Ship Operation Costs

[Commander Drax]

"Are they really rust buckets at 40yrs. I have refitted ships every 40 yrs...life expectancy is based on wear and tear numbers. Hence, the nicer the ships life, the lower the maintenance.

While at it most of a ships wear is from re-entry. Ships in the J1 routes could be stopping at highports or stations...etc."

No, not really, its just an expression, though as in all things the quality of the ship would be directly correlated to the amount of quality maintenance that it had recieved over its life time. IMTU some are badly in need of maintainance and repair at 20 years, whilst others are still prestine after a 100 years. As in the real world its all down to the maintainance and loving care or lack off given by owners.

As for re-entry, whilst stressful this wouldnt really be wearing for a traveller starship, as you only get heat build up on the hull when the hull is moving faster than the surrounding air. I assume that most ships break heavily before atmospheric insertion, in which case heat build up is minimised. The only reason why the space shuttle fails to do this is because it does not have the fuel on board sufficient for such heavy braking. But a traveller ship or small craft with that big grav drive.... Hell, even Heplar powered ships should have no problem on re-entry provided they have enough fuel on board to sufficiently slow them...


Savage

 

[Commander Drax]

I see a subsidy as a government contract in which they pay you cash to provide service to a number of key worlds on the route in which it is hoped that further economic development will stimulate trade and improve the economies of the said worlds, hence subsidised merchants wouldnt really be seen in the core worlds were trade is bustling, so its out to the frontier for my subbies....

 

[Commander Drax]

Sorry guys, first two paragraphs of my first post (above) should have been in quotes, for some reason they didnt come out right....

Many Apologies

 

[Drakon]

I ain't so sure about the heat buildup. In another posting someone mentioned that submarine hulls are under far more stress than starships. If you look at likely pressures encountered by each, he may have a point. (I still an not totally convinced, I can see diving a gas giant as potentially putting more pressure on the hull than a sub would feel.)

But heat is another issue. A sub is surrounded by water, and that water is in a pretty narrow band, temperature wise. Between 29 and about 70 degrees F (Yes, I know 29 is less than 32, but salt water is funny that way) Whereas a starship hull frequently goes from almost absolute zero, to room temperature, or what ever the out door temperature is on the planet. And possibly, depending on re-entry speeds and such, far higher.

So maybe a sub has less of a pressure stress, but a starship has a far higher heat stress cycle going on. Its the cycling of the hull that really ruins the ship. How it cycles is less importance.

 

[Drakon]

Originally posted by Commander Drax:
I see a subsidy as a government contract in which they pay you cash to provide service to a number of key worlds on the route in which it is hoped that further economic development will stimulate trade and improve the economies of the said worlds, hence subsidised merchants wouldnt really be seen in the core worlds were trade is bustling, so its out to the frontier for my subbies....

That is the way I see it too. While the government may be able and willing to wait awhile before the route becomes profitable, the freighters themselves can't. Crew wanna eat and get cranky when they don't get paid. Whether the route is profitable for the ship or not, is beside the point. They want paid, NOW.

Just like the guys in the yard that did the refit, the fuel guys, the folks collecting docking fees, etc.

 

[robject]

A word about rust-buckets and ship maintenance: according to CT, the most well-maintained, high-quality TL15 starships won't last 100 years without replacing most of the major systems. Therefore, yearly overhaul is critical.

On the other hand, TL16 vessels, such as vintage Darrian merchant and naval starships, last 1000 years with only tune-ups. Now that's quality.

 

[Commander Drax]

Drakon posted:

I ain't so sure about the heat buildup. In another posting someone mentioned that submarine hulls are under far more stress than starships. If you look at likely pressures encountered by each, he may have a point. (I still an not totally convinced, I can see diving a gas giant as potentially putting more pressure on the hull than a sub would feel.) Whilst I can understand your point about gas giant skimming, I would have thought that the stress encountered by a ship's hull would only be slightly more than that encountered by a high performance air-craft some of which heat up to the point where they physically expand in size slightly whilst flying. Also I would have though that gas giant skimming whilst quick would probably not involve too much friction, after all you wouldn't want to ignite the gasses that your trying to get into your scoops and ultimately your fuel tanks.

