Crashing ships as weapons

[whartung]

That assumes that Jump navigation is *only* inaccurate in time and not only in space - I'd posit that it also has the ship show up a with a similar variable in space (it certainly seems reasonable enough when extrapolating the rules). It's not a factor in normal operations because it's simply not a large enough amount of space (maybe only hundreds or thousands of km) to matter for transit times - but again, vectors and speed make actually targeting a planet when moving that fast more a matter of luck than any actual plan.

As documented, the spatial discrepancy of Jump is only a few thousand kilometers.

And, even with the jump window, planets are pretty big. They make large targets. And the kind of tech necessary to make these kinds of things is, all told, pretty cheap.

So, if I'm determined to send a "planet killer" at a planet, with the goal being, obviously, to "kill the planet", I'll make 20 of these things and boost my odds. What's a Billion Credits here or there if it destroys several trillion credits of economy and infrastructure.

And even then it doesn't mitigate the terrorist threat that's only after a smaller target like, say "Southern California", "Manhattan", or something nice and dense like that.

 

[JimMarn]

The more I've thought about this the more I've pretty much decided that around any inhabited system there is enough "space junk" that it simply doesn't work - especially the highly inhabited higher tech worlds.

Sure, everyone knows it is technically possible, and it's been tried, perhaps even succeeded once or twice - but the vast, vast majority of ships simply run into something large enough to shred themselves before ever getting to the main planet.

Plus, in all honesty, I think that the real problem with this is that Jump navigation isn't actually fine enough to let this happen. If normal variation is variable within hours of the predicted exit point of time, even if the time is taken to fine-tune that, were still down to quarter-hours or minutes - which is going to change the actual vector of approach to the main system pretty significantly - and at near-C speeds there won't be any chance to.

That assumes that Jump navigation is *only* inaccurate in time and not only in space - I'd posit that it also has the ship show up a with a similar variable in space (it certainly seems reasonable enough when extrapolating the rules). It's not a factor in normal operations because it's simply not a large enough amount of space (maybe only hundreds or thousands of km) to matter for transit times - but again, vectors and speed make actually targeting a planet when moving that fast more a matter of luck than any actual plan.

That's before it flies into some leftover sandcaster ammo, or an old satellite part, or defensive mines, or whatever...


D.

There is also, if our solar system is typical, a large Oort Cloud that could go out a light year. A high velocity object heading inwards could create enough gravity to pull in a few asteroids and comets with it.

Not all of them might come in with the ship, but get swung around the target solar system by the gias giants.

On one of the 'How the Universe is Made' show on Discovery, one astronomer postulated that we might be able to get to the Alpha Centauri A-B system by going from Oort cloud here, to that system's cloud. Still slow, but there might be water ice along the way.

 

[BwapTED]

Per Book 2, sand-casters can inflict minor damage on ships/interpose an obstacle that interferes with flight.


If abrasive sand does it in 'normal' space combat, then it seems as if striking micrometeoroids, space junk, or even dust at super-high velocities would indeed be a big problem.

I don't see anything in the text that says star-ships ignore all the small stuff they might run into.

 

[BwapTED]

As documented, the spatial discrepancy of Jump is only a few thousand kilometers.

What would be the effects on setting and game-play if the spatial discrepancy of jump were increased?

 

[AnotherDilbert]

What would be the effects on setting and game-play if the spatial discrepancy of jump were increased?

Nothing much? I have run it that way since before the JTAS article.

You spend a day or so, instead of a few hours, to accelerate to the planet. It still fits easily within the jump every second week schedule.

Since you emerge from jump more isolated, pirates have slightly better privacy.

 

[McPerth]

Since you emerge from jump more isolated, pirates have slightly better privacy.

OTOH, as you emerge from jump at a more random location, they have more space to cover (but so do anti-piracy SDBs).

In any case, as Traveller puts it, they keep close enough from their taget point as not to have great effect...

 

[BwapTED]

RE Vector is preserved through Jump vs emerge at vector 0 relative to nearest massive body house rule


If the craft emerges from jump at a vector of 0 (relative to the nearest massive body), as some have suggested as a house rule, this would seem to negate the use of ships as planet killers.

Conservation of momentum and conservation of energy seem to be the sticking points with this idea, right?

What if the 'missing' kinetic energy becomes the jump flash? A big burst of some kind of radiant energy.


I don't own T5 so I may be misunderstanding what jump flash is.


Or is this nonsensical?

 

[robject]

My ATU is a sundiver / sungate (wormhole) universe with no true FTL, but high-G M-drives are a thing.

That was a very early post, but:

I think Roger Sanger's "AI" sf-rpg was supposed to be a sundiver setting.

Just a stray thought that your post triggered.

 

[Adam Dray]

Is Richard Sanger someone the boards?

 

[whulorigan]

Is Richard Sanger someone the boards?

Roger Sanger is the copyright holder of all of the DGP material.

 

[aramis]

Roger Sanger is the copyright holder of all of the DGP material.

It's been almost long enough that Joe & Gary can recover them... they can, at this point, begin the process.. and since Roger isn't willing to go through the hoops to get them back in sales channels, he also can't do what's needed to establish that he's not simply sitting on it.

