Summative 4 - Cartridges and Projectiles Flashcards
Non-Metallic materials: Natural fiber
List
List the 4 main natural fibres used in EO
CELLULOSE
SILK
WOOL
RUBBER
Non-Metallic materials: Cellulose
List/Definition
Define cellulose,
What are the two common forms of cellulose and what are they used in?
Definition :
- Polymeric substance found in vegetable matter.
Classed as harmless with explosives unless mixed.
Types and uses:
- Cotton.
Used for cotton charge bags. - Wood / paper.
Used for cardboard in pyrotechnics.
Cardboard used extensively in pyrotechnics.
Non-Metallic materials: Silk
List
What are the 6 main properties/considerations of silk
Protein structure.
Stable.
Expensive.
Used to tie bundles of cordite to form propellant charges.
Make bags for loose prop charges.
No residue left as with cotton.
Non-Metallic materials: Wool
List
What are the 4 main properties/considerations of wool
Protein based.
Shallon (a type or blend of wool) was used as gunpowder igniter.
Today used for felt pads.
Disadvantage:
Very high water absorption rate.
Non-Metallic materials: Rubber and synthetics rubbers
List
What are the 3 main properties/considerations of Rubbers
Natural rubbers are avoided due to deterioration in extreme temperatures.
Silicone rubbers are reasonably resistant to climatic extremes.
Rubber composition bitumen is widely used in Squash Head.
Non-Metallic materials: Plastics
List
What are the 3 main properties/considerations of Plastics
- Includes resin & plastics.
- Finished product will contain substances other than the basic polymer.
- Two main types of plastic:
Thermoplastic.
Thermosetting plastic.
Non-Metallic materials: Plastics
Definition / List
Define a Thermoplastic (2 points), and give an example.
- Soften on heating and re-harden on cooling, allowing them to be re-shaped.
- Number of times for re-shaping is restricted due to the plastic degrading.
Cordite is a thermoplastic in which the properties of the base polymer NC, have been modified by plasticisation.
Non-Metallic materials: Plastics
Definition / list
Define a thermosetting plastic (3 points)
Plastics that are acid insoluble and incapable of being softened by heat.
Used in casting of non-metallic land mines and glass fibre rocket motor cases.
Higher physical properties than steel but lighter.
Non-Metallic materials: Plastics
List
What are two advantages of engineered or improved plastics
Higher tolerance than normal plastics.
Most are fibrous reinforced which improves their performance.
Non-Metallic materials: Paints and varnishes
List
List the seven arbitrary and unrelated points on Paints and Varnishes.
- Must not react with explosives.
- Copal varnish.
To protect inside of shells against ammonium nitrate. - Shellac.
To protect brass cart cases against nitrous oxide (produced by cordite) - Varnishes based on bitumen.
- Developed for coating iron and steel surfaces of HE stores.
- Cementing in cardboard closure caps.
- Slow drying and all excess must be removed:
Solvent / air diesel effect.
Can be disastrous if the solvent is flammable.
Non-Metallic materials: Adhesives, Cements, and Luting
List
List the 4 common properties or requirements of adhesives, cements, or Luting
- Must not react with explosives.
- Must have strength and be water resistant.
- Permanent.
Adhesives or cement. - Temporary.
Luting (soft setting compositions).
HE shell filling techniques: Methods of filling
List
List the 4 main filling techniques and their sub-components
- Casting;
Straight pour
Creamed
Liquid and biscuit - Pressing;
Pressing
Incrementally into case
Pre pressed charges
HE shell filling techniques: Methods of filling
List
List the 4 main filling techniques and their sub-components
- Casting;
Straight pour
Creamed
Liquid and biscuit - Pressing;
Pressing
Incrementally into case
Pre pressed charges - Extruding
Direct extrusion into case - Pre forming / cocooning
Land mines
HE shell filling techniques: Casting and extruding
List
List the 5 consideration of casting and extruding
CCSSD
Cooling Range
Shrinkage
Structure
Cooling rate
Dust migration
HE shell filling techniques: Casting and extruding
List
List the 3 main disadvantages of hot/melt fillings
Shrinkage
Cracking
Dusting
HE shell filling techniques: Casting and extruding
List
List the ways of overcoming the following disadvantages/drawbacks of hot/melt fillings:
Shrinkage
Dusting
Cracking
Shrinkage
- Encapsulation
- pre-cast encapsulation
Dusting
- Terylene
- Glass fibre
- add lubricant
Cracking
- additives
- nucleating
- strenghtening
- plasticising
- seeding
- in conjunction with nucleating
HE shell filling techniques: Pressing
List
In addition to the separation of increments of pressed explosive, what 5 other disadvantages arise with pressing?
Tooling cost
Size limitations
Density gradients
Projectile design
Accuracy
HE shell filling techniques: Shell linings
List
What are the 3 considerations of shell linings?
The metal of which they’re made,
The protection of the fill,
and the ensuring the adhesion of internal coatings
Corrosion and Season Cracking:
List
List literally every element that alloy with iron/steel
Aluminium Bismuth Boron Chromium Copper Lead Manganese Molybdenum Nickel Silicon Sulphur Titanium Tungsten Vanadium
Corrosion and Season Cracking: Metals
List
List some more metals and what they can alloy with/are alloys of.
- Steel
Iron with Carbon as the major alloying element - Brass
Is Copper with the major alloying element being Zinc - Aluminium
Any of the following elements may be the major alloying
element: Copper, Magnesium, Magnesium & Silicon or Zinc - Mazak
Magnesium + Aluminium + Zinc and (K)opper
Primarily Zinc with the major alloying element being
Aluminium.
Corrosion and Season Cracking: Defects
List
List the 2 major types of defects found on metals/metal alloys
- Mechanical
Cracking due to stress - Chemical
Corrosion due to impurities
Corrosion and Season Cracking: Annealing
List
What is annealing?
Why i it useful
Heating of a metal in order to relieve work stresses.
It creates larger metal crystals, which make the metal softer.
Can be used to prevent mechanical defects, eg around the neck of a cartridge neck once formed.
Corrosion and Season Cracking: Defects
Definition
Define season cracking
Stressed areas of metal cracking due to the affect
of ammonia forming Cuprammonium during storage
in either hot or cold temperatures
Corrosion and Season Cracking: Defects - corrosion
List
List the definition, cause, and factors affecting rate of corrosion
- Definition:
The conversion of metal to a non metallic state. - Cause:
Chemical reaction - Rate or Corrosion:
Ambient air temperature
Humidity
Chemical impurities in the packaging material
Corrosion and Season Cracking: Defects - corrosion
List
List 5 types of corrosion
- Rust - (iron Oxide)
- Aluminium oxidation
- Cupric Azide contamination (corrosion of Lead Azide in moisture, and subsequent acid reaction with CU case, creating Copper Azide)
- Zinc Exudation / Free Copper (copper dissolves out of brass, creating areas of zinc deficient copper, and causing pores)
- MAZAK contamination (MAZAK is used in fuze bodies, breakdown will make unreliable, inoperable and dangerous fuzes.)
