M904E2/E3/E4 MECHANICAL IMPACT NOSE FUZE

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).