Ballistic bomb

The ballistic bomb (pressure bomb, manometric bomb) is used to study the burn-up properties of a -> Gunpowder or -> Propellant charge powder. It consists of a pressure-resistant (dynamic loading up to about 1000 MPa (10000 bar) hollow steel body that can be bolted... 

When the geometry of the propellant is known, the linear burning rate and the pressure exponent of a propellant can be determined experimentally in a ballistic bomb. 

A complete gas pressure curve can only be plotted with the aid of piezo-quartz or other pressure recorder in conjunction with an oscillograph (-> Ballistic Bomb). 

The basis data for internal ballistic calculations are thus obtained (also -> Ballistic Bomb - Burning Rate). As an example for the calculation of a double base gunpowder ) composition... 

The determination of the combustion pressure of propellants (or pyrotechnic compositions) at constant volume conditions is performed in a specially designed closed vessel. The vessel has a combustion chamber with a volume up to 2.5 dm and it can withstand the dynamic pressure of as much as 5000 bar. Such vessels are so-called closed bombs, ballistic bombs, or manometric bombs. 

Pepin Lehalleur (1935) Assembly of Calorimeter Landrieu-Malsallez and Bomb of Burlot-Malsallez (p 44, Fig 5) Brisance Determination by Kast, Quinan and Chalon Methods (63-64) Trauzl Block Test (French Modification) (64-66) Mortar Test (Epreuve de tir au mortier) (66-67) Ballistic Pendulum... 

Taylor (1952), Measurement of Detonation by Dautriche (pp 24-28) and by Rapid-Photography Methods (28-32) Heat of Explosion by Calorimetric Bomb (40-2) Temperature of Explosion (43-7) Power or Strength of High Explosives by Trauzl Lead Block Test, Ballistic Mortar Test and pendulum Test (185-86)... 

The principal input and output tests used by the US at the time of publishing NOLTR 1111(1952) included Drop Ball Testers (two types) Sand Bomb Apparatuses 100, 200, 360 500 gram Condenser Discharge Apparatus Torsional Ballistic Pendulums (two types) Drop Ball Test Set Mk 135 with Chronograph Thermocouple Drop Ball Test Set Mk 136 with Chronograph Gas Explosion Chambers (two types) Gas Volume and Impulse Apparatus Pressure Bomb Apparatus and Hopkinson Bar Apparatus (Ref 11, pp 9-2 9-3, Table 9-D... 

The 60/40 mixt was cast-loaded to a density of 1.65 its mp 65-70°, Expln Temp 264° higher Brisance, by Copper Cylinder Crusher Test 100% (PA=100%) Power by Ballistic Mortar 96% (PA=100) Deton Velocity by Dautriche Method 7050m/sec Impact Sensitivity with 15kg Weight 14cm (max wt for no expins) Friction Sensitivity 60kg (max pressure betw two rubbing surfaces for no explns). Used, under the name Type 98, in Navy Bombs,... 

The 70/30 mixt had Expln Temp 237-46° Brisance by Sand Test 102% TNT Power by Ballistic Mortar 109% TNT Rifle Bullet Test 20% detonations and Impact Sensitivity by PicArsn Test 12.5 inches (TNT 14). It was reported to be toxic, not very stable, and reactive with metals in the presence of moisture. Used pressed by Army and Navy as an Auxiliary Booster in some Bombs and Shells (Ref 1, pp 31 32 and Ref 5, p 365)... 

Shotoyaku (Amatol). A mixture of AN 50 TNT 50% of brown color, d (cast) 1.59, mp 81°+, Brisance by Plate Dent Test 52% TNT Expin Temp 265° (dec in 5 secs) Impact Sensitivity BurMinesApp 2-kg Wt 95cm Power by Ballistic Mortar 124% TNT Rate of Detonation 6430m/sec (Ref 8, p 16). Was used in same1 Bombs and in Semisteel (high C cast iron) Shells. Was reported to be found in some Navy Mines (Ref 1, p 27 Ref 5, p 372)... 

The burn rates of propellants are determined in a strand burner (Crawford bomb/ acoustic emission technique) at various pressures using an inert gas for pressurization. This data, when fitted in the empirical relation r = a.P" provides the pressure index n and the coefficient a. This technique is highly useful as a first approximation and is extensively used for propellant screening and quality control. The bum rates at different pressures are also determined by static testing in a ballistic evaluation motors (BEMs) and burn rates are typically scaled up from 1-5% for full scale motors. 

In the United States a mixture of 60% cyclonite and 40% TNT was used under the name of Cyclitol as a filling for aerial bombs. The density of the cast explosive was 1.65-1.70, its rate of detonation 7800 m/sec, and in the ballistic pendulum it gave a value of 130 (100 for TNT). In the United States this mixture is considered to be only a little more sensitive to impact than TNT with a stability similar to that of cyclonite. This does not agree with T. Urbanski s [5] investigations according to which the sensitiveness to impact of such a mixture, in a powdered form, and its ignition temperature (225°C) approximate to the corresponding values for tetryl. 

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