Corrosion and Season Cracking: Inspection, Sentencing and Repair
List
What must be done after cleaning a cartridge?
Wiped clean with Acetone or Alcohol
Wiped with a clean dry cloth
Cleaned steel repainted
Corrosion and Season Cracking: Inspection, Sentencing and Repair
What makes a cartridge unserviceable?
pitting or flaking is present
Corrosion and Season Cracking: Inspection, Sentencing and Repair
How do you remove corrosion from cart
cases?
Use of white spirit or light grade emery paper
If the corrosion is severe sentence ammo according
to inspection pam
Primers, Igniters and Tubes: Primers - Percussion
Definition
Explain how Percussion primers function
Functioned by a mechanical blow of a striker onto the percussion cap assembled in the base of the Primer.
Small flash given by the percussion cap is picked up an amplified by the gunpowder charge in the magazine portion of the primer.
Primers, Igniters and Tubes: Primers - electric types
List
List the two broad types of electric primers and define each
Bridge wire type
- Initiation is achieved by passing an Electric Current through an insulated copper wire & bridge, firing a priming composition which surrounds the bridge.
Conducting cap
- Conducting cap composition which is fired by passing an electric current through the cap filling.
ADV:
Possibility of Misfires as a result of a broken bridge wire is eliminated & assembly is simplified.
Primers, Igniters and Tubes: Primers general
List
List the 5 design features and requirements of a primer
Produce Sufficient Flash to ignite the propellant.
Pass the flash evenly over the propellant.
Be self obturating, externally and internally.
Protect the Gunpowder & propellant from moisture.
Flush fitting Screwed / Press fit.
Primers, Igniters and Tubes: Primers - Percussion
List / definition
List and define the 5 components that make up the construction of of a percussion primer
Body
- Contains all components.
Cap
- Holds initiating composition.
Anvil
- Shaped metal component is located above the Cap.
- Provides the resistance to the crushing action of the Striker which cause the composition to ignite.
Has flash holes for the passage of the Flash.
Contains the seating for internal obturating device.
Plug
- Provides the fire channels through which the flash passes to the magazine.
- Retains cone/ball of the sealing device.
Magazine
- May be recess in body or be a separate cylinder
Primers, Igniters and Tubes: Primers - Perscussion
Definition
Define Internal and an external obturating system
External
-Achieved by the expansion of the wall of the primer body against that of the Cart Case.
Internal
- Employing some form of stopper in the body, which on the ignition of the Magazine effectively plugs any attempt by the gases to escape rearwards.
- Ball Seal.
- Cone Seal.
Primers, Igniters and Tubes: Primers - Percussion
List
List the sequence of events in the percussion primer when fired.
Striker/Firing Pin strikes the Cap.
Crushes the initiating composition against the anvil.
Flash passes through the Firing Channels in the anvil & plug to the Gunpowder in the Magazine.
Magazine Fires, Primer Body Expands against the Cart Case, thereby ensuring external obturation.
Ball or Cone is forced back into the fire channels internal obturation.
Primers, Igniters and Tubes: primers - bridge wire
List / define
List and define the 4 parts of a Bridge wire primer
Base
- Screw threaded externally to engage in the Base of the Cart Case.
- Interior is bored & screwed threaded to take an Ebonite Cup, contains the contact piece & bridge wire.
- Recess is formed in body to hold small QTY guncotton dust around the bridge & gunpowder pellet above it.
- Forward end of body is screw threaded to accept the Magazine.
Contact Piece:
- The initial Contact which is housed in the Ebonite Cup.
Bridge:
- Consists of a short length of iridio platinum wire, both ends of which are secured to the Bridge plug.
- One end is attached to acopper wire runningdown the insulated centre of the body to a contact piece.
- The other to an earthed pole
Magazine:
- Separate cylindrical brass container.
- Holds GP.
Primers, Igniters and Tubes: Primers - bridge wire
List
List the sequence of events of a bridge wire primer when fired
Round loaded into gun, breech closed, needle moves forward on to the Primer Contact.
On Firing ,current flows through the needle contact
piece & insulated copper wire to the primer, cart case & gun to complete the circuit.
Bridge wire heats thus igniting the gunpowder dust gunpowder pellet magazine.
Primers, Igniters and Tubes: Primers - Bridge wire
List
List the 2 obturation forms for Bridge wire primers
External
As for other primers.
Internal
Copper bridge plug, setting back into the cone
seating in the base.
Primers, Igniters and Tubes: Primers - Conducting cap
List / Defitnition
List the 4 components of construction of a conducting cap and define them.
Base
Pole unit
Cap
Magazine
Base:
- Screw threaded externally to engage in the base of the cart case.
- Remainder of Body screw threaded on a reduced diameter for attachment of the magazine.
- Interior is bored & screwed threaded at the rear to house a Plastic Insulating Cup, containing a Brass contact
- piece & Pole Unit.
- Forward portion of Body recessed & screw threaded to accommodate a conducting Cap & a Closing Plug.
Conducting Cap:
- Brass Pole, tapered towards the rear which has a plastic insulating sleeve moulded to it.
- Drilled at the forward end to house a small Phosphor Bronze Spring , which ensure continuity of the Circuit between the conducting cap pole.
Cap:
Incorporates a brass pole piece which is insulated and surrounded by the Conducting Cap Composition.
Magazine:
- Separate cylindrical brass container. Holds GP.
Primers, Igniters and Tubes: primers - Conducting cap
List / define
List and define the 2 types obturation for conducting cap primers
- External
As for other primers. - Internal
Tapered pole unit setting back into a corresponding
recess in the base.
Primers, Igniters and Tubes: primers conducting cap
List
List the sequence of events of a conducting cap primer when fired
Round loaded into gun, breech closed, electric needle moves forward on to the Primer Contact.
On Firing , current flows through the needle contact piece & pole unit to the pole piece of the cap.
The filling in the cap is a conductor due to the inclusion of graphite, permitting current to pass through this to the brass distance piece & outer case of the cap, and back through the body of the base, Cart Case, gun to complete the circuit.
Heating occurs, composition ignites to produce a flash magazine.
Primers, Igniters and Tubes: Tubes
List/define
Where is a tube used and what dos it do
Used with separate loading bagged propelling charges.
Produce a flash sufficient to ignite the igniter.
Primers, Igniters and Tubes: Tubes
Definition
Explain how the obturation works with a tube
Tapered body of the tube is closed.
On firing, the thin wall of the tube expands against wall of the vent.
Head of tube is supported during firing by the striker lock, which prevents any movement of the tube.
Primers, Igniters and Tubes: Igniters
List
List the three types of igniters
Two consisting of supplementary charges of gun powder used to augment the flash from primer or tube.
Third being used in solid rocket propellant motors to ignite propellant.
Primers, Igniters and Tubes: Igniters
List
List the two types supplementary types of igniters
- BL Charge Igniters;
Attached to end of BL charges and whose function is to ensure the charge is ignited. - Igniters, cartridges;
Supplementary charge of gunpowder used to amplify flash produced by the primer.
Ignition of the propellant at centre of charge.
