27 replies to this topic

[Koniving]

colsan, on 29 September 2013 - 08:47 AM, said:

I considered that, but in MW4, you get a heat readout that goes up to about 10000; this also makes more sense, since 700 K is about 800 Fahrenheit, which would barely melt lead, much less the graphite that the heatsinks are supposed to be made of.

MW4 also allows you to generate double the heat permitted in MW3 and Battletech (computer games i.e. "Mechwarrior 1" before the mechwarrior title) and the Battletech 32 player simulator. It's 150% superior to the rate of MW2 PSX, Titanium versions and expansions, which raised to threshold to 40 for an "Arcade" feel. MW4's threshold before Mektek is 60. (After MekTek I read that they changed it to set limits per mechs but I don't know if it's true or not; I can't get the MekTek thing to run on my computer. But I know I did not like the Spiders flying 400+ meters in the sky and able to change directions on a dime like they are Gundams that I saw in MekPak 4 vids.) The average MW game's "heat point threshold" is 30.

Edited by Koniving, 29 September 2013 - 01:36 PM.

[Sasha Volkova]

Im sorry but this thread is displaying dangerously high amounts of intelligent content compared to that which is considered normal on this forum.

Is this really the MWO forum I am on atm?

[Spokes]

colsan, on 29 September 2013 - 08:47 AM, said:

I considered that, but in MW4, you get a heat readout that goes up to about 10000; this also makes more sense, since 700 K is about 800 Fahrenheit, which would barely melt lead, much less the graphite that the heatsinks are supposed to be made of.

At 10,000 degrees Kelvin, a 'Mech would incandesce well into the ultraviolet range. It would literally glow like a star.



Objects in the general area of the 'Mech -- buildings, trees, people -- would likely exceed their auto-ignition temperature and burst into flames. The auto ignition temperature for paper is roughly 500 degrees Kelvin. The melting point of steel is roughly 1,800 degrees Kelvin, and the melting point for graphite is roughly 3800 degrees Kelvin.

For comparison purposes, the temperature on the surface of Venus is about 740 degrees Kelvin.

BattleMech heat sinks (excluding rare and exotic models like laser heat sinks) are forced heat pumps, operating on the same fundamental principles as the air conditioning system in your home or car. They operate by compressing a gas to high pressure (thereby raising its temperature above ambient levels), allowing said gas to cool down in an external radiator, and then forcing the gas through an expansion valve. This expansion valve causes the gas to cool down as it loses pressure, just like a can of shaving gel or compressed air will get cold if you keep the valve open too long. Internal heat is transferred to this cold gas, and the process repeats.

http://www.sarna.net/wiki/Heat_Sink

Therefore, the physical limitation on a BattleMech's cooling system is how much coolant pressure the compressor can force, and how much pressure the coolant lines can withstand. As the external air temperature increases, the cooling system must increase the high side pressure to compensate-- beyond a certain point the system can no longer do so, and cooling efficiency drops.

Outside of a few specific designs like the Exterminator and Scorpion that are designed to shed heat through their feet, 'Mechs should run hot in a vacuum, as there is no external fluid or gas for the high-pressure radiators to transfer the heat to. They will still transfer heat through EM radiation, but that much less efficient than conductive heat transfer.

[Stomp]

I know some of those words.

[Scurry]

colsan, on 29 September 2013 - 08:19 AM, said:

So you are saying that the mech has a vacuum around it so the air doesn't touch?!

Good for you. I did "waste time" doing the math, and it doesn't work. If you aren't going to crunch the numbers yourself, you have no argument.

I was referring to the point about the temperature that the entire Mech would reach, and thus the pilot. Basically, if the reactor was really at 10000 K, it would first dump heat into the mech&heatsink system - which in turn loses heat to the surroundings. If the temperature of the mech/heatsink system is too high, the pilot's dead.

I'll just use that Newton's Law of Cooling here....so rate of heat transfer is proportional to the difference in temperature and the surface area. The mech system reaches thermal equilibrium when the rate of heat-in equals rate of heat-out. So AdeltaT is equal. Let's try 185K. And take the mech as a cylinder, and the reactor as a sphere. Height of the cylinder as 2r, Since the mech would probably have more surface area than a cylinder, I'll double it.

