Warships in a Small Ship Universe.

[aramis]

We are not talking about aircraft or watercraft, we are discussing crystaliron and superdense hull material that is the equivalent of nearly a foot of hard steel; it is what you get if you look at the starships designed where mass is a factor - MT, TNE, T4.

It needs to be mentioned, tho', that those editions often are off by a factor of two for replicating known armored vehicles. Usually, but not always, generating about 1.5x to 2x the mass of the real vehicle for the given parameters of HWL+SAtW (Height, Width, Length, Speed, Armor thickness, Weaponry). In no small part, due to treating armor as either a warped sphere or a box; actual slanted and curved plates with variable thicknesses.

In this case, Striker gets closer... because it treats each face as a potentially slanted sheet... while MT, TNE, and T4 all treat armor as a uniform shell. And all err on the larger size (essentially, big boxes) and hence mass.

Still, given the known densities established in Striker are armor that's stronger for a given mass, and considerably more massive for a given volume, than our best steel... yes, it is inevitable that BSD derived hulls should be much more massive.

Then again... the concept of different tonnages is nothing new...
Wet Ships are routinely measured by 4 different "tonnages" -

• Mass, in either metric tons, long tons (2240 pounds) or short tons (2000 pounds)
• Displacement Tons: displacement of 35 cu ft of water at a reference temperature and pressure - nominally, one long ton (2000 lbs) of typical seawater at surface. This is, in ideal conditions, also the mass. Note that it also has two values - laden and unladen. I don't recall whether the reference value is laden or not.
• Registry Tons: 100 cubic foot of cargo volume. Nominally, also the allowed lading weight of the hold.
• Freight Tons: 40 cubic feet, or 1.13267 cubic meters.
• TEU capacity - - a TEU is a given maximum size (1520 cubic feet, from an 9'6" x 8'x20' high-cube container), and not more than 26.455 tonnes ("52,910 lb: 47,770 lb (net load) + 5,140 lb (empty container weight).") Nominally, 1, 2, and 2.25 TEU containers are standard, but 2.25 are usually only used above deck, and actual 1TEU containers are usually 8'6" x 8' x 19' 10.5" (1351 cubic feet)...
  Note that a 1000 TEU capacity ship is allowed 26,450 tons of containers in a volume not less than 1,351,000 cubic feet (and probably no more than 1587093.75 cubic feet — 9'6" x 8'3" x 20'3" - 3" bigger than reference.

Traveller uses 3 and infers a 4th...

• Displacement in LHyd. set to any of three values by version of traveller. 13.5 Cubic Meters, 14 Cubic Meters, or 500 Cubic feet.
• Mass, in metric tonnes.
• Cargo Tons - nominally, measured in displacement tons of cargo space.
  MT notes, however, to allocate 1 ton mass per cubic meter. (MT RM p.85)
• TNE notes that ships greater than 10 Tonnes per Ton-Displacement need to have performance be calculated based upon actual mass; less dense may simply use 10 metric tonnes per displacement ton; this infers a cargo ton of not more than 10000 kilograms and not more than 14 kiloliter per cargo ton.
  This hybrid unit is not unlike the TEU as a unit of cargo.

Reference: https://www.unc.edu/~rowlett/units/dictT.html

 

[kilemall]

RL Destroyers-

DD34 Walke, my great uncle's ship, the WWI version- 901 tons full load
https://en.wikipedia.org/wiki/USS_Walke_(DD-34)

DD416 Walke, the WWII version- 2246 tons full load, faster, more heavily armed and much greater range
https://en.wikipedia.org/wiki/USS_Walke_(DD-416)

DD-723 Walke, the second WWII version, was about the same tonnage, a little more armament, but much greater range then even DD416 and a FRAM II upgrade near end of life
https://en.wikipedia.org/wiki/USS_Walke_(DD-723)

Contrast that with the Burkes, a 9-10,000 ton 'destroyer' and higher tech level weapons bays (including most certainly 1-2 missile bays by Traveller terms)
https://en.wikipedia.org/wiki/Arleigh_Burke-class_destroyer

Point being, a destroyer increased 10x in size in just 100 years and arguably 2-3 TLs, and with significantly different missions and capabilities as to what 'destroyer' meant.

I'd say Traveller interstellar navies could assign any damn silly system they want and it would be reasonably RL in practice.