Tracer and tracer ignition: Trace general
List
What is the purpose of tracers?
Emit light.
May be used as a Self destruct.
Tracer and tracer ignition: dark ignition
List
What are the 2 purposes of dark ignition
Prevent the firer being dazzled by the brilliant flames emitted.
Reduce the possibility of the position of the gun being pin pointed by enemy observation from a
flank.
Tracer and tracer ignition: Tracer general
List
List the 4 requirements of tracer composition
Luminosity
Strength
Consistency of Performance
Ease of Ignition
Tracer and tracer ignition: Tracer general
List
What are the two means of ignition?
Direct ignition
- A cap sets back onto an anvil to initiate the igniter composition
propellant ignition
- Ignited by hot propellant gasses on firing
Tracer and tracer ignition:
List
What are the 3 classification of tracers
Tracer projectile
tracer and igniter projectile
integral tracer
Tracer and tracer ignition: Class - Tracer Projectile
List
A Tracer projectile is made of a steel or metal rod, with internal or external filling.
List how the fitting is
secured:
Sealed:
actioned
Method of Securing:
- Threaded externally to screw into base.
- Threaded internally for attachment to a screw treaded spigot.
- Separate screws passing trough the tracer body.
Method of Sealing:
- Brass or Celluloid discs or cups.
- Sealing methods vary considerably.
- Nitro Glycerine and Carbamite.
- Bakelite discs.
Action:
- Sealing arrangements are ruptured or consumed by propellant gases.
- Priming composition ignited.
- Ignites tracing composition.
Tracer and tracer ignition: Class - Tracer and igniter projectile
List
What are components and function of a Tracer and Igniter projectile
Steel or brass rod.
A separate component issued assembled with projectile.
Dual Function as a Self Destruct.
Tracer and tracer ignition: Class - Integral tracer
List
In what type shot is integral tracer used?
Only in solid shot, pressed into the shot and is integral to the ammunition
Metals and alloys: Metals
Definition
What is a metal?
Key points/words
Elemental - being a single element
crystalline structure when solid
characterised by ductility, conductivity, reflective etc
Metals and alloys: properties
Definition
Define hardness, malleability and ductility
This is perhaps the most important property of any
metal along with malleability and ductility. Hardness is the measure of a metals ability to resist deformation.
Malleability is the ability of a metal to be shaped
using forces without breaking the structure of the
metal.
Ductility is the ability of a metal to be drawn out in to
an elongated form again without affecting the
structure of the metal.
Metals and alloys: properties
Definition
define coefficient of expansion
This is the measurement of the amount a metal expands at a given temperature and when taken along with the elasticity of a metal
This particular property is the reason why brass is used to manufacture cartridges.
Metals and alloys: definitions
Definition
What is metallurgy?
Metallurgy is the exact science and
technology of the use of metals:
- The process of producing metals by extracting them from their base ores.
- Refining and purifying these metals.
- The study of the physical and chemical properties of these metals.
- The mechanical working of these metals.
Metals and alloys: definitions
Definition
What are 4 properties of copper?
What 5 things is copper used for? DDSSC
Properties:
- Metallic element that is ductile and malleable and one of the best conductors of heat and electricity.
- Copper can be found as either native copper or as part of other minerals.
- Exposed surface has a reddish orange tarnish.
Uses:
- Driving Bands
- Detonators
- Shaped charge liners
- Cartridge Cases
- SAA jackets (gilding Metal)
Metals and Alloys: definitions
List
What are the typical properties of brass
List and define the different alloys of and ratios of copper zinc alloys.
What two metals are in bronze?
Brass is harder and stronger than copper,, it is malleable and ductile, non-magnetic, and melts at 900-940 degrees
Cartridge Brass
- 70% Copper 30% Zinc
Gilding Metal
- 95% copper and 5% zinc
Admiralty Brass
- 69% copper, 30% zinc, and 1% tin which inhibits dezincification in many environments
Bronze is, generally, copper and tin
Metals and Alloys: Properties of metal
List
What two things can reduce the conductivity of a metal?
impurities, even in small amounts
work hardening
Metals and alloys: properties
Definition
What temperature do most metals melt below?
1100 degrees C
Metals and alloys:
Definition
What is a metalloid
a metal with metallic properties and non-metallic properties
Metals and alloys:
Definition
What is specific gravity?
Specific gravity is the ratio of the density (mass of a unit volume) of a substance to the density (mass of the same unit volume) of a reference substance.
The reference substance is nearly always water for liquids or air for gases.
Metals and alloys:
Definition
What is anodising?
Anodising is an electrolytic passivation process used to increase the thickness of the natural oxide layer on the surface of metal parts.
The process is called “anodizing” because the part to be treated forms the anode electrode of an electrical circuit.
Anodizing increases corrosion resistance and wear resistance, and provides better adhesion for paint primers and glues than does bare metal.
Forms an oxide over the surface which provides the corrosion resistance.
Metals and alloys: Iron
Definition
What are the properties of iron?
A heavy, ductile, malleable, magnetic element that occurs naturally in meteorites and most igneous rocks.
It is one of the most common elements on Earth.
Metals and alloys:
Definition
Define alloys
Alloys are metallic substances that contain more than one chemical element.
Usually they comprise a number of metallic elements.
Alloys are sub divided into ferrous alloys (those that contain iron) and non ferrous alloys (those that do not contain iron).
Metals and alloys: Steel
Definition
Define steel
Steel is an alloy of iron and carbon, can be up to 1.7% carbon
Metals and alloys: Steel
Definition
Define steel
Steel is an alloy of iron and carbon, can be up to 1.7% carbon
Metals and alloys:
Definition
Define sintering
Compressing metal particles into a coherent solid body. Carried out under heat but at a temperature below the melting point of a metal.
Metals and alloys:
Definition
Define creep
A permanent change in the physical dimensions of a metal caused by the application of a continuous stress.
Metals and alloys:
Definition
What is hot working
A process of working a metal into a different shape while hot.
A metal that has the ability to be hot worked, will retain its toughness when worked, and not become brittle.
Projectile definitions, terminology:
List / define
Define round, projectile, component
ROUND
A complete assembly of a projectile (with or without fuze), a propellant charge in a cartridge case, and the means of igniting the propellant charge.
PROJECTILE
An object capable of being propel led by a force, normally from a gun, and continuing in motion by virtue of its kinetic energy.
COMPONENT
An item which is an integral part of a system, sub sy stem or equipment.
Projectile definitions, terminology:
List
List the three basic types of projectile design
Shot
Shell
Carrier
Projectile definitions, terminology: Description
Definition
Define body
The empty body or shot, with driving band, before filling with the payload or tracer or other components.
Projectile definitions, terminology: Description
Definition
Define head
The complete portion of the projectile forward of the shoulder (US term).
Projectile definitions, terminology: Description
Definition
Define base
The part of the projectile rear of the driving
band, the types are Boat or cylindrical tail.
it has either a Base plates or Base cover.
