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| Japanese Explosive Ordnance – Army Ammunition – Navy Ammunition |
| Chapter 5 - Section 1 |
| NAVY PROJECTILES |
| 12-cm (120-mm) (4.7-Inch) Illuminating Projectile |
| Weight of filled projectile: 44 pounds. |
| Weight of empty projectile: No data. |
| Weight stamped on rotating band: No data. |
| Length of projectile (without fuze): 13 13/16 inches. |
| Diameter at bourrelet: 4 11/16 inches (119 mm). |
| Distance from base to rotating band: No data. |
| Width of rotating band: 1 15/16 inches. |
| Radius of ogive: No data. |
| Filling: Expelling charge (black powder): 0.5 ounce. |
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Illuminating: These are 10 pyrotechnic cylinders arranged in two layers of 5 cylinders each. A cylinder is formed of a though waxed cardboard tube containing a silver pyro-technic mixture in the center and a reddish-brown pyrotechnic mixture in either end. |
| Weight (each cylinder): 5.4 ounce. |
| Analysis of illuminant: |
| Barium nitrate: 35.6 percent. |
| Potassium nitrate: 10.4 percent. |
| Magnesium: 38.0 percent. |
| Wax: 13.0 percent. |
| Carbon: 0.8 percent. |
| Sulphur: 1.3 percent. |
| Analysis of first compound: |
| Potassium nitrate: 63.2 percent. |
| Iron oxide: 3.8 percent. |
| Aluminum oxide: 1.1 percent. |
| Sulphur: 8.2 percent. |
| Wax: 5.5 percent. |
| Glass: 6.1 percent. |
| Carbon: 12.1 percent. |
| Cylinder metal frame: |
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This frame fills the cavity of the projectile and is positioned by studs. There are three metal discs attached to a central spindle which provides a method of functioning and serves to support the pyrotechnic increments. Arranged about the circumference of this frame are two layers of five steel wedges which position the pyrotechnic increments within the frame. |
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Fuzing: 30-second time fuze. |
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Weapons in which used: |
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Type 11-year 12-cm/45 gun. |
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Type 3-year 12-cm/45 gun. |
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Operation: When the fuze functions, the flash from the black powder magazine ignites a small black powder charge in the nose of the projectile, which in turn ignites the powder trains in the central spindle. The flash from this train ignites the powder trains in the three discs and thus the ten increments and the ejecting charge. As the cylinder is blown from the case, it shears the studs and forces the nose and body of the projectile apart. |
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Figure 389 – 12-cm Illuminating. |
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