Monday, 9 January 2017

British Explosive Ordnance - Practice, Infantry Training, and Miscellaneous Bombs

British Explosive Ordnance

Practice Bombs Introduction

Included in this section are five sizes of practice bombs.  These are the only ones specifically designed for that purpose, although there are currently in use several practice bombs which are merely service bombs inert-loaded with sand, water, or a chalk/lime solution.  The standard practice bombs generally emit smoke as a spotting charge to indicate bombing accuracy.

Standard practice bombs are painted white overall with two light green bands painted around the center of the tail.  Inert-loaded service bombs used as practice are painted black.  Practice bombs containing an exploder have a red band painted around the rear portion of the body.

Practice 8lb, Mk I  (Service)

Overall length: 16 inches
Maximum body diameter: 4 inches
Total weight: 8 pounds (approx.)

Fuzing: None

Color and markings:  White overall,
two 1/2-inch green bands around after body.

Body Construction: The body consists of an asbestos cement cylinder, in the nose of which is cemented a glass flask containing about 1/2 pint of titanium tetrachloride.  The rear of the cylinder is hollow and acts as a tail unit.  A light metal suspension band is secured to the exterior of the bomb body.

Functioning: On impact, the bomb body and glass flask break up, releasing the titanium tetrachloride to form a smoke cloud.  The bomb contains no explosive.

Remarks: The bomb is designed for low-level training purposes against airfield targets, and is of such construction that it leaves no debris injurious to aircraft tires.

Practice 8.5lb Mks I, II, and III  (Service)

Overall length: 16 inches
Body length: 12 inches
Body diameter: 3 inches
Wall thickness: 0.5 inches
Tail length: 4 inches
Tail width: 3 inches
Total weight: 8.5 pounds

Fuzing: Integral simple impact arrangement with detonator burster No.28 Mk I

Color and markings:  White overall,
two 1/2-inch green bands 1/2 inches apart around after body.

Body Construction: The Bombs Mk I and Mk III have a molded plastic body, which is made in three parts: a nose section housing the striker, a center section housing the detonator burster and filling plug, and a rear section which is hollow and closed at the after end.  A perforated disc inside the rear section supports the end of the detonator burster holder.  The center part of the body is filled with lead-antimony balls, with the interstices between them, and all but a 10% air space in the rear section cone, filled with titanium tetrachloride, or gunpowder and magnesium turnings.

The striker head is retained in handling by a cotter pin, safety pin, and shear wire.  An annular groove inside the nose portion is filled with lead shot secured by wax.

The Bomb Mk II nose is fitted for an extension rod.

Tail Construction: The tail assembly consists of a tube molded into the rear section of the body, with a cylindrical strut attached to the tube by four fins.

Suspension: The bomb is suspended by a single suspension lug on a band, which fits in a groove in the body, and is secured in place by a securing screw.

Filling: Main filling:
Bombs Mk I and Mk II contain titanium tetrachloride, which, when exposed to the atmosphere, forms a cloud of white smoke, marking the point of impact.  The Bomb Mk III has a flash filling consisting of gunpowder, and magnesium turnings.

Remarks: This bomb is designed for use against certain targets where a bomb is required to break on impact without causing damage to the target.  Because of its low terminal velocity, the bomb is only suitable for low-altitude bombing.

The Bombs Mk I and Mk II have smoke charges for day use, while the Mk III has a flash filling for night use.

Practice 10lb Mk I (Service), Mk II (Obsolete), and Mk III (Service)

Overall length: 18 inches
Body diameter: 8 inches
Wall thickness: Solid body
Total weight: 10 pounds

Fuzing: Integral simple impact arrangement with detonator burster No.28 Mk I

Color and markings:  White overall,
two light green bands 1/2 inches wide around tail cone.

Body Construction: The bomb has a solid cast-iron nose with an axial bore housing the striker head and rod, with a guide bush threaded into the rear cavity, and integral rear threads to take the central plug.  The striker is retained by a cotter pin (removed when loaded on aircraft), safety pin, and shear wire extending through the striker rod and guide bush.  The central plug houses the central burster tube.

Tail Construction: The tail cone is closed at the rear by a conical tail plug, and at the front end by the central plug to which it is attached.  The central tube extends through the tail cone to the tail plug, and holds the detonator burster.  A tapped hole, fitted with a plug, is provided in the central plug for filling.  The tail tube, with four fins carrying a cylindrical strut, projects from the tail plug.  Its rear end is closed by a cap.

