German Explosive Ordnance - Containers (Part 1)

German Explosives

Introduction

German containers can be subdivided into (1) those designed to scatter their contents before impact and (2) those intended to carry their contents safely to earth.  The latter are few in number and simple in principle.  They are a means of getting limited quantities of supplies to a specific location.  In general, they consist of a compartment to house the supplies and a parachute to bring it safely to Earth.  No explosive opening devices are incorporated.

Containers designed to scatter their contents from a height can be subdivided upon either of two bases:

a. Droppable containers and containers retained in the aircraft; or,

b. By content, as bombs, flares, or a combination load of both bombs and flares.

Non-droppable containers may be jettisoned by are primarily intended to be used repeatedly.  They are constructed to carry and scatter a great number of small incendiary bombs, the release mechanism being such that desired spacing of the bombs is possible.

Droppable containers are fitted with fuzing and opening devices designed to release the contained missiles after a predetermined time of fall from the aircraft.  Some of these containers are merely clustering devices, some are bomb shaped and hinge at the after end, others release missiles through large ports.

The contents of bomb containers are chiefly small anti-personnel or incendiary bombs and flares, the 1-, 1.3-, and 2-kg electron incendiary bombs, SD1, SD2, and SD10 A/P bombs being the ones most frequently used.  A common practice is to include a small number of SD2 bombs in a container of flares.

BDC 10, Cluser Container

Body Diameter: 10 inches

Filling: 5 - SC10; 5 - SD10A bombs

Construction: The bombs are held together by a band of metal 5 and 1/2 inches wide, and by a double "spider" which hooks through their suspension lugs, the outer spider being connected to the safety pins by small chains.  The top half of the band is attached to a beam carrying the suspension lug and a charging head similar to a Rheinmetall fuze head.  A lead from one plunger in this head goes to a socket, and into this socket fits a plug from the release device.  The lower half of the band is attached to the upper by wire hinges held together by two safety pins, one on each side.  These pins are attached to the outer arming spider by small chains.  The lower half of the band is split and held together by two "bottle screws" forming a means of tightening the band around the bombs during assembly.


Operation: On release from the aircraft, an electric cap in the arming spider is fired; this, after a short delay, ignites a small charge which blows off the from spider, thus pulling out the safety pins of the individual bombs and also the safety pins which hold the band together.  The bombs then separate and arm as they fall.  This carrier gives a much closer "pattern" on the ground than could be obtained by dropping the bombs in a stick.





AB 23 SD2 Container

Overall Length: 43.5 inches

Body Diameter: 8 inches
Tail Width: 11 inches
Total Weight: 101 pounds (estimate)

Filling: 23 SD2 bombs; strips of metal coated paper.


Color: The body is painted dark green and has two red bands running longitudinally the length of the tail fins.  Between the tail fins and suspension lugs are stenciled in white the following letters:

(79) B
o.V. fur 1000 bis 1900 M
m.V. fur 1900 bis 2500 M
2 cmal 42

In large black letters: AB23SD2

Between the fuze pocket and nose, in white:

79A Fur

m.V. fur 1000 bis 1900 M

Settings for fuzes are also stenciled on bomb.

Construction: The container holds 6 bombs in the forward compartment and 17 in the after compartment.  Compartments are created by sheet metal discs held in place by steel rods.  The case is divided into two halves longitudinally.  When the bombs are placed in the container, these two halves are held together by a shear wire which passes through a steel anvil, in the lower part of the fuze pocket.  When the aerial burst fuze operates, this wire is sheared by the explosion of the small exploder under the fuze.  The case opens and allows the bombs to fall out.  The fuze pocket is surrounded by a row of rivets which hold the steel washer in place to support the pocket.

By removing the two bulkheads on either side of the fuze pocket, these containers can be employed to drop strips of metal coated paper for disrupting radar operations.


Suspension: Horizontal by means of an eyebolt.







