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Ballistics > Ballistics > Flashcards

Ballistics Flashcards

1
Q

What is internal ballistics?

A

The scientific study of the operating process within the gun from the moment that the propellant is ignited until the projectile leaves the barrel

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2
Q

What are the 4 phases of ballistics?

A

Interior
Intermediate
Exterior
Terminal

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3
Q

What are the 3 objectives of internal ballistics?

A

Launch the projectile safety
Consistent performance between shots
Achieve the highest possible muzzle velocity

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4
Q

What is muzzle press?

A

Peak over pressure at the muzzle upon breakage of the projectile bore seal

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5
Q

What are the 4 phases of internal ballistics?

A

Charge ignition
Combustion prior to projectile motion
Combustion up to the all burnt point
Gas flow and projectile motion after all burnt point to muzzle

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6
Q

Explain charge initiation?

A
  • the propellant is usually initiated by either a percussion or electrical primer
  • the primer releases hot gases and particles into the charge
  • the hot gas flow causes the propellants surface temperature to increase
  • this hot gas flow is like a blast wave through the chamber
  • the gas flow also increases the pressure within the chamber
  • the high temperature and pressure causes the propellant to initiate
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7
Q

The primer needs to ensure consistent and effective charge initiation or otherwise what will happen?

A

Irregular initiation will lead to misfires and variations between shots

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8
Q

What is primer leakage?

A

Pressure loss due to the primer in the cartridge case not providing obturation

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9
Q

The primer must what 2 things?

A

Provide obturation to avoid pressure loss

Withstand the initiation forces (firing pin impact), pierced primer

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10
Q

What does piobert’s law describe?

A

The surface of deflagrating propellants will recede layer by layer in a direction normal to the surface

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11
Q

Explain burning rate?

A

Is the rate at which a granule reduces in size as the burning of that granule occurs on all sides

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12
Q

What is pressure index?

A

Coefficient which relates to changes in burning rate to changes in pressure

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13
Q

What is burning characteristics of propellant composition?

A

Burning rate
Pressure index
Force constant
Co-volume

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14
Q

What is burning characteristics of propellant granule?

A

The ballistic size

The form function

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15
Q

What is co-volume?

A

The volume occupied by the molecules of a kg of propellant in a gaseous state

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16
Q

What is force constant?

A

A measure of the pressure which a unit mass of propellant produces in a fixed volume

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17
Q

Force constant = what?

A

Force constant = maximum pressure X effective volume of closed-vessel / mass of propellant

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18
Q

What is ballistic size?

A

Is the shortest distance between any two points on the surface of a propellant granule

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19
Q

What is form function?

A

How the surface area of a propellant grain of a particular shape changes during combustion

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20
Q

What type of propellant will effect the internal ballistic phase?

A

Single vs double

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21
Q

7 Characteristics of propellant?

A 
Burning rate
Pressure index
Co volume 
Force constant 
Ballistic size
Form function 
Single vs double
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22
Q

Single based propellant has a what burn which results in a what pressure for a what period?

A

Single
Higher
Short

23
Q

Double based’s what burn results in what pressures for a what duration?

A

Double
Lower
Longer

24
Q

(11)what is the firing sequence?

A
  • Initiation of the primer
  • Propellant combustion
  • Increase in pressure & temp thereby increasing the burn rate
  • Shot start
  • Acceleration of the projectile
  • Peak pressure
  • increase in volume
  • all burn point
  • acceleration increases
  • pressure is 1/16 of peak pressure when the projectile is at the muzzle
  • entire process from initiation to muzzle exit less then 15 milliseconds
25
Q

Areas of Distribution of energy when the gun is fired? (6)

A 
Projectile-32%
Residual heat of the gases-42%
Recoil of the gun-0.2%
Engraving the driving band/barrel friction-2.8%
Unburnt charges and gases-3%
Heat lose to the gun-20%
26
Q

What are the effects of variations? (7)

A 
Charge weight
Propellant size
Chamber capacity 
Ignition temperature 
Shot start
Bore area
Multiple variations
27
Q

What are the four ballistic abnormalities?

A

Occasion to occasion effect
The warmer (cold gun) effect
Order of fire
Ballistic hump

28
Q

How can the round to round regularity of muzzle velocity be improved?

A

If burning finishes while the shell is still well back in the bore

29
Q

What is the effect of using a multi tubular propellant on internal ballistics?

A

The peak pressure is reduced but the projectile still gets good energy levels

30
Q

What is the effect on internal ballistics of using a projectile of normal weight, but shorter and of larger diameter than normal?

A

The same muzzle velocity is achieved with a pressure which is everywhere less than with the standard shot

31
Q

Definition of intermediate ballistics?

A

The study of the transition from internal to external ballistics that occurs in the vicinity of the muzzle

32
Q

Two phases of gas flow field?

A

The precursor blast field that proceeds the projectile exit from the muzzle

The main blast field that follows as high pressure propellant gases are ejected into the air

33
Q

Two parts of bottle shock?

A

Barrel shock-sides

Mach disc-front

34
Q

2 main blast field effects?

A

As the propellant is travelling quicker than the projectile, it will catch up to the projectile and possibly impart a small amount of acceleration

The forces could also cause the projectile to yaw as the shock waves catch up with the projectile

35
Q

5 Types of flash?

A 
Pre flash
Primary flash
Muzzle glow
Intermediate flash
Secondary flash
36
Q

3 Flash reduction methods?

A

Muzzle devices (flash suppressors)
Type of propellant
Propellant additives

37
Q

3 reasons for muzzle devices?

A

Reduce recoil
Suppress flash
Decrease report - silencer

38
Q

2 reasons for flash suppression?

A

Reduce signature

Reduces possibility of temp blindness

39
Q

3 types of muzzle suppressors?

A

Conical tube
Slotted tube
Bar type

40
Q

What does a flash suppressor do?

A

Breaks up the bottle to remove the heat from the secondary flash

41
Q

2 flash reduction methods?

A

Choice of propellant-Triple based propellant

Propellant additives-potassium and sodium salts inhibit the formation and burning of hydrogen gases however do create more smoke

Muzzle devices

42
Q

Two main muzzle blast sources?

A

Blast shock wave

Flash blast

43
Q

3 types of silencers?

A

Blast absorption
Blast dissipation
Blast containment and controlled release

44
Q

What is recoil?

A

Recoil is the rearward motion of the gun in reaction to the forward motion imparted by the projectile and propellant gases

45
Q

2 ways to counter recoil?

A

Braking system
Muzzle breaks - can do 50% but causes gunner damage
- normally 25%

46
Q

How many projectile lengths in intermediate?

A

7

47
Q

How do most flash suppression devices reduce flash?

A

Break up the barrel shock

Mach disc

48
Q

4 properties of the projectile?

A

Mass
Calibre
Nose shape
Spin

49
Q

3 properties of the atmosphere?

A

Air density
Temperature
Pressure

50
Q

What is trajectory?

A

The trajectory is the path taken by the centre of gravity of the projectile

51
Q

Air resistance- 4 drag forces?

A

Skin friction
Pressure drag
Forebody drag
Excrescence

52
Q

The atmosphere up to an altitude of 20km is basically composed of?

A

78% nitrogen
21% oxygen
1% comprising of water, carbon dioxide, hydrogen and other gases

53
Q

Viscosity and what 3 all vary with altitude?

A

Pressure
Temperature
Density

Ballistics (1 decks)

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