Section 1. General Section 2. Description of Various Rockets Section 3. Principal Launchers Section 4. Safety in Handling Section 5. Firing Section 6. Stowage Section 7. References
Section 1. General
- The following rockets are in general use by the amphibious forces:
- 2.36" rocket (Bazooka) M6A1 used by the infantry fired from the portable launcher M1A1. The Bazooka is also fired from a sextubal mount by PT boats.
- 4.5" BR (Barrage Rocket) are fired from LCI(G)s and LCS(L)(3)s. It may also be fired by infantry from portable launchers.
- 5.0" AR (Aircraft Rocket) are fired from LCIs and LSMs.
- 5.0" (Spin Stabilized Rocket) are fired from LCI(R)s, LSM(R)s and PTs.
- 7.2" Demolition rocket fired from an LCM. This mount known as a Woofus.
- A rocket is divided into 3 major divisions. The motor carries the propellant charge, the head carries the main explosive charge, the fuze detonates the main charge.
- The propellant charge is a grain of ballastite (a double-based smokeless powder). The ballastite burns slowly emitting gas at a uniform pressure. This gas is forced out through the nozzle (8 nozzles in the case of SSR) at the rear and by its reaction on the rocket, the rocket is propelled forward. Since there is no interaction between the rocket and the launcher, there is no recoil. This plus the fact that there is no necessity for a heavy gun barrel and mount permits the equivalent of a 5 inch gun to be mounted on the lightest landing craft.
- The ballastite is ignited by a small charge of black powder placed in the forward end of the rocket motor. The ignition charge is fired by passing a current through a platinum bridge wire. The ignition charge explodes sending a flame through the entire length
of the motor thus igniting all the exposed surface of the ballastite grain at once. Electrical contact is made either through knife edges making contact with insulated bands on the motor to which wires from the ignition charge are attached or by plugging the leads from the ignition charge directly into the firing circuit on the launcher.
Section 2. Description of Various Rockets
- The bazooka rocket, although small, has tremendous armor piercing characteristics. This is due to the fact that the explosive head works on the Monroe Principle. When the rocket hits an armor plate it burns and punches a small hole out of the plate which throws many small red hot fragments on the far side of the plate. The shrapnel is pieces of the plate itself since the rocket does not penetrate the plate. The bazooka is primarily an anti-tank weapon, the fragments ricocheting around inside the tank clean it out. It is operated by a two man team, the loader and the firer.
- The 4.5" BR is propelled by a 2.25" motor. The 4.5" head contains 61/2 lbs of TNT. The total weight of the rocket (before firing) is 30 lbs. The fragmentation effect is comparable with that of a 105 MM howitzer. The fuze used is the Mk. 137 Mod. 1 which is of the propellor arming, impact firing type. Other 4.5" heads contain 10 lbs. of FS, WP, or PWP in a 30 lb. (total weight) rocket. Normally heads, motors, and fuzes are shipped in separate containers, however sometimes the heads and motors are shipped in the same container.
- The 5.0" AR is propelled by a 3.25" motor. The head is a modified 5"/38 projectile containing 8.6 lbs of TNT. The rocket weighs 80 lbs. (before firing). Some of the heads come with base fuzes Mk. 146 or Mk. 157 (delay) installed. Nose fuzes Mk. 148 and Mk. 149 are also used. Base and/or nose fuzes may be used. The nose fuzes are of the propellor arming, point detonating type, while the base fuzes are of the pressure arming, inertia firing type. The heads, motors, and nose fuzes are shipped in separate containers.
- The 5.0" SSR is propelled by a 5.0" motor. The head carries a 10 lb. charge of TNT. The rocket weighs 50 lbs. (before firing). The spin is imparted to the rocket by the eight offset nozzles in the motor and not by any rifling on the launcher. The nozzles are offset 15° tangentially. The Mk. 30 Mod. 3 fuze used is of the centrifugally armed, point detonating type. The head and motor are packed unassembled in the same container while the fuzes are shipped in separate boxes.
