Electromagnetic Railgun

Electromagnetic Railgun is an emerging technology. A railgun follows basic principle of Faraday’s law of electromagnetic induction and homopolar motor, typically invent as a weapon, which uses electromagnetic force to launch & accelerates high velocity projectiles. The projectile usually does not contain explosives. The EM Rail gun is an entirely electrically powered electromagnetic projectile launcher. It is an electrical gun that uses pairs of metallic rails to accelerate a conductive projectile. Conventional launchers use high pressure inside the barrel to accelerate a projectile, but due to expansion, limits of gas achieving high velocity becomes a constraint. Because of these restrictions, projectiles launched from a conventional gun can reach a velocity up to 1300m/s. EM Railgun, velocity of 20,000 - 50,000m/s can be achieved theoretically, and 6000 – 7000m/s practically. Apart from its application as a weapon its mechanism can be used to launch space ship or space rockets.

Objective:

Electromagnetic Railgun as its name show works on two rails and it is completely electrically powered projectile launcher. Other conventional launchers required many mechanical works involved and many combustions of gases to launch a projectile. These mechanical work and combustion of gases cause many limitations in increasing the conventional launcher projectile speed and range.

While Electromagnetic Railgun is completely electrically powered projectile launcher required only electrical power to launch a projectile. So, it is easy to achieve Mach 5 to Mach 7 Speed with electromagnetic Railgun. With its speed its range is also multiple times greater than conventional projectile launcher such as EM railgun is much more effective than Pakistan existing ABABEEL & HATF 1 & 2 missile system in terms of speed and range.

Normally, a conventional launcher is used to target area under 100km – 140km, but to target area more than 140km, missiles are used which are more costly because they required proper engine mechanism for flight. So, to overcome this issue the researchers are working on EM railgun which provides speed of Mach 5 to Mach 7 and can hit the target over long distance up to 300km.

Objective of EM railgun is also to achieve high rate of firing, conventional projectile launcher has relatively less fire rate than EM Railgun.

On aircraft carriers pressurized steam is used to quickly accelerate aircraft so they can take off in short distances. These methods all have their limitations. So Electromagnetic Railgun is a remedy for it such problems.

Electromagnetic Railgun is also very beneficial for launching space ships / rockets, in launching space shuttles as currently highly expensive propellent is used, use of this propellent is a constraint to achieve very high speed in short period of time but Electromagnetic Railgun does not have any such limitation and can effectively launch such space shuttles with very high initial velocity.

Socio-economic Benefits:

Modern methods of accelerating persons, projectiles or payloads typically use exothermic reactions fuelled by propellants or pressurized non-combustible gases. For example, firearms use fast burning powders which create tremendous pressures due to expanding gases. An increase in desired velocity means carrying more fuel which causes problems of requiring more weight and having to deal with more dangerous materials. For practically all applications the maximum achievable velocity is bounded. For example, in the case of launch vehicles adding more stages does not increase the final velocity proportionally; instead, the maximum velocity achieved by adding more stages quickly reaches a limit.

In firearms the maximum velocity is bounded by the efficiency of the powders, the amount of powder used, the geometry of the barrel, and the aerodynamics and integrity of the projectile. More generally, velocities are bounded by the speed of sound of the expanding or propelling gas; the projectile rides the pressure differential caused by pressure wave of the expanding gas which is moving at its speed of sound.

There is a need for accelerating matter quicker and to greater velocities which these conventional methods cannot achieve. Electromagnetic railguns which propel projectiles with large currents seem to fit the bill. Since there is no expanding gas propelling the projectile, but rather current, the velocity is no longer bounded by a certain speed of sound of a gas.

Normally, a conventional launcher is used to target area under 100km – 140km, but to target area more than 140km, missiles are used which are more costly because they required proper engine mechanism for flight. So, to overcome this issue the researchers are working on EM railgun which provides speed of Mach 5 to Mach 7 and can hit the target over long distance up to 300km.

Electromagnetic Railgun is completely electrically powered projectile launcher required only electrical power to launch a projectile. So, it is easy to achieve Mach 5 to Mach 7 Speed with electromagnetic Railgun.

Using Concepts of EM Railgun, we can also make more efficient Electric Trains

Methodology:

Our Project implementation is divided into two phases:

1. Mathematical Calculation
2. Practical implementation

Mathematical calculation:

In first phase, completed a literature review and, on that basis, completed mathematical analysis.

In which we analysis on following questions:

• How much minimum magnetic Field required to launch a certain specification (mass, resistivity etc) of projectile?
• How much minimum current and voltage required to launch a certain specification (mass, resistivity etc) of projectile?
• Which specification capacitors do we need for our capacitor bank?

To get required current we use HV electrolytic capacitors which provide required current in short period of time, therefore done mathematical analysis on how much capacitor value required.

Practical Implementation:

For second phase that is practical implementation, we design a capacitor bank of HV electrolytic capacitors which is used to supply a required current instantaneously. Above that capacitor there is the rails setup which provide mechanism to launch our projectile. 

On rails we used heavy resistors to discharge our capacitors in case when our EM railgun is in not working. We are also considering to install capacitor voltage monitoring system to control or monitor the amount voltage charged in capacitor while charging. 

Working

Electromagnetic Railgun consists of two parallel metallic rails which are distant from each other and there is air gap between them. To provide high current there is also a current source. In this project capacitor bank is used to provide large amount of current in short instance of time. Both rails connect with capacitor bank one from positive and from ground. When projectile came in contact with both rails and filled air gap, current starts flowing from it that results magnetic force to produce in rails due to the Lorentz Force, the projectile is pushed out of the barrel with high velocity.

As the bullet move in barrel the density of magnetic field increases which causes the projectile to move with high velocity and covers long distance.

Outcome:

Outcomes of EM Railgun are as follows:

As EM Railgun has high speed and long target engagement capability, EM Railgun also have rapid firing rate. So, it can be used in following sectors:

1. EM Railgun can be used in NAVY warship.
2. EM Railgun can be used in NAVY Submarines.
3. EM Railgun mechanism used in ARMY tanks. 
4. EM Railgun can be used for artillery.
5. EM Railgun principle can be used in Aircraft Carrier to launch Aircraft.
6. EM Railgun can be used in Anti-Missile Defence System because its engagement time is less and it has Mach 5 – Mach 7 Speed.
7. Apart from all its application in Defence Sector it can be used in launching Space Rockets / Space ships.