What is Railgun: Definition and 48 Discussions

A railgun is a linear motor device, typically designed as a weapon, that uses electromagnetic force to launch high velocity projectiles. The projectile normally does not contain explosives, instead relying on the projectile's high speed, mass, and kinetic energy to inflict damage. The railgun uses a pair of parallel conductors (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. It is based on principles similar to those of the homopolar motor.As of 2020, railguns have been researched as weapons utilising electromagnetic forces to impart a very high kinetic energy to a projectile (e.g. APFSDS) rather than using conventional propellants. While explosive-powered military guns cannot readily achieve a muzzle velocity of more than ≈2 km/s, railguns can readily exceed 3 km/s. For a similar projectile, the range of railguns may exceed that of conventional guns. The destructive force of a projectile depends on its kinetic energy and mass at the point of impact and due to the potentially high velocity of a railgun-launched projectile, their destructive force may be much greater than conventionally launched projectiles of the same size. The absence of explosive propellants or warheads to store and handle, as well as the low cost of projectiles compared to conventional weaponry, come as additional advantages.Notwithstanding the above advantages, railguns are still very much at the research stage after decades of R&D, and it remains to be seen whether or not they will ever be deployed as practical military weapons. Any trade-off analysis between electromagnetic (EM) propulsion systems and chemical propellants for weapons applications must also factor in its durability, availability and economics, as well as the novelty, bulkiness, high energy demand and complexity of the pulsed power supplies that are needed for electromagnetic launcher systems.

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  1. G

    I Railgun: Significant magnetic field where projectile is?

    Hi. Very simplified schematics of railguns all look like this: I have trouble properly understanding this. So apparently there is still a significant magnetic field where the projectile is, even though that's where the current stops flowing through the rails? Of course the magnetic field...
  2. A

    I Power equation in railgun operation

    In a capacitor discharge through a plain resistor, the capacitor power supplied at any instant is VI; the power dissipated in the resistor is I²R. So VI = I²R. Consider a railgun operated with a capacitor bank. At any instant of capacitor discharge, the power supplied is VI. The total power...
  3. M

    Would a portable railgun make a lot of noise?

    I'm using a portable rail gun in my novel - details in the paragraph below - but I wondered whether it would be as quiet as I'm suggesting. The slugs are coming out at Mach 5, which is a touch under 6,200 kmh. Obviously, they're breaking the sound barrier in the barrel, so would a tiny (or big)...
  4. A

    I'm Confused about Buoyancy (Anime: A Certain Scientific Railgun)

    well I was watching the Third Season, and I was Confused, there's an esper her ability name is Float Dial it is an ability to control buoyancy. at first I understand, that it controls fluids thus able to slide on water walk on walker. but how the does she able to lift the heavy concrete and...
  5. Auto-Didact

    News 'Chinese Navy ship seen carrying railgun'

    China says its navy is taking the lead in game-changing electromagnetic railguns Rest of the article is on the site. The news is available on multiple news outlets, including pictures on Twitter. I recall the US Navy was developing a railgun a few years ago, while Russia was still in the R&D...
  6. PlanetGazer8350

    Calculate iron container acceleration in railgun system on the Moon

    Having a cylindrical iron container with wall thickness of 20 cm, and a total weight of 500 tons when filled with its cargo, how would you be able to calculate its required voltage and current input in a vertical railgun system (relative to the Moon's surface), with an exit acceleration of...
  7. Z

    I Railgun and energy considerations

    Hi forum Can anyone explain where the energy is ... Consider a railigun, a voltage is put across the two parallel rails, a current starts building up, whille some energy is stored in the magnetic field inside the current loop. The energy stored in the magnetic field is: U=0.5*L*I^2 I being...
  8. E

    I Railgun: Problems with reality check

    So I was doing some calculations last night on railguns for fun, and I got some very surprising results which seams like they must be wrong. The calculations are simple and I must have overlooked something. So we all know that F = B * I * L when all are orthogonal, a capacitor discharge is I =...
  9. M

    Magnetic field of a finite wire increasing with distance?

