American Projectiles and Explosives - Drift Signals and Navy Flares (Part 1)

American Projectiles and Explosives

Aircraft Pyrotechnics







Day Drift Signal Mk 1

Length: 10 inches
Maximum diameter: 3.5 inches

Thickness of case: 0.07 inches
Color of slick: Chrome yellow


Use:  This signal may be used for a reference point for air navigation.


Description:  The case is composed of a water-proofed paper pulp shell pressed in the form of a tear drop, with four fins formed on the tail cone with a diameter approximately the same as the greatest diameter of the nose section.  The only other element of this signal is the very fine metallic powder filling which nearly fills the cavity.


Operation:  When the signal is dropped into the water, the shell breaks, allowing the powder filling to spread out on the surface and form a slick visible to 15,000 feet.


Remarks:  The Day Drift Signal Mk 1 is a Bureau of Aeronautics item.  This marker has replaced the Drift Signal M25, which is now obsolete.









Night Drift Signals AN-Mk 4 and AN-Mk 5 Mods 1 and 2; Aircraft Float Light Mk 6 Mods 0-2

AN-Mk 4
Length: 13 inches
Diameter: 3 inches
Weight: 2 pounds

Burning time: 3 to 3.5 minutes
Time from impact to ignition: 8 to 12 seconds
Release altitude: Under 500 feet
Visibility: Night - 6 to 7 miles



AN-Mk 5
Length: 19 inches
Diameter: 3 inches
Weight: 4 pounds

Burning time: 15 to 17 minutes
Time from impact to ignition: 8 to 12 seconds
Release altitude: Under 500 feet
Visibility: Night - 6 to 7 miles


Uses:  These signals are employed as follows:

-To determine the drift of the plane from which the signal was dropped.
-To mark an object to which an aircraft desires to call attention of a surface vessel.
-To determine the wind direction before landing.
-To mark the landing deck on aircraft carriers for night landings.
-To mark the location of the surface of the water for emergency night landings.


Description:  The Night Drift Signal AN-Mk 4 has an ogival shaped, die-cast nose with a lug on one side so that the signal will turn and not strike the bottom in shallow water, while the Night Drift Signal AN-Mk 5 Mod 1 has a flat die-cast nose.  In both cases the die-cast nose contains a water-impact fuze.  The bodies of both signals are made of hollow wooden cylinders, with one end tapered, on which the tail assembly is mounted.

The pyrotechnic mixture is formed into pellets approximately four inches long and 1.25 inches in diameter, with a 0.022-inch hole concentric with the longitudinal axis through which the delay fuse passes.  One pellet is used in the AN-Mk 4, and three pellets are used in the AN-Mk 5 Mod 1.  The pellets are enclosed in a pyrotechnic tube to keep the hygroscopic material from absorbing moisture through the wooden body.  Originally, pure tin was used for this purposed\l but in recent lots lead and zinc have been substituted.  The nose end of the signal is closed with a paraffin-treated sealing disc, while the tail is sealed with a metal cap.

Aircraft Float Light Mk 6 Mod 0 consists of four Drift Signals AN-Mk 5 Mod 1 which are contained in a square wooden body and burn successively.  The box is 20.25 inches long and 5.125 inches square.  The weight is 16 pounds, and the burning time is 45 minutes.  The float light is released by hand from an altitude of from 300 to 5,000 feet.  It gives off a grey smoke and a flame 10 or 12 inches high.  The Aircraft Float Light AN-Mk 6 Mod 2 is ignited by a pull igniter which is pulled when released.  The light can be dropped from an altitude over 5,000 feet.


Operation:  When launched from aircraft, the drift signal falls nose-down.  On impact with the surface of the water, the paraffined paper sealing disc is broken and the water drives the firing pin up against the primer.  The flame from the primer ignites the time fuze which runs the length of the hole through the center of the pyrotechnic pellets in order to give the drift signal enough time to return to the surface and right itself.  The time fuse ignites a length of quick match which, in turn ignites the starting mixture and then the pyrotechnic pellets.  The gases evolved by the pellets break open the pyrotechnic tube and force out the cap which seals the discharge tube in the tail.  A bright flame 12 to 15 inches high and a white smoke are produced.  These are visible for six to seven miles on a clear night.


Remarks: These signals may be used for day signals, but under certain conditions observation is difficult.

The Mod 2 is a moisture-proofed version of the Mod 1.

Retro-Rocket Drift Signals

No picture available

General: These 3-inch rockets are designed to be fired aft from a plane to eliminate the effect of forward motion, allowing the signal to fall straight down.  This is called retro-firing.


