Type 4 No. 25 Mk 29 was in the process of being developed at the end of the war to take the place of the No. 25 Mk 3 bombs as a weapon for use against large bomber for-mations. It was designed either to dropped in the same manner as the Mk 3 bombs, or to be detonated in the plane by the pilot. The bomb incorporates a larger explosive charge, and smaller quantity of incendiary shrapnel, than do the Mk 3 bombs of the same size.

The nose section of the bomb is conical in shape, and is filled with a wooden block ex-cept for a central channel filled with explosive leading into the main charge of the bomb. An adapter is supplied at the nose to receive the type 3 electric gaine.

The barrel of the bomb is cylindrical in shape, and is filled with incendiary shrapnel of the white phosporus filled steel pipe type. A central burster charge of high explosive is sur-rounded by the incendiary shrapnel.

The conical tail section is filled with a central burster charge surrounded by the same type of incendiary shrapnel as is found in the barrel of the bomb. An adapter is provided at the apex of the tail cone to receive the type 99 Mk 3 tail fuze D-2 (a), without cen-trifugal arming. Tail fins are standard Navy design without rotational offset, such as is found in the Mk 3 bombs.

The bomb is fuzed in the nose with the type 3 electric gaine fitted with a cable which leads into a firing switch in the cockpit of the airplane. It is to be used when the pilot desires to fire the bomb in the airplane in a suicide attack on bomber formations.

The tail fuze is a type 99 Mk 3 without centrifugal arming. It is to be used when the bomb is dropped in an air to air bombing attack.

This bomb had not gone into production at the end of the war, but was considered by the Japanese to be a practical weapon for defence against heavy bombers.

The data on this bomb is the result of incomplete investigation, and must be considered as specific, accurate information.

Figure 67 - Type 4 No. 25 Mk 29 Bomb.