    I am computing magnetic field around a thick conductor to do railgun force modeling. I am currently re-examining my magnetic field computation, and I have found some confusing results stemming from a fairly simple use of the Biot-Savart Law. The main issue is that the more nuanced application of...
  10. M

    Magnetic Field Computation from Thick Rectangular Conductor

    Hello, and thanks in advance for taking a look at my question. Generally, I am trying to make a railgun force model. Since railguns depend on the magnetic field created around the rails (and the resulting Lorentz force) I need to model the magnetic field created by the current that flows...
  11. B

    Research for Science Fiction Story

    I'm researching a topic for a sci-fi story. One of the elements is a "space glove", basically a network of nets that "catch" rods of ballistic projectiles launched from the peaks of mountains by railgun. Any comments or insights would be helpful. Here is a data dump of my scribblings on the...
  12. BoeingJet

    Can a Railgun-Powered Ramjet Solve the Challenges of High-Speed Travel?

    Recently, I designed (in my head) a Hypervelocity Passenger Vehicle (just a cool name for really high speed transports). I immediately ran into engine design problems ( I like designing everything stand-alone), since regular jet engines can't get to Mach 8.8 without burning up into flames, and...
  13. A

    Top Speed of a Railgun: Lorentz Force

    Ive asked this question before but i wrote it in a very confusing manner so ill do it again but in more qualitative terms: The "classical railgun" i first learned about (mag field is produced by a permanent magnet) has a top speed because as the slug accelerates, the time derivative of mag flux...
  14. A

    B Beating the physics of a railgun

    Ive recently been thinking of rail guns. When i first learned about this type of motor ( we use to call it the linear motor), i read that the projectile would eventually reach a top speed because of faraday's law creating a counter current. However, what if the magnetic field ( the one that is...
  15. Alexander Stroborg

    Can a 400V 2200µF capacitor propel 0.5g through a rail gun?

    I am planning to conduct an academic experiment involving an electromagnetic projectile. I originally planned to build a rail gun powered by a 400V 2200µF capacitor, I've read a lot of discussions that say rail guns require a tremendous amount of current. Is this capacitor sufficient to propel...
  16. M

    Magnetic Field at any Point Around a Finite Straight Wire

    Hello, First of all, this question does stem from graduate work, but it seems far too simple to tag "advanced". I am looking to write some code to simulate the force from a railgun. The first step in doing this (from a tutorial I found) is to find the magnetic field at any point within the...
  17. xpell

    Hypervelocity cannons: Why not centrifugal?

    After reading a lot about railguns, light gas guns and other approaches to build an hypervelocity/hypersonic cannon, I wonder why the "centrifugal cannon" option hasn't been more thoroughly explored by any military power in the world. Yes, I know the old versions had a precision problem and were...
  18. D

    I Do Railguns Recoil? Understanding the Forces Responsible for Railgun Recoil

    Do railguns recoil? and if they do, what force is responsible? When I looked at a basic railgun schematic I noticed that the magnetic field from the rails causes the projectile to accelerate forward and I also noticed that the magnetic field from the projectile should push on the rails outward...
  19. C

    Railgun and the laws of physics

    I just made a rail gun using two ring stand poles, a steel ball, and a car battery. Maximum velocity is about 5 cm/sec. What is strange is that it is shooting the wrong way. Defying the laws of physics and right hand rule. Any ideas ?
  20. jlefevre76

    Understanding the Physics of a Coilgun: A Beginner's Guide

    Hey, I've seen a few posts on this without any responses I really thought helped (at least help answer my question). So, I was hoping somebody on the forums here could help walk me through the basic physics of a coilgun. Basically, how could you characterize the magnetic field inside the...
  21. W

    Viable Railgun Setup? (ping pong balls)

    Hello, I'm working on a personal project that requires a very precise, but not very powerful, ping pong ball launcher. Would it be possible to coat a ball in metallic conductive paint, and then fire it from two rails like a railgun? Would I still get a constant net force in the correct...
  22. P

    Coilgun with car audio capacitors

    Hi guys, I'm new to this forum and I just started working on my first coilgun. I've watched several tutorials on how to build a coilgun but all the capacitors they use in the coilguns are electrolytic capacitors. The capacitors don't deliver as much energy as the car audio capacitors. I'm...
  23. K

    Simple Solution to Railgun Power Requirement?

