Monday, 5 November 2018

American Guided Missiles - Introduction & Bureau of Ordnance Missiles





American Projectiles and Explosives



Missiles





Introduction





General

One of the newest trends [c.1947] in American ordnance development, guided missiles became service items in the last months of World War II.  Guidance was applied to modified bombs, winged glide bombs, and standard aircraft, and in jet- and rocket-propelled airframes.

Guided missiles have great range, high payload capacity, and extreme accuracy; and their progress in designed has proceeded so rapidly that on only a few items has the design become standardized or "frozen".  All the missiles included here were at least in the testing stage and were being pursued as active projects at the time of writing.  Furthermore, only those missiles designed for combat or military purposes - none of the basic research items - are included; and, of these, only their ordnance components can be described in detail.


Guidance

American missiles are usually guided by remote radio control, the receiver in the missile acting through servo units to position the air foils.



Intelligence

The person controlling the flight of the missile will guide its path on the basis of information obtained visually, through a television receiver, or by ordinary radar tracking.  Some missiles have automatic guidance features, of such a nature that, once the target has been "shown" to the missile's intelligence unit, it will automatically "home on" to its destination unassisted.



Propulsion

Depending on the particular item, a missile may be powered by gravity, aircraft, engines, JATO units, rocket motors, or jet motors.



Warheads

Thus far, guided missiles have adapted standard bombs as their explosive payloads.  Fuzing of these bombs differs from the standard fuzes in that the fuzes must be made in an elbow shape, in order to fit in the fuze pockets and, at the same time, permit vane arming.



Cognizance

For the Navy, the Bureau of Ordnance and the Bureau of Aeronautics are developing guided missiles; for the Army, the Air Forces are in charge of the program.






Bureau of Ordnance Missiles




1,200-pound "Dove" Bomb Mk 64 (Air-to-Surface Missile)


Overall length: 84.5 inches
Overall diameter: 18.75 inches

Weight of intelligence units and special tail: 183 pounds
Warhead (1,000-pound G.P. Bomb AN-M65): 975 pounds

Total weight: 1,160 pounds



General: The Bomb Mk 64 is an experimental heat-homing bomb, consisting of a detecting, computing, and guiding mechanism housed in a nose attachment fitted on the 1,000-pound G.P. Bomb AN-M65.  It is designed for attack on maneuvering targets and is effectively employed in both high-angle and dive-bombing runs against objects which have sufficient thermal contrast to their background.

"Dove" is designed to fit the normal plane stowage, but carrying capacity is sometimes reduced because of the missile's increased length.  The special Bomb Fin Mk 1 is a box-kite shape and eight inches longer than the standard tail for this bomb.


Control: Aerodynamic control is effected in range and azimuth by means of four movable nose deflectors independently controlled, which thus form quadrants of a cylindrical surface whose axis is parallel to that of the bomb.  The deflectors may be extended a maximum distance of 4 and 1/2 inches.  The movement of the deflectors is determined by the intelligence unit, which consists of the heat-detecting eye, gyro system, auxiliary electronic relays, servo motors, and battery.







1,600-pound "Bat" S.W.O.D. Mk 9 (Air-to-Surface Missile)


Overall length: 11.9 inches
Wing span: 10 feet
Total weight: 1,600 pounds
Warhead: 1,000-pound G.P. Bomb AN-M65


General: S.W.O.D. (Special Weapons Ordnance Device) Mk 9, or "Bat", is a glide bomb equipped with a radar homing set mounted in the nose.  It is designed primarily for attacking marine targets, and is effective for night or day attacks upon shipping in any weather in which the parent plane can fly.  The launching planes need not stay in the vicinity of the target, and may release as many as four of these missiles in salvo.

The airframe consists of plywood sections which are fitted around the Bomb AN-M65.  Control surfaces consists of an elevon on each wing which can be moved to control pitch or bank.  There are no control surfaces on the tail.

To ensure destruction of the intelligence system, the Demolition System Mk 122 is used.

Installation of the Fuzes Mk 235 and Mk 236, with their outside windmills and flexible arming stems, is standard.


