Ok, I need some feedback for a weapon X and I are developing for our storyline. Basically, it's a handgun that uses railgun technology to fire it's bullets. We've already assumed the bullets will go faster than normal bullets, but how fast we're not sure. Also, we're trying to figure out what kind of sound would be made and any possible recoil.
So basically
1: How powerful/fast would the bullets be.
2: How loud/what type of sound would be made
3: How much recoil (if any) there would be.

Feedback is much appreciated.

Recoil = M*A (Mass times Acceleration)
Force = M*A^2

It would make a crack as the round broke the sound barrier. There would probably be an electronic whine as the capacitor charged.

I researched this for a story also. The weapons were known as Cannister Rifles as they had a canister of BB-sized silicon and aluminum rounds for ammo. They were only used by the MI (medium infantry) as their armour allowed enough ballast for them to use it. The mobile cavalry used similar technology in their mech weapons though.

3. Before you do anything else, state that there is a jar attached with faeries in it that compensate for the insane recoil or someone will make a stink about it. You don't have to make it realistic, because in reality a handgun that uses railgun tech to fire bullets at super-sonic speed, while it can be made, would take your arm off when you fire it, depending on the mass of your bullets. Then again, you don't want to use bullets that are too light or they'll burn up fast with friction and not reach great distance or they can be tossed about by even the slightest of turbulence. However, all of this can be solved with faeries. Or, I guess, naming it fiction and saying "If I wanted it to be real, I'd have written non-fiction."

2. Standard sonic boom sound. The loudness depends on how fast you want the bullets to go.

1. This is entirely arbitrary. That means, you get to pick a number out of your... head and apply it. Generally, the speed of sound is [332 + (0.6*temperatur in Celsius)]m/s (or about 747 mph at 0 degrees celsius). You want it to go Mach2, it will go Mach 2, and your other questions will derive from this one.

Actually, railguns apply their force outwards against the rails and not back. That's one of the problems with railguns, rail damage. Most need to be repaired after one shot. If you can get past the rail damage issue, all you have to do is weld some titanium rings around the barrel and you'll be able to get some awesome damage out of the railgun without getting laid on your ass by recoil.

If there was no force opposite the direction of bullet movement, there would be no movement. Since there is a force pushing the bullet parallel to the rails, you can easily see that there is an equal force pushing in the opposite direction. Which is backward. Which is into the mass of the wielder.

We've got a substance called Deuterium that'll be able to handle the force. But still wondering about sonic boom thing. I want to make the bullets go about mach 10. dunno if they'd burn up at that speed and if the sonic boom would be insane.

Aw, I was really hoping you'd use the faeries. They amuse me. ^_^

Well, first of all, if it's a handgun, you don't need mach 10. That's just taking it too far. With handguns, you fight opponents face-to-face. Usually, that means your within a few hundred meters or so. Outside that range, most people can't aim without correctional tools. However, it's fantasy, so you could side-step that issue if you really want. Then again, I'd really recommend Mach 2. It's going nearly 700 meters every second which makes it basically instantaneous to anything that can't react below, say 0.5 seconds at 350 meters. However, if you use super-humans or androids/robots, they may be able to break those barriers, but not by enough to warrant 3500 m/s travelling speed for bullets. Unless you are putting holes in tanks, of course. Still, using a handgun for that is complicated. If a handgun can be that damaging, what's the point of having tanks or other heavily-armoured mobile platforms of destruction?

Daemon: The spinning field is what the force is applied to. We've had this discussion before.

V=projectile
<Force-V-Force>
<Force-V-Force>
<Force-V-Force>
<Force-V-Force>
<Force-V-Force>

Deuterium is an isotope of hydrogen containing one neutron. It's what makes heavy water heavy.

You'd need to reach speeds along the lines of mach 30-40 before you have to worry about heat shielding the rounds.

So, what is the field applying it's force to that prevents the field from moving? I mean, the field can apply a force to the bullet, so it must be able to have a force applied to it by the bullet. Well, if it applies a force to the bullet, why is it forbidden from applying a force to the gun in the opposite direction of the bullet?

You want to prove me wrong? Fire a railgun and tell me it produces no recoil. I will laugh my ass off at whomever tries it when I get to watch their arm get torn off by the recoil. What you are saying is that the backward-reactionary force of the bullet magicially disappears. That violates the Law of Thermodynamics.

You ever performed the magnetic field experiment involving holding quickly spinning tire while standing on a freely-rotatable platform? If you are holding the tire upright, so an edge-on view would be similar to "|", nothing happens. Revolve the tire so it looks like "--" and suddenly you start to turn on the platform. Well, the circular acceleration of the tire creates a magnetic field that interacts with the magnetic field of the earth. Clearly, the forces with which the fields interact are carried over to the object you are holding. Same thing. Foce of the bullet carries to the field. Force of the field carries to the gun.

As I said before, shut up, shut up, it's fairies.

Daemon, go find us a science textbook that supports your view, specifically by TALKING about railguns, since SC's argument makes a lot more sense.

It doesn't, though. He has force that is just up and disappearing. Where does it go?

You want reason? Take two magnets. Put them near each other. Now, neither magnet acts on eachother. Each creates a field. You place them near each other, the magnets will move, either away from each other or toward each other, depending on orientation. Am I the only person that has ever observed this?

Same deal with the bullet and gun. You guys are insisting that one magnet will push the other magnet WITHOUT the second magnet pushing back.

TEXTBOOK.