AB 24T SD2 Container

Color and Markings: Light grey or sky blue.  Stenciled on body in red:

"Vorn"; "Norfuraussen Aufhangungen"

In black: "AB 24T SD 2"



Construction: The AB 24T container has seven main parts: the safety pin, the spring-loaded locking pin, the cotter pin securing the spring-loaded locking pin, the locking arms, the retaining cotter pins, the suspension lug (secured to the locking pin) and the double "barreled" container.  Each "barrel" contains 12 SD2 bombs.  This container is very similar to the AB 70-3 container except for the release mechanism.

After the container has been loaded on the plane, the safety pin is removed.  On release, the spring-loaded locking pin, locking arms, and suspension lug assembly move downward.  This movement in conjunction with the force exerted by the 24 sets of SD2 wings causes the two outboard sides of the double "barreled" container to fly open, thereby releasing the SD2 bombs.


Suspension: Horizontal.


Remarks: The container is not suitable for release above 300 feet.  At this height bomb cover an area of 60 to 100 feet wide, and 100 to 200 feet long with greatest concentration in the center.

A German document states container cannot be jettisoned safely but aircraft are permitted to land with container.




AB 36 Container

Overall Length: 42 inches
Body Diameter: 8 inches
Filling: 36 1-kg 1B's or 24 2-kg 1B's


Color: Dark green overall


Construction: The AB 36 container is of sheet steel construction.  It is divided along its longitudinal axis into two halves which are welded to a hinged bottom plate.  The opening device is usually an electrically fired cartridge with a powder train delay; however, a clockwork release mechanism may be used.

The container is release.  After a short delay, the opening device functions.  The two halves of the container hinge outward and the bombs fall free.


Suspension: Horizontal




BSK 36 Container

BSK 36
Overall Length: 43 inches
Body Diameter: 8 inches
Filling: 16 2-kg 1B's



Color: Grey or aluminum overall


Construction: The BSK 36 is a rectangular aluminum container with a 43-inch vertical rod running up through the center.  The road carries three trays with felt pads on which the incendiary bombs are stacked vertically around the rod.  When released, the rod and the bombs fall away; the rectangular container stays with the plane.


Suspension: Vertical.  The rod carries a lug at its top end which is engaged with the bomb rack of the carry aircraft.




Three-Sided Container

Overall Length: 42 inches
Body Diameter: 8.5 inches
Filling: 36 1-kg 1B's


Color: Grey or black overall.  The clockwork release mechanism has inscribed on it:
"Achtung!" (note)
"Versogerungswerk Auf Ziechen" (Wind up retarding mechanism)


Construction: The three-sided container is of sheet steel construction.  It consists of three side pieces and a separate piece which together form a cylinder.  A clockwork release mechanism is used to dump the load by separating the cylinder parts.


Suspension: Vertical or horizontal.




AB 42 Container

Overall Length: 28 and 1/2 inches
Width: 7 and 3/4 inches
Height: 9 inches
Filling: 42 1-kg incendiaries


Color: Black or grey overall.  "AB 42" is stenciled in red on the end.


Construction: The container is constructed of wood with small metal fittings.  Three double compartments 13 and 3/4 inches long are formed by four wooden partitions 7/16 inches thick.  Compartments are rectangular in shape with corners cut off.  The top and bottom spars are made up of five thin pieces of wood glued and nailed together.  They are of flat cross sections and their inner sides are shaped to form a seating for two rows of 1-kg incendiary bombs.  The three center spars are of circular cross section 1 inch in diameter.  They pass through holes in the inner partitions and are glued into recesses cut in the end partitions.  Each compartment contains 14 1-kg incendiary bombs held in a cluster against the round wooden spars by a steel securing band which passes through slots in the top and bottom spars.  The top spar carries a suspension lug block, the charging head and the fuze holder.  Two insulated wires passing through a channel cut in the top spar connect the fuze with the charging head.