Control: This missile has its own radar transmitter and receiver.  When the target is located on the scope of the monitor unit in the plane, it is put into the range step of the missile's scope and is automatically kept there.  At the correct instant, determined by a glide ratio scale, the missile is released and is guided to its target by the radar signal in its own scope.  The guiding radar supplies corrections to the servo system, which is also controlled by a gyro pilot, the device which maintains flight attitude.


Suspension: Standard bomb lugs are employed on the airframe.  Also, there is the multi-conductor cable connecting the missile's radar with the monitor set in the plane, known as the umbilical cord.


Demolition System: This destructor assembly consists of the S-122-11G switch, Junction Box Mk 1 Mod 0, primacord connectors, and ten Demolition Charges Mk 4.  The S-122-11G switch incorporates an inertia weight, held by a spring tension of 11G, which will topple if that force is exceeded in an impact.  When this inertia weight topples (it is mounted on a universal pivot) the contact bar, which has been transmitting the spring tension to the inertia weight, rotates because of the spring load and completes the electrical circuit across the contacts.  This switch has an arming stem, connected to windmill vanes mounted on the outside of the missile fuselage, which unscrews to arm the switch.  These vanes have an arming wire to prevent rotation before release from the parent aircraft.  On one side of the switch is a clear plastic inspection port.  Tension on the spring is pre-set at 11g when the switch is assembled at the factory.

When the switch completes the circuit, current from the battery sets off the electric blasting cap in the junction box, which fires the primacord connectors and then the TNT blocks, placed around the intelligence unit.


Remarks: The S.W.O.D. Mk 9 is commonly known as "the 1,000-pound Bat".  The S.W.O.D. Mk 10, built around a 2,000-pound bomb is not being actively developed, because it is felt that the 1,000-pound size is large enough for currently projected use.






Next Time: Bureau of Aeronautics Missiles

Monday, 29 October 2018

American Projectiles and Explosives - Army Practice Bombs





American Projectiles and Explosives



Practice Bombs





Army Practice Bombs




3-pound AN-Mk 5 Mod 1


See Navy Practice Bombs








20-pound M48


This is a dummy of the 20-pound Fragmentation Bomb AN-M41.  It has a two-ounce black-powder charge and uses the Fuze M110 or AN-M110A1 in the nose.  It is 21.8-inches long; weighs 19.7 pounds.  It is issued in practice bomb clusters M2 and M2A1.





23-pound M71 and M71A1


These are parachute-type practice fragmentation bombs for clustering.  They do not have a fuze or spotting charge, because of the presence of the parachute.  The parachute assembly is the M3, modified from the M4 by removal of the suspension assembly, hand assembly, and pull wire container.  M71 is 26.9 inches long; weighs 21 pounds.  M71A1 differs by the addition of the shoulder to the bomb nose.







100-pound M38A2



Overall length: 47.5 inches
Diameter: 8.13 inches
Weight (empty): 15.7 pounds
Weight (sand-loaded and spotting charge): 100 pounds


This bomb simulates a G.P. bomb of the same size.  The spotting charge is assembled in a sleeve at the base of the bomb, within the fin box.  Authorized spotting charges are M1A1, M3, and M4.






100-pound M75



Length: 47 inches
Diameter: 8 inches
Filler (hematite): 72 pounds
Total Weight: 101.3 pounds


This bomb is designed to provide a target reference for practice bombing over snow-covered ranges.  Resembling the chemical bomb of the same size, it consists of a light, sheet-metal case; a charge of red iron ore (hematite); a Burster M4; and a Fuze M108 in the nose.





100-pound M85


This model is a reinforced concrete design ordered to relieve a temporary shortage of the Practice Bomb M38A2 during the war.






Spotting Charge (Army)




M1A1

Overall length: 11.18 inches
Diameter: 3.43 inches
Weight: 4.25 pounds
Black-powder charge: 3 pounds
Bomb used in: M38A2


This type of spotting charge fits in the after end of the 100-pound Practice Bomb M38A2.  It produces a flash of flame and white smoke for observation of bombing accuracy.  When assembled in the bomb, the can of the charge protrudes two to three inches out of the bomb body.

