H.E. SHELLS

OVERALL LENGTH

DIAMETER

TOTAL WEIGHT

EXPLOSIVE

EXPLOSIVE WEIGHT

FUZING

ROCKET MOTORS

OVERALL LENGTH

DIAMETER

WIDTH OF FINS

TOTAL WEIGHT

PROPELLANT

tubular

tubular

PROPELLANT WEIGHT

BURNING TIME - 60° F

1.6 secs.

2.25 secs.

GENERAL:

These rockets are designed for anti-aircraft purposes, and thus are always fitted with some type of time (aerial burst) fuzing.

DESCRIPTION:

Shell, H.E., No. 1 Mk I: This shell consists of a steel cylinder, reduced in diameter at the base and threaded externally to screw into the shell ring of the rocket motor. The foreward end of the shell is threaded internally to receive the base of the No. 731 fuze or the adapter ring employed with the No. 700 fuze. Held in the nose fuze cavity by a locking ring is an exploder container with a booster charge consisting of a 26 dram C.E. (tetryl) pellet and a 4 ounce T.N.T. pellet separated by a felt disc. A gaine, or booster, No. 13 Mk I is employed with fuzes used in this shell.

Shell, H.E., No. 2 Mk I: This shell consists of a light steel ogive struck with a 30 inch radius. The after part of the shell body is reduced in diameter and threaded externally to screw into the shell ring of the rocket motor. An internally threaded fuze adapter is welded to the foreword end of the shell body. A cardboard exploder container is inser-ted into the main explosive filler beneath the fuze adpater and contains a 12 dram C.E. (tetryl) booster pellet.

Tail Propelling, U 3", Mks I & II: These motors are identical except that the Mk I contains a tubular grain, while the Mk II grain is cruciform in shape. The motor body consists of a steel cylinder, slotted at the tail end to receive the four tail fins. A shell ring, fitted in the head end of the body, is internally threaded to receive the base of the shell, and has eight holes to correspond with those in the motor body. Locking pins, flanged on their inner ends, are inserted through these holes and are retained in posi-tion by two circular band springs. A copper or cadmium plated steel obturator is placed in the rear of the shell ring and is separated from the propellant grain by an cardboard disc and two cardboard washers. The propellant grain is castellated at the foreward end to receive the igniter, and a washer of dummy cordite attached to the base of the grain bears against the ring of the grid. Spacing discs and tabs are attached to the ex-terior of the cordite grain by a special cement. The igniter consists of a 10 gram charge of magnesium with an electric squib enclosed in a paper tube. The insulated electric leads pass through the central channel of the cordite grain to the contacts at the after end of the motor body. The tail obturator, positioned between the grind and venturi tube, is made in the form of a steel cup with a central perforation. The steel venturi tube is attached to the motor body by screws and welding and contains a small bag of silica gel as a moisture-proofing measure. The leads from the igniter are connected to the four contacts around the outside of the motor body, so positioned that they make contact with the knife edges on the launcher regardless of the angle at which the roc-ket is loaded.

Though generally fin-stabilized, these rockets are sometimes fitted with narrow 3/4" fins, stabilization being obtained by spiralling the rails on the inside of the launcher bar-rel.

REMARKS:

(1) The shells are painted buff overall and carry a stencilled ring of red crosses 1/2" wide and 1" behind the foreward end of the shell body. A green band, upon which are stencilled in black letters "T.N.T.", is located 4.5" behind the foreward end of the shell. Complete identification, filling, and manufacturing information is stencilled in black on the shell body between these painted rings.

(2) Proposed new nomenclature for the rocket motors is as follows:

Old Nomenclature

Tail Propelling, Rocket, 3", Mk I

Tail Propelling, Rocket, 3", Mk II

Motor, Rocket, 3", No. 2 Mk I

(3) Although originally designed for assembly with these motors, the No. 2 Mk I H.E. Shell has never been so emlpyed.