Suspension: The bomb is suspended by a single eyebolt, which screws into the bomb body opposite the cavity for suspension from a Light Series bomb carrier.

-Smoke filling: Mk I: 1lb Titanium Tetrachloride, which forms a white cloud on exposure to atmosphere.
-Flash Filling: Mk III: 1lb mixture of gunpowder and magnesium turnings, which causes a brilliant white flash on detonation.

Remarks: The Bomb Mk I with its smoke filling is used for daytime practice operations.  The Bomb Mk III with its flash filling is used at night.  These bombs, because of the solid iron nose, should not be used against lightly armored targets.

Mk II had a plastic tail, but was not 'satisfactory'. so all were scrapped.


Practice 11.5lb Mk I (Service), and Mk II (Obsolete)

Overall length: 18 inches
Body diameter: 3 inches
Tail width: 3 inches
Total weight: 11.5 pounds

Fuzing: Integral simple impact arrangement with detonator burster No.28 Mk I

Color and markings:  White overall,
two 1/2-inch light green bands 1/2-inch apart around after body.

Description: The bomb consists of a nose casting, fitted with a striker assembly and a tail cone which constitutes a container for the filling, and is fitted with a central tube for a detonator burster.  The nose casting is made of iron, internally threaded at the rear to receive the spigot portion of a central plug which closes the forward end of the tail cone.  The interior of the nose is filled with lead, and has a clearance hole for the striker rod.  The striker is secured by a cotter pin (removed when loaded), a safety pin spring-loaded outward, and a shear wire through the guide brush.

Tail Construction: The sheet-metal tail cone, constituting the container for the filling, is closed at the rear by a conical steel tail plug and at the forward end by a central plug which screws into the rear of the nose casting.  A tapped hole is provided in the central plug for filling purposes.  Secured to the tail plug is a tail tube having four fins, which carry a cylindrical strut.  The tail tube is closed at the rear by a cap.

Suspension: The bomb is suspended by a single eyebolt, which threads into the bomb case.

-Smoke filling: Mk I: 1lb Titanium Tetrachloride, which produces white smoke when the detonator burster breaks open the tail cone and exposes it to the atmosphere.
-Flash Filling: Mk III: 1lb mixture of gunpowder and magnesium turnings, producing a brilliant white flash on impact.

Remarks: The Bomb Mk I with smoke filling is used for daytime practice.  The flash-filled Mk I is used at night.

The Bomb Mk II is made in the US of bakelite, but have now been scrapped.

Practice 25lb Mks I and III (Obsolete), and Mks IV and V (Service)

Overall length: 22 inches
Body diameter: 4 inches
Total weight: 25 pounds (approx.)

Fuzing: Integral simple impact arrangement with detonator burster No.28 Mk I

Color and markings:  White overall,
Mk I has two 1/2-inch green bands on after body,
Mk III has two 1/2-inch black bands on after body, and one red band on nose.

Description: This bomb consists of a solid, cast-iron nose section bored centrally to house a striker head, to which are attached a long striker rod and striker.  A striker guide bush is threaded into the after end of the central bore.  A shear wire through the guide bush and the striker prevents the striker from contact with the detonator burster in the unarmed position.  During transit and normal handling, the striker also is retained by a split pin and a spring-loaded safety pin.  The split pin is removed when the bomb is loaded aboard the plane, and the safety pin is ejected when the bomb is released.

Tail Construction: The tail consists of a long tail cone, closed at the wider end by a central plug.  A central tube for the detonator burster passes through the tail cone.  Located in the central plug, slightly off-centre, is a filling pug through which the smoke or flash filling is inserted.  As in most British practice bombs, the filling is contained in what is actually a part of the tail portion of the bomb.  A tail tube is attached to the after end of the tail cone and supports a cylindrical shroud and four fins.  The central plug is threaded externally and screws into the after end of the cast iron nose section of the bomb.

Suspension: A single U-shaped suspension lug is provided to suspend this bomb.

-Smoke filling: Mk I and Mk IV - Titanium Tetrachloride
-Flash Filling: Mk III and Mk V - Magnesium shavings and gunpowder, or calcium silicide and gunpowder.

Remarks: The smoke-filled bombs are used for daylight operations; the flash-filled at night.  Because of their solid cast-iron noses, these bombs should not be used against lightly armored targets.

