Theory of Design Flashcards
Definition of a grenade
a grenade is a small explosive store designed for projection by hand or from a personal weapon or a launcher may be used
Categorisations of grenades
Categorised by the intended means of delivery , and the payload
- hand thrown
- projected (rifle / gun fired)
- discharger (weapon / vehicle launched)
Grenade payload types
HE anti pers (offensive - defensive) HEAT and Dual Purpose (Heat and Frag) Smoke (signalling and screening) Chemical / Irritant Flash or noise Incendiary Prac Ilum
Typical grenade components
Body Filling Frag Fuze cavity Fuze
Fuze components
Safety Pin Fly off lever Spring Striker Detonator Delay Pellet
Offensive grenades
To stun or disorientate
Rely on blast effect
Defensive grenades
Project frag at high velocity
Used fm a defensive position
40mm low pressure cavity
used to lower pressure in the cart case so the round is fired at a lower velocity, and there is less recoil to the firer
Definition of SAA
Ammo for weapons such as pistols, rifles and machine guns below 20mm calibres
Parts of an SSA round
Cart Case
Ignition system
Propellant charge
Bullet/projectile
SAA Cart case purpose:
- holds propellant charge, incorporates ignition system, retains bullet, provides obturation
- is influenced by the roll of the ammo, the type of weapon, bullet design, and ignition system
SAA Cart case must be:
- elastic to expand and contract,
- resist corrosion
- withstand transportation and handling
- have a hard base and soft mouth
SAA Cart Case types:
Rimmed, semi rimmed, rimless
SAA Ignition System
Berdan - cap and anvil
Boxer - cap and separate anvil
Rimfire
SAA propellant types
Single and double based
SAA Bullets:
- design is governed by role
- short range = low velocity, snub nose
- long range = shaped for aerodynamics, streamlined
length is limited by external ballistics - spin stabilised becomes unstable over time
Solid or filled
What is ‘set up’
the expansion of the rear of the bullet combined with setback.
in this position, the cart case has expanded from the expansion of gas as the propellant combusts, and the bullet has engaged the rifling
FFR Principles
When a gas is compressed within a container, pressure is transmitted in all directions. If an opening is present and pressure is maintained by burning propellant, the pressure at the closed end is greater than that at the open end. Energy expended gives velocity to escaping gasses, causing the rocket to move in the direction of the closed end.
FFR consists of two sections:
Motor and Warhead
FFR Motor consists of:
Casing Combustion chamber propellant ignitor nozzle/s find (if not spin stabilised)
FFR Nozzle - Describe
‘De Laval Nozzle’ = Convergent-divergent type
Purpose is to convert heat and pressure to KE
Compresses gas to provide thrust / forward propulsion
High pressure sub sonic gas transferred to low pressure supersonic gas
Describe Thrust Alignment (FFR)
where the thrust doesn’t pass through the centre of gravity of a rocket, causing it to pitch or yaw.
Cg changes as fuel is consumed/depleted
How to overcome Thrust Alignment (FFR)
spinning the rocket during motor burn reduces the affect of thrust alignment, but too fast and the effects will be increased
mitigate by:
- manufacturing to closer tolerances
- impart slower rate of spin
- reduced rocket motor burn time
- addition of fins
Definition of mines
An explosive or other material normally encased, designed to destroy or damage vehicles, boats or aircraft, and designed to kill, wound or incapacitate personnel.
May be detonated by the action of the victim, passage of time, or by controlled means.
