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Why does Gauss Rifle = no recoil?

What is the justification for the Gauss rifle having no recoil?
Newton's (1st, 2nd, or 3rd - pick one) Law Of Motion states that any action has an equal and opposite reaction.

The recoil in a 'firearm' is from the explosion of gunpowder - also the cause of any sound except for the whizz of the bullet through the air. You're not just pushing the bullet down the barrel of a normal rifle, but the gas and particulates of the explosion as well. And that has more mass then the bullet, I believe.

There is no explosion in a Gauss weapon as far as I'm aware. It depends whether or not the EM coils in the gun 'pulls' the projectile or 'pushes' the projectile out of the end of the rifle. If it 'pulls' the projectile, then 'recoil' would tend to pull the gun out of the owner's hands. The recoil calculators are for 'firearms' and wouldn't have any bearing on a gun of this type, I would think, except for the rocket rounds. The difference in size of a Gauss needle and the gun itself would probably tend to lose any inertia whatsoever. You're talking maybe a .01 gram needle pushing against a 10 kilogram gun - negligible. And if you have, say, 10 coils that accelerate the needle, each coil is going to impart inertia singularly, as the needle passes each coil, not all 10 at once.

I would say that shooting a Gauss weapon would be smooth as silk. When you add in the rocket rounds is when you would start to get recoil.

Just my .02Cr

Dameon
 
There is no relevant distinction to be made between 'pulling' and 'pushing'; in either case, the bullet is being accelerated by the gun, and therefore when the bullet moves forward, the gun has to move backwards.

A gauss rifle would, however, have a light recoil. The canonical 4g dart at 1,500m/s would have similar recoil to a .223 (for just the bullet, it's more, but once you count in the powder it's comparable).
 
Hmmm, you're right. I just pictured it as pushing or pulling something in water. The motive force still moves in the opposite direction. It's still not just the bullet that is moving forward in a firearm, tho. It's the propellant, and there is no propellant in a Gauss weapon.

4 gram needles? That's a nice size. How is that comparable to a bullet weight?

Dameon
 
A 4 gram bullet weighs about 62 grains, the same as the projectile of the 5.56x45mm M855 NATO. At 4mm (0.157), the gauss round is smaller in diameter than a BB (0.177 caliber).
 
When they say Gauss, I assume they mean coilgun. I think for a railgun, the recoil is more substantial.but I am not sure. And the notion of the whole thing being gravatic came from D20 furture where there is a gravatic railgun, not an electromagnetic one. Not that this gets around momentum, but hey id we can control gravity, we can control recoil.
 
Just another thought on the whole silent and no recoil issues, I'm not even sure you'd really want a combat gauss weapon to be either silent or recoiless.

Think about it, there you are in the field, a firefight raging, and you working the trigger, but you're not hitting anything. Why?

Because your weapon has jammed, but hey the quiet and no recoil feels the same on full auto or full jam.

Or maybe you burned through your clip and should be changing it but hey for the last several seconds you've been firing nothing because the weapon feels and sounds the same when you're firing needles or nothing.

Or maybe you forgot to disengage the safety but again, your senses are fooled because there is no difference between firing and not.

The above are very good examples of why you will probably want to keep a little felt recoil and audible sound.

Oh sure, somebodies going to say "Well, we'll just put a digital readout on the weapon and the hud that shows the weapon state." More information for the soldier to process is not always the best thing, especially when something this basic (am I shooting) is so easy to do the old fashioned way. It's not like once you're in a firefight that sound is going to give you away, and the managable recoil is never a problem either, except in zero-g maybe, and then you probably have bigger problems.

I think they found the same thing with early fly-by-wire and had to add active feedback circuits to simulate the usual force feedback on the control sticks and pedals so the pilots could tell from feel how the aircraft was performing.

I know I find a huge difference in my road feel going from manual steering to power steering, power steering tells me less about how the car is responding to the road and I actually prefer (and miss) manual steering. If I could turn off power steering for all but parking (it's original reason for being invented iirc) I would.

Just a thought to ponder and perhaps discuss.
 
Dear Folks -
Originally posted by far-trader:
The above are very good examples of why you will probably want to keep a little felt recoil and audible sound.
All extremely good points, ft! And ones I hadn't thought of before.

There's something like that in naval vessels, too. Just imagine, you're all dressed up in your anti-flash fire-retardent gear, with gloves that really do give you "fat fingers" so you can't operate an ordinary keyboard.

Instead, you use a reconfigurable (to run various devices) control panel, with holes instead of keyboards. You push your finger into the hole and it breaks a beam of light, letting the computer know a button has been "pressed".

Hoever, the designers encountered the same problem you mentioned above - no force-feedback to tell you that you successfully pushed your finger far enough down the hole to break the light beam. So the designers ended up putting totally non-functional buttons at the bottom of the holes, just so you know (by pressing them) that you're really "punching the keys"!!

As for silent/non-silent, I can only let you know what I read from GDW (shown earlier in this thread) that a weapons designer believed it was possible. The point is to make the displaced air around the projectile come back together without making a thunderclap. Hey, I know if I were a sniper, the idea of a silent weapon is great! See the Spooktek weapons on my site, all published in Challenge. Silent shotgun, silent pistol, etc - admittedly all close-range, subsonic weapons - and available to today's military, let alone that of TL 12!!!

