Building a Railgun. [Archive] - Wizards Community

Building a Railgun. [Archive] - Wizards Community

Post/Author/DateTime Post
Frodo34x
12-21-06, 10:41 AM I was wondering, what would be the best way to build a railgun in DnD?
The basic way a railgun works is by having two rails, and then creating a force (usually electromagnetic) that goes along the rails, and pushes the object as it goes. For these examples, the ammunition will be a simple Uranium Sword. Feel free to replace it with a rock/ goblin/ Tarrasque/ other object (deplete as applicable).
Here are a couple of ideas I thought up.

Have a permanent Reverse Gravity aimed horizontally, so that it basically fires the object at 10ms-2

===============Rail
00000000000000000
) -+==>
00000000000000000
================Rail

) = reverse Gravity point, pushing the object forwards
0 = More reverse gravities, this time to keep it from hitting the rails.
Not sure how well this would work. For a start, it requires that reverse gravity can be used horizontally, which I don't think it can.

Here's a refinement on the one above:
Replace the Reverse Gravity point thing with a permanent Repel Metal, such that it repels all metal objects place into the firing chamber. Maybe even someway to switch it on and off? You probably also only need Reverse Gravity applied on the bottom rail, and a very small anti magic field on the top one, so that when the object falls up, it hits the anti-magic field, and falls again, before being thrust up again, etc. Disadvanteges to this, is that the object only moves 40 feet in a round. On a reverse-grav railgun with a metre long barrel, and assuming negligible air resistance, according to my (probably unreliable) calculations, it would move 120feet, reaching a top speed of 23ft/s, or 17mph.
Question - Does anyone know if it is possible to stack multiple Repel Metals to create a faster speed? If so, you could somehow activate 90000000 to acheive a speed close to the speed of light.
The old fashioned way - Through several DC 50 knowledge(electromagnetism) checks, the character knows how to electromagnets to build a 'real' railgun. I don't know exactly how to get electricity - probably build some form of capacitor to store lightning in. Obviously, this method would be the hardest to do, as it requires huge powerpacks of stored lightning to work, and an INT score in about the triple figures (not to mention max skill ranks in knowledge(electromagnetism) and proffesion(electo-physicist)).

So, does anyone know whether any of these would actually work? What about any other methods for a railgun type projectile weapon?
Now obvioulsy, unless we can stack our repulsion spells, we will never really get a true railgun; that is, one that causes the air in close proximity to the projectile to ignite through etremely high friction [After all, FFriction o< F object], leaving a trail of pretty lights.
Tyler Do'Urden
12-21-06, 01:06 PM You have a line of commoners each ready an action to pass a bucket from the person on his left to the person on his right. The actions occur at the same initiative of the same round, so the acceleration generated by this is limited only by the length of the line.
Aexalon
12-21-06, 01:47 PM You might want to examine the wikipedia page on Railguns (http://en.wikipedia.org/wiki/Railgun). "True" railguns work by hitting the rails with a massive electrical jolt (which travels down one rail, through the projectile, and back up the other rail again), where through the interaction between the current running through the projectile and the magnetic field surrounding the rails generated by the pulse passing through them, the only mobile part of the setup, the projectile, is accelerated off the rails.

Major problems in railgun construction are
1) getting a power source capable of generating a massive current pulse;
2) constructing a set of rails that won't be blasted apart by the interaction between their respective magnetic fields;
3) preventing the projectile from welding itself to the rails due to the heat generated by the electrical pulse having to cross the high-resistance connection between the rails and the projectile.

If someone wanted to build a magitech railgun, I'd rule it needed to be powered by an electrical spell (one casting/charge per shot), would be a ranged touch attack with a range increment of some 200' (400' if you're mounting a spyglass or something onto it to actually see that far; maximum of 10 range increments as is normal for a projectile weapon), do base projectile damage + 1/2 the damage dice of the spell powering the gun, deal piercing damage (modified by properties or enchantments of the projectile), and probably require that the rails be replaced every 5 to 10 shots. Add some bad stuff happening if you roll a 1 on the attack roll (ranging from the projectile welding to the rails, requiring immediate rail replacement, to the entire assembly blowing up, destroying the railgun and damaging the gunner and others adjacent to the gun), and you're good to go.

