Mechanical Fuzing System for Aircraft Bombs

M904 is a mechanical action nose fuze designed for use with all types of General Purpose (GP) low and high drag bombs Mk80. The fuze is armed by air pressure causing the arming vanes to rotate. Minimum airspeed of approximately 150 knots is required for arming. Arming delay time is marked in 2 s intervals from 6 to 18 sec. On impact a firing delay time is provided by delay element M9. An adaptor is required to accommodate the 2 inch fuze thread in the larger fuze wells of the Mk80. This fuze may be used for impact and impact-delay application in conjunction with tail fuze M905



A safety wire inserted in the fuze prevents the arming vane from rotating. A red tag, attached to the safety wire inserted in the fuze states that a white stripe must be visible through the inspection window at the 6 and 18 second arming setting.

An inspection window in the thumb grip just above the rotor cavity shows the rotor after it moves into the armed position. The window in the body will show red if the striker body has moved into the firing position. Either condition indicates an armed fuze.

In unarmed condition, the rotor is out of line with the rest of the explosive train. The delay or non delay element is not inserted in the fuze until it is ito be used. The empty delay element cavity acts as an interruptor to the explosive train during handling, transporting and storage.


One (1) M904 Tail Fuze packed complete with coupler drive and vane arming assembly without non delay or delay elements sealed in tubular containers. 8 Tubular containers sealed under vacuum in plastic bugs. Ten (10) Delay Elements in tubular containers sealed under vacuum in wooden boxes. Four Hundred (400) elements per wooden box. Ten (10) Non Delay Elements sealed in tubular containers sealed under vacuum in wooden boxes. Four Hundred (400) elements per wooden box. Other packing options are available upon customer request.


Thread – 2 in (50.8 mm)

Length Total – 235 mm

Mass Total – 980 g

Booster – M35, Dextrinated Lead Azide 266 mg and Tetryl 200 mg

Temperature Range – -40o C to 70o C

Arming Time – 6 to 18 s, in intervals: 6, 8, 10, 12, 14, 16,18 s

Primer – Instantaneous or Delay Elements: 0.010, 0.025, 0.050, 0.100, 0.250 s

Inspection – 2 Inspection Peep Holes

Captive Flight – 600 KTAS air speed max, 60000 ft altitude max

Release – 200 – 600 KTAS air speed, 500 – 50000 ft altitude

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