Bell P-39 Airacobra

Bell P-39 at 4th Air Depot in Australia

Wax is applied to an overhauled P-39 Airacobra at 4th Air Depot repair shop at Garbutt Field, Townsville, Australia in June 1943. (U.S. Air Force Photo)

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10 cm Type 98 Dual Purpose Gun

Intelligence report on the Japanese 10 cm Type 98 (1938) Dual Purpose Gun from Japanese Artillery Weapons, CINCPAC-CINCPOA, Bulletin 152-45, July 1945.


This twin mount dual purpose gun was encountered for the first time on Iwo Jima. With its high muzzle velocity and long range it is one of the Japs most powerful anti-aircraft and medium caliber coast defense weapons.

Japanese Twin 10 cm Type 98 Dual Purpose Gun WW2

Recognition is made easy by the extreme length of the barrels (65 calibers) and the two symmetrical horizontal sliding type breech blocks. Ammunition loading trays are provided on either side of the breech blocks to aid in loading. The Navy type riveted shield revolves around a steel base.

A four meter rangefinder was found with the battery on Iwo, and although no director was recovered, Types 94, 2 and 4 directors may be used with these weapons.

With the electric motor provided to facilitate elevation and traverse, a speed of over 16 feet per second for each is possible. A rate of fire (firing both barrels) of 456 rounds per hour (8 rds per minute) is allegedly possible.


Caliber        100 mm (3.93 in.)
Length of bore 65 calibers
Muzzle velocity 3,280 ft/sec.
Maximum range (horizontal) 20,400 yds.
Maximum range (vertical) 44,300 yds.
Effective range (vertical) 34,400 ft.
Rate of fire 15 rds/min.
Elevation 90 degrees
Depression 10 degrees
Weight of projectile 28.7 pounds