Description
The Navy Flare Mk 5 illuminates an area for reconnoitering, bombing, or landing.
The complete flare consists of a parachute, an illuminant, and an impregnated chipboard case. It is closed on the parachute end by several layers of chipboard discs held ill place by gummed cloth tape and sealed with paraffin, and on the fuze end. which contains the Ensign Bickford fuse, by a metal cover. There are two metal steadying bands fastened around the case, against which the steadying forks of the bomb rack rest. The complete flare in its case is issued in a waterproof metal container.
In later models a new type of shock absorber eliminates the use of lead snubbers. The cable pulls through a connection in which friction absorbs the shock of the parachute opening.
Functioning
The setting of the Ensign Bickford time delay fuse is made by turning the lock screw on the metal firing mechanism housing to the desired delay, which is indicated on the bevel of the fuze-setting ring. The numbers indicate the vertical distance the fuze will drop before igniting. When the correct setting is obtained, the firing mechanism is secured by screwing the lock screw until its point is buried in the flare case.
When the flare is released from the plane, the arming plate is retained on the plane, the rip cord is torn from the side of the flare case, and the cover on the fuse end is flipped off. The rip cord is attached to the snap cord that passes around a lug on the firing lever and is secured to the fuse block. As the flare continues to fall, the snap cord is pulled, overcoming the lever spring and cocking the firing lever. When a tension of approximately 38 pounds is reached in the snap cord, it breaks, releasing the firing lever and the lever spring, then driving the firing lever back Against the fulminate of mercury primer. The flare now' falls fire.
The primer ignites the black-powder pellets in the fuze plunger. The expanding gases from the burning black powder propel the sharp point of the plunger radially outward into the Ensign Bickford time fuse. There are three small holes near the point of the plunger which allows some of the flame to escape from the inside of the plunger into the powder of the Ensign Bickford fuse that causes its ignition. The time fuse bums its predetermined length at the rate of approximately 12 inches per 60 seconds, and ignites the quick match under the firing block.
The flash produced by the quick match ignites the firecracker fuse stapled to the ignition composition. The gases evolved when the ignition composition begins to burn force the end discs out at the parachute end, then expel the parachute and illuminant. The parachute tube, which is of split construction, falls away; the parachute opens; and the retention cable slides through the trigger snap on the end of the shroud lines until it reaches the cable stop. A short length of cable on one side of the cable stop suspends the flare case, and a longer length on the other side suspends the illuminant This keeps the case from dropping as a missile hazard. The sudden shock caused by the contact of the cable stop with the trigger snap is taken up by a shock absorber. This is done by pulling a cable containing lead balls, called snubbers, through a hole which is of smaller diameter than the diameter of the snubbers. As each snubber passes through the hole, part of it is sheared off, thus absorbing part of the shock. The last ball is of much greater diameter and acts as a stop.
See Also
Nothing else to see.
Source(s)
OP 1664, Volume 1 - US Explosive Ordnance (1947)
USNBD - Bombs and Fuzes, Pyrotechnics (1945)
