What happens to the "waste" produced by ship's engines?

[Enoki]

Just curious what everyone thinks they'd do with the by products produced from the various drives and power plant on a ship. After all, if you fusion hydrogen you end up with helium as a by product...

Is it collected for eventual sale? Is it just dumped over the "side?" What about in jump space?

 

[atpollard]

Helium is allowed to build up in the ship's atmosphere until everyone has a squeaky voice and then it is purged at the annual maintenance ... making it hard to trick traffic control that you are nowhere near due for annual maintenance.

 

[AnotherDilbert]

At a guess we do not produce enough fusion products to bother with. Just dump it...

Even in jump space a few kg of plasma in nothing to worry about.

 

[pendragonman]

Just curious what everyone thinks they'd do with the by products produced from the various drives and power plant on a ship. After all, if you fusion hydrogen you end up with helium as a by product...

Is it collected for eventual sale? Is it just dumped over the "side?" What about in jump space?

And just where do you think contra grav comes from? o:

 

[Garyius2003]

It goes in the same magic hole as the heat. I play it is some side effect of the grav plates

 

[Timerover51]

A lot depends on how you assume the ship's maneuver drive operates. Does it use a fusion reaction drive or some form of reactionless drive, such as a contragravity drive or a Dean Drive?

If it is a fusion reaction drive, then the helium departs in the reaction mass. If you use a reactionless drive, powered by the ship's power plant, then you have some helium to depose of, which I view as being chilled and then pumped into an empty Liquid Hydrogen tank for venting once back in normal space, or sale once you land.

 

[Carlobrand]

So, if you take a dTon of hydrogen and you fuse it for energy, you end up with a dTon of helium, no? Or maybe a dTon of mixed hydrogen and helium if your reaction wasn't fully efficient. One way or the other, I don't recall any ships having storage space for a dTon of helium waste for each dTon of hydrogen used. You've either got to spend energy cooling it and condensing it to liquid and then rigging your existing tanks to accept the waste while keeping it separate from the rest of the fuel, or you dump it. Seems to me it's probably cheaper to dump it.

 

[kilemall]

So, if you take a dTon of hydrogen and you fuse it for energy, you end up with a dTon of helium, no? Or maybe a dTon of mixed hydrogen and helium if your reaction wasn't fully efficient. One way or the other, I don't recall any ships having storage space for a dTon of helium waste for each dTon of hydrogen used. You've either got to spend energy cooling it and condensing it to liquid and then rigging your existing tanks to accept the waste while keeping it separate from the rest of the fuel, or you dump it. Seems to me it's probably cheaper to dump it.

Which means a careful high tech sensor could go looking for helium dumps with telltale ship generation/dump characteristics, and get at least a bearing and speed when the dump occurred.

 

[aramis]

So, if you take a dTon of hydrogen and you fuse it for energy, you end up with a dTon of helium, no? Or maybe a dTon of mixed hydrogen and helium if your reaction wasn't fully efficient. One way or the other, I don't recall any ships having storage space for a dTon of helium waste for each dTon of hydrogen used. You've either got to spend energy cooling it and condensing it to liquid and then rigging your existing tanks to accept the waste while keeping it separate from the rest of the fuel, or you dump it. Seems to me it's probably cheaper to dump it.

Uhm, no.

The mass...

Typically, ²H+¹H = ²He + n, and the neutron often escapes
¹H+¹H = ²He.

So you wind up with around 99.9998% of your starting mass.

Further, He in liquid form is SG=0.125.
H in liquid form is SG=0.0708
0.0708/0.125= 0.56 times the volume.

So it's not a Td either way, tho' it is awful close mass-wise.

Oh, ands the energy release also sheds some mas

 

[AnotherDilbert]

So, if you take a dTon of hydrogen and you fuse it for energy, you end up with a dTon of helium, no?

Not quite. You conserve mass, not volume.

Assuming you burn deuterium: You start with 1 dT of liquid hydrogen (≈ 1 tonne) with trace amounts (~0,0156%) of deuterium (²H, a rare naturally occurring isotope of hydrogen). You fuse some of the deuterium to helium. You end up with 1 tonne of hydrogen with trace amounts of helium (≈ 1 dT).

Burning all the hydrogen, like in a star, requires vastly higher temperatures and pressure, and vastly less fuel. If you could burn all the hydrogen successfully 1 dT = 1 tonne of hydrogen would become roughly 993 kg helium (and 7 kg energy). 993 kg liquid helium would be 0,993 / 0,125 ≈ 7,94 m³ or 0,57 dT liquid helium. You would have produced 7 kg energy, with E = mc² we can get that this is 7 × 300 000 000² ≈ 6,3 × 10¹⁷ J or about 20 GW for a year. If we could make use of this it would power a small starship for decades.

Edit: I'm too slow, Aramis said the same thing faster...

 

[kilemall]

I could see excess helium being saved as a fire suppression gas.

