Showing posts with label 9lb. Show all posts
Showing posts with label 9lb. Show all posts

Sunday, 19 March 2017

British Explosive Ordnance - Rocket Flares, Wire-Barrage and Pyrotechnic Rockets







British Explosive Ordnance





 Rocket Flares Introduction


This chapter is concerned with rocket assemblies which carry an illuminating candle.  A parachute may suspend the flare candle for purposes of illumination after ejection, as in the case of the 2-inch and 3-inch rocket flares, or the candle may not be either ejected or supported by a parachute, as in the case of the 2-inch target rocket, which merely furnishes a moving, visible target for anti-aircraft practice.

The section of the rocket flare containing the candle, parachute (if present), and initiating device, is called the flare head.  It corresponds to the "shell" in H.E. rockets.  The heads of the rocket flares discussed in this chapter are attached to the rocket motor by the conventional shell ring.






2-in UP Rocket Flare (Service)



Flare Head
Overall length: 22 inches (approx.)
Diameter: 2.25 inches
Total weight: 4.75 pounds
Fuzes used: Thermal Initiator


Rocket Motor:
Overall length: 31 inches (approx.)
Diameter: 2.25 inches
Width of fins: 2.375 inches
Total weight: 7.5 pounds
Propellant: Tubular cordite
Propellant weight: 2.5 pounds
Burning time at 60 degrees Fahrenheit: 0.9 seconds

  
General: This flare is used to illuminate enemy targets at night.  It is used in conjunction with medium-caliber guns.  A flare launcher is mounted on either side of the gun shield at a fixed angle of 30 degrees.  This arrangement makes it possible to keep a target illuminated and at the same time engage it with the main armament.


Description

Rocket Flare Head, 2-inch, No.1 Mks I and II, No.2 Mk I, and No.3 Mk I: The flare head consists of a cylindrical tinned-plate container, with two cannelures near the base.  Inserted in the container is a metal canister, which houses the illuminating candle and attached parachute assembly.  A ballistic cap is fitted to the forward end of the container, to which is secured with adhesive tape.  A base socket is secured to the other end of the container by indenting the cannelures.  The base socket screws into the shell ring of the rocket motor and contains the thermal ejector.  This latter consists of a steel base plate, in the center of which is a metal septum of accurately machined thickness.  The lower end of a length of safety fuze (primary delay), cut to burn approximately 22 seconds, makes contact with 2 and 1/2 grains of lead-dinitroresorcinate (LDNR), which is stemmed into the septum recess.  The upper end of the safety fuze extends into a magazine containing about 40 grains of G.12 gunpowder (primary ejection charge).  Protruding from the base end of the canister is a short length of safety fuze (secondary delay) cut to burn for 3 seconds.  The proximity to the primary ejection charge, and its upper end projects into a magazine containing about 40 grains of G.12 gunpowder (secondary ejection charge).

The different flare heads vary only in the contents ejector employed, as follows: Flare Head No.1 Mk I uses Ejector, Contents No.4 Mk I (with 22-sec delay); Flare Head No.1 Mk II uses Ejector, Contents, No.4 Mk II (with 18-sec delay); Flare Head No.2 Mk I uses Ejector, Contents, No.5 Mk I (with 9-sec delay); and Flare Head No.3 Mk I uses Ejector, Contents, No.8 Mk I.







Tail, Propelling, Rocket, 2-inch, Mks VI and VII: The Motor Mk VI is identical to the 2-inch Motor Mk III, except that the obturator of the latter is perforated, while that of the former is not, but rather is rust-proofed to allow free conduction of heat to the thermal fuze in the flare head.  For this reason, Motors Mk VI are marked T.I., indicating their use with thermal initiators.  No other motor may be used with the flare head.

The Motor Mk VII differs from the Mk VI in that the castellations in the charge are omitted and a metal cased cylindrical igniter is employed.


Operation: When the rocket is fired, heat from the burning propellant grain is transmitted through the head obturator and the thin septum of the thermal ejector, igniting the LDNR and initiating the lower end of the primary delay.  After a set delay, the primary ejection charge is ignited, and the canister is ejected from the container in a forward direction.  The secondary delay is initiated by the flash from the primary ejection charge, and, after three seconds, initiates the secondary ejection charge, which ignites the candle and ejects the parachute, cable, and candle in a forward direction from the canister.  The parachute opens when ejected from the canister, and the lighted flare candle is suspended in mid-air.

The purpose of the secondary delay is to allow the velocity of the canister to be reduced to a speed at which the flare and parachute assembly may be ejected without danger of break-up.

The flare is ejected at a range of about 5,000 yards and an altitude of about 2,000 feet.  The duration of burning of the flare is about 70 seconds.


Remarks: This flare, fitted with 4-inch by 1-inch fins, may be fired from a spiral launcher to obtain greater accuracy. 

The complete round (flare head and motor) weighs 12.25 pounds and measures 51 inches in overall length.






2-in UP Target Rocket (Service)
   


Target Head

Overall length: 15.75 inches
Diameter: 2.25 inches
Total weight: 4.5 pounds
Fuzing: Special igniter

  

Rocket Motor

Overall length: 20.25 inches
Diameter: 2.25inches
Width of fins: 2.375 inches
Total weight: 6 pounds
Propellant: Cogged cordite
Propellant weight: 1.25 pounds
Burning time: 0.45 seconds


  
General: This rocket is designed to give, by means of an integral flare, a visible aiming mark for anti-aircraft batteries.  The target has a range of about 5,000 yards at a speed of 250 to 400 knots.  The target can be used at night and is suitable for use from either aboard ship or ashore.





Description

Head, Rocket Target, 2-inch, Mk I: The target head consists of a thin sheet-metal container holding a flare candle.  Separated from the flare candle by a steel washer is an externally threaded spigot, by which the head is attached to the shell ring of the rocket motor.  The spigot is fixed to the target head body by means of a double crimp.  A weight is fitted into the forward end of the body and is fixed to the body by four screws.  A ballistic cap is crimped to the forward end of the weight.

Four holes are drilled through the body and the weight just before the flare candle, and a similar set of four holes is drilled abaft the candle through the body and the spigot.  The two sets of holes are covered with a strip of tape 1.5 inches wide, which is wrapped around the body.

An igniter mechanism, consisting of a diaphragm-operated striker, a percussion cap, and a gunpowder charge, is inserted into the after end of the spigot and is held in place by a threaded locking ring.






Tail, Propelling, Rocket Target, Mk I: This motor consists of a cylindrical steel body with a shell ring fixed in the forward end by eight locking pins held in engagement by a circular band spring.  Separated from the shell ring by a steel, flanged support ring, is an igniter in a cylindrical metal container.  Leads from the igniter extend through the central annulus of the cogged cordite grain to four automatic contacts fixed 45 degrees apart on the after end of the motor body.  A metal grid supports the cordite grain near the after end of the motor, and a thin metal obturator separates the grid from the venturi.  A bag of silica gel is placed in the venturi as a moisture-proofing measure.

This rocket motor must not be fired outside the temperature range of -5 to 130 degrees Fahrenheit.  Proposed new nomenclature for this motor is Motor, Rocket, 2-inch, No.4 Mk I.



