Explosive Ordnance Disposal Test

Classification of projectile fuzes

Method of operation

• Electrical

• Mechanical

Method of Functioning

• Impact

• Time

• Proximity

• Combination

Position in Store

• Nose

• Base/Tail

Impact Fuzes Description

• Detonates on impact

• Response can be divided into Super Quick (SQ, detonates instantly on contact), delay (detonates a fraction of a second after penetrating target)

Impact Fuzes Types

• Point Detonating (PD)

• Base Detonating (BD)

• Point initiating base detonating (PIBD)

Time Fuze Characteristics

• Detonates a projectile after a predetermined interval of flight

• Adjustable timings

• May incorporate self-destruct feature

Types of Time Fuze

• Powder train time fuze (PTTF)

• Mechanical Time(MT) fuze

• Electrical fuze

• Chemical Long Delay/NNC 82 fuze

Proximity fuzes / Variable Time (VT) fuzes

• Senses when target is close enough for weapon to be effective

  • Consists of a small radar set which sends signals and detects their reflections from nearby objects

• Presence of plastic nose cap

• May have time setting

• May have wrench slots

Combination Fuzes types

• Mechanical time and super-quick(MTSQ)

• Point detonating self-destruct (PDSD)

• Multi-option fuze artillery (MOFA)

Parts of an Aerial Bomb

• Bomb Casing

• Tail Unit

• Suspension Device

• Main Fillings

• Exploder System

Describe the Bomb Casing of an aerial bomb

• Primary Purpose: Holds the main filling and exploder system intact until detonation

• Secondary Purpose: Produces fragments to inflict casualties. 

  • Fragmentation Bombs have thicker casing.

• Thickness varies depending on the desired effects.

  • Incendiary bombs and blast bombs have thin casing to produce more blast and the incendiary can spread to a large area when detonated.

Describe the Tail Unit of an aerial bomb

• Maintains stability and accuracy during flight.

• conical backs allow more space for explosives

• Shapes and sizes of tail units vary with designs of bombs.

  • Box Fin

  • Conical Fin

  • Shrouded Fin

  • Retarded Fin (important)

Describe the Suspension Device of an aerial bomb

• Small bombs are suspended directly on aircraft.

• Larger bombs are spanned by one or more carrying bands.

• Lugs, bolts and bands are fragile and can be found on the UXO.

Describe the Main Fillings of an aerial bomb

• Incendiary

• Chemical Agents

• Pyrotechnics

• High Explosives

  • Cast Explosives

  • Powdered Explosives

Describe the Exploder System of an aerial bomb

• Provides a form of explosive energy to detonate the main filling

• Typical Parts include fuze, initiator and booster

Projectile Fuze Components

• Safety Feature

• Arming device

• Initiating device

• Explosive Elements

Types of Safety Features

• Holding Devices

• Masking Devices

List of Holding Devices

• Shear wire

• Striker spring and spring disc

• Striker cup

• Centrifugal balls, segments and arming sleeves

• Stirrup spring

• Ferrule

• Detent

List Masking Devices

• Non-Delay Arming or Masking Shutters

  • Sliding Shutter

  • Rotating Shutter

• Delay Arming Shutter

Two main types of arming devices

• Mechanical arming devices

• Electric arming devices

Types of Mechanical Arming Devices

• Springs

• Sliders

• Pin and Detent

• Rotary Devices

• Clockwork

• Vanes

• Stirrup & Ferrule

Describe spring mechanical arming device

• In the form of leaf spring, coil spring or power spring.

• Power springs are spiral spring used to drive a central drive shaft and related mechanisms in mechanical time fuzes

Describe slider mechanical arming device

Serves as barriers to prevent detonation of an explosive component.

Describe pin and detent mechanical arming device

Prevents accidental firing and will be released when arming conditions are met

Describe rotary devices mechanical arming device

• Centrifugal, spring or inertia driven

• Used to house an explosion element in the “OUT-OF-LINE” position.

