Could you stand living in a scout ship?

[Timerover51]

Can you give a rationalle for that assumption? At this point we are just beginning to see a break-even point for fusion power. How would we know how much fuel a power plant would need 'in reality?'

The following comments are based on information from this website at the University of Pennsylvania:

http://www.sas.upenn.edu/~kennethp/nuclearenergy.pdf

The complete fission of one pound of U-235 results in an energy equivalent to one million gallons of gasoline. One pound of gasoline is rated at about 18,000 BTUs of energy, and one kilowatt is equal to 3412 BTU. So, figure a pound of gasoline is good for 5 kilowatts of power. A gallon of gasoline weighs 6 pounds, so a gallon of gasoline will yield 30 kilowatts of power if burned with 100% efficiency. Therefore, the fission of one pound of U-235, at 100% efficiency, will yield 30 million kilowatts of power, or 3424 kilowatts per hour, assuming a 24 hour and 365 day years. Currently, assuming a high-efficiency reactor, you might get about 25% or so efficiency at energy conversion, so figure that you would need to burn 4 pounds or so of U-235 per year to get that power.

The following website gives some fusion reaction yields and compares fusion and fission.

http://hyperphysics.phy-astr.gsu.edu/Hbase/nucene/fusion.html

The Deuterium-Tritium fusion reaction is rated at an energy yield of 17.6 MeV per fusion, while U-235 is rated at 215 MeV per fission. However, on an equal weight basis, as there are a lot more fusion reactions per weight, the fusion reaction produces 3.84 times the power by weight of reactants. So one pound of equal parts Deuterium and Tritium completely reacted will yield, at a little more than 25% efficiency, the same amount of power as 4 pounds of U-235.

However, the Tritium in the above reaction is not really found naturally, and would have to be produced in some manner. The Deuterium-Deuterium fusion reaction has two possible outcomes, one yielding 3.27 MeV and one 4.03 MeV per fusion. They average out to 7.3 MeV for every 2 fusion reactions of a pair of Deuterium atoms. That is quite a bit less energy from about 8 Atomic Mass Units, compared to 5 AMU of the Deuterium-Tritium reaction, but Deuterium is a naturally occurring stable isotope of Hydrogen, and simply has to be separated out. Dividing U-235 mass by 8, you get 29.375. Multiplying by the average energy yield of the fusion of 4 Deuterium atoms of 7.3 MeV, you get 214.4 MeV for the same weight of Deuterium as one atom of U-235. Therefore, for every pound of Deuterium completely reacted in fusion, you get just about the same energy as a pound of U-235.

Now, to avoid one horrendous heat exchange problem, the fusion plants in Traveller have to be fantastically efficient at converting fusion energy to electricity, so one pound of Deuterium per year would give about 3400 kilowatts of power for every hour of a year. One kilogram of Deuterium will give, at 2.0246 pounds per kilogram, 7,495 kilowatts of power per hour for an entire year. I suspect that much power would be more than adequate for the basic power needs of a starship in Traveller, unless it is a REALLY, REALLY BIG ONE. For your average Scout Ship, or say a cargo/passenger ship of under 1000 tons or so, that should be far more than needed.

Now, you could require 6.5 tons of Liquid Hydrogen per year for a ship, as Deuterium exists in the ratio of 1 Deuterium atom per 6,420 hydrogen atoms, so 6,420 kilograms of Hydrogen will contain 1 kilogram of Deuterium for my Deuterium to Deuterium fusion reactor. That is if you want to extract the Deuterium onboard. Otherwise, a ton of Liquid Dee should prove more than enough for a year or so for my power plant.

Mental note to Poster: Based on the above fission yields, give serious thought to small fission plants for long-endurance vehicles. Maybe HBP direct conversion of nuclear to electricity units? Need to ponder.

Edit Note 2: The Effects of Nuclear Weapons, 1977 edition, gives the yield of 2 ounces of completely fissioned U-235 as 1.16 Million Kilowatt hours, so I will need to adjust the above figures by a factor of 3. Therefore a pound of U-235 will yield 9.28 Million Kilowatt hours, rather than 30 Million Kilowatt hours. Will correct on Jan. 31, 2015. This does not significantly change the result.

 

[aramis]

Yes correct. When Fusion is up and functioning as a viable power source, it will be at the least as efficient as Fission, and probably more efficient.

Not of need a given. Sociopolitical issues, as well as environmental ones, will make it relatively popular in relation to fission the moment it becomes viable in the ≤$1/kWH of output range... even if it's got an (in)efficiency of 1kL/H/kW.

