Mongoose Traveller - Aurora-class Starfury

[Lorcan Nagle]

Hmmm, perhaps some of these ships replace the grapple with a missile launcher.

They were B5's own Starfuries, and it's only seen in this one scene (though it's in the Season 5 opening credits too). Given Thirdspace is st between the Shadow War and B5/Earth Civil War, it could be an experimental upgrade B5 tried to increase the firepower of their starfuries in anticipation of fighting Clark loyalists.

Best way to handle it would be a variant that either removes stuff like the grapple (which we only see once or twice in the show anyway), or reduce engine power to represent the increased mass of the missiles slowing the ship down.

Don't the star fury's use the grapple in the Thirdspace to drag the Artefact out of hyperspace?

It's been ages since I saw Thirdspace, but I dobut they could have just used the grapples to pull the artifact out. The Grapple is seen very clearly in "Soul Hunter", and it's just a simple claw/robot arm type assembly, so at best they'd just be holding onto cables with the grapple.

 

[pasuuli]

So, how "big" are B5's Hyperspace drives? Don't some fighters have them (or is that reserved for very high tech small ships)? Do they shrink drastically with technological change?

I think only Shadow fighters have them - but anyone can enter hyperspace through a Gate. - B5 Ships are big - I think the White stars are as big as a present day aircraft carrier and it is a super fast , super maneuvable strike ship - they do take time to charge hence jump gates. Does Traveller do them because they are big thing in B5. Also you can get lost in hyperspace.............unless you are a Shadow

Right you are, B5 ships are huge compared to Traveller ships, too. Can we get away with a scale modifier there, some sort of handwave like "when I say 100 tons in Traveller, I mean 100 meters long in B5" (i.e. scale everything up - generous, wide corridors, spacious suites, huge weapon emplacements, cavernous hangar bays) and "when I say 100 EPs in Traveller, I mean 100 Terawatts in B5"?

 

[Rikki Tikki Traveller]

That might work. It seems to me the problem is at the large ship end.

Traveller ships of the line are typically in the 100Ktn to 1Mtn range, while B5 ships run into the multi-megaton range.

Drop all the big ships down by a factor of 10 and use that.

Thus a 1.5Mton B5 ship become a 150KTn Traveller design. And a Traveller Tigress becomes about the same size as the largest B5 warship (5Mtons).

The small ships need to stay the same though, I cannot see a fighter being much smaller than 10 dtons

 

[pasuuli]

So, when I read that the Vorchan cruiser is 600 meters long, well I plug that into some formula that bang presto tells me what Traveller hull volume it uses.

Something along the lines of...

volume = length, more or less, but use your brain, if length <= 100m.
volume = ((length/10)^3)/10, for length > 100m.

So it's a 600,000 ton hull in B5, but designed on a 21,000 ton hull using MHG. Or the Sharlin, which is more like 10 million tons, is designed in a 400,000 ton hull.

And the Vorlon planet-killer... well, that's no moon, that's a space station...

 

[pasuuli]

So, how "big" are B5's Hyperspace drives? Don't some fighters have them (or is that reserved for very high tech small ships)? Do they shrink drastically with technological change?

I think only Shadow fighters have them - but anyone can enter hyperspace through a Gate. - B5 Ships are big - I think the White stars are as big as a present day aircraft carrier and it is a super fast , super maneuvable strike ship - they do take time to charge hence jump gates. Does Traveller do them because they are big thing in B5. Also you can get lost in hyperspace.............unless you are a Shadow

Traveller has postulated jump gates, and we have ideas on how to design them, but none exist I think. The reason jumpgates don't exist in the Traveller default setting is because of the setting assumption that small spacecraft cannot enter jumpspace (TNE is an exception to this, though). A jumpgate would violate that principle, in the default Traveller setting. In a B5 setting, however, it is routine and expected.