    Old navy guns had shells and magazines that contained many [dangerous] shells below the turrets. With the new 1000+ Farad Capacitors on the market, would it not be possible to have "Capacitor Shells" that are obviously charged on land/factory and then stored in a magazine? Using this method...
  24. N

    A website which shows the ballistic designs concerning railgun ammunition?

    I'm really curious as to what problems would be fundamental to solve when trying to make an efficient projectile fit for speeds produced by a electromagnetic railgun. Firing something that fast into the atmosphere has to be problematic and I'm sure the solution to making the most accurate and...
  25. S

    Powering a Railgun: Generating High Currents & Calculating Velocity

    For fun I wanted to make a railgun, but I am having trouble figuring out how to generate a high current. I have a 400F capacitor (only one, but it is suitable for my purposes). It is rated at 2.7V So the amount of energy it can store is 1458J, so it should be able to run the gun for 1/29 of a...
  26. E

    Force on projectile along rails (Railgun)

    Homework Statement see attachment Projectile P sits between two wide rails of circular cross section; a source of current sends current through the rails and through the (conducting) projectile... Homework Equations F=μ0Liaib/2∏d The Attempt at a Solution Direction is away from...
  27. B

    Railgun Plasma Plume: What Causes it & How Long Does it Last?

    Hi, I've seen a video of the US navy test firing a rail gun and in the video there is a plasma plume that follows the projectile. I am unsure of what exactly is causing the plasma plume... specifically: Is it the electrical energy passing through the rails that ignites the air and...
  28. F

    Railgun Math Simulator: Build Your Own | 400km/h Launch Projectile

    Hey all Im a second year engineering student bored as hell in the second week of a 3 month vacation. So i decided to try and build a small railgun capable of launching a projectile(20-40g) to about 400km/h. Attached is a excel file. It is a sort of simulation. Cells in Blue must be typed...
  29. F

    2nd year Eng.student trying to build a railgun. Verify or modify please

    Hey all Im trying to build a small railgun capable of launching a projectile(20-40g) to about 400km/h. Attached is a excel file. It is a sort of simulation. Cells in red must get values from the table. Cells in Blue must be typed in by user. Cells in Green list the Current/Mass needed...
  30. P

    Electromagnetic Railgun - calculations

    Homework Statement Electromagnetic Railgun consists of two parallel, distant from the horizontal, very long rails, after which moves perpendicular to the rails, linking them to the metal bar of mass m. The rails are in a vertical magnetic field intensity B. What is the speed limit the...
  31. C

    Model Railgun Project - Don't have a grasp of the physics

    My hypothesis is that increasing rail length will increase the distance a projectile travels, ( which is true) unfortunately I can't quite make sense of physics behind railguns to understand how to prove the hypothesis mathematically. Thank you for your time.
  32. E

    Somebody explain railgun mechanism

    i am confused about the railguns electro-magnetic action please somebody explain if possible.
  33. C

    Can you use a Railgun to blast objects into orbit or reduce fuel costs?