 

[nobby-w]

It needs to be mentioned, tho', that those editions often are off by a factor of two for replicating known armored vehicles.
[...]

And, if you're ascribing 10-15t per dT of hull size, an order of magnitide off when designing known spacecraft. Take (for example) the Apollo command module. A back-of-the-envelope calculation gives you something like 9-10dt displacement with a dry weight of around 12t. The command module was packed solidly with equipment so it's not like there was any significant wasted space. That's an order of magnitude discrepancy with the assumptions OP describes in late-edition Traveller starship design systems. Even with the ~13t of fuel and oxidizer carried (source: Wikipedia) for a total weight in the region of 25 tons (~2t/dT fully laden) it's still a major discrepancy by a factor of around 5-7.

I'll also argue that the Imperial Marine Grav APC described in Striker (as another example) was way too heavy (at 600t) for something you might actually build for that role¹ - especially for a vehicle that was designed to be transported in a spacecraft and used for ground actions in interstellar wars. Sure the Imperium has lots of resources, but you could build a 100-ish ton vehicle with the same armament and enough armour² - and deliver six times as many to the battlefield with the same amount of shipping tonnage.³

Finally, I'll argue that spacecraft have way too much armour in the OTU. If you take the Integration with Traveller section in Striker (and later Traveller editions aren't much different IIRC), you see factor-0 hull armour (like your average free trader) mapping to an armour value of 40 - roughly equivalent to the frontal armour on a cold-war era main battle tank. A real example of a spacecraft that had armour was Giotto, which was sent through the tail of Halley's Comet in the 1980s. This was designed to withstand micrometeorite damage - and sustained some hits. Giotto had (IIRC) roughly half an inch of composite armour (say: AF10 in Striker) and a whipple shield.

This would suggest that, if you assume an actual requirement similar to the armour fitted to Giotto (and go by the rules as published), a Free Trader has an order of magnitude more armour than it actually needs. This makes it a candidate for simple economics. Instead of the armour you could carry paying cargo. The armour is not BSD either - Free Traders are a much lower tech ship; to achieve AC40 at TL9-11 you'd be up for 16.8cm of composite laminates or 8.4cm of crystaliron. That's a lot of cargo you're not getting paid to carry and a lot of fuel you're using to lug all that armour around.

¹ The basic smell test If you were designing a force for a Striker campaign on a finite budget - and actually had to pay for the shipping capacity as well - would you really build a 600t APC?
² For a suitable definition of 'enough', taking into account what actual threats you might want to protect against and what you might accept some vulnerability to.
³ A bit less than six times if you include shipping the crew.

 

[Meteoric Assault]

I have been thinking, why would people use the terminology of battleship and dreadnoughts when talking about 5000 ton ships? Why not revert to the older pre-steal type of naval vessels.

Follow the old English navy tradition:

Primary
Ship of the Line >3000tons Fully Armored, Fully Loaded wpns
1st Class 5000-6000tons Low M and Low Agility
2nd Class 4000-5000tons
3rd Class 2800-4000tons

Heavy Frigates 1000-2700tons Less Armored, Fully loaded wpns
Frigate 500-900 High to Mid M and same in Agility
Corvettes 300-500
Brig 100-300

Courier 100-400 Fast J and/or M Lightly armed
Scout 100-400 like Courier

Naval Merchantmen --- although in fact merchants but used by the navy to
Brigantines 600-1000tons patrol and enforce. Carries cargo but
Sloops 400-600tons also FULLY ARMED.. AND ITS CARGO
Schooner 200-400tons HOLD could hold fighters and missile boats

Heavy Fleet Tender 4000-6000tons Tenders carry non-jump craft, esp
Fleet Tender 1000-4000tons Fighters and Attack Craft or
Light Tender 800-1000tons Missile Boats or Attack Boats

Monitors 600-1000tons Non Jump, heavily armed+Armored
Boats 300-600tons
Attack Craft 50-100tons

Heavy Fighter 50-60tons NonJ High M + Agility
Light Fighter 10-15tons

Heavy Attack Drone 20-30tons
Attack Drone 10-20tons
Recon Drone 5-20tons

Cutters 50-100 Lightly Armed, Non Jump
Pinnace 40-60 (passanger)
Ship's Boat 30ton
Gig 20ton (transport)


This makes a good list.