Operation: Pressure of the gases from the burning cordite propellant grain passes forward into the spigot of the target head, reversing the diaphragm of the igniter.  This forces the striker into the percussion cap and ignites the gunpowder charge, which in turn initiates the flare composition.  The flare composition burns brightly, emitting light from the two sets of holes drilled in the body of the target head.









3-in Aircraft Rocket Flare (Service)
   


Flare Head
Overall length: 22.5 inches
Diameter: 5.45 inches
Total weight: 14.7 pounds
Candle power: 1,000,000
Burning time: 70 seconds
Time to primary ejection: 16 seconds
Time to light up: 19 seconds

Range to light up:
-4,800 yards when fired from ground
-5,600 yards when fire from aircraft at 140 knots



General: This head is designed for use with 3-inch A/C Rocket Motors, and may be fired either from aircraft or from ground launchers.
  


Description: The 3-inch A/C Flare Head Mk I consists of an outer body assembly and an inner canister.  The inner canister is brought to an ogive at its forward end to serve as a ballistic cap.  A parachute, enclosed in a cardboard housing, is contained in the upper portion of the inner canister.  The long cylindrical portion of the canister is then brought down inside the main body assembly, and tabs on the bottom edge of the canister are then bent over a metal lid, retaining the lid in position.  The lid consists of a metal disc, perforated in the center to accommodate the ends of two lengths of safety fuze.  A baffle plate is located between the lid and the flare candle.  Lengths of quickmatch extend from the base of the candle through the center of the baffle plate and into a gunpowder charge located between the baffle plate and the metal lid.  This charge constitutes the secondary ejection charge.  The safety fuze leading to it is the secondary delay.

A socket is fixed to the lower part of the body assembly, and to the socket is welded a spigot.  The spigot is threaded externally to screw into the shell ring of the rocket motor, and is internally threaded to receive the Ejector, Contents, No.7 Mk I.  The contents ejector consists of a threaded body, housing a diaphragm-operated striker, a percussion cap, and a double length of safety fuze, which extends into a gunpowder charge.

A base fairing is loosely assembled over the lower portion of the body assembly.  The after end of the fairing is notched to form several tabs, and a metal clip is placed around these tabs and tightened to ensure a firm attachment to the rocket motor.  The fairing serves merely to cover the joint between the flare head and the rocket motor, enhancing the streamlining of the complete round.



Operation: The pressure of the propellant gases from the rocket motor reverses the diaphragm of the contents ejector, thus firing the cap and the safety fuze in the ejector.  After the expiration of this primary delay (16 seconds)_ the primary gunpowder ejector charge is fired, expelling the inner container from the flare body assembly.  The explosion of the primary charge also ignites the secondary delay.

When the secondary delay expires, the secondary ejection charge is initiated, which ignites the lengths of quickmatch beneath the flare candle, and blows the lid out of the after end of the inner container, bending back the tabs on the base of the container.

The flare candle and the parachute assembly are now free the fall out of the after end of the container.  The flare has been ignited by the flash from the lengths of quickmatch, and is suspended in mid-air by the open parachute.  The purpose of the primary delay and ejection charge is to allow the flare ample time to lose velocity sufficiently so that an undue strain will not be placed on the parachute.

The flare head is painted black overall with a 1/2-inch red band painted around the flare body near the base.


Remarks: This flare head may be employed with the following motors: Motor, Rocket, A/C, 3-inch (Rocket Flare) Mk I; Motor, Rocket, A/C, 3-inch No.1 Mk I; or Motor, Rocket, A/C, 3-inch, No.1 Mks II-IV.









Wire-Barrage Rockets Introduction


This chapter deals with four rockets, which are designed to erect a vertical barrage consisting of parachute-supported cables, or parachute-supported wires carrying H.E. bombs.  These devices provide a temporary lethal deterrent to planes employing low-level attacks or dive-bombing tactics, and are supposed either to destroy or damage the attacking planes, or to cause them to abandon the attack.





Apparatus A.D. Type B Mk I (Obsolescent)
   

Overall length: 37 inches
Diameter: 7 inches
Total weight: 37 pounds
Propellant: Tubular cordite
Propellant weight: 3.9 pounds
Charge igniter: Magnesium (S.R. 371)
Separating charge: 154 grains G.12 gunpowder
Mine wire: 1,000 feet of steel piano wire
Bomb: H.E., A.A.D., No.2 Mk I
Bomb weight: 1 pound
Explosive: C.E. (tetryl)
Explosive weight: 8 ounces




  
General: This rocket is employed to lay a curtain of aerial mines in the path of low-level or dive-bombing aircraft attacking a ship.





Description: The tail of the rocket consists of a center tube containing the propellant charge, the gases from which emerge through the venture to propel the projectile.  The propulsive force continues for about 1.5 seconds.  Around the center tube is fitted a fairing to which are attached tail fins, protected by a cylindrical shroud.  The electric igniter leads pass through the tail fins, enter the center body of the rocket, and lead to the electric igniter.  Connected in parallel to the igniter is an electrically fired time fuze, which burns through the ignite the separating charge.  The separating charge is fired after about 10 seconds of flight time, and ejects the contents of the rocket head, which consist of the bomb, the mine wire, and the parachutes.

Operation: When the separating charge is ignited, the outer container is ejected forward from the outer case by the pressure of the exploding charge against the pressure plate.  As soon as the outer container is clear of the outer case, the pressure plate and the lid fall clear.  The lid acts as a pilot parachute and withdraws the main parachute from the container.  The main parachute opens, and, since it is connected by a spring shock absorber to the inner container, it pulls the latter clear of the outer container, which continues to fall, paying out the coiled mine wire inside it as it falls.

Also attached to the outer container is a cord, which pulls out the arming wire of the bomb as the two containers separate.  This cord subsequently breaks away to clear the wire which is being paid out.  The upper end of the mine wire is attached to the bomb and jerks it clear of the retaining-spring clip in the inner container.  The bomb is then suspended from the shock absorber by a length of light cord, termed the weak link.  This cord is secured to the shock absorber at one end, and at the other to a length of heavy cord leading from the bomb to the 7 and 1/2-inch parachute carried in the inner container. The heavy cord is thus slack between the knot and the parachute.

When all the mine wire has been paid out, the bottom bundle, containing the 30-inch parachute, is withdrawn from the outer container.  The canvas bands which protect the bundle on its way out of the container are then pulled clear by the release cord, and the bottom bundle is left hanging from the wire.  This state is accomplished about eight seconds after separation of the outer container from the rocket.

When the mine wire is struck by an aircraft, the weak link between the bomb and the shock absorber breaks, and the 7 and 1/2-inch parachute is pulled clear of the inner container and springs open.  The tautening of the wire also rips the bag of the bottom bundle, and the bottom 30-inch parachute opens.  As the aircraft pushes the wire along, the bottom parachute acts as a drogue and drags the wire across the aircraft, pulling the bomb down into contact with it.

The Bomb No.2 Mk I consists of a light sheet-steel case filled with explosive and containing a striker, detonator, and self-destroying assembly.  When the arming pin is withdrawn, the detonator is forced by its spring into alignment with the striker.  Simultaneously the delay firing pin on the detonator carrier strikes the cap and a length of safety fuze is ignited.  When the bomb strikes the aircraft, the striker is forced in and fires the detonator, exploding the bomb instantaneously.  If the wire is not struck by the aircraft, the safety fuze will burn through and detonate the bomb after about 95 seconds.  Thus the bomb is self-destructive after about 1,250 feet of fall.