The fuze is an integral part of the spotting charge assembly.  When the arming wire is pulled, the spring-loaded arming pin jumps out, leaving the inertia weight supported only by the combination firing pin and creep spring.  On impact, the inertia weight drives this firing pin into the shotgun-type primer, which, in turn, ignites the black powder.






M3: The Spotting charge M3 has a 2 and 1/3-pound dark smoke filling and a black-powder igniter.  It is 5/8 inches longer than the Spotting Charge M1A1, but otherwise is like it.  The M3, with its dark smoke filler, is well adapted for bombing practice over snow-covered terrain.  The black-powder igniter charge contains approximately 425 grains.  It is used in the Practice Bomb M38A2.


M5
Overall length: 7.37 inches
Diameter: 2.95 inches
Material: Glass
FS filler: 14.4 fluid ounces

The Spotting Charge M5 consists of a glass bottle filled with FS smoke mixture.  An ordinary bottle cap seals the mixture.  The bottle is held to the Practice Bomb M38A2 by a wire twisted around the neck of the bottle and attached to the tail vanes.  The charge assembly weighs 2.54 pounds.





Next Time: Guided Missiles - Introduction & Bureau of Ordnance Missiles

Monday, 22 October 2018

American Projectiles and Explosives - Navy Practice Bombs





American Projectiles and Explosives



Practice Bombs





Navy Practice Bombs




Miniature 3-pound Mk 3, Mk 4, AN-Mk 5, AN-Mk 23; and 4.5-pound AN-Mk 43


Overall length: 8.25 inches
Diameter: 8.1 inches

Color: Unpainted


These small, cast-alloy bombs have a tube along their longitudinal axis which houses the Signal Cartridge AN-Mk 4 or Mk 5, a pyrotechnic charge for spotting purposes.  The differences between these bombs are matters of size.  The Miniature Practice Bomb AN-Mk 43 weighs 4.5 pounds; the others of this series weigh 3 pounds.





Miniature 13-pound Mk 19 or Mk 19 Mod 1


This bomb is like the other miniatures, except that it is larger.  Its length is 13 inches, while its weight is 13 pounds.





"Old" Series Practice Bombs (Obsolete or being replaced)





No fuzes are used in these bombs, and they contain no spotting charge, being filled either with water or with wet sand.  The filling is usually stenciled on the body of the bomb.  To prevent freezing and splitting of cases at high altitudes, anti-freeze is added.  To improve spotting of hits, a spotting dye is also used.





"New" Series Practice Bombs




Mk 15 Mod 3 uses Spotting Signal Mk 7; the others use Mk 6 Mod 0.

This series bomb is a welded sheet-steel light-case design having identical dimensions to AN standard G.P. bombs, and uses AN standard G.P. bomb tails.  The bomb has, welded to its body, two suspension lugs spaced 14 inches apart.  Seven threaded recesses, located on the periphery at the approximate center of gravity, are for various hoisting conditions.  At 90 degrees, on each side of the suspension lugs and slightly before the hoisting recesses, are threaded opening to receive trunnions.

By means of a strap, the appropriate practice bomb signal, Mk 6 or Mk 7, may be attached to the tail assembly with the forward end of the signal seated in a recess in the after end of the bomb body.

A flat-nose attachment has been designed for use with the Practice Bomb Mk 15 Mod 3 for anti-submarine bombing practice.  The flat nose is installed by removing the nose-filling cap, slipping the attachment over the nose of the bomb, and then screwing the filling cap down tightly by hand to hold the attachment in place.  The flat nose will prevent ricochet at entrance angles as low as 9 degrees.

The 2,000-pound size container was designed for an incendiary or practice filler but, thus far, it is approved by the Bureau of Ordnance for practice filling, sand, only.  As designed for incendiary loads, it would take a nose fuze, the Burster Mk 1, and the Igniter Mk 40; however this is subject to change before Bureau approval of the bomb as an incendiary.  The Mk 67 has standard suspension lugs and provision for trunnions.






