Design Aspects
The FSAPDS
ammunition has been designed as a two-piece separate loading ammunition, capable of:
Being fired from smooth bore T-72 tank gun
Stowage in tank within the existing space
Loading by auto-loader without affecting the rate of fire
Ballistic performance to conform to the existing T-72 sight
graticule pattern
Defeating all NATO targets at a range of 2500 m
Principle of FSAPDS
FSAPDS is a
sub-calibre projectile (penetrator) successfully designed to meet the ballistic
requirement in the gun and at the target. The full calibre shot provides a large base area
for the propellant gas to work against in accelerating the projectile to a high velocity.
The heavy sub-calibre penetrator provides high kinetic energy, concentrated over a small
cross- sectional area. To get maximum penetration at the target, the length- to-diameter
(L/D) ratio of the pene- trator needs to be increased to the maximum extent possible.
Accordingly, this design caters for L/D ratio of about 15, which makes this penetrator
capable of defeating all triple NATO targets at a range of 2500 m. Penetration of the
target depends on the behaviour of the material of both the armour and the projectile and
it is governed by the kinetic energy of the projectile. The greater the kinetic energy of
the projectile and smaller the area over which the energy is applied, the better will be
the penetration.
The
mechanism by which the penetration by this tungsten alloy penetrator at hypervelocity is
effected, includes hydrodynamic deformation, mushrooming, macro- scopic plastic
deformation, erosion, localised plastic deformation, brittle fracture, adiabatic sheer
bending and melting/ thermomechanical interaction. Basically, this ammunition has achieved
superior penetration power due to suitable mechanical properties of the tungsten-based
alloy used for penetrator and its proper shape given to it for better stability to avoid
ricochet at higher angle of impact at the target end
Description of Ammunition
The
complete round consists of two cartridges, an FSAPDS shot with a supplementary charge
attached to it, called the secondary charge (or the front cartridge) and a main powder
charge called the primary charge (or the rear cartridge). The secondary charge consists of
a shot which includes the tungsten alloy penetrator, three-segmented aluminium sabots, a
tail fin for stability in flight, nylon bands, rubber seal, a tracer and a combustible
cylinder with propellant charge. The primary charge consists of a combustible cylinder
with propellant charge, a steel cup which functions as the obturator and an
electromechanical primer screwed on to the steel cup base.
Functioning of FSAPDS
The
combination of HE, HEAT and FSAPDS ammunition, as per the requirement, can be stowed in
the tank bins and loaded into the barrel by an auotmatic loading mechanism. When the round
is loaded and fired from T-72 tank, the shot exits the muzzle and gases and aerodynamic
forces acting on the sabot segments cause it to separate from the sub-projectile. The fin
stabilised sub-projectile will continue to fly on its extremely flat trajectory to the
target. Flight of the sub-projectile can be observed with the help of burning tracer.
Technology Involved
Manufacturing
Technology
FSAPDS
components are sensitive and sophisticated in nature and demand utmost care during their
manufacturing and assembly. The dimensional and weight accuracies in various components
are maintained to very close tolerance limits to achieve optimal overall performance of
the ammunition.
Great care
has been taken in selecting the operation layout for various components and other
manufacturing facilities to minimise the rejection rate. Because of the intricate design
and the need for close tolerance limits, major components are manufactured in combination
with NC/CNC, high productive semiautomatic machines.
By
introducing NC/CNC machines in flexible manufacturing system (FMS) mode, provision has
also been made for machining operation of components for other calibre FSAPDS ammunition.
Automatic online inspection of components has been introduced stagewise to ensure quality
control and to increase productivity.
Powder
Metallurgy
The
technology know-how developed on laboratory scale for the manufacture of high strength,
high density tungsten alloy rods was converted into mass production methods and production
established at HAPP. The heavy alloy rods are made from constituent powders through
sintering process. The homogeneity and density along the entire length of the rod is
maintained through in-built monitoring devices on the heating furnaces and online
inspection at different stages.
Performance
Accuracy <0.3 miles
Penetration Can defeat all NATO targets at a range of 2500m
and beyond
Range
Effective lethal
range up to 3000m
Behaviour Functions satisfactorily at extreme
climatic conditions |
Surface Coating
Two
critical aluminium components are exposed to very high temperature zones during launch. To
withstand the environment, hard anodizing at sub-zero temperature as a surface protective
coating was established for this purpose for the first time in Ordnance Factories. This
also enhances the shelf life of the ammunition against corrosion.
Ultrasonic
Flaw Detection Techniques for High Density Materials
Since the
tungsten alloy manufactured by sintering method has density more than 17 g/cc, the flaw
detection becomes critical. No suitable ultrasonic equipment for detecting the flaw below
0.8 mm crack size was available in the country. It was imported as a tailor-made equipment
and successfully commissioned at HAPP. This unique non-destructive testing method gives
reliability on mass scale for getting the penetrators tested.
Establishment
of Polymer Materials
The
technology for two critical components made out of Nylon 6/6 and silicon rubber were
established with stringent specifications. These are critical items for enhancing the
performance of the ammunition.
Semi-Combustible
Cartrige Case
This
technology, developed on pilot scale, was successfully transfered to the trade for meeting
the bulk requirement of the Army.
Testing
and Evaluation
The testing
and evaluation facilities used during design, development and production stages have been
augmented by high speed cameras, tracking radars and other critical instruments to suit
the bulk production requirements.
Technology Transfer
The
transfer of technology of this ammunition has been completed in record time and production
agencies have been geared up to produce more than 40000 rounds per annum with high
reliability of the ammunition. This product, engineered to stringent production and
quality assurance specifications, has enhanced Army’s self-reliance and fighting
capability. Moreover, the country could save precious foreign exchange to the tune of
around Rs 200 crores per annum.
125
mm FSAPDS ammunition developed by DRDO has enhanced Army's self-reliance and could save
the country foreign exchange of around Rs 20 million per annum.