From the side of the fuze holder a short metal tab projects through a slot in the side of the metal cover plate.  A bowden cable, passing through three aluminum channel guides, is connected to the tab at one end and a weak anchorage on the remote end of the container at the other.  The cable has three small steel blocks, each located by two small bolts.  Each bomb securing band is fastened by a release catch on one end of the band, which passes through a slot in the other end, and which has a small hole drilled in it.  Securing pins passing through these holes lock the bands.  These pins are carried by three small plates, which are threaded on the bowden cable.  Adjusting screws are provided for the band assembly.

On release from the aircraft,t he fuze is charged.  After a set delay, the fuze fires, forcing off  the part of the fuze holder to which the metal tab is attached.  The bowden wire is torn away from its anchorage at the remote end and the three blocks bearing against the flanges of the plates effect the withdrawal of the securing pins.  The securing bands are then free to open and release the bombs.


Suspension: Horizontal

Next Time: Containers (Part 2)

Source: German Explosive Ordnance Vol. 1: Bombs, Rockets, Grenades, Mines, Fuzes & Igniters

German Explosive Ordnance - Pyrotechnics (Part 5)

German Explosives

Single Unit Ground Marker, Mark 3 Grun

Overall Length: 13 inches

Body Length: 11.75 inches
Body Diameter: 3.25 inches
Wall Thickness: 0.25 inches
Filling: Flare Composition


Colour and Markings: Fawn-colored.  "Mark 3 Grun"


Construction: The outer casing consists of a thin sheet steel cylinder with a single seam running the entire length of the case.  Two sheet steel strengthening bands are fitted externally to the steel cylinder.  Each strengthening band is secured in position by a nut and bolt.  A cardboard cylinder within the steel cylinder forms a lining for the pyrotechnic composition.  A cylindrical wooden block is housed in the upper portion of the cardboard cylinder.  The wooden block, cardboard cylinder, and a steel cylinder are secured together by means of three small panel pins.  A pressed steel cover cap fits over the upper portion of the cardboard cylinder and wooden block protruding beyond the steel cylinder.  The cover cap is designed to permit entry of the fuze body but engages the flange on the upper portion of the fuze body.  The cover cap is secured to the cardboard cylinder and wooden block by means of three panel pins.

The steel housing for the arming vane is secured to the cover cap by means of two nuts and screws, the screws being fitted with distance pieces.  The wooden block is countersunk at two points to accommodate the screw heads.  The flanged portion of the arming vane housing has eight vent holes.  The lower cylindrical portion of the housing has a slot for observing the position of the arming spindle of the fuze; it is also recessed at two points on the lower surface to permit the housing to fit over and engage the upper surface of the projectile lugs of the fuze.  The upper cylindrical portion of the housing is drilled at four points for housing the safety wire; it also has a recess for accommodating the arming wire attachment lug on the arming vane.  The arming vane consists of a circular sheet steel plate, two segments of which are bent over in opposite directions at an angle of 45 degrees.  Ten inches of light steel cable is secured to the arming vane and the arming spindle of the fuze.  The arming vane is a loose fit within the arming vane housing.  The steel cable is stowed below the arming vane, the latter being retained in position by the safety wire.

The fuze is a normal (67) fuze fitted with a bakelite gaine case filled with gunpowder.  It is believed that a bursting charge is incorporated in the lower portion of the pyrotechnic filling in order to discourage attempts to extinguish the target marker on the ground.



Operation: On release from the aircraft and subsequent opening of the container, the safety wire is withdrawn presumably by means of a static cord.  Alternatively, the safety wire may be withdrawn prior to stowing the marker in the container.  The current air passing through the vent holes in the arming vane ejects the arming vane.  By reason of its shape, the arming vane is rotated as the missile falls.  This rotation unscrews the arming spindle of the fuze thus permitting the clockwork mechanism of the fuze to function.

The missile falls to the ground and once the present delay on the fuze has expired, the gunpowder in the gaine case is ignited.  The resulting flash ignites the pyrotechnic composition and ejects the cover cap, fuze, and arming vane housing.

