Description
This is an Navy mechanical impact tail fuze. It is used in the 250 kg and 500 kg bombs. The fuze is steel except for a brass locking ring, locking collar, and arming spindle. This fuze can be found with nose fuzes A-3(a), A-3(b), A-3(d), A-3(f).
The fuze body houses the safety collar, the striker, the arming spindle and the spring. Six spanner holes are found in both the body and the locking ring. The arming assembly consists of a long reach rod connecting the arming spindle and the vanes. The lower end of the spindle screws through the top of the fuze body and the safety collar into the striker.
Slight variations of the B-2(a) which have been recovered are: 1) fuze body and locking ring made of zinc-plated steel alloy; 2) fuze body made of unplated steel, locking ring made of brass, body shoulders are straight rather than sloping and has two locating pins located 180° apart. This latter fuze with a longer reach rod has the Japanese designation of Type 2 No. 50 Ordinary Bomb Model 1 Tail Fuze. Operation is the same as the Type 99 No. 25 Tail Fuze.
Functioning
On release from the plane, the vanes rotate, unscrewing the arming spindle from the striker. On impact, the striker moves against the action of the spring and pierces the primer in the gaine to set off the exploder system.
Hazardous Components
The standard Japanese gaine is employed.
Physical Data
Length, overall - 4.5 in, 114.3 mm (without the arming spindle extension)
Width, overall - 2.55 in, 64.8 mm
Vane span - 4.69 in, 119.1 mm
See Also
Nose, A-3(a), Type 97 Mk 2 Model 2
Nose, A-3(d), Type 97 Mk 2 Model 1
Nose, A-3(f), for Type 2 No. 50 Ordinary Model 1
Source(s)
OP 1667, Japanese Explosive Ordnance, Volume 1 (1946)
USNBD - Japanese Bombs & Fuzes (1944)
TM-E9-1984, Enemy Bombs and Fuzes, Section VII, Japanese Fuzes (1942)
