rail/coil guns [Archive]

SlartyB

03-10-2002, 04:29 AM

Originally posted by Funkatronic
I'm in the process of doin a sci-fi story..

would a rail gun or a coil gun the size of a rifle be feasable???(for weapons, not propulsion)

Since it's Science Fiction - of course you can !! ;)

But seriously, it would be a bit of a push at the moment from a technological point of view, but it could be done. The main issue is that chemical explosives are still the easiest and most economical way of accelerating a projectile to a high velocity - right now.

talldude

03-10-2002, 04:42 AM

Originally posted by Funkatronic
I'm in the process of doin a sci-fi story..

would a rail gun or a coil gun the size of a rifle be feasable???(for weapons, not propulsion)

I think it would have to be powered by cold fusion or something similar, but yes, it is feasible. The US military has already made a railgun, but then again, it wasn't exactly hand held...I believe it was mounted on a tank (IIRC).

!shira!

03-10-2002, 12:41 PM

the gun itself could be handheld but the power supply wouldn't

nova

03-10-2002, 03:55 PM

Originally posted by talldude

I think it would have to be powered by cold fusion or something similar, but yes, it is feasible. The US military has already made a railgun, but then again, it wasn't exactly hand held...I believe it was mounted on a tank (IIRC).

Try a battleship. :D

The only one ever made militarily useful(and this was only on the edge of useful) had to be mounted on a ship.

I found this out when myself and some friends of mine built a small rail gun our senior year in high school. We could only shoot a BB about a foot or two and we had to have 3 dozen 1 farad capacitors and a huge power supply to do that.

Thats the main thing that prevents hand held rail guns. If a power source is ever developed that is small, light, and can deliver both high voltage and high ampage then it is possible to have a hand held rail gun.

Strogian

03-10-2002, 09:25 PM

How about one of those mini-fuel cells? :)

Funkatronic

03-10-2002, 11:14 PM

from what I've seen, railguns are tough to build...but coil guns are a bit easier, though will never have quite as much potential...

russ_watters

03-11-2002, 01:26 AM

Fuel cells don't create nearly enough power. There is nothing short of a handheld nuclear reactor that could power a handheld railgun. And in any case, the laws of physics make it unlikely a person could even hold onto one. Just imagine the kick!

SlartyB

03-11-2002, 11:35 AM

Originally posted by russ_watters
Fuel cells don't create nearly enough power. There is nothing short of a handheld nuclear reactor that could power a handheld railgun. And in any case, the laws of physics make it unlikely a person could even hold onto one. Just imagine the kick!

Why whould the recoil be any greater than a conventional rifle ? I agree that the power supply is the limiting factor in the feasability of a portable rail gun - but only in so far that it is difficult to deliver that much energy in such a short period of time. You don't need a nuclear reactor - just a lot of storage.

Mayson

03-11-2002, 07:38 PM

Think I saw this over at [H]ard|OCP:
http://scitoys.com/scitoys/scitoys/magnets/gauss.html

you can make your own Gauss Rifle, enjoy :)

As for the "Kick", I think it would follow the laws of conservation of linear momentum. (Total Mass of projectile and gun)*(initial velocity) = (Mass of gun) * ( velocity of gun) + (mass of projectile) * (velociity of projectile).

If the projectile was fairly heavy and traveled extremely fast, and was fired from a light gun then you might have a problem. I think I read somewhere about the CIA (Maybe?) developing an extremely light gun made of plastics etc. so light in fact that it was lighter than the projectiles it fired. In that case, the gun had more "backwards" velocity than the projectile had "forewards" velocity.

Blacktooth

03-11-2002, 10:37 PM

I recently saw a show on either TLC or a Discovery channel title Future Guns. One was a rail gun. It took up a room and fired a steel (or exotic alloy) about a foot long and looked about an inch or two diameter at 1.5 MPS! It totally demolished a large concrete embankment without any explosive warheads. The reload time was rather quick as well. The "barrel" wasn't all that long either, so I imagine the acceleration from rest to 1.5 MPS in ~10 feet of an object weighing a few pounds at least, would make quite a recoil. Amazingly enough the reload time was rather quick, a few seconds.

We won't see any "hand-held" models until some major energy producing breakthroughs occur. It took MegaWatts to power the one in the show.

