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2.1.3(2) Flashcards

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1
Q

Define Explosion

A

An explosion is the RAPID DECOMPOSITION of energetic material to produce energy (heat) and gas which will lead to violent pressure rupturing of any confining structure

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2
Q

Define Deflagration

A

Is a technical term describing subsonic combustion that usually propagates through thermal conductivity (hot burning material heats below colder layer)

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3
Q

Define Detonation

A

Involves a supersonic exothermic front accelerating through a medium that drives a shock front propagating directly in front of it.

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4
Q

What is Velocity of Detonation? VOD

A

The rate, in metres per second, at which the wave of detonation passes through an EXPLOSIVE SUBSTANCE

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5
Q

VODs

A 
ANFO   4800 m/s
TNT      6950 m/s
CE         7160 m/s
PETN   8300 m/s
RDX      8400 m/s
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6
Q

Factors Affecting VOD

A

Density of charge
Charge diameter
Degree of confinement
Strength of detonator

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7
Q

Burning To Detonation

A

Occurs when there is a abrupt acceleration of the flame front, until it becomes a shock wave and the transformation to a detonation is complete

eg. Explosives confined in a tube, where gases cannot escape
Even unconfined explosives, if in sufficient bulk, may generate sufficient pressure to enable the remaining explosives to detonate

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8
Q

Probability Rule

A

Prob Kill = P Hit x P Reliability x P Lethality

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9
Q

Energy sources available for Ammunition Design

A

KINETIC energy

CHEMICAL energy

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10
Q

What is a Physical explosion

A

The catastrophic rupture of a pressurized gas/vapor-filled vessel by means other than reaction

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11
Q

…

A

…

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12
Q

Problems with KE and CE-combined ammunition?

A

The problem of initiating the CE source behind armour due to the shock on impact onto any initiating mechanism

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13
Q

Personnel - frag velocity is controlled by what factors? (3)

A

Amount of explosive behind wall
Charge density and VOD
Density of wall material

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14
Q

What are the types of Ballistic requirements for KE?

A

Internal ballistics
External ballistics
Terminal ballistics

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15
Q

How does a HESH round work?

A

Detonate HE in contact with armour
Shock wave travels through plate and reflects back
causes a tension wave
The tension wave meet the primary shock wave, resulting in a scab detaching from the rear of the plate

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16
Q

Scab size?

A

1.25 to 1.5 times size of weapon’s diameter

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17
Q

What is Reverse Impact Detonation for HESH?

A

If detonation occurs before the fuze can produce detonation of the filling, the shock wave will be travelling in the wrong direction

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18
Q

Describe how APFSDS works?

A

Shot fired from weapon
Slipping driving bands reduce spin
sabot is discarded through aerodynamic forces
Hits and penetrates through KE

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19
Q

(KE)
What are the 2 forms of stabilisation?
What are the ideal length:diameter ratios of a projectile applying to forms of stabilisation? (x:x)

A

Length:diameter
7:1 spin 15:1 fin(might be angles instead?)

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20
Q

How do Shaped Charges work, IOT defeat armour?

A
  • Achieved by hollowing out the front face of a slab of HE IOT give a conical shape.
  • The energy from the detonation is directed inward and forward as a GASEOUS JET.
  • A metal liner will travel forward with it
  • At an extremely high velocity.
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21
Q

Types of Explosions?

A

Physical (or mechanical)
Chemical
Nuclear

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22
Q

What are Primary Explosives?

Name 3 examples

A

A primary explosive is an explosive substance which is extremely sensitive to stimuli such as heat, friction and/or shock and which requires special care in handling.
Mecury fulminate, Lead Azide, Lead Styphnate

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23
Q

What are Secondary Explosives?

Name 2 examples

A

A secondary explosive is an explosive substance which is relatively insensitive to stimuli such as heat, friction and/or shock. (eDEOP)

RDX, TNT

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24
Q

Requirements for Military Explosives (6)