Remarks: The round should ne be subjected to temperatures in excess of 110 degrees Fahrenheit.









Apparatus A.D. Type D Mk III (Service)
   

Overall length: 34.25 inches
Maximum diameter: 3.45 inches
Time to eject: 5 seconds
Lethal period: 7 seconds
Visible deterrent: 12 seconds

  
General: This rocket is designed to erect lethal wires vertically over a ship in the path of low-level or dive-bombing aircraft.  The wire is carried into the air by a rocket and is suspended by a parachute, which is carried in a container in the head of the rocket motor.  A parachute on the lower end of the wire opens when a plane strikes the wire and offers sufficient resistance to throw the aircraft momentarily out of control or to cause it to break up.  The apparatus remains lethal until its lower parachute strikes the water, about 7 seconds after ejection of the upper parachute.  It continues to act as a visible deterrent for an additional 5 seconds by which time the upper parachute has fallen to an ineffective height.




Description: The rocket consists of a tube filled with rocket-propelling composition having a conical hole down the center.  This hole is aligned with that in a choke in the after end of the tube.  A length of quickmatch and a gunpowder burster charge are located in the forward end of the tube immediately below the parachute container.  The parachute container holds the folded parachute and is closed at the forward end by a metal cap.  The parachute is connected to the forward end of the rocket motor tube.

A steel bridle and a cable are attached to the motor tube.  The cable is fitted with a loop for attachment to the main cable from the lower canister.

The lower canister consists of a cylindrical or rectangular box, which contains about 400 feet of cable.  To the lower end of the cable is attached a 38-inch drag parachute.  The forward end of the cable is attached to the cable leading from the bridle on the rocket motor.

Operation: When the projector, loaded with rocket and cartridge, is fired, the flash from the cartridge ignites the rocket propellant composition, which propels the rocket along its trajectory.  As the rocket rises, it uncoils and carries with it the main cable from the lower container, which remains fixed to the rocket projector.  When the cable is completely uncoiled, it withdraws the drag parachute from the container.  This parachute is fitted with an explosive link arrangement, allowing the parachute to open 3 seconds after firing.

When the propellant composition is completely burned out, the length of quickmatch in the head of the tube is ignited and in turn initiates the gunpowder burster charge.  This charge ejects the upper parachute from its container, leaving the rocket tube and the wire cable suspended in the air.

When an aircraft strikes the wire, the lower parachute opens and offers sufficient resistance to throw the plane out of control or to cause it to break up.








Apparatus A.D. Type J Mks I, IA, and II (Service)
   

  
General: This rocket is designed to erect a lethal wire vertically over a ship in the path of low-level or dive-bombing aircraft.  The wire acts both to bring down the aircraft if it strikes the wire, and as a visible deterrent to force the aircraft to abandon the attack.





Description: The head canister is a light cylindrical metal container, into which is packed a 62-inch parachute, called the top parachute, the cords of which are firmly secured to the base of the head canister.  A thermal fuze is fitted into the head canister and consists of a pellet of LDNR, a length of safety fuze, and 100 grains of G.12 gunpowder, which acts as an ejection charge.

The Tails, Propelling, 2-inch, Mks IVA and VA are standard 2-inch rocket motors, with a rigid stirrup welded to their after end.  No fins are fitted to the motor.  Contained within the motor body is a tubular cordite grain, into the head of which is fitted an electrical igniter.  The after end of the motor is sealed off by a light metal closing disc, through which pass the ends of the igniter leads terminating in a two-pin plug.  The proposed new nomenclature for the rocket motors is Motor, Rocket, 2-inch, No.2 Mks I and II.

The main container is a cylindrical-shaped metal container about 14 inches in diameter, with a removable lid.  Inside the container are two smaller concentric tubes, the outer of which is cone-shaped, while the inner is cylindrical.  Also encased within the main container are 825 feet of wire, a fabric bag into which is packed a 62-inch diameter parachute called the lower parachute, and a 20-inch diameter parachute called the trail parachute.

The wire is coiled down between the cone-shaped cylinder and the main container, and swivels are attached to the top and bottom ends of the wire.  The bottom swivel is shackled to the ring at the foot of the cords of the lower parachute, with the ring just protruding through the fabric bag.  Cords which keep the bag closed are connected to the trail parachute by a weak cord connection and a rip cord.  The trail parachute and fabric bag are packed into the small central cylinder, and have the swivel passing through a special slot.  The cylinder is then sealed with a light metal lid.







Operation: The rocket is fired when the attacking plane is within about 800 yards of the ship.  The wire is fully run out of 3.5 seconds after firing, and pulls the lower parachute bundle and the trail parachute up out of the inner cylinder, the lid of which is ripped off by the bottom swivel as it is pulled up.  Meanwhile, the heat from the burning cordite grain ignites the LDNR pellet in the thermal fuze, and this in turn ignites the safety fuze.  The safety fuze burns for about 6.5 seconds and then initiates the gunpowder ejection charge, blowing off the top part of the head canister and allowing the top parachute to open.  This occurs at an altitude of about 1,100 feet.  The lower parachute, still wrapped in its bag, is suspended at the bottom of the wire, and the trail parachute, which is now open, is attached to the bundle by the weak cord connection and the rip cord. 

After the top parachute opens, the wire begins to fall at about 42 ft/sec.  Twelve seconds after firing, the bottom parachute enters the water.  As soon as this occurs, the wire ceases to be lethal, but it remains a visible deterrent for an additional 12 seconds, by which time the top parachute has fallen to an ineffective height.

If the plane strikes the wire during its lethal stages, the pull on the wire breaks the weak cord connection between the lower parachute and the trail parachute.  This allows the trail parachute to pull the rip cord on the bundle, opening the fabric bag and freeing the lower parachute.  The sudden jerk caused by the wind operating on the lower and top parachutes is sufficient to throw the plane momentarily out of control, or in some cases to cause it to break up.


Remarks: The round must not be fired outside of the temperature range of 0 to 120 degrees Fahrenheit, except motors marked "S.U./K." which may be fired within the range of -5 to 130 degrees Fahrenheit.

The Apparatus Mk I differs from the Mk II in that the ceiling height of the rocket is 800 feet, and the wire is only 600 feet long.







Apparatus A.D. Type L Mks I, IA, II, and IIA (Service)
   


Canister length: 32.7 inches (approx.)
Canister diameter: 6.8 inches
Motor length: 31 inches (approx.)
Motor diameter: 2.25 inches


Use: The purpose of the Type L apparatus is to lay a curtain of aerial mines in the path of low-level or dive-bombing aircraft.





Description: The Canister Mk I consists of a conical upper container, which is connected to the tail of a 2-inch rocket motor by a short rod and a stirrup.  In the upper container are a parachute to bring down the spent motor, etc., the main support parachute, a bomb steady parachute, and the bomb.  These items are all held in position by three retaining cords, which are controlled by an explosive link.

