Ship Sizes

[far-trader]

And yet we have ships, military and civilian, routinely diving to depths in canon, don't we? How do they accomplish this if they are so light? None of them have extensive diving measures like ballast tanks. Unless one imagines flooding fuel tankage for ballast I suppose but I don't recall that being the method described. Actually I don't recall any method being described so maybe it was just left unspoken of, lest belief suspenders snap and put an eye out

 

[Rover]

And yet we have ships, military and civilian, routinely diving to depths in canon, don't we? How do they accomplish this if they are so light? None of them have extensive diving measures like ballast tanks. Unless one imagines flooding fuel tankage for ballast I suppose but I don't recall that being the method described. Actually I don't recall any method being described so maybe it was just left unspoken of, lest belief suspenders snap and put an eye out

I am sure there is a fair bit of handwavium involved. After all Traveller does not take mass into consideration when calculating acceleration, only volume.

Flooding the fuel tanks could work. I suppose a scout or military craft may have calling to double as a submarine, but I would think such ships are purpose built for that. I don't really see much need for a small cargo vessel or civilian ships in general to submerge.

The only exception being a water world with hurricanes raging the surface and the population living beneath the waves to avoid the storms. But that would be a limited occurrence.

I suppose ships operating on a planet with a very high atmospheric pressure may have similar requirements in terms of withstanding pressure, but that is still not the same as submersing.

R

 

[Starviking]

Since both of these reduce to below 0.98Mg/kL, which can itself reduce to 0.98kg/L, one can readily see most ships will float without CG. HEPlaR, however, will do NASTY things to water... :smirk:

True, but all you have to do is turn on your CG and your new increased buoyancy will force you out of the water.

 

[aramis]

True, but all you have to do is turn on your CG and your new increased buoyancy will force you out of the water.

But that CG is a field effect; it'reduces the surrounding water to 0.02kgw/L,while reducing you to 0.0196kgw/L without affecting your mass at all.... you'll fountain quite a bit, but still weigh more than even a dense atmosphere.

 

[Starviking]

But that CG is a field effect; it'reduces the surrounding water to 0.02kgw/L,while reducing you to 0.0196kgw/L without affecting your mass at all.... you'll fountain quite a bit, but still weigh more than even a dense atmosphere.

Does that mean that CG in TNE is broken? I was always under the impression that it rendered craft using it buoyant in air.

 

[Theophilus]

The Super Star Destroyer was never 19000 kilometers long. 19000 meters, maybe, but not kilo meters.

Star Wars Essential Guide to vehicles Pg 46 lists the Eclipse class superstardestroyer at 17.5 Kilometers
an Online reference to the Super Superstardestroyer lists the 19000 kilometer length.

 

[aramis]

Does that mean that CG in TNE is broken? I was always under the impression that it rendered craft using it buoyant in air.

No, only your impression of it...

Std atm is 1.2g/L, btw, and dense would be up to about 1.8g/L, so no, your ship doesn't float in atmosphere... unless it's an empty bulk freighter.

 

[Icosahedron]

What happened to the naval architect guy who was going do some calculations for us? Haven't heard from him in the last few months.

 

[Theophilus]

www.merzo.com lists Vaders Executor class Super Stardestroyer at 19km.

http://www.theforce.net/swtc/ssd.html lists an alternate length of 17.6km for Vaders Executor

Star Wars EGTV lists the Superstar destroyer at 8000m (8km)

www.st-minutiae.com/misc/comparison/index.html gives charts of sci-fi ships

found many more using google-fu

 

[Starviking]

No, only your impression of it...

Std atm is 1.2g/L, btw, and dense would be up to about 1.8g/L, so no, your ship doesn't float in atmosphere... unless it's an empty bulk freighter.

How does that hash with your statement:

"TNE's Contragrav negates 99.99% of interation with gravity; wholly a different thing. In essence, a CG ship floats (in many atmospheres, it's possible that they would...) so a CG ship with even 0.01 G CAN make orbit under TNE on most worlds, and 0.1 G makes even the densest "Solid worlds" landable."

http://www.travellerrpg.com/CotI/Discuss/showpost.php?p=47346&postcount=12

Not being bitchy - this was the first post to show up under a google search for "TNE contragrav"

 

[BlackBat242]

Super tankers are double hulled iirc, partly to contain spills but iiuc mostly for displacement to float with a full load.

So how did supertankers like Exxon Valdez float with a full load?

EV is a single-hulled VLCC (Very Large Crude Carrier) with a displacement of 211,469 tons (214,862 metric tons), and a load of 1.48 million barrels (200,000 t).

Her repairs from her 1989 accident did not change her hull configuration.
After repairs, the Exxon Valdez was renamed the Exxon Mediterranean, then SeaRiver Mediterranean in the early 1990s, when Exxon transferred their shipping business to a new subsidiary company, SeaRiver Maritime Inc. The name was later shortened to S/R Mediterranean, then to simply Mediterranean in 2005.

