Dead Earth

[BMonnery]

Originally posted by robmyers:
</font><blockquote>quote:</font><hr />Originally posted by BMonnery:
Assuming magic heat disipation (another discussion)

What magic? Where do you think the radiation that builds up on the stutterwarp coils comes from?

More seriously, is this the old reactor cooling problem? Can't the ship just leave the heat behind when it jumps?

I've just had a thought. What happens if a SW ship tries to warp through a dust cloud?

- Rob. </font>[/QUOTE]The problem is that in space conduction and convection don't work, so we need to get rid of waste heat via radiation. The formula isn't kind and at reasonable temperatures we need about 600 square meters of radiator per MW of waste heat.

Once this scientific reality sunk in I wrote these house rules:

I've been trying to work out heat numbers for the 2300AD universe.
For those not familiar with it, it uses a "reactionless" drive, using
quantum tunnelling to move ships at a few % of light speed in real
space. For those familiar with it, the Star Cruiser scale is known to
be broken, so I've kept the scale (2 ls hexes) but upped the turn
time to 20 minutes to fit.

The ships of 2300AD do not have large extendable radiators. Making a
few leaps, I used the hull as a radiator, allowing it to heat upto
about 400K ISTR, the upshot was you dumped 1MW of heat per 600 m2 of
hull, or 12 hull points (assuming hull points = material value of the
hull).

For storage, it's known that the power plants also include the heat
loops etc. I just mandated a % of the power plant was coolant. The
other heat management system (only found on warships) were hull
radiators. These reduced signature by selectively radiating the heat
away from the enemy. The upshot was you got 1MW-turn of heat storage
per 2.5 m3 of power plant and 0.5 m3 of radiator.

This leads my to an example, the American Kennedy class Missile
Cruiser. The reactor can generate 150MW, she can store (5000/2.5
+450/0.5 = ) 2900 MW-turns of heat, or about 19 turns at full power
before saturating the storage capacity. She can radiate out about 5
MW per turn.

Now, once this is reached making some assumptions I got the number
that each MW of power will heat the ship 1 degree per 40 tons of
total ship. Thus a Kennedy will heat up by about 5 degrees per turn
once the heat storage capacity is reached.

I then needed a table of the effects of the heat. Since obviously
heating up the ship effects the crew, passive sensors (which need
cooling), electronics and capacitors, I devised this table:

Heat State Effect
+5 degrees CQ reduced by 1
+10 degrees -1 to hit, passive sensors reduced to 3/4
+15 degrees -2 to hit, CQ reduced by 2, passive sensors reduced
to 1/2
+20 degrees -3 to hit, passive sensors reduced to 1/4
+25 degrees no energy weapons may be fired, CQ reduced by 3,
passive sensors do not function
+30 degrees crew incapacitated
+40 degrees crew killed

Does this look about right?

Also, how throttlable is a fusion plant? Can I bring it back to the
3% needed for the Kennedy to cruise at 5MW (about warp 1.5)?

Comments?

Re: dust clouds, since the charge seems to be caused by concident matter, a dust cloud would increase the charge to cross that area (adventure seed?)

Bryn

PS Yes, I know I've assumed 100% efficiency.....

 

[robmyers]

Originally posted by BMonnery:
For those familiar with it, the Star Cruiser scale is known to
be broken, so I've kept the scale (2 ls hexes) but upped the turn
time to 20 minutes to fit.

Blah blah blah article blah blah blah.

The ships of 2300AD do not have large extendable radiators. Making a
few leaps, I used the hull as a radiator, allowing it to heat upto
about 400K ISTR, the upshot was you dumped 1MW of heat per 600 m2 of
hull, or 12 hull points (assuming hull points = material value of the
hull).
For storage, it's known that the power plants also include the heat
loops etc. I just mandated a % of the power plant was coolant. The
other heat management system (only found on warships) were hull
radiators. These reduced signature by selectively radiating the heat
away from the enemy.

I like this, but won't heating up the hull of the ship be a tactical disadvantage if the enemy isn't following the UFP Galactic Up convention?

I'm also sure that a system that can move a starship can move heat. Stutterwarp ships might have an exhaust trail of very surprised electrons in their wake.

Re: dust clouds, since the charge seems to be caused by concident matter, a dust cloud would increase the charge to cross that area (adventure seed?)

But IIRC the ship doesn't displace the space it tunnels into, it superimposes itself. Is that right?

- Rob.

 

[Colin]

Yes, a ship superimposes itself. Even though a dust cloud is still pretty close to a full vacuum, it is still something to be avoided.

As for the heat question, this is how I'm handling it. Yes, I am addressing it. Ships with stutterwarp need a certain amount of hull radiators. They can also use radiator fins, but at a cost in profile and reflected signature. Ships without a stutterwarp (long-range vessels, not landers) require considerably more in the way of radiators. A stutterwarp does act as an energy sink for heat, and effectively disperses it in its wake.

Colin
2320AD writer, and happy to be out of that MS Exchange class

 

[Colin]

Back on the topic of Dead Earth, I once ran a 2300 campaign where Earth had succumbed to a nanotech accident. It wasn't destroyed, but rather, changed. Even the people were altered by the nano plague, and all earthers were part of a common whole, linked through nanotech transmitters, and fervently desiring to bring the rest of humanity into the nanotech fold. Earth is under a quarantine, the remnants of the OQC reinforced by ships from the colonies. My Kafers were a little more like Predators as well, and very dangerous.

