Monday, 16 April 2018

American Projectiles and Explosives - Ground Pyrotechnics (Part 3)

American Projectiles and Explosives

Ground Pyrotechnics


Parachute Trip Flare M48

Diameter of flare tube: 2.5 inches
Height of trajectory: 300-500 feet
Burning time: 20 seconds
Intensity: 100,000 candlepower
Effective Illumination: Circle of 800 yards radius

Color: White to Yellowish

Use: The flare is used to give warning of enemy marauders or infiltrating hostile troops; also, for illumination or signaling.

Description: The flare consists of a 1/4-inch pipe and a steel tube approximately 2.5 inches in inside diameter, which are attached to a base plate that contains a 75-grain propelling charge.  The steel tube contains a delay fuse, an expelling charge, a candle, and a parachute assembly.  The 0.25-inch pipe and the firing mechanism are joined by a coupling, and the pipe is threaded to the base plate.  The firing train is composed of a primer, an igniter, and a relay charge.  The firing mechanism contains the pressure cap, pull ring and pin, safety screw, safety cotter pin, and spring-loaded firing pin.

Operation: A 20- to 30-pound pressure on the pressure cap or a tension of four to six pounds on the pull pin releases the firing pin and fires the primer.  The primer initiates the igniter, which, in turn, starts the relay charge.  The relay charge sets off the propelling charge, which projects the illuminating shell through the large steel tube to a height of 300 to 500 feet.  The propelling charge ignites a three-second delay fuse in the shell.  The delay fuze ignites an expelling charge which expels a parachute-supported candle from the shell.

Trip Flare M49

Length: 3.8 inches
Diameter: 2.5 inches
Burning time: 1 minute
Intensity: 40,000 candlepower

Color: White to Yellowish

Use: The Trip Flare M49 has the same uses as the Parachute Trip Flare M48

Description: The flare has a grenade-shaped cylindrical body, with a nose fuze that protrudes 0.875-inch from the head end.  A mounting bracket and a spring-loaded trigger mechanism are mounted on a metal base cap.  The upper arm of the trigger is attached to a trip wire, and the lower arm of the trigger restrains the safety lever after the removal of the safety pin.

Operation: A pull on the trip wire rotates the upper trigger arm away from the fuze lever.  If the trip wire is cut, the upper trigger arm, which is restraining the fuze lever, rotates away from the fuze lever but in an opposite direction from above.  A grenade-type fuze is used, but is has no delay element.  The fuze ignites the flare simultaneously.

Trip Wire Flare Mk 1 Mod 0

Length of tube: 5.5 inches
Diameter of tube: 2.5 inches
Weight: 3.5 pounds
Burning time: 65 seconds
Candlepower: 100,000
Effective illumination: Area 500 feet in diameter

Use: The purpose of the flare is to reveal the approach of enemy troops.

Description: The flare case is a steel tube approximately 5.5 inches long and 2.5 inches in diameter.  Fixed to one end is a pull-type, spring-actuated firing mechanism to which the trip wire is attached.  Enclosed in the tube are the primer, black-powder charge, impregnated muslin disc, and pyrotechnic composition.  Two 40-foot lengths of wire are available, making it possible to have two trip wires running in opposite directions.  A web belt secures the flare to a tree.

Operation: A tug of three pounds or more on the trip wire draws the plunger and firing pin away from the primer and compresses a spring which surrounds the firing pin.  As the plunger is pulled away from the firing mechanism, its notched end disengages from that of the firing pin, which is then forced against the primer by the compressed firing-pin spring.  The primer ignites 0.3 grams of black powder.  The black powder ignites the impregnated muslin disc, and in turn the pyrotechnic composition.  The resultant gas pressure blows out the closure disc from the head, and the flame from the burning candle illuminates the surrounding area.  White smoke given off by the flare does no interfere with the effectiveness of the illumination.

Remarks: To prevent self illumination, the flare should be mounted about 125 yards before friendly positions.  While mounting the flare, personnel should wear steel helmets, and heads should be kept below and away from the top of the flare.

Ground Flare M81-M83

No picture available

Length (w/o spike): 7.75 inches
Diameter: 1.75 inches
Weight: 0.88 pounds
Burning time: 2 minutes

Color and Intensity:
-M81: Red - 20,000 candlepower
-M82: Yellow - 25,000 candlepower
-M83: Green - 35,000 candlepower

Use: The flare indicates, to cooperating air elements, a line of position or direction.  It is also used for troop-recognition purposes.