Practice Bomb Signals (Navy)




AN-Mk 4 and AN-Mk 5: For the miniature practice bombs, these signals allow observers to spot the impact of salvos.  The Practice Signal Cartridge AN-Mk 4 is an extra long 10-gauge shotgun shell which is inserted in the nose of the bomb.  On impact, the cartridge is fired, expelling a large puff of black smoke from the tail of the bomb.  The firing device consists of two shallow cups separated by a spacer, the firing pin extending through the bottom of one cup.  The Signal Cartridge Mk 5 is the same size but filled with fluorescein, which stains the water, giving a spot of longer duration than the AN-Mk 4.



Mk 6 Mod and Mk 7 Mod 0: These signals are essentially cans of black powder fitted with the Fuze Mk 247.  The Mk 6 is used in the Practice Bombs Mk 65 and Mk 66; the Mk 7 in the Bomb Mk 15 Mod 3.  They are attached to the rear of teh bomb by brackets or a strap arrangement.  The Signal Mk 7 is 13.08 inches long and 2 inches in diameter.  It has a total weight of 2.5 pounds.  It has a filling of one pound of black powder.  The Mk 6 is generally the same, except that the fuze is mounted off-center and the black-powder filling weighs two pounds.

The Fuze Mk 247 consists of an inertia weight held by a jump-out pin and a creep spring.  The detonator is a blank caliber .38 cartridge.  When the signal is placed in the bomb, the firing pin assembly is unscrewed and a blank caliber .38 cartridge inserted in the cartridge chamber.  The firing assembly is then re-inserted and secured by means of a lock nut.  At the time of loading the bomb into the plane, the arming wire is inserted through the jump-out pin, and the safety pin is then removed.  Upon release from the plane, the arming wire is withdrawn, allowing the jump-out pin to be thrown free, arming the signal.  Upon impact, weighted firing pin overcomes the creep spring and impinges upon the primer of the caliber .38 blank cartridge, which, in turn, ignites the main black-powder charge.







Next Time: Practice Bombs - Army

Monday, 15 October 2018

American Projectiles and Explosives - Chemical, Incendiary, Smoke - "AN" Series Bombs (Part 2)





American Projectiles and Explosives




Explosive Bombs





"AN" Series





100-pound Incendiary AN-M47 Series


AN-M47A2
Overall length: 48.9 inches
Body length: 39 inches
Body diameter: 8.1 inches
Wall thickness: 0.06 inches
Tail length: 12.9 inches
Tail width: 10.9 inches

Filling: Mustard Gas, White Phosphorus, or Gasoline Gel


Construction: The bomb body is a sheet-steel tube with a longitudinal seam weld.  The nose end is hemispherical.  A base plate at the rear end is welded to the tube.  Several bursters may be used interchangeably.  The burster runs the length of the bomb.  The Burster AN-M12 is a tube containing a 50-50 mixture of black powder and magnesium.  The Burster AN-M13 is a tube containing TNT and tetryl pellets at each end, and is used in conjunction with the Igniter AN-M9 (WP or Na).  The Na igniter will permit use over water.  Four vanes are welded to a truncated cone with box-type interior struts to form the tail.


Suspension: Horizontal suspension is provided by two eyebolts formed by holes in each half of the two suspension bands, the halves then being crimped together to form a complete band.  The bands are secured to the bomb body by tightening the bolts on the underside of the body.  One of the bands can be loosened and slipped to the center of gravity if single suspension is required.

Two clusters are now standardized to provide a single suspension for four to six bombs.  The Cluster Adapter M24 holds six AN-M47's ; and the M22 has a capacity of four AN-M47's.





M47A2 - Gas: Loaded with 68.5 pounds of mustard gas.  Complete round weighs 98 pounds.  Inside of body is coated with oil.  Equipped with Burster M4.


M47A1 - Gas: Differs from the M47A2 only in that the interior is coated with black acid-proof paint instead of oil.


M47A - Chemical: Original design, has wall thickness of only 1/32 inch.  Not use for H filling.


M47A2 - Smoke: Main filling is 100 pounds of white phosphorus, and total weight is 127 pounds.  Burster M4 is authorized for high-altitude bombing; Burster M18 is authorized for low-altitude bombing.  Burster M7 may be substituted for either.