How about Wikipedia which is the closest thing I have to an encyclopedia?

Rail_gun

Notice this quote:Too vague? Notice this personal enhancement:Now, the rails are part of the gun. Any force the rails feel, the gun feels, too. If the rails feel recoil OPPOSITE THE DIRECTION OF THE BULLET'S PROPULSION, then the whole of the gun does, too.

That's a gyroscopic effect, not magnetism.

The force doesn't go back, it pushes out to the sides. A railgun is built like a ladder. The bullet doesn't push against the steps, it pushes against the sides.

Wikipedia also includes a nice diagrahm.

Read it. It says there is a recoil force pushing against the gun in the direction of the bullet which is aligned with the rails.

This means, if the rails look like this:



And the bullet's propulsion follows like this:



It is saying there is recoil along the rails like this:


I don't even WANT to know how you get that it means something gyroscopic.

That diagram doesn't even reference the quote I'm talking about. The quote is made afterward. Please tell me, where in that quote, does it talk about ANY of the force in that picture? Using that diagram is using it out of context.

I lied. I do want to know what you mean by "gyroscopic" in relation to the force that "The force exerted on the rails consists of a recoil force - equal and opposite to the force propelling the projectile..." describes.

Corroberating railgun analyses:

About the movie, Eraser. Find the word "recoil" and read on.

Journal of Physics: Applied Physics. Railgun recoil and relativity. "In relativistic electromagnetism the recoil force of a railgun should act on the magnetic field and absorb field energy-momentum.The Ampere-Neumann electrodynamics, on the other hand, requires the recoil forces to reside in the railheads and push the rails back toward the gun breach. Experiment confirms the latter mechanism." Notice the LAST sentence. "Experiment confirms the latter mechanism" referring to "The Ampere-Neumann electrodynamics, on the other hand, requires the recoil forces to reside in the railheads and push the rails back toward the gun breach."

Wikipedia, again. This time, lower down, we find an explanation for why we don't have hand-gun-sized rail-guns: "The simple reason is that the destructive power of a handgun or long gun is limited as much by recoil as anything else; we can quite happily build a handgun that fires 20 mm cannon shells, but you couldn't fire it without having your hand broken." How does it break your hand, again?

I meant the thing about the tire and the rotating platform. That's gyroscopic action, a result of centrifugal force.

And as a follow-up, The Right Hand Rule.


Back on topic more, mach four would be better for the handgun. It would provide and improvement over standard chemical weapons.

The right hand rule dictates force applied to an object but makes no reference to any reactionary forces that the object makes in order to not violate Thermodynamics. You are using a lack of reference to justify a reference to a lacking. That means you are taking something out of context, again.

Seriously, take a look at that last link from wikipedia, and tell me what that says. If I were wrong, how could that quote be right? You have gone past the point of contrarian and appear to be refusing to consider my statements based solely on the fact that you don't want to be wrong.

In Daemon's defense, I pounded on him until he provided the Wiki quotes. Wiki, while not exactly authoritative (I'd prefer a physics textbook explanation of right-hand-rule as applied to railguns), does state that railguns wouldn't work for people because of (not stated but inescapably inferred) recoil issues. As I said, I don't find this a total clincher, but the only thing that could contest it, for me, would be quotes from paper books, preferably physics textbooks- or professors, or 3/4th year physics undergrads.

Okay, here's an example to explain the physics of where the recoil is going. The magnetic field around each rail is rotating opposite each other. Let's imagine that, instead of intangible fields, that there are two, smooth cylinders placed together, rotating in opposite directions. Now we place a bearing inbetween them so it touches both rails. The force of the rotation causes the bearing to slide down the rails and onto the floor. The direction will differ depending on which way the cylinders are spinning.

In a railgun the action, the imparting of energy to the projectile, takes place from the rails in towards the projectile. Thus the equal and opposite reactions will be to push the rail and the projectile apart. The second rail imparts equal energy from the opposite direction, forcing the projectile's reaction to take place perpindicular to the reaction of the rails, causing the projectile to move parallel to the rails. Most of the force is going to be imparted trying to throw the rails apart from each other. This leads to less recoil proportionally to chemical propellant based guns as in that reaction, the force is pushed directly backwards.

Does that make more sense?

No. It does not. Here's why.

It's very simple. Try to understand it without complexity because it's apparently easy to miss.

You almost missed it. Okay, now I'm just egging you on. I know it's wrong, but I'm an ass. What can I say? No one listens to me, anyways.

A Forward push of 100N will have a NET Backward(opposite) push of 100N in EXACTLY the OPPOSITE direction. That means, all of the angular and rotational forces applied in reverse will add up to 100N pointing the opposite direction that the bullet is being pushed.

Don't believe me? Draw up the vector diagrams to measure every single force involved. That one you linked earlier only deals with propulsionary forces on the bullet, but not the reactionary forces involved in that push.

No matter what the case, if you push on something, regardless of what you use to push on it - BARRING FAERIES - it will push back on you with equal force.

But the pushing is coming from the rails, not from behind the projectile. That means the reaction is going to be directed back at the source. The 100N will be forced back onto the rails, which are doing the pushing, not along the rails. In a coilgun, this would be the case. That's why everyone's so much more interested in railguns over coilguns.

No, the pushing is not coming from the rails. It's coming from a field that the rails, which are part of the gun, creates. The field pushes on the bullet. The bullet pushes backward on the field, and the field forces the whole gun backward as a result.