How thick is BT Armor?

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Karagin
08/14/02 09:47 AM
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Anyone wanna hazard a guess?
Karagin

Given time and plenty of paper, a philosopher can prove anything.
Bob_Richter
08/14/02 10:00 AM
4.35.174.250

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Psycho, do you remember?
-Bob (The Magnificent) Richter

Assertions made in this post are the humble opinion of Bob.
They are not necessarily statements of fact or decrees from God Himself, unless explicitly and seriously stated to be so.
:)
CrayModerator
08/14/02 10:18 AM
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The Star League Sourcebook indicated the Mackie's armor (in one location hit by an AP shell) was "finger thick."

I believe the MW1 RPG book described it as "centimeters thick."

Which is all quite reasonable. Mechs have HUGE surface areas and a few tons for armor.

Let's see. The armor is definitely a two-layer mix of steel and boron nitride (so sayeth MW1 RPG). ASSUMING the armor is half steel and half boron nitride by thickness, and densities of 8g/cc and 3.5g/cc respectively...average armor density is 5.75g/cc.

And ASSUMING we're talking about an Atlas with 19 tons of armor...

And ASSUMING the Atlas is 10m tall, 3m thick, 3m wide rectangle [1] for a surface area of 138 square meters, then gratuitously increased 50% to allow for all the folds, additional surface areas of limbs, etc [2]...that's 276 square meters.

Areal density is 72.46kg of armor per square meter, average, or 7.246 grams per square centimeter.

Armor thickness, at 5.75g/cc, is 1.26cm, or just about a half inch. [3]

Comments:
[1] This an extremely conservative area estimate because 10m is the height of a squat and/or light mech and 3m is the width of a narrow one like the Assassin. The Atlas is neither a short mech nor a narrow mech.
[2] You could actually probably double the area to allow for all the extra surfaces of limbs and mechs in general (which are freakin' shot traps). Or you could get motivated and calculate surface area limb by limb.
[3] Of course, armor thickness varies. The head armor is something like 1/5 as thick (or so) as the front center torso armor. The 1.26cm is an average, but, noting comments [1] and [2], it is an estimate leaning toward the upper end. An Atlas may well have 3 or more times as much surface area as I estimated, which would reduce armor thickness to 4 millimeters (average).
Mike Miller, Materials Engineer

Disclaimer: Anything stated in this post is unofficial and non-canon unless directly quoted from a published book. Random internet musings of a BattleTech writer are not canon.
Karagin
08/14/02 10:20 AM
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Now if what you say is on the mark how far does this armor go to protecting the mech?
Karagin

Given time and plenty of paper, a philosopher can prove anything.
CrayModerator
08/14/02 10:35 AM
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>Now if what you say is on the mark how far does this armor go to protecting the mech?

Eh...very far, obviously. The 1-2cm on an Atlas's CT will stop two HGR shells at short range, won't it?
Mike Miller, Materials Engineer

Disclaimer: Anything stated in this post is unofficial and non-canon unless directly quoted from a published book. Random internet musings of a BattleTech writer are not canon.
Karagin
08/14/02 10:37 AM
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Sorry I meant over time from wear and tear as well as combat.
Karagin

Given time and plenty of paper, a philosopher can prove anything.
CrayModerator
08/14/02 10:40 AM
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Eh...very well, I guess. Mech armor seems fine after centuries in a bunker. Damage from falls is indicative of "worst case" normal operational damage. Monthly mech maintenance costs are, like, 200 to 250 C-bills, IIRC, so there can't be too much worn out armor on a monthly basis (standard armor is 10,000 C-bills a ton, right?)
Mike Miller, Materials Engineer

Disclaimer: Anything stated in this post is unofficial and non-canon unless directly quoted from a published book. Random internet musings of a BattleTech writer are not canon.
CrayModerator
08/15/02 02:37 PM
12.91.151.41

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1) 20th Century Tank armor isn't necessarily solid. Spaced armor is enormously weight effective stuff.
2) Normal mech armor is not woven per se. There are reinforcing fibers in the boron nitride, but they are probably not woven (weaving reduces strength), and are simply cast in place when the boron nitride is sintered around the fibers.
3) Mech armor shows no resemblance to normal Kevlar body armor, and only the most general resemblance to Kevlar fibers in resin matrices. Kevlar body armor consists of woven and non-woven layers of Kevlar designed to disperse energy by tugging fibers straight (and relying on the raw strength of the fibers to keep the bullets from penetrating.) The mechanisms that steel/ceramic mech armor work are considerably different: there's projectile shattering and ablation you don't see with Kevlar.
4) The cross-sectional diagrams I've seen of the Abrams indicate a frontal- and turret-armor thickness on the order of a foot or two, with top and underside armor being about 1 inch of RHA steel. That composite armor on the Abrams covers a fraction of the area of the Atlas, on the order of 10% or less (perhaps as low as 2.5% of the Atlas's area) and approaches twice the Atlas's armor mass.

Look at picture 7 in the following link. That's a diagram from General Dynamics, maker of the Abrams (appropriated by AFV modelers):

M1A2 Cutaway

Note the hollow trapezoid directly ahead of the driver's feet: that's the frontal armor, a laminate of steel, dense metals, ceramics, and polymers. (I'm still trying to figure out what kind exactly, besides uranium). The roof, rear, and belly armors are clearly thinner - about an inch of steel.
Mike Miller, Materials Engineer

Disclaimer: Anything stated in this post is unofficial and non-canon unless directly quoted from a published book. Random internet musings of a BattleTech writer are not canon.
MadWolf
08/16/02 10:34 PM
134.53.144.88

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Armor Really dosen't Decay does It? Would Its Make up allow for rust and things? I mean It would be like Keeping a car Body up ( sorry lack of options ) Keep it clean, dry and Out of the Extreem temps. If It Expands or contracts to heat or lack of it may cause it to warp, I.E. Each battle the thing runs with 5 heat Points and the Mobile repair field is in 6 ft of snow.... Any Ideas???
Nothing is Impossible, It is only Improbable.
Karagin
08/18/02 02:44 PM
63.173.170.162

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Rust is decay...armor rust...if you get a chance go to Abeerdeene Proving Grounds and look at their tank park...alot of the tanks have rust and holds do form from it...
Karagin

Given time and plenty of paper, a philosopher can prove anything.
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