Jumpgates would probably behave differently in the Traveller setting than the B5 setting. Traveller does not use hyperspace (i.e. a dense subspace medium that compresses regular space, allowing you to maneuver from one point to another in a fraction of the time it would take in normal space). Instead, it uses a wormhole-like jumpspace that your ship moves through in isolation, in transit to an intended destination. But this is only an in-game distinction, rather than a design difference. I expect a jumpgate constructed in MHG to look and behave like a B5 jumpgate, when inserted into a B5 setting.

Jump Gate = Jump Drive

The Traveller jumpgate is a big jump drive (or perhaps a jump projector) attached to a power plant, with a computer and some basic operational sensors. The drive launches a targetted ship into jumpspace. Some people prefer that a receiving gate be present at the destination, while others don't care.

The cost and technology level would probably be very high.

Example: Small Jump Gate Using Jump Drive-Z and Power Plant-Z, the Small Jump Gate can push a 2,000-ton ship 4 parsecs, an 1,800-ton ship 5 parsecs, and a 1,200-ton or less ship 6 parsecs. Fuel tankage of 48 tons supports one jump of any ship up to 2,000 tons (in B5, this tankage is probably just an extension of the drives, requiring no fuel). The drives are controlled by a computer Model/6, running Jump/6. The system uses basic military sensors for external control.

Note: The ability to push craft into jumpspace probably requires a very high tech drive mechanism, so listed cost is probably not correct.

Total volume: 248 tons
Total cost: MCr 453.6


Jump Gate = Jump Power

An alternate view of jumpgates is that they impart power to a ship's on-board jump drive, so the jumping ship doesn't need a big power plant and doesn't need a lot of fuel. This also sets a size limit based on how big of a jump drive the ship can carry: since the smallest drive is 10 tons, your ship must be larger than 10 tons. This model breaks down when transferring between B5 and Traveller, since the jump drive's size is a direct measure of its performance, whereas in B5 the drive simply opens a portal into subspace.

 

[pasuuli]

So, when I read that the Vorchan cruiser is 600 meters long, well I plug that into some formula that bang presto tells me what Traveller hull volume it uses.

Something along the lines of...

volume = length, more or less, but use your brain, if length <= 100m.
volume = ((length/10)^3)/10, for length > 100m.

Taking the Vorchan as an example, assuming its length is 600m*:

volume = (60 x 60 x 60)/10 = 21,600 tons.

In the "Azhanti High Lightning" thread, I posted a very tentative drive table:

     Jn  %vol   Mn  %vol           Pn  %vol
     1+  Jn+1   1   1              1   1.5
                2   1.2            2   2.0
                3   1.5            3   2.5
                4+  Mn/2           4   3
                                   5+  2 x (Pn-3)

It needs a jump drive of course. A Traveller cruiser would require Jump-4 at least, so say Jump-5.

The Vorchan has an antimatter reactor. That does tend to make it high tech. What say it has the same strength of a regular power plant, but no fuel required, and we adjust that to whatever makes sense later.

It's supposedly "fast" -- whatever that means. Maybe 4G for now.

It's fascinating that its main weapon is a twin plasma cannon -- never heard of a plasma "spine" before, but reality comes later. Spines in Traveller are in the thousand-ton ranges, requiring hundreds of EPs, and plasma weapons are energy-hungry; hence the antimatter powerplant.

Ah, they have energy shields. Unless we give it a white globe, this will map to Meson Screens, Nuclear Dampers, and Repulsors (to fend off missiles).

Vorchan Cruiser:     21,600 tons
Light Armor:            ??? tons
Bridge:                 432 tons
Jump-drive (J5):      1,296 tons
Jump fuel            10,800 tons
Power plant-10:       3,024 tons    Antimatter: same volume, no fuel required
Maneuver (4G):          432 tons
Twin Plasma Spine:    2,500 tons    Needs as much energy as the M-drive?
Pulse Cannon Bays:      800 tons    16 x 50-ton bays
Missile Bays:           200 tons    2 x 100-ton bays
Shield:
- Meson Screen:         100 tons*  
- Nuclear Damper:       100 tons*   *All incorrect, I know
- Repulsor:             100 tons*
Crew Quarters(100):     400 tons    How many people?  100?  400?
Fighters (16):          800 tons    50-ton fighters?
                        616 tons remaining

*NOTE Until we know how long the Vorchan *really* should be, that length-to-volume formula used above should be considered mostly wrong. My apologies.