 

[Straybow]

All supersonic craft have skin heating problems, typically reaching about 500-600°F. Disembarking crew and ground handlers have to be careful not to touch outer surfaces until they cool.

Thermal heating in space due to direct sunlight can be higher than that (can't seem to find any figures for the shuttle), and re-entry can heat the shuttle tiles to 2200°F iirc. However, the material doesn't dissipate heat quickly. They have demonstrations where they take a block of material, heat it to glowing with a gas flame, then pick it up with bare hands. I imagine Traveller starship hull materials will have astounding thermal properties.

Unless you scoop from exotic atmospheres the chemical environment is benign compared to salt water. So while your TL15 machinery (including airlocks and the like) won't last much more than a century the hull should be good for much longer than that with minimal maintenance.

One problem I have with Traveller maintenance and operation costs is that Traveller ships don't have enough crew to perform maintenance. The 4dT/cabin is luxury passage density aboard a "real" ship. The crew (and steerage passengers) are packed in at 20 times that density. Nobody puts extra crew on a ship just for kicks, they are needed.

But why belabor points already discussed in Traveller Cargo Standards, Making a Jump 2 freighter profitable, Price-Fixed Travel, Far Trader cargo/Freight manifest questions

PS: It works better if you actually put the quoted material between the [ QUOTE ] and [ /QUOTE ]

 

[Commander Drax]

PS: It works better if you actually put the quoted material between the [ QUOTE ] and [ /QUOTE ]

Hey thanks for that!

Points noted, my understanding of gas-giant skimming is that ships dont actually get too deep into atmo, as the gas giants 'surface' and hence diameter is measured from the point that its gasses reach 1 standard atmosphere. Hence it would be possible to skim gases at higher altitudes than this without significant heat build up from friction, even at high speed.

Once again many thanks

 

[robject]

That works for me, and seems to be realistic. 30 years ago, the Classic take on skimming was that ships dove 'deep into the atmosphere', whatever that means.

 

[savage]

Yes CT Canon is clear that TL15 is 40yrs...and then TL16 is a miracle a thousand years.

Instead, IMTU I start out early starships at 40yr lifespan and work up to two hundred and fifty years at TL15 with serious refits. Besides annual maintenance, I insist on a refit every 40 yrs. Even 1000yr TL16 ships, built with a clear understanding of space tech, still requires maintenance and occassional system refits. TL17 appears to be where refits
and external materials dramatically change.

On another note, Starships, space craft, space stations have a lot of wear from their environments. With or without gravitics.
Landing, skimming (all skimming) and a normal beating from debris in orbit impacts the vessel. In earth orbit a screw, screw driver becomes a 17000mph weapon. There is even a nice white paper on Traveller Armour being inadequate. Its a dangerous place.
Now lets move into temperature issues. We have exteme cold and extensive radiation outside the vessel, inside an effort for human conditions and an extemely hot fusion reactor. So its necessary to manage the impact on the materials. Now lets take the vessel and launch it into jumpspace.
This is lot tougher than maintaining a submarine.

Savage

 

[robject]

I have basically the same opinion. A TL15 ship will break down over the decades, and requires knowledgeable staff with the proper parts to keep it running. A TL16 ship is much more maintainable, and much more durable, but still needs tune-ups.

As for the drive, I'll leave that to physicists and those who know enough about it to be worried. Here's the article I always come back to for Traveller fusion:

http://traveller.mu.org/house/fusion.html

This article mentions "hull radiator strips" to conduct heat away from the ship. I'm content just to wave my hands and talk about high-tech thermal coils which are dumping grounds for excess heat, which are changed out either when the ship has its yearly overhaul, or as part of the "life support" maintenance that seems to be too expensive.

 

[savage]

Its a big catch 22. I've read a lot about this and that's an informative article. Problem could become heat tracking. Otherwise, heat seeking missiles and sensor become a threat.

