I.B. 25-lb. Mk I and II (Obsolete)
No Image Available Filler and Weight
NA,
Body and Overall Weight
NA, 25 lb.
Color
Dull red over-all, with Black bands separated, red band painted around the nose
Type of Round, DODIC
I.B., NA
Description:
The bomb Mk I consists of a cylin¬drical steel tube secured to a hollow, sharp-pointed nose by a nose adapter (built up externally to streamlined form by a cardboard fairing), a column of seven closed containers, termed fire-pots, accommodated in the body tube, a flanged base adapter which affords a mounting for a cap holder, a. tail cone with a cylindrical tail vane secured to it by four vane supports, and a tail tube which accommodates a striker pellet, with a shear wire and creep spring, and a safety rod. Each of the seven fire-pots consists of a cylindrical container made of magnesium alloy and formed with a central tube, which communicates, through a fire hole, with a recess in a central boss on the base of the container. The container is closed by a magnesium alloy lid, which has a shallow central recess in its outer side. Holes through the lid place this recess in communication with, the interior of the con¬tainer. The ignition cap contains a layer of gun¬powder and a layer of detonating composition. The central tube of each of the fire-pots houses a delay charge and is surrounded by a delay charge and priming; charge for the termite and magnesium filling, which occupies the remainder of the annular chamber in the fire-pot. A loop of quick match extends into the bore of the central tube and has its two ends carried out through the slots in the tube.
Use:
When the bomb using the Parachute and Striker Attachments No. 1 Mk I is released, the cover pulls the chute out.
Functioning:
When the bomb using the Parachute and Striker Attachments No. 1 Mk I is released, the cover pulls the chute out. The chute opens and pulls the snatch rod against the action of the spring until the striker rod retaining balls escape into the annular recess in the retaining sleeve. The striker rod then moves down against the striker pellet. On impact, the inertia of the rod and pellet combine to shear the shear wire, overcome the creep spring, and pierce the ignition cap, igniting the blowing charge and blowing the base adapter and complete tail and parachute assembly from the body tube. The quick match, which passes through the lid and into the central tube of the rearmost magnesium alloy fire-pot, is also ignited, and, in turn, the quick match ignites the delay charges in and around the central tube of the tire-pot. While the central tube delay charge is burning through, the outer delay charge initiates the surrounding priming charge, which, its turn, ignites the incendiary composition around it. Meanwhile the central delay charge burns through and fires the ejection charge in the base of the fire-pot. This has the effect of ejecting the activated fire-pot from the bomb and also igniting the quick match of the second fire-pot, etc. Each ejected lire-pot will continue to burn for approximately 10 minutes; the mag¬nesium alloy container and lid being consumed, Finally, the quick match in the lid closing the nose of the bomb is ignited by the last ejection charge and initiates the priming charge, which, in turn, ignites the incendiary composition of the nose, and provides an additional fire source. When used with the Parachute and Striker Attachments No. 1 Mk II, the parachute is blown out of the cylindrical shroud on the tail and the chute opens, freeing the striker mechanism. Functioning after this is same as that with Attachments No. 1 Mk I.
Munition Components:
  • Fuze Simple impact striker
  • Fuze Simple impact striker
  • Fuze Simple impact striker
Data Source:
OP 1665 Explosive Ordnance British
Munitions Tech Data Sheet:
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