railgun’s ballistics | massacritica

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Tags: Boeing's Phantom Works, cannons, current electric motor, electrically powered electromagnetic projectile, electromagnetic effects, General Atomics Blitzer system, Globalsecurity.org, kinetic energy, kinetic impact, launch assist of spacecraft, Mach 5, muzzle energies, muzzle velocities, naval guns, naval weapons platform, railgun, railgun's ballistics, space launches, Weaponry

Rail gun

Pubblicato il 27 ottobre 2015 by redazione

A railgun is an electrically powered electromagnetic projectile launcher based on similar principles to a direct current electric motor. A railgun comprises of a pair of parallel conducting rails, along which a sliding armature is accelerated by the electromagnetic effects of a current that flows down one rail, into the armature and then back along the other rail. The railgun requires a pulsed direct current power supply.

In terms of target effects, increased terminal velocities can allow the use of kinetic energy rounds as replacements for explosive shells. Therefore, typical military railgun designs aim for muzzle velocities in the range of 7200–12600 Km/h with muzzle energies of 5–50 MJ (mega joule). For comparison, 50MJ is equivalent to the kinetic energy of a school bus weighing 5000 Kgs, travelling at 509 km/h. A typical power consumption would be around the order of 5 mega Amperes for a few millisecond generating a magnetic field of around 10 Tesla.

Applications

Launch or launch assist of spacecraft

For space launches from Earth, relatively short acceleration distances (less than a few km) would require very strong acceleration forces. Other designs include a longer helical (spiral) track, or a large ring design whereby a space vehicle would circle the ring numerous times, gradually gaining speed, before being released into a launch corridor leading skyward.

In 2003, there was a plan to turn this idea into a realized technology. The accelerations involved are significantly stronger than human beings can handle. This system would be used only to launch sturdy materials, such as food, water, and fuel. The system would cost €475/kg, compared with the present system which costs around €9050/kg. This system would launch 500 tons per year, spread over approximately 2000 launches per year. Payload per launch in these conditions is over 400 kg.

Weaponry

Railguns are being researched as weapons with projectiles that do not contain explosives or propellants, but are given extremely high velocities: 9000 Km/h (approximately Mach 7 at sea level) or higher, comparing this to a M16 rifle, it has a muzzle speed of 3350 Km/h, which because of its much greater mass generated a muzzle energy of 360 MJ and a downrange kinetic impact of energy of over 160 MJ. The speed, cost, and numerical advantages of railgun systems may allow them to replace several different systems in the current layered defense approach

Railguns by firing smaller projectiles at extremely high velocities can yield kinetic energy impacts equal or superior to the destructive energy of 5 inch naval guns, but with much greater range. This decreases ammunition size and weight, allowing more ammunition to be carried and eliminating the hazards of carrying explosives or propellants in a tank or naval weapons platform. Also, by firing at greater velocities, railguns have greater range, less time to target, and at shorter ranges less wind drift, bypassing the physical limitations of conventional firearms. Current railgun technologies necessitate a long and heavy barrel, but a railgun’s ballistics far outperform conventional cannons of equal barrel lengths. Railguns can also deliver area of effect damage by detonating a bursting charge in the projectile which unleashes a swarm of smaller projectiles over a large area.

The first weaponized railgun planned for production, the General Atomics Blitzer system, began full system testing in September 2010. The weapon launches a sabot round designed by Boeing’s Phantom Works at approximately Mach 5. During one of the tests, the projectile was able to travel an additional 7 kilometers downrange after penetrating a 3.2 mm thick steel plate. The company hopes to have an integrated demo of the system by 2016 followed by production by 2019, pending funding. Thus far, the project is self-funded.

Issues of Railgun

Durability: To date railgun demonstrations, while impressive, have not demonstrated an ability to fire multiple full power shots from the same set of rails. As noted in an article by Globalsecurity.org railguns should be able to fire 6 rounds per minute with a rail life of about 3000 rounds. Given launch acceleration of up to 60,000 G’s, massive pressures and mega amperes of current, railgun rails are quickly destroyed and getting to the endurance to fire hundreds of full-power rounds, to say nothing of thousands of rounds, could require breakthroughs in materials science that cannot be scheduled and could be decades in coming.

Until the capability of firing at least hundreds of rounds of full power shots from the same set of rails is demonstrated, railguns as a field weapon remains an interesting idea with a lot of potential.

And the same thing applies to the space scenario too.

by Cinthoiba Ngaseppam

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