The pyrotechnic filling burns with a strong greenish flame for approximately 3.5 minutes.  A slight explosion occurs when the bursting charge is ignited.






Parachute Recognition Smoke Generator

Overall Length: 20 inches

Maximum Diameter: 8 inches
Total weight: 27.5 pounds

Filling: Smoke producing composition.
(Heat stable blue dye [42%] mixed with potassium chlorate [33%] and lactose [25%])



Construction: The smoke generator has an aluminum cylindrical-shaped body divided into two sections.  One section houses the smoke producing parts and the other the parachute.

The smoke-producing section is divided into sections by 3 metal plates.  These metal plates are connected by 12 metal distance rods.  Eight of these distance rods are equally spaced around the circumference of the plates while the remaining four are spaced equal distance from and closer to the center.  The smoke canisters are held in two tiers, each of four canisters.  The arrangement of rods ensures that the smoke canisters are firmly held.  Four 1.4-inch holes are drilled into the plates for the igniting tubes.

The individual smoke canisters are aluminum cylinders lined with stiff waterproof paper.  They contain four annular blocks, three of smoke composition and one of a clay-like substance.  The priming composition is gunpowder and each of the three smoke composition blocks has a small quantity placed in loose at the base before pressing to ensure ignition between one block and the next.  Each canister emits smoke of good density for about 26 seconds.

The ignition pellets are arranged to accept flash of ejection charge and distribute it to the four ignition tubes, each of which pierce the center of two smoke canisters.  A total of 14 gunpowder ignition pellets are packed in these tubes.  The ejection charge consists of one-half ounce of fine mesh gunpowder.  It is positioned directly below the pull igniter.  Below this is the first metal ejector plate.  It has a hole in the center of which allows the flash to ignite the ignition pellets.  In the lower part of the container, directly above the parachute, the second ejector plate is positioned.  This prevents the parachute from becoming damaged or entangled in the outer container.

The parachute canopy is made of continuous filament viscose rayon.  It is built up from 12 panels each 4 feet 11 inches wide by 6 feet 10 inches high.  Attached to the canopy are 12 rigging lines each 13 feet long which in turn are attached to an eyeloop which is secured to the top plate of the container.


Operation: The transit cap is removed; then the friction igniter knob is unscrewed and pulled longitudinally.  The generator is then allowed to fall clear.  After a delay of 4 to 5 seconds, the igniter functions and the flash from the detonator passes to the ejector charge, which on exploding forces out the contents of the container to be supported by parachute when this opens.  Pellets on ignition pass the flash to the perforated ignition tubes.







"Lux N" (Flame Float)

Overall Length: 3 feet 6 inches

Body Diameter: 8 inches
Tail length: 15.75 inches


Color: Yellow overall with the following stenciled markings:

Around body
"LUX N
969"

At tail along body
"VOR HANDABWURF SICHERUNGSSEIL AUSZIEHEN"

Diagonally at tail
"NACH RETTUNG GERAT VERSENKEN DURCH ENFERNEN DER FLUGEL SCRAUBEN"

Construction: The body is made of two hollow cylinders welded together.  The nose is welded to the body and is provided with a welded collar which is threaded to receive either a nose plug or a suspension lug.  Just forward of the normal suspension lug is an inset similar to a Rheinmetal fuze head.  Four sheet steel fins form the tail.  Projecting from the base is a small compartment around which the silk mooring cord may be coiled.  Two wooden grips are attached to this cord.  Two winged nut screw plugs are fitted on opposite sides of this compartment giving access to the buoyancy compartment.  Internally the float is divided into six compartments - the calcium carbide container, the acetylene gas compression chamber, the calcium phosphide container, the buoyancy chamber, the water inlet chamber, and the combustion container.

