OVERALL LENGTH

BODY LENGTH

BODY DIAMETER

BODY WEIGHT

FILLER WEIGHT (TNT)

WALL THICKNESS

MOTOR LENGTH

MOTOR DIAMETER

MOTOR WEIGHT

TAIL WIDTH

COLOR

TOTAL WEIGHT

65 lbs.

TARGET:

For use by patrol vessels against submarines. The most comon installation consists of two 4-rail launcher, Mk 20 with a fixed elevation of 48° mounted on the fore deck with firing controlled from the bridge.

FUZING:

The Mk 131 and Mk 140 fuzes are replaced by the Mk 156.

COMPLETE ROUND ASSEMBLY:

At present some nine models of the 7.2" Rocket for shipboard use are in service or contemplated. The most common unit now is service is the Mk 6, for which the above data is given. Following are the service assembly rounds which are being used and will be used.*

Complete Round

Body

Filling

Motor

Grain

Fuze

Mk 6

Mk 3

Mk 7

Mk 3

Mk 8

Mk 3

Mk 9

Mk 10

Mk 10

Mk 10

Mk 15

7.2" Mk 4

TNT

2.25" Mk 3

Mk 3

Mk 140 - Mk 156

The most common unit now in service is the Mk 6.

* In addition to the service rounds included in the table, there are the 7.2" Rockets Mks 106 and 109 filled with plaster for target practice, and the Mk 206 and 209 filled with plaster for drill.

BODY CONSTRUCTION:

The projectile consists of a flat nosed body with a concial tail fairing and parallel sides amidships. The adapter and fuze thread into the nose and the motor unit threads into the base of the unit.

MOTOR:

The motor unit contains a long simple pellet of smokeless powder which, when ingit-ed by a black powder primer fired by an electric squib, burns at a pressure of 1000 to 2000 lbs. per sq. in. The gases are forced out aft through the nozzle in the rear end of the motor tube. The propulsion is completely independent of any agent which would introduce a recoil problem. The burning continues for from .2 to .7 of a second during which time the missile travels about 30 feet, at which point propulsion ceases and the projectile is free in flight. This projector charge is intended for use on the Mk 20, 21 or 22 7.2" Rocket Launchers.

TAIL CONSTRUCTION:

Steel tube attached to body by a threaded joint; tail fins with two circular drums attached to the after end to give stabilized trajectory. The vanes have a 10 degree twist to give a slow rotation and prevent ruddering. The two vanes support drums also act as contact rings, the wiring from the electric squib passing from the primer aft to the two rings which as firing contacts.

REMARKRS:

1. When Torpex is used, the weight is increased by approximately 2.5 lbs.

2. The 2.5" (sub-caliber) Rocket, consisting of the 1.25" Mk 1 motor and 2.5" Mk 1 head, is a miniature of the regular rocket and is used in practice. The motor, fabricated of steel, contains a single tubular powder grain, an igniter, and lead wires. The tail fins, supported by a shroud, are offset 5 degrees to impart some rotation to the round with the object of improving underwater travel. The Mk 1 head has a cavity for a shot gun shell; the Mk 1 Mod 2 head is solid.