Monday, 3 April 2017

British Explosive Ordnance - Smoke, Illuminating, and Incendiary Grenades

British Explosive Ordnance

Smoke, Illuminating, and Incendiary Grenades

Smoke Hand Grenade, W.P., No.77 Mks I and II (Service)

Overall length: 4.65 inches
Diameter: 2.3 inches
Total weight: 13.5 ounces
Filling: White Phosphorus
Filling weight: 8 ounces
Fuzing: No.247 Mk I, II, or III
Delay: None

Color: Green
Markings: Mk II has red and white bands around center

Description: The tin-plate body is cylindrical in shape except near the base, which is in the form of a truncated cone.  The coned portion has a flat base in which the filling hole is formed.  The hole is closed by a soldered lid.  The tin-plate closing arrangement at the head of the body includes a threaded socket with a central pocket for the detonator.  The socket receives the housing for the attachment of the fuze.  The tin-plate housing serves as an adapter for the attachment of the fuze to the body, and is in the form of a cap with a knurled periphery and a socket.  The socket has a central hole and is threaded to engage with the socket in the body.

Operation: The housing, together with the fuze, is removed by unscrewing the housing; and the detonator is inserted in the pocket with the open end towards the fuze.

The adhesive tap is then removed and the safety cap unscrewed in one-half turn.  After the cap is removed, the tape must be held in place by the forefinger and thumb.  When thrown, the weight on the end of the tap causes the tape to unwind and pull out the safety pin.  Only the creep spring is now holding the striker away from the primer cap.  On impact, the striker is forced into the primer cap, which initiates the detonator and explodes the grenade, scattering the white phosphorus.  The white phosphorus ignites spontaneously on contact with air, causing a heavy white smoke screen.  The small fragments of phosphorus are of an incendiary nature.

Remarks: The Mk II model was introduced to enable this grenade to be used for training without incurring the risk of fire which attends the use of the Mk I.  The Mk II model has a cylindrical body and is filled with titanium tetrachloride.  The Grenade Mk II is used only in training and is not issued for use under service conditions.  The Grenade Mk I/I has a seamless body.

Smoke Hand Grenade No.79 Mk I (Obsolete) and Mk II (Service)

Overall length: 7 and 2/3 inches
Diameter: 4 inches

Total weight: Depending on filling
-1 pound, 10 ounces
-1 pound, 12 ounces
-1 pound, 6 ounces

Filling and weight:
-PN 83 (M): 14.5 ounces
-PN 398 or 436: 1 pound, 3 ounces
-PN 317 or 411: 1 pound, 5 ounces

Fuze: No.247 Mk I, II, or III
Delay: None

Color: Light green
Markings: Standard

Description: This grenade has a cylindrical tin-plate body  The lid is soldered in one or two places tot he body, and further secured by adhesive tape.  The body is closed by a disc, which is pressed in and fitted with a container for the igniter, while the lid carries a threaded socket for the fuze holder.

The grenade is filled with a smoke mixture, and the igniter container, with PN 227 composition.  A gunpowder-primed cambric disc is fitted above the container to pick up the flash from the fuze and ignite the PN 227.

Operation: The adhesive tape and the fuze cap are removed.  When the grenade is thrown, the tape unwinds and withdraws the safety pin.  Only the creep spring is then holding the striker away from the primer cap.  On impact, the striker is forced against the cap.  Smoke emission commences about five seconds later and continues for about 1.5 minutes.

Remarks: The Grenade Mk II is similar in construction to the Mk I, but employs a Bouchon type igniter designated Striker Mechanism No.5.

Smoke Hand Grenade, W.P., No.80 Mk I (Service)

Overall length: 5.5 inches
Diameter: 2.4 inches
Total weight: 19.5 ounces
Filling: White phosphorus
Filling weight: 13 ounces
Fuze: Striker Mechanism No.2
Delay: 2.5 to 4 sceonds

Color: Green
Markings: Standard

Description: The empty components of this smoke grenade comprise a cylindrical body, top, detonator tube, bottom with filling hole, and a filling-hole plug.  All are of tin plate except the detonator tube, which is of brass.  The top is secured to one end of the body by a folded joint, which is soldered.  A threaded recess in the top accommodates the striker-mechanism adapter and also carries the detonator tube, which is secured to it by soldering.  A charge of white phosphorus is contained in the body and retained by a bottom plate folded over onto the body and soldered.  A filling hole in the bottom is closed by a soldered plug.  The Detonator No.75 Mk II is of sufficient strength to burst the grenade and scatter the W.P.

