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401-101 > AT SGT Ballistics > Flashcards

AT SGT Ballistics Flashcards

1
Q

What is the definition of Internal ballistics?

A

The study of operating processes from when the propellant is ignited until the weapon leaves the barrel

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2
Q

What is the all burnt point?

A

The point where all propellant has been consumed

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3
Q

What is shot start?

A

The point where the projectile begins to move

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4
Q

What is muzzle pressure?

A

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

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5
Q

What is muzzle velocity?

A

Projectile speed at exit from the barrel

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6
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 exit

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7
Q

What are the goals/objectives of internal ballistics?

A

Launch the projectile safely
Consistent performance between shots
Achieving the highest possible muzzle velocity

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8
Q

Explain the volume and temperature relationship on pressure

A

Increase volume causes less pressure
Increase temperature more pressure

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9
Q

What is Pioberts law?

A

When burning the surface of propellants recede layer by layer in the direction normal to the surface

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10
Q

How are the 6 energies distributed when a projectile is fired?

A

Projectile (translation and rotation) 32%
Residual heat of gas 42%
Heat lost to gun 20%
Recoil of gun 0.2%
Engraving the driving band / barrel friction 2.8%
Unburnt charge and gas 3%

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11
Q

What can cause the variations in the effects of ballistics? (7)

A

Charge weight
Propellant size
Chamber capacity
Ignition temperature
Shot start pressure
Bore area
Multiple variations in combination

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12
Q

What is the effect of an increase in charge weight?

A

Pressure increase
All burnt point moves closer to ignition
Muzzle velocity increase
Regularity in fall of shot improves

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13
Q

What is intermediate ballistics?

A

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

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14
Q

What are 5 types of muzzle flash?

A

Pre-flash
Primary flash
Muzzle glow
Immediate flash
Secondary flash

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15
Q

Name 3 types of flash reductiontion methods?

A

Muzzle devices
Type of propellant
Propellant additives

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16
Q

Name 3 types of suppressors?

A

Conical
Slotted
Bar type

17
Q

What are the objectives of intermediate ballistics?

A

Launch the projectiles safely
Launch the projectiles with uniformity
Achieve the highest possible muzzle velocity

18
Q

What is muzzle energy?

A

The majority of energy is carried by the propellant gases in the form of heat, pressure and motion.

19
Q

Why do we use muzzle devices?

A

Reduce recoil
Suppress flash
Reduce report

20
Q

How do most flash suppression devices reduce flash?

A

Break up the barrel shock and mach disc

21
Q

What is a blast shock wave?

A

The abrupt increase of pressure from the sudden release of high pressure gas from the muzzle

22
Q

What are the 2 muzzle gas flow blast fields during firing?

A

Precursor
Main

23
Q

What are the 2 main sources of muzzle blast?

A

Blast shock wave
Flash blast

24
Q

What is muzzle flash?

A

The light emitted in the vicinity of the muzzle by hot propellant gases and chemical reactions with the gases and the air.

25
Q

How is the precursor blast field made up?

A

Blast shock
Bottle shock - barrel shock and mach disc

26
Q

The 4 burning characteristics of propellant compositions are?

A

Burning rate - rate granules reduce when burning
Pressure index - Coefficient burn rate at different pressures
Force constant - pressure generated in a volume
Co-volume - The volume occupied by 1kg of propellant

27
Q

What are the 2 parts of the blast shock?

A

Blast shock wave - caused by high pressure propellant gases
Flash blast - rapid temperature rise causing secondary flash causing gas pressure rise

28
Q

What can reduce blast shock?

A

Suppressors can reduce blast
Blast absorption
Blast dissipation
Blast containment and control release

29
Q

What is another name for fume extractor?

A

Bore evacuator

30
Q

What is recoil?

A

The rearward motion of the gun in reaction to the forward motion imparted by the projectile and propellant gases.

31
Q

2 most common means of stabilisation are?

A

Spin
Fin

32
Q

What is trajectory?

A

The path taken by the center of gravity of the projectile

33
Q

What are the 4 drag forces?

A

Skin friction
Pressure drag
Forebody drag
Excrescence drag

34
Q

What is excrescence drag?

A

Caused by articles protruding from the shell

35
Q

What is ballistic coefficient?

A

Measure of a projectiles ability to overcome drag

36
Q

What are the forces acting on the projectiles?

A
37
Q

What are the 2 gyroscopic forces?

A

Precession - circular yaw
Nutation - rosette pattern from the rotational forces on the projectile

38
Q

What 2 parts impart drift onto the projectile?

A

Spun projectiles due to equilibrium yaw
Rotation of the earth

401-101 (25 decks)

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