And if it wasn't clear: this is an emplacement weapon, much like a ballista; not the hand-held device popularised in the Quake FPS games. Reloading, aiming and firing: 1 full-round action (which includes a standard action to cast the spell, or trigger an item, into the gun); replacing the rails: 1 minute (at best).
Quixotico
12-21-06, 02:01 PM Not sure I can help with the gun itself, but try loading it with a Brilliant Energy throwing knife to replicate the penetrating effects. Add on Returning for more fun per round.
tarkin
12-21-06, 02:10 PM You appear to be doing what I call the "Mad Scientist that thinks he is a Wizard" fantasy progam.

How to do this program:

1) take a spell that has limitations (such as Reverse Gravity only working vertical).

2) change the spell, removing the limitations that were intionally put in to stop the kinds of things you want to do.

3) make it permanent in some way, then claim that you have created a new item x.

You want a rail gun?

Make a spell called RAIL GUN

You want it permanent? When you write up the spell, say it can be made permanent or turn it into a magic item.

Advantage of doing it my way:

You can put in reasonable limitations, follow standard spell creation rules, and do other things that make it fair, preventing abuses and letting everybody do it without making the game boring.

Advantage of doing it your way:

You don't have to do anything I said above, and can instead make it way over-powered.
Rulebook
12-21-06, 03:45 PM passing an object from person to person is a free action. i havent heard anything about this not being possible multiple times. quarterstaves are free. so ill go from there.

you and 2 other buddies form a circle.
you craft a quarterstaff as a free action (0 cost)
you pass the quarterstaff around as free actions many many many times

soon you approach the speed of light, and you release your quarterstaff as a bolt of near pure energy. damage is caluclated using einstiens mass-energy conversion equation.
enygmatic_me
12-21-06, 03:57 PM The one thing I need to know about is who is carrying around Uranium swords to use as ammo?

You create a massively powerful weapon only to die of cancer in a year or two? I guess you could walk around in a lead suit of platemail, but then you risk lead poisoning.

You could just make an firearm type weapon based around the Ring of the Ram that uses projectiles. Less chance of cancer and no real chance of lead poisoning that way.
xhado123
12-21-06, 05:24 PM Um... HI. I'm new to these forums, but not to online posting.

I have one question to ask: should I be scared that you know how to build these?
Quixotico
12-21-06, 05:31 PM Scared that somone knows how to build a railgun? Pfft. Child's play, really. The Internet is crawling with information on how to build much worse. If you know where to look and have the mind to study it, the information is yours for the taking.
ruff0126
12-21-06, 05:35 PM No, anyone on these boards tend to pick up little things like this. No worries:plotting:
Angatyr
12-21-06, 06:22 PM Spell: Railgun
Sor/Wiz 4

ranged touch to throw medium one handed weapon sized or smaller projectile in line 50ft/clvl long.
deals damage equal to projectile damage/clvl (max 15)
each target takes 1 projectile damage less. Maximum targets clvl/2
ignores hardness.

eg:
lvl 10 wiz casts on +1 longsword,
longsword flies in a 500ft line, dealing 10d8+10 to first creature/object, 9d8+9 to second, 8d8+8, 7d8+7, 6d8+6, no more targets.

what do you think??
Alcalientre
12-21-06, 07:51 PM It might be a little overpowered, but only if you use expensive ammo. If you're using ammo that you don't care about losing, such as a dagger, it seems underpowered. I thing it's allright.
CryoSilver
12-21-06, 07:59 PM Um... HI. I'm new to these forums, but not to online posting.

I have one question to ask: should I be scared that you know how to build these?

Bah. I built a gauss rifle for a high school English project. It's not so hard.
Lord_Tirian
12-21-06, 08:05 PM Scared that somone knows how to build a railgun? Pfft. Child's play, really. The Internet is crawling with information on how to build much worse. If you know where to look and have the mind to study it, the information is yours for the taking.
E-X-A-C-T-L-Y.

Additionally, the knowledge is worth nothing. Having the means and resources - as well as a bunch of fine-tuning engineers to increase efficiency - is the *really* valuable resource.

See: A nuclear weapon is simple as hell: Take two highly active pieces of radioactive material (like Uranium - but the right sort of it), calculate the critical mass (not that hard), then push them together to initiate the chain reaction.

