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AT 2023 notes > LO6 - Fuzes > Flashcards

LO6 - Fuzes Flashcards

1
Q

Definition of a fuze

A
  • A fuze is a device designed to function an item of ammunition under pre-determined circumstances.
  • A fuze is a device designed to initiate an explosive munition at the correct time or place.
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2
Q

REMEMBER THIS QUESTION

Abbreviations by position of fuze?

A

PD - Point Detonating
BD - Base Detonating
PIBD - Point Initiating Base Detonating

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3
Q

Abbreviations by function of fuze?

T, CT, MT, VT, CVT, SQ, DEL, MTSQ, TSQ, PDSQ, MO, ET

A

T - Time
CT - Combustion Time (May also be PTTF)
MT - Mechanical Time
VT - Variable Time
CVT - Controlled Variable Time
SQ - Super Quick
DEL - Delay
MTSQ - Mechanical Time Super Quick
TSQ - Time Super Quick
PDSQ - Point Detonating Super Quick
MO - Multi Option
ET - Electronic Time

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4
Q

REMEMBER THIS QUESTION

General requirements and other requirements of fuzes

A

General
* SAFETY
 For storage and transport
 Against premature functioning
* RELIABILITY
 To high order when required
Other requirements
* Optional delay setting
* Easy time adjustment / setting
* Minimum preparation for use
* Multi role to minimise refuzing
* Standard weight
* Must fit standard cavity size
 2 inch Artillery
 1.5 inch Mortar

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5
Q

Fuzes are classified according to what three categories?

A
  • Filling
  • Position
  • Function
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6
Q

Fuzes classified by function have what three types?

A
  • Time
  • Impact
  • Proximity
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7
Q

Impact Fuzes are divided into which three categories?

A
  • Super Quick(SQ),
  • Graze
  • Delay
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8
Q

Definition of arming

A

The process of arming is the unlocking of the devices at the correct time in the correct sequence.

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9
Q

Forces available

A
  • Set-back
  • Centrifugal Force
  • Spin Decay
  • Creep Forward
  • Set Forward
  • Air or Gas Pressure
  • Stored Energy

ACSSCSS

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10
Q

Explanation of forces available

A
  • Set-back - This arises from the reaction of the mechanism to the acceleration forces applied in the gun on firing.
  • Centrifugal Force - Any component whose centre of gravity is off the
    axis of the fuze tends to be thrown outwards as a tends to be thrown outwards as a result of centrifugal force generated by the angular velocity imparted to the projectiles.
  • Spin Decay
     In the same way that a projectile loses linear velocity, it loses angular velocity.
     This decrease in angular velocity can be used to trigger a self–destruction device
  • Creep Forward
     When the acceleration phase ends, components which have been locked tend to ease forward on their seatings.
     Springs which have been compressed begin to re- assert themselves.
     This gradual unlocking process permits spin forces to act on components susceptible to them.
  • Set Forward - The relative forward movement of components when a fuze decelerates on impact.
  • Air or Gas Pressure
     Air or Gas pressure is sometimes used to drive a turbine to generate power for electrically operated fuzes.
     Used as an alternative arming method for non spun projectiles such as mortars.
  • Stored Energy - is usually a spring (mechanical) used to operate clockwork devices or to move shutters.
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11
Q

Common Methods Of Operation of fuses

A
  • A common method of operation is the Four – Stage one/type of:
     Unlocking a component by set–back forces.back forces.
     Easing it on its seating during creep forward.
     Swinging it to an armed position by the application of centrifugal force.
     Initiation of the explosive train by set forward on impact.
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12
Q

Principle requirements of fuze

A
  • The principal requirements of fuzes are safety and reliability.
  • All fuzes embody mechanical devices which ensure the Fuze:
     Functions at the desired moment
     Remains safe in handling, before and during loading
     Remains bore and muzzle safety immediately after firing
     Arms after leaving the muzzle
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13
Q

Broad categories of fuze systems

A
  • Mechanical and Electro/Mechanical –Out of line
  • Electronic/Mechanical –Out of line.
  • Electronic –In line
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14
Q

Princinple requirements definitions

A
  • Arming
  • Material compatibility
  • Design safety
  • User inspection
  • Explosive train
  • Mechanical Lock
  • Delay arming
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15
Q

Different mechanism in a fuze.

A
  • Holding Devices - A holding device locks other components in a safe position until arming is required; to unlock them when arming is required; and possibly to relock them in the armed position.
  • Locking Devices
  • Safety Devices
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16
Q

Define Firing Devices. How it is achieved and types

A
  • A firing device is the component which provides the stimuli to initiate the explosive train.
  • It may be achieved by either electrical or mechanical.
  • Electrical Firing:
     Conducting Cap (CC).
     Bridge Wire (BW).
     Exploding Bridge Wire type (EBW).
  • Mechanical firing is invariably achieved in modern fuzes by stabbing a detonator with a firing pin.
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17
Q

Other Fuze Components

A
  • Pellets.
  • Detonators.
  • Magazine or booster.
  • Channel.
  • Protective Cover/Cap:
     Striker Cover.
     Safety Cap.
  • Delay Systems.
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18
Q

Advantages of Electronics

A
  • Lowers costs due to multi role function.
  • Versatility in arming.
  • Mechanical preparation or initiation.
19
Q

There are two type of masking devices. What are they?

A
  • Non Delay Arming or Masking Shutters and Slides.
  • Delayed Arming Shutter
20
Q

Time fuzes are set for time before loading by what devices?