Now many of these can have SubTypes based on its function.

Battle Major Combat with other Capital Ship
Strike Long Rand Deep Penetration
Raider Attacking Commerce
Escort Escort
Patrol Patrol
Interdiction To Blockade or Interdict a system
Pickett Pickett or stand watch
Q Decoy or Masked Ship (looked as a unarmed merchant)

Just to name a few

Not bad I prefer Increasing the tonnage to reflect the "Industrialized era of Warfare" representations of naval vessels ....

 

[aramis]

Finally, I'll argue that spacecraft have way too much armour in the OTU. If you take the Integration with Traveller section in Striker (and later Traveller editions aren't much different IIRC), you see factor-0 hull armour (like your average free trader) mapping to an armour value of 40 - roughly equivalent to the frontal armour on a cold-war era main battle tank. A real example of a spacecraft that had armour was Giotto, which was sent through the tail of Halley's Comet in the 1980s. This was designed to withstand micrometeorite damage - and sustained some hits. Giotto had (IIRC) roughly half an inch of composite armour (say: AF10 in Striker) and a whipple shield.

This would suggest that, if you assume an actual requirement similar to the armour fitted to Giotto (and go by the rules as published), a Free Trader has an order of magnitude more armour than it actually needs. This makes it a candidate for simple economics. Instead of the armour you could carry paying cargo. The armour is not BSD either - Free Traders are a much lower tech ship; to achieve AC40 at TL9-11 you'd be up for 16.8cm of composite laminates or 8.4cm of crystaliron. That's a lot of cargo you're not getting paid to carry and a lot of fuel you're using to lug all that armour around.

Giotto has an equivalent of 8cm of aluminum. (source: ESA)
Striker's relative values ARE correct against the materials engineering references...

Traveller ships routinely fly as fast or faster than Giotto's expected impact speeds. Giotto vs asteroidal tail was 245000 kmh relative velocity. Roughly 7 G-hours. Many traveller ships do 3+ G hours DAILY, and around 99% of Giotto's relative speed was the comet.

Given Traveller's gravitic drives, and constant 1G thrust or more, armor is needed.

 

[nobby-w]

Giotto has an equivalent of 8cm of aluminum. (source: ESA)
Striker's relative values ARE correct against the materials engineering references...

Traveller ships routinely fly as fast or faster than Giotto's expected impact speeds. Giotto vs asteroidal tail was 245000 kmh relative velocity. Roughly 7 G-hours. Many traveller ships do 3+ G hours DAILY, and around 99% of Giotto's relative speed was the comet.

Given Traveller's gravitic drives, and constant 1G thrust or more, armor is needed.

Typically you need about 2.5x the thickness of Aluminium to realise the same strength as a given thickness of steel, althought the specific gravity of Aluminium is about 1/3 that of steel. Striker doesn't have rules for aluminium armour, but I remember reading that somewhere, maybe in Vietnam Tracks (ISBN 1841768332).

Without a whipple shield, the page cited implies it would have needed 8cm of Aluminium, which is roughly equivalent to 3.2cm of RHA, or 1.6cm of Composite Laminates, giving an armour value of 12-13 if you use the rules in Striker. It's still a lot closer to 10 than 40.

Although not specifically mentioned, it's probably worth noting that you can get clear of the majority of the intra-system debris if you fly out of the plane of the ecliptic. IMO that passes the verisimilitude test a lot better than a free trader with 8cm of crystaliron armour.

 

[aramis]

Typically you need about 2.5x the thickness of Aluminium to realise the same strength as a given thickness of steel, althought the specific gravity of Aluminium is about 1/3 that of steel. Striker doesn't have rules for aluminium armour, but I remember reading that somewhere, maybe in Vietnam Tracks (ISBN 1841768332).

Without a whipple shield, the page cited implies it would have needed 8cm of Aluminium, which is roughly equivalent to 3.2cm of RHA, or 1.6cm of Composite Laminates, giving an armour value of 12-13 if you use the rules in Striker. It's still a lot closer to 10 than 40.

Although not specifically mentioned, it's probably worth noting that you can get clear of the majority of the intra-system debris if you fly out of the plane of the ecliptic. IMO that passes the verisimilitude test a lot better than a free trader with 8cm of crystaliron armour.

