How to Make a RAILGUN!




Posted in PlayOffbeat

Introduction: How to Make a RAILGUN!

Warning: if you screw up with this you could electricute yourself.

Step 1: Materials

For this you will need;

4 or 5 Disposable flash cameras (I went to a camera store and asked them for some and they took a big box with about a hundred in it, they sold them to me at ten cents a camera, I only got ten)
aluminum foil
small switch
big switch
aluminum or steel rails
6 nuts and bolts
wire hanger


soldering iron
duct tape
wire strippers
wire cutters

Step 2: Prepare the Cameras

break open the casing on 4 or 5 cameras
take out the circuit board
take out the capacitors from all but one of them (you might want to take out the flashbulbs too they look cool when you put several thousand volts through them)
remove the swich thing and solder two wires in its place

Step 3: The Circuit

solder the small switch to the two wires you made in the last step
solder the extra capacitors onto the current on (remember to keep the positive and negative sides together)
solder two long wires to the capacitors
solder the big switch onto the positive wire

Step 4: The Rails

make two aluminum or steel rails about 1/2in by 5in (make sure one long side of each rail is perfectly straight)
cut two pices of plexiglass about 1.5in by 4.5in
make a small gap between the rails that is perfectly straight (I used a wire hanger as a divider)
sandwitch it beween the two pieces of plexiglass and clamp it
drill six holes for the bolts
put the bolts in and screw the nuts on tight

Step 5: Set It Up

clip the positive wire on to the right rail and the negative wire on to the left rail with alligator clips
ball up a small piece of aluminum foil and jam it into the middle of the rails
put a battery into the battery thing

Step 6: Fire!

press the small button to charge up the capacitor bank
when the led blinks you can press the big button and fire it
after you're done use a srewdriver to trigger the capacitors a few times before touching it



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    Can I use a Full cylinder of copper


    Can you make this more powerful?

    This is a cool article and I intend to try this with my kids. Please keep up this good work!!! The engineering presented is pretty cool and clever. I have a PhD in experimental physics and have taught physics at the college level. I currently work for a medical equipment manufacturing company and also run a consulting firm that operates in the bioengineering/physics arena. I feel somewhat qualified to comment. Some of the physics, conversions, and calculations in the comments below are erroneous and wrong. Even some that are correct, are out of context and not applicable to the discussion at hand. Quantities such as mass, energy, power, charge, current, etc. are not in general equitable and when they are equitable, it is only under very specific circumstances.

    So you don't need anything to jump start you projectile, I know larger ones use compressed air or springs to avoid welding the projectile to the rails. Also does yours throw cool sparks and stuff, maybe even plasma?

    17 replies

    uhm... Yeah, for a railgun to have enough force to create plasma, it would need several megajoules of energy (if you saw the railgun from DARPA or the US Navy, that one shot took so much energy that it could've been used to power a city for a year).

    To release sparks, a railgun doesn't have to be THAT powerful, but it still requires a fairly large amount of energy. In short, THIS railgun can't be used to kill people or do any heavy damage.

    the biggest railgun (navy) was 33 megajoules or 30000000 joules, or a little over 12 horsepower, I see what you mean, but using a 12 hp engine to charge batteries for one hour couldn't power my house for a year.

    Yeah, thats just wrong. Joules are a unit of energy. Horsepower is a measure of power.

    but power over time is energy right.
    I just found all of this information,
    Watt x Time = Joules This is 8948 time 3600 secconds = 32,212,800 joules which is a pretty good conversion for the one minute I put in.
    Power x Time = Work (energy)

    Joules/distance = Newtons
    Work/distance = Force

    So you can convert power to energy, its just a little more complicated than most conversions.

    Look, you cant just assume time. And the first guy was wrong as a city uses about 2 Gigawatts each year.

    But charging and equations are not linear which you are assuming. By your logic you can convert Joules into cubic meters

    No, I am saying 33 gigajoules is equivalent to 12hp over 1hour. Which it is. I just converted the hp to watts, which is perfectly fine, then I plugged in the proper time which is in secconds, one hour = 3600 secconds. 12hp is very roughly rounded, and the concluded answer was extremely comparable. If I directly converted 12hp over to electrical watts with no loss of energy I would still only get roughly 9kw which would be enough energy if stored to run my house which consumes 3kwh for roughly 3 hours. Its a bunch of math, but it is well reasoned. I know it is difficult to understand converting between these to things.