Projectile definitions, terminology: Description
Definition
Define Bands
Sections of the shell wall may be accurately machined to a greater external diameter than the rest of the shell body. Is located immediately rear of the shoulder and forward of the Driving Band.
the front bad is often referred to as the bourrelet
Projectile definitions, terminology: Description
Definition
Define Driving band
The attachment to the outside of the projectile, usually to the rear. Primary function to provide obturation and impart spin to the projectile.
Projectile definitions, terminology: Description
Definition
Ogive
The shaped part of a normal projectile from the shoulder forward. It is the main radius of the head.
US usage: the entire head.
Projectile definitions, terminology: Description
Definition
Define shoulder, cavity, and wall
SHOULDER
The junction of the Head with the rest of the Body.
CAVITY
The space or spaces within the projectile, which may
accommodate the payload.
WALL
That part of the shell body that surrounds the cavity.
Projectile definitions, terminology: Description
Definition
Define governing section, fuze hole/well, and Lip
GOVERNING SECTION
That part of the projectile forward of the Driving Band at
which the stress on firing is maximum.
FUZE HOLE /WELL
The portion of the projectile head or base designed to hold
a fuze.
LIP
The junction of the fuze well liner and the projectile body.
Projectile definitions, terminology: Terms general
Definition.
Define Windage, fuze, lifting plugs/rings
WINDAGE
The difference between the diameter of the bore and the diameter of the projectile.
FUZE
A mechanical Device usually incorporating safety and arming mechanisms with explosive components designed to initiate a train of fire or detonation.
LIFTING PLUGS / RINGS
Fitted to top of projectile for storage and transport, prior to fitting a fuze
Projectile definitions, terminology: Terms general
Definition
Define body releif, booster (exploder), adaptor
BODY RELIEF
Portion of the shell wall that is machined to a smaller diameter than the actual calibre of the round.
BOOSTER (exploder)
A high explosive intermediary device incorporating a safety arming mechanism, usually a shutter, which amplifies the shock wave from the detonator.
ADAPTOR
An adaptor is a device that is fitted into, on or to an item of ammunition, to allow the fitting of a part or component which would not otherwise fit.
Projectile definitions, terminology: Terms general
Definition
Be familiar with the following terms Grommet Burster Bursting Charge (main charge) Canister Base Ejection Exploder (booster) Base Detonating Fuze Magazine Gaine Smoke Box Base Emission O Ring Square Base
Great
Projectile definitions, terminology: Dimensions
Definition
Define:
Capacity
Charge/weight of ammo
Net explosive Quantity
Capacity
Charge Weight Ratio (bursting charge/filled weight).
Charge / Weight of Ammo
% of explosives in relation to its gross
Net Explosive Quantity (NEQ)
Total weight of explosives contained in an item.
Projectile definitions, terminology: terms, classification
list
List and give examples of 3 classes of projectiles, give examples of each
- Operational Projectiles: Shot (KE) Shell effect produced by payload Mortar Grenade Bullet
- Weapon Functioning / inspection: Bulleted Blank (SAA) Paper shot (Weapon test) Proof Gun functioning
- Training Projectiles: Practice Drill/Dummy Instructional Break up Sub cal
Projectile definitions, terminology: Terms, kinetic types
List
List 9 types of kinetic rounds
Armour Piercing
AP
Armour Piercing Capped
APC
Windshield
Penetrative Cap
Ballistic Cap
Armour Piercing Capped Ballistic Capped
APCBC
Armour Piercing Discarding Sabot
APDS
Semi Armour Piercing
SAP
Armour Piercing Fin Stabil ised
Discarding Sabot
APFSDS
Driving bands: Functions
List
List the 3 functions of a driving band
To centre projectile in bore and impart spin.
To prevent the forward escape of propellant
gases.
To assist in prevention of slipback of the
projectile when loaded at high elevations.
Driving bands: Requirements
List
List the 6 requirements for a driving band
No excessive pressure on the shell or barrel.
Cater for change in bore diameter (wear).
Remain firmly attached to the projectile.
Must not alter the ballistic shape of the projectile (engraved state).
Cause no excessive friction or bore wear.
Simple to make and fit.
Driving bands: positioning
List
Where is best to have a driving band fitted on a shell
In practise it is desirable to have the driving band positioned as near to the base as possible to achieve the steadiness in the bore but not effect performance of shell.
Driving bands: limitations of positioning
List
List the 3 limitations of positioning regarding driving bands
Driving band near to the base:
- Can cause eddy waves which will reduce performance.
Streamline shells (Boatailed): - Requires a band in front of the streamline.
Fixed Ammo:
- The driving band must be far enough forward to allow the projectile to be firmly secured to the cart case.
Driving bands: material
List
What are considerations for use of materials in driving bands
The metal used must be soft, to give the least wear
possible in the gun.
Must not be so soft as to strip under the rotational and
engraving process in the bore.
Copper has been found to be the best.
Driving bands: Materials
List
What material do the USA use for driving bands and why
USA prefer to use Gilding Metal (Cu 90% Zn 10%)
- Reduces “coppering” of the bore
- Zinc is a deoxidiser
- Eliminates impurities
- Economy of use of copper in wartime
- Slightly cheaper to produce
Driving bands: Materials
List
What are alternative materials hat have been used previously?
Alternatives were used during WWII due to
the shortage of copper:
Sintered iron;
Compressed & Heat Treated
Soft iron
Mild steel
Aluminium alloy
Magnesium alloy and
Early plastics
Driving bands: Attachment
List
List the two methods of attaching driving bands
Split Ring:
- A strip is cut to the required length,
- Formed into a ring;
- Ends butted together
- Pressed onto shell by a multi ram press
Solid Ring:
- A ring of the correct width is cut from a length of seamless copper tube
- Slipped over the shell
- Pressed in the same method as for split ring method
Driving bands: preventing twist
List
List and explain 2 methods of preventing twist
Wavy Rib:
- This method is easy to manufacture since the ribs can be cut in the same turning operations as the cutting grove
- Three or more chisel cuts across the ribs prevent the trapping of air when the band is pressed on
Knurling:
- This method may necessitate setting the shell up on a milling machine after the groove is cut.
- It is more difficult to ensure firm attachment with Knurling than wavy rib
Driving bands: Types of driving band
List
List the 5 types of driving bands
- Orthodox Band:
Rectangular in section
Height a little over groove depth
Width sufficient to give full rotation - Modern Band:
Designed with a high sealing flange for high
performance weapon systems - Double Band:
Easier than single to attach firmly to projectiles
Uses serrations to assist in lodging the projectile in the lands after ramming
More economic because less copper required (alleviates requirement for one large band) - Gas Check Type:
Employs an undercut
- Probert: Both Forward & Rear Bands Rear as a high flange Forward is a double and gives rotation Forward bands are grooved
Driving bands: Slip rings
Define
What is the purpose of a driving band
Made of various materials
Designed to ensure that the spin imparted by the weapons barrel does not reach a rate that would influence the fin stabilisation of a projectile
Or reduce the effectiveness of a hollow charge
Driving bands: List the requirements for a slip ring
List
Should breakup on leaving the barrel
Should breakup into particles small enough so as not to harm friendly troops
Chances of any fragments remaining in the barrel should be minimal
The ring should still engage the rifling and not soften under bore temperature
Driving bands: Slip rings
List
What are the common materials used to produce slip rings
Plastic:
- Nylon
Vulcanised rubber.