Description: The rockets have the 3-inch Heads Mk 5 Mod 1 and use the Motors Mk 2 or Mk 3.  With the Motor Mk 2, they weigh 4.8 pounds; with the Motor Mk 3, 4.6 pounds.  They use the Launcher Mk 2.


Operation:  Firing of the rocket motor initiates a delay train in the signal in the head, which delay sets off the flare 10 to 20 seconds later.  The motor separates from the head during the free fall, and the signal hits the water and floats on it, burning from 10 to 15 minutes.

Navy Flares

1 1/2 Minute Parachute Flare

No picture available

Length: 18.75 inches

Diameter: 2.24 inches
Weight: 4.31 pounds

Burning time: 1.5 minutes
Light intensity: 110,000 candlepower

Color: White
Maximum release altitude: 1,200 feet

Rate of fall after ignition: 550 feet/min

Use:  It is used to illuminate an area for emergency night landings by certain commercial-type aircraft in use by the Navy.

Description: The flare is issued in a hermetically sealed aluminum case called a projector tube.  One end of this tube is closed by a metal cap and sealed by a gasket. The other end narrows down into a small knob with an electrical terminal in the extreme end.  The tube is cylindrical for most of its length.

The projector tube contains an inner case and a propelling charge of black powder.  The inner case contains an ejection charge, the pyrotechnic candle, and a parachute.  The ejection charge is in the after end of the inner case, and the delay fuse and interrupter mechanism are mounted on the outside of the same end of the inner case.

The electrical terminal at the end of the projector tube is connected through a toggle switch in the pilot's compartment to the lighting system of the plane.


Releasing: The projector tube, which is constructed as an integral part of the flare, is fixed by clamp bands to a bracket in the after end of the fuselage, where the firing circuit is connected when the flares are loaded.  The projector tube remains in the bracket when the flare is released or expelled by closing the switch in the cockpit.

Operation:  When the electrical circuit is completed in the cockpit, the propelling charge is ignited and the inner case is forced out of the projector tube.  The propellant ignites the delay fuse, which burns until the inner case is approximately 40 feet from the plane and then, through an explosive lead-in, ignites the ejection charge which, in turn, forces the pyrotechnic candle and attached parachute from the inner case.  Simultaneously, the ejection charge ignites the candle.

An interrupter mechanism between the delay fuse and the ejection charge in the inner case prevents the functioning of the flare until the inner case has left the projector tube and is clear of the plane.

Remarks:  A proprietary item, this flare has a commercial designation of "1 1/2 Minute Parachute Flare Mk 1 Mod 1", but this Mark designation is not that of the Navy.

Mk 4 and Mods

  

Length: 25 inches

Diameter: 4.75 inches
Weight: 18 pounds

Burning time: 3 minutes
Light intensity: 300,000 candlepower

Color: White
Maximum release altitude: 1,200 - 5,000 feet

Rate of fall after ignition: 350 feet/min

Use: Primarily, this flare is used to illuminate an area to permit the landing of aircraft.  Occasionally, it is used for reconnoitering, bombing, and blinding anti-aircraft defenses.

Description: The complete flare consists of a parachute and illuminant contained in a shellac-impregnated chip-board tube closed at the ends by chip-board discs which are held in place by gummed cloth and sealed with paraffin.  There are two metal steadying bands fastened around the case, against which the steadying forks of the bomb rack rest.  The complete flare is issued in a waterproof metal container.

Operation:  The Navy Flare Mk 4 may be released from bomb racks or shackles, from an adapter, or manually.  As the flare is dropped from the plane, the arming plate of the rip cord is retained by the plane and the rip cord is pulled from the side of the flare case to which it is fastened by gummed cloth tape.  As the flare continues to fall, the rip cord, which is wound around a wooden spool inside the of the flare case, is unwound, tearing away the end of the flare case.  The end disc and spool fall away as the parachute tube is pulled from the flare case and retained by the rip cord.  The parachute is pulled out of its tube by the weigh of the illuminant and flare case, which causes the parachute and parachute shrouds to straighten out.  When the parachute and parachute shrouds are fully extended, a small cord attached to the release key pulls the release key down, allowing the rip cord to slip through the key, and the flare falls free.

An ignition wire is attached to the suspension cable in such a manner that it is pulled before the cable is fully extended.  Four friction wires are attached to the ignition and run through primer cups of match compound.  This ignites a double quick-match train, which burns down the outside of the illuminant case and ignites the primer composition, which, in turn, ignites the first fire and illuminant.  When the parachute opens, the illuminant is pulled out of the flare case, and flare case falls clear.  full suspension and ignition occur about 30 to 50 feet below the plane.

 

Next Time: Drift Signals and Navy Flares (Part 2)