SA01 - Explosives and Propellents Flashcards
Definition of Primary Explosives.
Substance, or mixture of substances used to initiate a detonation or a burning reaction
Required characteristics of Primary Explosives
- Stability over long period of time.
- Optimum sensitivity to applied stimulus
- Optimum output of the required kind
- Compatibility with materials
- Safety in loading and handling
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2 types of explosive Inititators
- Detonators/ Disruptive
- Ignitors/ Igniferous
Name some primary explosive compounds
- Lead Azide
- Lead Styphnate
- Lead Dinitro Rescorcinate
- PETN
- Von Herz mixtures
- ASA compound
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What does ASA (F2 detonator) composition consists of?
- Lead Azide - 68%
- Lead Styphnate - 29%
- Aluminium powder - 3%
Definition of Detonation
An extremely rapid chemical change with the evolution of heat and gas, accompanied by a violent disruptive effect and intense blast.
Definition of High Explosive (HE)
Any explosive which once initiated decomposes almost instantaneously into its original molecular structure by the passage of a detonation wave through it, with a subsequent production of heat and gases and the liberation of great energy
Definition of Low Explosive (LE)
- An explosive substance, which decomposes rapidly through combustion with the evolution of heat and flash, and generates a large quantity of gaseous products
– Burning rate up to 300m/s
Define Velocity of Detonation (VoD)
The rate, in metres per second, at which the wave of detonation passes through an explosive substance.
Define Figure of Insensitivity (FoI)
A relative number based on the ability of an explosive to remain insensitive to impact.
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Types of Low Explosives
- Gunpowder or Black Powder
- Propellants
- Pyrotechnics
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Examples of Secondary High Explosives
- CE (Composition Exploding) or Tetryl
- TR1 (Tetryl Replacement 1)
- TNT
- RDX
- PETN
- Picric Acid
- Comp B
- PE4
- C4
- HMX
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Composition of TR1
RDX 98.75%, Wax 1.25%
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Composition of Comp B
RDX 59.5%, TNT 39.5%, Wax 1%
What is OCTOL?
HMX 70%
TNT 30%
List the 5 purposes of additives used in HE
- Increase sensitivity
- Improve stability
- Increase blast effects
- Improve moldability
- Decrease sensitivity
Types of de-sensitisers
- Wax
- Aluminium
- TNT
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Composition of PE4
RDX 88%
Plasticiser 12%
What is Phlegmatizing?
When an agent is added to the explosive to stabilize or desensitize it.
Main types:
- Wax
- Oil
- Alcohol
- Water
Purpose of Sensitisers
When added to a basic material or a mixture, confers on it the required degree of sensitivity to shock or friction.
Two types of taggants used with explosives
- Detection taggants (help the dog find it before it functions)
- Identification taggants (help identify after the item has functioned)
What is the purpose of additives used in HE?
To confer it to the required degree of sensitivity to shock or friction.
What are the three types of plasticisers used in HE?
- TNT
- Liquid Paraffin
- Petroleum Jelly
Definition of propellent
An explosive which, by controlled burning, provides the gas pressure required to give motion to a projectile or missile.
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List 2 categories of (service) propellents
- Liquid
- Solid
Types of Liquid propellent
- Mono propellant (Ignited by electric means)
- Bi-propellant (Ignited by own reaction)
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Types of Solid propellant (modern smokeless propellant)
- Colloidal (Single, Double, Triple Based)
- Composite
What are all service propellants based on
Nitrocellulose (NC)
Types of Colloidal Solid Propellant
- Single-base propellants (consists of NC)
- Double-base propellants (NC & NG)
- Triple-base propellants
Where is Single base propellant used?
- Small Arms propellants, including heavy machine guns
- Secondary charges for mortars
- Igniters
Advantages of Double Based propellants
- Easily ignited
- Higher energy rating than single-base
- Higher flame temperature
- Higher burning rate
Disadvantages of Double based propellants
- Can cause excessive weapon erosion
- More dangerous to manufacture
- More costly to manufacture
Where is double base propellant used?
