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01. AT 2025 > SA05 - Ballistics > Flashcards

SA05 - Ballistics Flashcards

1
Q

Internal Ballstics

What is ballistics?

A

The scientific study of the motion of projectiles

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2
Q

Internal Ballistics

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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3
Q

Internal Ballistics

Objectives of Internal Ballistics

A
  • Launch the Projectile safely
  • Consistent performance between shots
  • Achieve the highest possible muzzle velocity
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4
Q

Internal Ballistics

Definition of All burnt point

A

The point where all the propellant has been consumed.

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5
Q

Internal Ballistics

Definition of Peak Pressure (MPa)

A

The point where the Max pressure is reached.

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6
Q

Internal Ballistics

Definition of shot start

A

The point where the projectile begins to move.

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7
Q

Internal Ballistics

Definition of Shot Exit

A

The point at which the projectile exits the muzzle.

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8
Q

Internal Ballistics

Definition of Ignition Temp (degree C)

A

Temperature required to ignite propellant.

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9
Q

Internal Ballistics

Definition of Explosion heat (Qex)

A

Amount of heat liberated in the combustion of 1kg of propellant.

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10
Q

Internal Ballistics

Definition of Flame Temp (degree C)

A

Peak chamber temperature upon combustion of propellant.

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11
Q

Internal Ballistics

Definition of Chamber press (MPa)

A

Pressure at the case mouth

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12
Q

Internal Ballistics

Definition of Specific gas vol (L/KG)

A

Amount of gas produced from 1kg of propellant.

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13
Q

Internal Ballistics

Definition of muzzle press

A

Peak overpressure at the muzzle upon breakage of the projectile-bore seal.

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14
Q

Internal Ballistics

Definition of solid residue (%)

A

w/w% of solid matter remaining after combustion.

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15
Q

Internal Ballistics

Definition of muzzle velocity

A

Projectile speed at exit from the barrel.

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16
Q

Internal Ballistics

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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17
Q

Internal Ballistics

Burning characteristics of propellant

A
  • Propellant composition
  • Propellant Granule
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18
Q

Internal Ballistics

characteristics of propellant composition

A
  • Burning rate
  • Pressure index
  • Co-volume
  • Force Constant
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19
Q

Internal Ballistics

characteristics of propellant granule

A
  • The ballistic size
  • The form function
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20
Q

Internal Ballistics

Single vs double based propellant

A
  • Single based propellant has a single burn which results in a higher pressure for a short period.
  • Double based double burn results in lower pressures for a longer duration.
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21
Q

Internal Ballistics

Firing sequence

A
  • Initiation of the primer.
  • Propellant combustion.
  • Increase in Pressure and Temperature thereby Increasing the Burn Rate.
  • Shot Start.
  • Acceleration of the projectile.
  • Peak pressure:
    - 1/10 of the Barrel length.
  • Increase in volume:
  • Decrease in pressure.
  • All burnt point.
  • Acceleration increases slightly.
  • Pressure is 1/6 of peak pressure when the projectile is at the muzzle.
  • Entire process from initiation to muzzle exit takes less than 15 milliseconds.
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22
Q

Internal Ballistics - REMEMBER THIS QUESTION

When is peak pressure reached?

A

The peak pressure is reached once the projectile has travelled approximately one tenth (1/10) of a full length barrel.

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23
Q

Internal Ballistics

Definition of Silver point

A

The point in time where the holes in a multi-perforated/tubular grain of propellant expand and meet each other, creating independent slivers of unburnt propellant. At this point the grain becomes degressive, but is overall considered a progressive burning type.

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24
Q

Internal Ballistics - REMEMBER THIS QUESTION

What is the pressure at the muzzle?

