OVERALL LENGTH

TOTAL WEIGHT

BODY LENGTH

BODY DIAMETER

WALL THICKNESS

BURSTER TUBE LENGTH

FIN LENGTH

BURSTING CHARGE (TNT)

MAXIMUM RANGE

MUZZLE VELOCITY

COLOR

MARKING

FUZING

M4, M4A1, M4A2 See page 63.

USE:

For use against ground targets such as personnel, ariplanes on the ground, light in-stallations, etc. This bomb gives good fragmentation, as well as blast effect because of the relatively high explosive charge in the head. The initial issue of the rocket went to the Army Air Forces for projection from aircraft launchers against ground targets. Inas-much as the rocket was originally designed for use from ground launchers, its use in air-craft is being discontinued in favor of Navy designed aircraft rockets.

LAUNCHERS:

From aircraft, the rockets are launched fromt the 3-tube 4.5" A.C. launcher. This consists of three tubes in a cluster under each wing, the tubes being smooth-bore plastic, approximately 10 feet in length. The rocket can be used in either single or mul-tiple-barreld ground launchers.

CONSTRUCTION:

As can be seen in the accompanying diagram, the construction of this rocket is con-siderably different from the normal type of rocket. Except for a slight tapering at the nose and the narrow base end forming the nozzle, the rocket has a constant diameter of 4.5" throughout its length. The forward end of the rocket consists of the shell, with an adapter to receive the nose fuze. The head and motor are combined into one in this rocket in the form of a tube which threads onto the shell with a central burster tube extending back into the motor. The explosive content of the rocket is contained partly in the shell and partly in the burster tube. This design furnishes much better fragmen-tation of the motor tube than in the normal type rockets with the separate head and motor. The trap assembly is a wire cage housed in the motor tube which provides a framework to hold the propellant in the proper position. This assembly consists of a trap ring, 10 trap wires, and a trap plate. Before the head is screwed into the tube, the trap assembly is slipped, trap-ring first, into the threaded end until the trap plate comes to rest on the internal bulge of the nozzle.

The fin assembly for the rocket opens and guides the rocket in flight only after the rocket has cleared the launcher. The fins of the assembly are held in place by the fin retainer, which is expeled by the blast of the escaping gas, and after clearing the laun-cher the fins snap to their outstreched position. There are six fins, all indentical.

The M8A1 involved a change in the design of the motor tube to strengthen it on the threaded end. The head of the M8 was used by machined new base threads. Tests on the M8A1 indicated that the base of the modified head was weak and a new head was designed for use with the motor of the M8A1. This rocket, the M8A2, will supersede the M8 and M8A1.

PROPELLANT:

The propellant consists of 30 sticks of ballistite. Each stick is 5" long and 7/8" in dia-meter which a 1/4" axial hole. Three sticks are placed on each trap wire, and there is sufficient clearance between the sticks and the wire to allow burning of the inner stick wall simultaneously with the burning of the outer wall. Two igniter-bag assemblies are bound on two opposite columns of the propellant, the bags assisting the ignition of the propellant by catching the flame of the igniter and in turn igniting the upper propellant sticks.

PRACTICE ROCKETS: M9, M9A1, M9A2

Similar in design and construction to the M8 series, lacking only the explosive charge and live fuze. The M4 fuze and booster may be assembled and used in the M9 as a spotting charge.