 

[AKAramis]

Canon traveller does have jump-gaesd, but they're TL18+, and lead to pocket universes. There are only a handfl, and they are all in the marches. (See Secret of the Ancients, Adv 12)

 

[Da Boss]

Hmm Jump Gates are very different in B5 - anyone can build them including the EA - anything can enter them including fighters and probably - if you really stupid / sucicidal / odd / unlucky, someone in a vacc suit!

You can get lost in hyperspace if you loose locks on the "beacons" and it may be that travel in hyperspace is only possible because of the Beacons - which I think are also the Jump Gates. I don't recall it saying who built the first ones - The First Ones?

Eveyone (includingVorlons) uses jump gates / engines - except the Shadow and perhaps the First Ones.....................Jump Gates are also, I think, regarded in the same way as BattleTech Jump Ships - ie Lostech that it is forbidden to destroy - probably to avoid the loss of the ability to navigate hyperspace if too many are lost - again similar to BattleTech.

 

[pasuuli]

Hmm Jump Gates are very different in B5 - anyone can build them including the EA - anything can enter them including fighters and probably - if you really stupid / sucicidal / odd / unlucky, someone in a vacc suit!

You can get lost in hyperspace if you loose locks on the "beacons" and it may be that travel in hyperspace is only possible because of the Beacons - which I think are also the Jump Gates. I don't recall it saying who built the first ones - The First Ones?

Yes, beacons are the part of the jumpgate that extends into subspace, I believe -- er, hyperspace I mean.

Spot on, jumpgates behave very differently in Traveller, but that's a paragraph in a rulebook, not a design constraint. Traveller allows designing the gates, and the setting dictates their behaviour.

AKAramis is talking about matter-portals, which are a legit though unbuildable kind of gate.

The main departure is that in B5 jumpgate construction is common.

 

[Da Boss]

Of course there are also various versions of some ships just to confuse the issue - people's extrapolations of the Show, AOG's work and Mongooses's own ACTA (which of course varies ins ome cases from edition to edition.

(in ACTA - the one I know most about)
the Vorchan is a very fast - faster than many fighters normally (Centauri ones whcih are about average in speed, move 12", Vorchan moves 14, 21 (faster than any fighter in the game) if all power to engines). it is maneuvable but does not carry fighters. Its weaponary is Ion Cannons and Plasma Accelerator. Defences are non existant except for moderate armour. Its variant is the Demos - switches Plamsa for missile battery and gains an inteceptor battery - is that like your sandcaster? - it defends the ship against non "beam" weapons but can be overwhelmed.

vearing of course for a moment I picked up 2nd hand recently 2 sourcebooks for the "Jovian Chronicles" which seem to be very detailed (but not dry) and well done fleet books - they also look lovely.............have you come across them..........?

 

[pasuuli]

Of course there are also various versions of some ships just to confuse the issue - people's extrapolations of the Show, AOG's work and Mongooses's own ACTA (which of course varies ins ome cases from edition to edition.

(in ACTA - the one I know most about)
the Vorchan is a very fast - faster than many fighters normally (Centauri ones whcih are about average in speed, move 12", Vorchan moves 14, 21 (faster than any fighter in the game) if all power to engines). it is maneuvable but does not carry fighters. Its weaponary is Ion Cannons and Plasma Accelerator. Defences are non existant except for moderate armour. Its variant is the Demos - switches Plamsa for missile battery and gains an inteceptor battery - is that like your sandcaster? - it defends the ship against non "beam" weapons but can be overwhelmed.

vearing of course for a moment I picked up 2nd hand recently 2 sourcebooks for the "Jovian Chronicles" which seem to be very detailed (but not dry) and well done fleet books - they also look lovely.............have you come across them..........?

