Monday, 12 March 2018

American Projectiles and Explosives - Depth Charges and Slick Markers

American Projectiles and Explosives

Aircraft Pyrotechnics

Day Depth Charge Marker Mk 1 Mods 1 and 2

Length: 11.88 inches
Diameter: 3.46 inches
Weight: 3.5 pounds
Weight of dye: 2.75 pounds
Weight of bursting charge: 30 grams
Effective releasing altitude: Up to 1,000 feet
Visibility: 3,000 yards from deck of ship; 5 miles from aircraft

Use: The marker is used to indicate the initial point of contact with submarines and provide a reference point for further search and attack during day operation.

Description: The marker consists of a circular wooden block on which is mounted a grenade-firing mechanism with a 15-second delay.  Fluorescein dye is contained in two cylindrical paper cans, one attached to each flat side of the wooden block; and a celluloid tube containing the black-powder bursting charge is attached to the delay element and extends through the wooden block into the paper cans.  The dye is rusty red in color when dry, but a water solution of the dye is yellow-green.

Operation: The operator clasps the marker firmly in one hand, being sure that the release lever is held against the body of the marker.  With the other hand, he pulls the safety ring which is attached to the safety cotter pin and launches the marker by throwing it over the side.  When the marker is released, the spring-loaded striker forces the release lever off.  The striker, rotating about a hinge pin, hits the primer that ignites the 15-second delay fuze.  The delay gives the marker sufficient time to reach the water and float on the surface, and then ignites the bursting charge.  The gases evolved from the charge burst the dye containers and spread the dye on the water, forming a yellow-green slick about 40 feet in diameter.  The slick lasts for 45 to 60 minutes.

Night Depth Charge Marker Mk 2

Length: 7 inches
Diameter: 5 inches
Weight: 2.5 pounds
Effective releasing altitude: Up to 3,000 feet
Visibility: 4 miles from deck of ship; 10 miles from aircraft

Burning time: 55 minutes
Ignition time (after impact): 70-90 seconds

Use: The marker is employed to indicate the initial point of contact with submarines and provide a reference point for further search and attack during night operations.

Description: The marker is a sealed, cylindrical, metal container that has a centrally located tube, sealed on both ends by tear strips with a pull ring attached, and containing calcium phosphide.  The main charge is calcium carbide that surrounds the central tube and is held in one end by a screen.  This produces a concentration of weight at one end and allows the marker to float in an upright position.

Operation: After the two tear strips are pulled off, the marker is launched by throwing it overboard.  Water enters through the small calcium carbide (producing an inflammable gas, acetylene) and with the calcium phosphide (producing a spontaneously ignited gas, phosphine).  Both gases escape from the small holes in the top and ignite within 70 to 90 seconds after impact with the water.  In extremely cold weather, the ignition delay may be somewhat longer.  The resulting flame is about nine inches high.  If it should be put out by rough water, the gases will ignite again.

Slick Marker Cartridge AN-Mk 1

No picture availabe

Length: 3.8 inches
Diameter: 1.5 inches
Muzzle velocity: 300 feet/sec
Weight of dye: 28 grams

Use: This marker is used primarily to provide reference points for aircraft engaged in anti-submarine warfare.

Description: The cartridge is composed of a shotgun-type case containing a primer, a black-powder propelling charge, and the projectile.  The projectile has a thin aluminum case and contains 28 grams of fluorescein dye and a black-powder bursting charge initiated by a Bickford-type fuze.

Launching: The marker cartridge is fired in the Pyrotechnic Pistol AN-M8, which may be held in the hand or mounted in the Mount M1.

Operation: When the cartridge is fired, the black powder in the head of the case propels the projectile from the pistol and at the same time ignites the Bickford fuze.  The fuze burns for about eleven seconds before igniting the bursting charge which expels the fluorescein dye out into the water.  The projectile has a positive buoyancy and will remain near or at the surface until a small, bright green slick is created.

Remarks: This cartridge should not be fired from altitudes greater than 500 feet, because the cartridge must be in the water when it bursts.

Slick Marker AN-M59

No picture available

Length: 10.875 inches
Diameter: 3.375 inches
Weight: 2.9 pounds

Use: This is the standard all-purpose sea marker for daylight use: to provide reference points; to aid in determining drift; and to provide practice bombing targets on water.

Description: This marker consists of a paper composition case filled with a  fluorescein dye.  It is protected by a cylinder of papier-maché, which does not interfere with its function.

Launching: The marker is dropped by hand from a plane.

Operation: Upon impact with water, the case shatters and the dye spreads upon the surface.