And you're still arguing on the side of insufficiency.
3.2cm of steel is a low value... and the whipple shield is a high volume, low mass, composite equivalent.

Traveller starships don't have the option to avoid orbital debris - which will, in many systems, be heavier than earth's.

And they do this not once - nor even just one pass of a flyby lasting a day - but 1-2 days a week for 40+ years.

Further, manned flight past the magnetosphere requires alpha/beta radiation abatement. Metal-mass is actually rather good at that.

Standard armor for Traveller ships is 33cm of steel.

Standard armor for one-use system ships is MT/Striker AV 8 (=2 cm of steel)

For disposables it's MT/Striker AV 4 (1cm).

Apollo would be AV 1.

But MT/Striker both presume (esentially) monocoque designs - the hull shell is also the frame.

Almost no upper stages have been designed as shell-as-frame.

 

[nobby-w]

And you're still arguing on the side of insufficiency.
3.2cm of steel is a low value... and the whipple shield is a high volume, low mass, composite equivalent.
[...]

OK. I'll go with needing loads of armour if you assume the constant acceleration from book 2. This will get you a maximum speed of the order of 1,940km/sec on a trip from Earth-Mars at 380 million km maximum distance. The hypothetical 0.1g particle Giotto was designed to withstand at 68km/sec now has around 1.9GJ of energy, or about 814x the design parameters of Giotto. In comparison, a M829 series APFSDS round has about 12-13MJ of kinetic energy at the muzzle. The same calculation for a similar trip to Jupiter gives a peak speed of the order of 3000km/sec for an impact energy of about 4.6GJ, around 2000x the design spec of Giotto.

That's about 0.01C, by the way - your ship now has an E_k on the order of hundreds to thousands of megatons. If I was (say) in charge of the local planetary navy I'd be looking sideways at shipping going anywhere near that fast around inhabited worlds.

If you go by the book, you'll be needing your 33.6cm of RHA - and then some. I'd still go with flying out of the ecliptic and not running your ship up to relativistic speeds insystem.

 

[aramis]

OK. I'll go with needing loads of armour if you assume the constant acceleration from book 2. This will get you a maximum speed of the order of 1,940km/sec on a trip from Earth-Mars at 380 million km maximum distance. The hypothetical 0.1g particle Giotto was designed to withstand at 68km/sec now has around 1.9GJ of energy, or about 814x the design parameters of Giotto. In comparison, a M829 series APFSDS round has about 12-13MJ of kinetic energy at the muzzle. The same calculation for a similar trip to Jupiter gives a peak speed of the order of 3000km/sec for an impact energy of about 4.6GJ, around 2000x the design spec of Giotto.

That's about 0.01C, by the way - your ship now has an E_k on the order of hundreds to thousands of megatons. If I was (say) in charge of the local planetary navy I'd be looking sideways at shipping going anywhere near that fast around inhabited worlds.

If you go by the book, you'll be needing your 33.6cm of RHA - and then some. I'd still go with flying out of the ecliptic and not running your ship up to relativistic speeds insystem.

Anything you're likely to need to get to is within the ecliptic.

 

[nobby-w]

Anything you're likely to need to get to is within the ecliptic.

The idea is that you leave the ecliptic, travel at speed to somewhere near your destination and slow down when you need to get back into the ecliptic to get to your destination. That avoids the worst of the debris.

Although I'd suggest that you would probably not go anywhere near 0.01C; something like 100km/sec is probably about as fast as it's really safe to go insystem. You could possibly imagine a dedicated in-system barge with a heavy armoured buffer in the front that can go somewhat faster, perhaps a few hundred km/sec. A ship that's primarily designed to jump somewhere near its destination might not need so much protection.

 

[aramis]

The idea is that you leave the ecliptic, travel at speed (although probably nowhere near 0.01C - I'd suggest that somewhere in the region of 100km/sec is about as fast as it's really safe to go) to somewhere near your destination and slow down when you need to get back into the ecliptic to get to your destination. That avoids the worst of the debris.

It still exposes to the same alpha-beta issues. And the same X-Ray and Gamma-Ray issues.

And still has the same terminal issues - which is where most of the issues are - at the endpoints, trapped within the hill spheres.