 

[WistfulD]

The following... ...if burned with 100% efficiency... ...you might get about 25% or so efficiency at energy conversion... ...Now, to avoid one horrendous heat exchange problem, the fusion plants in Traveller have to be fantastically efficient at converting fusion energy to electricity...

{quote reduced to relevant points} That efficiency is the point I am making. Modern tokamak reactors have decent intrinsic efficiency, once you exclude the energy required to power the magnetic field which holds the fusing hydrogen. Because of the that power requirement, the net efficiency of that form of fusion is below zero. Other methods are now being explored, and may be headed towards the next breakthrough. However, that means that the net power available from a fusion power plant could be anywhere from just above breaking even (why would they have it on commercial ships if it didn't?), to that theoretical limit you just highlighted. Traveller's plants could be anywhere on that line. Whulorigan's social explanation (which I'm reducing in my mind to "if it weren't more efficient than fission, they would instead use fission") is a reasonable justification, although I agree with your caveat, Aramis.

Now, you could require 6.5 tons of Liquid Hydrogen per year for a ship, as Deuterium exists in the ratio of 1 Deuterium atom per 6,420 hydrogen atoms, so 6,420 kilograms of Hydrogen will contain 1 kilogram of Deuterium for my Deuterium to Deuterium fusion reactor. That is if you want to extract the Deuterium onboard.

I'd always assumed centirfuging for Deuterium and Tritium (along with filtering out ammonia or whatnot) was what fuel processors did, and that refined fuel you purchased was pure Deuterium (or deuterium/tritium, He3, etc.).

Mental note to Poster: Based on the above fission yields, give serious thought to small fission plants for long-endurance vehicles. Maybe HBP direct conversion of nuclear to electricity units? Need to ponder.

Real world endurance vehicles use Betavoltaic atomic batteries using rare earth element radioisotopes such as promethium-147 and technetium-99. The semiconductor p-n junction-derived direct conversion is extremely durable to maintenance-free performance. To compete on that level, a micro-chain reaction fusion plant would have to drastically increase the output without increasing the risk of breaking down.

 

[atpollard]

{quote reduced to relevant points} That efficiency is the point I am making. Modern tokamak reactors have decent intrinsic efficiency, once you exclude the energy required to power the magnetic field which holds the fusing hydrogen. Because of the that power requirement, the net efficiency of that form of fusion is below zero. Other methods are now being explored, and may be headed towards the next breakthrough. However, that means that the net power available from a fusion power plant could be anywhere from just above breaking even (why would they have it on commercial ships if it didn't?), to that theoretical limit you just highlighted. Traveller's plants could be anywhere on that line. Whulorigan's social explanation (which I'm reducing in my mind to "if it weren't more efficient than fission, they would instead use fission") is a reasonable justification, although I agree with your caveat, Aramis.

Since the 'inefficiency' eventually ends up as waste heat, either the ships have very efficient fusion power plants (and little waste heat) or inefficient fusion power plants and some 'magic heat sink'* that lets the ship dispose of the vast amounts of waste heat.

*The alternative is that the waste heat builds up until the whole ship is hotter than a sun and melts.


IMO, like so many things in science fiction (and especially space opera), it becomes a personal choice of where you want to place your 'magic black box'.

 

[aramis]

WistfulD:

You cannot exclude the operating costs of the reactor itself. Net efficiency is all that matters in the end.

Tokomaks are extremely inefficient at producing fusion. At present, it's looking like primarily an energy recapture issue - we know how much energy is released, but cannot convert it to useful energy sufficient to run the tokomak. The newer designs (now buried behind military secrecy) had lower operational costs in energy... but are still highly inefficient as a source of useable energy.

The only reason they're even potentially useful is that the energy release is so high that the tiny fraction not used for maintenance of the reaction promises plentiful fuel and no toxic waste.

 

[Blue Ghost]

A Scout Ship, by definition, is 100 Traveller dTons. Allowing 13.5 cubic meters per dTon, this would equate to a wet navy ship of 1350 metric tons displacement, or 1328 tons standard displacement (standard displacement uses the UK Long Ton of 2240 pounds).

The U-505 submarine, preserved at the Museum of Science and Industry in Chicago, displaces 1,100 long tons surfaced and 1,232 long tons submerged. It is smaller in terms of volume than a standard Traveller Scout Ship. The U-505 had a crew of between 48-56 men, and a patrol endurance on the order of 90 days. I have been in the U-505 several times, and it is very tight quarters.