- In cordites
- In the form of ballistite for primary cartridges in mortars
- For small arms cartridges where high bulk energies are required
Properties of triple based propellants
- cooler than double-base propellants and therefore has a reduced muzzle flash
- lower bulk energies than double-base propellants
- They are more difficult to ignite
What are composite propellants?
Physical mixture of fuel and oxidant, with binders. They do not contain NC.
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Types of Additives used in propellants
Remember CDF LAMPS
C - Coolants
D - De-coppering agents
F - Flash inhibitors
L - Surface lubricants
A - Anti-wear additives
M - Surface moderants
P - Plasticisers
S - Stabilisers
What is Carbamite used as?
Surface moderant
Name 2 De-coppering agents
- Lead
- Tin
What are 3 ways to control the burn rate?
- Propellant composition
- Shape of propellant
- Size of propellant
What are 3 types of burning rates?
- Degressive burning
- Neutral burning (constant burning)
- Progressive burning
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Shapes of degressive burning
- Cord
- Flake
- Strip/ Ribbon
E.g. - SAA, Mortar, RKT Boost motors
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Shapes of Neutral/ constant burning
- Tubular
- Cogged
- Star Centre
E.g. - RKT Motors
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Shapes of Progressive burning
- Rosette
- Multi-Tubular
E.g. - Artillery, Tank, High-Velocity (HV) ammunition
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Remember the Propellent shapes
Slide 59 of the power point
What are the Australian propellant code?
Prefixed AR (Australian Rifle), then 4 numbers denoting;
First digit - Physical shape.
Second digit - Deterrent coating.
Last 2 digits - Single or Double-base propellant
Who discovered NG and when?
Italian Chemist Ascanio Sobreno in 1846
requirements for propellants
- Give regular ballistics
- Not produce excessive flash or smoke
- Must not cause undue erosion
- Must be relatively easily ignited
- Must be stable for storage under worldwide conditions
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What does guncotton consist of ?
Nitrocellulose, Nitric Acid and cotton fibres.
What does ballistite consist of?
camphor(wax), NC, NG.
What does cordite consist of ?
NC, NG and petroleum jelly.
Definition of pyrotechnic
A pyrotechnic composition is a chemical, or a mixture of chemicals which when ignited, burns at a controlled rate liberating energy and producing a reaction which can be converted into the desired effect.
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What 4 effects do pyrotechnics produce?
- Heat
- Light
- Smoke
- Sound
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Definition/ purpose of delay compositions
- A device which provides a time delay for a burning train of inflammable composition between events.
- Delays can be from milli-seconds to several seconds to several minutes.
OR
- To provide a pyrotechnic delay between two igniting or explosive events.
Memorise either one of the deifinitions
What is the purpose of dark ignition?
- To avoid observation of exact location of weapon
- Avoid dazzling the gun layers at night when fired from multiple and automatic weapons
2 groups of incendiary compositions
- Metals
- Combustible fluids
Composition of priming compositions
- Potassium Nitrate,
- Powdered silicon,
- Sulphurless mealed gunpowder
What are simulators used for?
Simulators are used to provide simulated battle noises and effects during training
Makeup of pyrotechnic composition
- Solid fuels
- Oxidants
- Various additives
3 means of initiating an explosive
- Mechanical (Mortar primary cart)
- Electrical (Elec det)
- Igniferous (non-elec det)
Three types of ignition systems
- Berdan - Cap and Integral Anvil
- Boxer - Cap and separate Anvil
- Rim Fire
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Cap composition mixtures consists of ?
- Primary Explosive
- Sensitiser
- Oxidiser
Two oxidants used in Illumination compositions
- Barium Nitrate/ Potassium Nitrate (White light)
- Sodium Nitrate (Yellow Light)
What are the chemical constituents of Illum and Signal compositions?
- Fuel (usually magnesium)
- Oxidant (for oxygen supply)
- Binder
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What produces Red colour in Smoke and signal?
Strontium nitrate, oxalate
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What produces Yellow colour in Smoke and signal?
Sodium nitrate
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What produces Green colour in Smoke and signal?
Barium nitrate, chlorate
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What produces Blue colour in Smoke and signal?
Copper carbonate, chloride, oxychloride
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What produces White colour in Smoke and signal?
