Part 1 - Aircraft Bombs and Pyrotechnics; Chapter 20: Navigation Flame Float Mk I (Obsolescent)Part 1 - Aircraft Bombs and Pyrotechnics; Chapter 20: Navigation Flame Float No. 3 Mk I (Obsolescent) and No. 3 Mk II (Service)
Part 1 - Chapter 20
Aircraft Pyrotechnics

Navigation Flame Float Mk II, and Mo. 4 Mk I, and Message Carrying Flame Float Mk I (Service)

Fuzing Integral striker mechanism
Color markings Body, strut supports, strut, and protecting cap painted red; tail cone painted yellow
Over-all lenght 23.4 in.
Body diameter 5.9 in.
Filling Calcium phosphide
Filler weight 1.8 lb.
Total weight 11.8 lb.
Effective illumination 6 min.

Description: The Flame Float Mk II consists of two main parts, a body and a contai-ner. The body is a cylindrical casting, to one end of which three strut supports are rive-ted. A cylindircal strut is riveted to the supports. Secured to the fin by a securing wire is a punch to which is attched an instruction tag. The body is thickened at the nose end, and has an attached conical nose of thin sheet steel. A protecting cap is fitted over the nose, and a safety pin passes through holes in both the cap and nose.

The container consists of a sheet-metal cylinder, to one end of which is attached a sheet-metal tail cone. The opposite end of teh container is closed by a cap. The cap is apertured and carries a correspondingly apertured spigot and a wire gauze spigot socket on the side facing the tail cone. Passing axially along the container is a central tube, one end of which is soldered to the narrow end of the tail cone, while the other end fits into the socket. Near the tail end, the tube is closed by a sealing cup, projecting from which is a punch sleeve closing by a paper cap. On the side opposite the spigot the cap carries a diaphragm, which retains a striker. The striker is bored to receive the safety pin.

The lower part of the container is filled with granular calcium phosphide, which is held in position by a closing disc. This material surrounds the slotted portion of the central tube. Beyond the closing disc the annular space between the container and the central tube forms a sealed buoyancy chamber.

Functioning: Before the float is dropped, the punch is removed from the strut by cutting the securing wire, and the sealing cup on the punch sleeve is punctured with it. After the sealing cup has been broken, the flame float must be dropped from the aircraft immediately.

On dropping from an aircraft, impact with the water crushes the nose of the float and causes the striker to penetrate the sealing disc. At the same time the securing wires holding the container ot the body are broken, and the container and tail cone re forced away from the body. The buoyancy chamber maintains the tail cone uppermost in the water. Water enters the aperture in the cap, and passes through the gauze socket and the slots in the central tube into the calcium phosphide. The phosphine generated on en-try of the water passes upwards through the central tube, from which it emerges through the hole pierced by the punch through the sealing cup, and, on contact with the air, takes fire spontaneously.

Remarks: The inner body of the Navigation Flame Float No. 4 Mk I is identical to the inner body of the Float Mk II.

The Message Carrying Flame Float Mk I is almost identical to the Navigation Flame Float Mk II in dimensions and construction. The essential difference is that a message container is suspended in the buoyancy chamber by a fixing wire secured to a plug, which is screwed into a bush in the tail cone. The plug is provided with a handle to faci-litate its removal from the bush, and a washer on the plug insures a water-tight joint. An arrow and the words MESSAGE HERE are painted on the tail cone to direct attention to the message.

Figure 91 - Navigation Flame Float Mk II

Part 1 - Aircraft Bombs and Pyrotechnics; Chapter 20: Navigation Flame Float Mk I (Obsolescent)Part 1 - Aircraft Bombs and Pyrotechnics; Chapter 20: Navigation Flame Float No. 3 Mk I (Obsolescent) and No. 3 Mk II (Service)