SlartyB

03-12-2002, 12:04 PM

Originally posted by Blacktooth
I recently saw a show on either TLC or a Discovery channel title Future Guns. One was a rail gun. It took up a room and fired a steel (or exotic alloy) about a foot long and looked about an inch or two diameter at 1.5 MPS! It totally demolished a large concrete embankment without any explosive warheads. The reload time was rather quick as well. The "barrel" wasn't all that long either, so I imagine the acceleration from rest to 1.5 MPS in ~10 feet of an object weighing a few pounds at least, would make quite a recoil. Amazingly enough the reload time was rather quick, a few seconds.

We won't see any "hand-held" models until some major energy producing breakthroughs occur. It took MegaWatts to power the one in the show.

The *energy* in the projectile is given by ....

M * V * V / 2

Assuming most of the energy consumed by the weapon was transferred to the projectile, and sing some approximate numbers from your post ....

E = 2kg * 2400m/s * 2400m/s / 2 = about 6 Million Joules.

Now, Power is defined as de/dt, I haven't got time to work out exactly how long it took to get from one end of the barrel to the other, but if it was about 2ms, the the *power* required is

6x10^6 / 0.002 = 3 GigaWatts

However ther power is only needed for a very short period of time. If it has a reload time of - say 6 seconds - the the *average* power required is ....

6x10^6 / 1 = 6 MegaWatts.

This is in agreement with the numbers in the program. Interesting ....

Blacktooth

03-13-2002, 12:29 AM

If you wanna see some awesome firepower check out this technology.
Metal Storm (http://www.metalstorm.com/10_technology/technology.html)

A million rounds a second!

russ_watters

03-13-2002, 01:45 AM

Why whould the recoil be any greater than a conventional rifle ?"

The entire point of a rail gun is to fire projectiles at enourmous velocity. And that creates the kick as Mayson showed with the math.

"I agree that the power supply is the limiting factor in the feasability of a portable rail gun - but only in so far that it is difficult to deliver that much energy in such a short period of time. You don't need a nuclear reactor - just a lot of storage."

It may be true that the energy for a shot can be held in a battery the size of a car battery (I don't feel like doing the math, but if anyone wants to, feel free), but another problem is getting the power out quickly. To do that requires storing it temporarily in capacitors, which also take up a lot of space.

SlartyB, your math looked good except for the size of the projectile - much too big for a handheld gun, and the projectile speed - much too slow. But cut the size by a factor of 10 and increase the speed by a factor of 10 (and square it) and you end up with 30 GW total power output. Of course increasing the speed decreases the time, which further increases the power output...

The point all remains the same though. Kind of energy required to propel a projectile is currently best produced by an explosion. Hypervelocity projectiles are cool, but use on a small scale will probably always be science fiction.

BTW though - NASA has looked into using railguns or simple air rifles (well, not quite so simple - they would use heated, compressed H2 gas) to lauch satellites. Mount one a mile long on the side of a mountain and you can accelerate a projectile to orbital velocity. Of course the projectile has to be pretty rugged to survive the acceleration....

mathius grey

03-13-2002, 08:34 AM

DERA in britain (like DARPA in the US) made one years ago, but it was the size of a house!

CadetLee

03-13-2002, 09:42 AM

Remember computers 50 years ago? A world market for maybe 5 computers...then 640k should be enough for anybody. I think railguns will eventually be practical - look at the technological advancements in the last 75 years, and imagine 75 years down the road. It will be interesting, at least..I know that much :)

SlartyB

03-13-2002, 11:47 AM

Originally posted by russ_watters

SlartyB, your math looked good except for the size of the projectile - much too big for a handheld gun, and the projectile speed - much too slow. But cut the size by a factor of 10 and increase the speed by a factor of 10 (and square it) and you end up with 30 GW total power output. Of course increasing the speed decreases the time, which further increases the power output...

The point all remains the same though. Kind of energy required to propel a projectile is currently best produced by an explosion. Hypervelocity projectiles are cool, but use on a small scale will probably always be science fiction.

I was simply verifying the numbers quoted by Blacktooth from the TV program he watched. Those number were not meant as a hard-and-fast definition for a hand-held weapon.

