Summative Assessment 7 Flashcards
What are the Objectives of Internal Ballistics?
- Launch the Projectile safely
- Consistent performance between shots
- Achieve the highest possible muzzle velocity
Definition of Internal Ballistics
Scientific study of the operating process within the gun from the moment the propellant is ignited until the projectile leaves the barrel
Define Pioberts Law
Surface of burning propellant recedes layer by layer in direction normal to the surface
Characteristics of Propellants
- Burning Rate
- Pressure Index
- Force Constant
- Co-Volume
- Ballistic Size
- Form Function
How to improve muzzle velocity for round for round regularity
If burning finishes while the shell is still well back in the bore
What are the 6 areas of energy distribution?
- Projectile (translational & rotational)
- Residual heat of the gases
- Recoil of the gun
- Engraving the driving band/barrel friction
- unburnt charges and gases
- Heat lost to gun
4 Phases of Internal Ballistics
- Charge Ignition
- Combustion prior to Projectile motion
- Combustion up to all burnt point
- Gas flow and projectile motion after all burnt point to muzzle
Definition of Intermediate Ballistics
Study of the transition from internal to external ballistics that occurs in the vicinity of the muzzle
What are the 2 phases of the muzzle gas flow field?
- The precursor blast field that proceeds the projectile exit of the muzzle
- The main blast field that follows as high pressure propellant gases are ejected into the air
3 Main ways to minimise muzzle flash
- Muzzle Devices
- Choice of Propellant
- Propellant Additives
How do Flash suppression devices reduce flash?
• Break up barrel shock and Mach disc
What 2 elements make up bottle shock?
- Barrel shock
* Mach disc
What are the 5 different types of flash?
- Pre-flash
- Primary Flash
- Muzzle glow
- Intermediate flash
- Secondary flash
What does a bore evacuator do?
- Prevents propellant fumes from entering crew compartments
- Works by creating pressure differentials during and after firing
- High pressure propellant gases are stored in the evacuator as the round passes through the barrel
- As round exits muzzle the high pressure gases flow out the muzzle
- This May increase the secondary flash
What forces act upon a projectile?
- Drag
- Pressure
- Yaw
- Velocity
- Roll
What are ways to overcome forces of a projectile?
- Nose shape
- Base shape
- Base bleed
Definition of Terminal Effects
The study of projectile behaviour at the target
What are the fundamental elements of Terminal Effects?
- Kinetic Energy
- Projectiles Physical properties
- Target type
What factors can affect projectile penetration?
- Projo Velocity
* Density
How does ceramic armour prevent penetration?
By reducing the projectile nose mass whilst projo core decelerates
What are the 4 types of Drag?
- Skin Friction
- Forebody Drag
- Pressure Drag
- Excrescence
