CT Only: The Space-Tug

[tim_manley]

One of my most beloved ships from Star Trek was the tug

http://evilgenius180.files.wordpress.com/2009/08/therm04.jpg

Doing this in CT is difficult. For one, a smaller ship can use more fuel than a larger ship if it has more jump.

For example:
The BiggusTimmus Class Tug Mk I
total tonnage 1000T
That gives you:
Jump, Man & Pplant of E = 55dton
Gives J1 with 1G
Fuel requirement
10*Pn (or 10*1=10dton)
0.1 * dton * Jump# = 0.1 * 1,000 * 1 = 100dton

That's only 165dton
You can fill up 35dton with the bridge, computer, and a cabin or three

That gives us 800T in cargo, or x8 100T pods

But, if your tug has no pods it's a 200T ship with E drives
a 200T ship per the rules with an E drive has a J5 and M5 with Powerplant 5

but hang on, let's do the fuel...
10*Pn = 50dton
0.1*dton*J=0.1*200*5=100
for 150 dton of fuel

that's +30dton in gas just because this tug isn't hauling cargo pods

it gets more complication when you have 1 pod, vs 2, vs 3, vs 4, etc.

... So, am I smoking something or is my math right? This 1,000dton tug when it drops it's pods and is a svelt 200dton ship doesn't have enough gas to keep the powerplant running....

 

[mike wightman]

The fuel formula for power plants in CT is broken.

Fuel = 0.05 x hull tonnage x power plant number gives more consistent results.

If you want to lower power plant fuel then a factor of 0.01 can be used instead of the 0.05 (this is what HG uses).

Still not ideal but better than the flat 10t per power plant number.

This is something that should have been fixed with the "81 revision of CT.

 

[The Oz]

I use an even simpler formula for CT power plant fuel:

10 tons fuel per power plant letter

Plant A needs 10 tons
Plant B needs 20 tons
Plant C needs 30 tons
and so on....

It changes some of the standard designs a bit, but that's OK with me. YMMV.

 

[martletsquire]

I like the EP equals fuel usage formula. Makes sense, and since you have to figure out the power plant output anyways...

 

[aramis]

I like the EP equals fuel usage formula. Makes sense, and since you have to figure out the power plant output anyways...

I, as well, like it. But I realize that the 250MW equivalence means 0.01% or so return on fusion potential.

 

[martletsquire]

Well, you do have to contain the magnetic bottle or your pretty little starship will be renamed... NOVA!

And yes, the output is rather low. I always put it up to the inefficiencies of a plant made by Imperial Ford for the masses to use, rather than a totally custom design run by a bunch of egg-heads. Or to simple game mechanics and such.

No one wants their private pile to go bad, and I can't even imagine how you would SCRAM a fusion plant.

 

[tim_manley]

I use an even simpler formula for CT power plant fuel:

10 tons fuel per power plant letter

Plant A needs 10 tons
Plant B needs 20 tons
Plant C needs 30 tons
and so on....

It changes some of the standard designs a bit, but that's OK with me. YMMV.

That'll fit in CT, and it makes sense. And you can "fudge" with the standard ships and not worry about it.

But, honestly, the only place this can come up with as a problem is if your ship changes it's size, which alters it's specs, like the tug example.

 

[aramis]

That'll fit in CT, and it makes sense. And you can "fudge" with the standard ships and not worry about it.

But, honestly, the only place this can come up with as a problem is if your ship changes it's size, which alters it's specs, like the tug example.

Mongoose uses 2 per drive letter, which is a better fit with CT.

 

[martletsquire]

I also like the Mongoose rules for Commercial Units, as I always thought that CT usage was way too much. Forgot about them because I've recently been reworking all my ship files that I have collected over the years and have been concentrating on military vessels.

IMTU, I do one of two things:

Mongoose Traveller for Commercial Units and for bridge sizes up to 300t, along with all the neato new ship stuff you can add...(grabber arms and such)

Use High Guard EP rules for custom plants.

I like the idea of using commercial model engines in many military vessels, as I like the modularity (IMTU, most small components are swappable on any plant of the same type. Standardized bolts and nuts, zy thingies and such. Cuts down on maintenance depot needs and such.)

 

[Zutroi]

Well, you do have to contain the magnetic bottle or your pretty little starship will be renamed... NOVA!

And yes, the output is rather low. I always put it up to the inefficiencies of a plant made by Imperial Ford for the masses to use, rather than a totally custom design run by a bunch of egg-heads. Or to simple game mechanics and such.