The swivel on the lower end of the bomb is connected to the top end of a 1,000 foot coil of steel piano wire, which is contained in the lower container.  The wire from the bomb passes to the top of the coil through a slot cut in the central tube.  The central tube is provided to aid in unspooling the wire and avoid failures due to kinking.  The lower end of the 1,000 foot coil of wire passes back through the slot in the central tube and is connected to a long, light shock absorber, whose lower end is attached to the drag parachute assembly.  This latter consists of a 32-inch drag parachute housed in a bag and prevented from opening on the initial jerk at pick-up by four retaining cords controlled by an explosive link.  The junction between the upper and lower containers is effected by crimping parts of the base of the upper container lightly over the top of the lower container.

The electric leads for igniting the electric delay fuzes extend from the base of the lower container and terminate in a two-pinned plug which fits into a socket on the projector.

The Bomb, H.E., A.A.D., No.8 Mk I consists of a light sheet-steel cylinder filled with explosive.  A detonator is held in a shutter which is normally kept out of alignment with the striker by a clock spring.  An arming vane is attached to the outside of the bomb casing, and this vane, by means of a pinion wheel, is enabled to move the shutter sufficiently to align the detonator with the striker.

The Tail, Propelling, 2-inch, Mks IVB and VB consists of a slightly modified 2-inch standard rocket motor.  A closing plug is placed in the shell ring, and the electric leads terminate in a two-pin plug, which engages a socket on the projector.  The propelling unit is connected to the canister assembly by a 12-inch steel stirrup and a steel connecting rod 18 inches long.  A quick-fastening bolt is provided in the top of the canister for rapid connection to the connecting rod.  The proposed new nomenclature for the motor is Motor, Rocket, 2-inch, No.3 Mks I and II.





Operation: When the projector switch is closed, the rocket itself and the delay fuzes on the upper and lower explosive links are ignited simultaneously.  The rocket motor tows the top container into the air, and the wire is unspooled from the lower container, which remains fixed on the projector.  At the end of unspooling, the drag parachute assembly is picked up, the snatch tension being kept within safe limits by the long shock absorber.  The upper and lower explosive links are timed to operate when the container has reached a height of about 2,000 feet.

On operation of the explosive link in the top container, the bomb and parachutes are released and pulled out of the container.  Ejection of the rocket-support parachute is facilitated by a very weak cord connection between the rocket-support parachute and the main parachute.  The operation of the lower explosive link removes the constraint from the drag parachute and leaves the parachute free to open when a plane makes contact with the wire.

When a plane hits the wire, the drag parachute opens, and the weak link securing the 6-foot support parachute will part.  The bomb is pulled downwards onto the wing of the plane by the drag parachute.  When the bomb strikes the aircraft, the striker is forced downwards by the universal striker ring, firing the detonator.


Remarks: This rocket should not be fired outside of the temperature range of 0-120 degrees Fahrenheit.

The Mk II canister is identical to the Mk I except that no shock absorber is fitted, one side of the slot in the central tube is slightly flared to assist unspooling, and the length of the piano wire coil is 1,500 feet instead of 1,000 feet.











Pyrotechnic Rockets Introduction


Pyrotechnic rockets are relatively small pyrotechnic items, similar in principle to the familiar sky-rocket, which are used mainly for signaling, line-carrying, and illumination.  In most cases they are fired from a hand projector.

These items generally use a type of construction in which the head and rocket tube are integral The rocket tube is filled with a propellant composition having a tapered, conical vent hole in its center to facilitate burning.  The after end of the tube is constricted, or contains a plug of narrower diameter than the rest of the tube in order to concentrate the expanding propellant gases.  The choke and a short length of the vent tube interior are coated with gunpowder to assist in ignition of the propellant.



Kite-Launching Rocket Mk II (Service)
   

Overall length: 10.25 inches
Maximum diameter: 1.25 inches


  
General: These rockets are used to enable kites to be raised easily from emergency dinghies.  They are fired from a 1-inch signal pistol fitted with a barrel extension.
  


Description: The main rocket propellant composition is contained in the case, the nose of which is closed by a wooden plug and a layer of clay.  The after end of the case houses a plaster-of-paris choke, which is covered by a millboard washer and a paper disc.  A conical vent in the rocket propellant is aligned with a hole through the choke.  The end of the vent nearest the choke is coated with gunpowder priming.

The rocket is fixed in a bridle having a hinged stirrup, to which is attached a 2-foot wire cable.  During flight, the cable end nearest the rocket is protected from heat by an asbestos sheath.  The free end of the cable carries a loop for connection with the kite tow-line.

The rocket is painted aluminum overall, with manufacturing and filling information stencilled on the case in black letters.


Operation: When the pistol, loaded with rocket and cartridge, is fired, the flash from the cartridge ignites the gunpowder priming in the rocket, and the priming ignites the rocket propellant composition.  The rocket travels upwards for a distance of about 200 feet until the kite flying line is almost paid out.  The kite-cover retaining pins, which are attached to the kite flying line, are then withdrawn.  The kite opens automatically, and the kite cover falls away.  The flying line then withdraws a split pin connecting the rocket tow-line to the top of the kite, and the rocket is separated from the kite.









1lb Signal Rocket Mk III (Service)
   

Overall length: 16.4 inches
Maximum diameter: 1.8 inches
Total weight: 1 pound
Color of stars: White
Number of stars: 28


General: This rocket is designed for day or night signalling.


Description: The components consist of a propellant-composition filled case, closed by a wooden plug, and an upper cylinder containing 28 white stars.

The case consists of a rolled paper tube choked near the lower end to form a vent and threaded below the choke to receive the wooden plug.  The tube is filled with rocket-propellant composition, the center of which has a conical cavity.  A clay filling plug with a tapered hole in its center is located in the top of the tube, and the recess and the face of the clay are primed with mealed black powder.  A small charge of rocket composition is dusted over the top face of the clay.  A clay plug with a tapered hole is located immediately above the choke.  The recess and the choke are primed with gunpowder.  A metal socket for accommodating the stick is glued to the outside of the case, and also bound to it with twine.

The cylinder consists of a rolled paper tube filled with 28 white stars.  It is closed at one end by a paper disc covered with a paper cone, and at the other end is attached to the case.  The joints are sealed with paper strips.

The rocket is painted olive drab and carries a white instructional label around the case.  Manufacturing and filling information is stencilled on the cylinder.


Operation: When the wooden plug is removed, the vent is exposed and the rocket is ignited by applying a lighted porfire to the vent.  When the major part of the rocket composition has burned, combustion spreads through the cavity and primed hole in the clay filling to the rocket composition in the cylinder, and thereby ignites and ejects the stars.  The burning stars are ejected at a height of about 900 feet and burn for about 9 seconds.










Buoyant Line-Carrying Rocket No.2 Mk I (Service)
   

Overall length: 28 inches
Maximum diameter: 2.75 inches
Total weight: 3.25 pounds


General: This rocket is fired from a hand-firing rocket projector, and is initiated by a 30-grain percussion cartridge.  The rocket is designed for rescue purposes on marine craft and for use by airfields situated in coastal areas as a means of contacting crews of aircraft which have crashed into the sea immediately after take-off.


Description: The rocket consists of a wooden head made in two halves, held together with screws, which engage the head of the rocket tube.  The rocket propellant composition is contained in the tube, the nose end of which is closed by a wooden plug and a clay plug.  The after end of the rocket tube houses a plaster-of-paris choke, which is covered by a millboard washer and an oiled paper disc.  A conical vent is formed in the rocket propellant composition in line with a  tapered hole in the choke.  The end of the vent nearest the choke and the hole in the choke are coated with gunpowder priming.