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20040161188.pdf

ESPECIALLY for misadventure prone people with starships that we may know.

Also possibly a cheap inert safe gas to charge EVA thruster packs with.

 

[Reynard]

I've always assumed those iconic illustrations featuring what look like exhaust ports aft were for dumping all power wastes since a reactionless maneuver drive does not produce a mass to be ejected.

 

[boomslang]

I've always assumed those iconic illustrations featuring what look like exhaust ports aft were for dumping all power wastes since a reactionless maneuver drive does not produce a mass to be ejected.

They were originally intended to be m-drive rocket exhausts, of course, but after switching to a gravitics-based model, I tend to retcon them as p-plant heat sinks.

 

[Carlobrand]

I find that I must apologize for my clearly far too casual imprecision. You end up with 0.999... tons of a hydrogen - helium mix which, if you invested the effort to chill down, would still occupy most of a dTon at best...

...thereby still leaving you with the core problem of whether it was worth the additional equipment and effort for you - and possibly every other arriving ship - to fly in with fuel tanks filled with waste hydrogen and a bit of party balloon stuff. I guess it might be sellable as fuel for fuel cells.

Which means a careful high tech sensor could go looking for helium dumps with telltale ship generation/dump characteristics, and get at least a bearing and speed when the dump occurred.

Ayup. Of course, they could get that info just by looking at you - you do glow rather brightly in infrared - if it weren't for whatever magic is out there keeping your infrared from being seen.

 

[kilemall]

Ayup. Of course, they could get that info just by looking at you - you do glow rather brightly in infrared - if it weren't for whatever magic is out there keeping your infrared from being seen.

It would be for tracking on ships on the drift that are not firing their engines or in IR detect range, or have gravitic drives that otherwise do not leave heat signatures or ion trails.

 

[Carlobrand]

It would be for tracking on ships on the drift that are not firing their engines or in IR detect range, or have gravitic drives that otherwise do not leave heat signatures or ion trails.

I'm sorry, that was actually a joke. I was alluding to one of the more infamous holes in the game's science: even the smallest of ships in this game generate enough energy with their power plant to power a small city, so the ship itself would glow like a sun in even a modern infrared sensor at pretty much any range up to ... I think someone said out as far as Pluto, once. Not sure if that's true or not, but you get the idea.

This game sweeps that bit under the carpet in the interest of having a more interesting combat so, yes, your alternate method of tracking would come to the fore.

 

[whartung]

This game sweeps that bit under the carpet in the interest of having a more interesting combat so, yes, your alternate method of tracking would come to the fore.

Not really. Outside of black globes, there is no "in game" stealth to hide ships. Any of the games that deal with the issue at all present that there is "something" out there, you just don't know what it is, and it's not close enough to get a viable weapons lock on it.

But deep space sensing is mostly a given.

 

[atpollard]

Not really. Outside of black globes, there is no "in game" stealth to hide ships. Any of the games that deal with the issue at all present that there is "something" out there, you just don't know what it is, and it's not close enough to get a viable weapons lock on it.

But deep space sensing is mostly a given.

Except for the LBB rules on Detection and Tracking ... which suggest "I can't see you" beyond 900,000 km.

DETECTION
Ordinary or commercial starships can detect other ships out to a range of about one-half light-second; about 1,500 millimeters*. Military and scout starships have detection ranges out to two light-seconds; 6,000 mm or 6 meters*.
Ships which are maintaining complete silence cannot be detected at distances of greater than half detection range; ships in orbit around a world and also maintaining complete silence cannot be detected at distances greater than one-eighth detection range. Planetary masses and stars will completely conceal a ship from detection.
Tracking: Once a vessel has been detected, it can be tracked by anyone up to three light-seconds (about 9,000 mm, or 9 meters*).

* one millimeter equals 100 kilometers

 

[Carlobrand]

No, not in-game stealth per se, but MT introduced that sensor procedure where you have to roll to detect, and those low tech computers and sensors stand a fair chance of not detecting you even when you're both in the same hex. It might as well be invisibility for the effect it has.

And it's hard to explain agility having any impact at all at ranges under a light second without something going on that makes your precise location fuzzy.

 

[kilemall]

I'm sorry, that was actually a joke. I was alluding to one of the more infamous holes in the game's science: even the smallest of ships in this game generate enough energy with their power plant to power a small city, so the ship itself would glow like a sun in even a modern infrared sensor at pretty much any range up to ... I think someone said out as far as Pluto, once. Not sure if that's true or not, but you get the idea.

This game sweeps that bit under the carpet in the interest of having a more interesting combat so, yes, your alternate method of tracking would come to the fore.

Well of course, one can argue how many AUs X energy output is detectable, etc.etc., but the rules are what they are, for gameplay reasons, and so IMO the thing to do is to assume the technology does indeed somehow dampen/screen/absorb/use all that IR such that the ranges are 'right'.

A time-honored scifi tradition of making the tech fit the story.