 

[BwapTED]

I have created another thread about how the "ton": in 1977 Book 2 rules is a unit of mass and not of volume.

(see pages 10 and 13)

Kinetic Energy:
E_k = m_oc² * {(1 / sqrt [1 - R²]) - 1}, where are R = v/c.

If I assume that 1.0 dton = ~ 10.0 metric tons:

A 100 dton ship masses ~ 1000 mt = 1 * 10⁶ kg​

Therefore:

E_k = (1*10⁶)*(3*10⁸)² * {(1 / sqrt [1 - (0.9)²) - 1} ==>

E_k = 1.165*10²³ J​

Since 1.0 ton of TNT = 4.184 GJ:

E_k = ~ 27.8 Teratons for a 1000 mt mass moving at 0.9c.​

IIRC, the Gigaton range is sufficient to crack a planetary crust and/or alter a planet's orbit in a noticeable way.

He's assuming 1 'd-ton' is 10 metric tonnes.

But what if we go with the original Traveller rules. In those rules, tons measure mass, not volume.

It never does say if that is a long ton, a short ton, or a metric ton, but considering the rules describe the unit a measuring mass displacement, the obvious read to me is the real world displacement ton or long ton.
That's 2240 lbs.

But we could say it's a metric tonne instead, if you like.

The point is, the ship would mass only a fraction of what Whorligan assumes.


Under this straightforward reading of the 1977 rules, then, can star ship be used to smash up planets?

It seems to me the answer is no.

There are implications for the M-drive...

 

[aramis]

I have created another thread about how the "ton": in 1977 Book 2 rules is a unit of mass and not of volume.

(see pages 10 and 13)



He's assuming 1 'd-ton' is 10 metric tonnes.

But what if we go with the original Traveller rules. In those rules, tons measure mass, not volume.

It never does say if that is a long ton, a short ton, or a metric ton, but considering the rules describe the unit a measuring mass displacement, the obvious read to me is the real world displacement ton or long ton.
That's 2240 lbs.

But we could say it's a metric tonne instead, if you like.

The point is, the ship would mass only a fraction of what Whorligan assumes.


Under this straightforward reading of the 1977 rules, then, can star ship be used to smash up planets?

It seems to me the answer is no.

There are implications for the M-drive...

Real world shipping tons are not a measure of mass. Nor are they a measure of volume. They are measured (for ships) in square meters per deck, with both a maximum mass and a maximum volume for each ton. Likewise, a ton of cargo must not exceed the allotted volume nor deck space to be rated as a specific cargo tonnage. Real world ships can be overloaded by either... but it results in excess draft.

CT 77 consistently refers to displacement tons within Bk 2, without defining the term- the term is consistently used in real life for 1 cubic meter of space below waterline at nominal load; most (wet) ships average 4 cubic meters enclosed per displacement ton.

Displacement is always a combination of mass and volume in the real world, and there's no reason to ignore the term used.

 

[AnotherDilbert]

He's assuming 1 'd-ton' is 10 metric tonnes.

It's the velocity term that is big, not the mass term. Reducing the mass will only reduce the energy linearly.

Even assuming 1 Dton is 1 ton, the example would give a kinetic energy of 2.8 Tton_TNT (≈ millions of strategic nukes ≈ ridiculously much).


P.S. "Ton TNT equivalent" is not a mass despite generally called ton, kiloton, or megaton.

 

[BwapTED]

Real world shipping tons are not a measure of mass. Nor are they a measure of volume. They are measured (for ships) in square meters per deck, with both a maximum mass and a maximum volume for each ton. Likewise, a ton of cargo must not exceed the allotted volume nor deck space to be rated as a specific cargo tonnage. Real world ships can be overloaded by either... but it results in excess draft.

CT 77 consistently refers to displacement tons within Bk 2, without defining the term- the term is consistently used in real life for 1 cubic meter of space below waterline at nominal load; most (wet) ships average 4 cubic meters enclosed per displacement ton.

Displacement is always a combination of mass and volume in the real world, and there's no reason to ignore the term used.

But we are not talking about shipping tonnage.

We are talking about displacement tons.

https://en.wikipedia.org/wiki/Long_ton

A unit of mass.


A displacement ton or long ton is 2240 lbs.

It measures mass/weight, not volume.

As these are not ocean-going ships, isn't it strange to read the term as anything other than a mass measurement, when the text mentions mass or weight multiple times and never volume?
The Traveller Book 2 ton seems to be a metric tonne, though, as someone pointed out to me. Trade rules page 44.

 

[BwapTED]

It's the velocity term that is big, not the mass term. Reducing the mass will only reduce the energy linearly.

Even assuming 1 Dton is 1 ton, the example would give a kinetic energy of 2.8 Tton_TNT (≈ millions of strategic nukes ≈ ridiculously much).


P.S. "Ton TNT equivalent" is not a mass despite generally called ton, kiloton, or megaton.

True.

So still a stupendously mighty blow from space.

 

[aramis]

But we are not talking about shipping tonnage.

