[Tony Williams]

Comparing explosives is not simple as there are different aspects to their effectiveness and one which is good in one respect may be less good in another. This is what I put in Flying Guns – World War 2: Development of Aircraft Guns, Ammunition and Installations 1933-45 which I wrote with Emmanuel Gustin:

The types of high explosive chemicals used in shells did vary, although not by as much as might be thought, as different names were used for similar substances. The basic HE in general use was TNT, as used in the Great War. This was often mixed with ammonium nitrate to create Amatol; cheaper but just as effective, except for increased susceptibility to damp. Some use was also made of picric acid, or Lyddite, another First World War explosive.
Before the Second World War, more powerful substances were introduced into service. One of these was PETN, also known as Penta or Penthrite. The problem was that this was generally felt to be too sensitive to use by itself, as it was inclined to be detonated by the shock of firing (although this did not deter the Japanese, as we have seen). It was accordingly usually desensitised by adding about 15% of Montan wax to produce Penthrite Wax, or Nitropenta. An alternative use was to mix PETN with TNT or Amatol to form one of the Pentolites; this actually helped with pouring TNT and Amatol into shells, as by themselves they solidified too quickly and tended to leave holes. Another new explosive, as powerful as PETN but less sensitive, was RDX (Research Department eXplosive), which was also known as Cyclonite or Hexogen.
Aluminium powder was often added to HE, as this both increased the brisance (shattering effect) and enhanced the incendiary effect; an important issue as, for example, some 90% of RAF bomber losses in the war were attributed to fire rather than structural damage. A typical German HEI mix was 63% Penthrite, 29% aluminium and 8% wax, although these proportions did vary. Shell fillings for the 30 mm M-Geschoss typically consisted of 75% Hexogen, 20% aluminium and 5% wax. The (rarely used) M-Geschoss for the BK 3.7 contained a mix of 45% Hexogen, 40% TNT and 15% aluminium. Much use was made of HA.41, a mixture of 80% Cyclonite and 20% aluminium.
Allied explosive fillings included Pentolite, Torpex (a mixture of RDX, TNT and aluminium) and Tetryl or CE (Composition Exploding). The Japanese used several types, with TNT, Pentolite and Cyclonite all being recorded, by themselves or in various combinations. The Soviets used a mixture of RDX and aluminium.
These explosives exhibited some differences in the characteristics, as shown below. The most powerful have not been much exceeded in destructive power since.

I then include a table of characterstics, which I can't copy-and-paste here, but it shows that Hexogen has about 50% more power than TNT (measured as calories per gram x cc per gram) and 100% more brisance or shattering effect, measured by power x velocity of detonation x density. However, it was twice as sensitive.

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