No one wants their private pile to go bad, and I can't even imagine how you would SCRAM a fusion plant.

Fusion should be incredibly easy to 'scram'... Just vent some of the plasma overboard.

 

[martletsquire]

Vent... Burning solar heat level hot plasma... as your magnetic bottle is failing... hahahahahahahahaaaaaa (plunk)

More likely have to eject the whole bottle out of the ship before it goes critical, kinda like in the Weber Herrington books.

Even that has its inherent problems, like opening a hole in your ship to get rid of a fusion bomb, and then eject a fusion bomb right next to your now compromised hull structure, and then having said fusion bomb go..BOOOM.

On the other hand, if your bulkheads are strong enough, I wonder what g accelerations you'll get from the Orion effect..

Oh, so many ways for Murphy's little FUBAR demons to affect the effect, so to speak.

hehehehe.... Big-bada-boom... hahahaha

This is actually a really good question. How do you scram your plant before it blows?

 

[aramis]

Fusion drive cracks? it simply vents, cooks anyone within a couple meters ruins the drive dials, and done. There's probably less than 0.1L per Td of drive in the fusion bottle.

Fusion requires heat and pressure - if it doesn't have both, it simply stops. The Fusion Bombs don't cook for minutes - they cook for seconds. The "fireball" is simply the superheated air moving normally - but it's done as soon as the flash is over. A drive cook-off won't even be that much. Just a flash, maybe a "Boom" from the drive bay overpressuring from thermal expansion.

Ok, Hydrogen is 14x the specific heat of air and 1/15th the density at STP... and sure, it's 100,000,000° K+... so that 0.1L will flash heat 1 KL to 10,000° K. And it's probably having to heat about 7 kL of air, so it's only 1,500° K. Oh, and odds are good there's as much tonnage of other drives in the same bay, so only about 750° K. In other words, about the same range as a housefire.

 

[Carlobrand]

I'd worry more about coolant.

There's some system for taking the energy of the reaction and turning it into something useful for the ship. If it operates like a solar panel - some sort of Sci Fi direct conversion of the gamma to electricity, maybe - then your power just stops when the reaction stops. However, if it operates like our steam generators - expansion of a working fluid to mechanically drive a generator - then, depending on the amount of fluid involved, you could have several seconds or minutes of accumulated energy in the working fluid. If that working fluid escaped from the system meant to contain it, it could deliver a lot of energy to someplace that energy was not intended to be - like the engine control room you happen to be standing in. Or, the fluid itself could have dangerous properties: some of our subs were using sodium as a coolant.

 

[robject]

Mongoose uses 2 per drive letter, which is a better fit with CT.

That was one of my considerations at the time.

But now my memory fails me: was that for 2 weeks' operations?

 

[aramis]

That was one of my considerations at the time.

But now my memory fails me: was that for 2 weeks' operations?

Might be. I'd have to check. Checking. Yep, per 2 weeks. So, 1Td per drive letter per week.

 

[Zutroi]

My thinking is in line with Aramis'. Fusion requires a LOT of work to start up and maintain! Your 'stellar core temperature' plasma is probably well under a kilogram of material (the rest, IMTU, is cooling mass and working fluid for an MHD), so you don't really have much actual heat there... Dump it to space, and it'll expand and cool quite effectively.

A scram could also be done via a purge of a large volume of Xenon, which is high enough up the periodic table to not work as a fusion fuel under any conditions...

 

[Carlobrand]

My thinking is in line with Aramis'. Fusion requires a LOT of work to start up and maintain! Your 'stellar core temperature' plasma is probably well under a kilogram of material (the rest, IMTU, is cooling mass and working fluid for an MHD), ...

I like that, preheats the hydrogen and gets some work out of it. I don't know enough physics to know if it works well. I recall one reason the Navy went to sodium-cooled reactors was that sodium had a high heat capacity.
Mostly greek to me, but I know your hydrogen would be changing from a supercooled liquid state to a high-temperature gas, probably under very high pressure. Comes back to the coolant possibly being more dangerous than the reactor - a coolant leak either means something at supercooled temperatures or something at extremely high temperature and pressure.

There's something like 2.4 million seconds in a 28-day month, so near as I can figure we're consuming hydrogen fuel at a rate measured in grams per second. Very, very hot, but not a lot of it - enough to make a royal mess of the core if it weren't contained, but I don't think enough to get out of the power plant. One CT EP brings a ton of iron to melting, but a ton of iron is only a block 50 cm on a side - assuming I got the math right.