Ship's armor

[mike wightman]

According to canon, planetoid hulls are made by selecting an appropriately sized planetoid and then using fusion power to tunnel out the spaces for ship systems.
A planetoid 'wastes' 20% while a buffered planetoid 'wastes' 35% of available interior volume.

I do not think armour is slapped on the outside in order to up-armour them. More likely the planetoid hull receives further reinforcement and the spaces inside are constructed as armoured boxes.

This makes more sense in HG and TNE where armour volume matters, rather than in MT where armour volume is free.

 

[McPerth]

This makes more sense in HG and TNE where armour volume matters, rather than in MT where armour volume is free.

Yes, but it weights a lot, and, as I understand your POV wil lbe more like using the ship's mass to multiply the armor modifier, it would lead to the massive weights I told about, so severely limiting their agility (and so their survivalty in combat).

 

[aramis]

But in non-planetoid hulls, the armor is the hull, while in planetoids, following your way (as I say, I see logic on it), it's an added shell over the hull, not part of it. That's why I talked about needed bracing that is not needed in other hull configurations.



Not for MT ,AFAIK.

The only canonical planetoid (buffered in this case) ship I'm aware about is in CT:S9 (page 44), but, aside from being CT (and so mass is not a factor) it has no armor above the integral for a buffered planetoid (and BTW, its lack of meson screen makes it quite vulnerable to Meson fire).

There's one in Expedition to Zhodane, as well.

 

[AnotherDilbert]

I do not think armour is slapped on the outside in order to up-armour them. More likely the planetoid hull receives further reinforcement and the spaces inside are constructed as armoured boxes.

Wouldn't that be rather inefficient?

My point:
Our 1000 dT planetoid ship is roughly a sphere with a radius of 14,8 m. if we slap 0,5 m of armour around it, that would be a radius of 15,3m or a sphere of ~1105 dT, we have used around 105 dT or 1417 m³ of armour (21262 tonnes?).

If instead we create say ten armoured spheres inside the ship: Each interior compartment would be 80 dT = 1000 × 80% / 10. An 80 dT sphere has a radius of 6,37 m, add 0,5 m and we get a radius of 6,87 m enclosing about 100 dT. Each compartment uses 100 - 80 = 20 dT armour, so all ten of them uses around 200 dT or 2700 m³ of armour (40500 tonnes?). It should also somehow consume 200 dT interior volume.


I used spheres since that is the most efficient way to armour something and easy to calculate. "Armoured boxes" would be even more inefficient.

 

[AnotherDilbert]

That's why I talked about needed bracing that is not needed in other hull configurations.

I can't pretend to have given it that much thought, and that was 30 years ago...

In order to affix the armour shell to the planetoid we would have to sink tabs of armour material down into the planetoid? With heavy armour we could let the tabs or shafts go straight through the planetoid as bracing?

 

[mike wightman]

You prove my point for me.
A 1000t ship with armour slapped on the outside is now an 1105t ship and thus the drives must be built for the new hull volume if you track armour volume (which MT doesn't).
Build it with drives for a 1000t ship and its performance is downgraded.

Alternatively you have to start with a planetoid of 895t displacement and slap your 105t of armour on the outside to make the total 1000t.

Using a planetoid as a hull is already inefficient volume wise.

 

[Condottiere]

I tend to think if you have a hollowed out planetoid, additional armour would be layered inside, and tonnage factored on the remaining eighty percent.

 

[mike wightman]

I tend to think if you have a hollowed out planetoid, additional armour would be layered inside, and tonnage factored on the remaining eighty percent.

Yup, that's the only way I can see it working too.

 

[aramis]

I tend to think if you have a hollowed out planetoid, additional armour would be layered inside, and tonnage factored on the remaining eighty percent.

ALso, keep in mind, modern research says "until they get self-rounding, most are not big enough to actually consolidate into solid bodies"...

According to Lineweaver & Norman (2010) the minimum for rounding at all is a few km semi-major axis (which tends to be a 2:1 with the semi-minor, IIRC), so let's be generous and give a 6:1 for our example, and assume "few" is 3km semi-major, and thus about 0.5km... (4/3)πr³ or (4/3)πr₁r₂r₃... so 4*6*0.5*0.5*π/3=12π/3≅ 12.5667 km³ or some 897,621,428.6 tons.

Realistically, we're not likely to see actual planetoid hulls, as suitable planetoids are astrophysically implausible... as they require both relatively consolidated metal asteroid and sizes well under the consolidation likely level.

Oh, and they note that icy objects self round to near-spheres around 200km, and rocky around 300-400km...

 

[AnotherDilbert]

You prove my point for me.
A 1000t ship with armour slapped on the outside is now an 1105t ship and thus the drives must be built for the new hull volume if you track armour volume (which MT doesn't).
Build it with drives for a 1000t ship and its performance is downgraded.

That is how regular hulls work in MT. Armour is added on the outside without affecting the drives.

Does it make sense? No.
Do we have to live with it? Yes.

 

[Condottiere]

It seems implied in Mongoose that nickel iron planetoids are selected.

I'm also working on smallcraft class whose hulls that are extracted during the hollowing out process as a byproduct, rounded off and called Neweggs.