But even in the deep space, the particulate risk is still 10E-6 grains per cubic meter. That's 1 gain per million m, or per 1000 km, per square meter. 1 per square meter per 278 hours. Or, for a typical Scout Courier 90/278 per hour... or about 1 impact per 3 hours 5 minutes.

Abrasive.

And that's interstellar medium. Interplanetary is denser still.

And, if you're arguing merchants, the loss to armor is far less than the longer, slower courses you're advocating. Sufficiently so as to prevent widespread adoption. The 950 tonnes of cargo off-eccliptic taking a 2 weeks versus 900 tonnes taking 5 days? The cost of the armor still doesn't make it more cost efficient to take the longer course.

And your ideal thinly armored also means 100x the radiation damage to crew and cargo.

 

[nobby-w]

Actually, what I'm suggesting is that it's not possible to put enough armour on a ship to make it safe at the 2000-3000km/sec you might get up to on an interplanetary journey under the Book 2 rules. At 3,000km/sec, a particle collision at 0.1g has an energy equivalent to the explosive yield of 1,000kg or so of TNT; larger particles on the order of a few grams will have energy levels that can be expressed in discernable fractions of a kiloton. Something closer to 100km/sec is about as fast as you could reasonably go safely insystem.

You don't have issues at the terminal points in your course because you've slowed down before you transit back into the plane of the ecliptic.

I'll accept the argument about gamma radiation. You will still need shielding on your crew compartment that's capable of attenuating that down to a safe level.¹ This might or might not be the same as your micrometeorite shielding. Stragetically placed fuel tankage could also help with this.

High guard doesn't closely reflect the real cost of heavy armour, nor does it have any notion of specific impulse of the engines. However, on an actual spaceship made from the sort of materials and construction one might make (say) the Apollo craft from, 8.4cm of crystaliron armour will dominate the mass of the ship. The cost would be a lot more than 5% of your cargo, not to mention the insurance premiums on a ship that's travelling fast enough to expose itself to risk of a crippling micrometeorite collision.

And, as stated previously, the authorities are probably not going to be comfortable with ships travelling that fast around population centres.

¹ And avoiding large sources of gamma radiation like gas giants, but that's a whole different topic.

 

[aramis]

Actually, what I'm suggesting is that it's not possible to put enough armour on a ship to make it safe at the 2000-3000km/sec you might get up to on an interplanetary journey under the Book 2 rules. At 3,000km/sec, a particle collision at 0.1g has an energy equivalent to the explosive yield of 1,000kg or so of TNT; larger particles on the order of a few grams will have energy levels that can be expressed in discernable fractions of a kiloton. Something closer to 100km/sec is about as fast as you could reasonably go safely insystem.

You don't have issues at the terminal points in your course because you've slowed down before you transit back into the plane of the ecliptic.

I'll accept the argument about gamma radiation. You will still need shielding on your crew compartment that's capable of attenuating that down to a safe level.¹ This might or might not be the same as your micrometeorite shielding. Stragetically placed fuel tankage could also help with this.

High guard doesn't closely reflect the real cost of heavy armour, nor does it have any notion of specific impulse of the engines. However, on an actual spaceship made from the sort of materials and construction one might make (say) the Apollo craft from, 8.4cm of crystaliron armour will dominate the mass of the ship. The cost would be a lot more than 5% of your cargo, not to mention the insurance premiums on a ship that's travelling fast enough to expose itself to risk of a crippling micrometeorite collision.

And, as stated previously, the authorities are probably not going to be comfortable with ships travelling that fast around population centres.

¹ And avoiding large sources of gamma radiation like gas giants, but that's a whole different topic.

Specific Impulse under HG drives: Effectively Infinite, albeit limited by drive performance.

Isp is directly a measure of fuel economy...

Oh, and in the OTU, local authorities have no say past 100 diameters. (cited in COACC).

 

[Brandon C]

You know, now I'm picturing a starship version of an Ogre, essentially a flying block of superdense armor ...

 

[CliffBates]

You know, now I'm picturing a starship version of an Ogre, essentially a flying block of superdense armor ...

You mean a Vampire ship?

 

[aramis]

You know, now I'm picturing a starship version of an Ogre, essentially a flying block of superdense armor ...

A 100td scout is about thesize of a Boeing 707...

Or an Ogre Mk I.

 

[Brandon C]

You mean a Vampire ship?