Polycarbonate:
- Makrolon
Driving bands: bore riding nubs / bands
Definition
What is the purpose of bore riding nubs / bands
Provide stability for streamlined projectiles
Driving bands: obtuarting bands
Definition
What is the purpose of an obturating band
Assist with gas seal behind driving band
Cartridge systems: Types
List
List the two Types of systems
Breech loading (BL) and quick firing (QF)
Cartridge systems: BL
List
Explain three 3 points on BL systems, and list three components
- The breech mechanism is generally heavy and opens rather like an oven door.
- Rearward obturation is achieved by the gun.
- BL guns are loaded with:
Bagged Charge system
Modular Charge System (MACS) - Consists of:
Tubes/primers
bagged charge
Projectile
Cartridge systems: BL systems
List
List the 2 advantages, and 2 disadvantages of a BL system
Advantages:
Less stowage problems / reduced length.
No Cart Case.
Disadvantages:
Slow loading process.
Slow rate of fire, Three components = slow process.
Cartridge systems: QF systems
List
List the three types of QF systems
QF Separate
QF Semi fixed
QF Fixed
Cartridge systems: QF
List
What is a QF system?
QF is a system in which the breech is usually closed by a simple sliding motion resulting in a higher rate of fire.
Rearward obturation is provided by the Cart Case.
Propelling Charge is contained in an
incombustible Cart Case.
Also called: “Ammunition Obturation” (AO)
Cartridge systems: QF
List
What 3 components make up a QF system
Cart Case with Primer.
Propelling Charge (can be Charge Bags ).
Projectile.
Cartridge systems: QF
List
What are the 4 requirements of a cartridge case
Protection of contents.
Provide efficient obturation.
Easy loading and extraction.
Able to house a primer.
Cartridge systems: Charge bags
List
What 3 things must the material of charge bags do?
Protect and contain the contents.
Be totally consumable.
Allow the flash from ignition to pass easily through.
Cartridge systems: QF
List
What are the requirements of charge bags
Non smoulder.
Non stretch.
Non wear.
Be insect, vermin and rot proof.
Cartridge systems: QF seperate
List
List the 4 characteristics of a QF separate systems
QF Separate (e.g. 105mm)
PROJ and Cart Case packed separately.
Loaded as two units.
PROJ is rammed before Cart Case is loaded.
Can be Adjustable charge.
Cartridge systems: QF seperate
List
List the 3 adv, and 4 disadvantages of QF separate systems
Advantages:
Less stowage problems due to length.
Replace damaged Cart Case.
Adjustable charge.
Disadvantages: Slow loading process. Slow rate of fire. Disposal of fired Cart Case. Fumes trapped in Cart Case.
Cartridge systems: semi fixed
List
What are the 4 characteristics of QF semi-fixed systems
QF Semi fixed (e.g. 105mm
PROJ and Cart case packed together.
Mated together and Loaded as one unit.
Projectile rammed by Cart case.
Adjustable charge.
Cartridge systems: QF semi-fixed
List
What are the 3 advantages and 2 disadvantages of QF semi-fixed system
Advantages:
Loaded as one unit.
Adjustable charge.
Projectile ramming unnecessary.
Disadvantages:
Disposal of fired Cart Case.
Fumes trapped in Cart Case.
Cartridge systems: QF fixed
List
What are the 4 characteristics of a QF fixed system
PROJ and Cart Case joined together.
Loaded as one unit.
Rammed as one unit
Charge not adjustable.
Cartridge systems: QF fixed
List
What are the 3 adv and 3 disadvantages of QF fixed system
Advantages:
Loaded as one unit.
Rammed as one unit.
Joined together, so no weak point.
Disadvantages:
Stowage problem due to length.
No charge adjustment.
Disposal of Cart Cases.
Propellant charges and trends: Fixed ammo
List
What factors affect eh choice of fixed ammunition
Fixed charge weight (direct fire).
High rate of fire / automatic loading.
All up weight and size of round should not make handling difficult.
Problem in obtaining a satisfactory case shell joint with a heavy projectile.
Required rate of fire of the system.
Extraction and ejection problems.
Disposal of fired cart cases.
Propellant charges and trends: semi-fixed and separate
List
What are the considerations with semi-fixed and separate systems
Charge can be adjusted so this type of system is used in most indirect fire weapons.
Ammunition is easily handled.
Stowage problems in AFVs may be eased.
Use of more than one type of charge.
Propellant charges and trends: bagged charges
List
This system uses obturation provide by the gun
What are tj
Propellant charges and trends: bagged charges
List
This system uses obturation provide by the gun
What are the characteristics of separate ammunition
No cart case to be extracted.
Breech slightly simplified.
Fume extractors can work more effectively.
Additional component loaded Tube vent.
Weight is less.
Easy charge adjustment.
Propellant charges and trends: bagged charges
List
What are the 4 types of bag charges
Equal
Unequal
Stem and Ring
Stem and Segment
Propellant charges and trends: bagged charges
List
What are the design considerations / requirements for charge bags
Be non smolder.
Be non stretch.
Be non wear.
Be entirely consumed on firing.
Leave no smouldering particles or residue.
Be insect / vermin / rot proof.
Be permeable to the flash from the tube.
Propellant charges and trends: charge bags
List
Design principles (2 points regarding the lowest charge) of charge bags
The lowest ch ar g e must be stable so it does not lose its shape when loaded alone and cause a misfire or delay in complete ignition.
The igniter, which is always fitted over the lowest charge, is made of the largest possible diameter.
Propellant charges and trends: charge bags
List
Design principles (2 points regarding the lowest charge) of charge bags
The lowest ch ar g e must be stable so it does not lose its shape when loaded alone and cause a misfire or delay in complete ignition.
The igniter, which is always fitted over the lowest charge, is made of the largest possible diameter.
Propellant charges and trends: Charge bags
List
List the 5 design characteristics of charge bags
Normally cylindrical in shape.
Bagged charge comprises an Igniter and Prop charge.
When propellant is in stick form, it is held by sewing silk or in the case of heavier charge loads, by silk braid.
When granulated propellant is used, it is filled loose.
Lifting beckets of braid are fitted to large charge bags to assist in lifting.
Propellant charges and trends: charge bags
List
What 2 materials have charge bags been made of?
Silk,
now cotton or terylene
Propellant charges and trends: Charge bag materials
List
What are the prerequisites of the igniter (small igniting pad on base of first charge)
Material which houses ignition is Shalloon. (legacy)
Closely woven to stop GP seepage.
Permeable to the flash from the tube.
The Igniter should cover the largest diameter to ensure that the flash impinges directly on the GP fill to ensure good, even burning of the main charge, hence the shape design.
Propellant charges and trends: de-coppering
List
What is de-coppering?
