107. Float Flare Mk 15, Fig. 50, is a 150,000 candlepower floating pyrotechnic. It is laun-ched by hand, and burns five minutes with a yellowish flame some 26 inches high and four inches wide, five minutes after it is launched. The flare weighs 26 pounds, is appoxi-mately 37.2 inches long, has a maximum diameter of 6.5 inches, and is launched by two men. One pulls the safety ring as the other holds a safety lever while casting the flare overboard. The entire unit consists of a bomb-shaped pine wood body 32 inches long, closed at one end by a steel nose cap and at the other by a cone-shaped fuze housing appoximately five inches long. The fuze housing carries a 3.5-foot length of time fuze, which gives a delay of five minutes between then launching and the ignition of the pyro-technic candle. The candle, consisting of barium nitrate, aluminum, magnesium, and so-dium oxalate, is contained in a plastic tube 31 inches long and 2.75 inches in diameter, within the wood body. While burning, the flare floats in a vertical position, the water le-vel being nine inches from the top of the firing mechansim.

(a) Only limited operational tests in silhouetting ships with this flare have been made. It is established, however, that one flare placed some 1500 yards behind a torpedo boat will silhouette that boat for another vesselm at a distance of two miles in clear night weather. I has been found that such silhouetting is more efefctive with slight overcast or surface haze conditions prevailing.

(b) The placing of the flares in pattern, depending on the size and shape of the target and the atmospheric conditions, has also been studied. It is believed that three or more flares spaced at about 300-yard intervals, will satisfactorily silhouette a ship when vie-wed by another ship from the flank opposite. Specific details of pattern for practical use must be worked out by the various torpedo boat sqaudrons.

Figure 50. – Float Flare Mk 15

Operation

108. To launch Float Flare Mk 15, the man who is to launch it must hold the flare hori-zontally, with the fuze pointed outboard. The flare is held with the safety lever firmly pressed against the side of the case. A second man must then grip the pull ring of the safety pin, and withdraw it just before launching. Still holding the safety lever against the fuze housing, the first man then casts the flare overboard, to leeward whenever possible. The releasing of the safety lever will ignite the primer and the time fuze, and the flare will operate after a five-minute delay.

Stowage

109. General stowage instructions, as described herein in paragraphs 9 to 12, inclusive, apply Float Flare Mk 15. Precautions should be take not to expose these flares to direct sunlight or to excessive moitsure.

Packing

110. Float Flare Mk 15 is packed and shipped in an individual wood case. It should not be removed from the shipping case until ready to use. Future issues will be in individtual wa-tertight metal cases similar to six-inch powder tanks.

Safety Precautions

111. In handling and using Float Flare Mk 15, the following safety rules must be enfor-ced:

(a) These flares are for exclusive use by surface craft and must never be dropped from aircraft. A modification of this flare is now being designed for use by aircraft.

(b) In handling the flare, operating personnel should be instructed not to grasp it by its firing mechanism. A strong pull on the firing mechanism may detach that element from the rest of the flare.

(c) While launching, the operator must hold the flare horizontally, with the fuze housing pointed outboard, while the safety pin is being pulled.

(d) The safety lever must be held firmly against the side of the fuze housing and relea-sed only at the moment the flare is cast overboard. Should the safety pin be pulled and it be decided not to use the flare, the pin may be replaced only if the operator is certain that the lever has not been sufficiently released to prime the fuze.