On leaving the aircraft, a rubber bung is withdrawn by pulling the arming wire.  The float sinks below the surface on its initial dive and water enters the ports and passes down the inlet tube into the calcium phosphide chamber thus generating phosphine.  The phosphine passes up the outlet tube through the nonreturn valve to the burner where it ignites spontaneously to form a pilot jet.  At the same time water enters through the channels in the nose and passes through a perforate tube into the carbide compartment.  The acetylene evolved passes through the perforated diaphragm into one compression chamber and thence to the burner where it is igniter by the pilot jet.

According to the instructions stenciled on the body of the float, once it has served its purpose, should be sunk by removing the winged nut screws which permits the buoyancy chamber to fill with water.


Suspension: Vertical or horizontal.







Flame Float, Lux S (Type 1, Type 2, Type 3)

Type 1
Overall length: 20.9 inches
Body diameter: 5.5 inches
Weight of filling: 3.9 pounds

Type 2
Overall length: 20.9 inches
Body diameter: 5.5 inches
Weight of filling: 13.5 pounds

Type 3
Overall length: 20.9 inches
Body diameter: 5 inches

Weight of filling: 13 pounds

Filling: Calcium carbide and calcium phosphide.

Total weight: 14.3 pounds

Color and Markings: Yellow overall with the word "LUX S" stenciled in black on side.



Construction: The body is sheet metal and in the form of a cylinder.  At the side there is a lever, the fixed end being embedded in lead.  At the top there is a capstan formed by two flange-like pieces of metal.  A silken mooring cord is wound around the capstan and attached at one end to a wooden float and by the other end to one of the flanges.  A central jet projects from the top of the cylinder from which acetylene gas is emitted when the float is activated.  It is enclosed in a short tube, welded to the top of the cylinder to form the combustion chamber.  A second duct to emit phosgene gas is formed by a narrow tube curving toward the central jet through a slot in the side of the combustion chamber.  The slot also allows any water collecting in the combustion chamber to drain away.


Operation: The lever arm located at the side of the flare is freed from its safety wire and pulled outward, breaking it away so as to leave a hole of entry for water.  When in the sea, water enters to react with calcium phosphide and carbide.  Acetylene gas is produced from its jet and is ignited by phosphine gas emerging from the other jet.  Phosphine ignites immediately on exposure to air, thus if the acetylene is extinguished by a wave, it will be re-ignited by the phosphine.  It takes approximately 3 minutes from the time of immersion for the phosphine to be evolved in sufficient quantity to produce flame.  The acetylene gas may take a little longer and may not ignite until a period of 10 minutes has elapsed.



Remarks: All types are similar in operation with only slight variations in construction and appearance.  The Lux S differs little in internal functioning from the Lux M.

The Lux S can be seen from a distance of approximately 6.5 kilometers at normal eye level when the observer is standing 3 meters above sea level.

Next Time: Containers (Part 1)

Source: German Explosive Ordnance Vol. 1: Bombs, Rockets, Grenades, Mines, Fuzes & Igniters

German Explosive Ordnance - Pyrotechnics (Part 4)

German Explosives

BLC 50 Photoflash Bomb

Overall Length: 42 inches

Maximum Body Diameter: 8 inches
Length of Detonating Fuse: 31.5 inches
Weight of Standard Charge: 15 kilograms
Peaklight Intensity: 450 million Hefner candles
Time of Peak Intensity: 70 milliseconds
Total Light Output: 63 million Int. candle seconds



General: It has been found that the Luftwaffe employed a photoflash bomb containing powdered aluminum, which was scattered into the surrounding air by the explosion of the inner core of black powder.  Due to the heat of the explosion, the aluminum powder burned in the oxygen of the air and produced a rapid flash.  The bomb weighed considerably more than the conventional type of photoflash bomb, which employs an intimate mixture of powdered oxidizing agent and magnesium or aluminum, and it produced a slightly lower peak candle power output.   The time to reach peak intensity was also lower.  However, the German bomb possessed a very great advantage in the fact that it was not sensitive to bullet impact, and was therefore much safer to employ.