Barium nitrate/ potassium nitrate mixture
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What produces Orange colour in Smoke and signal?
Calcium nitrate
What is the role of tracer compositions
Indicate the trajectory of a projectile.
What are the 4 design requirements for the Tracer
Composition
- Luminosity
- Strength
- Consistency of performance
- Ease of ignition
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2 types of signal composition
- ones that produce light of a distinctive colour
- ones that produce coloured smoke
Advantages of adding Aluminium to HE.
- Takes no part in the initial stages of detonation
- Absorbs energy & lessens the release
- Reinforcing action due to exothermic (produces heat & energy) interaction with some gaseous products of explosion
- Increases blast effect
Types of compositions
- Igniter
- Priming
- Incendiary
3 types of Igniters/ priming compositions
- Gunpowder
- Organic Substances combined with oxidants
- Mixtures that produce slag with little or no gas
Types of delay compositions
- Gas-producing
- Gas-less
Types of EO that may contain incendiaries
- Grenades
- Projectiles
- SAA
- Aircraft bombs
- Pre-set charges
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Purpose of smoke
- Screening
- Signalling
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Types of screening smoke
- Tactical
- Defensive
2 types of screening smoke agents
- WP
- Berger compositions
Advantages of WP
- Immediate effect on burning.
- Excellent screen produced (Excellent Infra-red screening agent)
- No priming or ignition devices required
Disadvantages of WP
- Pillaring effect on bursting.
- Severe burns.
- Harassing effect on eyes, nose and throat.
- Fire risk.
- Expensive method of filling.
- Isolation in storage and transportation.
Importance of smoke derieved from phosporous
It is a excellent infra-red screening agent
2 types of smoke compositions
- Zinc powder and zinc oxide with carbon tetrachloride
- Zinc powder and zinc oxide with hexachlorethane
Definition of Explosion
An explosion is the violent and rapid decomposition of energetic material to produce energy (heat) and gas which will lead to violent pressure and rupturing of any confining structure.
Definition of Deflagration
SUBSONIC combustion that usually propagates through thermal conductivity (hot burning material heats the next layer of cold material and ignites it).
Definition of Detonation
Involves a SUPESONIC exothermic front accelerating through a medium that drives a shock front propagating directly in front of it.
2 Types of HE
- Primary
- Secondary
Classification of Explosives
- Propellents
- Pyrotechnics
- HE
Requirements of Military Explosives
- Performance
- Sensitivity
- Stability and behaviour in storage
- Water resistant
- Consistency
- Thermal behaviour
Factors influencing explosions
- Quality of initiating source
- Nature of explosive
- Mass of explosive
- Unit density of explosive
- Degree of confinement
What are some ways to initiate explosives
- Direct heat/flame
- Percussion and stabbing
- Friction
- Electrical
- Shockwave
- Electromagnetic fields
- Laser
- Chemical reaction
What is Brisance?
The shattering effect of explosion
Factors affecting VoD
- Density of charge
- Charge diameter
- Degree of confinement
- Strength of detonator
What is burning to detonation?
It occurs when there is an abrupt acceleration of the flame front until it becomes a shock wave
What is Figure of Power (F of P)?
The ability of an explosive to displace or shatter the surrounding medium
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2 incendiary metals
- Aluminium
- Magnesium
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Define Igniter Compositions
Mainly used for propellant or pyrotechnic systems. They produce hot flames, usually accompanied by sparks and hot gasses, for relatively short times.
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Ideal properties of smoke compositions
- Immediate in effect.
- Unaffected as far as possible by climate/weather.
- Persistent.
- Non Anti-Personnel.
- Non Incendiary.
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Additives used in HE
- Sensitisers
- De-sensitisers
- Aluminium
- Stabilisers
- Plasticisers
- Taggants
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Characteristics of priming compositions
- Easily ignited.
- generate high heat.
- not burn too quickly or violently.
- be compatible with the mixture used.
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Ingredients of Greek fire
Naptha, Sulphur, Pitch
Ingredients of gunpowder
Potassium Nitrate (Saltpeter), sulphur, resin/charcoal