I've not seen the Jovian Chronicles, but I know they exist

From a very pretty B5 site, I've found lots of nice data on handfuls of Earthforce, Narn, Centauri, and Minbari ships. And while the numbers may not be accurate, they certainly seem to be in correct proportions to each other. It's got lengths and images (whence aspect ratios) for the ships' main dimensions, which should suggest a volume.

The Vorchan, then, is 600m long, and has an aspect of 20:5:5 and 33:2:8, where the "20" is the 600m. So its dimensions seem to be 600:150:150 and 1000:60:240, for a volume of about 28 million cubic metres.

Since the Vorchan is a "small" cruiser, I'd want to translate that to 28,000 Traveller displacement tons. Do I just divide by 1000? I'd have to calculate more ship volumes before I know how to translate them.


The Sho'Kar is 500m long, with an aspect of 20:2:2 and three 19:6:2, with the "20" translating to 500m. So, 500:50:50 + 3 x (475:250:50), for a total volume of 19 million cubic metres. Maybe 19,000 Traveller tons.


The Minbari Nial fighter, 22m, aspect 27:5:5. 22 x 4 x 4 = 352 cubic meters, but this thing has to be between 10 and 50 Traveller tons. The divisor is between 7 and 35. Probably between 7 and 17.

The Narn commercial transport, 30m, aspect 32:12:8. 30 x 11 x 7.5 = 2475 cubic metres, and is probably a few hundred Traveller tons. The divisor is between 2 and 24. Possibly between 2 and 10.

The Minbari Flyer, a Courier, 40m, aspect 20:4:4. 40 x 8 x 8 = 2560. I can easily see this being 100 to 300 Traveller tons. Divisor ranges from 8 to 25.

For these small ships, a divisor of 8 might work. But for larger ships, a divisor has to be around 1,000.

A Narn Bin'Tak, 1900m, aspect 35:15:10. 1900 x 810 x 540 = 831 million cubic metres. Definitely want to divide by 1,000.

An Earth Alliance Olympus Corvette, 450m, aspect 24:7:7. 450 x 130 x 130 = a bit over 7.5 million cubic metres. Probably should divide by 1000, since 7,700 tons is a very healthy size for a cruiser escort.

Earth Alliance Warlock Destroyer, 2000m, aspect 30:5:5. 2000 x 333 x 333 = 222 million cubic metres.

Minbari Sharlin Cruiser, 1600m, aspect 32:17:17. 1600 x 850 x 850 = 1.1 billion cubic metres.

So, a function like this:

f(length in metres) = Traveller vol in tons

Where f(10) = 10 or so, and f(2000) = 800,000 or so.

But even then it's going to be wrong sometimes. The function should use volume, I suppose. So it needs to be

f(cubic metres) = Traveller vol from 10 to 1,000,000 tons.

f(350) = 20 to 40 tons.
f(1,100,000,000) = 600,000 to 900,000 tons.

 

[pasuuli]

How about:

f(volume > 10,000 cubic metres) = Traveller tons = sqrt(vol) x 10.
f(volume < 10,000 cubic metres) = Traveller tons = volume / 10.

Here are B5 examples mixed with Traveller examples.

f(maximum volume=10 billion)          = 1 million tons
f(Tigress dreadnought=2.5 bil)        = 500,000 t
f(minbari sharlin=1.1 bil)            = 332,000 t
f(narn bin'tak=830 million)           = 288,000 t
f(ea warlock=222 mil)                 = 150,000 t
f(smallest dreadnought=100 mil)       = 100,000 t

f(heavy cruiser=49 million)           = 70,000 t
f(vorchan=28,000,000)                 = 52,900 t
f(sho'kar=19,000,000)                 = 43,600 t
f(ea olympus=7.5 million)             = 27,400 t
f(typical light cruiser=6.2 million)  = 25,000 t
f(smallest cruiser=1 million)         = 10,000 t