 

[aramis]

It seems implied in Mongoose that nickel iron planetoids are selected.

I'm also working on smallcraft class whose hulls that are extracted during the hollowing out process as a byproduct, rounded off and called Neweggs.

They're still not generally thought to be solid until over 100km; below 2 km, electrostatic attraction is sufficient, and that is generated by solar wind ionization...

 

[mike wightman]

That is how regular hulls work in MT. Armour is added on the outside without affecting the drives.

Does it make sense? No.
Do we have to live with it? Yes.

I know it doesn't make sense
In Striker you had to calculate the volume of the armour and subtract it from available space, and yet for MT they dropped it. Then in TNE they brought it back.

CT HG % is just as silly - a 100t hull with 14% armour has the same armour factor as a 100,000t hull that also allocates 14%.

 

[McPerth]

There's one in Expedition to Zhodane, as well.

Glad I specified "that I am aware about". I didn't know about this (I guess) adventure...

I can't pretend to have given it that much thought, and that was 30 years ago...

Frankly, same here

In order to affix the armour shell to the planetoid we would have to sink tabs of armour material down into the planetoid? With heavy armour we could let the tabs or shafts go straight through the planetoid as bracing?

I guess it would have to be quite strongly braced, or it risks to be taken away quite easily, more so as it recives combat pounding.

ALso, keep in mind, modern research says "until they get self-rounding, most are not big enough to actually consolidate into solid bodies"...

According to Lineweaver & Norman (2010) the minimum for rounding at all is a few km semi-major axis (which tends to be a 2:1 with the semi-minor, IIRC), so let's be generous and give a 6:1 for our example, and assume "few" is 3km semi-major, and thus about 0.5km... (4/3)πr³ or (4/3)πr₁r₂r₃... so 4*6*0.5*0.5*π/3=12π/3≅ 12.5667 km³ or some 897,621,428.6 tons.

Realistically, we're not likely to see actual planetoid hulls, as suitable planetoids are astrophysically implausible... as they require both relatively consolidated metal asteroid and sizes well under the consolidation likely level.

Oh, and they note that icy objects self round to near-spheres around 200km, and rocky around 300-400km...

And yet, they are integral part of most (if not all) Traveller editions...

That is how regular hulls work in MT. Armour is added on the outside without affecting the drives.

Does it make sense? No.
Do we have to live with it? Yes.

I don't see armor as just thougher hulls, but I see your point.

In any case, see that weight (came it from armor or other components) does not affect the MDs at all in MT (though it affects agility).

BTW, you always talk about the weight modifier as mm of steel. Where do you take this conversion from? I don't remember having read anything about it in MT...

 

[AnotherDilbert]

I know it doesn't make sense

The system designers have to choose an acceptable level of simplification. If we had to accurately dimension and place every ventilation duct, no-one would bother making ships. MT at least makes a reasonable effort to model armour.

My personal pet peeve is systems that should be proportional to mass, but instead are proportional to volume, like M-drives. I do not like it, but it makes ship design much simpler.

 

[AnotherDilbert]

In order to affix the armour shell to the planetoid we would have to sink tabs of armour material down into the planetoid? With heavy armour we could let the tabs or shafts go straight through the planetoid as bracing?

I don't see armor as just thougher hulls, but I see your point.

If we add enough armour we can wonder what use the planetoid really is? It just consumes space and add mass for very little benefit.

BTW, you always talk about the weight modifier as mm of steel. Where do you take this conversion from? I don't remember having read anything about it in MT...

The Armor Table on p63 is directly taken from Striker where the Mod is explicitly cm of hard steel.

So, Armour 40 is Mod 33 = 33 cm of hard steel.

 

[Timmy]

This was laid out in Imperialines Newsletter issue 1. Multiple power plants is ok. Also, not allocating life support equipment tonnage to the fuel tankage areas.

 

[AnotherDilbert]

This was laid out in Imperialines Newsletter issue 1. Multiple power plants is ok.

No?

As far as I can see Imperiallines Newsletter #1, p7-8 describes how you can reduce power output from your single power plant to reduce fuel consumption.

Note that the design examples all have a single 990 MW power plant.

 

[McPerth]

No?

As far as I can see Imperiallines Newsletter #1, p7-8 describes how you can reduce power output from your single power plant to reduce fuel consumption.

Note that the design examples all have a single 990 MW power plant.

The net practical result is the same, isn't it?

 

[McPerth]

We have to reason around this:

SPARE SYSTEMS
Spare systems may be installed in a craft to take over in the event that the main unit is disabled.
These are backup devices and may not be in operation at the same time as the main device. The higher-output device is the mainstay; the backup device does not consume fuel or power while it IS not in use. When the main device takes damage that reduces it below the level of the backup, the backup takes over. If the backup is then damaged, the main unit returns to action. Whichever unit has the highest current factor is the one In operation; when damage is received, it is applied to the unit in operation. Under no circumstances may a backup and main device be operating at the same time.

As an aside, see that, regardless this rule, there's at least one official design (Purcell-class Express Boat Tender, in HT page 81) where ths rule is broken:

Four computers are provided because if the jump drive is engaged along with everything else, one computer is insufficient to handle the data load.