the shape of things to come

Internal structure is a common term in today’s ’Mech and vehicle design
circles. In general, it refers to the underlying framework of a BattleMech,
IndustrialMech, ProtoMech or Combat/Support Vehicle. In aerospace parlance,
this same concept is known as “structural integrity,” and is loosely
defi ned as an aircraft’s or aerospace fi ghter’s airframe, or the framework of
larger aerospace craft, such as DropShips and other capital ships.
The internal structure or structural integrity of a ’Mech, vehicle or fi ghter
is the part of the unit that holds all other parts together—the skeleton, as
it were (though ’Mech designs incorporate actuators and myomers as part
of this package as well). If damage aff ects these areas, the unit is generally
considered compromised—often terminally so—and so very few vehicles
are ever sent into the fi eld without at least some armor protection to avoid
damage to the structure itself, be it from weapons fi re or simple wear and
tear.
AEROSPACE STRUCTURE (STRUCTURAL INTEGRITY)
Introduced: Pre-spacefl ight (conventional aircraft), 2020s (aerospace
craft/spacecraft)
Whether discussing an aircraft or aerospace fi ghter’s airframe or the
inner framework of a DropShip, the structural integrity (SI) of an aerospace
craft serves as its primary means not only for mounting armor, engines
and equipment, but also ensuring that the entire collection can withstand
the g forces expected of the craft without coming apart. Smaller aerospace
vehicles, such as fi ghters, actually wed their airframe design into
the armor itself, essentially rendering the skeleton of the craft inseparable
from its protection against weapons fi re, but larger vessels—including
Small Craft—devote extra tonnage to reinforcements and the like.
ENDO-STEEL INTERNAL STRUCTURE
Introduced: 2487 (Terran Hegemony)
Extinct: 2850 (Inner Sphere)
Recovered: 3035 (Draconis Combine)
Endo-steel internal structure was designed especially for use in
BattleMech skeletons, about the only form of unit fl exible enough to effi -
ciently employ it. Using zero-G manufacturing techniques that uniformly
blend an exotic steel alloy, the process produces ’Mech “bones” that are
INTERNAL STRUCTURE
twice as strong per unit of weight as standard structural materials, but with
a signifi cant increase in overall bulk made necessary by larger-diameter
segments. The processes to create this type of ’Mech structure were lost
during the early Succession Wars, when military orbital factories became
favored targets for raiders. The Draconis Combine, however, managed to
recover the techniques shortly before the War of 3039, and debuted them
on such newly deployed units as their Hatamoto series.
Clan endo-steel, of course, is more refi ned, allowing for a reduced loss
of internal space, but even this reduction cannot overcome the limitations
that prevent the use of this innovation in non-’Mech units.
INDUSTRIALMECH STRUCTURE
Introduced: 2350 (Terran Hegemony)
The IndustrialMech skeleton diff ers very little from that of the standard
BattleMech, but is composed of heavier, somewhat less effi cient materials
and bulkier myomer bundles. The resulting chassis is less resilient under
weapons fi re, but better suited for the stress of regular sustained labor rather
than physical combat. As a result, the frame of a typical IndustrialMech
weighs about twice as much as that of a comparable BattleMech.
Over the years, a few performance-obsessed designers have attempted
to overcome the weight issues associated with IndustrialMech chassis by
using BattleMech skeletons—even endo-steel, when available—to lighten
the load. This approach, however, is simply a cheat on the construction
standards that have applied to ’Mech manufacturing industries since the
Age of War, as it eff ectively builds a IndustrialMech as a BattleMech. Put
simply, any ’Mech chassis built using industrial structure is formally classifi
ed as an IndustrialMech (and subject to the design standards of said
vehicles). Conversely, any built using BattleMech skeletons are offi cially
regarded as BattleMechs.
The trials of the Succession Wars and the expediency of keeping military
and industrial standards separate for various logistical reasons have combined
over the centuries to reinforce these eff ectively arbitrary standards,
so that even today the two classes practically never mingle. It is simply
easier (and cheaper) to produce IndustrialMechs to IndustrialMech standards,
and leave the more expensive and durable BattleMech skeletons
where they belong.
Tech Base: Inner Sphere (BattleMech [Standard and IS endo-steel], IndustrialMech, Combat Vehicle, Support Vehicle, fi ghter, Small Craft and DropShip);
Clan (BattleMech [Standard and Clan endo-steel], IndustrialMech, ProtoMech, Combat Vehicle, Support Vehicle, fi ghter, Small Craft and DropShip)
Unit Restrictions: See chart
Table Reference: See chart
Game Rules: Internal structure/structural integrity is considered structural and cannot be “deactivated” during combat through engine shutdown
or pilot/crew injury.
Construction Rules: The chart below indicates the availability of the featured internal structure/structural integrity types to particular unit types,
as well as their construction rules page references and main weight (and points) tables. ‘Mech internal structures that occupy critical space may
break up their slots and spread them across the overall design to make room for other components; OmniMechs may not move these spaces around
once they are determined for the base design.
Table Reference: See Chart
INTERNAL STRUCTURE
Structure Type Unit Availability Construction Rules Reference Weight/Points Table
BattleMech (Standard) BM p. 46 ‘Mech Structure
BattleMech (Endo-Steel) BM p. 46 ‘Mech Structure
IndustrialMech IM p. 66 ‘Mech Structure
ProtoMech PM p. 82 ProtoMech Structure
Combat Vehicle CV p. 98 Vehicle Structure
Support Vehicle SV p. 121 Vehicle Structure
Fighter (Structural Integrity) CF, AF p. 187 Aerospace Structure
Small Craft/DropShip (Structural Integrity) SC, DS p. 187 Aerospace Structure
Key: BM=BattleMechs, IM=IndustrialMechs, PM=ProtoMechs, CV=Combat Vehicles, SV=Support Vehicles, CF=Conventional Fighters, AF=Aerospace Fighters, SC=Small Craft, DS = DropShips
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