    This was an idea I had when when learning about ramjets. I was wondering if you could use a specially designed rail gun to launch a probe or satelitte ,at a very high velocity vertically upwards and then when the object is decelarating at 9.8 m/s due to gravity use a small rocket propulsion...
  34. W

    Exploring the Use of Solenoids in Railgun Technology: Pros and Cons Revealed

    I haven't seen any discussion or any mention what so ever of this before so excuse me if it's that's because it's a crazy idea. What would be the pros and cons of using solenoids as the rails and projectile of a railgun? Would the stronger magnetic field of the solenoids allow a stronger force...
  35. Z

    Liquid non metal conductor for railgun

    Hey all! I've return back to my year 12 assignment, the railgun. I got a working model back then, but unfortunately didn't write up a good report. I have the videos on youtube if anyone is interested. The reason for the conductive liquids is because I want to tackle the arcing issue. I...
  36. N

    Constructing a Railgun: My Cousin's Science Fair Project

    My cousin is thinking about entering a science fair. Originally, we were going to build a small RC robot from scratch. Then he heard about rail guns on tv. You can guess which won. I have a light university background in physics (graduated in 09), but electronics and electromagnetism were not...
  37. I

    Constructing a Large Railgun: Seeking Input

    Just recently started toying around with this idea. and was looking for some good input from anyone more experienced in this area. I am currently working on a much smaller railgun but I plan on working on this larger one. I am working with some others on this project I am more of the...
  38. B

    High School Science Fair Railgun

    Hello, I posted a thread over a month ago asking some basic questions on railguns for my high school science fair project. Since then, I've built a working railgun that fires both cyndrilical and square projectiles. Unfortunately those projectiles consist of compressed aluminum foil, so it...
  39. A

    Railgun Project | Current Question

    Hello, as stated I'm working on a railgun. At this point, I'm in the design phase. I'm currently trying optimize the performance of the gun within the constraint of my resources. As you may or may not know, a railgun consists of two rails short-circuited by a conductive projectile which is...
  40. D

    100% homemade railgun - capacitor question first

    Hello all! I just registered on physics forums and already have many questions! First of all (lets start with just one) my friend and i are attempting to build a homemade railgun. We are tying to make it completely by ourselves - nothing bought besides the materials needed. Since massive...
  41. S

    Electromagnetic Railgun Blasts Off

    Last week at the Naval Surface Warfare Center, in Dahlgren, VA, a seven-pound bullet emerged from a truck-sized contraption at seven times the speed of sound and sent a visible shockwave through the air before crashing into a metal bunker filled with sand. With 10.6 megajoules of kinetic energy...
  42. H

    Building a Magnetic Railgun - Questions & Answers

    Hey everyone I've been wanting to create a magnetic railgun for some time. I have a few questions though. 1. What equations can i use to calculate how fast the "projectile" are moving? 2. Why do the magnets respond like this when electricity flows?? Thanks!
  43. M

    Can I Build a Functional Railgun at Home?

    I've actually been wanting to build one of these. For those of you who don't know how they work, pretty much all it is is that you have a power source, two rails for current to go through (hence the name railgun), and then you have a projectile that is conductive. The current creates a magnetic...
  44. B

    In a railgun the lorentz force causes an object to be propelled

    In a railgun the lorentz force causes an object to be propelled in a direction because of an electromagnetic force caused by running a current through the "rails". How come you can use aluminium or another such non-magnetic metal as both rails and armature? Surely only a magentic metal would work?
  45. K

    Building a battery operated railgun

    can it be done? I am not engineer or anything and i was just wondering if it would be possible to build a railgun using batteries as the power source. my idea is to have around 25 electromagnets on two rails with an aluminum tube in the middle which houses the projectile. then each...
  46. N

    Learn How to Construct a High-Performance Electromagnetic Railgun

    I have decided to make an electromagnetic rail gun,in such a way that three of them are ligned with each other and connected centrally,my problem is that how do I make them rotate at a fixed speed.
  47. M

    Calculating Railgun Force: iBdx

    Hi all. I've been trying to nut out an expression for the force on the projectile ( i hope you have an understanding of the basic structure of a railgun, i don't want to draw it) Anyway, i is known, w is the rail seperation, and R is the circular rail's radius. F(x) = i B(x) dx...
  48. F

    What is the principle behind my homemade railgun?

    I have made an small application of a railgun. It looks simple but I don't get its principle involved here. On a cardboard, two strips of aluminum foils are pasted qith an equal distance apart from each other, resembling a train's path. A pair of alligator clips, both ends have 'head', in...
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