The striker mechanism comprises a zinc-base alloy (Mazak) housing which carries the striker, striker axis pin, and striker spring.  It is suitably shaped to accommodate the safety lever, which is retained by a safety pin passed through corresponding holes in the lever and housing.  The pin is provided with a ring to facilitate withdrawal.  This mechanism is very similar to the Bouchon type igniter commonly used in United States grenades.

Operation: The safety pin is removed, care being taken to hold the safety lever firmly in position.  The grenade is then thrown.  During flight the striker spring causes the striker to rotate about its axis, throwing off the safety lever, and striker the percussion cap.  The grenade bursts in 2.5 to 4 seconds and scatters the white phosphorus, which ignites on contact with air and emits a dense cloud of white smoke.

Smoke Hand Grenade, W.P., No.81 Mk I (Service)

Overall length: 5.25 inches
Diameter: 2.4 inches
Total weight: 1.5 pounds
Filling: W.P. and H.C. Smoke Mixture
Fuze: Striker Mechanism No.3 Mk I
Delay: 2.5 to 4 sceonds

Color: Green
Markings: Standard

Description: The grenade is composed of two parts; a bursting white phosphorus component and a generator component.  Both components are made of tin plate, and construction follows normal trade practice.  They are cemented together immediately after filling.  The W.P. component is similar in construction to Grenade No.80, but is shorter and contains about half a pound of W.P.  It is initiated by means of Striker Mechanism No.3 Mk I, which fires a Detonator No.75 Mk II.  The striker mechanism is screwed into a recess in the top of the W.P. component above a brass detonator tube.  The adapter of the striker is cemented into position.  The housing can be unscrewed for priming.  This housing carries the spring-loaded striker held back by the safety lever and safety pin.  The adapter and housing castings are made of zinc-based alloy.

The Detonator No.75 Mk II consists of a cap mounted in a die-cast cap chamber (similar to Detonator No.35M) with a length of Safety Fuze No.17 Mk I Bickford to which is crimped a Detonator No.78.  The generator component is filled with H.C. Smoke Mixture and is ignited by a primed cambric disc, which is ignited by the flash of the detonator.  This component is screwed and cemented to the bottom of the W.P. component.

Operation: The grenade is primed by removal of the housing assembly, insertion of the detonator, and reassembly of the striker mechanism.  To function, the lever is held firmly against the grenade body and the safety pin removed.  As soon as the grenade is thrown, the fly-off lever leaves the body of the grenade and the cap is struck.  The detonator fires after a delay of 2.5 to 4 seconds, producing an immediate burst of white phosphorus.  The smoke and incendiary effects are comparable with Grenade No.77 Mk I, and the safety distance is a little greater.  The generator component is ignited when the detonator bursts and attains full emission before the phosphorus smoke is dissipated.  Rapid smoke emission from the generator then follows for about 45 seconds.

Colored Smoke Hand Grenade No.83 Mks I-II (Service)

Overall length: 4.45 inches
Diameter: 2.55 inches
Total weight: 16 ounces (approx.)

-Red Smoke: PN 469A
-Yellow Smoke: PN 473A
-Green Smoke: PN 468A
-Blue Smoke: PN 471A

Filling weight: 6 ounces

-Mk I: Match Composition Igniter
-Mk II: Striker MEchanism No.3 Mk I or No.4

Delay: 4 seconds

Color: Green
Markings: Standard

Description: This smoke grenade is cylindrical in shape and contains a perforated canister filled with blue, green, red, or yellow smoke composition.  The igniting arrangements are carried in the head.  The grenade body is of tin plate, while all other empty components are of black plate.

The No.83 Mk I has a flanged top secured to one end of the body by a folded joint.  The top is recessed to accommodate the match head.  Four equi-spaced smoke-emission holes are prepared around the top and sealed by shellacked adhesive tape.  Match composition PN 196 is filled into the hole of a cylindrical cork match head, the composition being built up on on the outside to give a good striking medium.  A striker, in the form of a strawboard washer primed with striker composition PN 288 on one-half of one side, is carried int he top of the body, primed side uppermost.

The canister body, with its perforations covered by a wrapping of paper coated with glue or other adhesive, is fitted at one end with a flanged top folded over onto the body.  The top is shaped to seat the recessed top of the grenade body containing the match head, and has a one-inch square, or disc, of primed cambric or muslin, shellacked to its underside with the primed surface adjacent to about three drams of composition stemmed into the neck of that canister.  The canister is closed by a cap and retained int he grenade body by a bottom plate.