BTW though - NASA has looked into using railguns or simple air rifles (well, not quite so simple - they would use heated, compressed H2 gas) to lauch satellites. Mount one a mile long on the side of a mountain and you can accelerate a projectile to orbital velocity. Of course the projectile has to be pretty rugged to survive the acceleration....

It has already been done in Britain (ahead of the USA, for once). The same man who designed the Iraqi "Supergun" that was discovered during the end the Gulf War, designed a gun that could put a small projectile into orbit. AFAIK, no actual satellites were put into orbit, but I have seen film of it in action.

Don Flamenco

03-14-2002, 03:51 AM

shoot a 2 projectiles in opposite directions :P no more recoil! need more power though

Blacktooth

03-14-2002, 08:47 PM

Good idea Don. If only there was a way to make one of the projectiles make a U-turn after fired and follow the same trajectory as the other one...

I would think though, that if an ample power supply could be shrunk down to a portable size, the recoil issue would be a relatively easy one to tackle.

!shira!

03-14-2002, 09:38 PM

me and my friend are going to build a coil gun

do any of you know of a cap off radioshack.com is like that of a flash camera cap

dighn

03-14-2002, 10:24 PM

build caps yourselves with beer bottles!! it would be very cheap. i would imagine lots of high quality high voltage capacitors would be very expensive... it might take quite a few though AHHAHAHA

actually i'm sure there are better ways to build capacitors yourselves.. just search on google or something

just be careful with it. capacitors charged with HV == stuff you do not want to get too close to

SlartyB

03-15-2002, 01:17 AM

Originally posted by !shira!
me and my friend are going to build a coil gun

do any of you know of a cap off radioshack.com is like that of a flash camera cap

dighn has already warned you - but I feel something stronger is in order - just so it really sinks in.

UNLESS YOU *REALLY* KNOW WHAT YOU ARE DOING AND TAKE ADAQUATE SAFETY PRECAUTIONS, CONSTRUCTING YOUR OWN CAPACITORS AND CHARGING THEM TO A HIGH VOLTAGE *WILL* KILL YOU. HIGH VOLTAGE POWER SUPPLIES HAVE NO MERCY ON THE FOOLISH

dighn

03-15-2002, 02:18 AM

on second thought don't mess with that stuff. you do not want to be on the darwin award ;)

it's too dangerous to do as a hobby/side project. HV can jump across the air and break down ordinary "insulators" so it's not safe to handle.

so don't do it unless you are a professional :)

!shira!

03-15-2002, 08:52 AM

Originally posted by SlartyB

dighn has already warned you - but I feel something stronger is in order - just so it really sinks in.

UNLESS YOU *REALLY* KNOW WHAT YOU ARE DOING AND TAKE ADAQUATE SAFETY PRECAUTIONS, CONSTRUCTING YOUR OWN CAPACITORS AND CHARGING THEM TO A HIGH VOLTAGE *WILL* KILL YOU. HIGH VOLTAGE POWER SUPPLIES HAVE NO MERCY ON THE FOOLISH

this is why I am going to start with camera flash caps and a 12VDC powersupply
as for making my own caps, I doubt it in the near future, those are dangereous because you don't know the limits on them and homemade things tend to fail sometimes

Blacktooth

03-15-2002, 07:15 PM

TV sets have some big caps in them as well.

dighn

03-15-2002, 07:36 PM

Originally posted by !shira!

this is why I am going to start with camera flash caps and a 12VDC powersupply
as for making my own caps, I doubt it in the near future, those are dangereous because you don't know the limits on them and homemade things tend to fail sometimes

you don't need camera flash caps with a 12VDc source. just ordinary ones with voltage ratings well above 12 is fine (like 30 VDC). you may need to take into account the induced voltage from the coil though cuz you dont want that to break down the capactiros... a lot of diodes might work

talldude

03-15-2002, 10:49 PM

That would be cool to make a coil gun...but it's not gonna be very powerful. I'd just stick to the good old spud gun if i were you ;)

I've made 3 of those bad-boys, best one launched a potato over 200 meters :D

!shira!

03-16-2002, 07:39 PM

I'm using flash camera caps becasue I have several of them

stoo

03-16-2002, 09:42 PM

I remember that my physics teacher made a capacitor from tinfoil and clingfilm. And accidentally discharged it through himself* :rolleyes:

(*He didn't actually hurt himself)

nova

03-17-2002, 12:00 AM

Microwaves have high capacity capacitors too. They are real high volatage though. You'd probably have to use the power supply from the microwave which is like 100X more juice than needed to kill you. Needless to say it wouldn't be very safe.