- The 7.2" demolition rocket is propelled by a 2.25" motor. The head contains 33 lbs. of TNT. The rocket weighs 60 lbs. (before firing). The fuze used is the Mk. 145 which is of the propellor arming, point detonating type. This rocket is used to neutralize mines and obstacles both in shallow water and on the beach. This is the same rocket which when used with a pressure arming, impact firing fuze in anti-submarine warfare is known as a mousetrap. The heads, motors, and fuzes are shipped separately.
Section 3. Principle Launchers
- The M1A6 portable launcher is used to fire the bazooka rocket. It is fired from the shoulder similar to the rifle.
- The principle launchers for the 4.5" BR:
- Mark 1 and Mark 1 Mod. 1 (Mark 1 is port, Mk. 1 Mod. 1 is starboard). This is a 12 rail (3 wide and 4 high) "crate" type of launcher. It weighs 320 lbs. empty. The launcher is fixed in train but capable of various preset elevations. Originally designed for mounting on deck outboard of cabins on LCS(S), these are now being replaced by the Mk. 8.
- Mark 2. This is the packing box type, consisting of three rails in a wood and plastic box which also serves as the container for the assembled rockets. This launcher may be used by infantry or mounted on the deck of landing craft. It is capable of various preset elevations.
- Mark 7. (Automatic Launcher) This is a single rail automatic type of launcher. As the bottom rocket, resting on the firing rail, is fired the succeeding rounds drop by gravity onto the firing rail. The 12 rockets (the launcher's capacity) are fired in 4 seconds when the firing contact is held closed. Single shots may be fired by closing the firing contact only momentarily. The launcher is fixed in train but capable of various preset elevations. The launcher weighs 180 lbs. empty. It may be mounted on any type of landing craft.
- Mark 8. This is very similar to the Mk. 1 and Mk. 1 Mod. 1. It is used on both the port and starboard sides of the LCS(S). It is fixed on both train and elevation.
- The principle launchers for the 5.0" AR:
- Mark 30. This is a six rail (T-slot type) launcher. It consists of 3 parallel double launching rails mounted on the horizontal leg of an inverted "L" trunnion assembly. The trunnion assembly is mounted on a vertical support pipe assembly secured to the ship's deck and sides. The launcher is capable of 360° elevation in 5° steps, has 4 locked train positions 90° apart, outboard pointing dead ahead for firing, athwartships for loading, and inboard for stowing. The launcher weighs about 500 lbs.
- Mark 36. This is a 4 rail (T-slot type) launcher, fixed in train and at 45° elevation. It is mounted directly to the ship's deck.
- The principle launchers for the 5.0" SSR:
- Mark 50. This is a barrel type launcher. Each barrel has three internal guide rails spaced 120° apart about the axis of the barrel, these rails form the bearing surface of the
launcher to the rocket. The launcher consists of two rows of 4 barrels each, mounted on a horizontal supporting shaft. It has a trunnion type mount with two locked positions, outboard pointing dead ahead for firing, inboard for stowing and loading. It is capable of 360° elevation. 2 launchers are mounted on a PT boat, one starboard, one port, near the bow just forward of the charthouse. The launcher weighs 736 lbs. empty.
- Mark 51. (Automatic Launcher). This launcher is very similar to the Mk. 7 launcher used to fire 4.5" BR. The firing rail consists of three rails with the top rail offset just enough to let the rounds above drop into the firing position. The 12 rocket capacity may be fired in 412 seconds, although single shots may be fired as with the Mk. 7. The launcher weighs 165 lbs. empty.
- Mark 102 Mod. 0. The design of this launcher is based upon the components of the 40mm twin Mk 1 mount, power driven in train and elevation, with remote control. A simple double-barrelled pusher type hoist is hung from the mount and feeds the barrels when they are in vertical position. Upon receiving the two rounds the barrel assembly is hydraulically depressed into coincidence with the dummy gun, fires with a short interval between the two rounds and returns to vertical to receive another load. The rate of fire is 15 rounds per minutes per barrel, or 30 rounds per minute per mount.
- The launcher for the 7.2" demolition rocket is the Mk. 24 (Woofus). It consists of 120 rails varying in elevation from 221/2 to 45°. The launcher consists of 8 rows of 15 rails each, with catwalks separating the inboard bank of 4 rows from the outboard banks of 2 each. The launcher is jettisonable so that it may be either slung into or out of an LCM in less than 30 minutes. This permits the LCM to be used as a cargo boat when not in use as a rocket boat. The launcher weighs 12,500 lbs. empty.