A
  • Performance
  • Sensitivity
  • Stability & behaviour in storage
  • Water Resistance
  • Consistency
  • Thermal behaviour
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25
Chemical Explosion
An extremely RAPID REACTION of a chemical system to produce heat and gas The sudden expansion of gases into a volume much greater than the initial one, accompanied by noise and violent movement
26
Nuclear Explosion
Sudden release of enormous quantities of heat by fission or fusion processes
27
# Define Blast Phases?
- 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. - Shock Front - Positive Pressure Phase - Negative Pressure Phase
28
Dynamic Pressure Incident Pressure
Dynamic Pressure Results from the high wind velocity & increased density of the air behind the shock front Incident Pressure Pressure exerted at right angles to the direction of travel of the shock front
29
Quasi Static Pressure Reflected Pressure
Quasi Static Pressure -Results when an explosion occurs within a structure creating overpressure; eventually settles to a slow decaying level  Reflected Pressure -Instantaneous build up of pressure occurring when a shock front strikes a rigid surface in it’s line of travel
30
2 types of waves created when contacting a surface (2) What is Mach Stem
Reflection Diffraction Mach Stem- reflected wave impacts original
31
Fuel Air Explosives (FAE) - Basic Principle?
The basic principle consists of: creating an aerosol cloud of fuel air mixture, by a bursting charge, which is then detonated to achieve an explosive effect. The blast wave formed inside the cloud and proceeds unabated to the edge of the cloud  The overpressure is therefore very high when the wave is an appreciable distance from the point of initiation
32
FAE - Types of Fuel (6)
- acetylene - butane - ethylene oxide - kerosene - propylene oxide - aluminium
33
Advantages of FAE (2+) Disadvantage
ADV -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 DIS-ADV -Strong winds would prevent the development of the optimal shape from the initial burst
34
Types of Targets for FAE (7)
``` Structures Concentrations of AFV and SP Guns Parked aircraft Minefield clearance Ships Bunkers / trenches Concentrations of troops in the open ```
35
Key Target types for target analysis? (3)
People Attack on Armour Aircraft in Flight
36
Types of Aircraft targets? (3)
Fast Moving Slow moving Helicopters
37
Standard Damage Criteria for A/C (6) Alternate (3)
``` KK-Kill immediate K 10sec A 5 mins B 5 hours C (mission abort) E complete msn, needs repair ``` F(t) permanently unable to fly C(t) Unable to continue E(t) needs to be grounded for repairs
38
Areas of Aircraft Vulnerability (8)
``` Airframe Aircrew Fuel cells Engines Power transmission systems Flight controls Avionics Payload ```
39
Reduction of Vulnerable Areas for A/C (6)
``` Armouring Burying sensitive components Concentrating sensitive components Duplicating components Separating Components Self sealing fuel tanks ```
40
Types of Warheads against aircraft? (7)
``` Blast Fragmentation (Inefficient --80% Wasted)80% Wasted) Fragmentation plus blast Special kinetic energy -Discrete rod -Continuous rod Shaped charges Sub--projectiles Cluster ```
41
Effects of Altitude (4)
Density Attenuation (weakening of shock wave) Miss Distance Altitude increase = Warhead increase
42
Fragmenting Warheads - How much is wasted? How to make more efficient?
>80% wasted, 50% in wrong direction Preferential Frag warhead direct the frag in a given direction
43
Pers - Most efficient mode of attack? (3)
- High probability of a hit - Rapid transfer of energy - No unecessary overkill
44
A WOUND is caused by the transfer of energy from fragment to body. The type of wound is dependent on what? (3)
- Amount of energy transferred - The rate of transfer - Tumbling/yawing of fragment
45
List the 3 Fragment producers (Frag design)
- Generic HE projectiles. - Pre notched containers. - Pre formed fragments.
46
Control of the fragments SIZE is ACHIEVED by: (4)
- Case material and its mechanical properties - Thickness of the wall - Quantity of explosive and its position in relation to the fragmenting case - VOD of the explosive.
47
What is Fragment VELOCITY controlled by?
- Amount of explosive behind the fragment wall - Charge density and velocity of detonation - Density of the wall material
48
What are the factors affecting performance of fragmentation? (4) Describe.
DOHA 1. DISTRIBUTION of frag: - Spin rate will influence but not pattern - Usually symmetrical on longitudinal axis - Angle of arrival 2. Orientation of projectile - Effective distribution when angle is vertical - Increasing amount of frag is projected into the air or ground as the angle changes 3. Height of burst - 2-4 metres is best - achieved by fuzes 4. Average area of exposed target - Target posture - Terrain - PPE
49
Factors affecting RATE of transfer? (4)
Mass Velocity Cross sectional area Stability of the fragment
50
6. Types of Armour Construction (7)
RSPFECS ``` Rolled homogenous armour Spaced homogenous Ply Face hardened Explosive reactive armour (ERA) Composite (Chobham) Slat (bar) ```
51
Tank Damage Assessment Criteria
M -Mobility kill F -Firepower kill (incl. main armament, ammo, pers) K -Completely destroyed
52
APC & MICV (IFV) assessment criteria
F - firepower kill | P - payload kill (Pers in the back)
53
