Summative - Target Analysis Flashcards
What is the definition of an explosion?
- An explosion is the violent and rapid decomposition of energetic material to produce energy (heat) and gas (1)
- which will lead to violent pressure rupturing of any confining structure
High explosives are split into two groups, what are they and give an example for each group?
Primary - Lead azide, mercury fulminate (sensitive to stimulus)
Secondary - Comp B, RDX
What factors affect the Velocity of Detonation (VoD) of explosives?
Degree of confinment,
Strength of detonation,
Density of Charge, and Diameter of Charge
Explain how burning to detonation occurs.
•Burning to detonation occurs when there is an abrupt acceleration of the flame front until it becomes a shock wave. (1)
•When explosives are confined in a tube and ignited at one end. The gas generated cannot escape, so pressure builds up the burning rate increases and pulses can
be generated which may accelerate the burning rate to sonic velocity.(1)
•A shock wave is the formed and the transformation to detonation is complete (1)
What are the advantages to a Fuel Air Explosion (FAE)?
FAE provides larger overpressures at greater distances
than HE would provide
Requires little or no oxygen in the molecular structure
therefore making a FAE explosion 3 to 5 times hotter than HE
In your own words, explain Rarefraction.
The area of low pressure immediately following the positive phase
In your own words explain Reflection
The blast wave is thrown back at an angle to its original path
In your own words, explain the definition of blast
A violent disruptive effect caused by an explosion.
From the explosion there is an evolution of heat
and gases and a shock front which emanates from the centre of the explosion.
What is the formula used for the Probability Product Rule?
PK= PHxPRxPL.
expressed as percentage
List the three levels of damage which an ammunition designer may wish to achieve in regards to Target Analysis?
Neutralisation, Destabilisation, Destruction
On the battlefield, people appear as many different targets. What factors affect their vulnerability and explain each of them?
•Attitude – their presented area
•Protection – the effects of their equipment, body armour including helmets, or the occupation of buildings
or field works
What are the two energy sources employed in ammunition design. Briefly describe each below?
Kinetic. (KE) Normally delivered in the form of a solid
missile which dissipates its energy on impact and requires no triggering device to control the energy release at the target.
Chemical. (CE) Delivered In the form of a substance,
with a considerable potential energy relative to its mass, which can liberate that energy when suitably initiated. Such materials are familiar as high explosives and the initiation mechanism as the fuze.
Overpressure from a chemical energy source (blast) is one of the four basic techniques used in the attack of aircraft in flight. What are the other three?
Kinetic energy missiles similar in principle to those used to attack people. (Bullets or fragmenting warheads).
Special kinetic energy missiles, eg Continuous Rod
Directed Energy warheads using shaped charge and
EFPs
List the standard criteria used in the defence industry for aircraft damage?
•KK-Kill The target suffers immediate and catastrophic
disintegration.
•K-Kill The target is destroyed in less than 10 secs.
•A-Kill The target is destroyed in less than 5 mins.
•B-Kill The target is defeated in less than 5 hours.
•C-Kill The target’s mission is not achieved (mission
abort).
•E-Kill The target may complete its mission but
needs repair before it can fly again.
What effect does altitude have on a blast warhead?
Higher the altitude the bigger the warhead
To be effective a blast wave requires a medium through which it can travel. As the medium becomes less dense, the effects of a blast warhead decrease.
Cluster disc warheads are one type of attack available in the engagement of aircraft in flight, name three others.
Fragmentation
Fragmentation and Blast
Shape Charge
What percentage of fragmentation in an anti-aircraft warhead is wasted?
<80%
In relation to the previous question, how can a fragmentation warhead be made more efficient?
They can be made more efficient by arranging the fragments and HE so that the fragments are projected in a narrow beam or band in one chosen direction (Preferential fragmentation).
Rolled Homogenous Armour (RHA) and Spaced Homogenous are types of armour. Name five other types?
.Ply •Face Hardened •Reactive – Explosive Reactive Armour (ERA) •Slat (BAR) •Composite (Chobham) •Reactive
Barrelling, Shattering and Lateral Stresses are possible causes of shot failure. Explain Shattering?
