TRAINING PROJECT SEMINAR

STUDY OF INTERNAL PRESSURE MEASUREMENTS INSIDE A GUN CHAMBER

PROOF AND EXPERIMENTAL ESTABLISHMENT(PXE),DEFENSE RESEARCH AND DEVELOPMENT ORGANISATION(DRDO),CHANDIPUR,BALASORE

AASIFA ROUNAKREG. ID:10010103

MECHANICAL ENGG DEPT.,VSSUT BURLA

GUIDE: R.K.Gangwar;Scientist D,Weapon Wing

ROLE OF PXE• Evaluation of Weapon Systems

Evaluation of ammunition and weapon platform performance through dynamic

firing and evaluation.

Provide a fully instrumented and calibrated firing range for test & evaluation of

all arms & ammunitions of Indian /Imported origin.

• Dynamic Proof

• Proof & evaluation of ammunition production batches from Ordnance

Factories.

• Conduct design and developmental trials of armament stores, i.e., weapons,

ammunition and their components.

• Technical evaluation of imported weapons and ammunition. Conduct

developmental trials for different armour materials.

• Carry out out-turn proof of weapons, ammunition and their components,

as also armour produced by Ordnance Factories, PSUs and trade firms.

• Depot check proof.

• Investigation firing and failure analysis.

• Analysis of ballistic data and design parameters.

• Undertake projects for design and development of range

instrumentation, as also projects for improvement and modernization of

range techniques and facilities.

To help integrate all fire support assets into combined arm operations

Destroy, neutralize

or suppress the enemy

FIELD ARTILLERYMISSIONS

PARTS

Multiple rocket launchers - Mobile rocket artillery Launcher

Howitzers - capable of high angle fire

Gun howitzers- capable of high or low angle fire with a long barrel

Field guns - capable of long range fire

Mortars - lightweight weapons that fire projectiles at an angle of over 45 degrees to the horizontal

Mountain guns - lightweight weapons that can be moved through difficult terrain

Infantry support guns - directly support infantry units (mostly obsolete)

TYPES

Internal ballistics, a subfield of ballistics, is the study of a projectile's

motion from the time its propellant's igniter is initiated until it exits

the gun barrel.

•Energy is imparted to the bullet in a firearm by the pressure of the gases

produced by the burning gunpowder.

•Chamber pressures in the range of 60,000 PSI are produced.

•PHYSICS OF FIREARMS:Delivering maximum destructive energy to the target

with minimum delivery of energy on the shooter. The momentum delivered to

the target however cannot be any more than that (due to recoil) on the gun-

shooter system.

ON FIRING

pressure curve of a typical cartridge (in this case from the M193 5.56mm cartridge using 846 ball

powder)

TYPES OF PRESSURE MEASURING SYSTEMSCOPPER CRUSHER GAUGE

• The gas pressure is applied via a piston to a calibrated copper crusher.• The amount of deformation of the crusher is used as a measure of the maximum

pressure.

IPGs

• Used for continuous pressure-time recording.• Piezoelectric technology is insensitive to electromagnetic fields and radiation,

enabling measurements under harsh conditions

STRAIN GAUGE

• A strain gauge takes advantage of the physical property of electrical conductance and its dependence on the conductor's geometry.

• Typical input voltages are 5 V or 12 V and typical output readings are in mill volts.

SERBERT’S VELOCIMETER

• Discrete values of the projectile’s in-bore velocity can be obtained by mechanical or optical switches.

• Most of these techniques imply the drilling of holes in the barrel. Non-destructive and continuous in-bore measurement techniques for determining the projectile’s velocity are generally based upon the Doppler effect.

WHY IS PRESSURE MEASUREMENT IMPORTANT?

1. For testing the barrel strength to withstand bends and cracks on impact of known intensity and duration.

P1- 15% more than the working pressureP2-20% more than the working pressure

2. For testing propellant charge.

3. For testing of internal bore and driving band accuracy.

4. For estimating range and time of flight.

5. To check for leakage and other technical glitches.

1.COPPER CRUSHER GAUGE

MK 8 gauge

MK 9 gauge

1. Calibrated by a special crusher gun and plotted on a tarage table.

2. Crusher balls material:Oxygen-free high conductivity copper.>99.95% Cu, <0.05% Oxygen, <0.003% Silver.

3. Impact of piston weight in gauge falls on the crusher balls.

4. Un-impacted by duration of pressure pulses.

2. ELECTRONIC SENSOR GAUGE1. Inbuilt battery triggered by force of inertia.

2. Piezoelectric crystals-PZT(Lead zirconate titanate, tourmaline, rochelle

salt.

3. Gives a dynamic P-T curve for all time instants.

4. Adopted low power technology and miniaturization with storage testing technology upto 4KB.

Piezoelectric pressure

transducer

Charge amplifi-

erADC

RAMContro-

llerCircuit

Oscilla-tor

Interfa-ce cct.

Computer Processing and display

3. STRAIN GAUGE

1. Comprises of insulate flexible backing

supporting a metal foil pattern.

2. Deformation causes electrical resistance

to change which is measured across the

Wheatstone bridge.

3. PRINCIPLE:

Electrical conductance is dependent on

conductor's geometry.

FAULTS• Zero Offset - If the impedance of the four gauge arms are not

exactly the same after bonding the gauge to the force collector.

• Temperature coefficient of Gauge Factor (TCGF) - The change of sensitivity of the device to strain with change in temperature.

• Zero Shift with temperature – Caused by anomalies in the force collector.

• Linearity - This is an error whereby the sensitivity changes across the pressure range.

• Hysteresis - This is an error of return to zero after pressure excursion.

• Repeatability - This error is sometimes tied-in with hysteresis but is across the pressure range.

“One could spend a lifetime studying pressure measurement and still be

surprised on a regular basis by unexplained exceptions to the generally

accepted rules.”

-Terry Hart

• If you measure 100 rounds of exactly the same load, in

exactly the same gun, with exactly the same test

equipment the measurements will typically vary plus or

minus 5-10% or more from round to round.

•No method of measuring chamber pressure is 100%

accurate.

•For reasons not yet understood there are numerous

exceptions for individual cartridges.

•This is not yet a perfected science and research on this

field is still going on.

CONCLUSION

THANK YOUQUERIES?