Armour and Protection

Work in progress

This wiki is still being written. Pages are incomplete, numbers may change, and some mechanics are not covered yet.

Every part carries a weakness multiplier that thins its armour and boosts incoming penetration at the same time. Higher means weaker, and the value differs for kinetic and chemical rounds.

The armour multiplier

Every part in the game carries a weakness multiplier $m$ . It is the single number that decides how much a part actually resists, and it applies to both sides of the penetration check at once.

t_{\text{eff}} = \dfrac{t}{m} \qquad\qquad P_{\text{eff}} = P \cdot m

Rolled steel sits at 1. A higher multiplier means a weaker part, because it divides the thickness down and multiplies the incoming penetration up.

Read the table the right way

Higher is weaker. A multiplier below 1 is tougher than steel, and the very high values on crew, ammunition and wheels mean those parts barely stop anything at all.

The multiplier tables

There are two tables, one for kinetic rounds and one for chemical rounds. Name beats material, and a part can override either table with its own attributes.

Part	Kinetic	Chemical
RHA	1	1
CHA	1.064	1.064
HHRA	0.8	0.8
Composite Screen	3.25	1.6
NERA	1.65	0.7353
ERA	per part	per part
Structural Steel, Breech	3	3
Bulletproof Glass	1.5	1.5
Aluminium, Fuselage	5	5
Aluminium Alloy	2	2
Engine, Cannon, Transmission	4	4
Drives, metal wheels, Glass	6	6
Ammo, Fuel, Radio, APS	20	20
Crew, Tracks	30	30
Rubber wheels, Wood, Rotors	50	50

HHRA at 0.8 is the toughest plate here. NERA is weak against kinetic at 1.65 but strong against chemical at 0.7353, which is exactly what it is built for.

Reactive armour and tandem warheads

ERA reads its multiplier from the individual brick rather than a fixed table value, and there are two special interactions on the shell side.

Case	Multiplier used
Tandem chemical shell, first ERA contact	Treated as 50, so the precursor spends one brick for free
AntiERA or kinetic round hitting ERA	Four times the brick’s kinetic value, falling back to 50
Any round of 20 mm calibre or larger	Destroys the ERA brick it touches

Note

A tandem warhead therefore beats exactly one layer. Stacking more than one reactive or spaced layer is what actually stops it.

Why spacing works

Spaced armour does not stop a chemical jet by being thick. It works by forcing the jet to cross air, and a jet loses three percent of its rated penetration for every calibre of air it crosses.

P \leftarrow \operatorname{clamp}\big(P - 0.03\,P \cdot \tfrac{280.112}{C} \cdot g,\ 0,\ P\big)

g is the gap in studs between one contact and the next. The first contact is free.

Note

Kinetic rounds are almost unaffected by gaps. They lose penetration to distance flown and to the plates themselves, which is covered on the penetration page.

Thin armour and overmatch

Below a certain thickness armour stops mattering, because a large enough calibre overmatches it outright. An overmatched plate cannot bounce a round and does not bend its path.

\text{overmatched} \iff \dfrac{C}{M} > \dfrac{t}{m}, \qquad M = \begin{cases} 3 & \text{AP, APHE} \\ 6 & \text{APDS, APFSDS} \\ 7 & \text{HEAT, ATGM} \end{cases}

Screens, thin roofs and light structure fall into this band against most main guns.

Armour and Protection

The armour multiplier #

The multiplier tables #

Reactive armour and tandem warheads #

Why spacing works #

Thin armour and overmatch #

See also

The armour multiplier

The multiplier tables

Reactive armour and tandem warheads

Why spacing works

Thin armour and overmatch