6. List the 3 basic modes / methods of attack to defeat armoured vehicles and fortifications
KCC - Kinetic energy - Chemical energy - A combination of both
54
Explain Shot Failure - Barrelling
Direct compression failure in the shot material. The shot bellies at about its mid point  Increase in cross sectional area and the shot fails to push through.
55
Explain Shot Failure - 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, the shot nose can fail under these stresses and longitudinal cracks are formed
56
Explain Shot Failure - Lateral bending
 At high angles of attack the shot is subjected to severe lateral stresses, both particularly towards its rear end.  The effects of these stresses can be reduced by increasing the toughness of the shot towards its rear end and by fitting a toughened steel sheath over the rear end of the shot.
57
What are ways to Increase Penetration? (5)
- Lengthening of the BARREL - Lengthening the PROJECTILE - Rocket Assistance (RA) - Improve STEADINESS of shot - Use of segments long rod penetrators
58
HEAT - Factors affecting Shape Charges (5)
- Cone diameter - Shape of liner - Liner material - Stand-off distance - Rate of spin
59
Chemical Energy - Plate Charges
``` HEAT versus Plate Charge (EFP / SFF / Miznay Schardin) o Manufacture Tolerances o Greater Stand Off o Rate of Spin o Penetration o Lethality ```
60
Behind Armour Effects
BAE contribute to lethality of attack | Effects may be physical, psychological or physiological
61
What are BAE Effect types? (4)
SHOL Spalling Heat/fires Overpressure Luminescence
62
Methods of weapons/Delivery of shaped Charges (5)
GGMAM - Guns - Grenades - Mines - Aircraft bombs - Missiles
63
Factors taken into consideration in the defeat of armour (3)
- Accuracy - Reliability - Lethality
64
Description of Kinetic Energy
In the form of a solid missile/projectile, which dissipates it's energy on impact and requires no triggering device to control the energy release.
65
Description of Chemical Energy
In the form of a substance, with a considerable potential energy, relative to it's mass, which can liberate that energy when suitably initiated. Such materials are familiar as HE and the initiation mechanism as the fuze.
66
General Principles of HESH?
When the rebounding tension wave meets further primary shock waves this exceeds the strength of the plate, and a large scab is detached from the rear surface
67
HESH Scab size in reference to its diameter?
generally 1.25 to 1.5 times its own diameter Velocity of scab 30 - 130 metres pers sec
68
What is Reverse Impact Detonation (RID)?
Detonation occurs before the fuze can produce detonation of the filling, the shock wave will be travelling in the wrong direction
69
Secondary Effects from HESH? (2)
Anti -personnel | Damage to sensitive equipment
70
Types of armour that defeat HESH (4)
Spaced armour Skirting plates Grooved Reactive armour
71
HESH has good performance against what other targets?
- Emplacements - Pill boxes - Concrete Structures
72
Factors affecting Performance of HESH? (3)
- Calibre - Angle of Attack - Striking Velocity
73
Requirements for: Internal Ballistics External Ballistics (4) Terminal Ballistics (4)
High Velocity = a wide base for the propellant to work against and a low mass to overcome External - Small cross sectional area - High Mass - High Velocity - Aerodynamic design ``` TERMINAL Small cross sectional area High mass High velocity Hard material ```
74
Stabilisation Length:diameter ratios for Spin/Fin?
Length:Diameter ratio Spin - 7:1 Fin 15:1
75
What does the following mean? APCR APCNR APFSDS
- Armour Piercing Composite Rigid (APCR) - Armour Piercing Composite Non Rigid (APCNR) - Armour Piercing Fin Stabilised Discarding Sabot (APFSDS)
76
Parts of a APFSDS (see picture!) (5)
- Centring Band - Slipping Driving Band - Obturator - Sabot - Screw Thread
77
What are the two types of discarding sabots?
Petal | Pot
78
Developments for KE Projectiles
```  Move to DU - Self sharpening - Pyrophoric effect  Energetic propellants  Higher diameter: length ratios  Higher calibre (up to 140 mm)  Electromagnetic - hypervelocity projectiles ```
79
What is a Shape Charge?
A charge shaped so as to concentrate its explosive force in a particular direction
80
Parts of a HEAT Round (6) (look at picture!)
- PIBD Fuzing - Ballistic Cover - Empty Space and Shape Assist - Conical Liner - Detonator - Explosive
81
With a shaped charge the residual energy after penetration lies within what materials? (2)
- Unconsumed part of the jet | - Fragments of metal (spalling)
82
How do shaped charges achieve their effect?
Intense concentration of kinetic energy
83
What is the Secondary effect of Shaped Charges?
Anti-personnel effects from the fragmentation of the external casing
84
What are the FACTORS affecting the performance of shaped charges? (5)
- Cone diameter - Shape of liner - Liner material - Stand-off distance - Rate of spin
85
What are the ideal stand-off distances for shape charges? (2)
2 CD - little degradation | 5 CD - peak performance
86
Spin Compensation
Slipping driving bands Fluted liners Spin compensated liners
87
Plate Charges. What are they also known as?
- Miznay-Schardin Effect - Plate charge - EFP - Self forging fragment
88
Initiation methods of Explosives
``` Direct heat/flame Percussion and stabbing Electrical Shock Waves Electromagnetic Fields Laser Chemical Reaction ```

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