Rockets, AT, 2.36-inch
Date Written: Oct 2007
Compiled by: Chris Guska
ROCKETS, AT, 2.36-inch.
The 2 .36-inch AT rockets are launched from the LAUNCHER, rocket, AT, MI. The launcher is diameter, equipped with hand grips, stock, firing mechanism, and sights. The firing mechanism is electrical in nature, the ignition of the rocket propelling charge being accomplished by the current from a 2 dry-cell battery in the stock. The launcher may be fired from the shoulder. There is no recoil, since propulsion of the rocket is by jet action of the propelling gases. The range of the rockets ranges from 200 to 300 yards as an optimum, although longer ranges can be obtained. The muzzle velocity is about 300 feet per second. Two types of rocket are provided; namely, high-explosive and practice.
ROCKET, AT, 2.36-inch, M6 (fig. 101). This rocket is a high- explosive projectile for use against tanks. It is long and weighs 3 1/2 pounds. The rocket consists of three principal parts: the high-explosive head, the stabilizer tube, and the fin assembly.
The head consists of metal parts which are similar in function to the parts of the AT grenade head. These parts are the ogive and the body. The bursting charge is similar, both in that it is a "hollow" or a "shaped charge," and also in its composition which is mainly 50/50 pentolite with a 10/90 pentolite booster surround. It is, however, a heavier charge, weighing approximately 1/2 pound.
The stabilizer tube consists of two principal parts: the fuze body, which threads into the union and contains the fuze mechanism, and the powder tube to which the fuze body is permanently joined, and which contains the propellent charge.
The fuze is similar in all its components to that of the AT grenade. It is, however, of heavier construction, as is the entire rocket, and contains heavier booster and detonator charges. The parts of the fuze are a spring restrained striker; a detonator of priming mixture, lead azide, and tetryl; and a booster of tetryl. The striker is held in the unarmed position prior to loading into the launcher, by a safety pin which engages an annular groove in the striker as it passes through opposed holes in the fuze body. The safety pin clips to the stabilizer tube and must be removed prior to firing of the rocket.
The powder tube or remainder of the stabilizer tube in this case serves as a housing for the propellent powder and an electric safety match or squib. The propellent powder is a monoperforated ballistite type formed into rather long grains. The electric safety match with an igniting charge of black powder is located at the upper end of the powder tube. Two contact wires pass down through the powder tube and out through the nozzle portion of the fin assembly.
The fin assembly consists of three parts : the nozzle, which is a venturi tube; the trap, which is a spider ring closing the nozzle opening above the venturi and holding the propellent powder in place; and finally, the fins themselves. The fins are six metal blades, each spot-welded to the outer surface of the nozzle at two points. Each blade is notched at a point opposite the lower extremity of the nozzle. These notches are unpainted and one of them serves as a contact for the electric safety match, one ignition wire being soldered to it. The other contact is made by means of an insulated (with a fiber strip) brass contact ring encircling the ogive. A brass connector strip runs from the end of the body to this ring. To the end of the connector strip is soldered the other ignition wire from the electric safety match. This ignition wire is taped to the stabilizer tube midway between fins and body.
Function. The safety pin is removed and the rocket inserted into the rear opening of the launcher. It is held in place by a safety catch. Firing is accomplished by establishing an electric circuit between rocket and launcher. This causes ignition of the electric safety match, the black powder ignites, and the propellent powder gases issue through the nozzle, the venturi serving to increase their velocity. This back blast serves to propel the rocket forward. There is no recoil and the back blast should not affect the firer since the powder is designed to be completely burned within the launcher. On impact with the target the striker, due to inertia, drives forward overcoming its restraining spring. It strikes and causes detonation of a detonator of priming mixture, lead azide, and tetryl, which in turn carries detonation of a tetryl booster, a 10/90 pentolite booster surround, and a 50/50 pentolite bursting charge.
Effect= The rocket has effect against various targets as follows:
1. Armor plate. Penetration slightly in excess of 3 inches of homogeneous steel armour plate at all ranges and at angles of impact as low as 60 degrees from normal. A hole, roughly cylindrical and about 1 inch in diameter, is blown through the plate, the force exerted by the detonation being of such high order that the metal of the armor plate is raised to a state of incandescence, and exits from the back of the plate in a spray of several hundred particles. Such a spray is cone-shaped with its angle of opening about 90 degrees. This spray exerts antipersonnel effect to a distance of 30 yards and usually causes explosion of ammunition it strikes.
2. Masonry. Penetration of brick walls and rock masonry not over 8 inches in thickness is accomplished with a burst having a powerful blast effect.
3. Structural steel. Shattering effect against cast steels and such materials as girders and railroad rails. Effect against a motor block causes extensive damage, in most cases irreparable.
4. Wood. Penetration of up to 9 inches of pine timber, caused by its blast action. Less than 1 inch of wood ordinarily will not cause detonation.
5. Water. Water will not cause detonation of the rocket bursting charge.
6. Soil. Impact with the ground will not ordinarily cause detonation except at ranges in excess of 300 yards. The trajectory is sufficiently flat to cause the rocket to ricochet at shorter ranges without detonating. At ranges from 300 yards to 650 yards, the extreme range, impact usually does cause detonation except in very soft soil such as mud. Bursts against the ground have much of the blast effect and all of the appearance of 75-mm H.E. shell. However, it will be under the
most exceptional circumstances that this type of rocket will ever be employed against personnel in the open.
Uses. The primary use of the rocket is of course against tanks, it being highly effective against all known types of medium tanks. It, however, has secondary uses as follows:
1. Antitank mine. The rocket is placed, nose up, in a hole in the ground about 2 feet deep, properly placed to achieve the desired effect. It is fired electrically by attaching the ends of two wires to the rocket ignition wires, one to the brass contact ring on the ogive, the other to the fins. Ordinary twisted field telephone wire and the dry-cell battery from the launcher suffice for this purpose. The rocket may be placed in a road bed or set horizontally into the side of a cut or bank.
2. Demolition. The rocket may be used for destruction of railroad rails, structural steel, disabled armored vehicles, and various types of material. It may be placed in or near the object to be destroyed, allowance being made for about a foot of travel before impact. Ignition is accomplished as in the antitank mine use.
3. Booby traps. When used for this purpose; the rocket should be sited to strike a hard surface such as masonry or heavy timbers to obtain maximum effect of the blast. The ignition would be accomplished as above with a trip wire or similar device to make contact.
ROCKET, Practice; 2.36-inch, M7. This rocket is similar in shape, size, and weight to the high-explosive type. However, it is provided with only a propellent charge, the head being inert. No
fuze is provided. The end of the stabilizer tube is extended to counterweight the head and make the ballistics of this rocket similar to that of the H.E. type. A safety pin passes through the tabilizer tube at the upper end and in order to make the detail of firing this rocket similar to that necessary in the above H.E. type. Since there is no fuze, it naturally serves no useful function. In all other respects the rocket is similar to the H.E. type. It is used for target practice only.
Painting and Marking.
The M6 Rockets (H.E.type) are painted a lustreless olive drab and stenciled in yellow, while the practice type (the M7) is painted black and stenciled in white. The stencil in each case includes the type, model, and lot number.
Each of the above types is packed 1 per fiber container, 20 containers (20 rockets) per box.
FURTHER REFERENCES: TM 9-294, TM 9-1900; FM 23-30; TC 104; SNL S-4, SNL S-9.
90th IDPG Weapons