Section 4. Safety in Handling
- Rocket ammunition, launchers, and firing must be treated with the particular care of a new weapon; and in order to get the maximum performance out of it, personnel responsible must make a thorough study of applicable references listed at the end of this chapter. The following comments are to be considered as supplementary to the above publications.
- In general, ammunition must be given the customary care in handling and stowage. The rocket head is the most stable. The rocket motor must not be subjected to elevated temperatures, and must never be fired while at elevated temperatures. The rocket fuzes must be given particular care in handling and stowage, and careful inspection and treatment prior to firing.
- Because most rocket launchers are light and made of thin sheet metal, they are subject to being bent or misaligned by careless treatment. There is a tendency to lean on them, sit on them, etc., which must be guarded against. All rails, troughs, tubes, etc., must be straight and true to prevent serious accidents in firing. Any moving parts must operate freely. All electrical circuits must be thoroughly water-proofed and constantly checked.
- Rocket ammunition comes in three divisions and should be stowed as such, although it is permissable to stow motors and heads in the same magazine, provided they are not assembled. Fuzes must be stowed in separate magazines. An unassembled motor while still a fire hazard is non-propulsive.
- Rockets should be assembled only prior to firing. It is permissable to assemble a number of rockets if it is anticipated that the firing rate will be greater than the assembly rate. An assembled rocket is more of a hazard than an unassembled rocket, but under battle conditions it may be necessary to forego the precaution of having the rockets unassembled. The assembled rocket must have the shorting clip on the motor and the safety pin or safe setting on the fuze.
- A responsible officer familiar with rockets must take charge of any rocket firing. If the number of launchers on any given ship is large, some responsible man must be in charge of each group of launchers. The rocket officer must be certain that the following is done.
- Check to see that the launchers are mounted securely and that the line of fire is clear of all stanchions. The area of the blast must be free from inflammable material, hoses, fenders, etc. If using automatic launchers insure that moving parts, reel gate, etc., work smoothly and that all sliding surfaces are free from obstructions.
- Never test the firing circuits with rockets in the launchers[. S]liding the rockets forward of the knife edges or not having the rocket plugged in is not enough. All rockets must be removed from the launcher while testing. Firing circuits must be tested at the launcher just before loading. There must be voltage at the proper contact when the proper firing contact is closed and at no other time.
- Precautions should have been taken that the rockets, (especially the motors) have been stowed in the proper temperature. To assemble the rocket the head and motor must be screwed tightly together with a good hand thrust. The shipping plug must be removed from the forward end of the body if a nose fuze is to be used; a check must be made to be sure the booster is in place and the fuze screwed in. The fuze must be examined before insertion to make certain it is unarmed and in working order and inserted with care so that it will not be damaged.
The motor shorting clip and the fuze safety should not be removed until immediately before loading into the launcher.
- Loading procedure:
- Check the firing circuit.
- Clear all unnecessary personnel from the launcher area, especially in front of and behind the launcher.
- Be sure the circuit is off (the rocket officer is responsible for this) remove the safety plug and hold it where the men loading can see it.
- Check the circuit at the launcher to make certain the circuit is dead -- in combat condition this step may be omitted.
- Pass ammunition to launcher, removing shorting clip at launcher (unless using ARs) just prior to placing rocket in launcher. Retain shorting clip in case of misfire. If using SSR it will be necessary to set fuze at launcher just prior to placing rocket in launcher.
- Remove safety pin from fuze. If using fuze which requires an arming wire secure arming wire before removing safety pin. Retain safety pin.
- If using launcher that has different loading and firing positions swing launcher into firing position.
- If using AR remove shorting clip and plug rocket into receptacle on launcher.
- Retire all personnel from danger zones, ahead of and behind launchers.
- Replace safety plug and turn on all switches in firing circuit only after heading toward target.
Section 5. Firing
- There are two danger areas surrounding any rocket launcher. One in front of it and the other behind it. The rocket goes one way, the blast the other. Both must be clear before firing, and the firing officer must insure himself of this.
- When on practice or test run:
- Make several attempts to fire the rocket.
- Remove safety plug and turn all switches off.
