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Type 90 "Nose Initiator" - Navy

The Type 90 Nose Fuze - U.S. Designation A-1(b) - used on the Type 99 No.3 Mk.3 HE/Incendiary Bomb (70lbs).
This bomb can be configured for both ground and air-burst (When armed with a D-2 series timed tail fuze.)
Variations of this type, A-1(a) & A-1(b) are found on a few other bombs, up to the 1,800 lb class.

On release from the aircraft, the safety fork is withdrawn and the vane assembly rotates about five times, unscrewing the anvil up and off the striker spindle. (The vanes stay attached.)
On impact, the anvil slams the spindle down, breaking the shear wire causing the firing pin to strike the primer.
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