the shape of things to come

misnaming because, really, you guys were using the term correctly.
You grew up with primitive computers that needed heat
sinks to cool their chips. ’Mech heat sinks should be called heat
pumps. Those chips are obsolete and gone, but the term “heat
sink” lingers in Kaumberg’s lexicon. And what’s a real heat sink?
It’s a mass meant to soak up heat. Like the shielding of a fusion
engine. That’s a heat sink.
But BattleMechs generate far too much heat to just depend on
a block of silver to soak heat and slowly radiate it. For whatever
historical reason, the required cooling units on ’Mechs are called
heat sinks and I’m going to call them heat sinks in this discussion,
simply to avoid any confusion.
So, before we talk about heat sink hardware further, let’s look
at the major sources of heat in a BattleMech. Know the enemy
before looking at the solution.
Heat Sources
First and foremost, the fusion engine generates heat, even with
all its effi cient energy conversion. The delicate balancing act of sustaining
fusion often results in a fusion engine producing more energy
than is needed. Since there’s more energy than needed, and
it’s not all converted into electricity, the excess is dumped as heat.
Second, energy weapons are not very effi cient at turning electricity
into laser or particle beams. A heavy laser weapon or PPC
can thus create more waste heat than energy going into the target.
The tubes and breeches of ballistic weapons also need good
cooling in the well-insulated structure of a BattleMech.
Finally, myomers generate quite a bit of waste heat, though
rarely as much as weapons. As I think I mentioned earlier, myomers
are not very effi cient at turning electricity into useful work,
resulting in more waste heat. Incidentally, myomers are also one
of the primary limitations on the temperature a BattleMech can
tolerate. Despite centuries of research, only certain materials can
be used to make myomers, and those materials—particularly the
acti-strandular fi bers—don’t like high temperatures.
Collecting Heat
The fi rst step to getting rid of heat is collecting it. To do this, hotrunning
equipment like the engine and weapons have networks
of cooling tubes built into their frames, like the water jacket in
your groundcar’s engine. Myomers have a distributed network of
coolant lines that look like a computer’s concept of a vascular system.
These coolant lines in turn connect the collection systems to
the heat pumps and radiators that I’ll get to in a moment.
Coolants diff er between heat sinks, depending on the manufacturer.
Oils, chlorofl uorocarbons, water-based solutions, liquid
nitrogen, gaseous nitrogen, gaseous helium and other coolants
are used. No, you won’t see molten metals like the Tharkad City
fusion engine. Those are simply too hazardous in combat.
The coolant is then circulated by a wide variety of pumps. A
lot of modern heat sinks like to eliminate traditional mechanical
pumps and instead use myomer-wrapped fl exible tubing that
pulses the coolants along, which is much more damage-tolerant
than central mechanical pumps. For additional damage tolerance,
the whole network of coolant lines also includes a lot of
cut-off valves to prevent catastrophic loss of coolant.
Dumping the Heat
At the other end of heat sinks are the radiators. To understand
how the heat pumps work, I’m bringing these up fi rst. Now, the
radiators in BattleMechs don’t look all that diff erent from those
on your car or refrigerator. They are networks of fi nned tubing
carrying hot coolant, usually assisted by fans to pump external air
or water over the radiators when those fl uids are available. These
radiators are always hidden under armored grills.
The reason that heat sinks use pumps is because of these radiators
and the laws of thermodynamics. Remember that heat
fl ows from hot to cold. Thus, if the heat sinks were simple coolant
systems like the water pump on your car engine and your
BattleMech ended up in a hot environment, its heat sinks would
carry heat right back into the BattleMech rather than cooling it.
Thus, we come to the heat pumps.
Heat Pumps
Arguably the heart of a heat sink, the heat pump basically
collects and condenses heat until it can be easily dumped overboard,
even into environments hotter than the ’Mech. You can
fi nd plenty of descriptions of heat pumps on air-conditioning ‘net
sites, so I’m not going to describe the physics behind diff erent
types of pumps. A multitude of diff erent heat pumps are used
today, based on the manufacturers—including vapor-compression
systems like your home refrigerator, sonic cooling systems,
magneto-caloric systems and others.
Alternate Materials
Standard heat sink radiators have been using graphite tubing
and fi ns since the dawn of the BattleMech. The graphite’s structure
is carefully arranged for best heat fl ow, and oriented graphite
can have a thermal conductivity about fi ve times that of the
reigning metallic champions, silver and copper. Some Periphery
nations have resorted to using copper for heat sink radiators. But
while these do lose some percentage of performance, such radiators
work better than one might expect, because they make
up for their lower conductivity with thinner construction, as the
metals are tougher than the graphite.
The wonder plastics of the Star League also revolutionized
BattleMech heat sinks. These semi-crystalline polymers, which
are also found in XL engine shielding, don’t quite have graphite’s
thermal conductivity, but they are dramatically lighter. They allow
larger radiators to be constructed for the same mass as standard
heat sinks and give us the famous “double strength freezers.” Unlike
many recovered pieces of technology, it’s fun to note that this did
not come from the Helm Memory Core. The New Avalon Institute
of Science was experimenting with this technology prior to the
Core’s discovery. The Clans, meanwhile, never lost the technology
behind this material and even improved on it by using more crystalline,
which creates a more thermally conductive—but also more
brittle—freezer. The required reinforcements keep the Clan double
strength heat sinks at about the same mass, but more compact.
JUMP JETS
I didn’t really want to get into all the many diff erent optional
items of equipment like weaponry and jump jets, but the
Kaumberg media has been fi lling the ‘net with far too many computer
images of ’Mechs rocketing into orbit to defend us from
bandits, WoBblies, and space monsters. So, I’m making an exception
for jump jets here.
Most notably, jump jets can only operate for short periods before
requiring a cool-down period. They can’t operate continuously,
and certainly not long enough to carry a BattleMech into