f(Sloan-class Cruiser Escort=250,000) = 5,000 t
f(centauri transport=51,840)          = 2,270 t

f(Kinunir strike cruiser=14,400)      = 1,200 t

f(smallest destroyer/escort=10,000)   = 1,000 t
f(mercenary cruiser=8,000)            = 800 t
f(liner=6,000)                        = 600 t
f(fat trader=4,000)                   = 400 t
f(Gazelle-class close escort=3,000)   = 300 t

f(narn commercial=2,475)    = 250 t
f(minbari flyer=2,560)      = 260 t

f(free trader=2,000)        = 200 t
f(scout/courier=1,000)      = 100 t

f(cutter=500)    = 50 t
f(nial=352)      = 35 t
f(fighter=100)   = 10 t

 

[AKAramis]

The canonical displacement ton is 14 cubic meters, and for civilian vessels runs roughly 10 tons metric of mass when "dry".

For warships that approaches a dry mass around 20tons metric per displacement ton.

When converting vessels, remember, there is a lot of "non-ship space" inside the bounding box described by L:W:H tristats. Few B5 designs approach even 50%; the Whitestar, for example, looks about 30% of the bounding box volume. The Centauri Light Cruiser is really about 1/20th the volume of its bounding box.

What is really needed is a good set of meshes, and then have the interior volume checked electronically when scaled to "good numbers".

For example, the Whitestar is listed at several sites as 475.6m long with a mass of 6.8million tons. (sorry, I don't buy this number: the bridge windows are only 2.5m tall on the set, which puts her about 150m-200m long. Another fan site lists her at 280m long.) Going by a bounding box with aspect 4:3:1, she's got 12 blocks of 475.6/4=118.9m/side, or a whopping 20,170,970cubic meters, 1.4MTd... at a more reasonable 200m, thats 1.5Mm^3... now (roughly a million displacement tons), correcting for being only 30% of that volume, 300,000 tons... the whitestar fits nicely in the battleship range. (either way, she fits in the battleship range. And we know she's small.

Now, working from the 6.8million tons, being a warship, lets err on the side of caution: 20 Metric tons per displacement ton. 340,000 Tons Displacement.

So the bounding box is just not a good measure, due to the non-regular-geometry nature of the ship's shapes.

 

[pasuuli]

Oh, I knew from the start that bounding box doesn't work. What I did was measure out the major components to the ships and jot down their dimensions. So I'm approximating what a mesh would do, with much lower resolution. I agree that a mesh would be great but I don't have that kind of skill -- maybe someone has already done this.

Secondly I don't dare translate B5 ships 1:1 into actual displacement tons, because they are generally huge, so I want to translate them into a typical High Guard design range. Kind of a normalization process, if you get my drift. Because fourteen million cubic metres in Babylon 5 doesn't equal a million tons in Traveller -- in B5 it's not a superdreadnought, it's just a medium cruiser.

Another thing that doesn't seem to work is using mass to determine volume, because density seems to vary greatly between ships (is it due to armor thickness, which also varies, or are other factors just as important?).

Finally -- and this is why I went ahead and did this -- B5 ship measurements appear arbitrary. Therefore, any system which does a reasonable approximation is likely to be just fine, until someone comes up with trustworthy numbers.

 

[AKAramis]

Oh, I knew from the start that bounding box doesn't work. What I did was measure out the major components to the ships and jot down their dimensions. So I'm approximating what a mesh would do, with much lower resolution. I agree that a mesh would be great but I don't have that kind of skill -- maybe someone has already done this.

Secondly I don't dare translate B5 ships 1:1 into actual displacement tons, because they are generally huge, so I want to translate them into a typical High Guard design range. Kind of a normalization process, if you get my drift. Because fourteen million cubic metres in Babylon 5 doesn't equal a million tons in Traveller -- in B5 it's not a superdreadnought, it's just a medium cruiser.