Now to the building: This becomes a heck more difficult, because you want the most efficient explosion... and oh yeah, you want to get refined Uranium/other useable radioactive material. And that engineering is darn expensive and difficult as hell.
Jaid
12-21-06, 08:09 PM if you don't care about size of the launcher, the lightning rail from eberron is handy for building railgun-like weapons.
Radijs
12-22-06, 09:39 AM Now there's an idea a for a plot. A malevolent group using the lightning rail to attack cities by lurching dangerous things in the city.
Quixotico
12-22-06, 12:32 PM To keep in spirit of a Railgun, Angatyr, I'd suggest limiting the ammor to be used on your Spell Railgun to be ammo only, (including shuriken and throwing knives if they aren't applicable otherwise) and equivilant to your size or smaller. So a Medium creature couldn't launch a Large Arrow. If this underpowers the spell too much, and it very may well, then add in that it ignores DR.
Radijs
12-22-06, 03:06 PM If I where to build a railgun I'd put it to work as a siege engine. Hurling iron balls at the gates of my enemies.
hiryuu
12-22-06, 07:10 PM if you don't care about size of the launcher, the lightning rail from eberron is handy for building railgun-like weapons.

Not really.

All the rail does is create a "tunnel" of air in which the carriage rests. The propulsion is provided by the elemental in the lead carriage, and the absolute best it can do is the breakneck speed of.... 30 miles an hour.

In order to use it as a weapon, you'd have to enhance the ammuntion by binding an elemental to it, which is far too expensive for a 30-mile-an-hour spike.

It's Eberron. If it could be used as a weapon, it'd exist already.
Angatyr
12-22-06, 09:45 PM I think I will make it a lvl 5 spell with no save to avoid damage. also any armour worn by the first target takes 1/2 the damage the target takes;
the projectile falls to the ground at max range, or sticks in if it fails to destroy a stationary object (wall), itself taking half damage.
I already limited the size to equal to or smaller than a medium one handed weapon, so d8 is the most damage you can get. I think a higher lvl spell can use larger objects and has a higher damage limit, and a 9th lvl can throw creatures as the projectile into other targets.
imagine shooting a dragon with an orc! :D
Name: Sarik's Sundering Shot, improved and greater for the variants mentioned.

