M904E2/E3/E4 MECHANICAL IMPACT NOSE
FUZE
The M904 (series) fuze (fig. 1-1) is a mechanical
impact nose fuze used in the Mk 80 (series) low-drag
general-purpose (LDGP) bombs. The M904 (series)
fuze is installed in the nose fuze well of the bomb and
requires the use of an adapter booster. The fuze is
detonator-safe, and it contains two observation
windows through which you can determine the
safe/arm condition of the fuze. There is no special
locking feature designed into the fuze for shear safety if
the bomb is accidentally dropped. However, detonation
is unlikely if the collar (forward end of the fuze) is
sheared off by the accidental drop before arming is
complete.
The fuze may be configured for a number of
preselected arming and functioning delays needed by a
mission. There are nine arming delays from 2 to 18
seconds in 2-second increments, and any combination
of six functioning delays from instantaneous to 250
milliseconds (0.250 seconds) may be selected. An
internal governor, driven by the permanently mounted
arming vane, allows relatively constant arming times at
release speeds ranging from 170 to over 525 knots.
Functioning
times
are
determined
by
the
installation of an M9 delay element. Any one of six
delay elements may be installed. Each delay element is
identified by the functioning delay time stamped on the
element body—NONDELAY (instantaneous), 0.01,
0.025, 0.05, 0.1, or 0.25 second.
1-3
Figure 1-1.—Mechanical impact nose fuze M904 (series).
