Fuzes Flashcards
Forces available to operate a fuse mechanism? 7
Set back Creep forward Centrifugal force Spin decay Set forward Air or gas pressure Stored energy
What is set forward?
The relative forward movement of components when a fuze decelerates on impact
What is set back?
The physical backward movement or anchoring of components compresses any springs which are placed axially in the fuze
What is creep forward?
When acceleration phase ends, components which have been locked tend to ease forward on their seatings.
Springs which have been compressed begin to reassert themselves.
This gradual unlocking process permits spin forces to act on components susceptible to them
What is centrifugal force?
Any component whose centre of gravity is off the axis of the fuze tends to be thrown outwards as a result of centrifugal force generated by the angular velocity imparted to the projectiles.
What is spin decay?
In the same way that a projectile loses liner velocity, it loses angular velocity.
This decreases in angular velocity can be used to trigger a self destruction device
What is air or gas pressure?
Air or gas pressure is sometimes used to drive a turbine to generate power for electricity operated fuzes.
Used in non spun ie mortars
What is stored energy?
Stored energy is usually a spring used to operate clockwork devices or to move shutters.
Chemical energy in an energiser for example, may be used to generate electrical power or gas under pressure
Proximity fuze definition?
Proximity fuzes are automatic time fuzes, with or with out 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
Design considerations? 10
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 a good storage characteristics
3 basic sections of prox fuze?
The nose
The steel base
The sleeve
What is the Doppler effect?
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.
4 power sources for electric fuzes?
Battery
Turbine generated
Precharged
Electostatic
Fuze definition?
Fuze is a device designed to function an item of ammunition under predetermined circumstances
2 general requirements of a fuze?
Safety
Reliability
Fuzes are classified according to what 3 categories?
Filling
Position
Function
Fuzes classified by function have what three types?
Time
Impact
Proximity
Impact fuzes are divided into which 3 categories?
SQ
Graze
Delay
4 impact fuze actions?
SQ
Non delay
Graze
Delay
What are the 3 types of time fuze?
Mechanical
Combustion
Electronic
What is the main design function of time fuzes?
Time fuzes are designed to function after a predetermined time whilst in flight
There are 3 types of MT fuze, what are they?
Thiel - British
Junghans - American
Dixi - Swiss
There are the types of masking devices?
Shutters
Delay or non delay shutter ??????????
3 advantages of electronics in fuzes?
Lower cost
Versatility in arming
Mechanical preparation or initiation
Safety features of mechanical fuzes?
Safety arrangements can be check before and after assembly
Can not be assembled in unsafe conditions