Post/Author/DateTime	Post
Frodo34x 12-21-06, 10:41 AM	I was wondering, what would be the best way to build a railgun in DnD? The basic way a railgun works is by having two rails, and then creating a force (usually electromagnetic) that goes along the rails, and pushes the object as it goes. For these examples, the ammunition will be a simple Uranium Sword. Feel free to replace it with a rock/ goblin/ Tarrasque/ other object (deplete as applicable). Here are a couple of ideas I thought up. Have a permanent Reverse Gravity aimed horizontally, so that it basically fires the object at 10ms-2 ===============Rail 00000000000000000 ) -+==> 00000000000000000 ================Rail ) = reverse Gravity point, pushing the object forwards 0 = More reverse gravities, this time to keep it from hitting the rails. Not sure how well this would work. For a start, it requires that reverse gravity can be used horizontally, which I don't think it can. Here's a refinement on the one above: Replace the Reverse Gravity point thing with a permanent Repel Metal, such that it repels all metal objects place into the firing chamber. Maybe even someway to switch it on and off? You probably also only need Reverse Gravity applied on the bottom rail, and a very small anti magic field on the top one, so that when the object falls up, it hits the anti-magic field, and falls again, before being thrust up again, etc. Disadvanteges to this, is that the object only moves 40 feet in a round. On a reverse-grav railgun with a metre long barrel, and assuming negligible air resistance, according to my (probably unreliable) calculations, it would move 120feet, reaching a top speed of 23ft/s, or 17mph. Question - Does anyone know if it is possible to stack multiple Repel Metals to create a faster speed? If so, you could somehow activate 90000000 to acheive a speed close to the speed of light. The old fashioned way - Through several DC 50 knowledge(electromagnetism) checks, the character knows how to electromagnets to build a 'real' railgun. I don't know exactly how to get electricity - probably build some form of capacitor to store lightning in. Obviously, this method would be the hardest to do, as it requires huge powerpacks of stored lightning to work, and an INT score in about the triple figures (not to mention max skill ranks in knowledge(electromagnetism) and proffesion(electo-physicist)). So, does anyone know whether any of these would actually work? What about any other methods for a railgun type projectile weapon? Now obvioulsy, unless we can stack our repulsion spells, we will never really get a true railgun; that is, one that causes the air in close proximity to the projectile to ignite through etremely high friction [After all, FFriction o< F object], leaving a trail of pretty lights.
Tyler Do'Urden 12-21-06, 01:06 PM	You have a line of commoners each ready an action to pass a bucket from the person on his left to the person on his right. The actions occur at the same initiative of the same round, so the acceleration generated by this is limited only by the length of the line.
Aexalon 12-21-06, 01:47 PM	You might want to examine the wikipedia page on Railguns (http://en.wikipedia.org/wiki/Railgun). "True" railguns work by hitting the rails with a massive electrical jolt (which travels down one rail, through the projectile, and back up the other rail again), where through the interaction between the current running through the projectile and the magnetic field surrounding the rails generated by the pulse passing through them, the only mobile part of the setup, the projectile, is accelerated off the rails. Major problems in railgun construction are 1) getting a power source capable of generating a massive current pulse; 2) constructing a set of rails that won't be blasted apart by the interaction between their respective magnetic fields; 3) preventing the projectile from welding itself to the rails due to the heat generated by the electrical pulse having to cross the high-resistance connection between the rails and the projectile. If someone wanted to build a magitech railgun, I'd rule it needed to be powered by an electrical spell (one casting/charge per shot), would be a ranged touch attack with a range increment of some 200' (400' if you're mounting a spyglass or something onto it to actually see that far; maximum of 10 range increments as is normal for a projectile weapon), do base projectile damage + 1/2 the damage dice of the spell powering the gun, deal piercing damage (modified by properties or enchantments of the projectile), and probably require that the rails be replaced every 5 to 10 shots. Add some bad stuff happening if you roll a 1 on the attack roll (ranging from the projectile welding to the rails, requiring immediate rail replacement, to the entire assembly blowing up, destroying the railgun and damaging the gunner and others adjacent to the gun), and you're good to go. And if it wasn't clear: this is an emplacement weapon, much like a ballista; not the hand-held device popularised in the Quake FPS games. Reloading, aiming and firing: 1 full-round action (which includes a standard action to cast the spell, or trigger an item, into the gun); replacing the rails: 1 minute (at best).
Quixotico 12-21-06, 02:01 PM	Not sure I can help with the gun itself, but try loading it with a Brilliant Energy throwing knife to replicate the penetrating effects. Add on Returning for more fun per round.
tarkin 12-21-06, 02:10 PM	You appear to be doing what I call the "Mad Scientist that thinks he is a Wizard" fantasy progam. How to do this program: 1) take a spell that has limitations (such as Reverse Gravity only working vertical). 2) change the spell, removing the limitations that were intionally put in to stop the kinds of things you want to do. 3) make it permanent in some way, then claim that you have created a new item x. You want a rail gun? Make a spell called RAIL GUN You want it permanent? When you write up the spell, say it can be made permanent or turn it into a magic item. Advantage of doing it my way: You can put in reasonable limitations, follow standard spell creation rules, and do other things that make it fair, preventing abuses and letting everybody do it without making the game boring. Advantage of doing it your way: You don't have to do anything I said above, and can instead make it way over-powered.