M47A1 - Smoke: Like M47A2 - Smoke, with charge of 103 pounds WP and total weight of 129.5 pounds, and interior coated with black acid-proof paint.


AN-M47A2 - Incendiary: Loaded with 40-pound charge of gelled gasoline, either IM or NP, with total weight of 68.6 pounds.  Burster AN-M13 and Igniter AN-M9 (WP or Na) authorized for this bomb.


M47A1 - Incendiary: Like AN-M47A2, with interior coating of acid-proof paint instead of oil.


AN-M47A3 - Incendiary: Identical to AN-M47A2, except that tail assembly is three inches longer.


AN-M47A4 - Incendiary: On this modification, the suspension lugs are strengthened.










The Navy is procuring, at the present time [Manual Date 1949], Incendiary Bombs M47A2 loaded with PWP.  PWP consists of 75% WP and 25% plasticizer; it is more effective than WP, since it gives longer burning, reduces pillaring effect, and increases the anti-personnel effect.  The increased smoke efficiency is due to the larger particles of controlled size which result from the use of PWP.  The bomb contains 75 pounds of PWP and requires a Burster M20, which contains 3/4-inch-diameter tetryl pellets.








500-pound Incendiary AN-M76


Overall length: 59.2 inches
Body length: 45.3 inches
Body diameter: 14 inches
Wall thickness: 0.3 inches
Tail length: 13.9 inches
Tail width: 14.8 inches

Filling: Oil Gel PT 1

Weight of filling: 180 pounds
Total weight: 475 pounds
Charge/weight ratio: 38%


Construction: The body is of one-piece cast-steel construction, with a base plate welded to the body.  A burster tube 3.5 inches in diameter, 35.75 inches long, running through the center of the bomb, is welded to the nose and to the base plate.  The Adapter Booster M115 screws into the base plate.  The bomb tail is a cast-steel sleeve with four sheet-steel fins and internal box-type struts.  Suspension is accomplished by two suspension lugs welded on the body seven inches on each side of the center of gravity and by a single lug, 180 degrees removed at the center of gravity.


Operation: On impact, the fuzes function and detonate the 1.25-pound tetrytol burster in the burster tube and initiate the nine-pound white phosphorus igniter, which, in turn, ignites the main filling.

The bomb has a dispersal area of about 300 by 600 feet.


Remarks: White phosphorus is present in the igniter, and proper precautions should be taken in disposing of these bombs.  The incendiary mixture, PT 1, consisting essentially of paste of magnesium, gasoline, and a thickener, liberates heat at about four times that given off by the usual incendiary mixture IM.









500-pound Chemical AN-M78


Overall length: 59.25 inches
Body length: 46.7 inches
Body diameter: 14 inches
Wall thickness: 0.3 inches
Tail length: 13.9 inches
Tail width: 18.9 inches
Tail weight: 12.3 pounds


Filling: Hydrocyanic Acid (AC)
Weight of filling: 100 pounds
Total weight: 383 pounds
Charge/weight ratio: 26.1%

or

Filling: Phosgene (CG)
Weight of filling: 205 pounds
Total weight: 488 pounds
Charge/weight ratio: 42%

or

Filling: Cyanogen Chloride (CK)
Weight of filling: 165 pounds
Total weight: 448 pounds
Charge/weight ratio: 36.8%



Construction: In construction, the Chemical Bomb AN-M78 resembles the 500-pound G.P. Bomb AN-M64.  The body is of one-piece cast-steel construction with a Burster M15 well running the entire length of the bomb.  The burster is threaded internally at the nose to receive the nose fuze and at the rear to receive the Adapter Booster M115.  The base plug consists of a special forging welded to the case, containing the Needle Valve M1.  The tail is a standard box-type fin assembly secured to the bomb by a locking nut which threads onto the base plug.  Suspension is by two lugs seven inches on either side of the center of gravity, or by a single suspension lug 180 degrees removed at the center of gravity.


Remarks: The Adapter Booster M117 is used in conjunction with the Nose Fuze M127.  This nose fuze is required for aerial bursts with persistent gas agents.













