Composition B, colloquially "Comp B", is an explosive consisting of castable mixtures of RDX and TNT. It is used as the main explosive filling in artillery projectiles, rockets, land mines, hand grenades and various other munitions. It was also used for the explosive lenses in the first implosion-type nuclear weapons developed by the United States.
The standard ratio of ingredients (by weight) is 59.5% RDX (detonation velocity of 8,750 m/s) and 39.4% TNT (detonation velocity of 6,900 m/s), phlegmatized with 1% paraffin wax. Most commonly it is described as 60/40 RDX/TNT with 1% wax added.
- Density: 1.65 g/cm3
- Velocity of detonation: 8,050 m/s
Composition B was extremely common in United States and other western nations' munitions and was the standard explosive filler from early World War II until the early 1950s, when less sensitive explosives began to replace it in many weapons systems. Some NATO-approved munitions suppliers such as Mecar have continued to use Composition B in their products.
Composition B is related to Cyclotol, which has a higher proportion of RDX (up to 75%).
Modern TNT-free alternatives
IMX-101 is slowly replacing Comp B in the US military.
- Cooper, Paul W. (1996). Explosives Engineering. Wiley-VCH. ISBN 0-471-18636-8.
- Atom Bombs: The Top Secret Inside Story of Little Boy and Fat Man, John Coster-Mullen, 2003
- Nuclear Weapons FAQ section 8.1.1: The Design of Gadget, Fat Man, and "Joe 1" (RDS-1), accessed August 10, 2009
- Military Specification MIL-C-401
- Mecar website