OVERALL LENGTH

TOTAL WEIGHT

HEAD DIAMETER

HEAD LENGTH

HEAD WEIGHT

MOTOR LENGTH

MOTOR DIAMETER

WIDTH OF TAIL FINS

LENGTH OF TAIL FINS

FUZES

GENERAL:

The "Window Rocket" is designed to be fired from Naval vessels equipped with a mo-dification of the present ship-board launcher. The round carries a payload of paper-coated metal foil strips which are scattered in the air by a delayed-action charge. The pay-load is ejected at an altitude of 1200 ft. and range of 2000 yds at 45° elevation.

The purpose of the rocket is to interrupt enemy Radar, providing a screen behind which our ships may approach or maneuver undetected, or to provide a false target for enemy Radar.

DESCRIPTION:

The "Window Rocket" consists of the complete round assembly No. 3.55P010 (3.5" Rocket Head, Mk 10-0 and 3.25" Motor Mk 12-0). The Mk 12-0 Motor uses the Mk 7 Mod 1, (solventless extruded cylindrical) propellant grain, weighing 2.80 lbs.

The Rocket head Mk 10-0 contains a 3.5" Rocket Head load Mk 1 or Mk 2 which is housed in a split steel ejection liner, a closure adapter on the after end, an obturator cup for sealing the front end, and a wooden ogive cap held in by three aluminum rivets. The closure adapter welded to the after end carries a copper diaphragm plate with a firing pin and also serves as a chamber for the Cal. 32 blank cartridge which ignites the fuze. The Mk 134 fuze consists of a plastic case containing a length of Ensign Bickford fuse and an ejector charge of black powder (20 grams).

The head load, Mk 1, is approximately 6700 paper-coated strips of aluminum foil, 0.003" thick, 3/16" wide, and of varying lengths, housed in a wooden case approxima-tely 2-55/64" diameter and 15 in. long. This load is enclosed in two metal half cylinders for protection during expulsion.

OPERATION:

When the rocket is fired, gas pressure blows out the forward closure disc and exerts force on the diaphragm plate in the base of the motor adapter. The diaphragm collaps-es and the firing pin is forced into the primer, firing the blank cartridge. The flash from the cartridge ignites the fuze which burns 15 seconds and then ignites the black pow-der ejector charge. The firing of the ejector charge shears the rivets holding the woo-den ogive cap, and pushes the load forward out of the head. The metal strips are then dispersed.

REMARKS:

A modified design is the 3.5" Rocket Assembly No. 3.55PO28, consisting of the 3.25" Motor Mk 14 and 3.5" head Mk 14. This motor is designed like the 3.25" motor Mk 7, and the head differs from the Mk 10 head primarily in having a hollow steel ogive instead of a wooden one. See details of motor and head on page 25.