I have also been onboard the USS Silversides, SS-236, presently a museum ship in Muskegon, Michigan. I even have slept in the captain's bunk. That is larger than the U-505, with a submerged displacement of 2,424 tons, so a bit larger than a Scout Ship. While the pre-war crew was set at 60, considerably more were carried in wartime. Patrol endurance was set at 75 days, mainly limited by food and fuel. Again, quarters are very tight, with the captain's quarters being large enough to hold a bunk, small desk, and wash basin. I would put them at less than one-fourth the size of a Traveller stateroom in terms of deck area, with a lot less headroom. The sub's crew quarters stack bunks 3 high, and the wardroom for the officers is about half the size of a standard Traveller stateroom, again with less headroom.

I fail to see any problems with putting 4 persons for all of one week in a Traveller Scout Ship.

I think the difference there is that a scout ship has approximately the interior space of a luxury home, while the rest of its space is dedicated to fuel storage and engines.

 

[atpollard]

I think the difference there is that a scout ship has approximately the interior space of a luxury home, while the rest of its space is dedicated to fuel storage and engines.

The actual 'living space' is even smaller than that ... 4 staterooms = 16 dTons = 800 sf of living area = efficiency apartment ... with 4 people locked in for 1 week.

 

[salochin999]

Since the 'inefficiency' eventually ends up as waste heat, either the ships have very efficient fusion power plants (and little waste heat) or inefficient fusion power plants and some 'magic heat sink'* that lets the ship dispose of the vast amounts of waste heat.

*The alternative is that the waste heat builds up until the whole ship is hotter than a sun and melts.


IMO, like so many things in science fiction (and especially space opera), it becomes a personal choice of where you want to place your 'magic black box'.

and some 'magic heat sink'

steam powered space ships ftw

 

[Spinward Scout]

The actual 'living space' is even smaller than that ... 4 staterooms = 16 dTons = 800 sf of living area = efficiency apartment ... with 4 people locked in for 1 week.

I would assume in the Far Future, the staterooms could use sliding walls, something like this:

Gary Chang's Domestic Transformer

For those that don't want to click, a guy in Hong Kong used sliding walls to turn a tiny apartment into 24 different rooms. That might not work for double occupancy, tho.

Here's another:

 

[Timerover51]

I'd always assumed centirfuging for Deuterium and Tritium (along with filtering out ammonia or whatnot) was what fuel processors did, and that refined fuel you purchased was pure Deuterium (or deuterium/tritium, He3, etc.).

Tritium is an isotope of Hydrogen that essentially does not EXIST in nature, having a half-life of 12.3 years. Helium-3, being a gas, is not going to be present in water. For every kilogram of Deuterium produced from Hydrogen, you have to process 6420 kilograms of Hydrogen, at least using Earth's isotope ratio. That is not what your fuel processors are doing, they are simply recovering Liquid Hydrogen. As for centrifuging, would you care to consider how long or how large a bank of centrifuges it would take to separate out ONE kilogram of Deuterium with near 100% efficiency?

Real world endurance vehicles use Betavoltaic atomic batteries using rare earth element radioisotopes such as promethium-147 and technetium-99. The semiconductor p-n junction-derived direct conversion is extremely durable to maintenance-free performance. To compete on that level, a micro-chain reaction fusion plant would have to drastically increase the output without increasing the risk of breaking down.

The following quote comes from Wikipedia, so I will not vouch for its accuracy. However, you might want to do the math and figure out how much of the radioisotopes you mentioned would be required to generate at least a 1,000 Kilowatts of power, verses a few microwatts. You might want to figure out how large the resultant battery would be, and also as the radioisotopes have to be artificially produced how much they would cost. The only current source of Technetium-99 is the reprocessing of nuclear reactor fission waste. Does that tell you something about the cost? That is also the primary source of Promethium-147. Neither Technetium or Promethium exists as a naturally occurring element.

This is from Wikipedia. I will not vouch for its accuracy.
Betavoltaic power sources (and the related technology of alphavoltaic power sources[2]) are particularly well-suited to low-power electrical applications where long life of the energy source is needed, such as implantable medical devices or military and space applications.

I repeat, you are not powering a heart pacemaker. You are powering a grab-carrier or a tracked or wheeled All-Terrain-Vehicle requiring about 1,000 or more horsepower for propulsion and, in the case of the grav vehicle, lift. Power plants are going to need to deliver on the order to 1,000 Kilowatts or more.

 

[Timerover51]

Dumb question number 1. Where did the figure of 4 persons occupying a Scout Ship come from? Or is this a modified ship of a Retired Scout.

Dumb question number 2. Why is this an issue of whether or not your Character, not you as a real person playing the Character, can stand being on a Scout Ship, or a Free Trader, or a densely inhabited asteroid, or a 600 Ton Liner? Your character has his/her/its own individual stateroom to retire too.

