Game Development Reference
In-Depth Information
To model the effects of body armor penetration in your game simulations, you could equip
your soldiers, law enforcement officers, or whomever with one of the types of body armor listed
in Table 12-1. When a bullet strikes the person wearing the body armor, compute the kinetic
energy of the bullet at impact. If the kinetic energy is greater than the value listed in Table 12-1, the
bullet can be considered to have penetrated the body armor.
You will need to consider some other things when modeling body armor. For example, the
armor generally only protects the torso of the wearer, and the person wearing the body armor
could still be wounded if hit in the arms, legs, or face. Even if the body armor stops the bullet,
the wearer may still be wounded by the blunt trauma caused by the impact. We'll discuss blunt
trauma a bit later in the “Body Wounds” section when we talk about the momentum transfer
caused by a ballistic impact.
Animal Skin Penetration
In some game simulations, hunting games for instance, the targets won't be wearing steel
armor but will depend only on their hides for protection. There are also game situations in
which the projectiles won't be bullets but will be arrows instead. Table 12-3 shows the approx-
imate kinetic energy required of an arrow in order to penetrate the hide and cause a mortal
wound to a whitetail deer and to larger game such as elk and moose. A typical hunting arrow
with a mass of 0.034
kg
that strikes its target at 61
m/s
has a kinetic energy at impact of 63.3
J
.
According to Table 12-3, this arrow would kill a deer but would be unable to kill a larger animal
such as a moose.
Table 12-3.
Arrow Penetration Data for Various Targets
Projectile
Target
Required Kinetic Energy (
J
)
Hunting arrow
Whitetail deer
61
Hunting arrow
Larger game (elk, moose, etc.)
75
With some consideration, it's possible to extend the data shown in Table 12-3 to human
targets as well. A villager wearing a leather shirt might have a similar penetration resistance
as the hide of a whitetail deer. It is known that an arrow shot from an English longbow could
penetrate chain mail armor at a range of 100
m
. If the longbow arrow weighed 0.06
kg
and
struck the target at a representative velocity of 55
m/s
, this would imply a kinetic energy at
impact of about 90
J
.
Momentum
We have discussed how the kinetic energy of a projectile determines whether a projectile will
penetrate a target. There is another factor to consider when evaluating the damage caused
by a ballistic impact—that of the momentum transfer caused by the impact. We saw in Chapter 6
that a force is required to change the momentum of the object.
dmv
()
F
=
(12.8)
dt
