The Japanese navy produced a large number of different types of bombs, these were sub-divided into three main categories:
| Designation |
Type |
Weight |
Content weight |
Content type [1] |
Construction |
Length |
Suspension lugs |
Nose |
Tail |
Fuze |
Notes |
| No.6 |
Land Bomb |
(140 lb) 63.5 kg |
|
Picric acid or later Type 98 explosive (mod 1) |
|
|
|
Cast steel |
|
Type 2 Model 2 mod 0 or mod 1 |
Obsolete during the war. Case is similar to the Type 99 No. 6 Mk. 2[2] |
| Type 97 No.6 |
Land Bomb |
124 lb |
50 lb |
Picric acid or Type 98 explosive |
Welded and riveted 1/4 inch steel |
40 inches |
Horizontal navy type |
Cast steel |
7 7/8 inches long sheet steel |
A-3(a) |
Capable of penetrating 200 mm of reinforced concrete [2] |
| Type 2 No.6 Model 5 |
Land Bomb |
132 lb (approx) |
|
Five 7 kg high explosive bombs with bursting charge |
Sheet 1/16 inch steel |
42 inches |
Horizontal navy type |
- |
16 1/4 inches |
A-3 (a) or A-3 (b) |
|
| No.25 |
Land Bomb |
550 lb |
330 lb |
Type 98 explosive |
Welded and riveted 1/4 inch steel |
72 inches |
Horizontal navy type |
Cast steel |
36.5 inch long sheet steel |
A-3 (a), A-3 (b), C-2 (a), C-1 (a) |
Designed in 1938, production ceased early in the Second World War [2] |
| Type 98 No.25 |
Land Bomb |
532 lb |
211 lb |
Picric acid or Type 98 explosive |
Welded and riveted 1/2 inch steel |
72 inches |
Horizontal navy type |
Cast steel |
32.5 inch long sheet steel |
A-3 (a), A-3 (b), C-2 (a), C-1 (a) |
The bomb was used by Japanese forces at the Battle of Midway[3]. Designed in 1937 adopted in 1938. Capable of penetrating 400 mm of reinforced concrete. [2] |
| No.80 |
Land Bomb |
1,760 lb |
842 lb |
Picric acid or Type 98 explosive |
Welded and riveted 1/2 inch steel |
113 inches |
Horizontal, two guide studs, and carrying band |
Cast steel |
41 inch long 1/8 inch steel |
A-1 (c), B-3 (b), A-3 (d) |
The bomb was used by Japanese forces at the Battle of Midway[3]. The bomb was designed in 1937 and adopted in 1938, and will penetrate 400 mm of reinforced concrete. [2] |
| Type 99 No.25 |
Ordinary Bomb |
550 lb |
132 lb |
Type 91 explosive (Trinitroanisol) |
One piece of machine forged 3/4 inch steel |
68 inches |
Horizontal navy type |
- |
28 inch long 1/16 inch steel |
A-3 (a), A-3 (b), B-2 (a) |
Designed in 1938 and adopted in 1939, it is capable of penetrating 50 mm of armour [2]. |
| Type 2 No. 50 Model 1 |
Ordinary Bomb |
1,100 lb |
148 lb |
Cast blocks of Type 98 explosive |
One piece of machine forged steel 1 to 7.5 inches thick |
78 inches |
Horizontal, two guide studs and suspension band |
- |
39.5 inch long sheet steel |
A-3 (f), B-2 (a) |
Teardrop shaped |
| No.80 Model 1 |
Ordinary Bomb |
1,820 lb |
770 lb |
Type 91 explosive |
One piece of machine forged steel 0.75 inch thick |
111.5 inches |
Horizontal, two guide studs, and suspension band |
- |
49 inch long 5/32 inch thick steel |
A-1 (c), A-3 (c), A-3 (d), tail: B-3 (b) |
|
| No.3 Model 2 |
Ordinary Bomb |
70 lb |
? |
Picric acid [4] |
One piece of machined steel |
33 inches |
Horizontal stud on either side of the body |
- |
13.25 inches |
A-1 (a), A-3 (a) |
Teardrop shaped. Obsolete since the early stages of the war. |
| No.6 Model 2 |
Ordinary Bomb |
139 lb |
65 lb |
Picric acid |
One piece of machined steel |
42.5 inches |
Horizontal stud on either side of the body |
- |
17 inches |
A-1 (a), A-3 (a) |
Teardrop shaped. Production ceased sometime between 1940 and 1941, although they continuted to be used. [2] |
| No.25 Model 2 |
Ordinary Bomb |
557 lb |
228 lb |
Picric acid |
One piece of machined steel 5/8 inch thick |
71.5 inches |
Horizontal, navy type |
- |
27 inches |
A-3 (a), B-3 (a) |
Teardrop shaped. The bomb was used by Japanese forces at the Battle of Midway[3] |
| No.50 Model 2 |
Ordinary Bomb |
1080 lb |
457.5 lb |
Type 98 explosive |
One piece of machined steel 4 to 0.5 inches thick |
90 inches |
Horizontal, two guide studs and suspension band |
- |
33 inches |
A-3 (a), B-3 (a) |
Teardrop shaped |
| Type 99 No.6 Mk 2 |
- |
140 lb |
85 lb |
Type 98 explosive |
Cast nose plug welded to a 3/16 inch thick cylindrical body |
42 inches |
Horizontal, two guide studs and suspension band |
- |
21 inches |
A-3 (a) |