Describe clockwork mechanical arming device

Consist of multiplication gear train, timing disc and escapement

Describe vanes mechanical arming device

Rotate during flight to move the arming mechanism of the fuze

Describe stirrup and ferrule mechanical arming device

requires setback and creep action to function

Types of Electric arming devices

• Trembler switch (Vibration)

• Mercury switch (Conductor)

• Reed switch (Magnet)

Initiating devices

• Striker, Firing pin and Anvil

• Hammer

• Inertia Pellet

• Pneumatic Chamber

• Electrical devices

Describe Electrical initiating devices

• Self-contained power sources

• Examples

  • piezoelectric transducer

  • electromagnetic generator

  • batteries (dry or wet cell/ thermal batteries)

  • capacitors used in fuzes

  • RC timing ciruit

List Explosive Elements (Fuze component)

• Primer

• Detonator

• Leads

• Booster

Describe primer explosive element

Converts kinetic energy to heat/explosion. Eg. firing pin hits a primer cap

Describe detonator explosive element

• Initiates a detonation with a shock wave

  • can be initiated by a primer, or sufficient heat, mechanical or electrical energy

Describe leads explosive element

directs detonation wave

Describe Booster explosive element

• final component in an explosive train before the bursting charge

• initiated by one or multiple leads or a detonator

Components of a missile

• Guidance system

• Warhead

• Propulsion System

• Control Section

• Airframe

Describe guidance system

• It gathers information on the relative positions and/or the relative velocity of the missile and its target and computes a suitable course to bring the missile into lethal range of the target

• **NOT THE FUZE, only guides the missile. Fuze is normally found at the warhead

Types of guidance systems

• Passive

• Semi-active homing

• Active homing

• Command

• Radio Command

• Wire

Describe passive guidance system

• A sensor uses natural energy, which is emitted or reflected from the target, to track the target

• This energy can either be infrared or other emissions

Describe semi-active homing guidance system

• Beam sent from radar lamp on aircraft.

• This beam will be reflected by the target and received by the missile with a radar receiver.

• The missiles homes in on target-reflected radiation

Describe active homing guidance system

• The missiles has its own guidance radar (transmitter and receiver) to detect the target.

• detects the energy reflected by the target

• The homing head continues to illuminate and track the target until impact

Describe command guidance system

• Ground-based radars track missile position and target position, and control missile flight towards target

Describe radio command guidance system

The system can be controlled by personnel on ground or pilot in the cockpit by means of radio link to direct the missile to the target.

Describe Wire guidance system

• Eye tracks the relative direction of target and missile and the brain guides the missile onto the target.

• The command link is very often a wire spooled out by the flying missile.

• short range, anti-tank

• Resistance to ECMs but the highly skilled operator needs continuous training

Parts of a warhead system

• Fuze

• Initator

• Warhead

Types of missile warhead fuzes

• Active fuzing

• Passive fuzing

• Contact fuzing

*Fuzing may incorporate a self-destruct mechanism

Describe the initiator of a warhead system

• A link between the fuze and the warhead

• A safety break before launch

• An arming link before launch

• A self-destruct device

Desirable characteristics of a missile warhead

The warhead is the business end of the missile. Some desirable characteristics are

• efficiency because of the cost and complexity of the system

• the ability to concentrate the destructive effects at the target

• durability

• reliability

Types of warhead

• Blast

• Fragmentation

• Continuous Rod (CR)

• Single Shaped Charge

• Multiple Shaped Charge

• Medium Capacity

• Squash Head

• Sub-projectile

• Nuclear/Chemical

Two types of missile propulsion systems

• Rocket motors

• Air Breathing (jet) engine

Rocket motors missile propulsion

• Fuel and oxidizer are contained within the missile and can be used outside the atmosphere

• Two types: Solid Propellant & Liquid propellant

Solid propellant rocket propulsion

• Heavy motors which are readily transportable and can survive field conditions.

• Fairly reliable, difficult to control performance

Liquid Propellant rocket propulsion

• The fuel and the oxidizer are usually tanked separately.

• propellant flow rates can be controlled on demand to vary thrust.

• All liquids used are dangerous either in liquid or vapor form

Types of Air Breathing engines missile propulsion

• Pulse jet → uses resonant combustion, low specific impulse. One way valves lets air in and forces combusted gases out

• Turbojet

• Ramjet → uses forward motion to produce constant thrust, needs rocket assistance to bring it up to speed

Control Section of missiles

• the guidance section supplies information to move control surfaces, changing the missile’s flight path

• stabilizes the missile during flight

• Two main kinds of control surface: Canard wings and fins / Vectored Thrust

Types of cluster munitions

• Anti-personnel

• Anti-tank 

• Anti-runway 

• Mine-laying

• Anti-electrical

• Incendiary 

• Chemical 

• Leaflets

Describe High Explosive Squash Head (HESH)

• HESH rounds are thin metal shells filled with plastic explsoives and a delayed-action base fuze.

• On impact, the plastic explosive is ‘squashed’ against the target surface, forming a disc or ‘pat’ of explosive

• The explosion milliseconds later creates a shock wave that is transmitted through the material, because of its large surface area and direct contact with the target.