1,000-pound Chemical AN-M79


Overall length: 69.5 inches
Body length: 53.6 inches
Body diameter: 18.6 inches
Wall thickness: 0.38 inches
Tail length: 18.5 inches
Tail width: 25.4 inches
Tail weight: 21.5 pounds


Filling: Hydrocyanic Acid (AC)
Weight of filling: 185 pounds
Total weight: 707 pounds
Charge/weight ratio: 26%

or

Filling: Phosgene (CG)
Weight of filling: 404 pounds
Total weight: 926 pounds
Charge/weight ratio: 44%



Construction: This chemical bomb resembles the 1,000-pound G.P. Bomb AN-M65, taking the same tail assembly, arming vanes, and fuzes.  The body is of one-piece cast-steel construction and has a steel burster well 2.5 inches in diameter which is placed axially through it and expanded in both the nose and the base plate before welding, thus eliminating any possibility of decomposition of chemical fillers due to the presence of crevices.  The base plate differs from that of the standard G.P. bomb in that it is a special forging welded to the case and containing the Needle Valve M1.  It also has a 1.25-inch filling hole closed by a soft iron gasket, a hard steel gasket plug, and a threaded closing plug.   The Booster M16 is used in the burster well and consists of a waterproof fiber tube filled with 4.45 pounds of tetrytol.  The standard 1,000-pound G.P. tail assembly consists of four fins welded to a sleeve which is held onto the base plate by a locking nut.  Horizontal suspension is accomplished by dual lugs 7 inches on either side of the center of gravity, or by a single lug 180 degrees removed at the center of gravity.


Operation: On impact with the ground, the tetrytol booster breaks the bomb case into a few large pieces without causing the chemical agent to "flash".  The initial cloud formed by the burst of this bomb, when filled with CG, covers an area of 100 yards in diameter within approximately eight to ten seconds.


Remarks: Attempts to disassemble the bomb or any of its components are to be avoided except for the fuzes, which may be removed provided it is necessary to return the bomb to storage.  Release of the filler is dangerous, and should not be undertaken except under exceptional circumstances.  In handling any damaged chemical bombs or in conducting surveillance tests by means of the Needle Valve M1, personnel should be equipped with rubber gloves and a gas mask.  The Adapter Booster M115A1 can be used in place of the M115.








Jettisonable fuel tanks ("fire bombs")




General: The "fire bomb" consists of a jettisonable fuel tank filled with gasoline gel (gasoline-Napalm mixture).  These bombs have been effective against personnel, wooden piers, inflammable stores, etc., with each bomb covering an area approximately 100 feet by 300 feet.

Various types of jettisonable fuel tanks are available for conversion into fire bombs.  A 150-gallon universal or interchangeable tank has been produced.  Stabilizers have been designed to give the fire bomb a more stable flight when dropped form a higher altitude.  The stabilizers are attached to the present tanks by a harness consisting of four cables which run along the longitudinal axis of the tank and are attached to a ring fitted around the nose.  The universal tank has clips welded to the after end, obviating the necessity of the nose ring and cable harness.


Filler: The filler is a gasoline-Napalm mixture.  Napalm consists of a mixture of basic aluminum soaps of fatty acids and napthenic acid, which in itself is inert and is used only to congeal the gasoline to the proper consistency.  Either 100 octane or 80 octane gasoline can be used, with 6% Napalm by weight added for the mixture.  Another powder, Marinco, consisting of 50% magnesium carbonate and 50% calcium carbonate, is added (7% of Napalm by weight) to prevent clogging in the outlet hose.

The Navy has developed the Incendiary Mixers Mk 1 Mod 0 and Mk 1 Mod 1, which mix the gasoline and Napalm in the correct proportions.





Next Time: Practice Bombs - Navy 

Monday, 1 October 2018

American Projectiles and Explosives - Chemical, Incendiary, Smoke - "AN" Series Bombs (Part 1)





American Projectiles and Explosives



Explosive Bombs



"AN" Series




2-pound Incendiary (Obsolete) AN-M52, AN-52A1, and AN-M52XA1


Overall length: 14.22 inches
Body length: 9.13 inches
Body diameter: 1.68 inches
Wall thickness: 0.35 inches
Tail length: 5.79 inches
Tail width: 1.68 inches

Filling: Thermate

Weight of filling: 0.4 pounds
Total weight: 2 pounds
Charge/weight ratio: 20%


Construction: The hexagonal cast-magnesium alloy body weighs 1.13 pounds.  The bore is one inch shorter than the body length, thus making a solid nose.  There are three vent holes below the primer cap assembly, to assist in initial burning.  The hexagonal sheet-metal tail is secured to the body with three screws.




