AIRCRAFT-LAUNCHED SMOKE AND FLAME MARKING DEVICES

LEARNING OBJECTIVE: Identify the physical and functional description of aircraft-launched smoke and flame marking devices. Recognize the methods used to launch them.

Smoke and flame marking devices are pyrotechnic devices dropped on the ground or on the water's surface to emit smoke and/or flame. Reference points established by these devices serve a variety of purposes. They can be used to determine wind direction and approximate velocity, mark the location on the surface for emergency night landings, establish an initial contact point for continued search for a submarine, or locate target areas in antisubmarine warfare.

MK 25 MODS 2 AND 3 MARINE LOCATION MARKER

The Mk 25 Mods 2 and 3 (fig. 4-9) marine location markers are launched from aircraft or surface craft. They are launched from aircraft to provide day or night reference points for marking the course of enemy submarines in antisubmarine warfare operations. They are suitable for any type of sea-surface reference-point marking that calls for both smoke and flame for a period of 10 to 20 minutes. Mods 2 and 3 function identically. The only significant difference is that Mod 2 contains two seawater-activated batteries and two related squibs while Mod 3 contains a single battery and squib.

Physical Description

The Mk 25 marker consists of a cylindrical outer tube about 18.5 inches long and 2.9 inches in diameter. A valve assembly is fitted into the projecting chimney at the marker's nose end. The smoke and flame are emitted from this opening. At the opposite end is a

Figure 4-9.-Mk 25 marine location marker.

heavier aluminum base assembly to which the outer tube is crimped. The heavy base end causes the marker to float in the water with the chimney out of the water and the base in the water.

Within the base assembly is a Mk 72 Mod 0 seawater-activated battery (two batteries in the Mod 2). The battery is shielded from water contact by two plugs fitted into 1/2-inch holes on two opposite sides of the base assembly. A rigid cover (arming plate), held in place by a retainer ring, is recessed into the base end. An arrow in the center of the arming plate indicates its safe or armed position. The words SAFE and ARMED are stamped into the base rim. Also, a machined notch in the rim at the armed position helps during night use. When the arming plate is in the safe position, it physically blocks the base plugs internally to prevent them from being accidentally pushed in. When in the armed position, the arming plate no longer blocks the base plugs, allowing them to be pushed in at the appropriate time. A black rubber G-ring circles the base assembly approximately 1/4 inch from the crimp, which holds the outer case.

Functional Description

To activate the seawater battery, the base plugs are pushed in before the marker is actually launched. The marker is ignited by an electric squib, and power is supplied by the seawater-activated battery (two batteries and two squibs in Mod 2). When the marker enters the water, seawater enters the battery cavity and serves as an electrolyte, causing the battery to produce a current that activates the squib. The squib ignites the starter mix, which, in turn, ignites the red phosphorous pyrotechnic composition. Gas buildup forces the valve assembly from the chimney in the nose, and yellow flame and white smoke are emitted. Burning time averages 13.5 to 18.5 minutes. Although this marker is normally used in seawater, it can be used in inland bodies of fresh water by using table salt and following the procedures outlined in Pyrotechnic, Screening, Marking, and Countermeasure Devices, NAVSEA SW050-AB-MMA-010/NAVAIR 11-15-7.

Launching Methods

Currently, there are two methods of launching the Mk 25 marker-by hand or by sonobuoy launcher. To launch by hand, rotate the base arming plate clockwise to the armed position. Push the base plugs into the battery cavity, located in the marker base, and throw the marker into the water. It functions as previously discussed.

If the base plugs (one or both) of a marker are disturbed so the watertight integrity of the battery cavity is compromised and the marker is not launched immediately, a marine marker adapter kit (Mk 34 Mod 0) must be installed. The Mk 34 Mod 0 adapter kit is also used when the marker is launched from sonobuoy launchers. The adapter kit fits over the base end of the marker, and, when properly installed, seals the battery cavity. The adapter kit is installed by rotating the marker base arming plate to the armed position and pushing the base plugs into the battery cavity. Remove the black G-ring and install the adapter kit around the marker base so the seal plugs on the leaf-spring ends cover the holes into the battery cavity. Insert the U-pin to hold the adapter in place. To hand-launch a marker with a Mk 34 adapter kit installed, remove the U-pin and the adapter and throw the marker into the water.