We are talking about displacement tons.

https://en.wikipedia.org/wiki/Long_ton

A unit of mass.


A displacement ton or long ton is 2240 lbs.

It measures mass/weight, not volume.

As these are not ocean-going ships, isn't it strange to read the term as anything other than a mass measurement, when the text mentions mass or weight multiple times and never volume?
The Traveller Book 2 ton seems to be a metric tonne, though, as someone pointed out to me. Trade rules page 44.

It actually measures submerged (literally displaced) volume at a specified condition (crewed and fueled but with no cargo), which is directly correlated to mass. A submarine's displacement tonnage doesn't change when submerged; its mass does. Likewise, the cargo loading doesn't change the displacement tonnage of the ship even tho it changes the loaded mass and the water displaced. Increase volume below waterline in a refit, and it does change.

https://www.unc.edu/~rowlett/units/dictT.html
Rowlett's Dictionary of Units

ton (DT or dT) [4]

a unit of volume used traditionally to measure the "displacement" of ships, especially warships. One way to describe the size of a ship is to state the volume of sea water it displaces when it is afloat: in other words, the volume of that part of the ship below the waterline. The actual weight of sea water varies somewhat according to its temperature and how salty it is, but for this purpose it has been agreed that a long ton of sea water occupies about 35 cubic feet. Accordingly the displacement ton is defined to be exactly 35 cubic feet, or approximately 0.9911 cubic meter. Since this is a much smaller unit than the register ton, warships have a much higher "tonnage" than merchant ships of approximately the same dimensions. The symbol DT is recommended for this unit.​

 

[whartung]

I cannot see the logic in applying naval warship concepts to starships when the plain English meaning of a displacement ton is 2240 lbs.

You're taking Book 2 out of context, and being overly pedantic.

Regardless of how you may read Book 2, it's clear, and has been clarified, over time, precisely what the intent and meaning of dTon in regards to Traveller Ships means.

GDWs position of dTon has never changed (the value has, drifting back and forth). Per Book 5: "Hulls are identified by their mass displacement (expressed in tons; one ton equals 14 cubic meters) and their configuration." This definition goes along with this quote from Book 5: "The ship design and construction system given in Book 2 must be considered to be a standard system for providing ships using off-the-shelf components. It is not superceded by any system given in this book; instead this book presents a system for construction of very large vessels, and includes provisions for use of the system with smaller ships."

This means that B5 and B2 are both "official" systems for the creation of starships within the game. If the units in Book 2 (specifically tons) mean anything different from the same unit mentioned in Book 5, don't you think there'd be clarification on that matter?

"Hey GDW, I have a 100 ton Scout Ship from Book 2, so, that's 224000 lbs. How many dTons does that take as part of a carried squadron?"

Ever see a question like that? How to covert the mass of ships in Book 2 to volumes for use with Book 5? Anyone? Bueller?

Do you really think that a 4 ton stateroom means a stateroom weighs 10,000 lbs? You think the walls of a stateroom really add up to 10,000 lbs??

Or, does it make more sense that a 4 ton stateroom = 4 * 14 = 56 cu meters, divide by 3 for height gives 18.6 sq meters, square root is 4.3 meters. That's basically a 13x13x9 foot box. That's a good size room. So, 4 tons when used in describing a Stateroom, whaddya think: 10,000 lbs, or a 13x13x9 foot box?

Doesn't that seem to make more sense when laying out a ship and allocating things to it? That things take space? Occupy and demarcate volume? Since starships are big bubbles and boxes floating in space rather than lead ingots?

So, however you're reading it, whatever you think it says, it's abundantly clear what the real intent was when it was clarified in the later parts of the rules. If that wasn't clear enough in the original printing, it's not because the intent changed, that the concept changed, rather it's simply that they felt they didn't need to clarify it further, especially in the very constrained LBBs.

Honestly, I don't know anyone, ever, since 1979 when I first stumbled upon this game, that ever took the "ton" with regards to starships to mean anything but volume.

 

[BwapTED]

Whartung,

I made it quite clear that I'm just looking at Book 2 (1977) for purposes of this tangential discussion.
Of course I agree with you about (nearly) everything after 1979. As you state, it became quite clear what a 'd-ton' is in Book 5.
I don't agree that the designers' intent you see was made clear from 1977 rules. Was volume always the intention? Sure, it might have been.
Or maybe the rules changed and tons were definitely shifted from mass to volume.
M drives seemed to shift from fusion rockets/torch drives in Book 5 1979 (you can use the exhaust as a weapon and it moves you in the opposite direction) to something else in the next edition of Book 5. Stuff does change between editions.

Is there a point in arguing about our respective guesses as to design intent in the very first version of Traveller?

EDIT- All this chatter about mass and volume has put me in mind of some other ship design ideas and questions, which I'll look at in a new post, new thread.

Thanks, Whartung and Aramis!

I''ll keep any further stuff about tonnage in the 'tons' thread,. to prevent more thread drift here.

 

[BwapTED]

What about simply stating that a ship explodes in jump space if it would emerge with over a certain amount of kinetic energy?

Or you misjump if you try coming in over a certain velocity relative to the nearest planetary mass?