- Wait 10 minutes prior to inspecting launcher.
- * Approach launcher from the side. Check to see if nose fuze is unarmed. If it is, proceed as follows:
- If using automatic launcher, remove rounds above misfire,
fire, replacing shoring clips or bands, and making fuzes safe by setting on safe or replacing safety pin.
- Visually try to see what caused the misfire.
- Remove misfire, replacing shorting clip and safety pin.
- Examine rocket visually to see if rocket was defective.
- Toss rocket overboard fuze up.
- Check firing circuit.
NOTE: * If fuze was armed, carefully tape the propellor so that it can not turn, proceed as above lowering the rocket into deep water, fuze up, very gently.
- If under battle conditions and making firing run, attempt to fire misfire while firing the other rockets. Do not attempt to remove misfire.
- If under battle conditions but maneuvering to make another firing run:
- Remove safety plug and turn all switches off.
- If using automatic launcher, remove rockets above misfire setting them by the launcher for immediate reloading. (If any rounds have armed fuzes, tape the propellor so that it can not turn and dispose of the rocket by gently lowering it over the side, fuze up.) Replace shorting clip before lowering over the side.
- Remove misfire replacing shorting clip and safety pin. If armed, treat as above.
- Toss rocket overboard, fuze up.
- Range table of the various rockets fired from a single shore-mounted launcher at 45° quadrant elevation (maximum range); 70° temp.:
Rocket Mean Range Range Dispersion Lateral Dispersion 4.5" BR 1120 yds. 58 yds. 84 yds. 5.0" AR 4000 yds. 480 yds. 35 mils. left or right 5.0" SSR* 5250 yds. 300 yds. 20 mils. left or right 7.2" DR 300 yds. --- ---
50% of the rockets fired will land in a rectangle one dimension of which is the range dispersion, by the other the lateral dispersion, i.e. 50% of the 4.5" BRs fired at 45° QE will land in an area 84 yds. wide by 58 yds. deep, the center of this area will be 1120 yds. in front of the launcher.
NOTE: *At 45° QE the SSR has a right drift of 50 miles. Within the safe firing limits an increase in temperature increases both the range and dispersion.
- The range of the rockets may be decreased by decreasing the QE. Because of the poorer stability of rockets at low angle fire it is not recommended that the rockets be fired at lower QEs than 30° (the exceptions to this are the SSRs mounted on PTs and the Bazooka).
- The inaccuracies in both range and dispersion are increased by the roll, pitch, and yaw of the firing ship. For this reason the firing officer should make every effort to fire when the ship is on even keel, pointing toward the target.
- Whenever the target is visible the firing ship should fire ranging shots until on target, before letting go with his salvo or prescribed rate of fire. The ranging shots should be started well out so that the ship may work into position without having to turn around and make another approach. Of course when the target is not visible other means must be used to get on target.
Section 6. Stowage
- General Stowage. In general stowage requirements for smokeless powder are applicable to rocket motor stowage. High explosive rocket heads should be stowed in accordance with the regulations prescribed for stowing HE filled projectiles.
- Stowage temperature should be maintained below 90°F. if practicable, but stowage up to 100°F is not considered hazardous. Any prolonged stowage above 100°F. is considered hazardous, and positive steps should be taken to prevent this condition.
- It is of utmost importance that naked lights, matches, or other flame-producing apparatus never be allowed in the vicinity of rocket stowages.
- The rocket motor is fired electrically and should be stowed away from sources of electricity and from strong radio transmitters.
- Motors are non-propulsive until bodies are screwed on, but are still a highly dangerous fire hazard if ignited.
- Magazines in which these rockets are stowed should be fitted out with a magazine hand lantern and a temperature board for mounting maximum and minimum thermometer and temperature card.
- If separate stowage is not provided for rocket motors and heads, the crated motors and heads may be stowed in the same magazine. Fuzes should be stowed in a specially designated fuze locker or magazine. Fuzes should never be stowed in a magazine with rocket heads or motors, ammunition, or pyrotechnics.