Feh. You could always say it's like a laser, only quieter. "You hear a slight ripping sound, like someone quietly tearing a bit of paper. Then you start wondering, 'Where's Frank? He was standing right next to me a second ago! Frank? FRANK!'" etc etc.
 
Unless there is some sort of gravitic or other compensation, a gauss rifle will have recoil. A coil gun or rail gun firing the same projectile at the same velocity, and having the same mass, have exactly the same recoil energy.

Recoil is a function of weapon mass, projectiles mass and projectile velocity (in propellant weapons, you add propellant mass too). Calculating recol energy is very straightforward. This is very basic physics.

See http://www.travellercentral.com/rules/ke.html

Unless some theortical designs prove true, gauss weapons won't be silent either, at least if there's an atmosphere present. Even absent propellant, there's still ballistic crack.
 
They'd be pretty visible to RF detectors too; the currents and magnetic fields in a gauss weapon are quite strong, which will produce a rather distinctive electromagnetic pulse (the wavelength will be fairly long, making it hard to localize exactly, but it will be plenty detectable).
 
The barrel almost certainly is shrouded with some sort of cage, since it doesn't canonically kill every piece of electronics you're carrying when you fire it. As long as you have a hole for the bullet to come out of, you have a hole for at least some radio waves to leak out as well.
 
Gauss rifle recoil

I realize this is an old thread, but maybe someone's still interested.
I think most of the answers while good missed the real point. The gauss rifle will have significantly reduced recoil because the time over which the force is applied to the projectile is "much" longer. In a gunpowder weapon, the force is applied at the moment of and for the duration of the explosion, a very tiny time. In the Gauss rifle, the force is applied gradually for the duration of the time the round is in the barrel, still a fraction of a second but many times longer than the gunpowder explosion. Remembering F=Ma, the recoil from the same final velocity will be inversely proportional to the time required to accelerate to it. Haven't done the calculations yet, but if the acc time is 10 times longer then the "kick" will be 10 times less.
 
Storkje: Just remember that the force of the explosion actually lasts LONGER than the time the projectile is in the barrel; all firearms develop overpressure and have waste force in form of hot gasses ejecting. (That gas produces the muzzle flash. In some weapons, it's still burning as it exits, and in a few, it's recombusting as available O2 is already used up... such weapons are unpleasantly dirty...)
 
Well, the newest version of Mechwarrior core rules has a quote for the Zero G skill (paraphrased from not having it in front of me):

"Dammit, soldier! Gauss rifles DO have recoil!!!"
 
"Dammit, soldier! Gauss rifles DO have recoil!!!"
A .75 Recoilless, on the other hand, does not.

This is a handgun much used by Harry Harrison in some of his stories, capable of putting large holes into robots. He doesn't deign to explain just how the recoillessness is achieved, just implies that something with that caliber packs a punch far bigger than any handgun on Earth today.

Maybe it's a Gauss gun?


Hans
 
As the gauss weapons don’t loss energy with expanding gases (as told several times on this same thread), it’s to suppose that the same force applied to the ‘bullet’ is applied as recoil, not more not less.

If so, the acceleration applied to bullet and firer would be directly proportional to its weight. As the bullet is 4 gr and the firer about 80 kg, the acceleration the firer would receive a recoil would be about 20000 times inferior to that received by the bullet. If the bullet is propelled at about 1500 m/s, the firer would be thrown backwards at about 0.075 m/s, quite low a recoil, IMO.

What really I don’t understand about gauss weapons is that the bullet is said to be 4 mm 4 gr. Assuming it’s made of iron (7.87 gr/ml), it will be about 0.5 ml in volume. With a diameter of 4 mm (base area 0.1256 sq. cm), its length would be about 4 mm (if cylindrical, and I assume it's not hollow, as I know of no hollow bullets, though I'm not precisely an expert in weapons). Of course if made of heavier elements, lenght would be still less.

I find it quite small, as it has nearly the same caliber than length, and sure not to be called a needle…
 
What really I don’t understand about gauss weapons is that the bullet is said to be 4 mm 4 gr. Assuming it’s made of iron (7.87 gr/ml), it will be about 0.5 ml in volume. With a diameter of 4 mm (base area 0.1256 sq. cm), its length would be about 4 mm (if cylindrical, and I assume it's not hollow, as I know of no hollow bullets, though I'm not precisely an expert in weapons). Of course if made of heavier elements, lenght would be still less.

I find it quite small, as it has nearly the same caliber than length, and sure not to be called a needle…

I think your calculations have an error. From memory I had it pegged at 40mm long. Plugging the numbers into a handy weight calculator online* that comes to just about 4 grams as advertised. Or you took the bullet weight to be grains instead of grams?

* http://www.matweb.com/tools/weightcalculator.aspx

using: cross section of circle, steel for the material, 4mm diameter, and 40mm length
 
I think your calculations have an error. From memory I had it pegged at 40mm long. Plugging the numbers into a handy weight calculator online* that comes to just about 4 grams as advertised. Or you took the bullet weight to be grains instead of grams?

* http://www.matweb.com/tools/weightcalculator.aspx

using: cross section of circle, steel for the material, 4mm diameter, and 40mm length

You're right, sorry. I failed in units on the result (it was 4 cm, not 4 mm as I pointed). That seems quite more realist for me.
 
There was a discussion on this board somewhere (I haven't a hope of finding it, though it could be upthread here, I haven't checked) that suggested gauss 'needles' could be hollow tubes, as the aerodynamics of a tube reduces the supersonic boom.
 
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