Perfect Adventuring starship?

[aramis]

Interesting site, thanks! However, I still don't believe you could detect the difference between the Rock and a real asteroid if the crew was serious about hiding. Drive signatures are what gives you away.

The adventure did point out that it would look suspicious if the Rock was not in an orbit or on a trajectory normal for asteroids. But this is detective work, not detection.

A rock of radius R around a star of brightness B (in multiples of Sol) at orbital distance D (in AU) has B1367πR²/D².

A ship with a 250MW powerplant in use, assuming an absolutely perfect conversion to energy and no waste heat in the plant (patently improbable to approximately 1/∞), still has 250MW of energy converting to heat by use for non-radiation non-locomotion systems.

Inactive humans run 70-120W, typically; active humans up to 3000W.

Given the average asteroid is at 2AU, a 10m radius asteroid runs around 107kW solar input, and will be at equilibrium, so it radiates that, as well.
Once converted to a "ship," it adds at least 250MW –– a 1Td PP and an engineer –– for 250.107MW... a jump in radiated energy of x2500.

Note that, at a cold start (solar input only) equilibrium won't be reached for several days... but it will NOT be a shirtsleeve environment for most of the first day or two. And a warm drive shut-down will not cool to equilibrium for several days, and will no longer be shirtsleeve for the last day or two. So, if keeping it in the warm zone, you are radiating several times the solar input, as you've raised temp above freezing (and most asteroids are below water freezing point).

 

[Whipsnade]

Still not convinced.

Seeing as we're currently using IR scans to roughly date the impact craters on larger planetoids thanks to relatively minute temperature differences, whether you're "convinced" or not is of no consequence.

The math Wil posted is very clear. Absent a magic heat sink, inhabited ships in Traveller are going to shine like IR beacons.

 

[Strummist]

Yeah, in any real universe Rock isn't stealthy at all, providing that it's trying to hide from sensors above WW2 spec, given sensors in all directions. The only way it could work would be to have a hot side away from the enemy (far trader's post links to a site that convincingly shows Rock would need a large, unwieldy radiator). I suppose something could be done using a remote laser cooling device (which would itself be detectable?). I keep wondering about high-tech impossibilities such as perfect insulators, computational cooling and better than black-body radiators, probably not convincing for the real world, but a kind ref could hand-wave it for the players I guess.

It's still a cool ship, if you'll pardon the pun.

 

[Tobias]

If you want any semblance of stealth, the better option is to hide near, or if possible in, something big that emits or reflects enough heat that your powered-down ship doesn't make for a detectable difference. SDBs hiding in Gas Giants or oceans is the right idea.

 

[Garyius2003]

I disagree. In addition to jump, grav, and reactionless drives, Traveller also has a method of pumping heat somewhere. Every ship is based on this fourth piece of magic (high tech not yet invented).

That being said, gas giant hiding for the win.

 

[far-trader]

I disagree. In addition to jump, grav, and reactionless drives, Traveller also has a method of pumping heat somewhere. Every ship is based on this fourth piece of magic (high tech not yet invented).

It does seem strongly implied in some interpretations of the rules. And as I rather like the submarines in spaaaaace play I accept it to a degree.

 

[DaveChase]

There is this small device called a heat capsule (I just made it OK ). It is used to absorb in a certain amount of heat then it is ejected out of the hull. It helps keep down the IR (heat) signature of the ship.

There is your magic device.


Dave Chase

 

[aramis]

I disagree. In addition to jump, grav, and reactionless drives, Traveller also has a method of pumping heat somewhere. Every ship is based on this fourth piece of magic (high tech not yet invented).

That being said, gas giant hiding for the win.

Jump, grav, and reactionless drives are all explicit, there is no explicit mention of magic radiator tech. There is no implication of it, either.

It's a gross oversight, not a "magic tech."

 

[Garyius2003]

There is this small device called a heat capsule (I just made it OK ). It is used to absorb in a certain amount of heat then it is ejected out of the hull. It helps keep down the IR (heat) signature of the ship.

There is your magic device.


Dave Chase

That, and/or the reactionless drive and JD sucks heat off somehow. That would explain GG and ocean and deep system laying low. I figure your idea sounds good, though.