A bridle with a hinged stirrup is attached to the rocket, and a tail consisting of a wire cable about 3 feet long is secured to the stirrup.  The part of the tail nearest the rocket is protected from the heat of the burning rocket composition by an asbestos sheath.  The free end of the tail carries a loop for connecting to a buoyant line.

The buoyant line consists of 250 yards of orange colored cotton cord, which is specially treated so that it will float on water.  It is coiled in a square cardboard container whose lid is secured by adhesive tape.

The wooden head is painted yellow overall and filling and manufacturing information is stencilled on the head in black letters.


Operation: When the projector, loaded with rocket and cartridge, is fired, the flash from the cartridge ignites the gunpowder priming in the rocket and at the same time forces the rocket out of the projector.  The gunpowder priming ignites the rocket composition, which then takes over and propels the rocket along its trajectory.  The rocket draws the buoyant line out of its container, and, when expended, falls into the sea and floats on the surface.










3 and 3/4lb Illuminating Rocket No.2 Mk I (Service)
   

Overall length: 30 inches
Maximum diameter: 2.25 inches
Total weight: 3.75 pounds
Height of ejection: 750 feet
Burning time: 45 seconds
Candlepower: 180,000


  
General: This rocket is currently employed only by the Air/Sea Rescue Service to assist in sea rescue searches at night.  It is fired from a hand-firing projector, and is initiated by a 30-grain percussion cartridge.


Description: The rocket consists of a steel rocket tube containing a rocket-propelling composition, which has a conical cavity in the center.  The rocket tube is fitted at one end with a metal center.  The rocket tube is fitted at one end with a metal flare container housing a wooden plug, a flare candle, and a cotton parasheet attached to the candle by a wire strap.  Crimped into the other end of the tube is a wooden choke sealed by a paper disc.

Secured to the rocket tube is a steel bridle, which extends beyond the wooden choke and carries a hinged stirrup.  One end of a steel rope tail is screwed to the base of the stirrup.  The end of the tail is protected from the heat of the burning propellant composition by an asbestos sheath.  The other end of the tail is spliced to form a loop to which is attached a 12-foot hemp rope.  The rope is coiled into a paper envelope, which has a cotton loop attached to it.  The envelope, with the rope inside, is attached to the rocket by a rubber band when supplied.

The wooden plug in the flare container carries a recess which houses a small quantity of gunpowder and a length of quickmatch.  The quickmatch contacts both the gunpowder and the rocket composition.

The flare candle consists of a cardboard cylinder held in place in the flare container with cotton-wool packing, and closed at one end by a wooden block.  This block has a pin passing through it to take one end of the wire strap of the parasheet.  At the other end of the cardboard cylinder is secured a washer, housing a gunpowder charge which is held in place by a muslin disc.  Above this disc is placed a small amount of priming composition.  An illuminating composition fills the remainder of the candle.

The parasheet and the wire strap are packed into the flare container with packing cylinders, and the container is closed by a metal lid secured with adhesive tape.

The flare container is painted aluminum overall.  The filling and manufacturing information is stencilled on the container in black letters.


Operation: When the projector, loaded with rocket and cartridge, is fired, the explosion of the cartridge breaks the paper disc, and the flash passes through the choke and ignites the rocket-propellant composition.  The gases generated by the composition then take over and force the rocket along its trajectory.  When the rocket composition is almost burned through, it ignites the quickmatch.  The flash from the quickmatch initiates the gunpowder in the wooden block.  The flash from the gunpowder ignites the priming composition in the flare candle, which in turn fires the illuminating composition.  Simultaneously, the pressure of the gases from the exploding gunpowder forces the lid from the flare container, and ejects the ignited candle and its attached parachute.  The tail and the hemp rope act as flight stabilizers.









6 and 1/4lb Illuminating Rocket No.1 Mk I (Service)
   

Overall length: 22.5 inches
Maximum diameter: 3.5 inches
Total weight: 6.25 pounds
Height of ejection: 800 feet (approx.)
Burning time: 45 seconds (approx.)
Candlepower: 300,000


General: This rocket is currently used by the Royal Observer Corps to indicate the presence of low-flying enemy aircraft to patrolling fighters, and by the Air/Sea Rescue Service to assist in sea rescure searches at night.  The rocket is fired from a Type B Rocket Projector, Mk III or IV, using a 60-grain percussion cartridge.


Description: The rocket consists of a rocket tube, a sliding tail, and a flare container, which houses a burster charge, flare candle, and parachute.  The rocket tube is filled with a rocket propellant composition, having a conical cavity in the center, and is closed at one end by a gun-metal choke crimped in position.  The choke is closed by a paper seal.  At the other end of the rocket tube are a wooden block and a clay plug, with a hole to receive a length of quickmatch.  The flare container is crimped to a metal junction head secured by screws to the wooden block.  Housed in the junction head are a wooden washer, covered with primed cambric, and the burster charge, which is held in place by another wooden washer.

The flare candle consist of a rolled paper case, strengthened at one end by a tin-plate cup, and held in place by felt packing.  The strengthened end of the case contains a fusible metal cup having a central hole.  This cup houses a quantity of priming composition, which is held in place by a primed cambric disc and a paper washer.  The main illuminating composition of the candle is held in place by a millboard disc.  A suspension cup, riveted to the paper case, carries a piece of wire wrapped at both ends with adhesive tape.  One end of a wire strap is looped around the middle of the wire.  The other end of the wire strap is attached to a 36-inch parachute, which is packed into the flare container between a wooden washer, millboard spacers, and a wooden disc.  The top of the flare container is closed by a metal lid secured in place with adhesive tape.

The sliding tail is of the drum type.  When the rocket is fired, the tail slides along the rocket tube until arrested by the metal choke.  A leaf spring attached to one of the tail fins then holds the tail in the extended position.

The flare container is painted aluminum overall, with filling and manufacturing information stencilled on the container in black letters.


Operation: When the projector, loaded with rocket and cartridge, is fired, the explosion of the cartridge breaks the paper seal on the rocket choke, and the flash passes through the choke to ignite the rocket-propellant composition.  The gases generated by the burning propellant then carry the rocket along its trajectory.  When the rocket composition is almost burned through, it ignites the quickmatch and the primed cambric, which in turn fires the burster charge.  The flash from the burster charge ignites the flare candle and forces the lid from the flare container, ejecting the ignited candle and its attached parachute.









9lb Illuminating Rocket Mk II (Service)
   

Overall length: 36 inches
Maximum diameter: 6 inches
Total weight: 9 pounds
Height of ejection: 1500 feet (approx.)
Burning time: 60-70 seconds
Candlepower: 300,000

  
General: This rocket is currently used only by the Royal Observer Corps to indicate to patrolling fighters the presence of low-flying enemy aircraft.  The rocket is fired from a Type B Rocket Projector Mk IV, using a 60-grain percussion cartridge.


Description: The rocket consists of a steel rocket tube, a tail, and a metal flare container, which houses a parachute, flare candle, and burster charge.  The rocket tube is filled with a propellant composition, with a conical cavity in the center.  At one end of the rocket tube is a gun-metal choke crimped in position and closed with a paper disc.

