Fragmentation Bomb Clusters

M1-Adapter M1: 100-pound size for six 20-pound Frag. Bombs AN-M41. It is 46.75 inches long and weighs 125 pounds. It has lugs for double-hook suspension only. The re-lease mechanism operates by means of a cartridge and firing mechanism.

Figure 263. Cluster Adapter M1, M1A1, and M1A2

M27-Adapter M14: 500-pound size cluster for six 90-pound Frag. Bombs M82. The adapter consists of two longitudinal steel tubes, 56 inches long, to which are welded four steel plates forming the support for the six bombs. The lower tube serves as the back-bone of the cluster; and the upper tube carries the suspension lugs, the buckles for the releasing straps, and the adapters for the nose and tail fuzes. The Nose Fuze M111A2 or M155 is used; however, there is no mechanical time fuze in the tail.

The cluster may be adjusted to release the bombs immediately or, through the use of mechanical time fuzes, to dischare the bombs 5 to 92 seconds after the release of the cluster from the plane. If it is intended that the cluster is to open immediately, the shear wire is cut after the arming wire is installed, and no fuze is used. The immediate opening of the cluster produces the most favorable impact pattern. The cluster must open at a minimum altitude of 1,000 feet in order that the bomb fuze may arm.

Figure 264. Typical Fragmentation Bomb Cluster
(Cluster shown is M26. See page 409)

M28-Adapter M51A1: 100 pound size for twenty-four 4-pound Frag. Bombs M83. It is a cylindrical sheet-metal case, which opens longitudinally, being hinged at the rear and closed by a nose cup. It is 47.35 inches long and 8 inches in diameter, and weighs 155 pounds loaded. It uses Fuze M155 or AN-M146.

These clusters are released from altitudes ot not less than 3,000 feet and not more 5,000 feet. Fuze settings for function after release are varied from five seconds at mini-mum release altitude to eight seconds at maximum release altitude. When the fuze fires, it releases the nose closing cup, allowing the adapter to open and release the bombs. The bombs scatter to form a pattern over an area of approximately 300 by 200 feet.

M28A1-Adapter M15A1: The Cluster M28A1 is the same as the M28, except that it incorporates a spoiler ring around the nose and a drag plate secured to the tail by four screws. These two devices were added because the dropping altitude for the M28 was limited by the high velocity attained by the clusters at high altitudes, resulting in damage to the butterfly when the cluster opened. When drag plates and spoiler rings are used, the recommended release altitude is 1,500 feet with a six-second fuze setting, or any higher altitude which will open the cluster at a height between 1,000 and 2,500 feet.

M28A2-Adapter M15A2: This A2 modification has a nwe locking cup, which is secu-red to the adapter by two slotted screws. Otherwise, it is the same.

M29-Adapter M16A1: 500-pound size for 90 4-pound Frag. Bombs M83. The contai-ner is like the M15, except for size. In the Adapter M16, the bombs are loaded in "wafer" assemblies. This cluster has a third single lug for British suspension.

M29A1-Adapter M16A2: This A1 modification has the new locking cap, secured to the adapter by two slotted screws. Otherwise, it is the same.

Remarks: For Navy usage, the Bureau of Ordnance recommends that the case-lock-ing bushing it has developed be used with all "Butterfly" fragmentaton clusters, including the M28, M28A1, M28A2, M29, and M29A1. One end of the bushing screws into the fuze adapter, and the other end is threaded internally to receive the fuze. The locking cup is retained positively by a safety wire which passes through a hole in the locking-cup tab and around a cotter pin placed in the bushing. When the fuze fires, the locking cup is blown into the cluster, shearing the loops safety wire and allowing the adapter to open.

Figure 265. Clusters for 4-pound Frag. Bomb M83