The Bombs Mk I and Mk III are identical, except for the fillings.  The Mk IV, which replaces the Mk I, is similar to it in construction, but differs in the following respects:  The safety plunger and transit safety pin have been increased in diameter.  The plunger is retained by a flexible steel safety wire permanently attached to a safety collar which is threaded internally to accept the transit safety pin.  The transit safety pin is screwed into the safety collar, thus retaining the assembly firmly until the bomb is on the carrier.

The Bomb Mk V, which replaces the Mk III, is mechanically identical to the Mk IV, but differs in the filling.


Infantry Training Bombs Introduction

These bombs, of which there are two sizes, are used to train infantry units under simulated combat conditions.  The bomb casing is splinter-less, thus reducing the possibility of training injuries, but the noise and flash produced are comparable to those of the explosions of a medium-sized bomb. 

The bombs are fuzed with a pistol/detonator combination.  The 6lb bomb takes a Nose Pistol No.34, while the 60lb bomb takes a Nose Pistol No.42.

The bomb bodies are constructed of rolled pressed paper, and are closed by a pressed-paper head.

IT 6lb Mk I (Service)

Overall length: 20 inches
Body length: 20 inches
Body diameter: 3.8 inches
Total weight: 6 pounds (approx.)
Charge/Weight ratio: 33%

Fuzing: Nose Pistol No.34

Color and markings: Dark green overall,
1/2-inch red band 1 inch from nose,
1-inch light green band 4 inches from the nose.

Body Construction: The body consists of a rolled-paper cylinder shellacked internally and externally.  A the nose end an adapter is attached to a chamfered cardboard washer, and threaded internally to receive the pistol.  The main filling is held in the body between a paper cup amidships and two felt washers at the nose, which position the exploder.  The paper cup is supported by a cardboard washer, which is in turn supported by a split collar secured to the body by four rivets.

Tail Construction: No separate tail unit is used.  The empty after portion of the body serves as a tail.
Suspension: The bomb is suspended by a suspension lug on a band approximately six inches from the nose.

Explosive Components:
Exploders: 3 CE pellets, two of which are perforated

Filling: 2lb of CE TNT 30/70, or desensitized Pentolite Grade I

Remarks: This bomb is used to provide realistic bombing attacks on infantry undergoing training.  The bomb is splinterless, but the nose and flash are comparable to those of a medium-sized bomb used for dive bombing operations.

IT 60lb (Service)

Overall length: 36 inches (w/o fuze extension rod)
Body diameter: 10.6 inches
Total weight: 60 pounds (approx.)

Fuzing: Nose Pistol No.42

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

Body Construction: The body and tail unit are in one piece, and are manufactured of rolled and pressed paper.  The rolled-paper charge container, containing pentolite, rests on a felt washer seated on a diaphragm in the body.  The head of the charge container is closed by a rolled-paper head which is pinned, shellacked, and taped in position.  The head is recessed to house the pistol adapter.  A 6-inch extension rod is fitted to the Nose Pistol No.42, by means of a spring washer, after the arming vane cap has been removed.

Suspension: The bomb is suspended by a single suspension lug approximately 10 inches from nose of bomb, which is secured to the bomb body by two bolts.

Explosive Components:
Exploder: 3 CE pellets

Filling: Pentolite

Remarks: This bomb is designed to be used in training operations of ground personnel, simulating realistic bombing attacks.


Miscellaneous Bombs Introduction

This chapter covers two bombs which do not fall within the regular classification system.  One bomb is the "Nickle" Leaflet bomb, which is a US Army M26 flare modified to carry propaganda leaflets.  The other bomb is the Type H, A.D. Apparatus, which is designed to provide aircraft with a defense against fixed gun fighter planes by laying a parachute-supported aerial mine in their path.  It is similar in principle of operation to several of the rocket-propelled A.D. apparatus.

"Nickle" Leaflet Bomb No.2 Mks I and II (Service)

Overall length: 47 inches
Body diameter: 8 inches
Total weight: 64 pounds
Filling: Propaganda leaflets

Fuzing: Nose Fuze No.860 Mk II

Color and markings: Grey overall; white stencilling

Body Construction: This bomb is an adaptation of a US Army Flare M26, whose purpose is to scatter large quantities of propaganda leaflets over enemy occupied territory.

The bomb consists of a light sheet-steel body, closed at the front end by a plastic transit plug, and at the after end by a light sheet-steel lid.  When the bomb is filled and ready for use, this lid is held in place by four soft steel tabs, which are welded at one end to the bomb body and have their free ends bent over the lid.  Four tail fins are secured to the after end of the bomb casing.

