US Cluster Adapter, M23, M23A1




Cluster Adapters M23 are used in forming 500 pound aimable clusters of incendiary or chemical bombs. Clusters may be carried by planes equipped to handle 500 pound bombs. They are designed for use in high and medium altitude bombing, the flight characteristics resembling those of the Practice Bomb M38A2.

The cylindrical halves of the cluster wall are joined at the top by a suspension bar and at the bottom by a burster-shield support bar. Cluster bars, fitted into the end plates, hold the bombs in position inside the adapter. Ballast weights are bolted by studs to the front and rear of the adapter’s end plates. Nine steel straps, drawn tight and fastened by a metal connector, are attached to release buckles which are placed on alternate sides of the suspension bar. The buckles are held closed by two release wires attached to a release lever, which in turn is attached to a stud on the tail cone. The tail assembly is composed of a modified box-type fin on a conical support, with two tail-fuze adapters attached to opposite sides of the cone. The long stud, which extends through the rear ballast weight, supports the tail assembly.

The primacord wiring of the adapter is in two sections. A metal tube channels a 60 inch length of primacord from the forward end of the burster shield, through the tail cone, and into the base of the "long” fuze adapter. A 31-inch length extends from the tail cup into the "short" fuze adapter.

Bombs are clustered in two sections. 19 bombs in each, with the nose to the front of the cluster.




AN-M69 (NP, IM) Incendiary


AN-M69X (NP, IM) Incendiary


M74 (PT1, NP) Incendiary


E5R8 (H) Gas


M77 (HC) Smoke

Two mechanical time fuzes are used, one being placed in the ‘‘long’’ and one in the "short" fuze adapters. Two Fuzes M153 are now used, but are being replaced by two Fuzes M152.

Some lots of adapters were shipped without buckles and release wires, the release of the bombs being dependent on the severing of the steel strapping bands. The primacord from the "short" fuze is taped at a right angle to the primacord leading from the "long" fuze, to form one primacord assembly. Operation of either fuze would detonate the primacord extending the length of the cluster, thereby severing the steel strapping bands and releasing the bombs.

See Also

Tail, MT, M153


Collaborative Ordnance Data Repository

TM 3-400, Chemical Bombs and Clusters (1957)

OP 1664, Volume 2 - US Explosive Ordnance (1947)

OP 1664, Volume 1 - US Explosive Ordnance (1947)

USNBD - Bombs and Fuzes, Pyrotechnics (1945)