Formative 5 Revision Flashcards
define internal ballistics
the scientific study of the operating process within the gun from the moment the propellant is ignited until the projectile leaves the barrel
what are the goals of internal ballistics?
launch the projectile safely
launch the projectile with uniformity
achieve constant muzzle velocity
what is pioberts law?
the surface of a burning propellant receeds layer by layer in a direction normal to the surface
what factors effect the burning rate of propellant?
size
pressure
temperature
shape
what is the distribution of energy?
- Projectile 32%
- Residual heat of the gases 42%
- Recoil of the gun 0.2%
- Engraving of the driving band 2.8%
- Unburnt charges and hases 3%
- Heat lost to the gun 20%
what is the effect of an increase in charge weight?
Pressure increases
ABP moves back
Muzzle velocity increases
Regularity in fall of ahot improves
what is the definition of intermediate ballistics?
the study of the transition from internal to external ballistics that occurs in the vicinity of the muzzle
what are the two phases of the muzzle gas flow
- the precursor blast that precedes the projectile exit from the muzzle
- the main blast field that follows as high pressure propellant gases are ejected into the air
what is bottle shock and its two parts?
the projectile pushes air along the bore, so that when it exits the barrel it forms a shockwave.
- barrel shock
- mach disc
what are the types of muzzle flash?
- Pre-flash
- Primary flash
- Muzzle glow
- Intermediate flash
- Secondary flash
(P.P.M.I.S)
how do you minimise flash?
- Muzzle devices
- Type of propellant
- Propellant additives
name the 4 types of drag
- skin friction
- base drag
- forebody drag
- Excrescence drag
what are some methods to reduce drag?
- Base bleed
- Boatailing
what are the types of influence fuzes?
- Magnetic
- Acoustic
- Seismic
- Hydrostatic
what is an influence fuze?
a weapon subsystem that activates is warhead mechanism in the vincinity of a target and also keeps the warhead in a safe condition during all prior phases
what is a masking device? and its types
it obstructs the explosive train until arming is required, ensuring that if accidental prematire function of on part does occur it does not effect the whole train
what are the fuze principle requirements?
safety and reliability
a fuze is armed when?
all the safety components have been removed
what is the operation of a bore rodding pin?
a steel pin is not ejected until the projectile leaves the bore of the weapon - proving safety by interrupting tje arming mechanism
what are the forces acting on a fuze when firing?
- Set back
- Set forward
- Side slap
- Centrifugal
- Creep forward
what are the forces acting on a fuze in flight?
- Crosswind
- drift
what are the impact fuze actions?
- super quick
- non delay
- delay
- graze
what are three impact fuze catergories?
- point detonating
- base detonating
- point initiating base detonating
define a booster
a booster amplifies the detonation wave from a fuze to a larger charge such as a HE filling
what are the requirements of a fuze?
safety and reliability
what is the main design function of time fuzes?
designed to function a projectilr whilst in flight
what are the types of mechanisms in time fuzes?
- Thiel
- Tavaro
- Junghans
- Dixi
what is the doppler effect?
radio waves are reflected and picked up by the receiver within the fuze. reflected waves interfere with the radiated waves to give a beat known as the doppler effect. as the fuze gets closer to the target, the impulses increase to a defined peak value and the fuze functions.