Description: The flare consists of a paper cylinder containing a pyrotechnic composition.  It has a wooden base block with a 20-penny spike through it, and a match head covered by a removable metal cap, under which lies a wooden disc.  A plastic film seals the metal cup to the flare body.  The outer head of the wooden disc has the scratching surface required to ignite the match composition.

Operation: The flare is stuck in the ground with the spike as a support.  The plastic seal is pulled off and the wooden disc scratched against the match composition, which ignites the flare.

Remarks: These ground flares are not procured by the Navy at present.

Target Rocket Flare Mk 1 Mod 0

Weight: 3 pounds

Use: The Target Rocket Flare Mk 1 Mod 0 is used with the 3.25-inch Rocket Targets Mk 10 and Mk 11.

Description: A pyrotechnic candle, secured into a wooden body, is housed in a steel tube.  An electric squib is located over the starter composition of the candle.  A steel cup shields the ignition end of the flare, and squib leads are coiled inside the nose cap.

Operation: Tear off the adhesive strip and remove the cover.  Place the flare over the nose of the rocket, and uncoil the squib leads.  Fasten the alligator clips to the cotter pins of the leads, and fire.

Airport Flare M13 (Obsolete)

No picture available

  Length: 23.1 inches
Diameter: 1.75 inches
Intensity: 40,000 candlepower
Burning time: 3 minutes

Use: Airport Flare M13 is used to provide illumination for airplane landing at emergency fields, and to illuminate targets and objectives.  A further use is to prevent infiltration or surprise by enemy troops.

Description: The flare consists of a cylinder; the top cover sealed with a strip of adhesive tape, and a seven-inch hollow chip-board tube mounted to one end of the cylinder.

Operation: Remove the adhesive tape and slip the hollow tube over a rod stuck in the ground.  Pull on the lanyard attached to the ignition wire to fire the flare.

Remarks: This flare is not procured by the Navy.

Airport Flare M76

No picture available

  Length: 32 inches
Diameter: 6 inches
Intensity: 800,000 candlepower
Burning time: 6.5 minutes

Use: Airport Flare M76 is used to indicate the end of a runway in a fog.

Description: This flare consists of a cylinder containing a candle similar to, but larger than, the candle of the Flare AN-M26.  The cylinder is fitted with a socket base arrangement into which four channel-shaped legs may be inserted to hold the flare upright on the runway.

Operation: The flare may be initiated by the use of the electric squib or by pull on the release fork which allows the spring-loaded firing pin to strike the primer.  The primer acts directly to ignite the first fire composition.

Remarks: Airport Flare M76 is not procured by the Navy.

High-Altitude Parachute Mortar-Fired Flare Mk 20 Mod 0

No picture available

  Length: 10.75 inches
Diameter: 2.5 inches
Weight: 5 pounds
Height of trajectory: 1,000 feet
Intensity: 85,000 candlepower
Color: White
Burning time: 60 seconds
Rate of fall after ignition: 16 feet/second

Use: This high-altitude flare is used to illuminate seaplane landing areas at night, and to illuminate an island base when low ceilings do not permit proper visibility from normal flying levels. 

Flare: The flare consists of a cylindrical steel tube body with a copper cup welded to the closed tube body with a copper cup welded to the closed end of the tube.   The body contains an expelling charge, a pyrotechnic candle, and a silk parachute.  The copper cup contains a fuse assembly, a propelling charge, 25 grams of a combination smokeless powder and black powder, and a standard shotgun primer.

Mortar: The mortar consists of a steel tube 36 inches long and 2.8 inches in diameter.  The tube is screwed into a steel base plate 0.75 inches thick and 12 inches square.  The base plate is provided with a central stud into which is pressed a hardened steel firing pin.

Operation: Remove the closing cap from the end of the mortar.  Attach a 30-foot lanyard to the brass release pin and insert the pin in the two holes drilled transversely about six inches from the end of the mortar.  Insert the flare into the mortar so that it rests on the release pin, with the copper end down.  Fire the flare by pulling the lanyard, thus removing the release pin.  The flare falls to the bottom of the mortar, firing the primer.  The primer sets off the propelling charge and ignites the delay fuse.  the expanding gases force the copper cup away from the flare and fill the bore of the mortar.  The flare is propelled 1,000 feet into the air, at which time the delay fuse ignites the expelling charge.  The pyrotechnic candle and parachute are expelled, the expelling charge igniting the candle.

Remarks: A suitable barrier should be erected to shield personnel firing the flare.  In case of a misfire, wait at least three minutes before disassembling the mortar.  Clean mortar tube after firing.

Next Time: Shipboard Pyrotechnics

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