A

1/6 of peak pressure when the projectile is at the muzzle

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25
# Internal Ballistics - REMEMBER THIS QUESTION Explain the distribution of energy from propellant burning
* Projectile (translational & rotational) = 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 lost to the gun = 20%.
26
# Internal Ballistics What are Ballistic Abnormalities?
* Occasion-to-occasion Effect * The Warmer (Cold Gun) Effect * Order of Fire * Ballistic Hump
27
# Internal Ballistics - REMEMBER THIS QUESTION Pioberts law
The surface of deflagrating propellants will recede layer by layer in a direction normal to the surface.
28
# Internal Ballistics How can the round to round regularity of muzzle velocity be improved?
If burning finishes while the shell is still well back in the bore.
29
# Internal Ballistics What are the six (6) areas of distribution of energy when the gun is fired?
* Projectile, translational and rotational * Heat in the gas * Gun recoil * Driving band engraving and overcoming friction of the bore. * Unburnt charge and gases * Heat in the gun
30
# Internal Ballistics What is the effect of an increase in charge weight?
Pressure increases, ABP moves back, muzzle velocity increases, regularity in fall of shot improves.
31
# Internal Ballistics For the same weight of charge, what is the effect of increasing the propellant size?
Total initial burning surface of the propellant decreases. Pressure is lower at first, ABP moves forward in the bore, muzzle velocity decreases, regularity in fall of shot decreases.
32
# Internal Ballistics What is the effect of using a multi tubular propellant on internal ballistics?
The peak pressure is reduced but the projectile still gets good energy levels.
33
# Internal Ballistics What is the effect on internal ballistics of using a projectile of normal weight, but shorter and of larger diameter than normal?
The same muzzle velocity is achieved with a pressure which is everywhere less than with the standard shot.
34
# Internal Ballistics Examples of degressive burning
- Cord - Flake - Ribbon
35
# Internal Ballistics Examples of neutral burning
- Tubular - Cogged - Star Centered
36
# Internal Ballistics Examples of progressive burning
- Rosette - Multi-tubular
37
# Internal Ballistics What happens to the rate of burning of propellant if the pressure is increased?
It increases.
38
# Intermediate Ballistics Definition of Inermediate Ballistics
The study of the transition from internal to external ballistics that occurs in the vicinity of the muzzle.
39
# Intermediate Ballistics 2 phases of muzzle gas flow field
* 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.
40
# Intermediate Ballistics What is blast shock wave?
When high pressure gas is suddenly released from the muzzle, the out going noise primarily takes the form of an abrupt increased pressure known as blast shock wave
41
# Intermediate Ballistics - REMEMBER THIS QUESTION What 2 elements make up bottle shock?
* Barrel Shock – sides. * Mach Disc – front.
42
# Intermediate Ballistics - REMEMBER THIS QUESTION Types of Flash
* Pre-flash. * Primary flash. * Muzzle glow. * Intermediate flash. * Secondary flash.
43
# Intermediate Ballistics - REMEMBER THIS QUESTION What is muzzle flash
Flash is the light emitted in the vicinity of the muzzle by the hot propellant gases and the chemical reactions that occurs as the propellant gases mix with the surrounding air.
44
# Intermediate Ballistics What is pre-flash and why does it occur?
The flash prior to projectile exit - Escaping hot gases & propellant gases in front of the projectile
45
# Intermediate Ballistics What is secondary flash?
The large flash caused by the mixing of hot combustable material with the air.
46
# Intermediate Ballistics Why is it important to minimise secondary flash?
Can indicate position of the gun to the enemy and may cause temporary blindness to the gun crew
47
# Intermediate Ballistics - REMEMBER THIS QUESTION 3 main ways to reduce flash.
- Muzzle devices (Flsah suppresor) - Type of propellant - Propellant additives
48
# Intermediate Ballistics Types of muzzle devices (flash suppressors)
* Conical tube. * Slotted tube. * Bar type.
49
# Intermediate Ballistics Why do we use muzzle devices
* Reduce recoil. * Suppress flash. * Decrease report.
50
# Intermediate Ballistics Reasons for flash suppresion
* Reduce signature. * Reduces possibility of temporary blindness.
51
# Intermediate Ballistics How do most flash suppression devices reduce flash?
* Break up the Barrel Shock * Mach Disc
52
# Intermediate Ballistics Which type of propellant is used for flash reduction?
Triple-based propellant
53
# Intermediate Ballistics 2 main sources of muzzle blast
* Blast Shock wave * Flash blast
54
# Intermediate Ballistics 3 types of silencers
* Blast absorption. * Blast dissipation. * Blast containment and controlled release.
55
# Intermediate Ballistics What is blast?
Blast is effects produced by gas pressure waves in both intermediate and terminal ballistics
56
# Intermediate Ballistics What items can be used to reduce blast in small calibre weapons?
Silencers
57
# Intermediate Ballistics What is a bore evacuator?
Prevents propellant fumes from entering the crew compartment
58
# Intermediate Ballistics What is recoil?
Recoil is the rearward motion of the gun in reaction to the forward motion imparted by the projectile and propellant gases.
59
# Intermediate Ballistics Definition of bottle shock
Bottle shock is the air pushed out by the projectile in the precursor phase. The compressed air is put under pressure and forms a shock wave when exiting the barrel.
60
# Intermediate Ballistics What is the main blast field effect on projectiles
it can cause the projectile to yaw.
61
# External Ballistics Properties of the projectile
* Mass. * Calibre. * Nose Shape. * Spin Rate.
62
# External Ballistics Properties of the atmosphere
* Air Density. * Temperature. * Pressure.
63
# External Ballistics Definition of trajectory
The trajectory is the path taken by the centre of gravity of the projectile
64
# External Ballistics Types of drag forces
- Skin friction - Pressure drag - Forebody drag (shockwaves) - Excrescence Drag
65
# External Ballistics How to reduce pressure drag?
* Smooth shapes and rounded nose (subsonic) * Avoidance of sharp corners
66
# External Ballistics What is ballistic coefficient?
The measure of a projectile's ability to overcome drag.
67
# External Ballistics Ways to reduce base drag
- Boat tailing - Base bleed
68
# External Ballistics What is drift?
A projectile will deviate laterally from the original direction imaprted to it by the gun. This lateral deviation is called drift.
69
# External Ballistics What is drift made up of?
- Drift due to equilibrium yaw - for spun projectiles - Drift due to ritation of the earth.
70
# External Ballistics For a projectile fired in-vacuo, what angle of projection gives you the maximum range?
45 degrees
71
# External Ballistics What is meant by base drag acting on a projectile in flight?
Base Drag is caused by turbulent, low pressure region immediately behind the base of the projectile.
72
# External Ballistics What are the two major aerodynamic forces acting on the projectile, depending on Yaw?
* Crosswind * Drag
73
# External Ballistics Explain boat tailing in reduction of drag
Below the speed of sound skin friction and base drag are the principle causes of friction. To reduce base drag a stream line tail is added to the projectile. This process is called Boat Tailing. A boat tail is usually a truncated cone of the order of 1/2 to 3/4 calibre is length, and it reduces the area of low pressure to the rear of the projectile by allowing the air to flow more readily over the surface of the projectile.
74
# External Ballistics Explain base bleed in reduction of drag
This process involves the burning of a small amount of propellant fitted to the base of the projectile. The propellant burns at low pressure to create a jet of hot gas at the base of the projectile, which increases the pressure behind the projectile and reduces drag by up to 50%. The range increases associated with this method are between 10 and 30 percent. A more sophisticated version of base bleed is external burning which emits more gas through holes in the periphery of the projectile base.

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