
 DOESTD301496
where:
m=
effective missile mass;
Vt
Vm
e
=
coefficient of restitution
;
(68)
Vo
Vo =
velocity of missile before
impact.
For the entire aircraft impact (which is relatively deformable) on hard
structures, e is between 0 (plastic impact) and 1 (elastic impact). The
value of e is estimated based on the relative mass and stiffness of the
target and the missile. If the value of e cannot be easily estimated,
the lower and upper bounds of Ea can be calculated as in Paragraphs
e and f below.
e. Lower Bound Ea: A lower bound Ea can be obtained by assuming a
plastic impact (i.e., the aircraft moves along with the target after
impact), for which e equals zero and is less than m/Me. For such
cases,
m/Me
1
2
mVo
Ea
.
(69)
1 m/Me
2
f.
Upper Bound Ea: An upper bound Ea can be obtained by assuming an
elastic impact (i.e., the aircraft and the target velocities after impact
are different), for which e=1. For such cases,
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