Army Flares

M8 and M8A1

No picture available
Length: 25.5 inches
Diameter: 4.25 inches
Weight: 18 pounds
Color: Yellow
Intensity: 850,000 candlepower
Burning time: 3 minutes
Rate of fall after ignition: 500 feet/min

Use: The flares are used in emergency night landings.

Description: Each flare consists of a cylinder containing an unshaded candle.

Operation: Army Flares M8 and M8A1 are similar in operation to the Flares An-M26, except that the hang wire pulls the parachute directly from the case.

Remarks: The M8 is similar to the M8A1, except that the latter flare burns with a white light approximately 250,000 candlepower.

M9 and M9A1

Picture seen above

Length: 13.8 inches
Diameter: 2 inches
Weight: 1.9 pounds
Color: Yellow
Intensity: 60,000 candlepower
Burning time: 1 minute
Rate of fall after ignition: 400 feet/min

Length: 15.05 inches
Weight: 2.1 pounds

Use: This flare was designed to satisfy the requirements for a small parachute flare for reconnaissance.

Description: The flare consists of a cylinder containing a candle, designed to be projected with the Pyrotechnic Pistol AN-M8.

Operation: The flare is discharged from the pistol and the delay fuse is ignited.  The fuse burns for 2.5 seconds and ignites the expelling charge, which expels the candle and parachute, simultaneously igniting the candle.

Remarks: This flare is not procured by the Navy.

M24 (Obsolete)

Picture seen above

Length: 37 inches
Diameter: 8 inches
Weight: 47 pounds
Color: Yellow
Intensity: 800,000 candlepower
Burning time: 3 minutes
Releasing altitude: 2,500 to 3,000 feet
Speed of release: Not over 200 mph
Rate of fall after ignition: 700 feet/min

Use: The flare is a substitute standard for night observation and bombardment.

Description: It consists of a simple cylinder without hemispherical nose or tail fins; otherwise, it is similar throughout to the AN-M26, without the nose time fuze.

Operation: The flare is similar to the AN-M26 except that the hang wire acts directly to pull the parachute from the flare case.

Remarks: This flare was not procured by the Navy.

M6 and AN-M26

Picture seen above

Length: 50 inches
Diameter: 8 inches
Weight: 53 pounds
Color: White light
Intensity: 800,000 candlepower
Burning time: 3 to 3.5 minutes
Releasing altitude: 4,000 to 25,000 feet
Rate of fall after ignition: 700 feet/min

Use: These flares are used to provide illumination for night bombardment; also may be used to blind anti-aircraft defenses.

Description: The flare is enclosed in a metal cylindrical case with a rounded nose and tail fins.  In the nose is a mechanical time fuze.  The tail end is closed with a shipping cover that has a handle attached and sealed by a strip of tape.  The case is equipped with two suspension lugs 14 inches apart.

Operation: When the flare is dropped, the arming wire is pulled, allowing the vanes of the nose fuze to rotate.  The hang wire is retained and pulls off the cover of the stabilizing-sleeve compartment.  As the flare continues to drop, the tear wire and tear-wire cord pull out the stabilizing sleeve, and the cover-lock cord attached to the shrouds of the stabilizing sleeve unlocks and pulls out the cover lock.  When the sleeve is fully extended, the tear wire breaks, allowing the flare to fall free, stabilized in flight by its fins and stabilizing sleeve.

When the nose fuze functions, the gases of the black-powder booster force the releasing-cup cover out of the detachable cover, releasing the retaining pins from the groove in the flare case and freeing the detachable cover.  As the detachable cover is pulled out by the stabilizing sleeve, a pull-out cord pulls out the parachute.  when the parachute opens, the flare stops with a  jerk, breaking the pull-out cord (which allows the stabilizing sleeve assembly to fall free) and pulling the entire flare assembly out of the flare case (which then falls away).  The sudden stop also pulls the friction wires through the igniters, starting the six-second delay through the center of the candle, which allows full opening of the parachute.

The shock caused by the opening of the parachute is taken by the shock absorbers, made of copper tubing in a spiral or coiled shape.  they straighten out in absorbing the shock.  After the parachute is opened, the delay ignites the first fire, which ignites the candle.  When the first fire is ignited, the gases formed by burning force the rib retainer down, and the spring-loaded ribs jump out, opening the glass-cloth shade.

Remarks: The Flare AN-M26 can be dropped at air speeds up to 240 knots, but above that the stabilizing sleeve is apt to tear away.  The Flare M26 cannot be dropped at air speeds greater than 130 knots, for the same reason.

Next Time: A.A. Flares and Target Identification Bombs

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