Description: The BLC 50 50 photoflash bomb consists of a comparatively light steel casing approximately 42.9 inches long and 8 inches in diameter.  The total weight of the bomb is 42kg.  There is a heavy concrete nose piece which acts as a ballast to stabilize the flight of the bomb.  The bomb itself consists of three approximately concentric tubes.  The outer tube contains 15kg of aluminum "pyroschliff", which is an extremely fine, flaked aluminum powder, having the following characteristics:

-Metal Content: 87 - 92%
-Fat content: Less than 0.1%
-Moisture: Less than 0.5%

Another tube placed within the outer tube contains 3.5kg of black powder, serving as the explosive which scatters and ignites the outer charge of aluminum powder.  The black powder, "Marine-Geschutz" pluver, possesses the following characteristics:

-Moisture content: Less than 1.3%
-Granulation range: 0.68 to 1.3 mm

Chemical Composition:
-Potassium Nitrate: 75%
-Sulphur: 9%
-Beech charcoal: 16%


The black powder is exploded by means of an 80cm length of detonating fuse which is place inside a third tube passing through the black powder charge.  The ends of the detonating fuse are dipped in a 4% solution of collodion, and allowed to dry.

The bomb is ignited by means of the standard type of electrically ignited delay fuse which is inserted in the fuse well in the side of the bomb.



Remarks:  In order to increase the usable light output of the BLC 50 photoflash bomb, the following researches were carried out recently:

A. The fine, flanker aluminum "pyroschliff" powder was replaced with an atomized aluminum powder called "griess".  The new, atomized powder possessed spherical particles, and therefore had approximately twice the apparent density of the flaked form.  Approximately 30 kilograms of the atomized powder could be placed in the volume formerly occupied by 15 kgs of aluminum "pyroschliff".  This procedure increased the peak intensity from 450 to 800 million Hefner candles.  However, the flash was very much slower, that is, the time to reach peak intensity was longer, and the total duration of the flash was longer.  It was also stated that the results could not be reproduced, because of variations in the characteristics of the atomized aluminum powder.



B. The 15kg charge of flaked aluminum powder was replaced by 28kgs of pellets (13mm diameter and 7mm height) composed of the following composition:

-Magnesium powder: 39%
-Barium nitrate: 53%
-Synthetic phenolic resin: 6%
-Talcum: 2%

These pellets were packed int he outer tube of the bomb together with 9kg of black powder and then a length of detonating fuse added.

This bomb, when exploded, produced a peak intensity which was only 80 percent of that of the standard BLC 50 bomb.  The time to reach peak intensity (100 milliseconds) was longer than that of the standard bomb, and the durations of the flash at one-half and one-tenth maximum intensity were much longer (230 and 550 milliseconds, respectively).  In addition, this bomb was found to be sensitive to bullet impact.


C. The standard 15kg aluminum powder charge was replaced by one huge pellet weighing 24kg.  The composition of the pellet was as follows:

-PTN: 50%
-Magnesium powder: 50%

The results of the firing tests conducted with this bomb were very disappointing.  They indicated a peak intensity only one-fifth of that of the standard bomb.  The flash was very slow, since the durations at one-half and one-tenth maximum intensity were 500 and 1,000 milliseconds, respectively.



D. The standard 15kg charge of aluminum was replaced by one composed of 28 pellets of the following composition:

-Sodium nitrate: 45%
-Magnesium: 50%
-Wax: 5%

Each pellet had hollow axial space, weighed 900 gm, and measured 60mm in diameter and 220mm in height.  The total weight of pellets placed in the bomb was 25.2 kg.  A length of detonating fuse was passed through each pellet and all of the ends of the fuze bound together.