Explain the process - 3 points
Tin or lead foil is incorporated in the propelling charge of each round.
On firing, the foil melts and is sprayed against the copper deposits to form a brittle alloy.
This alloy is then cleaned away w hen the next projectile is fired.
Propellant charges and trends: Charge types
List
What are the 7 charge types - related to performance
Charge Types:
- Normal
Does not provide maximum ballistic performance.
Super:
Maximum permissible ballistic performance.
Reduced:
Provides lower pressures and lower velocity (Used for training).
Fractional:
For large BL charges, divided for ease of handling
Incremental:
for the variation of ballistic performance in QF howitzer and guns
Blank charge:
Charge of GP or prop of sufficient size to give a loud report for salutes and training
De-coppering charge:
tin or lead foil added to propellant charge for de-coppering charge
Propellant charges and trends: Trends - cart cases
List
What two types of new cart cases designs are being moved towards
define each
- Combustible
Material that is used up during the process of the combustion of the propellant. It is an inert material and does not contribute to the explosive process. - Consumable
Material that is capable of burning and contains ingredients that contribute significantly to the production of propellant gasses.
Propellant charges and trends: trends cart cases
List
What are the advantages of combustible and consumable cart cases
No spent cart case to be collected or extracted.
Less fumes.
Ammunition weight is less.
Easier to adjust charge.
Reduced barrel wear.
No cluttering at the gun site.
Propellant charges and trends: trends cart cases
List
What are the disadvantages of combustible and consumable cart cases
Lack of strength.
Residue left.
Additional components to load.
Chance for a “cook off”.
Ingress of moisture.
Propellant charges and trends: Trends cart cases
define
What are combustible cart cases manufactured from?
Combustible cart cases are manufactured from a mixture of NC fibres and inert cellulose with additives for stabilisation and strength.
Propellant charges and trends: trends - liquid propellants
List.
Liquid propellants are required to be pumped directly into the gun chamber, and involves a complete gun re-design.
What type of liquid propellant is favoured, and what are the two systems used?
- Mono propellants favoured.
- Two systems:
Regenerative system.
Travelling Charge Injection system.
Propellant charges and trends: Trends - Liquid propellants
Definition
What is a regenerative system? 4 main points
Involves continuous injection of propellant into chamber during required burning time of gun.
Similar to liquid fuelled rocket motor.
Problem of injecting spray into chamber where gas pressure is rising immediately after ignition.
Overcome by using the chamber pressure to force a perforated piston rearwards, thus forcing propellant forward via the perforations.
Propellant charges and trends:
Definition
Define a travelling charge injection system, 5 main points
Propellant loaded behind projectile.
Backed by perforated rodless piston.
Fuel injected rearward into chamber by forward movement of piston.
Charge propelled forward.
Piston & projectile leave muzzle together.
Propellant charges and trends: trends - liquid propellants
List
What are the advantages of a liquid fuel systems
Elimination of cart case.
Ease of manufacture, storage (in most cases), & transport.
Achievement of any specific range from a given elevation by precise metering.
Low vulnerability to ignition by enemy fire.
Easier use in AFV & in NBC conditions.
Reduction of smoke, flash & bore erosion.
No waste of propellant compared with normal charge increment systems.
Propellant charges and trends: trends - liquid propellants
List
What are the advantages of a liquid fuel systems
Elimination of cart case.
Ease of manufacture, storage (in most cases), & transport.
Achievement of any specific range from a given elevation by precise metering.
Low vulnerability to ignition by enemy fire.
Easier use in AFV & in NBC conditions.
Reduction of smoke, flash & bore erosion.
No waste of propellant compared with normal charge increment systems.
Propellant charges and trends: trends MACS
List
List the two main points of a MACS charges and its expanded name
MODULAR PROPELLANT CHARGE SYSTEMS (MACS):
Combustible cased.
Triple base propellant.
Recoilless Cartridges & Propellants: ammo design
List
list 3 points on RCL Ammo design
RCL charges classified as cased systems.
Do not obturate the breech.
Obturator replaced by VENTURI.
Recoilless Cartridges & Propellants: recoiless principles
List
What is Newtons 3rd law
what makes a weapon recoiless?
Newton’s Third Law: For every action, there is an equal and opposite reaction.
If two equal weights can be fired in opposite directions at equal velocity the weapon will be recoilless.
Recoilless Cartridges & Propellants: Recoiless principle
List
It is possible to use a counter shot of half the weight, if it can be fired at twice the velocity.
Today the counter shot is replaced by a rapid stream of very light gas.
The obturated breech is replaced by the venture.
Recoilless Cartridges & Propellants: RCL ammo design
List
List the 2 common designs of RCL ammo
Solid Cart Case with Blow out Rear Disc.
Perforated cart case system.
Recoilless Cartridges & Propellants: Blow out disc system
Definition
Define a blow out disc system - 5 main points
Primer located to rear side of cart case.
Can only be loaded one way Ensures primer & firing pin aligned.
On firing the Propellant charge is initiated.
Pressure builds, disc ruptures, projectile propelled forward
Propellant gases escape through breech hole & out through venturi
Recoilless Cartridges & Propellants: perforated case system
Definition
Define a perforated cart case system - 4 main points
Sheath surrounding propellant.
Annular Space.
Prop gases to escape through holes in cart case, into annular space, out through venturi.
Pre rifled projectiles:
- Lower pressure
- Reduce torque
Recoilless Cartridges & Propellants: RCL systems
List
List the 4 advantages of RCL systems
No Recoil
Low Weight
Man Portable
Mounted on Light Vehicles
Recoilless Cartridges & Propellants: RCL systems
List
List the 4 advantages of RCL systems
No Recoil
Low Weight
Man Portable
Mounted on Light Vehicles
Recoilless Cartridges & Propellants: RCL systems
List
What are the 3 disadvantages of RCL systems
Flash / Dust signature (BBDA)
Low Velocity
Large Propelling Charge
ERP, ICM, TGM: methods of increasing range
List
What are 3 ways of improving weapon performance
Longer barrel – weight increase to weapon
Higher chamber pressures – requires modification to weapon
Reduced projectile shot weight – reduces lethality
Methods not considered because of inherent problems
ERP, ICM, TGM: methods of increasing range
List
What are two forms of post firing boost?
Rocket assisted projectiles (RAP)
Ram jet Boosted projectile
ERP, ICM, TGM: methods of increasing range
List
What are 2 ways to improve the ballistic co-efficient of projectile
Reduce drag
- aerodynamics
- base bleed
Sub calibre discarding sabot
- spin or fin stabilised
ERP, ICM, TGM: methods of increasing range
List
What are 2 ways to improve the ballistic co-efficient of projectile
Reduce drag
- aerodynamics
- base bleed
Sub calibre discarding sabot
- spin or fin stabilised
ERP, ICM, TGM: methods of increasing range
List
If a new projectile is required - the required solution - what compatibilities does it require?
