American Projectiles and Explosives
American High Explosives (Part 2)
HBX
HBX is a new mixture designed to replace Torpex in depth bombs. It has been loaded in the Flat Nose Bomb AN-Mk 54 Mod 1. HBX is 40% RDX, 38% TNT, 17% Aluminum powder, 5% desensitizer. Tests indicate that it will be about 95% to 100% as powerful as Torpex, that it will definitely be less sensitive than Torpex in both Laboratory Impact and Bullet Impact, that it will be slightly more sensitive in these respects than TNT, and that it will be about the same order as Composition B.
A difficulty with Torpex and HBX is that they produce gas and build up pressure in the case during stowage. It has been discovered that 0.5% by weight of calcium chloride added to the mixture will absorb all the moisture and eliminate the production of gas. It has been recommended that this percentage be added and that the resulting mixtures be designated Torpex 3 and HBX 1.
Composition A
Composition A is a mixture of 91% RDX and 98% plasticizing oil. The oil content is sufficient to desensitize the mixture and lubricate it enough to allow it to be pressed into A.A. shells, which will probably be its principal use. It is less sensitive than TNT in both drop and bullet impact tests. It is appreciably more brisant and powerful as is indicated by its velocity of detonation of 27,000 feet/second at a density of 1.62. Its Laboratory Impact Value is 105. Its Ballistic Impact Value is over 100. Its color may be white or buff, depending upon the color of the oil.
Tetrytol
Tetrytol is a mixture of Tetryl and TNT (70/30 is a frequent ratio). It is designed to obtain a Tetryl booster that may be cast. This mixture is slightly less powerful and less sensitive than Tetryl. Its particular use is in burster tubes for chemical bombs, in demolition blocks, and in cast shaped charges. It cannot be used where the loaded item is immersed in hot explosive, as are the auxiliary boosters in the loading of Army bombs, because it will be remelted by the heat and separation will result. It is approved for use in all other boosters.
Its rate of detonation is 24,000 feet/second at a density of 1.6. Its Laboratory Impact Value is 45. Its Bullet Impact Value is 65. Its color is yellow.
Pentolite
Pentolite is a mixture of TNT and PETN, usually 50/50. Its chief uses have been in small shell loading, in grenades, and in cast shaped charges. It has a very high shaped-charge efficiency. It is not as stable as TNT in stowage, and separation of PETN may occur. Efforts should be made to keep it cool. Its sensitivity is such that it cannot be drilled, and the fuze cavities in shells that must be drilled are poured with 90/10. It is about the same sensitivity as Tetryl in drop tests, and more sensitive than Torpex to bullet impact. Its brisance and power are equivalent to Composition B.
At a density of 1.65, its rate of detonation is 24,000 feet/seccond. Its Laboratory Impact Value is 47. Its Bullet Impact Value is 48.
Ednatol
Ednatol is a mixture of 57% EDNA and 43% TNT, designed to ease the shortage of RDX. In the near future, it will be loaded as a substitute for Composition B in large G.P. bombs and fragmentation bombs. It is somewhat more powerful than TNT and comparable in sensitivity. It becomes soft enough to pour at 80 degrees Celsius and it is, therefore, cast. It is entirely stable in stowage.
At a density of 1.6, it has a velocity of detonation of 24,300 feet/second. Its Laboratory Impact Value is not given. Its Bullet Impact Value is 83. Its color is yellow.
PTX-1
PTX-1 is a new ternary explosive that is undergoing tests and may be adopted for loading in shells, bombs, grenades, mines, demolition blocks, and shaped charges. It is a mixture of 30% RDX, 50% Tetryl, and 20% TNT. This mixture gives a very high explosive equal to Composition B and Pentolite, and superior to Tetrytol and Ednatol. It is less sensitive than Tetrytol and more stable.
Its velocity of detonation is 24,200 feet/second at a density of 1.66. Its Laboratory Impact Value is 40 (est.). Its Bullet Impact Value is not given. Its color is yellow.
PTX-2
PTX-2 is another ternary explosive mixture undergoing study for possible future use. It consists of 43.2% RDX, 28% PETN, 28.8% TNT. It is slightly more sensitive in drop and bullet impact tests than Composition B, but a little less sensitive than Pentolite. It is mroe brisant than any of the binary mixtures now used, which would include Composition B, and is about 10% more effective than Tteryl as a booster. It may be used as a booster, as a main charge for fragmentation ammunition, and as a shaped charge. Its melting point is such that it will be cast.