Have any of you as posters seen the pictures of the living conditions on World War 2 troopships, with the bunks stacked 3 high, and just enough room between bunks to walk? They were carrying 15,000 men per trip on the Queen Mary and Queen Elizabeth during the troop build-up in England prior to the Normandy invasion, and those trips ran 5 days. The men were hot-bunked. They survived.

Guys onboard of a World War 2 US sub had the main crew berthing compartment between the maneuvering room and the forward Diesel Generator room. Bunks were 3 high. I know, I slept in one onboard on the USS Cobia in Manitowoc, Wisconsin, as well as touring the boat with a several troops of Boy Scouts. Your space was the bunk with a drawn curtain. I would highly suggest if you are near a submarine museum to tour the boat and see the living conditions. No private toilet facilities by the way. Then consider that just about all of the men onboard had never been on a ship or to sea before. They survived 60 to 90 day combat patrols.

What is the problem with surviving onboard of a Scout Ship?

 

[mike wightman]

The standard scout/courier has four staterooms so can carry four people.

Crew, military personnel, PCs, really hard up NPCs may opt for double occupancy so increasing the number to eight, but four would be the usual maximum.

As to your final question I can not see any problem at all - people live in much greater density in much worse conditions.

 

[McPerth]

The actual 'living space' is even smaller than that ... 4 staterooms = 16 dTons = 800 sf of living area = efficiency apartment ... with 4 people locked in for 1 week.

Well, 800 sf it's about 85-90 m³, right?

As I already said, few 4 member families in Barcelona live in larger apartments.

And don't forget that the scout has a large bridge (20 dtons, so about 1.25 times the living space. Why a ship assumed to be crewed by a single person, two at most, has such large a bridge escapes me). Even if a good part of it it's equipement, even in only 20% of it is space where you can walk it can be used as additional living space (mostly in jump, where the bridge has to be used less).

Dumb question number 1. Where did the figure of 4 persons occupying a Scout Ship come from? Or is this a modified ship of a Retired Scout.

I guess from the fact it has 4 stateromms, so being able to "comfortabily" carry 4 persons without recurring to double occupancy.

 

[rancke]

And don't forget that the scout has a large bridge (20 dtons, so about 1.25 times the living space.

Except it doesn't. The Scout/Courier in Traders and Gunboats has a five square (2.5 T) bridge and a four square avionics section for a total of 4.5 T.

(On the other hand, the living quarters take up 25T rather than 16; the staterooms are six squares (3T) each).

One of the problems I have with the rigid 20T bridge under the RAW is that it's not actually realized on a lot of the early deckplans. The other problem is that in the real world, problems with space constraints are handled by compromising on something. If I need to put 102T of components into a 100T design, I want the option to put in an 18T bridge, at whatever effect on price, comfort, and safety that I'm prepared to live with. The 20T bridge of the ship design system (and many other features) is a wargames rule, not an RPG rule.

BTW, don't the new T5 makers allow tweaking design parameters, enabling ship designs with smaller (but more expensive) components?


Hans

 

[McPerth]

Except it doesn't. The Scout/Courier in Traders and Gunboats has a five square (2.5 T) bridge and a four square avionics section for a total of 4.5 T.

(On the other hand, the living quarters take up 25T rather than 16; the staterooms are six squares (3T) each).

It seems that they took some bridge area for living space, then :CoW:

One of the problems I have with the rigid 20T bridge under the RAW is that it's not actually realized on a lot of the early deckplans. The other problem is that in the real world, problems with space constraints are handled by compromising on something. If I need to put 102T of components into a 100T design, I want the option to put in an 18T bridge, at whatever effect on price, comfort, and safety that I'm prepared to live with. The 20T bridge of the ship design system (and many other features) is a wargames rule, not an RPG rule.

BTW, don't the new T5 makers allow tweaking design parameters, enabling ship designs with smaller (but more expensive) components?

I don't know about T5, but other versions already changed it:

• MT has not bridge as such, but you need space for controls and computers (see that in CT you need for both, bridge and computer)
• IIRC TNE and T4 had workstations as the required space for controling the ship, instead a bridge as such, but I'm not too familiar with neither of them nor have I ever tried to design ships under their systems.
• MgT has smaller bridges for smaller ships

 

[aramis]

Well, 800 sf it's about 85-90 m³, right?