Inside the body is a wooden frame consisting of a block, which fits snuggly in the nose of the bomb but does not completely fill it, and three equispaced battens, each of which is secured at one end to the block.  These battens extend the full length of the bomb body between the block and the lids..  The leaflets are contained in the wooden frame between the battens.  The outer end of the block is recessed to locate an ejection charge containing 400 grains of G.12 gunpowder held in a muslin bag.

Since the bomb is an American weapon, it must be somewhat modified for British use.  A special brass adapter is threaded into the nose fuze pocket.  The adapter is internally threaded to receive the larger Fuze No.860 Mk II.  In the base of the adapter is located a charge of G.12 gunpowder, sealed at either end by a waterproof disc.

Suspension: The Bomb Mk I is designed only for aircraft having the American-type bomb stowage.  It is fitted with two American type lugs attached to suspension bands around the bomb body.  The Bomb Mk II is designed for suspension only in a Universal-type bomb carrier.  The bomb is fitted with both British- and American-type suspension lugs, but the American lugs have been moved out of position to fit beneath the standard crutching forks of the Universal-type carrier, and act as strengthening bands for the light-gauge steel body.

Functioning: When the fuzed bomb is released from the plane, it falls freely until the fuze functions, and the gunpowder in the adapter is initiated.  The flash from the gunpowder ignites the ejection charge, and the pressure from the explosion of the ejection charge forces the wooden frame containing the leaflets out of the after end of the bomb body.  The lid is thrown clear and the contents ejected from the tail.  After the ejection, the wooden frame falls end-over-end, and the leaflets fall out of the frame and scatter over the target.

Type H, A.D. Apparatus Mk II (Service)


Description: The apparatus consists of a housing canister, support parachute, bomb, steel cable, and towing parachute.

The cylindrical housing canister is a metal tube, the open end of which is closed by a lid.  A hinged metal flap is attached to the lid to insure its release when the apparatus is dropped.  A lid-retaining assembly holds the lid and its flap in place until the bomb is dropped.

The support parachute's shroud lines are tied to an attachment ring which is connected to the double snatch link of the bomb fuze by circlips.

The discus-shaped bomb has a central fuze hole, and a rolled edge to facilitate penetration.  The fuze is secured in place by a nut.  The bomb is filled with CE/TNT.

The fuze incorporates an all-ways acting striker mechanism, a double snatch link, and a CE filled magazine, which is screwed into the base of the fuze and closed by a plug.  This plug has an eye to which the cable is attached.  The fuze body houses a striker, creep spring, and shutter.  When the detonator in the shutter is held out of line with the striker by the striker point engaging a hole in the shutter, the fuze is unarmed.  If the striker point is withdrawn from  this hole, the shutter is moved into place by its spring and held in alignment by a spring-loaded locking pawl.  The striker is retained in the shutter hole against the pressure of its creep spring by a safety plunger, which is retained in position in the actuating rod by a headed rod.  A shear wire and the upper balls of the snatch link connect the headed rod and the actuating rod.  The flanged head of the actuating rod is housed in the fuze body.

The double snatch link consists of a body housing the actuating rod, which carries an upper and lower set of balls, a washer, sleeve, and compressed spring.  The upper balls bear on the washer, which presses against the upper end of the spring, and the lower set of balls bear against the under side of the flanged end of the sleeve.  The parachute attachment ring is joined to the snatch link body by two circlips. 

The support parachute, which is packed and held together with rubber bands so it will open only on sharp impact, is attached to the fuze eye by a one hundred foot cable.

Functioning: When the apparatus is released from the plane, the lid is blown off and, acting as a pilot chute, withdraws the support parachute, followed by the bomb, cable, and towing parachute.  The canister falls away and the cable assumes a vertical position.

The opening of the support parachute imparts a jerk to the double snatch link, which then releases the lower set of balls.  When the cable is completely unwound, the upper set of balls is ejected and the juncture of the fuze to the support parachute is transferred to the shear wire.

When the pursuing enemy plane collides with the cable, another jerk is transmitted to the bomb and support parachute.  The ends of the shear wire are cut by the snatch link washer, which then engages the headed rod, and again cuts the shear wire to release the safety rod and arm the fuze.  The support parachute and snatch link are then freed from the assemblage.  The shock of impact also opens the towing parachute, which prevents the cable from slipping over and away from the plane.  The bomb is whipped against the plane, and its hard edges penetrate the skin.  Penetration causes deflection of the actuating rod, which forces the striker into the detonator and explodes the bomb.

Next Time: Obsolete Bombs

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