Filling: Thermate is a composition of 80% Thermite and 20% first fire charge, see below.




Action: The spring-loaded safety plunger is depressed by the adjacent bomb; upon release from the cluster, it jumps out, leaving a thin brass cross holding the striker.  On impact, the striker breaks free from the cross, igniting the primer, first fire charge, and the thermate.  The thermate burns, igniting the magnesium alloy case.  The total burning time is eight minutes.


Remarks: In the Incendiary Bomb AN-M52A1, a primer of heavier metal is used, and the composition of the first fire charge is altered.  The AN-M52XA1 incorporates an explosive charge; otherwise it duplicates the AN-M52A1.






4-pound Incendiary AN-M50 Series



AN-M50A1
Overall length: 21.3 inches
Body length: 13.4 inches
Body diameter: 1.69 inches
Tail length: 8.7 inches
Tail width: 1.69 inches

Filling: Thermate

Weight of filling: 0.63 pounds
Total weight: 3.6 pounds
Charge/weight ratio: 17%


Construction: The hexagonal body of magnesium alloy, weighing 1.25 pounds, has an iron nose plug.  There are three vent holes below the primer cap assembly, to assist in initial burning.  The hexagonal sheet-metal tail is secured to the body with three screws.


Operation: The spring-loaded safety plunger is depressed by the adjacent bomb; upon release from the cluster, it jumps out, leaving a thin brass cross holding the striker, which breaks free on impact and ignites the primer.  The thermate burns, igniting the magnesium alloy case.  The total burning time is 9.5 to 10.5 minutes.




Remarks: AN-M50XA1. (Army: limited standard; Navy: obsolescent) contains 170 grains of black powder in a steel capsule at the nose, replacing a portion of the thermate.  The bomb burns approximately 1.5 minutes, until the black powder explodes, scattering burning magnesium over a wide radius.

AN-M50A2, similar to AN-M50A1, is waterproofed around the primer cap and first fire charge.

AN-M50XA2, similar to AN-M50XA1, has an explosive head consisting of a steel nose cap which houses three tetryl pellets, a detonator, and a delay fuse.  The delay fuse is ignited and sets off the detonator, exploding the tetryl pellets and projecting fragments of steel and burning magnesium.

AN-M50XA3 is identical to AN-M50XA2, except that the assembly around the primer cap and first fire charge is waterproofed.


Type A and Type B

AN-M50XA2 and AN-M50XA3 each have a Type A and a Type B.  Type A indicates that the delay from impact to explosion is two to four minutes; Type B indicates that the delay from impact to explosion is sixty to seventy seconds.

AN-M50TA2 is identical to AN-M50A2, except that it contains a secret toxic agent, which does not affect the burning properties of the incendiary.  Clusters carrying these bombs will have a green and a purple band painted around them.

AN-M50TXA3 combines the toxic feature of the AN-M50TA2 with the H.E. feature of the AN-M50XA3.  It is identical to the AN-M50TA2 as to appearance, except for a new longer, double-mortised steel nose, hollowed out to contain the explosive charge.  Because of the extra length of the nose, the column of therm-64C is 1 and 1/8 inches shorter.

The M50TXA3 is produced according to only one design or type, which gives a delay on the explosion of the H.E. charge of from 1 and 1/2 to 6 minutes.  A heat-sensitive detonator 2.556 inches long, which ignites at 300 degrees Celsius is housed in a hole drilled centrally through the upper part of the steel nose.  A 1/16-inch steel disk is placed in the bottom of the filling cavity of the bomb body, thus covering the top of the hole in the nose and insulating the detonator from the heat of the burning bomb.  The H.E. charge consists of tetryl pellets.