A
  • Rotation
  • Use of a moving portion of fuze with fuze key
  • Fuze setter
  • Fuze setting machine
21
Q

Time fuzes can be divided into three types

A
  • Combustion (T) – Powder Train Time Fuze (PTTF)
  • Mechanical (MT)
  • Electronic (ET)
22
Q

3 different types of MT fuzes

A
  • Thiel - British MT Fuzes
     A series of wheels and pinions controls the escape of from a main spring which is wound up during manufacture
  • Junghans - American MT Fuzes
    This mechanism is actuated by spring assisted by centrifugal weights
  • Dixi - Swiss Fuze
     This mechanism is driven by centrifugal force acting on driving balls
23
Q

What is the main design function of the time fuzes?

A

Time Fuzes are designed to function after a predetermined time whilst in flight

24
Q

Definition of proximity fuze

A

Proximity fuzes are automatic time fuzes, with or without PD element, that are designed to function a projectile at the optimum lethal distance from the target, provided that in the case of aircraft targets, the trajectory passes sufficiently close.

25
Q

Proximity Fuzes are divided into two groups

A

 Variable Time (VT) Timer section arms the fuze electronically after firing. No setting for optimum height.
 Controlled Variable Time (CVT) Can be set to activate the Prox function after a set time.

26
Q

Design consideration of PROX fuze

A
  • Rugged.
  • Able to function in all conditions.
  • Light weight.
  • Economical.
  • Able to fit existing projectiles.
  • Sensitive and rapid in operation.
  • Not easily jammed.
  • Not subject to false operation.
  • Safe to handle.
  • Have good storage characteristics.
27
Q

Basic sections of Prox fuze

A
  • The Nose
  • The Steel Base
  • The Sleeve
28
Q

Basic functioning of prox fuze

A
  • On firing, setback breaks the ampoule or electrolyte which floods the energiser.
  • Clock starts (CVT only) and the shutter starts to rotate.
  • An electric igniter is short circuited until 3 –5 5 seconds after firing.
  • Transmitter radiates radio waves.
  • Nearing the target… Doppler effect activatesDoppler effect activates
  • FUZE DETONATES.
29
Q

Define Doppler effect.

A
  • Radio waves are emitted by the fuze, some of the waves are reflected and picked up by the receiver.
  • The time taken to return affects the Reflected waves, which interfere with the radiated waves to give a beat known as the Doppler effect.
  • As the fuze gets closer to the set target distance the impulses increase to a defined peak value and the fuze functions.
30
Q

General safety features of prox fuze

A
  • Battery is inert until ampoule is broken.
  • Clockwork mechanism prevents signal transmission or functioning until pre-set time.
  • Shutter or S & A mechanism keeps explosive train out of line.
  • Electric components can be short circuited until safe to arm has operated as intended.
31
Q

Why are proximity fuzes are commonly stored
nose down?

A

The battery ampoule activates on setback (rearward), so impact nose-down is less likely to down is less likely to activate the battery.

32
Q

How are electronic fuze functioned?

A
  • Electronic fuzes are functioned by a current passing through electric leads from some sort of battery.
  • Power Sources:
     Battery
     Turbine generated
     Precharged
     Electostatic
33
Q

What results can be expected from a Proximity Fuze when dropped from 1 m or more?

A

Care should be taken not to strike or drop fuzes or fuzed rounds because a drop in excess of 1m may result in a UXO when fired.

34
Q

Define MOFA.

A

A fuze designed to provide a selectable function capability and can include a Proximity function option.
*Proximity
*Superquick
*Delay
*Near Surface Burst

35
Q

Impact fuze actions

A
  • Superquick (SQ)
  • Non Delay
  • Graze
  • Delay
36
Q

Explain SQ fuzes

A
  • The mechanism of these fuzes consists of:
     A needle supported by a thin metal disc or,A needle supported by a thin metal disc or,
     A hammer/striker supported on a shear wire or A hammer/striker supported on a shear wire or coiled spring.
     Exposed to a direct blow on impact with the target.
  • Sensitivity depends on the strength of the disc, shear wire or coiled spring.
37
Q

Explain Non delay fuzes

A
  • These fuzes differ from the SQ fuzes mainly in being less sensitive.
  • The mechanism usually consists of a steel hammer / striker supported on a stout shear pin.
38
Q

Define graze element fuzes

A
  • The interior mechanism of graze action fuzes is so arranged that when the projectile is checked in flight or receives an appreciable deceleration.
  • A moveable part, usually called the graze,inertia pellet or plunger moves forward to carry the detonator on to the needle (or vice versa).
  • A creep spring keeps the two apart until this deceleration is experienced.
  • As the movement of the plunger or weighted needle gives rise to an ‘air gap’ the fuze detonator is of the flash type.
  • Graze fuzes have a small inherent delay.
39
Q

Define delay fuzes

A
  • These fuzes usually have a masking shutter, interrupter or pyrotechnic composition in-built into the detonating train between the initiator and the fuze magazine so there is a slight delay between the actuation of the initiator and the firing of the magazine.
  • This may be achieved by channelling the flash from the initiator around a longer route or slowing it by having to wait for the pyrotechnic composition to burn through before it reaches the next component.
40
Q

Types of impact fuzes

A
  • Point Detonating Fuzes (PD)
  • Point Initiating Base Detonating Fuzes (PIBD).
  • Base Detonating Fuzes (BD)
41
Q

Other functions that can be included in impact fuzes.

A
  • Time and impact
  • Proximity and impact
  • Self- destruct
42
Q

Prox fuze dropped

A

Unpackaged drop –1.5m (e.g. M732A2)1.5m
Packaged drop - 2.0m
Safe lift height –12m

43
Q

PROX fuze storage.

A
  • Protected from
    Dampness
    Sunlight
    Heat
    Drop/ Strike

AT 2023 notes (9 decks)

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