Depends upon ceiling height. Typical housing ceilings run 7'6" to 10', nominally 8'. 6400cf is right about 200m³

 

[McPerth]

Depends upon ceiling height. Typical housing ceilings run 7'6" to 10', nominally 8'. 6400cf is right about 200m³

sf does not mean square feet? I guessed Artpollard has already accounted for the ceiling heigh and told about the surface in quare feet...

 

[Spinward Scout]

What is the problem with surviving onboard of a Scout Ship?

Well, if you're on a ship crossing the Atlantic, you can open up a hatch and get a breath of fresh air. And even submarines have snorkles to bring in fresh air. Anyone on a Detached Duty Scout/Courier can't do that. It's not that it isn't survivable. It can be monotonous and claustrophobic for some. The person on the bridge at least has a nice view.

 

[salochin999]

Dumb question number 1. Where did the figure of 4 persons occupying a Scout Ship come from? Or is this a modified ship of a Retired Scout.

Dumb question number 2. Why is this an issue of whether or not your Character, not you as a real person playing the Character, can stand being on a Scout Ship, or a Free Trader, or a densely inhabited asteroid, or a 600 Ton Liner? Your character has his/her/its own individual stateroom to retire too.

Have any of you as posters seen the pictures of the living conditions on World War 2 troopships, with the bunks stacked 3 high, and just enough room between bunks to walk? They were carrying 15,000 men per trip on the Queen Mary and Queen Elizabeth during the troop build-up in England prior to the Normandy invasion, and those trips ran 5 days. The men were hot-bunked. They survived.

Guys onboard of a World War 2 US sub had the main crew berthing compartment between the maneuvering room and the forward Diesel Generator room. Bunks were 3 high. I know, I slept in one onboard on the USS Cobia in Manitowoc, Wisconsin, as well as touring the boat with a several troops of Boy Scouts. Your space was the bunk with a drawn curtain. I would highly suggest if you are near a submarine museum to tour the boat and see the living conditions. No private toilet facilities by the way. Then consider that just about all of the men onboard had never been on a ship or to sea before. They survived 60 to 90 day combat patrols.

What is the problem with surviving onboard of a Scout Ship?

I don't think there's a critical problem at all for the sort of reasons you mention especially if it's only a week at a time but talking about it can generate ideas as to how it could be made more comfortable.

From this thread so far I'm going to use:

1) sliding interior walls to make 4 x small state rooms or 2 x okay ones or 1 x big one
2) 'live' walls i.e. you can program them to display whatever you want like a more advanced version of PC wallpaper e.g. beach scenes, forest scenes, cool nebulas etc whatever you like
3) sounds also - music, wave noises whatever

#

on the minimum 20T bridge thing I've always treated it as bridge + all the electronics scattered around the ship.

 

[WistfulD]

Tritium is an isotope of Hydrogen that essentially does not EXIST in nature, having a half-life of 12.3 years. Helium-3, being a gas, is not going to be present in water.

When did we mention water? How is it relevant?

For every kilogram of Deuterium produced from Hydrogen, you have to process 6420 kilograms of Hydrogen, at least using Earth's isotope ratio. That is not what your fuel processors are doing, they are simply recovering Liquid Hydrogen. As for centrifuging, would you care to consider how long or how large a bank of centrifuges it would take to separate out ONE kilogram of Deuterium with near 100% efficiency?

No I would not. I assumed like everything else that it was sci-fi hand-waved away. Do you know enough about the fusion process to tell us whether separating out the deuterium is required?

The following quote comes from Wikipedia, so I will not vouch for its accuracy. However, you might want to do the math and figure out how much of the radioisotopes you mentioned would be required to generate at least a 1,000 Kilowatts of power, verses a few microwatts. You might want to figure out how large the resultant battery would be, and also as the radioisotopes have to be artificially produced how much they would cost. The only current source of Technetium-99 is the reprocessing of nuclear reactor fission waste. Does that tell you s'omething about the cost? That is also the primary source of Promethium-147. Neither Technetium or Promethium exists as a naturally occurring element.

Why would I care about generating over 1000 Kw? You are putting some odd arbitrary constraints on this thought experiment.

I repeat, you are not powering a heart pacemaker. You are powering a grab-carrier or a tracked or wheeled All-Terrain-Vehicle requiring about 1,000 or more horsepower for propulsion and, in the case of the grav vehicle, lift. Power plants are going to need to deliver on the order to 1,000 Kilowatts or more.

No, you are powering a grab carrier. I am powering a deep space probe, which is how I took the term "long-endurance vehicles." An atv or grab carrier can get routine maintenance, so it doesn't need the lack of mechanical points that a HBP direct conversion of nuclear to electricity would entail, so I am at a lack of understanding why that would be important. What was that part for then?