Its velocity of detonation is 26,200 feet/second at a density of 1.69. Its Laboratory Impact Value is 50 (estimated). Its Bullet Impact Value is not give. Its color is yellow.
Composition C
Composition C-3 is the only one of the Composition C series now in production, though quantities of the others may be found int he field. It is 77% RDX, 3% Tetryl, 4% TNNT, 1% Nitrocellulose, 5% MNT (Mononitrotoluol), 10% DNT (Dinitrotoluol). The last two, while they are explosives, are oily liquids and plasticize the mixture. The essential difference between Composition C-3 and Composition C-2 is the substitution of 8% Tetryl for 3% RDX, which improves the plastic qualities. Composition C-1 was 88.3% RDX and 11.7% plasticizing oil. The changes have been made in order to obtain a plastic composition that would meet the requirements of an ideal explosive for molded and shaped charges and that would maintain its plasticity over a wide range of temperatures and not exude oil. Composition C-3 is about 1.35 times as powerful as TNT.
The velocite of detonation is 26,000 feet/second at a density of 1.58. Its Laboratory Impact Value is 98. Its Bullet Impact Value is over 100. Its color is brown.
PEP-3
This is a new plastic explosive being tested for future use. PEP-3 is a mixture of 86% PETN and 14 plasticizing oil. PEP-2 was 85% PETN and 15% oil, but it was a little too soft. PEP-3 is about 90% as powerful and brisant as Composition C, but its stowage stability and plastic range are much better. Its sensitivity is about the same as Composition C, though it has much less tendency to burn.
Picratol
Picratol is a mixture of 52% Explosive D and 48% TNT. It is currently used in the 2000-lb S.A.P. Bomb M103 and is under consideration for appliance in other Army A.P.s and S.A.P.s. Picratol's stability is about equal to that of Explosive D and TNT.
Its velocity of detonation is 22,875 feet/second at a normal loading density of 1.625. Brisance tests, peak pressure tests, and impulse tests indicate that Picratol's destructive force is somewhat less than that of TNT, but greater than that of Explosive D.
Cyclotol 70/30
Cyclotol 70/30, a mixture of 70% RDX and 30% TNT, closely resembles Composition B except for the altered proportions of the components, and is designed as a replacement for Pentolite. It will not, however, have Pentolite's resistance to flame. Though results of tests are not available, Cyclotol may be anticipated to be more sensitive than Composition B, but considerably less than Pentolite.
Tritonal
Tritonal is composed of 80% TNT and 20% Aluminum powder and is contemplated for use in some 4,000-lb Light-Case Bombs AN-M56, in the JB-2, and in several G.P. bombs (Army 500- and 1000-lb G.P.s), where maximum blast effect is desired. Tritonal is cast, segregation of the aluminum being prevented by a pellet loading technique.
Its Laboratory Impact Value is 89; its Bullet Impact Value is 64; and the velocite of detonation is 18,000 feet/second at a density of 1.7.
Mercury Fulminate
Mercury Fulminate is an initiating explosive that may be used as either a primer or a dtonator. It may be detonated by flame, friction, or percussion, and in turn detonate a booster; or it may be mixed with other materials to form a primer composition and used to ignite a propellent charge. Its melting point is much too high for it to be cast, and it is loaded by being pressed into caps. It has one disadvantage for military use in that it will decompose in stowage at tropical temperatures and at the end of about three years may be rendered useless.
Compared to high explosives, it has a lower power and brisance, a fact which is indicated by its velocity of detonation of 16,500 feet/second at a density of 4. Its Laboratory Impact Value is 8. Its color is light yellow.
Lead Azide
Lead Azide may be used where a detonation is caused from flame, but Mercury Fulminate is generally preferred where the cap is to be set off by a firing pin. It does have a distinct advantage over Mercury Fulminate in being completely stable in stowage at elevated temperatures.
Its rate of detonation is of the same order as Fulminate, 17,500 feet/second at a density of 4. Its Laboratory Impact Value is 19. Its color is white.
DDNP
This is an initiating explosive which has been used for some time in commercial detonating caps and is now being used to some extent in military types. It is more insensitive to shock than Mercury Fulminate and Lead Azide, though it may be detonated by a sharp blow. It will, therefore, probably be used only where it will be set off electrically or by miner's safety fuse.; It has an advantage in being more powerful than other initiating explosives and being comparable in strength to Tetryl. If unconfined, flame will cause it to flash but will not detonate it. This, combined with its insensitivity to shock, makes it much more safe to handle.
Next Time: Introduction to U.S. Projectiles
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