At the other end of the steel tube is a clay plug provided with a flash hole.  The flare container is fastened with screws to a metal junction head, which houses the burster charge and a length of quickmatch.  The burster charge is held in position by a wooden washer, covered with primed cambric.  Attached to the flare container is a waterproof sleeve, which fits over the projector barrel to prevent rain from entering the barrel when the projector is loaded.

The flare candle consists of a rolled paper case, strengthened at one end by a tin-plate cap and held in place with felt packing.  The strengthened end of the cap contains a fusible metal cup having a central hole.  Housed in this cup are a quantity of gunpowder, priming composition, and two igniter pellets.  The gunpowder and priming composition are held in place by a muslin disc.

The main illuminating filling of the candle is pressed in position and held in place by a millboard disc.  A wooden block, resting on the millboard disc, has a central hole to receive one end of a wire strap, which is lopped around a metal rod passing through the wooden block.  The block is riveted to the paper case.  The other end of the wire strap is attached to a 36-inch parachute, packed in the flare container between a wooden washer, cardboard spacers, and a wooden disc.  The top of the flare container is closed by a metal lid secured to the container with adhesive tape.

The rocket is stabilized in flight by a tail secured to the rocket tube.  The tail consist of four fins attached to a bridle, which is fitted to the rocket tube.

The flare container is painted aluminum overall, with filling and manufacturing information stencilled on the container in black letters.


Operation: When the projector, loaded with rocket and cartridge, is fired, the flash from the cartridge breaks the paper sealing disc, passes through the choke and ignites the rocket-propellant composition, which then forces the rocket along its trajectory.  When the rocket composition is almost burned through, the flame passes through the flash hole and ignites the length of quickmatch and the burster charge.  The flash from the burster charge ignites the flare candle and forces the lid from the flare container, ejecting the ignited candle and its attached parachute.





Next Time: Hand, Rifle, and Anti-Tank Grenades

Monday, 16 January 2017

British Explosive Ordnance - Obsolete Bombs








British Explosive Ordnance







Obsolete Bombs Introduction


The various bombs of different types included in this section have all been declared obsolete, but because of the possibility that they still may be encountered, it is deemed desirable to give complete information regarding them.

Older obsolete bombs, included only as a matter of interest, are listed in chart form at the end of the chapter.









AT 9lb, Mk I  (Obsolete)

Overall length: 14 inches
Maximum body diameter: 4 and 1/2 inches squared
Total weight: 8.5 pounds
Charge/weight ratio: 80%

Fuzing: Tail Fuze No.847
  

Color and markings:  Dark green overall,
1/2-inch red band around nose.

  
Body Construction: The body is made of thin metal, approximately rectangular in shape, having a square cross section with rounded corners.  It tapers slightly from the rear toward the nose.  The body is closed at the nose end by a front cover housing a nose cup, which is taped and cemented in place.  The nose cup of the rear bomb forms a safety device for the fuze in the front bomb of a pair, as bombs are dropped in pairs.  The rear cover is located approximately in the middle of the bomb.  The bomb incorporates a steel, cone-shaped charge.


Tail Construction: The tail is integral with the body, being only a continuation of the thin metal case.  The rear bomb of a pair has a retarder plate to pull the rear bomb free of the front one when dropped from the container.  The tail also has a safety tube of light-gauge metal with a  cardboard inner sleeve, forming a safety device for the fuze of the rear bomb of a pair.  A locating plate near the rear of the safety tube locates the tube in the tail of the bomb.

 
Suspension: These bombs are carried in the 250lb Small Bomb Container, which holds 24 bombs.  They are loaded in pairs, with the nose of the rear bomb houses in the tail of the front bomb.


Filling:
-Exploder: CE pellet housed in the bottom of the exploder container
-Filling: Nobel's explosive No.808, with shaped charge effect.


Remarks: The bomb is designed for use against tanks and armored vehicles.  It will blow a hole approximately nine inches in diameter in armor plating 2 inches thick, and is effecting at striking angles up to 45 degrees.

The 9lb AT Practice Bomb Mk I is approximately the same shape, size, and filled weight, and has the same approximate ballistic characteristics.  However, it has neither exploder nor detonator.  Its body breaks up on impact with the target to release a white filling, clearly visible from the air.








HE 20lb Mk I (Obsolete)

   
Overall length: 25 inches
Body length (w/o tail adapter): 11 inches (approx.)
Body diameter: 5.175 inches
Tail length (w/ tail adapter): 12 inches (approx.)
Tail width: 6 inches (approx.)
Total weight: 27 pounds (approx.)
Charge/weight ratio: 20% (approx.)

Fuzing: Nose Pistol No.16
  

Color and markings:  Dark green overall,
1/2-inch red band and 1 inch light green band around nose.

  
Body Construction: The bomb has a steel, semi-steel or malleable-iron body, hollow and open at both ends, with the forward end threaded internally to receive the nose adapter, and the after end internally threaded to take the tail adapter.  The nose adapter has three different-sized threads, to take the detonator-holder and the exploder container from the rear,a nd the pistol from the front.  The flange of the nose adapter is externally threaded to receive a screw-on pistol cover.  The tail adapter is tapered to conform to the rearward streamlining of the body, with a central bore threaded to receive the tail rod.


Tail Construction: The bomb has a wooden tail cone, conforming to the streamlined shape of the body.  Two diametrical saw-cuts at right angles extend from the after end, over a slightly greater length than that of the tail vanes, to accommodate the four sheet-metal tail vanes, which are made in integral pairs.  The tail cone is bored axially to take the tail rod, and fits into the cavity in the tail adapter.


Suspension: A wrought-iron or mild steel suspension lug is riveted to the bomb body.


Filling:
-Exploder: 3 sold and 1 perforate CE pellets.
-Filling: 5 pounds (approx.) TNT


Remarks: This bomb was intended for attacking personnel, air strips, and road transports.







RL 112lb Mks V, VI, and VIII (Obsolete)
   
   
Overall length: 18 inches
Body diameter: 8 inches
Wall thickness: Solid body
Total weight: 10 pounds

Fuzing: Nose Pistol No. 8 Mk I, or Nose Pistol No.19 Mks I and II; Tail Pistol No.5B Mks I and II
  

Color and markings: Yellow overall,
1/2 inch red band around nose,
1 inch light green band around body.

  
Body Construction: The body of these bombs is a single streamlined casting, steel for Mks V and VII and iron for Mk VI, threaded at the nose and tail to take adapters for the central exploder tube.


Tail Construction:
Mk V: The tail of the Bomb Mk V consists of four tail fins, which fit over the body and are fastened in place with screws.  Two sets of box-type struts reinforce the tail fins.


Mks VI and VII: The tail assembly of the Bombs Mk VI and Mk VII consists of a tail cone, which slides over the after end of the bomb body and sis secured by a locknut on the exploder tube.  Four tail fins are riveted on the cone and are held in place by two sets of box-type struts.


Suspension: The Bomb Mk V has a U-shaped eye-bolt secured to the body with screws at the center of gravity.

The Bombs Mk VI and Mk VII have a U-shaped eye-bolt fastened to a suspension band around the center of gravity.