Another thing that doesn't seem to work is using mass to determine volume, because density seems to vary greatly between ships (is it due to armor thickness, which also varies, or are other factors just as important?).

Finally -- and this is why I went ahead and did this -- B5 ship measurements appear arbitrary. Therefore, any system which does a reasonable approximation is likely to be just fine, until someone comes up with trustworthy numbers.

Mass is pretty constant due to armor and weapon tonnages. Warships are generally close to 20, and bottom out at 12ish; whilst pure cargo ships tend to run 9-15 MG per Td. If the mass numbers are reliable, use the role.

But beware fan sites; there is a nasty tendency to inflate the size of ships in fandom. But when converting, DO NOT SHRINK THE SHIPS. Redefine the terms instead. If a ship is 200x50x150m, and fills about 30% of the bounding box, she really should be that size, a whopping 450,000kL, or 32,142 or so TonsDisplacement.

Shrinking them means you're not playing the "real thing"...

Oh, and one of the better analysis sites is http://www.babtech-onthe.net/ as they walk you through their calculations. Just so happens my rough guess of 150-200m is for the Whitestar is agreed with by them.

 

[Deniable]

Has anybody got miniatures and a measuring cup? I'm starting to think it would be easier to measure the displacement and scale the results. It's going to have negative buoyancy so it should all be volume of the solid, right.

 

[AKAramis]

Has anybody got miniatures and a measuring cup? I'm starting to think it would be easier to measure the displacement and scale the results. It's going to have negative buoyancy so it should all be volume of the solid, right.

It should work nicely; just remember to (gently) cap the mount holes, and slowly lower the mini into the water. But a gradiated cylinder will be needed, as will a catchbasin. If you have a decent gradiated cylinder, use a pipette to get it to a nice reference point, then drop the model in, and subtract the reference point from the new measure.

 

[Traveller-61]

Just to add to the "missiles on Starfuries" thing - by the time of the Lost Tales (10 years after the formation of the ISA) both Starfuries launched to dock with B5 carry 4 Omega class missiles each. So it looks like they are pretty standard by then.

DW

 

[pasuuli]

But when converting, DO NOT SHRINK THE SHIPS. Redefine the terms instead. If a ship is 200x50x150m, and fills about 30% of the bounding box, she really should be that size, a whopping 450,000kL, or 32,142 or so TonsDisplacement.

Shrinking them means you're not playing the "real thing"...

Well, the goal here is to use MHG to construct them, so the only thing that gets redefined is the "ton". So in the Traveller setting, you're building a Plankwell. Exported to the Babylon 5 side, it will be 400 million cubic meters, and 1000m (or more) wide.

I think what you'd rather see are lifted size restrictions, which also requires larger weapons. I suppose it's preferable, since B5 uses different weapons as well... but at that point I'm wondering why bother B5 ships with MHG -- in other words, this thread assumes there's something interesting in basing them on a single design system, even to the point of being able to mix and match them.

By the way, http://www.babtech-onthe.net/ is a great site. I waffled over whether or not to use its estimates; since its calculations are ranges, I'd still have to make a somewhat arbitrary decision. The site that has the hyperinflated ship sizes, on the other hand, is quoted across fan sites, and has a sort of glamour standing.

That said, I'd prefer to use the more scientific guesses from babtech-onthe.net.

 

[Lorcan Nagle]

Has anybody got miniatures and a measuring cup? I'm starting to think it would be easier to measure the displacement and scale the results. It's going to have negative buoyancy so it should all be volume of the solid, right.

It should work nicely; just remember to (gently) cap the mount holes, and slowly lower the mini into the water. But a gradiated cylinder will be needed, as will a catchbasin. If you have a decent gradiated cylinder, use a pipette to get it to a nice reference point, then drop the model in, and subtract the reference point from the new measure.

Will scale matter for this? The ActA minis aren't produced to scale with one another.