DEPTH CHARGES

USED IN

FUNCTIONING

ARMED CONDITION

MAX. BODY DIAMETER

OVERALL LENGTH

COLOR

MAX. BODY DIAMETER

DESCRIPTION:

The depth adjuster comprisses a cylindrical body in which is housed an orifice plate containing 3 leak holes of different sizes, corresponding to firing depths of 50, 100 & 150 feet. Located on top of the orifice plate is a strainer plate and an adjuster spring which holds the strainer plate in position and the orifice plate on its seating. The orifice plate is mounted on a spindle, the lower end of which fits in a hole in the bottom of the adjuster body and is hollow and slotted to receive a safety rod. Fitted loosely on the upper end of the spindle is a spring barrel, an extension of which fits in a hole in the center of an adjuster cover. A pointer is secured to the spring barrel extension, and both extension and pointer are slotted for the use of a winding tool. A pin the the bot-tom of the spring barrel projects through the strainer plate into a hole in the orifice plate, and coupled to the bottom of the spring barrel at its lower end and to the ad-juster cover at its upper end is a torsion spring which tends to rotate the orifice plate and the pointer in a clockwise direction.

The adjuster body is closed by the adjuster cover. Marked on the cover is the word "SAFE", and the depth setting numbers 50, 100, and 150; at the side of "SAFE" is a hole to receive the safety stud, and beside each number a hole for a stop pin. Three inlet holes in the cover allow water to enter the adjuster body. In the safety position the pointer is secured to the safety stud by a safety clip.

In the bottom of the adjuster body is a hole which allows water to enter the primer tube of a depth charge when any particular leak hole in the orifice plate is in line with it, but it is blanked by a plain section of the orifice plate when the depth adjuster is set at "SAFE".

Screwed to a spigot on the bottom of the adjuster body is a safety rod guide to which is screwed the upper end of the distance tube. This tube houses a safety rod through the upper end of which is inserted a pin which engages in the slots in the ori-fice plate spindle and also with two cams formed on the spigot on the bottom of the adjuster body. When the depth adjuster is set at "SAFE", the safety rod is held in the lowered position.

The pistol comprises a cylindrical body which houses a firing mechanism. The body is closed at the upper end by a pistol cover which is screwed to the lower end of the dis-tance tube and is secured in the pistol body by a ring nut. In the pistol cover and the pistol body respectively slide an inner and outer flanged sleeve, each sleeve having a hollow stem, the stem of the outer sleeve sliding over that of the inner. Between the flanges of the sleeve is a double acting rubber diaphragm, the two discs of which are separated by a distance ring. Between each discs of the diaphragm and the distance ring is a lead foil washer to prevent adhesion. The pistol cover, pistol body, and sleeves have air vents to equalize the internal pressure. The pistol body and distance ring both have six evenly spaced holes through which is transmitted the pressure which expands the diaphragm, thereby moving the sleeves in opposite directions. The fact that the inner and outer sleeves move in opposite to operate the firing mechasnism renders the pistol inertia proof, as no shock can produce these opposed motions simultaneously. The striker slides in the stem of the inner sleeve and is held cokced by two balls, loca-ted in the inner sleeve, engaging in a groove in the striker. When the depth adjuster is set at "SAFE", the striker is prevented from moving upwards by the safety rod.

OPERATION:

On release from the plane the safety clip is pulled free by the fuze setting control link. When the depth charge becomes submerged, water enters the adjuster body and passes the strainer plate, the particular leak hole in the orifice plate, and the hole in the bottom of the adjuster body, to the primer tube where pressure is built up. While the depth charge is sinking the increased pressure is transmitted through the holes in the pistol body and distance ring to the two discs of the diaphragm, which begins to expand and move the sleeves and striker, compressing the firing spring. When the depth charge has sunk to its set depth, the two sleeves have moved through their maximum travel, and the balls are forced out into a recess formed in the stem of the outer sleeve, thereby releasing the striker, which fires the detonator.

REMARKS:

1. Some Mk X** depth charge pistols have an adjuster with holes drilled for 250, 350, and 500 feet.

2. This pistol, though no longer used for aircraft depth charges remains the standard depth charge pistol for charges dropped by surface craft.

3. An identical copy of this pistol has been developed and used by the Japanese.