Propelling charges and fuzes
Handling, loading and storage
Bore pressures and muzzle velocities
Deployment
No reduction in equipment life
ERP, ICM, TGM: methods of increasing range
List
Reduced projectile shot weight. list 3 techniques of this form
- Reduced shot wieght - sub calibre reduced mass, increased velocity
- Extended range sub calibre (ERSC)
ERSC projectile for M109 howitzer Max range 22Km compared to 18Km M107 projectile
Aerodynamic shape reduced payload from 7.5Kg to 3.6Kg
- Extended Range Sub Bore (ERSB) Wider and Longer than predecessor Less than 155mm calibre Bore riding nubs Discarding driving band Good aerodynamic qualities, less lethal
ERP, ICM, TGM: methods of increasing range
List
In a RAP system a rocket motor is inserted into rear of projectile and ignited after ejection
List the RAP activation and action - 5 points
Rocket cap removed prior to loading
On firing propellant gases ignite delay composition – 7 sec delay
Delay ignites rocket igniter and main rocket motor propellant
Boost phase – 2 secs, Sustain – 7 secs
Propellant gases released through venturi
ERP, ICM, TGM: methods of increasing range
List
List the 3 disadvantages of RAP
Lethality – 25% increase in range reduces lethality. Projectile explosive content reduced to 7.3Kg
Accuracy – Ignition and burning of rocket motor consistency. Gun firing stresses can distort rocket motor causing irregular burn
Cost – Considerably more expensive than conventional ammunition
ERP, ICM, TGM: methods of increasing range
List
Define a base bleed function 5 points
Non-ballistic solution achieved by generating gases and filling the vacuum at the base of the shell during flight
Solid grain propellant ignited by propellant on firing
Burns slowly to fill vacuum which increases air pressure
Does not propel round, it eliminates drag
Base drag reduced by 70%, increase range by 10% – 20%
ERP, ICM, TGM: methods of increasing range
List
List the three advantages of base bleed compared to RAP
Base bleed can achieve similar results in range as RAP and maintain 20% charge to weight ratio
Has no adverse affect on accuracy
Can be housed in conventional or ERFB projectile
ERP, ICM, TGM: methods of increasing range
List
Why have ram jet systems not been developed for service?
Not been developed for service use due to high cost, complexity and serious reduction in useful payload.
ERP, ICM, TGM: methods of increasing range
List
Improving ballistic co-efficiency is achieved by what changes in projectiles
Modern projectiles have greater length to diameter (better flight and heavier peayloads)
Best design having an ogive forward of driving band
Profile reduces head resistance, increasing range
Boat tailing reduces base drag
ERP, ICM, TGM: methods of increasing range
List
Extended Full Range Bore (EFRB) is a further development of ER sub bore. List 3 advantages to welding nubs on these and 4 disadvantages for machining the shape of the nubs
- Advantages to welding:
Mild steel interface to rifling (the nubs are softer - less wear)
Minimum wear
Welding technique proven
- Disadvantages of machining: Low alloy steel High wear Reduction in body strength Reduction in fragmentation
ERP, ICM, TGM: improving lethality
List
List 4 ways of improving lethality
Large Free Flight Rockets (FFR) being fired in salvoes
Automatic loading systems for Self Propelled (SP) guns
Guided projectiles and terminally guided submunitions
Unguided sub-munitions from conventional shells – Improved Conventional Munition (ICM)
ERP, ICM, TGM: improving lethality
List
Sub munitions M483A1 - HE can be improved by sub-munitions
Explain the function of an M483A1 shell
- Carries 49 sub munitions
- Small shaped charge warhead
- Bomblets expelled through base of shell
- Each bomblet has a simple fuze by an aerodynamic streamer
- Most sub-munitions detonate on striking the ground
Fragmentation lethal radius – 6m, improved by internal design of bomblet casings - Lightly armoured vehicles penetrated by shaped charge
- Round is most effective against troops in the open supported by lightly armoured vehicles
ERP, ICM, TGM: improving lethality
List
What are the disadvantages of the 155mm M483A1
Complex payloads unable to withstand setback forces on highest charges so range is limited
Maximum range of M483A1 17Km
Conventional Base Bleed 30Km
Conventional 24Km
ERP, ICM, TGM: improving lethality
List
List the functioning and use of USA 155 M718 remotely delivered mines
6 main points
The U.S.155mm M718 carries nine M70 mines
Double sided mines
Miznay Schardin for belly attack of tanks
Electronic magnetic influence fuzes
Requires many rounds to create a minefield of sufficient depth and density
Task best suited to rockets
ERP, ICM, TGM: improving lethality
List
What is an example of an Australian used improved lethality munition
Projectile SMArt 155mm DM702A1
ERP, ICM, TGM: improving lethality
List
What are two other ways of improving lethality against pers
Flechettes
pre-formed frag
ERP, ICM, TGM: improving accuracy
List
What has led to the development of Terminally guided munitions
Artillery depends on saturating an area to suppress or destroy the target
Lack of terminal guidance limits effectiveness against hard targets
ERP, ICM, TGM: improving accuracy
List
What disadvantages are there to Er munitions?
increases projectile cost
Increases cost of target acquisition
Reduces payload
Reduces accuracy – accuracy is proportional to range
ERP, ICM, TGM: improving accuracy
List
The disadvantages of ER munitions led to what development?
Terminally Guided Munitions – Cannon Launched Guided Projectiles (CLGP)
ERP, ICM, TGM: improving accuracy
List
What issues were evident in the employment of CLGP - copperheads?
Target must remain visible
Forward observer vulnerable
Dedicated communications to guns firing CLGP
Terminal guidance can be affected by atmospheric conditions and low cloud cover
Suited for specialist missions where cost of projectile can be justified
- 1 x CLGP Vs 200 fuzed conventional
ERP, ICM, TGM: improving accuracy
List
Explain the function of a Sense and Destroy Armour (SADARM) shell
A fuzed projectile ejects 3 or 4 sub munitions
Fires EFP once aligned with target
Searches area using Infra Red (IR) beam
Deployed parachute slows munition
ERP, ICM, TGM: improving accuracy
List
Explain a terminally guided munition - Low cost corrected munition
Based on conventional munitions
Fitted with a fuzing system to rake or align projectiles trajectory to the pre-set coordinates
Cartridge case design: materials
List
What are the 3 reasons we use brass for Cart Cases?
Performs well in most equipment.
Metallurgy and techniques are well know.
Does not corrode to give hard abrasive particles.
Cartridge case design: materials
List
Aluminium, steel, plastic can also be used for cart cases
A cart case needs to be able to withstand extraction without jamming, and also support the projectile
What 6 material properties does a cart case material need to have?
Strong and easily deformable with good recovery.
Must not be prone to cracking during fabricationn and storage.
Provide sufficient strength at the base and give a hardness gradient along its length.
At the mouth it must be soft enough to deform.
At the mouth it must be soft enough to deform easily.
Base needs to be much harder to allow easy extraction.
Cartridge case design: Attachment
List/define
List and define the three ways which a projectile is attached to a cart case
Coning
The mouth of the cartridge case is turned into a groove or cannelure situated around the base of the projectile, just below the driving band.