In early 2008, SeaRiver Maritime sold the Mediterranean to a Hong Kong based shipping company named Hong Kong Bloom Shipping Ltd., which renamed the ship once again as Dong Fang Ocean, now under Panama registry. During 2008, the ship was refitted, converting it from an oil tanker to an ore carrier. Dong Fang Ocean remains in service as of 2009 in this new configuration.


No, double hulls are at least 95% about preventing spills and maintaining buoyancy in the event of a collision (not creating buoyancy to start with, hence the regulations requiring double hulls for passenger liners, inspired by the loss of HMS Titanic).





As an aside, an earlier thread on submerged spaceships in Traveller ended up with a list of depths a ship could submerge to based on hull type & armor factor.

After all, to effectively scoop fuel from as gas giant, the ship will have to get to a sufficient density of hydrogen... which would be at a "depth" with atmospheric pressures well above 14.73psi (1 Terran atmospheric pressure at sea level)... 1 additional atmosphere of pressure equals 10 m water depth (on Terra).

 

[aramis]

How does that hash with your statement:

"TNE's Contragrav negates 99.99% of interation with gravity; wholly a different thing. In essence, a CG ship floats (in many atmospheres, it's possible that they would...) so a CG ship with even 0.01 G CAN make orbit under TNE on most worlds, and 0.1 G makes even the densest "Solid worlds" landable."

http://www.travellerrpg.com/CotI/Discuss/showpost.php?p=47346&postcount=12

Not being bitchy - this was the first post to show up under a google search for "TNE contragrav"

I was mistaken on the %... it's 98, not 99.99. at 99%, yes, turn on the CG, and up you go in dense atm.

 

[Gray Lensman]

Gotta love this place

I could see ships maybe twice the size of today's biggest ocean ships being able to land in special cradles (if the pilot's good enough), say 500k metric tons (35k dT, say 50k), but I doubt if you could go much bigger than that.

Of course, if you're trying to land it on a Starport X, a few hundred dT would probably be your limit.

Thats why I love this Place, ask a question, and you will get enough information to form your own opinion.

Think I will have to go with Icosahedron on this, even for water landings.

Thanks Folks

Dan

 

[rancke]

I've always considered 5000 dT the top limit for ships designed for atmosphere landings, but I can't tell you if it's something I've seen somewhere in canon, or if I (or someone else) made it up.


Hans

 

[aramis]

Hans: I've always used the same limit, but I can't remember where it was I originally lifted it from. but, using a 1:2;4 box ratio, that's 21x41x81m...

 

[Starviking]

I've always considered 5000 dT the top limit for ships designed for atmosphere landings, but I can't tell you if it's something I've seen somewhere in canon, or if I (or someone else) made it up.


Hans

The Hercules Bulk Transport comes in at 5000 dT, perhaps that's where the limit arises from?

 

[Ran Targas]

I would suspect it has everything to do with the planet and starport you are landing at.

It's very different when you're landing at a frontier starport on a 1.5G world with only expose bedrock than if you're landing on at a Class A starport on a .85G world with re-inforced landing bays and parking aprons.

I'm not sure of everything that could be available at a Class A starport to make bringing a big ship in easier but I wouldn't be surprised if anti-grav technology wouldn't be used to support a big freighter where it's structure and landing gear couldn't. Even water filled craters would do an excellent job of dispursing the weight of a large vessel over it's entire hull instead of at its landing gear; if that's something the vessel could survive without structural damage. Some might not.

BTW, ships float because they displace more water than their weight, keeping a portion of their surface exposed to the air (Archimedes was one smart cookie). If entirely surrounded by water, most sink unless their interior is less dense than the surrounding water. Submarines flood or blow air in tanks to change their bouyancy, increasing or decreasing their weight compared to their displacement.

http://science.howstuffworks.com/question254.htm

 

[Icosahedron]

I've always considered 5000 dT the top limit for ships designed for atmosphere landings, but I can't tell you if it's something I've seen somewhere in canon, or if I (or someone else) made it up.

Hans: I've always used the same limit, but I can't remember where it was I originally lifted it from. but, using a 1:2;4 box ratio, that's 21x41x81m...

The Hercules Bulk Transport comes in at 5000 dT, perhaps that's where the limit arises from?

I would imagine you got it from the same place as me:

[IMTU] I limit it to LBB2 ships (5k dT). Anything bigger than that needs a different Pilot licence anyway.[/IMTU]

I usually rule that anything bigger than 5k needs to be custom built as a lander (at additional cost) since larger ships are generally not structurally designed to hit dirt.

 

[cajon5]

DGP's Early Adventures describes the Tukera Long Liner, with MegaTraveller rules. It states that it must either land in water, or use a special contragrav landing cradle. This wasn't due to it's size, however, just the intrinsic strength of the hull; it had less internal bracing than ships meant for regular planetary landfall. In short, the Long Liner seems to be unibody construction, as opposed to a body-on-frame car.