2*pi*r^2*2r(T-185)=4/3*pi*r^3(10000-T)
T=5092.5
You'd be in a mech with an average temperature of 5000K, and it'd be glowing in visible light! Even if it was only the heatsinks - they'd be a beacon to the entire map.

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How about a nonfictional material that was invented in the early 1970s?


http://en.wikipedia.org/wiki/Starlite

I know it exists. However, heat is pretty bad for anything magnetic - which it has to be in order to act as containment for a fusion reaction. That material's a polymer.

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I want to see that math!

Okay, from here: http://i.imgur.com/5Slu6.png
The Commando is about 9 meters in height, and about 4.725 metres wide. To allow for empty spaces, I'll halve the radius, so I can approximate the dimensions by a cylinder.
pi*(2.3625^2)* 9= 158 cubic metres
It weighs 25 tons. 25000/158= about 158 kg/cubic metre. Water has a density of 1000 kg per cubic metre. Even if we assume only a quarter of that volume is filled, so that 25000/(158/4)=634.5 kg/cubic metre, a Commando would float. So yeah, if physics applied, no underwater maps.

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No; entirely wrong. So incorrect that I am having trouble coming up with words to describe it. In fact, in the future, when someone says something that is so completely wrong that it is going to take 5 times as long to correct as the initial statement, I'm just going to say that it is "Scurry."


That is the most Scurry statement I have ever read.

My fault on this one. I got distracted, and so fixated on Cournot and ideal materials so that I had it in my head for some reason that both water and air would be ideal. Dump that one into the trash can.

Just for my sake, would you mind pointing out exactly which section of the equation pertains to this? If it's not the entropy of the reservoirs, that is.

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Then why don't we have unicorns? Wizards riding unicorns puking rainbows that melt our mechs?

If you throw away the basic laws of physics, then you open the door to whatever ridiculous thing comes up next.

Slippery slope, man. Certain laws of physics may be suspended in fiction, but it still has to pass the common sense test. And unicorns in sci-fi sure don't pass.
[color=#959595]

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I considered that, but in MW4, you get a heat readout that goes up to about 10000; this also makes more sense, since 700 K is about 800 Fahrenheit, which would barely melt lead, much less the graphite that the heatsinks are supposed to be made of.

[/color]

For this one, why does the temperature need to be capable of melting lead? Just wondering.

Also, if all these things were correct, we'd still have to deal with how Inferno ammunition works in lore. Not to mention how much heat heavy ballistic weaponry produces.[color=#959595]
[/color]

[Greyrook]

ahhh. They come for the giant robot battles, they stay for the jargonistic discussions of thermodynamics.

[scJazz]

Yeah... ummm Niko can we get this thread tossed into Barracks?!?

[Macbrea]

Ferro-Fiber is a weave of Ferro-Steel (melting point 1370'C), Ferro-Titanium (melting point 1660'C) and Diamond (3350'C)
Standard armor is made out of Graphite (3652'C melting point) and steel (melting point 1370'C)

Now you can see the melding point is 1370'C before the armor on the mech starts to fall off the mech.
Gunpower explodes at 300'C if not encased in a heat resistance material. It will still explode if it reaches that temperature even if in one.

We know in Battletech the heat scale is 30 points long. And at 19 points of heat there is a 5% chance your ammo explodes. At 28 points, you have a 15% chance of ammo explosion.
For purposes of this we will say that 19 is 300'C due to the fact that ammo is shielded.

300'C / 19 = 15.79'C per heat point. This means that a Mech standing at 95'C by default should be sitting at 6 heat scale. As the radiators on the outside of the mech would do nothing for them.

A mech that fires it weapons and exceeds 30 heat (473.7'C) automatically shuts down. And by our rules if you ever exceed your heat scale by double you automatically explode. (60 x 15.79'C) = 947.4'C

You will notice at this temperature the Steel in our mech is red hot and about to turn to liquid anyways. Any gunpower/explosives on the mech would instantly ignite. Kevlar's Melting point is 900'C, meaning any internal components in the battlemech would go up in flames. Not to mention the internal heat would probably have already cooked the pilot by that point.

So, you are partially correct. Heat sinks don't work quite correctly but apply the above rules to your mathematics and you will find that they aren't too far off reality.