Mk 76 and BDU-33 practice bombs

Learning to bomb without bombs

Every bombing skill has to be practised, and dropping live bombs on a training range is expensive and dangerous. The answer is the practice bomb. Navy ordnance training divides them into two kinds: subcaliber bombs, much smaller and lighter than the weapon they stand in for, and full-scale practice bombs that match a service bomb’s size and weight. [1] The Navy’s Mk 76 and the Air Force’s BDU-33 are two such subcaliber bombs.

A small blue teardrop

The Mk 76 Mod 5 is a 25 lb solid metal casting shaped like a teardrop, with welded-on tail fins and a hole bored down its centre for a signal cartridge. It hangs from a single lug and works on impact only: when it hits, a firing pin sets off the cartridge. It is painted blue. [1]

The Air Force describes the BDU-33 in almost the same words: a 25 lb, non-explosive, teardrop-shaped practice bomb that simulates the Mk 82Mark 82 general-purpose bomb OrdnanceThe 500 lb low-drag bomb that is one of the most common air-dropped weapons in the world, with conical, Snakeye or ballute tails. and Mk 84Mark 84 general-purpose bomb OrdnanceThe 2,000 lb heavyweight of the Mark 80 series, dropped by the thousand in Desert Storm and the warhead of the GBU-10 and GBU-31. in their low-drag configuration. On impact a firing pin strikes the primer of a signal charge so that the hit can be seen and scored. [2] Two cartridges do the marking: the Mk 4 Mod 3, which gives a flash and smoke and is used mainly at night, and the CXU-3A/B, which gives a dense white smoke for day use. [2] The Navy’s smaller BDU-48/B, a 10 lb thin-cased bomb with box fins, takes the same cartridges and simulates retarded delivery instead. [1]

Full-size practice

When crews need the real size and weight, full-scale shapes take over. The Navy uses inert-filled Mk 80 bombs, painted blue, and the BDU-45/B practice bomb, which takes the same retarding fin as a Mk 82Mark 82 general-purpose bomb OrdnanceThe 500 lb low-drag bomb that is one of the most common air-dropped weapons in the world, with conical, Snakeye or ballute tails.. [1] [3] The Air Force buys the 500 lb BDU-50C/B and the 2,000 lb BDU-56/B, each made to match the drop trajectory of a live Mk 82Mark 82 general-purpose bomb OrdnanceThe 500 lb low-drag bomb that is one of the most common air-dropped weapons in the world, with conical, Snakeye or ballute tails. or Mk 84Mark 84 general-purpose bomb OrdnanceThe 2,000 lb heavyweight of the Mark 80 series, dropped by the thousand in Desert Storm and the warhead of the GBU-10 and GBU-31.. [2] The inert Mk 80s give loading crews as well as pilots full-scale training. [1]