricity. Most modern electrical thermometers use this property to measure temperature. Clothing has been proposed which could charge your phone using the temperature difference between your body and the environment.

Lets be honest, even today there are many ways to make heat sinks work in a vacuum, and this game is set in a future where a fusion reactor can weigh half a ton...
Is it a detailed simulation? no. But as a shorthand system to explain a technology which does not exist it works ok.

Well that's why we're discussing it in the "broken logic" thread. As for heat sinks in vacuum, impossible since there is no heat in a vacuum. However is are their ways to radiate waste energy in a vacuum, definetly.

[Maester]

2Kartr
Definetly not just 10:) Though it is most of the time 10. I will provide the table inside the spoiler (columns - rating, weight class, supported heat sinks):

Spoiler

10 0,50 0
15 0,50 0
20 0,50 0
25 0,50 1
30 1,00 1
35 1,00 1
40 1,00 1
45 1,00 1
50 1,50 2
55 1,50 2
60 1,50 2
65 2,00 2
70 2,00 2
75 2,00 3
80 2,50 3
85 2,50 3
90 3,00 3
95 3,00 3
100 3,00 4
105 3,50 4
110 3,50 4
115 4,00 4
120 4,00 4
125 4,00 5
130 4,50 5
135 4,50 5
140 5,00 5
145 5,00 5
150 5,50 6
155 5,50 6
160 6,00 6
165 6,00 6
170 6,00 6
175 7,00 7
180 7,00 7
185 7,50 7
190 7,50 7
195 8,00 7
200 8,50 8
205 8,50 8
210 9,00 8
215 9,50 8
220 10,00 8
225 10,00 9
230 10,50 9
235 11,00 9
240 11,50 9
245 12,00 9
250 12,50 10
255 13,00 10
260 13,50 10
265 14,00 10
270 14,50 10
275 15,50 11
280 16,00 11
285 16,50 11
290 17,50 11
295 18,00 11
300 19,00 12
305 19,50 12
310 20,50 12
315 21,50 12
320 22,50 12
325 23,50 13
330 24,50 13
335 25,50 13
340 27,00 13
345 28,50 13
350 29,50 14
355 31,50 14
360 33,00 14
365 34,50 14
370 36,50 14
375 38,50 15
380 41,00 15
385 43,50 15
390 46,00 15
395 49,00 15
400 52,50 16

Sorry for the messy table - it is exported from my personal notes saved in excel.
As for the reactor, I seem to get the root of our misunderstanding. You refer to the fusion engine concept that uses fusion furnace as a mean to power some kind of other device, ex. turbine (like the fissions currently do), to make power... which is not only inefficient, but also dimed impossible. The reason for it been that to contain the power of reaction you will need 90-97% of the energy generated by the reaction itself - with the inherent inefficiency of turbine it will not even be able to contain/susteain the reaction:) There are those other concepts which include using some kind of "target" which is hit by the energized particles taken from the core to generate electricity directly. Will try to make a reference if I am able to find the article or any other sourth for that thing. (I am not nearly as knowlegable on that stuff as needed to enlighten others). Bottom line is, that energy is derived from energized particle's kinetic energy, not from their radiation heat, so the more particles you drive off the core, the colder it gets.
Also radiation heat sinks are been worked on now days, for on the satelites there is always a problem to dump heat with minimal mass to do the task. So bigger irradiator is bad, carrying gas to evaporate is even worse. The problems here are been solved from two ways (that I am aware of): first is by the use of "heat pipes" or semiconductor materials to gather heat in one place effectively taking energy from lower temperature object to the one with higher temperature, the second is to find materials to lower the treshhold for radiating energy.
As for the other settings, lets just drop it for now for the sake of finding the culprits here in BTT:)

[Silme]

Ghost, on 09 April 2012 - 01:09 PM, said:

Video depicts a railgun. Gauss rifles are coilguns. In short:

Coilguns pulse current to portions of the coil at a time to accelerate the projectile (which is magnetically suspended in the barrel) in short bursts. Each coil lights up sequentially.

Railguns have a conductor contacting both rails that a massive current is driven through, requiring much more power and generating ridiculous amounts of heat from friction on the rails, to the point (current day) that the rails are usually degraded beyond use after one or two firings.

[IceSerpent]

Victor Morson, on 09 April 2012 - 09:38 AM, said:

Flamers - A weapon that draws the heat straight from the fusion reactor and vents it! How it should work is obvious: The hotter your reactor is running, the more potent the damage that can be fueled through your flamer is. Since it's venting heat, it should cause either no heat, or actually lower it. .. except it doesn't. It spikes your heat to dump heat out of your 'mech into the atmosphere. What?

IIRC, all flamers in the novels were of a traditional, fuel-based type. Although, some TRO mentioned the ones channelling heat straight from the reactor. Even the second kind kind of makes sense in terms of heat increase - you increase the heat output of the reactor and try to vent all of it out, but some of that energy transfers to flamer barrel and bumps the overall temperature of the mech.

Quote

Autocannon/20s vs Gauss Rifles - An Autocannon is a big tank canon style shell, like tanks today use. A Gauss Rifle is similar to a rail gun, taking mass amounts of energy to accelerate a solid metal slug at it's target. Which is why the Gauss Rifle doesn't use the reactor hardly at all while the Autocannon costs huge heat spikes, of course.