- White phosphorous ignites spontaneously on contact with air but may be extinguished with water or carbon dioxide. Because of this hazard WP-loaded ammunition should be stowed separately from other types of ammunition and from pyrotechnics. White phosphorous will melt if subjected to temperatures above 120° F. and has a greater tendency to leak from the rocket
bodies at high temperatures. WP rocket bodies may be stowed below decks in spaces which may be completely flooded, which contain no other ammunition, and in which the temperature does not exceed 90°F.
Section 7. References
- Bazooka Rockets.
War Department Technical Manual TM9-294. Subject: Launcher, Rocket AT, M1, Date 21 Oct 1942 (Restricted).
OP 1136, 2.36" Sextuple Rocket Launcher Mk. 1 (under preparation).
- 4.5" Barrage Rockets.
OP 1003. Subject: 4.5" Rocket Launchers Mks. 1 and 8. (under revision).
OP 1017 of 7 August 1943. Subject: Projector Charge fuses (Restricted).
OP 1111. Subject: 4.5" Rocket Ammunition. (under preparation).
OP 1127. Subject: Rocket Launcher Mk. 2 Mod. 1. -- Description and Instructions for use. (under preparation).
OP 1128 of 15 March 1944. Subject: 4.5" Rocket Launcher Mk. 4 -- Description and Instructions for Use. (Restricted).
OP 1131 of 17 July 1944. Subject: 4.5" Rocket Launcher Mk. 1 (Experimental). (Restricted).
QP 1132. Subject: 4.5" Rocket Launcher Cart Mk. 1. (under preparation).
CIT JBC 10.6 -- Use, of 4.5" Barrage Rockets.
CIT JBC 16 -- Description and Instructions for Use CIT-Type 8 Mod. 1 Launcher for 4.5" Barrage Rocket.
CIT JBC 19 -- Ammunition Manual for 4.5" Rocket (1100 yd.).
CIT JEC 11.2 -- Installation and Use of Barrage Rocket Projectors for Tank Lighters.
CIT JEC 13 -- Description and Instructions for Use of CIT -- CIT PMC 2.56 -- Rockets for Ground or Surface Use.
- 5.0" Aircraft Rockets.
OP 1135 (Preliminary) of 10 November 1944. Subject: Rocket Launcher Mk. 30 Mod. 0. (Restricted).
OP 1176. Subject: Range Table for 3.5" and 5.0" Aircraft Rockets and Aircraft Launchers Mk. 4 and Mk. 5 (under preparation).
OP 1318 (Preliminary) of 14 November 1944. Subject: Rocket Launcher Mk. 36 Mo. 9. (Restricted).
CIT JDC 46 -- Design for a Cruciform Charge for the 3.5" Rocket Motor.
CIT JEC 17 -- Description and Instructions for use of CIT-Type 31C (Shipboard) Launcher.
- 5.0" Spin Stabilized Rockets.
CIT JEC 20 -- Use of Rocket Launcher Mk. 51 Mo. 0. (Twelve Round Automatic for 5.0" Spin Stabilized Rockets).
CIT OBC 41.1 -- 3.5" and 5.0" Spin-Stabilized Rockets.
- 7.2" Demolition Rocket.
OP 1168. Subject: 7.2" Rocket Launcher Mk. 25 (21 rail DUKW, CIT Type 7 Mo. 1) (under preparation).
OP 1173. Subject: 7.2" Rocket Launcher Mk. 24. (under preparation).
- Rockets General.
OP 1133. Subject: 3.25" Rocket Launcher (target) Mk. 1 and Mk. 1 No. 1. (under preparation).
OP 1175. Subject: Rocket Targets, Including Suggestions for Gunnery and Tactical training. (under preparation).
NavOrd O.D. 5368 of 22 April 1944. Rocket and Projector Charge Ammunition Assemblies. (Restricted).
CIT JMC 2.2 -- An Introduction to the Study of Rockets.
CIT JNC 10 -- Gunnery and Tactical Training with Rockets.
CIT UMC 42 -- Service Rockets, Fuzes and Launchers. (Supplement thereto).
TM 9-390 -- 4.5 Inch Artillery Rocket Launcher T35 and 4.5 Inch H.E. Rocket M9.
TM 9-395 -- 4.5 Inch Rocket Material.
NOTE: Publications starting with CIT are published by Office of Scientific Research and Development, National Defense Research Committee, California Institute of Technology.
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