Not quite. Ogres are designed as autonomous, unmanned vehicles. IIRC, those that went rogue generally did not do so because of a virus, but the more classic sci-fi tropes of the AI evolving or breaking it's programming.

Although, other than not being infectious, I'm not sure if those fighting the thing would notice

A 100td scout is about thesize of a Boeing 707...

Or an Ogre Mk I.

I was referring more to the fact that, IIRC, an Ogre is just a block of armor with cavities cut into it for powerplant and computer and with weapon set in recesses. It's actually a bit like an artificial buffered planetoid hull.

 

[wbyrd]

I noticed somethign up above about radiation. If I remember my classes in radiological monitoring right..Alpha particles cant get through your outer skin layers...and a sheet of tin foil will stop them dead.

Beta particles have a bt more punch..but the side of a car,or metal can will stop them can stop them.

Gamma particles can punch through a few feet of concrete ,or a few inches of lead, anything made of dense metals, or some composites can stop those.

oddly enough I remember a bit from a documentary where it was explained an aerogel filled with certain gasses is more than enough to handle all three forms of radiation..so the big threat would be cosmic rays, and neutrons...

I also seem to recall that boron doped polymers are good neutron screens...since they combine both hydrogen, and boron. so if you combined layers of dense ceramic, metals, and boron doped polymers you could have a fairly effective hull material..capable of absorbing small mass impacts, and radiation..it would probably be a descendant of the armor packets on the side of an M-1 Abrams/Leopard/Challenger.


the armor wouldnt need to be a solid block of metal..actually thats the worst way to armor something...mixing materials and layering them to take advantage of the individual materials various properties resuts in armor that has the stoppig power of a heavy cruisers hull plate in a more compact form

. the Abrams has armor that is the same as a 3 foot plate of solid steel...but noticeably thinner than RHA plate.

if you added some spaced plates on the outer shell, to soak up the dust particles, which are the most common debris, then a layer of aerogel filled with some inert gas, that would be more than enough to stop the bulk of the debris before it got to the heavy protective layer.

the dust hits the outer plate, vaporizes and expends it's energy in the areo gel....larger particle hit the reinforced inner layer, and dump that energy into the armor...

knocking a nasty dent/hole in it, causing small ruptures, or loss of sea on the interior but not punching through the ship.

anything bigger the sips radar/lidar could detect and then the autopilot can avoid it. Even a one gee lateral shift is a pretty solid defense against a rock moving in a reasonably predictable course.

 

[aramis]

The problem with Alpha/Beta is that, at the speeds ships travel, their penetration is much enhanced, and there's the secondary radiation cascade to deal with - both particulate and non. Add to that that the microscopic physical impactors are effectively high powered rifle bullets...

And the inert gas? it's gone the first time you hit a pebble. Aerogels won't even significantly slow that from what i've read.

 

[nobby-w]

The problem with Alpha/Beta is that, at the speeds ships travel, their penetration is much enhanced, and there's the secondary radiation cascade to deal with - both particulate and non. Add to that that the microscopic physical impactors are effectively high powered rifle bullets...

A bit more than rifle bullets at the 3000km/sec that a 1G Earth-Jupiter trip could get up to on a Book 2 style journey (The maximum Earth-Jupiter distance is roughly equivalent to the 1B km journey listed on Book 2 P10). 0.1g at that speed will give you an impact energy on the order of 5x10⁸J - roughly equivalent to the explosive yield of 100kg of TNT.¹ Even going Earth-Mars wlll get you up to 1-2000km/sec depending on the relative position of the bodies.

E_k of a 0.1g particle at:

• 1km/sec (muzzle velocity of a rifle): 50J - equivalent to a fairly powerful air gun.
• 10km/sec (orbital velocity): 5kJ - equivalent to a rifle bullet.
• 100km/sec (a bit faster than the closing velocity between Giotto and Halley's Comet): 500kJ - equivalent to 30mm cannon shell.
• 1000km/sec (peak speed of a modest interplanetary journey by Book 2 rules): 50MJ - about 4x the muzzle energy of a 120mm M829 series APFSDS round.
• 3,000km/sec (peak speed of a Book-2 style Earth-Jupiter journey if aligned in opposition): 450MJ - about 35x the muzzle energy of a M829 series round.

¹ Correction to an earlier calculation that was out by a factor of 10.