This aircraft-laid, moored, contact mine bears a resemblance to the U.S. Mine Mark 10, Mod. 1. The mine case is a cylinder that floats vertically in the water when moored. It has four electrochemical horns equipeed with brackets that are extended outward above the top of case by spring pressure.

The physical characteristics of the mine are as follows:

Case

Shape – Cylindrical, 24" in diameter and 52".5 long.

Material – Steel.

Total Weight – 600 lbs.

Charge – 240 lbs. Type 98 explosive.

External Fittings

Horns – Four, electrochemical, equally spaced around the top of the case. Each horn is equipped with a spring-loaded steel extension.

Detonator Housing – On the side of the case near the bottom.

Booster Release Mechanism – In an opening on the case 180° from the detonator housing.

Base Plate – On the bottom of the case, equipped with a mooring lever controlled by a solube-plug mechanism; and a hydrostat assembly.

Operation

The anchor for this mine has not been recovered, therefore, its operation is not known. The mine is laid with a parachute from aircraft; some time after laying the spring extensions on the horns are released and snap outward. Hydrostatic pressure release the booster, which is driven across the booster tube under spring pressure, housing it over the detonator. Dissolution of the sluble plug in the base plate allows mooring tension to operate the mooring lever, arming the mine.

The mine fires when one of its horns is bent sufficiently to break a glass vial allowing electrolyte to run into a battery, generating sufficient current to fire the detonator.

Safety Precautions

A safety switch is designed to disarm the mine when the mooring cable breaks or is cut, but this feature is not reliable. Therefore if found adrift, or on the beach, it should be considered dangerous.

Figure 26 – Two views of the type JJ mine.