Factors affecting HESH design

• HE filling must be in close contact with the armor plate

• Shock wave travels towards the plate (needs to be detonated with a base fuze)

• Thin shell well to crush open and spread explosive out on impact

• HE filling must be sufficiently insensitive to withstand impact

• Inert pad at nose to absorb impact

Advantages of HESH

• Unaffected by the angle of attack

• Useful against most targets eg. reinforced concrete, bunkers or anti-personnel effect

• Physiological effect - at least stun the crew with 7lbs of HE from a 120mm HESH tank shell

Disadvantages of HESH

• low strike velocity, limited at 700mps

• defeated by spaced armor on target

• Performance falls if charge is disrupted in any way

Describe General Purpose aerial bomb

• Usually with a pointed nose and have a charge/weight ratio of 33-60%.

• Weight ranges from 20-1900lbs.

• Causes damage through blast, fragmentation & earth shock

• Used for general bombardment

Describe Deep Penetration aerial bomb

• Creates damage through earth shock

• Medium capacity and have a solid nose

• Weight ranges from 12000-22000lbs

• Charge weight ratio of 45% or less

• Tail delay fuze

Identification features of rockets

• Long and cylindrical shape

• Presence of fins at the rear (unfolds upon launched)

• Presence of venturi or exhaust ports at the rear

• Spin stabilized rockets have slanted venturi and may not come with fins

Describe Kinetic energy projectiles

• a solid projectile or shot is carefully shaped to provide penetrative performance and concentrate as much energy as possible over a small target area

  • aka. “SHOT”

• Lacks a fuze, but has a tracer to track its progress

Advantages of kinetic energy projectiles

• Increased chance of a hit due to a flat, fast trajectory

• Quicker engagement and response time

Disadvantages of kinetic energy projectiles

• Requires large and heavy guns

• Requires large quantities of propellant

• High maintenance of barrel due to wear and tear

• Ineffective against certain armour

Types of Kinetic Energy Ammunition

• Orthodox Steel Armor Piercing Shot

  • Armor Piercing (AP)

  • Armor Piercing Capped (APC)

  • Armor Piercing Capped Ballistic Cap (APCBC)

• Armor Piercing Composite Rigid (APCR)

• Armor Piercing Composite Non-Rigid (APCNR)

• Armor Piercing Discarding Sabot (APDS)

• Armor Piercing Fin Stabilized Discarding Sabot (APFSDS) → Made of Depleted Uranium, fins for stability

18 EOD Hazards

1. High explosive (HE)

2. Fragmentation (FRAG)

3. Electro-magnetic radiation (EMR)

4. Static electricity (STATIC)

5. Chemical

6. Ejection

7. Magnetic

8. Acoustic

9. Proximity (VT)

10. Wait time

11. Movement

12. Cocked striker

13. Fire

14. White phosphorus (WP)

15. Piezo-electric crystal (LUCKY)

16. Jet

17. Booby trap

18. Clockwork

Degrees of evacuation

• Complete evacuation

• Partial evacuation

Describe complete evacuation

• Enforced due to Blast effect & fragments from the detonating bomb

• No movement is allowed, except EOD operators

• All personnel & transportable equipment are evacuated

Describe Partial evacuation

• Enforced mainly due to fragments from the detonating bomb

• All accommodation, vehicles & fragile stores not adequately shielded must be evacuated

• Rooms on remote side of building may be occupied but access must be by means of shielded approaches

• Pedestrians & vehicular traffic will only be permitted with adequate shielding

• All roads leading into this area must be cordoned off and traffic redirected

Bulk disposal of HE ordnance

• Drum method of burning

• Trench method of burning

High order Detonation

• The least desired result of Special Demolition Technique.

• Ordnance completely detonates at the maximum velocity of detonation

• Due to the ordnance functioning as designed or the failure of the SDT

Low Order detonation

• Insufficient energy to propagate the detonation wave, causing incomplete/partial detonation.

• Desired as it prevents the ordnance from functioning as designed

• Remaining explosive either scattered or confined within the casing

Purpose of protective works

• Used to prevent damage to structure or services:

  • Should a bomb inadvertently explode

  • If a bomb needs to be disposed off in situation

• Used to reduce the extent of evacuation

Factors determining type of protective works/Damage control plan guidelines

• Type & weight of UXO

• Disposition of UXO

• Vicinity where UXO landed and found

• Buried/unburied

• Conditions for ground where UXO landed

• Tactical situation

• Other Considerations

  • High rise buildings

  • Low lying buildings

  • Underground services/structures

  • Importance of installations/equipment

Types of protective works

• trenching

• venting

• Sandbag abutment (buttressing)

