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Adapter booster M150/T46 (Series) - 14313_19
FMU-152/B ELECTRONIC BOMB FUZE

Aviation Ordinanceman - Aviation theories and other practices
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locking pin for use with the long-delay fuze. This pin locks the adapter booster to the base plug of the bomb and prevents removal of the adapter booster while the fuze is installed. The M150 has a yellow band around the adapter booster casing, which indicates that it is loaded with explosives. ELECTRICAL FUZES LEARNING OBJECTIVE: Identify the various types of electrical fuzes to include their physical description and functional operation. The Mk 376 (fig. 1-6) electric bomb fuze provides an all-electric capability for the Mk 80 (series) bombs with    either    conical    or    retarding    fins,    thermally protected   bombs,   and   laser-guided   bombs   (LGB). Electric fuzes require an electric pulse from the aircraft fuze  function  control  (FFC)  system.  The  FFC  gives in-flight  selection  of  function  delay  and  arming  delay times.    The    376    fuze    is    used    with    the    Mk    43 target-detecting device for airburst capability. DESCRIPTION The  Mk  376  Mod  0  electric  tail  fuze  is  detonator safe. The booster contain 4.3 ounces of tetryl explosive. This  fuze  is  classified  HERO  SAFE,  and  no  unusual RADHAZ   precautions   are   required   under   normal operating conditions. Four discreet dc voltages for in-flight selection of functioning  delay  times  are  used  in  the  Mk  376  fuze. The Mk 31 safety device automatically selects arming delay times. MK 31 SAFETY DEVICE The Mk 31 safety device is used to adapt the fuze to the fuze well of the bomb, provide mechanical safing of the   fuze,   and   unlock   the   timer-decelerometer.   The safety device contains a pop-out pin that locks the fuze in an unarmed condition. The spring-loaded pin is held in  the  safe  position  by  either  a  safety  cotter  pin  or  an arming  wire.  When  the  weapon  is  released  from  the aircraft, the arming wire is pulled from the pop-out pin, allowing the pin to pop out, unlock the decelerometer, thus initiating the arming time. When the free-fall mode of   delivery   is   used   the   Mk   376   fuze,   arming   is completed 10.0 seconds after release from the aircraft. If the Mk 31 safety device senses weapon deceleration (Snakeye fins open), the internal circuits of the fuze are switched, and the fuze becomes armed in 2.6 seconds. The quicker arming time is required to ensure the fuze is fully armed for low-altitude delivery. If deceleration is  not  sensed  by  2.6  seconds,  the  fuze  arming  delay continues to the 10.0-second arming time. FUNCTIONAL OPERATION The  following  description  applies  specifically  to the Mk 376 fuze. Two   arming   delays   are   used   in   the   Mk   376 fuze—2.6   seconds   for   retarded   delivery   and   10.0 seconds    for    unretarded    delivery.    The    appropriate arming  delay  is  automatically  selected  by  the  fuze according  to  the  actual  delivery  mode  of  the  weapon. That   is,   if   the   weapon   does   not   retard,   whether intentionally or unintentionally, the fuze automatically provides a 10.0-second arming delay. At  release,  the  arming  wire  is  withdrawn  and  a charging  voltage  (+300,  +195,  -195,  or  -300  Vdc)  is applied to the fuze. The pilot selects the voltage in flight by the fuze function control set located in the cockpit. The fuze polarity and level of the fuze charging voltage is  important  only  with  respect  to  functioning  delay. 1-10 Figure 1-6.—Mk 376 Mod 0 electric fuze.







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