Filling:
-Exploder: TNT and CE pellets
-Filling: Amatol 80/20, or TNT
  






GP 120lb Mks I and II (Obsolete)
     

Overall length: 42.4 inches
Body length: 21.5 inches
Body diameter: 8.1 inches
Wall thickness: 0.5 inches
Tail length: 15.7 inches
Tail width: 8 inches
Total weight: 120 pounds (Amatol 80/20)
Charge/weight ratio: 25%

Fuzing: Nose Pistol No.19; Tail Pistol No.21
  

Color and markings:  Yellow overall,
1/2-inch red band around nose and 1 inch light green band around body,
longitudinal green bar on body and tail indicates explodering scheme..

  
Body Construction: The body is a streamlined steel casting or forging, threaded at the nose to take the nose adapter, which holds the central exploder tube.  At the other end of the casting is a threaded base plug through which the exploder tube passes.  Welded to the end of the casting is a streamlined section of thin metal, containing no explosive, which is tapered to take the tail ring.  The exploder passes through this section also.


Tail Construction: A truncated cone fits over the rear section of body and is held to it by a locknut over the exploder tube.  Three mild-steel fins are fastened to the cone, and are reinforced by a cylindrical strut.


Suspension: The bomb uses a single suspension lug secured to the body by four screws.


Filling:
-Exploder: TNT and CE pellets
-Filling: 36.5 pounds TNT, or 30 pounds Amatol 80/20


 






GP 500lb Mks I, II and III (Obsolete)
     


Overall length: 68.7 inches
Body length: 35.7 inches
Body diameter: 13 inches
Wall thickness: 7/8 inches
Tail width: 13 inches
Total weight: 509 pounds (TNT)
Charge/weight ratio: 28%

Fuzing: Nose Pistol No.19; Tail Pistol No.17 or 22
Tail No.: No.1 Mk I (Mk III bomb only)
  

Color and markings:  Yellow overall,
1/2-inch red band around nose and 1 inch light green band around body,
light green bar on body and tail indicates explodering scheme..

  
Body Construction: The body is a streamlined steel casting or forging threaded at the nose to take the nose adapter, which holds the central exploder tube.  At the opposite end is a threaded base plug through which the exploder tube passes.  Welded to the after end of the body is a streamlined cone of thin metal, containing no explosive, which is tapered to take the tail ring.  The exploder also passes through this section.


Tail Construction: The tail has a truncated cone, which fits over the rear section of the body and is held to it by a locknut over the exploder tube.  Four mild-steel fins are fastened to the cone, and are reinforced by a cylindrical strut.


Suspension: The bomb is suspended by a single suspension lug secured to the body by four screws.


Filling:
-Exploder: TNT and CE pellets
-Filling: 143 pounds TNT, or 134 pounds Amatol 80/20


Remarks: The tail fins are usually painted red when time pistols are used.








HC 2000lb Mk I (Obsolete)

   
Overall length: 162 inches
Body length: 99.5 inches
Body diameter: 18.5 inches
Wall thickness: 0.19 inches
Tail length: 60 inches
Tail width: 18.6 inches
Total weight: 1842 pounds
Charge/Weight ratio: 73%

Fuzing: Nose Pistol No.27, 42, or 44
Tail No.: No.32 Mk I, or No.10 Mk I or II, or Parachute Attachment
  

Color and markings: Dark green overall,
1/2-inch red band 3 and 1/2 inches from front edge of cylindrical shell,
2-inch light green band 16 inches from edge.


Body Construction: The body consists of a cylindrical steel shell with a hollow, conical nose piece welded to one end, parallel sides, and a closing plate bolted to an angle ring which is welded in position a short distance within the other end.  A radial strengthening band is welded internally at the center of gravity, and its ends are welded to a steel block.  Holes tapped through the shell and steel block receive the suspension lug screws.  Side pockets for supplementary fuzing are present near the base end, but are not used.  The shell is strengthened longitudinally by two channel beams welded to each end of a central steel block and to the shell interior.


Tail Construction: The Tail No.32 Mk I assembly consists of a cylinder of light-gauge metal with a metal tray secured in its forward end and a strengthening ring in its open rear end.  The tray has a series of equispaced bayonet dogs for attaching to the body bayonet joints welded to it.  The cylinder has a number of openings to give it stability.

The parachute attachment has a parachute 5 feet, 6 inches in diameter, attached to a metal tray having bayonet dogs for attaching it to the body.  The parachute is retained by waterproofed fabric and a retaining pin.  The retaining pin is attached to a static cord stitched on the outside of the last protective panel, and connected to the bomb carrier or aircraft.  On release the cord pulls the retaining pin and chute free, and breaks off from the plane when the chute is extended.
 

Suspension: The bomb is suspended by a single suspension lug bolted to the body and an internal steel block at the center of gravity.  The screw holes are closed by transit screws until the bomb is to be used, at which time the lug is attached.
  

Explosive Components:
Exploders: A central exploder tube extends from the nose exploder container.  The tube contains eight 33 and 1/4 ounce TNT exploders.  The exploder container contains a 9 ounce TNT exploder.

Filling: 1340lb Amatol 60/40 sealed at each end with an approved composition


Remarks: This bomb may be fitted with a nose attachment of light-gauge metal to retard the bomb in flight.  It consists of a cylinder fitting over the forward end of the body shell and projecting forward beyond it around the conical nose piece.  Two side fuzing pockets are usually not used, but might contain the Time Pistol No.47.






 




AS 35lb Mks I and II (Obsolete)


Overall length: 29.2 inches
Body length: 17.2 inches
Body diameter: 7 inches
Wall thickness: 0.064 inches
Tail length: 17 inches (approx.)
Tail width: 7 inches
Total weight: 35 pounds
Charge/Weight ratio: 46%

Fuzing: Nose Fuze No.866
  

Color and markings: Dark green overall,
1/2-inch red band and 1-inch light green band around body.


Body Construction: The bomb has parallel sides, with a nose adapter and a tapered rear section.  A tail adapter secures the tail to the body.  The explosive charge is cone shaped, employing the principle of Munroe shaped charge.  A cylindrical nose attachment is welded onto the nose adapter by four tack welds.  The exploder is in the rear of the body, and is initiated by a flash from the nose fuze, communicated through the supporting tube extending from the nose cavity to the exploder.


Tail Construction: The tail consists of a long hollow tube with a cylindrical strut attached to it by six fins.  The tail threads into the tail adapter, and is secured by a locking screw.  The six fins are formed by three sets of W-shaped supports welded to the tail tube.
 
Suspension: The Bomb Mk I has a single lug for suspension in aircraft.  The Mk II has no lug, as it is intended to be fired from shipboard.
  

Explosive Components:
Exploder: CE pellets
Filling: 16lb RDX/TNT 60/40.  The after end is sealed by a 1/4-inch topping of TNT.

Remarks: The Bomb Mk I was designed for use by Coastal Command and was intended to be dropped from aircraft.  The Bomb Mk II has no suspension lug, and is intended for spigot projection from ships.