•Raising the hardness of a steel shot, whilst increasing
its compressive strength, makes the shot brittle. On impact severe tensile hoop stresses are set up in the nose of the shot (small cross sectional area).
•At high striking velocities, which raise the loading on
the shot, the shot nose can fail under these stresses and longitudinal cracks are formed along the length of the shot.
•The shot is said to “break up”, where effect is more catastrophic and the shot disintegrates, this is known as “shatter
Explain the damage assessment criteria Firepower (F) kill?
•tank is knocked out if the main armament is put out
of action; either because the crew has been rendered incapable of operating it,
•or because the armament or its associated equipment has been damaged, so as to render it inoperative and irreparable by the crew on the battlefield
What are the four Behind Armour Effects (BAE)?
Luminescence
Spalling
Heat/Fires
Overpressure
In a combined kinetic/chemical energy attack, what problem arises in relation to the chemical energy portion of the round?
Whilst no fuzing is required to allow the kinetic energy effect to penetrate the armour, the problem of initiating the CE source behind armour presents considerable difficulties to the projectile designer, due mainly to the intense shocks to which any initiating mechanism is subjected on initial impact and during penetration
Lengthening the barrel and rocket assist are two ways of increasing penetration of armour. Name the other three?
harder material
segmented rods
Reduce friction, making more aero dynamic
Severity of a casualty or wound type is dependent on what three factors WRT energy transfer?
- The actual amount of energy transferred
- Rate of transfer of energy from projectile to target
- Tumbling / yawing reduce energy transfer
To some extent, a designer can control fragment velocity by varying what?
•The amount of explosive behind the wall, and its
velocity of detonation.
•The charge density and velocity of detonation.
•The density of the wall material.
The ammunition designer can control the size of fragments obtained from a shell body by varying what design features?
Shell Material
Velocity of detonation
Density and placement of HE
Shell wall
How does the orientation of a projectile affect the distribution of fragments?
•With a conventional high explosive projectile the most effective ,distribution of fragments will be achieved when the axis of the projectile is vertical.
•As the axis moves away from the vertical an increasing
number of fragments is either lost in the ground or projected relatively harmlessly into the air.
Explain how a High Explosive Squash Head (HESH) attack defeats armour plate and what effect it causes?
•When a charge of high explosive is detonated on the
surface, a shock wave is transmitted through the plate.
•It is partially reflected at the rear face when it reaches the armour/air interface.
•The sudden reversal of direction of the shock wave
over-stresses the armour in the area of the rear face.
•Provided the charge overmatches the thickness of plate,
the result of the local over-stressing (by constructive interference) is to detach a scab of metal from the rear surface of the plate with a considerable velocity
Where is the point of initiation of a HESH round?
Rear
What is Reverse Impact Detonation (RID)?
When the explosive fill of a HESH round detonates before the fuze can produce detonation of the filling, the shock wave will be travelling in the wrong direction and will not produce the desired effect in the plate.
With regards to external ballistics, how is air resistance reduced when designing a kinetic energy round?
High Mass
High Velocity
Areodynamic
Small crossectional area
When an Armour Piercing Fin Stabilised Discarding Sabot (APFSDS) round is fired from a rifled barrel, how is the projectile rate of spin reduced?
With a slipping Driving band.
The sabot of an APFSDS projectile is difficult to discard since the low rate of spin provides insufficient centrifugal force. What forces are utilised to assist with discarding the sabot?
- Aerodynamic
* Residual gas pressure
What lengths to diameter ratios are applied to the following forms of stabilisation?
Spin- 7:1
Fin- 15:1
What factors affect performance of a shaped charge?
Cone diameter shape liner liner material stand off distance rate spin
What stand off distance achieves peak performance of a shaped charge?
5 Cone Diameters
Plate charges are less sensitive to variations in manufacturing tolerances. Penetration of at least one cone diameters can be achieved at what distance?
1000 cone diameters