Canneluring
Canneluring requires the pressing of the mouth of the case into a groove or cannelure, near the base of the projectile. Canneluring can be spaced or continuous.
Coning & Canneluring
Coning and canneluring employs both the above methods. It gives a firm joint for the larger equipment’s. More recently, to give greater sealing against damp, a rubber sealing ring has been incorporated between the projectile and cartridge case.
Cartridge case design: Methods of filling
List
List 3 methods of filling propellant into a cartridge
Loaded directly or into charge bag or bags.
Charge bags used in multi – charge systems.
Charge bag may be used where charge weight is small in relation to the volume of the case.
Cartridge case design: CCC
List
How can a Combustible cart case reduce barrel wear? What other effect does this have
Suitable material gives a boundary layer of gas which is cooler that the propellant gas.
Reduced cook off with low charges
Cartridge case design: CCC
List
What are CCC typically made of?
Nitrocellulose, Kraft paper and resins, resembles hard cardboard.
Cartridge case design: Charge selection
List
What 8 factors affect charge type selection of fixed amo
Fixed Ammunition:
Fixed charge weight direct fire.
Can be used in automatic weapon/loading systems.
All up weight and size should not make handling difficult.
Problem in obtaining case/shell joint with heavy projectiles.
Required rate of fire of system.
Extraction and ejection problems.
Disposal of fired case.
Cartridge case design: Charge selection
List
List 4 factors affecting charge choice for seperate ammo
Charge can be adjusted indirect fire.
Ammunition is easily handled.
Stowage problems in SP/AFVs eased due to reduced length compared to fixed ammunition.
Use of more than one type of cartridge super and normal.
Cartridge case design: charge selection
List
List factors affecting selection of:
Cased charge - 3
bagged charges - 6
CCC - 3
CASED CHARGES:
Propellant is better protected.
More robust and easily handled.
In large calibres weight of case can be an embarrassment.
BAGGED CHARGES: No spent cases to be extracted. Breech design simplified. Fume extractors work more effectively. Additional component has to be loaded tube vent. Ammunition weight is less. Charge adjustment multi charge system.
CCC:
Cases are ridged.
Offer more protection than bagged charges.
More susceptible to accidental initiation.
Carrier shells: Definitions
List
Define a carrier projectile 2 points
Carrier projectiles are those in which the projectile body is used as a vehicle for conveying a payload to the target area.
The projectile body itself plays little or no part in achieving the desired target effects
Carrier shells: Types
List
List the 3 main types of carrier projectile
Then list the 6 other carrier projectiles
Smoke,
Illum,
Conventional anti pers
Sub-projectiles incendiary chemical flare radar echo propaganda
Carrier shells: Conventional anti-pers
List
What are the three conventional anti-pers shell types
Shrapnel
Canister
Flechette
Carrier shells: Methods of operation
List
List the four general types of operation that are used in carrier shells
Bursting
base ejection
noise ejection
base emission
Carrier shells: Burster charges
List
List the 7 function and design points on burster type carrier projectiles
Similar shape to a high explosive projectile
Filled with substances other than HE
Use a Burster to open the projectile to scatter its contents
The Burster contains a high explosive which is initiated by the fuse booster
Can be utilised for both ground and air burst effects depending on the required terminal results
Should range the same as the high explosive projectile
Quicker form of payload delivery than base/nose ejection and base emission.
Carrier shells: base ejecting carrier projectile
List
List the 12(!) function and design points on base ejecting type carrier projectiles
One of the most common designs
The payload is ejected through the base of the projectile, usually during flight
Essential for the projectile to have a cylindrical internal cavity
Must have a weakened base to ensure efficient projection or ejection of the payload
The base is enclosed by a base plug which is pinned
The method of attachment is designed to give strength during firing yet allow easy removal by inside forces when the projectile is needed to operate
The payload is ejected by means of a burster or expelling charge which is initiated by a time fuse
Burster/expelling charges often contain black powder
Pressure build up inside the projectile caused by the deflagration of the burster/expelling charge eject the payload.
The payload will initially tend to follow the trajectory of the projectile and then disperse as appropriate
The flash from the burster/expelling charge also ignite the payload container if necessary
Carrier shells: nose ejecting carrier projectile
List
List the 6 function and design points on nose ejecting type carrier projectiles
Payload is ejected forward
Weakened section towards the nose at the end of the parallel position of the body (shoulder)
The flash output from the fuse functioning passes down a central channel to ignite an expelling charge.
Baffle plate
Expelling charge forces the plate forward and shears the weakened section of the nose
The contents are then pushed forward and outward
Carrier shells: Base emitting carrier shells
List
List the 5 function and design points on base emitting type carrier projectiles
This method of operation is generally met in low velocity weapons such as 2” mortars
The flame from the propellant gases is used to ignite a pyrotechnic delay composition in the bomb body
This burns through and ignites the main filling
Smoke is then emitted from ports at the rear of the bomb
Emission often starts while the bomb is in flight but this depends on the angle of projectile and the time of flight.
HE shell design:
List
6 Factors affecting shell design
Target Effect
Ballistic performance
Strength to withstand firing stresses
Economy in manufacture
User requirements
Safe handling, transportation and storage
HE shell design:
List
What are typical calibre lengths for weapons?
Spin stabilisation – up to 7 calibres
Large calibre shells – 5-6 calibres
HE shell design:
List
What are some forces acting on a projectile, 6 points
Gas pressure
Acceleration
Setback
Heat
Centrifugal
Driving band pressures
Side slap
HE shell design:
List
What are some forces acting on a projectile, 6 points
Gas pressure
Acceleration
Setback
Heat
Centrifugal
Driving band pressures
Side slap
HE shell design:
List
How is nose and base drag reduced? two points each
Nose Drag
Nose drag is the major influence in retarding a shell
Reduced by the shape of the head
Base Drag
Base drag is caused by the region of low pressure
Base drag may be reduced by streamlining (boat-tailing)
Exploders and supp charges:
Define
define an exploder
A charge in the form of a pressed pellet or filled container of secondary high explosive designed to amplify the detonation wave produced by a fuse detonator or magazine to ensure efficient detonation of the main charge.
Exploders and supp charges: Exploder systems
List
What factor of an exploder explosives must be ensured and why
The loading density must be correct
Too low means more sensitive
High density is required to reduce sensitivity and ensure a high level of propogation
Exploders and supp charges: Exploders systems
List
What explosive was historically used, what is typically used now.
What name are exploders usually referred to now
Historically CE has been used but there is now a tendency towards RDX/BWX
COMP A
Usually referred to as supplementary charges. (this is the explosive part of the exploder)
Exploders and supp charges:
List
Define a supp charge
A cylindrical aluminium container, (filled with either TNT or Comp B) which is used to fill the cavity below the fuse in deep cavity projectiles. It is removed when some proximity fuzes are fitted to the projectile.
Exploders and supp charges:
List
List the benefits of modern exlploder systems, being canned CE pellets w/ aluminium casings
Ease of removal.
Setback movement eliminated.
No explosive migration.
Define an exploder system
The components used for transmitting the impulse from the fuze or booster to the HE filling.
