Rules Only: Traveller Armor and Damage into RL units

[Dragoner]

Layers work with dissimilar material, such as a penetrator hitting RHA, resisting force, and then a layer of ceramic that might be less force resistant, except more resistant to heat. Armor is really a fascinating subject, I loved it in school.

 

[atpollard]

OK then. On one of my Don Quixote conversion projects to and from Traveller, I would like to convert Traveller armor ratings (vehicles and spacecraft armors) into actual cm (or inches for the metricly impaired) thickness of steel or other material in RL.

I have no idea if THIS is of any use to you at all, but I am familiar with shell thicknesses and column/beam slenderness ratios to prevent buckling. I always wondered what the MINIMUM hull thickness for a starship was (10 dTon Fighter vs 100,000 dTon Dreadnought) ... so I calculated it:

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The "Striker" claimed 40cm "High Guard Armor 0" (which may be enough to protect against radiation and micro-meteor impacts) is strong enough for any ship up to 20,000 dTons. The thickness above are steel (RHA), so they can be reduced based on the armor tables for future magic materials. It comes down to a linear relationship between the "radius" (span) and the "thickness" with a constant that changes with configuration and material technology. This comes close enough for a first-order approximation without getting into questions like "joint details" and "section modulus of members" and "moments of inertia".

Note that ships larger than 20,000 dtons require greater than Armor 0 just to avoid breaking in half under acceleration. The figures in the table should be roughly 2G rated with a safety factor of 2 [indicating the ship is allowed 2G and buckles at 4G]. Doubling the thickness should double the G rating, etc.

As a quick ballpark, this works out to a minimum of 1% of the total volume to HULL thickness (per 2 G rating).

Now if we can just convert thickness of RHA [equivalent] to D6 damage stopped ... (like when a FGMP shoots a Free Trader in a starport as it takes off).

 

[Condottiere]

Well, nickel iron requires five percent for structural integrity at armour factor zero, and seven and a half percent per armour factor.

That would be pretty thick.

 

[infojunky]

Note that they are not compatible, Striker uses an exponential armour rating and FF&S uses a linear rating, i.e. if you double the thickness of the armour TNE gives double armour rating, but Striker adds +8 to the rating.

Mind you the difference between the two systems TNE applies the exponent in weapon penetration not armor rating...

 

[infojunky]

High Guard armor is in magical units … (% of ship) … tiny ships are as hard to penetrate as a shell thicker than the entire tiny ship on a large ship.

Yes and no.

Consider how armor is used in Book 5 i.e. it's ablative. Looking at that one finds that Hull "Armor" is more that just thickness of plating, While thickness is a factor, appropriate other damage resistance measures are in there as well. Such as the extent of compartmentalization.

 

[kilemall]

Well, nickel iron requires five percent for structural integrity at armour factor zero, and seven and a half percent per armour factor.

That would be pretty thick.

For that sort of fudge handling I just presume as internal hull amount rises relative to external hull a higher percentage of the armor tonnage budget goes to bracing. Of course with Striker material values that thickness goes down.

Spinward Flow did analysis re hull thickness for his modular ship case studies so some of us will go there.

For my part I justify the hardpoint limit to be an engineering one with the RAW limit imposed due to a combination of bracing, bulkhead and cables/lines having considerable redundancy yet not impinge greatly on usable internal volume.

Since I have a lot of fuel tankage being ersatz rad/hit surface armor as per LBB5 hit tables, there isn’t a lot of room left around the skin for extra weapons, especially swappable between lasers and missiles.

However I worked out a house rule system for that to be variable- less hardpoints like some of the civilian standard types are a bit tougher, more hardpoints then the allowable means the ship is more fragile and more prone to speed limits and ultimately breaking apart. The model for that is Imperium Terran Missile Boats.

That’s done by tracking on hull points as damage and tying hull state to allowed G rating and potential system loss like power distribution, life support, controls, etc.