Railguns

RAIL GUNS

Amar Nath 10104EN052

B.Tech Part IV

Critic: Saurabh Pathak

OVERVIEW What is a rail gun? History Components Working Comparison Benefits Problems Applications

WHAT IS A RAIL GUN? Simply, a rail gun is a gun that launches

projectiles using magnetic fields and current instead of consumed fuel.

Rail gun theory is based on the Lorenz force phenomenon.

When a wire carrying an electrical current is placed in a magnetic field, each of the moving charges, which comprise the current, experiences the Lorentz force, and together they can create a macroscopic force on the wire, which is expressed as

HISTORY

In 1944, during World War II,  using batteries as it’s power source, Joachim Hänsler created the first working rail gun, which was able to propel a 10 g mass to speeds of about 1km/s.

1964-MB Associates used a 28kJ Capacitor to accelerate 5 and 31 mg nylon cubes with a plasma arc as the armature with speeds of 5-6 km/s.

COMPONENTSTwo Rails Power SupplyArmature Firing CircuitryShell Breach

THE RAILS Materials:The best rail material will depend on specific design. Important characteristics of a good rail material are:

=>High conductivity.=>High strength.=>Resistance to corrosion.=>High melting point. =>Availability.=>And finally price.

Shape It depends on the contact patch between

rail and shell. Dependent on shape and type of shell.The shape and size of shell determine the

speeds that can be achieved by it.

THE RAILS

ARMATURE The armature, which drives the shell, closes

the electromagnetic loop between the rails and is forced along their length at extremely high speed.

Different types:– Solid piece of conductive metal (Conductive sabot

)– Metallic plasma for very high velocity shots

THE SABOT (PROPOSED DESIGN)

Benefits

optimum current carrying capacity and heat dissipation.

projectile itself may be designed for more stability and less drag.

Speeds up to 10mile/s.

THE POWER SUPPLY AND FIRING CIRCUIT COMPONENTS

Rail guns require tremendous currents to fire a projectile at great speed. Typically, the current used in rail guns is in the millions of amperes, while the duration will be less than 10ms. Maintaining a high current as long as possible increases the amount of energy input to the projectile. Thus following components are required

AC Source Transformers Capacitors Inductors Switches

COMPARISON

Rail Gun Range of 200 miles and

above. Speed: Hypersonic. About

7-8 Mach . No such speed limit.

Normal Guns Range of 20 miles Speed: Subsonic. Less than

Mach 1. Explosives have limit up to

which they can provide speed to the shell.

The capabilities of Rail gun are even greater than that of cruise missiles like TomaHawk and BrahMos.

BENEFITS Extremely Fast

It hold the record for fastest object accelerated of a significant mass, for the 16000m/s firing of a 0.1 gram object

Can propel large masses 32Megajoule gun fires a

1.6kilogram projectile at

3300m/s Extremely Accurate

PROBLEMSRepulsion:Each rail in a rail gun carries a current anti-parallel to the current in the other rail. The laws of physics show that two anti-parallel currents repel each other. Since the currents in a rail gun are large the repulsion between the two rails is very large. Rail guns thus have the tendency to break after a few uses, which makes them not very cost effective.

High Temperatures:Because the rails in a rail gun are not super conductors they have a resistance. Since the current that must go into a rail gun is so massive the amount of heat that is produced this way is very high and thus may fuse the projectile to the rails which will either render the rail gun useless or slow down the acceleration of the projectile. A solution to this problem is to make the rails in a rail gun super conductors.

PROBLEMS

APPLICATIONS Military Applications

TanksBattleshipsDestroying Asteroids

and meteoritesDestroying planes (Anti

aircraft warfare).

Peaceful ApplicationsElectric Trains: Using magnetic levitation and

linear motors for building fast locos.

Space launch: In place of shell rockets, satellites can be launched from appropriate carriers.

Nuclear Fusion: Rail guns may be able to trigger fusion by firing energetic plasma from multiple directions.

APPLICATIONS

REFERENCES http://en.wikipedia.org/wiki/Railgun http://members.tm.net/lapointe/EMGuns.html http://home.insightbb.com/~

jmengel4/rail/rail-rails.html http://www.powerlabs.org/railgun.htm http://www.rit.edu/~dih0658/apps.html http://www.dstl.gov.uk/pr/science_spot/off_the_rails

3.htm http://members.tm.net/lapointe/EMGuns.html