4-pound Incendiary AN-M54 Series (Obsolete)


AN-M54
Overall length: 21.35 inches
Body length: 13.6 inches
Body diameter: 1.69 inches
Tail length: 10 inches
Tail width: 1.69 inches

Filling: Thermate

Weight of filling: 1.6 pounds
Total weight: 4 pounds
Charge/weight ratio: 40%


Construction: The bomb body is a steel cylinder having a hexagonal nose plug.  The fuze is installed in the tail plug assembly.  There are three vent holes below the primer cap assembly, to assist in initial burning.  There is a hexagonal hollow sheet-steel tail.




Operation: The spring-loaded safety plunger is depressed by the adjacent bomb; upon release from the cluster, it jumps out, leaving the firing pin riding on a creep spring.  On impact, the firing pin overcomes its creep spring and strikes the primer, igniting the thermate, which melts the steel body and releases molten iron.


Remarks: AN-M54X is the same as AN-M54, except that next to the hexagonal nose plug a small portion of the thermate charge is replaced by a steel capsule containing 170 grains of black powder, which explodes and scatter the molten iron after the bomb has burned for about one minute.  It is limited standard for the Army, obsolete for the Navy.

AN-M54XA1 is the same as the AN-M54, except that inside the hexagonal nose plug there is a steel cylinder containing a tetryl high-explosive charge with a delay fuse and a detonator.  A thin spacer of magnesium is between the thermate and the fuse opening of the explosive cylinder.  After one minute of burning, the fuse is ignited, exploding the tetryl.  These bombs are no longer being procured for naval service, and should not be used except when Incendiary Bombs AN-M50A2 or AN-M69 are not available.  It is limited standard for the Army, obsolete for the Navy.











6-pound Incendiary AN-M69 and AN-M69X


Overall length: 19.5 inches
Body length: 19.5 inches
Body diameter: 2.87 inches
Wall thickness: 0.042 inches
Tail length (streamer): 54 inches

Filling: Gelled gasoline (NP or IM)

Weight of filling: 2.8 pounds
Total weight: 6 pounds
Charge/weight ratio: 46%


Construction: The bomb body is a hexagonal case with a nose cup welded to the forward end.  The nose cup, fuze and powder charges are sealed off from the rest of the case by an impact diaphragm and plug held in a cup-shaped sealing diaphragm.  The incendiary oil filling is held in a cheesecloth sock situated between the forward sealing diaphragm and the tail cup.

The tail assembly consists of a tail cup, tail retainer, and disc.  The tail cup is secured to the hexagonal case by beading, crimping, and heating.  Four gauze streamers, each 54 inches long, are attached to the tail retainer by the tail disc to stabilize the bomb and reduce the terminal velocity.




Operation: The spring-loaded safety plunger jumps out of the Fuze M1 upon release from the cluster, arming the fuze.  On impact, the striker overcomes its spring and detonates the primer cap, which ignites a lead-coated spitter fuse.  The spitter fuse burns from three to five seconds, allowing penetration, and ignites the black-powder booster charge.  This ignites the igniter-ejector charge consisting of two bags of black powder and oiled magnesium powder.  The combustion blows off the tail cup, ignites the incendiary filling and ejects it for a maximum of 75 yards.


Remarks: The bomb and the delay are calculated to permit penetration inside a structure before detonation.  The incendiary oil filling is of a very sticky composition and will normally adhere to any object, including vertical walls.

The AN-M69X incorporates a 4.5-ounce charge of tetryl to produce an anti-personnel effect.  Overall dimensions of the AN-M69X duplicate those of the AN-M69, but the amount of incendiary mixture is reduced (0.4 pounds less).  Operation of the Fuze M1 ignites a safety fuze lead terminating in the Detonator M106, which explodes the tetryl, fragmenting 65% of the bomb case after ejection of the incendiary material, following a pre-determined time delay of 0.5 to 6 minutes (30% - 1/2 minute; 30% - 2 minutes; 40% - 6 minutes).  The time delay is varied by adjusting the length of the safety fuse.





Next Time: Chemical, Incendiary, Smoke - "AN" Series Bombs (Part 2)