 

[warwizard]

A ship with a 250MW powerplant in use, assuming an absolutely perfect conversion to energy and no waste heat in the plant (patently improbable to approximately 1/∞), still has 250MW of energy converting to heat by use for non-radiation non-locomotion systems.

Inactive humans run 70-120W, typically; active humans up to 3000W.

Given the average asteroid is at 2AU, a 10m radius asteroid runs around 107kW solar input, and will be at equilibrium, so it radiates that, as well.
Once converted to a "ship," it adds at least 250MW –– a 1Td PP and an engineer –– for 250.107MW... a jump in radiated energy of x2500.

Note that, at a cold start (solar input only) equilibrium won't be reached for several days... but it will NOT be a shirtsleeve environment for most of the first day or two. And a warm drive shut-down will not cool to equilibrium for several days, and will no longer be shirtsleeve for the last day or two. So, if keeping it in the warm zone, you are radiating several times the solar input, as you've raised temp above freezing (and most asteroids are below water freezing point).

I disagree that the power plant would be getting run at 250 M/W, If I was going to try sneaking up on somebody using an asteroid ship, I'd first carry it through jump powered down, and have the tender establish the needed vector, and have several weeks under very minimal power usage as the roid does it's impression of a cold rock in space, albiet one with perhaps a little bit of radioactives raising it's surface temp a few thousandths of a degree. In a short term situation there is something called thermal inertia, it will take a decently long time for the heat generated by a few humans in vacc suits and a small PEMS array with a seperate battery for it's power supply to make it's way through a few meters of asteroid material. I'd have the PEMS array buried deep in a tunnel so only the target could "see" my PEMS antenna, and it'd not be powered up till actually in position to collect the intel. In fact for a good intel op there would not be a power plant on the roid, and it would have been prepped years prior, and would be one of the normal roids of the system, and the "crew" would be robotic.

 

[rancke]

I disagree that the power plant would be getting run at 250 M/W, If I was going to try sneaking up on somebody using an asteroid ship, I'd first carry it through jump powered down, and have the tender establish the needed vector, and have several weeks under very minimal power usage as the roid does it's impression of a cold rock in space, albiet one with perhaps a little bit of radioactives raising it's surface temp a few thousandths of a degree. In a short term situation there is something called thermal inertia, it will take a decently long time for the heat generated by a few humans in vacc suits and a small PEMS array with a seperate battery for it's power supply to make it's way through a few meters of asteroid material. I'd have the PEMS array buried deep in a tunnel so only the target could "see" my PEMS antenna, and it'd not be powered up till actually in position to collect the intel. In fact for a good intel op there would not be a power plant on the roid, and it would have been prepped years prior, and would be one of the normal roids of the system, and the "crew" would be robotic.

Meanwhile, regardeless of how your ideal ship does it, Rock is keeping its living quarters at room temperature and is therefore a shining infra-red beacon.


Hans

 

[aramis]

The 250 MW figure is the minimum for a cell of 1Td; note that scale efficiencies (Matching figures from Striker, FF&S, and MT) mean smaller plant cells are inefficient.

The rules in MT and FF&S are pretty explicit that a Fusion PP runs all on or all off, but note as well that after errata, multiple chunks of PP are allowed, so 1Td cells (the minimum for full efficiency) are permissible, even sensible.

So, while you can probably step down the plant, by building it cellularly, you probably can't reduce a Fusion ship much below 250MW. As designed, Rock is more like 2.5+GW...

And you'll be well above comparable blackbody temp even just by having a human-livable compartment.

It's beginning level physics

 

[warwizard]

FF&S TL 15 Fusion power plant minimum volume is .1 Kl @ 6 MW/kl = 600kw. I place the minimum power plant output at the minium size plant, so a TL 9 plant minium output is 2,000 MW, and it ranges down from there to TL 16's 350 kw. This is ranging away from the topic of perfect adventuring ships. For a spy mission adventure the perfect ship is not going to be one that has to be dumping 250 MW of excess heat.

 

[Dragoner]

I disagree. In addition to jump, grav, and reactionless drives, Traveller also has a method of pumping heat somewhere. Every ship is based on this fourth piece of magic (high tech not yet invented).

That being said, gas giant hiding for the win.