Fun game, but didn't last very long.

Colin
2320AD writer, and sick as a dog

PS Don't worry, none of that campaign will find its way into 2320AD.

 

[BMonnery]

Originally posted by robmyers:
Blah blah blah article blah blah blah.

Who reference the article to KevinC in the first place?

I like this, but won't heating up the hull of the ship be a tactical disadvantage if the enemy isn't following the UFP Galactic Up convention?

I'm also sure that a system that can move a starship can move heat. Stutterwarp ships might have an exhaust trail of very surprised electrons in their wake.

Well, detection relies in the emitted power, not temp ISTR.

Surprised electrons? The ship must have a very positive crew

But IIRC the ship doesn't displace the space it tunnels into, it superimposes itself. Is that right?[/QB]

Exactly, so atoms of hydrogen are constantly finding their way into the ship. Sometimes they'll react with matter and some weird effects will ensue. Both KevinC and myself agree this is the root cause of the stutterwarp charge.

Bryn

 

[GJD]

Forgive me if I'm just being dense, but it seems to me that heat build up it shouldn't be a poblem.

Fisson and Fusion reactors basically produce heat, you then have to turn the heat into power (electricity, I'm guessing, unless the stutterwarp is a profoundly complex mechanical device . Turning that heat into power is the basic conversion question, either some kind of advanced direct conversion method has been found, or you use a turbine or simmilar. Reactor superheats liquid, liquid turns to vapour, vapour turns turbine, turbine makes electricity. The heat output of the reactor is therfor directly converted into power for the ship. The vapour has to condense back into a liquid, so you'll still ned radiators to facilitate that, but it seems to me that the actual act of conversion will change a lot of that thermal energy into kinetic (the turbine) and then electrical, to power the stutterwarp. Or did I get completely the wrong end of the stick?

G.

 

[mike wightman]

The problem is the efficiency of each stage of the energy transfer process. Every time the energy is "changed" from one form into another some energy is lost, as waste heat (heating the machinery and then the surroundings) and sometimes sound.
This heat that is wasted at each stage can add up to quite an amount. In a modern nuclear reactor efficiencies of between 40-60% can be achieved.

 

[BMonnery]

Originally posted by GJD:
Forgive me if I'm just being dense, but it seems to me that heat build up it shouldn't be a poblem.

Fisson and Fusion reactors basically produce heat, you then have to turn the heat into power (electricity, I'm guessing, unless the stutterwarp is a profoundly complex mechanical device . Turning that heat into power is the basic conversion question, either some kind of advanced direct conversion method has been found, or you use a turbine or simmilar. Reactor superheats liquid, liquid turns to vapour, vapour turns turbine, turbine makes electricity. The heat output of the reactor is therfor directly converted into power for the ship. The vapour has to condense back into a liquid, so you'll still ned radiators to facilitate that, but it seems to me that the actual act of conversion will change a lot of that thermal energy into kinetic (the turbine) and then electrical, to power the stutterwarp. Or did I get completely the wrong end of the stick?

G.

No you didn't. However, the ship is a closed system, and energy must leave somehow. Even assuming that the energy that goes into the stutterwarp disappears, the efficiency of each stage quickly adds up.

IMC The power was needed to spin the drive coil. The inner core of the drive has like a reserve dynamo and spinning faster meant longer individual leaps. i.e. virtually every joule of energy ends up as heat needing to be dumped.

I can live with the drive power ending up as gravity waves, as the superimposed virtual space of the ship harms the fabric of space-time (a ships wake distorts space-time for several minutes, and is a gravity wave source in canon). However, there's the question of efficency.

With superconductors, 50% is achievable over the whole ship. Meaning that the produced electrical power can be fed directly into the equation for dumping heat.

Of course, you can ignore the problem and carry on, but I like the tactical nuances it psoes for warships.

The open cycle of the MHD allows you to ignore it for civvies. (The heat is ejected with the fuel products)

Bryn

 

[GJD]

Ahh, I see now. I hadn't factored in waste heat and innefficent conversion (Planetology and geology I can do, physics, on the other hand, often baffles me).

I figured MHD and fuel cell would be different.

But, it raises an interesting question. If I have a 5MW stutterwarp, what is that 5MW actually used for? How does the drive actually use the power? I can see some of it would be for support equipment (cryogenics to get the coils near absolute zero or somesuch ancillary equipment), but what about the rest? The actual process of displacment obviously requires a power input, but for what? IIRC CT had the ship dumping deutirium, which was energised by pouring power through a hull grid, so I can see a need for fuel consumption and drive power there, but at the moment the Stutterwarp appears to be a sealed box with a just plug comming out of it to plug into the power grid.

G.

 

[BMonnery]

Changing Gravitational Potential Energy?

IMC it was spinning the coils, as I've mentioned.

MHD Turbines throw out water vapour and can dump heat that way. Fuel Cells are different, as they can recycle their water back to hydrogen and oxygen.

Bryn

 

[jwcarroll60]

Nasty science! We hates nasssssty science we does. Gets in the way it does.