A lid fits over the body for transit purposes.  The junction of the lid and body is sealed with a strip of adhesive tape formed with a tab to facilitate removal.  To prevent accidental functioning of the match composition, a pad of tissue paper is interposed between lid and igniter.

The Grenade No.83 Mk II differs from the Grenade Mk I in being fitted with a Striker Mechanism No.3 Mk I or No.4, instead of a match head.  Into the recess in the top of the grenade body is screwed a Mazak alloy adapter for the striker mechanism.  Fitting of the striker mechanism precludes the fitting of a lid to the grenade as in the Mk I.

Operation:First remove the lid and striker of the Grenade Mk I.  The striker must then be drawn sharply across the match composition.  Smoke is emitted about four seconds after ignition and continues for about 20-40 seconds.

In the Mk II, no priming is necessary, as the grenades are issued assembled with igniters complete and ready for use.  The safety pin is removed and the fly-off lever held firmly in position until the grenade is thrown.  During flight, the striker is rotated around the axis-pin by its spring and the fly-off lever is thrown clear.  The striker fires the cap, and a delay of about four seconds ensures before smoke emission commences.  Effective emission continues for about 25 to 45 seconds.

Remarks: The Grenade No.83 Mk I was never produced.  The Striker Mechanism No.4 differs from the No.3 in that it has a plastic body.

Smoke Rifle Grenade, W.P., No.87 Mk I/L (Service)

Overall length: 9.5 inches
Diameter: 3.25 inches
Total weight: 4 pounds
Filling: Polar ammon gelatine dynamite
Filling weight: 3.25 pounds
Fuzing: No.247 Mk I, II, or IIII
Delay: None

Color: Buff
Markings: Red filling ring around the upper body and standard markings.

Description: The Grenade No.87 is a smoke rifle grenade.  The complete grenade consists of a white phosphorus filled head, an adapter, fuze, and tail unit.  The head is similar in construction to the Smoke Grenade No.77 Mk I, differing only slightly in size and markings.  An adapter, which threads into the after section of the grenade head, is itself internally threaded to take the tail unit.  The tail unit and fuze of this grenade are similar to those used in the Rifle Grenade No.85.

Operation: Same as for the Grenade No.85 except that explosion of the booster bursts the grenade case, spreading the white phosphorus, which ignites when exposed to air.

2.5-inc Signal and Illuminating Rifle Grenade Nos.57, 58, 59, 60, 61, and 62 (Obsolescent)
Grenade No.57
Type of grenade: Illuminating
Number of stars: 1
Burning time: 5.5 seconds
Total weight: 1 pound, 0.5 ounces
Overall length: 2 and 3/4 inches
Color: Buff
Markings: Red star in white circle.

Grenade No.58
Type of grenade: Illuminating with parachute
Number of stars: 1
Burning time: 28 seconds
Total weight: 1 pound, 7 ounces
Overall length: 5 inches
Color: Buff
Markings: Red star in white circle.

Grenade No.59
Type of grenade: Day signal
Number of stars: 12 red, or 12 green, or combination
Burning time: 7 seconds (approx.)
Total weight: 1.5 pounds
Overall length: 3 and 1/2 inches
Color: Buff
Markings: Colored or partli-colored triangle to indicate star colors; "M" stencilled on triangle.

Grenade No.60
Type of grenade: Night signal
Number of stars: 12 red, or 12 green, or combination
Burning time: 11.5 seconds (red); 8 seconds (green)
Total weight: 1.5 pounds
Overall length: 3 and 1/2 inches
Color: Buff
Markings: Colored or partli-colored triangle to indicate star colors; "M" stencilled on triangle.

Grenade No.61
Type of grenade: Day signal with parachute
Number of stars: 3 red, or 3 green, or combination
Burning time: 25 seconds (red); 20 seconds (green)
Total weight: 1 pound, 4.5 ounces
Overall length: 5 and 1/2 inches
Color: Buff
Markings: Three colored triangles to indicate star color

Grenade No.62
Type of grenade: Night signal with parachute
Number of stars: 3 red, or 3 green, or combination
Burning time: 12 seconds (red); 19 seconds (green)
Total weight: 1 pound, 4.5 ounces
Overall length: 5 and 1/2 inches
Color: Buff
Markings: Three colored discs to indicate star color

Description: The construction of this entire series of grenades is generally similar to that of the 2.5-inch Illuminating Rifle Grenade No.57 Mk I, whose description follows.