Rulebook 12-21-06, 03:45 PM	passing an object from person to person is a free action. i havent heard anything about this not being possible multiple times. quarterstaves are free. so ill go from there. you and 2 other buddies form a circle. you craft a quarterstaff as a free action (0 cost) you pass the quarterstaff around as free actions many many many times soon you approach the speed of light, and you release your quarterstaff as a bolt of near pure energy. damage is caluclated using einstiens mass-energy conversion equation.
enygmatic_me 12-21-06, 03:57 PM	The one thing I need to know about is who is carrying around Uranium swords to use as ammo? You create a massively powerful weapon only to die of cancer in a year or two? I guess you could walk around in a lead suit of platemail, but then you risk lead poisoning. You could just make an firearm type weapon based around the Ring of the Ram that uses projectiles. Less chance of cancer and no real chance of lead poisoning that way.
xhado123 12-21-06, 05:24 PM	Um... HI. I'm new to these forums, but not to online posting. I have one question to ask: should I be scared that you know how to build these?
Quixotico 12-21-06, 05:31 PM	Scared that somone knows how to build a railgun? Pfft. Child's play, really. The Internet is crawling with information on how to build much worse. If you know where to look and have the mind to study it, the information is yours for the taking.
ruff0126 12-21-06, 05:35 PM	No, anyone on these boards tend to pick up little things like this. No worries:plotting:
Angatyr 12-21-06, 06:22 PM	Spell: Railgun Sor/Wiz 4 ranged touch to throw medium one handed weapon sized or smaller projectile in line 50ft/clvl long. deals damage equal to projectile damage/clvl (max 15) each target takes 1 projectile damage less. Maximum targets clvl/2 ignores hardness. eg: lvl 10 wiz casts on +1 longsword, longsword flies in a 500ft line, dealing 10d8+10 to first creature/object, 9d8+9 to second, 8d8+8, 7d8+7, 6d8+6, no more targets. what do you think??
Alcalientre 12-21-06, 07:51 PM	It might be a little overpowered, but only if you use expensive ammo. If you're using ammo that you don't care about losing, such as a dagger, it seems underpowered. I thing it's allright.
CryoSilver 12-21-06, 07:59 PM	Um... HI. I'm new to these forums, but not to online posting. I have one question to ask: should I be scared that you know how to build these? Bah. I built a gauss rifle for a high school English project. It's not so hard.
Lord_Tirian 12-21-06, 08:05 PM	Scared that somone knows how to build a railgun? Pfft. Child's play, really. The Internet is crawling with information on how to build much worse. If you know where to look and have the mind to study it, the information is yours for the taking. E-X-A-C-T-L-Y. Additionally, the knowledge is worth nothing. Having the means and resources - as well as a bunch of fine-tuning engineers to increase efficiency - is the really valuable resource. See: A nuclear weapon is simple as hell: Take two highly active pieces of radioactive material (like Uranium - but the right sort of it), calculate the critical mass (not that hard), then push them together to initiate the chain reaction. Now to the building: This becomes a heck more difficult, because you want the most efficient explosion... and oh yeah, you want to get refined Uranium/other useable radioactive material. And that engineering is darn expensive and difficult as hell.
Jaid 12-21-06, 08:09 PM	if you don't care about size of the launcher, the lightning rail from eberron is handy for building railgun-like weapons.
Radijs 12-22-06, 09:39 AM	Now there's an idea a for a plot. A malevolent group using the lightning rail to attack cities by lurching dangerous things in the city.
Quixotico 12-22-06, 12:32 PM	To keep in spirit of a Railgun, Angatyr, I'd suggest limiting the ammor to be used on your Spell Railgun to be ammo only, (including shuriken and throwing knives if they aren't applicable otherwise) and equivilant to your size or smaller. So a Medium creature couldn't launch a Large Arrow. If this underpowers the spell too much, and it very may well, then add in that it ignores DR.
Radijs 12-22-06, 03:06 PM	If I where to build a railgun I'd put it to work as a siege engine. Hurling iron balls at the gates of my enemies.
hiryuu 12-22-06, 07:10 PM	if you don't care about size of the launcher, the lightning rail from eberron is handy for building railgun-like weapons. Not really. All the rail does is create a "tunnel" of air in which the carriage rests. The propulsion is provided by the elemental in the lead carriage, and the absolute best it can do is the breakneck speed of.... 30 miles an hour. In order to use it as a weapon, you'd have to enhance the ammuntion by binding an elemental to it, which is far too expensive for a 30-mile-an-hour spike. It's Eberron. If it could be used as a weapon, it'd exist already.
Angatyr 12-22-06, 09:45 PM	I think I will make it a lvl 5 spell with no save to avoid damage. also any armour worn by the first target takes 1/2 the damage the target takes; the projectile falls to the ground at max range, or sticks in if it fails to destroy a stationary object (wall), itself taking half damage. I already limited the size to equal to or smaller than a medium one handed weapon, so d8 is the most damage you can get. I think a higher lvl spell can use larger objects and has a higher damage limit, and a 9th lvl can throw creatures as the projectile into other targets. imagine shooting a dragon with an orc! :D Name: Sarik's Sundering Shot, improved and greater for the variants mentioned.