The results of the firing tests conducted with this bomb indicated that the total peak intensity was approximately the same as that of the standard bomb.  However, the peak intensity measured through a yellow filter (which is considered important when photographing at night in the presence of a slight ground haze) was 20 percent greater.  Although the time intensity curve for the flash rose at the same rate as that of the standard bomb, the duration of the flash was very much longer, being 400 and 800 milliseconds at one-half and one-tenth maximum intensity, respectively.

This indicated that the total light output was very much greater than the standard bomb.  However, this light would not be usable if short exposures were employed.  In addition, the bomb was found to be sensitive to bullet impact.



E.  In order to decrease the time of the flash, and thereby raise the peak intensity and concentrate it in a small time interval, a bomb was loaded using the same general procedure as C, but pressing each pyrotechnic pellet into a separate steel case in order to increase the confinement.  A detonating fuze was inserted through each pellet as before.  The results of the tests with this bomb showed that the peak intensity could not be appreciably raised.  The bomb was also found to be sensitive to bullet impact.


F.  The results of all of the above tests indicated that the peak intensity, and therefore the total usable light output, in a short exposure time could not be increased appreciably.  However, most of the experimental bombs produced longer flash durations, with intensities consistently as high as that of the standard bomb.  Therefore, efforts were directed toward the utilization of longer exposure times.  A camera, known as the "E-5", employing a moving film holder to compensate the movement of the airplane, was developed recently.  The "E-5" camera makes possible the use of very long exposure times, and thus permits the use of photoflash bombs producing a long, slow flash.  In this manner the total usable light output can be multiplied three to four times.


Safe photoflash bomb, employing outer layers of large amounts of atomized magnesium or aluminum powder can then be used, because all of the light of the relatively slow flash is useful.







Target Indicator (Red)

Overall Length: 13.25 inches

Body Diameter: 3.4 inches
Filling: Flare composition



Construction: The flare composition is contained in a cardboard cylinder which fits into an aluminum casing and seats against a washer touching the suspension plate.  It is secured at the nose end by two plates, the end of the casing being slightly indented to hold these.  The suspension plate holds an eye to take the parachute shackle, and a pull igniter which is connected by a 4 and 3/4 inch length of safety fuse to a small bag containing gunpowder.  This serves both to set off the igniter pellet in the top of the candle and to eject the latter from the casing when it falls freely to earth and acts as a ground marker.  The pull igniter is attached to the loop of the shroud lines by a cord; the opening of the parachute gives the necessary pull for operating the igniter.  There are two small fins at the nose end of the container; their purpose is not clear.


Suspension: The indicator is carried in Mark 250 BK-3SD2 container.



Remarks: Container from which indicators were recovered was marked with a red band corresponding to the color of the flare.





Marker Bomb (Sea)

Overall Length: 4 feet 8 and 1/2 inches

Body Diameter: 8 inches
Wall Thickness: 1/32 inches
Tail length: 9 inches
Tail width: 10 inches


Color: Painted yellow overall

Construction: The sheet steel, bomb-shaped body is supported internally by a series of eight annular strengthening bulkheads.  Welded to the after end of the body is a tail cone which terminates in a short parallel sided tube over which is assembled an adapter designed to accept the aluminum body of the lamp unit.  Four stabilizing fins are welded to the tail cone and strengthened by metal struts.  The nose portion of the bomb body is welded to the parallel-sided portion of the body and terminates in an annular flange to which the solid steel nose plug is bolted through a castellated collar.  The rear face of the nose plug has been recessed to form a housing approximately 1 and 1/2 inches deep for the battery unit which is assembled inside a central tube of drawn steel 18 and 1/2 inches long and 4 and 1/8 inches internal diameter.  The battery unit consists of a series of small dry cells contained with an insulate cylinder.

Provision is made for six cells in each later, the cells being arranged around a central tube through which a retaining bolt passes to secure it to the nose plug.  The rear end of this tube is closed by means of a closing cap to which an annular brass contact disc is secured and which is held in place by means of a washer and nut.  A contact is located in the tail adapter by a grub screw and slot arrangement.  Passing through the contact bush and screwing into the tail adapter is a lamp unit which consists of a cast aluminum body with an insulated contact rod secured through the base of the casting by two grub screws.  At the base of the rod, a spring switch is mounted with leads to the battery unit and the lamp unit.