Before launching the Mk 25 marker from sonobuoy launchers, you should install a Mk 34 adapter kit (fig. 4-10) on the marker. The adapter kit provides a safe environment for the marker until the last possible moment before launch. Because of the physical difference in size between the Mk 25 marker and the sonobuoy launch tubes, a sonobuoy launch container (SLC) and spacer assembly (fig. 4-10) is used to launch the Mk 25 marker from a sonobuoy launcher.

The Mk 25 marker, with the Mk 34 adapter kit installed, is installed into the cavity half of the split foam spacer assembly section with the U-pin of the Mk 34 adapter in the UP position. Then, remove the U-pin and place the other half of the split foam spacer assembly section over the marker, which completely encloses the marker. The foam spacer assembly containing the marker is then installed into the SLC against the obturator. Foam pads are installed, and the end cap is locked into slots in the SLC, retaining the assembly

Figure 4-10.-Spacer assembly and sonobuoy launch container.

inside the SLC. A JAU-1/B cartridge is installed in the SLC, and the loaded SLC is installed in the sonobuoy launcher aboard the aircraft.

To launch the Mk 25 marker, the JAU-1/B cartridge is initiated through the aircraft circuitry. It develops sufficient gas pressure inside the SLC to force off the SLC end cap and expel the foam spacer assembly containing the Mk 25 marker. Once out of the SLC, the split foam spacer assembly is separated by the airstream, freeing the marker. The airstream then separates the Mk 34 adapter kit from the marker, allowing them to fall to the water as separate units. Upon entry into the water, the marker functions as previously discussed.

MK 58 MOD 1 MARINE LOCATION MARKER

The Mk 58 Mod 1 marine location marker (fig. 4-11) is designed for day or night use in any condition calling for long-burning, smoke and flame reference-point marking on the ocean's surface. In addition to being used for antisubmarine warfare, it is used for search-and-rescue operations, man-overboard markings, and as a target for practice bombing at sea. The marker produces a yellow flame and white smoke for a minimum of 40 minutes and a maximum of 60 minutes. It is visible for at least 3 miles under normal operating conditions.

Physical Description

The Mk 58 Mod 1 marine location marker consists of a cylindrical tin can approximately 21.78 inches long and 5.03 inches in diameter. The can contains two pyrotechnic candles of a red phosphorus composition. The ignition end of the marker has three holes-two for smoke and flame emission and one for water to enter the Mk 72 Mod 1 seawater-activated battery. Adhesive foil disks hermetically seal the two emission holes. A reinforced adhesive foil strip with a rectangular pull ring hermetically seals the battery cavity hole. The adhesive foil seals are protected during handling and shipping by a replaceable polyethylene protective cover.

Launching Methods

The Mk 58 Mod 1 marker maybe hand launched, externally launched from suitable aircraft bomb racks by using breakaway suspension bands, or launched from sonobuoy launchers by using a sonobuoy launcher container (SLC) and the appropriate foam spacer. No matter how the marker is launched, the protective cover, the pull ring, and reinforced adhesive foil strip over the battery's cavity are removed.

When launching the marker from a sonobuoy launcher, you remove the protective cover and pull ring and reinforced adhesive foil strip. Then, load the marker onto the bomb rack. After securing the marker

Figure 4-11.-Mk 58 Mod 0/1 marine location marker.

to the bomb rack, attach the pull ring to an arming wire, which is attached to the bomb rack. When the marker is released from the bomb rack, the arming wire retains the pull ring and removes the foil strip covering the battery's cavity. When submerged, the Mk 72 Mod 1 battery is activated by seawater. Current from the battery initiates a Mk 13 electric squib, which ignites the starter composition of the first pyrotechnic candle. The composition ignites the starter pellet, which, in turn, ignites the first candle. When the first candle is nearly burned out, its heat ignites the transfer time fuze which carries ignition to the second candle starter composition. This starter composition initiates the second pyrotechnic candle.