True, the hull must be impermeable, for external effects for the most part, otherwise the crew would be killed by solar radiation, fuel skimming, etc. . I wouldn't necessarily call it magic tech, a good heat exchanger could dump the heat back into the fusion core where the radiant energy is turned into electricity.

 

[mike wightman]

You are going to move heat from cold to hot - good luck with violating that particular law of thermodynamics.

 

[aramis]

True, the hull must be impermeable, for external effects for the most part, otherwise the crew would be killed by solar radiation, fuel skimming, etc. . I wouldn't necessarily call it magic tech, a good heat exchanger could dump the heat back into the fusion core where the radiant energy is turned into electricity.

Not really. Physics says almost all work converts to heat or motion.

It also says heat escapes.

So, if you have a LS system running, you've got the total power it needs leaking out the system by both friction heating, and by work losses; further, the capsule of LS-serviced area leaks heat into the surrounds.

Further, a livable (but chilly) 280° kelvin is many times the radiant energy of the 150°-200° kelvin of the average asteroid.

So, just to have the crew not getting sick, you have roughly doubled the blackbody radiation. Adding useful things like atmosphere recirc turns electricity into waste heat... which axiomatically means you're not dumping it back into the plant.

The 250MW minimum is about as low as one could go and have useful gravitic drives, too... and rock has 3 units of PP - roughly 450MW - and needs that much to have the drives on. Even if not thrusting, it needs some significant subset to generate artificial gravity... and that will result in waste heat as well.

So, however much non-locomotive systemry you have functional, it's power need is the absolute minimum waste heat that the hull radiates. Note that even lighting eventually becomes waste heat.

 

[Dragoner]

Some salient facts:

The hull must be impermeable, otherwise the the crew would be cooked, irradiated (which heat is just another form of radiation), etc. . This is solid, there is no way around this fact; otherwise as well we would see focused heat weapons and such.

The fusion plant doesn't generate power by physical work like generating stream for a turbine. So the technological answer is it turns radiant energy into electricity, like with photo-voltaic cells.

The ship can't radiate enough energy as it is (vacuum is a great insulator), so something must be happening. We have heat exchanger technology now, it isn't that much of an assumption that it is far more efficient. Most of the wasted energy today is in heat due to inefficient designs, poor management, etc.; so in the future, they would be looking to recapture that heat and use it for power. Electricity is the easiest to figure in room temperature supercondutors are most likely commonplace, which reduces the heat buildup of resistance; lighting elements and such, probably unknown today, but I doubt it is incandescent. Others it just goes on, what I don't know, but there are alot of assumptions inherent in the game and a lot of the tech really isn't that magic. Even anti-gravity, we do not know what gravity is, it would be that much of a leap of logic to think once we figure out how it works we would also be able to manipulate it.

 

[Strummist]

One way for Rock to hide might be to spend some time in advance heating up a bunch of asteroids with the ship's laser. During this phase it may be quite visible.

So it's a hot rock amongst many others.

 

[mike wightman]

Some salient facts:

The hull must be impermeable, otherwise the the crew would be cooked, irradiated (which heat is just another form of radiation), etc. . This is solid, there is no way around this fact; otherwise as well we would see focused heat weapons and such.

The fusion plant doesn't generate power by physical work like generating stream for a turbine. So the technological answer is it turns radiant energy into electricity, like with photo-voltaic cells.

The ship can't radiate enough energy as it is (vacuum is a great insulator), so something must be happening. We have heat exchanger technology now, it isn't that much of an assumption that it is far more efficient. Most of the wasted energy today is in heat due to inefficient designs, poor management, etc.; so in the future, they would be looking to recapture that heat and use it for power. Electricity is the easiest to figure in room temperature supercondutors are most likely commonplace, which reduces the heat buildup of resistance; lighting elements and such, probably unknown today, but I doubt it is incandescent. Others it just goes on, what I don't know, but there are alot of assumptions inherent in the game and a lot of the tech really isn't that magic. Even anti-gravity, we do not know what gravity is, it would be that much of a leap of logic to think once we figure out how it works we would also be able to manipulate it.

Please - before discussing facts go and learn some basic physics. There are considerable errors in your pseudo-science.

 

[Dragoner]

You are wrong.