On another note, I refer to the 40 yr refit as mandatory because one element is gutting the core.

Savage

 

[Commander Drax]

Yes, a very interesting article, the basics of which I have more or less gleaned from other sources. My explanation for CT and T20 ships, is that a great deal of Liquid Hydrogen fuel (much more than the fusion reactor needs) is used to cool the reactor in lieu of radiator fins in addition to cooling crucial jump drive and m- drive components, before being vented out into space or atmo carrying away the excess heat with it. This nicely explains the tremendous fuel requirements for CT/T20 fusion reactors and the enormous amount of jump discharge mass carried as afterall that J-drive must get extremely hot, opening the hole into jump space and we all know that Thruster plates get hot, and there should also be a source of those exotic particles that get trapped close to the plates themselves giving that now famous and characteristic engine glow.

 

[savage]

Drax,
How does that work? Your cooling a nuclear reactor with liquid hydrogen. Doesn't it burn at 130 centigrade (max)?

Savage

 

[veltyen]

Savage,

For some reason I wouldn't suggest storing liquid hydrogen with any ammount of free oxygen nearby.

The concept of running fuel lines arround the drive for cooling and then externally cooling the hydrogen tanks using heat pumps or materials designed to maximise radiant output isn't a bad one however.

At that point waste heat output would only be a worry if it heated the cooling lines to 1,000,000 K or so. An accidental fusion reaction in your cooling lines could be a problem.

Veltyen

 

[Drakon]

No oxygen, no burning.

 

[Commander Drax]

Hi Sorry I'm late rejoining this discussion, in answer to earlier posts re-cooling, yes it may be true that Hydrogen burns at 130c but doesnt water boil at 100c and thats used to cool nuclear power plants all over the world. My take on the liquid hydrogen cooling network within a typical traveller ship is that a great quantity of hydrogen fuel (more than used by the plant itself) is fed through a network of cooling pipes/etc at high speed, which would have the effect of increasing the cooling rate of the plant, before being vented into space/atmo carrying away the excess energy of the fusion reactor and hence maintaining a stable core tempreture, after all something has got to explain the tremendous fuel consumption of fusion plants designed under CT/T20 rules. In TNE powerplant fuel typically lasted a year, not 4 weeks. Whilst I am not an expert, I believe that my explanation is consistent with our modern day understanding of physics, though I am more than willing to listen and adjust my views/opinions if someone more knowledgable can steer me in the right direction.

 

[Drakon]

1) Water boils at 100c AT standard atmospheric pressure. If you increase the pressure, the boiling point goes up as well. Reducing the pressure reduces the boiling point.

2) In a pressurized water reactor, you don't want steam to form in the core. The water flow keeps things from melting down, and steam blocks channels, preventing the core from cooling down locally and this could be very very bad. So one thing they do to prevent that is to pressurize the water, so that even as hot as it is, it don't turn to steam.

3) High speed cooling is effective compared to lower speed cooling. However, allowing a phase change (from liquid to steam) will suck more heat away from your power plant than doing it all single phase. This is really the basic idea behind air conditioning. Heat is carried away by the boiling freon (Or other liquid) which then becomes a hot gas. This gas is compressed, to become a hot liquid, then that liquid is cooled, via heat exchangers.

4) Something has got to explain the huge fuel requirements, yes. This is one alternative. I prefer to think the fuel use rules as broken, and am trying to work around them. To create better, more realistic rules. Unfortunately, I ain't got a good idea how much energy my FTL drive needs yet. sigh.

 

[Commander Drax]

Yeah, I quite agree, Fuel usage rules are definately broken, TNE had a brave try at fixing them, unfortunately the world of developmental physics and real life discoveries ran much faster than GDW could keep up with. I personally am happy to keep the science side of the game, realistic but light, so that it doesn't degenerate into space opera, whilst justifying traveller tech by postulating that greater technological developments not yet discovered, allow the laws of physics as we understand them to be bent to the point of braking, though not actually broken. E.g. gravitic technology...