 






DC 450lb Mk VII (Obsolete)


Overall length: 67.25 inches
Body length: 27.75 inches
Body diameter: 17.5 inches
Tail length: 32 inches (approx.)
Tail width: 17.5 inches
Total weight: 450 pounds
Charge/weight ratio: 64%

Fuzing: Mk X** pistol and depth adjuster
  

Color and markings: Dark green overall with circumferential red and green bands


Body Construction: The body consists of a welded cylindrical case, closed by two covers connected by a central tube called the primer tube.  This tube, housing the primer, pistol, and depth adjuster, has an internal diameter of 3.5 inches.  Three lifting eyes with rings are provided, one on the cover at the primer end, and two on the cover at the opposite end.  The cover at the primer end has two filling holes which are closed by bungs.  It may or may not have a nose attachment and tail.  The bomb is carried on aircraft with the primer end forward, except when fitted with the parachute attachment, in which case the pistol and depth adjuster are forward.


Nose Attachment: The bomb may use a hemispherical hollow nose held on by the side straps, which also secure the tail assembly.


Tail Construction: The tail, when fitted, consists of a cylindrical strut attached to a hollow tail cone by four fins.  Three brackets, equispaced around the cone, are fitted to take the ends of the straps which secure the nose and tail attachments, both of which break off on impact with water.  The bomb may have a parachute attachment on the primer end if dropped from high-speed aircraft.

 
Suspension: The bomb is suspended by a single lug on a suspension band around the center of gravity.


Explosive Components:
Filling: 290lb Amatol









IB 25lb Mks I and II (Obsolete)


Overall length: 32.6 inches
Body diameter: 5.03 inches
Tail length: 13.55 inches
Total weight: 25 pounds

Fuzing: Simple impact striker
  

Color and markings: Dull red overall,
two 1/2-inch black bands separated by 1/2-inch red band painted around the nose.


Description: The Bomb Mk I consists of a cylindrical steel tube secured to a hollow, sharp-pointed nose by a nose adapter (built up externally to streamlined form by a cardboard fairing), a column of seven closed containers, termed fire-pots, accommodated in the body tube, a flanged base adapter which affords a mounting for a cap holder, a tail cone with a cylindrical tail vane secured to it by four vane supports, and a tail tube which accommodates a striker pellet, with a shear wire and creep spring, and a safety rod.

Each of the seven fire-pots consists of a cylindrical container made of magnesium alloy and formed with a central tube, which communicates, through a fire hole, with a recess in a central boss on the base of the container.  The container is closed by a magnesium alloy lid, which has a shallow central recess in its outer side.  Holes through he lid place this recess in communication with the interior of the container.  The ignition cap contains a layer of gunpowder and a layer of detonating composition.

The central tube of each of the fire-pots houses a delay charge and is surrounded by a delay charge and a priming charge for the thermite and magnesium filling, which occupies the remainder of the annular chamber in the fire-pot.  A loop of quickmatch extends into the bore of the central tube and has its two ends carried out through the slots in the tube and through two of the holes in the lid.  An ejection charge of gunpowder is retained in the recess in a central boss of each fire-pot by a paper disc, which is secured in position by shellac.

The tail cone fits over the flange of the base adapter and is held assembled to the bomb body by a tail nut, which screws onto the rear end of the tail tube against a tail adapter.  The tail adapter fits into the rear end of the tail cone.

The striker pellet has a sharp point at the forward end and is held in the safe position by a shear wire passed through holes in the striker pellet and tail tube.  The ends of the shear wire are soldered to prevent removal.  The rear end of the striker pellet receives the forward threaded end of the safety rod.  The creep spring is house in the forward end of the tail tube and bears against the cap holder and the striker pellet.  The safety rod passes through the tail tube and is screwed into the threaded bore of the striker pellet.

The Bomb Mk II has only a slight difference in the tail plate.


Parachute Attachment: Either a Parachute Attachment No.1 Mk I or a No.1 Mk II may be used with this bomb.  The Attachment No.1 Mk I consists of a small parachute housed in a container of sheet metal, consisting of a cylindrical housing plate and a cover.  It fits loosely in the cylindrical strut of the bomb tail.  The chute is 15 inches in diameter and vented at the peak.  The Attachment No.1 Mk II is similar, except that it is housed in a collapsible cardboard container between cardboard packing discs.


Striker Attachment: There are two striker attachments, the No.1 Mk I, and the No.1 Mk II.  No.1 Mk I consists of a coupling fork, snatch rod, striker rod, coupling socket, and a retaining sleeve, which houses a spring.  The No.1 Mk II is similar, except that the coupling fork is fitted with a quick-release pin.


Functioning: Whent he bomb using the Parachute and Striker Attachments No.1 Mk I is released, the cover pulls the chute out.  The chute opens and pulls the snatch rod against the action of the spring until the striker rod retaining balls escape into the annular recess in the retaining sleeve.  The striker rod then moves down against the striker pellet.  On impact, the inertia of the rod and pellet combine to shear the shear wire, overcome the creep spring, and pierce the ignition cap, igniting the blowing charge and blowing the base adapter and complete tail and parachute assembly from the body tube.  The quickmatch, which passes through the lid and into the central tube of the rearmost magnesium alloy fire-pot, is also ignited, and, in turn, the quickmatch ignites the delay charges in and around the central tube of the fire-pot.

While the central tube delay charge is burning through, the outer delay charge initiates the surrounding priming charge, which, in turn, ignites the incendiary composition around it.  Meanwhile, the central delay charge burns through and fires the ejection charge in the base of the fire-pot.  This has the effect of ejecting the activated fire-pot from the bomb and also igniting the quickmatch of the second fire-pot, etc.  Each ejected fire-pot will continue to burn for approximately 10 minutes; the magnesium alloy container and lid being consumed.

Finally, the quickmatch in the lod closing the nose of the bomb is ignited by the last ejection charge and initiates the priming charge, which, in turn, ignites the incendiary composition of the nose, and provides an additional fire source.

When used with the Parachute and Striker Attachment No.1 Mk II, the parachute is blown out of the cylindrical shroud on the tail and the chute opens, freeing the striker mechanism.  Functioning after this is the same as that with Attachments No.1 Mk I.

Suspension: The bombs may be carried in a Small Bomb Container, or from a bomb carrier by a lug on a suspension band.


Explosive Components:
Filling: 1lb Thermite, and 5lb, 4oz Magnesium







IB 250lb Mks I and II (Obsolete)



Overall length (w/o fuze): 61 inches (approx.)
Body length: 34.1 inches
Body diameter: 12 inches
Tail length: 27.2 inches
Tail width: 11.7 inches
Fuel weight: 68 pounds
Total weight: 193 pounds

Fuzing: Nose Fuze No.36 Mk II with Ejector Charge No.2 Mk I
Tail No.: No.1 Mk I
  

Color and markings: Red overall,
two 2-inch black bands separated by a 2-inch bright red band near nose.


Description: The bomb has a cylindrical body with a hemispherical nose and parallel sides.  An ejector-charge container is screwed and cemented into the nose and takes the nose fuze.  The tail consists of a tail cone and a cylindrical strut attached to the cone by four fins.  The after end of the body is closed by a tail plate, which is lightly secured to the body.


Functioning: On impact, the fuze functions and ignites the gunpowder ejection charge, which in turn ignites the incendiary filling and ejects it with the tail and tail plate.


Suspension: The bomb is suspended by a single suspension lug.


Filling: The Bomb Mk I is filled with a phosphorus-rubber-benzene mixture.  The Bomb Mk II is filled with a "sticky flammable liquid."  The ejector charge consists of black powder.


Remarks: This bomb was intended primarily for attacking forested areas, and can be dropped from heights up to 8,000 feet.
















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