    Joules are a measure of energy (energy is defined as the ability to do work)
    Work is power * time and is measured as an SI unit of joules
    Power is the rate at which work is performed or energy is converted
    Time is, well you know what time is

    By looking closely at these properties you can conclude that power over time is work or hp over one hour is joules

    When I use the word over I don't refer to a fraction or division problem I refer to something occurring over a period of time.

    The problem with this calculation is that the railgun mentioned discharged its energy over a fraction of a second. Your calculation provides a power of around 9000W: in reality, it would be more like 3300000000W (almost 4.5million horsepower), based on a guesstimation of a 0.01s discharge time.

    Could you please explain more thoroughly. Time plays no role in these calculations. If something is 33 gigajoules, it is 33 gigajoules for a second, and 33 gigajoules for a day. It is just 33 gigajoules.

    Ha ha, I was just doing some math and you are just a failure. 33 gigajoules is 3,000,000,000 joules. That number is one 0 short of your number (typo probably). Also sure you may get 4.5 million hp (DON'T QUOTE ME I AM USING YOUR DATA AND IT IS TOO LATE AT NIGHT FOR ME TO CHECK IT), but you only get 4.5 million hp for 0.01 seconds. If you calculate that out which I can't think of how to do at this time you will only have a few horsepower over the course of a short time.

    -to everyone other than 06sandj Please disregard this post as the information is useless and just a poorly compile explanation of the massive fail seen above.

    Yes, the energy is the same, no matter the amount of time; however, you were quoting power, which does include time. The 4.5million hp came from google calculator (3300000000 watts in horsepower) - I'm not exactly a units conversion wizard myself :P I get your point, and it's true what you're saying about powering a city for a year - I was just attempting to point out that you were referring to the power of this particular railgun as 12hp. This may have just been unclear writing or me not understanding your comment particularly well. On the whole, we should probably forget all about this conversation, agree that railguns are pretty awesome, and continue with life :)

    oh, no, I wasn't saying the railgun had 12 hp, but the idea that it produces 4.5 million for 0.01 seconds is kinda cool

    All cleared up then :) And yes, it is :P Imagine the recoil on that thing - slight problem to firing it from a ship!

    ok im not very experienced with this subject, but to my understanding recoil is caused by the expanding gasses from the explosion of gunpowder (or whatever other explosive propelent you could use). so as long as you only used magnetic fields to eccelerate your projectile, and made shure to ventilate the rails, or barrel used to house your projectile, the only recoil you should experience should only be (not shure exactly how to say this, but hopefully this will work) the guns movement related to the inertia of the projectile which would keep it resting. if any of that is wrong plaese correct me.

    Every action has an equal but opposite reaction (one of them newton laws). When the magnetic field pushes the projectile the projectile pushes back just as hard. Now on a small railgun you won't notice it because the projectiles are usually very small and not going very fast, but the navy gun shoots a very heavy projectile at extreme unimaginable speed, this results in a huge amount of opposite force.

    yeah i know about newtons third law but (and again im not very experienced with this) wouldent the force of the "opppsite force" be distributed more or less evenly into the gun (kinda like if a baseball hits a barrel of water, the barrel doesent go flying at the same speed the baseball was traveling) so if a railgun which accelerates a 40 lb projectile to 5,500 mph, which i roughly calculated to require about 54.5 million joules (or 1.36 million joules per pound), was mounted in a platform weighing 5,000 pounds it would only have a recoil of around 272 joules (around twice the recoil of a barret .50) which i think a 16 million pound ship could easily take. now im shure i made some mistake somewere in there so please correct me

    I'm not to great with the numbers either, but I think you are probably right, it shouldn't do too much to move the ship, but it would still be 5000 pounds pushing back at 272 joules, which I am sure you would feel. Being anywhere near the thing could be really dangerous I imagine. I wounder what the electromagnetic field around it looks like.

    yeah the biggest problem i could imagine is the cannon going off and taking anything magnetic that isnt tied down (and possibly part of the ship) with it. lol i can see the headlines now "navy sends railgun superweapon into battle, oblitorates enemy ship...and sinks own ship in the process"

    seeing where they got the energy and how big the power source is would also be funny.