!shira!

03-17-2002, 10:46 AM

if I had a microwave I could take apart I would get the magnetron out and cook thing from several feet away :)

nova

03-17-2002, 09:08 PM

Originally posted by !shira!
if I had a microwave I could take apart I would get the magnetron out and cook thing from several feet away :)

You'd probably cook yourself too. :D :p

If I'm not mistaken if you ever needed to build a radio transmitter most of the major components to do build one are in a microwave. All it would require was some minor modifications.

jester22c

03-18-2002, 05:35 PM

Originally posted by CadetLee
Remember computers 50 years ago? A world market for maybe 5 computers...then 640k should be enough for anybody. I think railguns will eventually be practical - look at the technological advancements in the last 75 years, and imagine 75 years down the road. It will be interesting, at least..I know that much :)

This is true, but then again a computer has proved useful to most people today. A railgun is a bit extreme. I mean we already have high powered rifles etc. Civilians won't have much need for such a high powered firearm. I mean whatever you're shooting at can be mangled/killed/whatever with a severely less powerful weapon. If you're a hunter and you shoot a deer with a railgun it is going to either explode or have a hole in it the size of a watermellon. Either way it wouldn't be too practical lol. Even if you want it for self defense.. it would be nice to know who you just obliviated. I do think the technology will get there, but I don't think the usability for the average American will.

nova

03-18-2002, 07:49 PM

Originally posted by jester22c

This is true, but then again a computer has proved useful to most people today. A railgun is a bit extreme. I mean we already have high powered rifles etc. Civilians won't have much need for such a high powered firearm. I mean whatever you're shooting at can be mangled/killed/whatever with a severely less powerful weapon. If you're a hunter and you shoot a deer with a railgun it is going to either explode or have a hole in it the size of a watermellon. Either way it wouldn't be too practical lol. Even if you want it for self defense.. it would be nice to know who you just obliviated. I do think the technology will get there, but I don't think the usability for the average American will.

Militarily there is the problem of how far the projectile will travel. Fratricide is a real problem with tanks shells that travel 2-3 miles. It would be much great with a projectile that could theoretically travel 10X as far.

!shira!

03-18-2002, 10:00 PM

Originally posted by nova

Militarily there is the problem of how far the projectile will travel. Fratricide is a real problem with tanks shells that travel 2-3 miles. It would be much great with a projectile that could theoretically travel 10X as far.
true but there would be no flame from the barrel of the tank
that way, your position wouldn't be given away to the enemy visually

as for fratricide, by the time we are mounting rail/coil guns on tanks they will have better iff (anyways we have shot at own own abrams tanks and the armor is so good that is survived :D )

nova

03-19-2002, 08:27 PM

THis I know. I'm in ROTC and several of our CADRE fought in the Gulf War.

You do have to worry about the Bradleys and such though. They aren't quite as tough.

Plus what do you do if you miss and accidentally wipe out a town or something. Civy casualties are frowned upon.

Sparky_D

03-20-2002, 11:30 AM

Originally posted by nova

Plus what do you do if you miss and accidentally wipe out a town or something. Civy casualties are frowned upon.

Frowned upon?! :rolleyes:

Pestilence

03-20-2002, 03:20 PM

Originally posted by nova
Plus what do you do if you miss and accidentally wipe out a town or something. Civy casualties are frowned upon.

That would be an understatement if I ever saw one.

alanpennington

03-22-2002, 06:06 PM

Originally posted by Sparky_D

Frowned upon?! :rolleyes:

It depends on what side you are on. Some countries aren't that particular about civilian casualities except as propaganda. As for a market for a railgun, I think Saddam Hussien or Osama bin Ladin would buy it. Your ground troups would be quite formidable.

!shira!

03-24-2002, 01:05 PM

Originally posted by alanpennington

It depends on what side you are on. Some countries aren't that particular about civilian casualities except as propaganda. As for a market for a railgun, I think Saddam Hussien or Osama bin Ladin would buy it. Your ground troups would be quite formidable.
true but osama would need to power it with something and there usually aren't power outlets in caves