Positioned between the two arms of the spring switch is an insulated inertia bolt which breaks the contact until closed on impact.  The lamp unit is spring mounted to protect it from shock and covered by a Lucite type dome.  When the marker is released from the aircraft, the inertia bolt is positioned between the plates of the spring switch and one side of the circuit between the lamp and the batteries is broken.  On impact, the inertia bolt is forced out of position and the circuit between the lamp and battery is completed.  As the batteries fill, only a portion of the bomb body and all joints are made tight by rubber washers, the marker floats on the surface of the water, and it is assumed, provides a recognition or bearing point for aircraft.



Suspension: Vertical








Lux EZ 50 SC (Sea Marker)

Color and Markings: The complete marker is colored fawn and has the following stenciled in black on the side:

"Kennung K.B., Seiklange 200m, ZW"
"Verbrauchen B 15"

On the nose is stenciled: LUX.E 250

Construction: The marker is constructed in two parts.  The rear portion consists of a cylindrical steel container to the rear end of which are attached four metal fins; behind these is situated a flat metal base plate of the same diameter as the marker and having attached to it a spring-loaded platform which in turn houses a green silk drogue.  Projecting also from the base plate is a frosted globe.

At the other extremity of the rear portion of the marker is situated a fuze pocket sealed by a steel disc and locking ring.  Forward of this and next to it is a carrying lug.  The front portion of the marker consists of a heavy steel nose which is internally attached to the rear portion, the joint being visible as a thing groove.  Screwed to the end of the nose is a circular steel plate which serves as a kopfring.

The forward portion of the marker contains another fuze pocket.  Forward of this is a small hole covered by a thin steel disc held by a spring clip; a similar hole is situated on the other side of the nose diametrically opposite to it.  Passing down the side of the marker is a piece of thin S.W.R. which passes through a small hole where the two halves of the marker join together.


Operation: Immediately upon release from the aircraft, the drogue is pulled out by means of a rip cord attached to the aircraft and the (17) A fuse in the forward end of the marker is charged.  The speed of the marker's fall is slightly reduced by the drogue.  Upon striking the water it sinks to the bottom, burying its nose.

After a preset delay up to 72 hours, the (17) A fuze fires a small charge of gunpowder contained in a bakelite gaine.  The pressure created by this explosion releases the catch holding the two halves of the marker together.  The front portion of the marker is forced off the rear portion by its spring-loaded plunger.  As soon as the two halves separate, the electrical hydrostatic switch on the rear portion is free to close on release of water pressure.  The rear portion of the marker having positive buoyancy now rises to the surface of the water, unwinding as it does so the S.W.R. contained on the drum of the forward portion of the marker which now acts as an anchor.

As soon as the cylindrical rear portion reaches the surface, the hydrostatic switch closes.  The battery is now connected up in parallel with the motor and the lamp.  The motor revolves and by means of a gear train operates a contact breaker, thus causing the 24-watt bulb to emit a series of light flashes.  The frequency, alternation, and duration of the flashes emitted vary in each marker.

The closing of the hydrostatic switch also allows the battery to charge the (17) A fuze.  After a delay the fuze fires.  The electro-magnetic current inducer attached to it produces a flow of electricity which fires two ignition bridges in the end plates of the marker.  The flooder plugs are blown out thus destroying the marker by permitting it to sink.



Suspension: Horizontal by standard German eyebolt.


Remarks: A soluble plug on the drogue housing allows the drogue to break free from the marker after it has entered the water.

Next Time: Pyrotechnics (Part 5)

Source: German Explosive Ordnance Vol. 1: Bombs, Rockets, Grenades, Mines, Fuzes & Igniters