The body of the grenade consists of a cylindrical steel case, whose base is closed by a steel base plate.  The top of the body is closed by several millboard discs.  A friction-fit steel lid, with a ring for easy removal, fits over the base to protect the ignition system.

The base plate fo the grenade has a drilled radial hole, which contains the ignition system.  A small hole connected to its outer end allows the flash of the cartridge to contact the ignition system, while a coned hole at its inner end leads to the gunpowder burster in the interior of the grenade.  The ignition system, which is retained in the radial hole by a screwed plug, consists of a tube of primed cotton cambric, a layer of gunpowder, a delay pellet, and another small charge of gunpowder, which relays the flash to the gunpowder burster of the grenade.  The paper-wrapped star rests on a millboard disc, which separates it from the gunpowder burster.  The star composition is ignited by a layer of priming composition, in turn ignited by a small charge of sulphurless gunpowder; all of which are integral components of the star.

Operation: The base lid is removed and the grenade inserted into the discharge cup base-first.  On firing, the propellant gases initiate the ignition system of the grenade and propel it into the air.  The delay allows the grenade to reach a height of approximately 250 feet before the burster ejects and ignites the star.

Remarks: These grenades are used in the 2.5-inch discharger cup and fired by means of the 0.303-inch H. Rifle-Grenade Cartridge Mk IZ.  The 2-inch mortar signal and illuminating bombs have largely replace this series.

Incendiary Hand or Rifle Grenade No.76 Mk I (Obsolete)

Total weight: 19 ounces

Filling: 128 cc phosphorus mixture (75% phosphorus and 25% sulphide of phosphorus), 21 cc of water, 110 cc benzine, and a stick of crude rubber 3.5 inches long and 1/4-inch in diameter.

Markings: Red caps indicate suitability for hand throwing only; green caps indicate suitable for hand throwing or projecting.

Description: This grenade consists of a short-necked, 1/2 pint glass bottle containing an incendiary filling, and closed by a crown cap.  Ten percent free space is left above the filling for expansion.  During storage, the strip of crude rubber dissolves and increases the viscosity of the liquid.

Operation: The grenade must be thrown or projected with enough force to break on impact.  When broken, the phosphorus mixture ignites on contact with the air, thus setting the benzine alight.  The grenade is designed to be thrown against armored-force vehicles to produce an incendiary and smoke effect.

Remarks: The grenade should not be shaken before throwing, as agitation causes the formation of an emulsion in which the droplets of phosphorus are protected from the air by a covering of water.

1 and 1/4-pound Incendiary Bomb Mk I (Obsolescent)

Weight: 1 and 1/4 pounds
Filling: Incendiary mixture
Delay: 5 seconds
Color: Red

Description: The empty bomb consists of a cylindrical tin-plate body which has an externally threaded neck, bakelite adapter and safety cover, zinc-alloy cap chamber, tin-plate cup securing cap chamber, and rubber washer.  The body is filled with an incendiary composition and an ignition system which comprises an igniter unit and fuze assembly.

The fuze assembly consists of a rim fire cap secured to a length of safety fuze, which should give a delay of approximately five seconds.  The cap chamber is passed over the safety fuze on to the sleeve of the rim fire cap.  A length of copper tube is positioned over the fuze and secured by crimping.  The igniter unit consists of composition housed in a tin cup.  On top of the igniter composition is a primed cambric disc and a paper sleeve.

To assemble the whole ignition system, the fuze assembly is inserted through the bakelite adapter and the free end of the fuze tube is secured to the paper sleeve in the igniter unit.  The cap chamber of the ignition system is secured in position by screwing the cup securing cap chamber onto the adapter.  The adapter with complete ignition system is screwed on to the neck of the bomb body, the igniter unit positioning itself in the paper cup in the body.  The safety cover is screwed down to the rubber washer, housed in the adapter recess, thus forming a seal.  A patch of adhesive tape is affixed to the adapter and safety cover.  This prevents removal of the safety cover during transit.

Operation: Remove the adhesive tape and safety cover.  Place the bomb on its base in the required position.  Strike the cap with a hard surface.  The bomb is not to be touched after striking the cap.

Next Time: Anti-Tank and Anti-Personnel Mines

No comments:

Post a Comment