The "Best" Measure of
Lethality
(Continued)
Hrdlicka also provides a “rough guide to hunting
effectiveness based on kinetic energy from an archery chart:
< 24 ft lbs.
Small game
25 -41 ft lbs.
Medium game (deer)
42 -65 ft lbs.
Large game (elk, bare etc)
66 ft lbs.
Toughest Game (cape buffalo,
grizzly, etc)
Kinetic Energy
While kinetic energy is very
good at summarizing the key parameters of a weapon, he points out that
a baseball has a lot of kinetic energy and yet it would almost never be
lethal.
Momentum
Hrdlicka argues that momentum
is important, because the momentum is conserved while the projectile is
trying to apply the necessary sheer strength to pierce mammal
flesh. The spear and the atlatl because of the weight of the
missile can have equal or greater momentum provided they are used at
close range (30 to 50 yards). >> See Newton on Penetration >>
Sectional Density
Finally he notes that “a ping
pong ball thrown at a pop can will bounce off. A BB will go right
through”. The difference being sectional density, and
the spear, atlatl and arrow
actually have a better sectional density than firearms.
Their
heavy
projectile’s
momentum
is better conserved as the projectile
pass through flesh (1 gram/cm3) hide and bone (2 gram/cm3).
His final conclusion is:
“All
the
weapons
listed
have
been used for killing, and all have proven
themselves effective. Altalatl darts do not have as much kinetic
energy or momentum as firearms, but have a better sectional
density. They are higher in all three factors than arrows, and
arrows are known to be a very effective weapon.”