Torpex

Torpex is a secondary explosive 50% more powerful than TNT by mass. Torpex is composed of 42% RDX, 40% TNT and 18% powdered aluminium. It was used in the Second World War from late 1942. The name is short for 'Torpedo Explosive', having been originally developed for use in torpedoes. Torpex proved to be particularly useful in underwater munitions because the aluminium component had the effect of making the explosive pulse last longer, which enhanced the destructive power. Torpex was used only in critical applications, e.g. torpedoes and the Upkeep, Tallboy and Grand Slam bombs. It was also used in the Operation Aphrodite drones. Torpex has long been superseded by H6 and PBX compositions. It is therefore regarded as obsolete, so Torpex is unlikely to be encountered except in the form of legacy munitions or unexploded ordnance.

Development

Torpex was developed at the Royal Gunpowder Factory, Waltham Abbey, in the United Kingdom as a more powerful military alternative to TNT. RDX was developed in 1899. Though very stable and serving as the reference point by which the sensitivity of other explosives are judged, it was too expensive for most military applications, and reserved for use in the most important products, such as torpedoes. Aluminium powder was also added to the mix to further enhance the effect. Although both RDX and TNT have a negative oxygen balance (RDX would require 9 oxygen atoms to oxidize all of its carbon and hydrogen but has only 6, while 2 molecules of TNT together would need 33 oxygen molecules but have only 12). However the aluminum powder is superheated by the explosion and combines with environmental oxygen in a highly exothermic reaction which generates additional heat and thus greater explosive product volume and expansive force. This produces a longer and more damaging explosive pulse than high explosive alone in a process similar to a thermobaric weapon. Beeswax was also added to reduce sensitivity to shock and impact. Later, beeswax was replaced with a petroleum-based product, and calcium carbonate was added as a moisture absorber to reduce the production of hydrogen gas under high humidity.

See also

• Minol
• Composition H6
• Tritonal
• Hexanite
• Explosives used during WW II

References

• Gannon, Robert. Hellions of the Deep: The Development of American Torpedoes in World War II. University Park, Pa.: Pennsylvania State University Press, 1996. ISBN 0-271-01508-X.

• Rowland, Buford and William B. Boyd. U.S. Navy Bureau of Ordnance in World War II. Washington, D.C.: Government Printing Office, 1947.