A Mod 1 version of the bomb was also produced with a cylindrical steel anti-ricochet attachment spot welded to the nose giving it a blunt profile. |
| Type 1 No.25 Mk 2 Model 1 |
- |
572 lb |
317 lb |
Type 98 explosive |
Cast nose welded to a 1/4 inch thick cylindrical body |
72 inches |
Horizontal, two guide studs and suspension band |
- |
21.5 inches followed
by a 15 inch plywood extension |
A-3 (a), B-3 (a) |
A Mod 1 version of the bomb was also produced with a cylindrical steel anti-ricochet attachment spot welded to the nose giving it a blunt profile. |
| Type 99 No.80 Mk 5 |
Armour piercing |
1,641 lb [5] |
66 lb |
Type 91 explosive |
Single piece of machined forged steel 4 inches thick at the nose and two at the tail |
95.5 inches |
Two guide studs and suspension band |
- |
43 3/8 inches |
Two B-2 (b) tail fuzes |
Tear drop shaped bomb, eight recesses around the nose could allow the fitting of a wind shield if used as a projectile. Adopted in 1941, basically a converted 40 cm AP shell, capable of penetrating 150 mm of armour. [2] |
| Type 2 No.80 Mk 5 |
Armour piercing |
1,760 lb (approx) |
100 lb (approx) |
Type 91 explosive |
Single piece of machined forged steel |
|
|
- |
|
Two B-2 (b) tail fuzes |
Intended to supersede the Type 99 No.80. Not produced in large numbers. Designed in 1939, and adopted in 1942. [2] |
| Type 3 No.150 Mk 5 |
Armour piercing |
3,300 lb (approx) |
200 lb (approx) |
Type 91 explosive |
Single piece of machined forged steel |
|
|
- |
|
Two B-2 (b) type tail fuzes |
Intended to supersede the Type 99 No.80. Not produced in large numbers. Designed in 1942 and tested in 1944, was in experimental production at the end of the war. [2] |
| Type 3 No.25 Mk 8 model 1 |
|
649 lb (approx) |
263 lb (approx) |
Type 97 explosive |
Cast steel nose, welded to cylindrical body 0.5 inches thick |
67 inches |
Horizontal type navy |
Cast steel |
27 3/8 inches long |
A-3 (a) |
|
| Type 3 No.6 Mk 23 model 1 |
|
143 lb (approx) |
50 lb (approx) |
Type 98 explosive
or Picric acid |
Cast steel nose, welded and riveted to cylindrical body 0.25 inches thick |
40.75 inches |
Normal type navy |
Cast steel with anti-riccochet cone |
18 1/2 inches long |
C-2 (a) |
|
| Type 4 No.25 Mk 29 |
Air-to-air bomb |
- |
- |
Explosive with white phosphorus filled steel pellets |
Sheet steel with wooden blocks in the nose |
- |
- |
- |
- |
D-2(a) fuze |
Under development at the end of the war to replace No.25 Mk 3 for use against bomber formations, having a larger explosive charge and less incendiary shrapnel. |
| Type 3 No.25 Mk 31 Model 1 |
Airburst |
378 lb |
175 lb |
Type 98 explosive |
Sheet steel cylinder 0.5 inches thick with blunt nose |
62 inches |
Normal navy type |
Blunt steel with flange |
32 inches |
Type 3 electric firing device B-3(a) |
Type 3 fuze triggers the bomb at a height of about 7 meters using an electro optical sensor. |
| Type 3 No.80 Mk 31 Model 1 |
Airburst |
1,584 lb |
922 lb |
Type 98 explosive cast into blocks |
Sheet steel cylinder 9/16 inches thick with blunt nose |
113 inches |
Two guide studs and a suspension band |
Blunt steel with flange |
41 inches |
Type 3 electric firing device B-3(b) |
Type 3 fuze triggers the bomb at a height of about 7 meters using an electro optical sensor. |
| Type 5 No.25 Mk 33 |
Airburst |
- |
- |
Explosive with a layer of cylindrical steel fragments |
- |
- |
- |
Rounded with plummet fuze holder |
- |
Plummet electrical fuze with backup Type 15 model 2 fuze |
The bomb uses four retarding drogue plates that are opened by an atmospheric pressure fuze to slow descent and release the all-ways plummet fuze, which is suspended by a twenty meter silk clad copper to the main bomb. When the plummet fuze touches the ground the bomb is triggered. |
The Japanese produced a number of bombs with rocket motors installed, intended for air to air use against bomber formations, or as armour piercing weapons. Only two saw service, the Type 3 No.25 Mk 4 armour piercing rocket bomb, and the Type 3 No.6 Mk.27 air-to-air rocket bomb.
The numeral approximates the order in which the fuzes were captured by the allies. Finally the lower-case letter in parentheses indicates the different but similar designs.
Where possible the original Japanese designation is given.