Physical Description
The M904 (series) fuze contains approximately 1
1/2 ounces of tetryl in the booster, which is located at
the base of the fuze body. The entire fuze weighs about
2 1/3 pounds and is 9 1/4 inches long.
The M904E4 is a thermally protected fuze. It is
especially designed for use with the thermally
protected Mk 80 (series) general-purpose bombs and
the thermally protected M148E1 adapter booster. This
significantly increases the cook-off time (table 1-1) of
the bombs subjected to intense heat or flame.
REVIEW NUMBER 1 ANSWERS
A1.
A fuze controls bomb detonation.
A2.
The time or number of vane revolutions
needed for the firing train to align after a
bomb is released is the arming time.
1-4
Item
Ordnance
Fuze/Adapter
Booster
Average
Reaction
Time
(Min & Sec)
Shortest
Reaction
Time
Bomb
Initiated
Reaction
Fuze Booster
Initiated
Reaction*
Bomb
H6 and
PBXN
109
filled
Mk 82, 83, 84
unprotected
All
3 + 30
2 + 30
Deflagration
to explosion
Deflagration
to detonation
(after 5
minutes)
Mk 82 Mods/
BLU-111
M904E4 with
M148E1
Adapter,
FMU-152,
FMU-139
10 + 00
8 + 00
Deflagration
Deflagration
to detonation
(after 12
minutes)
M904E2/E3
with M148/T45
6 + 00
5 + 00
Deflagration
to detonation
M148T45
(no fuze)
3 + 04
Deflagration
to detonation
(denotation
may occur
after 5
minutes)
Mk 83 Mods/
BLU-110
thermally
protected
M904E4 with
M148E1
Adapter,
FMU-139/B,
FMU-152
10 + 00
8 + 49
Deflagration
Deflagration
to detonation
(after 12
minutes)
Mk 84 Mods/
BLU-117
thermally
protected
M904E4
with
M148E1
Adapter,
FMU-139/B,
FMU-152
10 + 00
8 + 45
Deflagration
to detonation
(after 12
minutes)
* Fuze or booster initiated reaction. Frequency of detonation reaction is small.
** Chips in exterior coating and/or groove for retarding fin cut to bare steel do not change cook-off time.
Table 1-1.—MK 80/BLU Series Cook-Off Times
