Submarine Emergency Identification Signal Mk 2 Mods 1 and 2; also Submarine Emergency Signal, Star, Mk 3 Mods 0 an 1

Length, inches

18.0

Diameter, inches

Burning time, seconds

Delay, seconds

Color

Red, yellow, or green

Use: These signals are used for submarine emergency identification, whether submer-ged or surfaced.

Description: The signal consists of a cylindrical aluminum case containing the grena-de-type Pyrotechnic Candle Mk 3. The bottom end contains two delay elements. A sing-le-star candle is attached to a parachute by an asbestos cord.

Operation: The shell is projected from the standard submarine emergency identifica-tion signal ejector, using compressed air as the propellant. The shell is fired by a lug at its base which projects beyond the side of the shell and rides in a groove in the ejector tube. As the shell is forced through the tube, the extended lug reaches the end of the groove just before the base of the shell passes the muzzle door. The tripping lever is pul-led back, thereby cocking and releasing the firing pin lever and firing pin. The firing pin strikes the primer, and the flash from the primer ignites a time fuse. The time fuse burns while the signal is rising to the surface. The delay ignites the grenade-ejection charge, which ejects the signal to a distance of approximately 250 feet. At the summit of the trajectory, the delay train flashes into the signal-ejection charge and causes the para-chute suspended star to be ejected.

Remarks: The Mk 2 Mod 2 is obsolescent being replaced by the Mk 3 Mods 0 and 1. The Mk 3 Mod 0 has a slightly different method of expelling the inner grenade. The maxi-mum launching depth is 160 feet.

The Mk 3 Mod 1 is similar to the Mk 2 Mod 1 except for the following: (1) a delay of 54 to 59 seconds, (2) a maximum launching depth of 285 feet, and (3) a sturdier con-struction to withstand pressure at a lower depth.

Figure 217. Submarine Emergency Identification Signal Mk 2 Mod 2