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| BRITISH EXPLOSIVE ORDNANCE |
| Part 1 - Chapter 20 |
| Aircraft Pyrotechnics |
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Navigation Flame Float No. 3 Mk I (Obsolescent) and No. 3 Mk II (Service) |
| Data |
| Fuzing | None; water initiated |
| Color markings | Yellow over-all |
| Over-all lenght | 18.5 in. |
| Body diameter | 2.9 in. |
| Total weight | 2.5 lb. |
| Filling | Calcium magnesium phosphide |
| Effective illumination | 5 min. |
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Description: The Flame Float No. 3 Mk I has a cylindrical tinplate body, the after end of which has four attached tail fins. The tail end of the body is closed by a tail cover having a central hole. The neck of the tail cap is closed by a thin rupture disk to which is secured a small pillar having a ring passing through it. The forward end of the body is closed by a cast-iron nose having a central water-inlet hole. The nose is contained in a tin-plate cover, having a central hole covered by a tear-off seal to which is secured eit-her a ring or an eyelet. Inside the body is a perforated zinc central tube surrounded by a swansdown bag containing calcium magnesium phosphide. Cotton wool is packed around the tail end of the bag, and a layer of glass wool is located between the bag and the iron wire gauze. The charcoal is provided to absorb any slight traces of gas which may be given off while the flame float is in storage. The tail end of the body comprises the buoyancy chamber of the flame float. |
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Functioning: Before dropping, the tear-off seal at the nose is removed. When drop-ped, the tail rupture disc is broken and the float rises to the surface. Water enters through the water-inlet hole in the nose, passes through the perforated zinc tube, and soaks through the flannel finger into the swansdown bag, where it reacts with the calci-um magnesium phosphide to give off spontaneously inflammable phosphine. The phos-phine, so generated, escapes through the broken rupture disc and takes fire on contact with air. |
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Remarks: Should either of the seals be broken while in storage, the damaged flame float must be removed to a dry place where the possibilty of its catching afire is an ac-ceptable risk pending final disposal. |
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The Float Mk II differs from the Mk I in that a rear seal and tear-off cord are substi-tuted for the tail rupture assembly of the Mk I. The long perforated tube of the Mk I is considerably shortened in the Mk II. |
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Figure 92 - Navigation Flame Float No. 3 Mk I |
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