• Protective wall

• Protective surround

• Protective mound

• Post-hole method

• Disposal pit

• Sandbag surround with overhead cover

Describe Post-hole method

• Earth auger used to bore a hole to required depth, not less than 1m

• Ordnance lowered into hole after placing charges

• Sandbags are stacked on top of the ordnance in an interlocking manner

• Ordnance less than 160mm mostly disposed of during this method (Safe to Move)

• For ordnance:

  • Up to 81mm - 3 layers

  • Up to 120mm - 5 layers

  • Up to 160mm - 7 layers

Describe Disposal pit

• Used for disposing ordnance greater than 160mm (Safe to Move)

• Aerial bombs normally disposed off using this method

• Pit depth minimally 2m, or equal to pit length

• Pit width 1.5m

• Pit supported by stakes

• Structure above pit: sandbags at pit sides, 4×4 planks spanning pit, zinc sheets on planks, 8 layers of sandbags

Purpose of Special Demolition techniques

• To break the explosive train

• To counter anti-handling devices, which rule out RSPs

• quickly gain access to main fillings

Things to take note of before applying SDT

• Type and condition of fuze

• Type and size of ordnance

• Proximity of Buildings and Utilities

• Time

Factors affecting the performance of SDT

• Type of explosives used for the attack

• Material used for the attack → affects slug formation and performance

• Stand-off applied → the distance between the shaped charge and the ordnance

• Explosive fillings of ordnance being attacked

• Thickness and material of ordnance being attacked

Results of SDT

• High Order Detonation

• Low order Detonation

• Deflagration

List SDT methods

• Round tom method

• X1E1 Point focal charge method

• Ballistic Disk

• Linear Shaped Charge

• Thermite incendiary grenades

• Detonating Cord Method

Describe the Round Tom method

• Charges placed in the groove at the base of the ordnance, to shear the base plate off through overpressure and exposing explosive fillings

• Quantity of explosive depends on size of ordnance

X1E1 Point Focal Charge Method

• Uses the Munroe effect to produce a molten slug, which penetrate the ordnance and splits the casing by causing low order detonation

• 6-8”(150-200mm) standoff optimal. 

• Placed perpendicular to the ordnance

• Ordnance casing should be between 0.2-0.75” thick (thin cased ordnance).

• X1E1 container ⅔ filled with plastic explosives. When filling X1E1, ensure no air gaps in the explosive and that it is compact with the copper disk

Ballistic Disk

• A copper Misznay Schardin plate is attached to one end of an aluminum tube.

• It penetrates the UXO casing with a self-forging slug

• Optimum standoff 400-450mm, placed perpendicular to ordnance

• Ensure no air gaps during charge preparation

Entry hole characteristics for small bombs <500lbs

• Clean cut entry holes

• Approximately two inches greater than caliber of bomb

Entry hole characteristics for large bombs >500lbs

• Splash crater is formed

• Debris is scattered around and fills the bottom of the crater, thus obstructing the true entry hole

Category A

Direct impact to war effort and human lives

Category B

Indirect impact to war effort or incidents which have consequences to human lives

Category C

Little impact by which UXO cannot be left unattended indefinitely

Category D

No impact to habitations or communication. May be dealt with when convenient

Phases of Area Clearance

1. Report and receipt of request

2. Area clearance reconnaissance

3. Planning and organization

4. Clearance

5. Final Disposal and recording

Considerations for area clearance reconnaissance

• Future use of land

• Nature of UXO discovered

• Density of Ordnance (per 10000sqm)

  • Very light - 1 to 2 ordnance

  • Light - 3 to 4 ordnance

  • Normal - 5 to 8 ordnance

  • Dense - 9 to 12 ordnance

  • Very Dense - 13 and above ordnance

RSP options

• Fuze extraction method (Rocket wrench)

• Fuze Disruption method (De-armer)

Purpose of EOR

• Determine whether an UXO exists

• Know the exact location of the UXO, or the estimated location and depth in the case of a buried UXO

• The probable size and type of the UXO

• The likely damages if the UXO explodes

• The most appropriate follow up actions to be taken

• If it is not an UXO, then what is it?

Factors affecting the path of bomb

• Striking velocity

• Mass

• Stability

• Properties of soil

• Surface obstacles

• Underground obstacles

• Assisted Propulsion

Striking velocity affecting path of bomb

• depends on the height at which bomb was dropped, its ballistic properties and whether or not it was powered.

• Air resistance prevents them from acquiring the full speed attainable with gravity

Mass affecting path of bomb

Penetration is approximately proportional to the mass of the bomb

Stability affecting path of bomb

affected by:

• shape

• length diameter ratio

• position of the center of gravity

• the speed of which it was travelling

• type of soil

• how straight the flight path was at entry