The "reload" of gauss rifle involves charging the capacitor bank (slowly), heatsinks have ample time to dissipate heat generated during that process. AC uses explosives to accelerate the shell, which heat up the gun barrel (almost instantly), which in turn heats up the mech.

Quote

Pulse Lasers in no way would look like "streams of ruby darts", fluff writers!

Yeah, I prefer green darts too

Quote

Clearly, if it's 50 degrees or 80 degrees out will make a huge impact on the heat inside of a fusion engine. Of course if you put your heatsinks into a vacuum, they'll clearly work really, really well!

Heat transfers via radiation as well as via convection. Heatsinks will still work in vacuum, and if that vacuum is outer space, lack of convection will be balanced by increased temperature difference.

[Maester]

Heee Hee! Now this is a troll target! Silly statement:)

IceSerpent, on 10 April 2012 - 11:56 AM, said:

Heatsinks will still work in vacuum, and if that vacuum is outer space, lack of convection will be balanced by increased temperature difference.

You must be hardcore, and have skiped school for that reason:)
Temperature difference in vacuum. Lol.
1. Temperature is a property of matter, and the vacuum has none of it by the definition;
2. Heat transfer via radiation does not involve temperature difference anyway;
3. Convective heat transfer (and also the conductive one) do benefit from the temperature difference (it is refffered as "thermal head"), but you said yourself that we have no such thing in vacuum (at least you know that).

As far as todays technology belives you cannot have radiator to be both effective at convective and irradiative heat transfer for the former requires rough surface, and the latter polished one.

[The Smith]

Weapon ranges in BT show a total lack of understanding where ballistics are concerned. This bothers me more than anything else. But a lot of the cannon is a bit off in terms of actual science. That said all of the cannon was built around a board game. Realistic ranges would require a really big table.

[Sug]

http://imagine.gsfc....ers/970603.html

Paraphrasing.

The Question
How would the unprotected human body react to the vacuum of outer space?


The Answer

From the now extinct page http://medlib/jsc.na...ro/vacuum.html:

Yadda yadda....exposure to vacuum causes no immediate injury. You do not explode. Your blood does not boil. You do not freeze...
...You do not instantly freeze because, although the space environment is typically very cold, heat does not transfer away from a body quickly.





I'm taking this to mean that you would still lose heat in space, but you wouldn't instantly freeze. So the mech would still lose heat eventually. Though i think what someone said earlier about how the heatsinks would just transfer the heat to the whole mech rather than dissipate it is true.

Even though space is "cold" if you have no molecules the concept of temperature is meaningless.

Edited by Sug, 10 April 2012 - 12:59 PM.

[IceSerpent]

Maester, on 10 April 2012 - 12:28 PM, said:

Heee Hee! Now this is a troll target! Silly statement:)

You must be hardcore, and have skiped school for that reason:)
Temperature difference in vacuum. Lol.
1. Temperature is a property of matter, and the vacuum has none of it by the definition;
2. Heat transfer via radiation does not involve temperature difference anyway;
3. Convective heat transfer (and also the conductive one) do benefit from the temperature difference (it is refffered as "thermal head"), but you said yourself that we have no such thing in vacuum (at least you know that).

As far as todays technology belives you cannot have radiator to be both effective at convective and irradiative heat transfer for the former requires rough surface, and the latter polished one.

/facepalm

For those who slept through physics classes like Maester: Temperature difference between the heatsink itself and whatever object one is trying to draw heat from, not betwen heatsink and hard vacuum. In atmosphere heatsink radiates heat and also loses heat due to convection. The convection process is highly dependent on the difference between ambient temperature and temperature of the heatsink itself - when they are equal, you won't dissipate anything through convection. Same applies to conductive transfer between the heated object and the heat sink. Radiation of heat is the same regardless of temp. difference.
So, your mech is planetside with shutdown reactor - your heatsinks are at ambient temperature (let's say 75F). You power it up and fire a PPC, the mech heats up, excessive heat is transfered to heatsinks (subject to conduction if heatsink is bolted to the reactor or that PPC or convection if it uses liquid cooling), the temp. difference between ambient 75F and current mech temp. comes into play. Then portion of that heat is radiated from the heatsink (not subject to temp. diff.) and portion is dissipated via convection (temp. diff is in play again).
Now, same scenario in outer space - your heatsinks are at zero degrees (whatever heat they had was radiated away long ago). You power up and fire a PPC. Conduction to the heatsink happens much faster because of greater temp. difference. There's no convection between heatsink and surroundings (vacuum), so all heat has to be radiated away.
Whether faster transfer of energy to heatsink (thus allowing it more time to radiate it away) will outweigh the lack of convection (which slows down the dissipation) is a different question, but statement that heatsinks will not work at all is completely false.

[Cochise]

[syngyne]

Suskis, on 10 April 2012 - 05:31 AM, said:

The whole idea of a fusion reactor put inside a mech is quite silly. A single screw out of place and the whole magnetic torus would collapse, melting down the mech and exploding like a supernova. Mechs are expected to receive missiles and particle beams.. Not the safest use for a walking sun.

...fusion reactors don't explode. It is very hard to get an artificial fusion reaction going and sustained in the first place. If the machinery gets damaged you just end up with the reaction fizzling out. You need to specifically design a fusion device to explode if you want it to act like a bomb.