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2007-01-18 15:43:51
Bertster7
Confused Pothead
+1,101|7007|SE London

UON wrote:

Bertster7 wrote:

UON wrote:


I was thinking that the force would act outwards not backwards.... which it does, but they don't move so it pushes the railheads back onto the breach...
The force will act in the opposite direction to the direction the projectile is fired in.
Yes, in practice.  But it's not a direct relationship. If the sides weren't braced the rails would explode outwards and the projectile wouldn't move.
But isn't the force to accelerate the projectile electrically generated? There would be no typical explosive reaction, just the reaction to the muzzle velocity of the projectile.

https://upload.wikimedia.org/wikipedia/en/thumb/4/41/Railgun-1.png/340px-Railgun-1.png
2007-01-18 16:23:00
UON
Junglist Massive
+223|7079

Bertster7 wrote:

UON wrote:

Bertster7 wrote:

The force will act in the opposite direction to the direction the projectile is fired in.
Yes, in practice.  But it's not a direct relationship. If the sides weren't braced the rails would explode outwards and the projectile wouldn't move.
But isn't the force to accelerate the projectile electrically generated? There would be no typical explosive reaction, just the reaction to the muzzle velocity of the projectile.

http://upload.wikimedia.org/wikipedia/e … lgun-1.png
But look where the force comes from, the magnetic fields from the two rails are pushing onto (edit: actually, "passing through" would be better wording for what I mean) the projectile, and the current is being conducted from the positive to negative rail via the projectile.  It's the current passing through the magnetic field which generates the motion in a given direction, reverse the terminals and the projectile would fire the other way.  But look at the directions of the magnetic fields around the rails... opposite.  And we know what happens when two opposite magnetic fields are in close proximity.  Those fields would quite happily push each other apart through magnetic repulsion if there wasn't the bracing forcing the projectile to absorb the field and convert it to kinetic energy... explosions aren't limited to chemical sources

On the up side, the circuit would break as soon as the rails split apart, so they would only buckle outwards with the force of the repulsion at the time the break occurred, but it would be messy.  I wouldn't want to be standing next to it, anyway.

edit: my initial reasoning went along the lines of the recoil being absorbed into the magnetic fields, basically slowing down the spin on the generators at the other end if you would.  Which is actually good in theory, but in practice the force against the fields gets transfered back into the rails and turns to physical force at that point, not at the generator.


edit: and some of you may be thinking that if the recoil is actually originally outwards and not backwards, why not allow a little outward motion and put dampers either side of the rails to absorb the energy there... nice idea, but the circuit across the projectile would break if the rails moved outwards... and there would be serious arcing and massive heat (even more that otherwise) even if you managed to restrict outward movement enough to still allow the air to conduct the current across the gap....

Last edited by UON (2007-01-18 17:00:22)

2007-01-18 17:13:31
Bertster7
Confused Pothead
+1,101|7007|SE London

UON wrote:

Bertster7 wrote:

UON wrote:

Yes, in practice.  But it's not a direct relationship. If the sides weren't braced the rails would explode outwards and the projectile wouldn't move.
But isn't the force to accelerate the projectile electrically generated? There would be no typical explosive reaction, just the reaction to the muzzle velocity of the projectile.

http://upload.wikimedia.org/wikipedia/e … lgun-1.png
But look where the force comes from, the magnetic fields from the two rails are pushing onto (edit: actually, "passing through" would be better wording for what I mean) the projectile, and the current is being conducted from the positive to negative rail via the projectile.  It's the current passing through the magnetic field which generates the motion in a given direction, reverse the terminals and the projectile would fire the other way.  But look at the directions of the magnetic fields around the rails... opposite.  And we know what happens when two opposite magnetic fields are in close proximity.  Those fields would quite happily push each other apart through magnetic repulsion if there wasn't the bracing forcing the projectile to absorb the field and convert it to kinetic energy... explosions aren't limited to chemical sources

On the up side, the circuit would break as soon as the rails split apart, so they would only buckle outwards with the force of the repulsion at the time the break occurred, but it would be messy.  I wouldn't want to be standing next to it, anyway.

edit: my initial reasoning went along the lines of the recoil being absorbed into the magnetic fields, basically slowing down the spin on the generators at the other end if you would.  Which is actually good in theory, but in practice the force against the fields gets transfered back into the rails and turns to physical force at that point, not at the generator.


edit: and some of you may be thinking that if the recoil is actually originally outwards and not backwards, why not allow a little outward motion and put dampers either side of the rails to absorb the energy there... nice idea, but the circuit across the projectile would break if the rails moved outwards... and there would be serious arcing and massive heat (even more that otherwise) even if you managed to restrict outward movement enough to still allow the air to conduct the current across the gap....
No. Because the forces are different. Remember the right hand rule. The electric and magnetic forces will be at right angles to the direction the projectile is fired in. Only the kinetic energy will generate recoil. Which is the opposite direction to the force shown as F (the direction of motion of the projectile) in the diagram posted earlier.

https://upload.wikimedia.org/wikipedia/en/thumb/9/9a/RightHandOutline.png/180px-RightHandOutline.png

Last edited by Bertster7 (2007-01-18 17:16:18)

2007-01-18 17:14:48
stryyker
bad touch
+1,682|7146|California

Democracy, at 8 Megajoules.
2007-01-18 17:46:00
UON
Junglist Massive
+223|7079
TBH think about the DREAD I doubt that it would work.  I expect the 1963 home version of a centrifuge cannon from Popular Mechanics is about as advanced as that technology will get.

http://boingboing.net/images/electricbbcannonme4.jpg

There might not theoretically be recoil if both centrifuge and projectile are moving at exactly the same speed at the point of divergence, but certainly the sudden change in mass on the spinning wheel would kick... amounting to recoil... the weapon would be impossible to hold steady and aim, and it would never be able to get up to the speed required.  And if it did it would tear itself apart from the sudden imbalanced caused by the projectiles leaving at that rate.  Dubious when you actually think about it.  Might work at low speed as a non-lethal weapon, but actually reading the page (as opposed to just googling "recoilless weapon system" on something similar and posting the first link ) it's definitely not going to do anything they claim.
2007-01-18 17:55:13
UON
Junglist Massive
+223|7079

Bertster7 wrote:

No. Because the forces are different. Remember the right hand rule. The electric and magnetic forces will be at right angles to the direction the projectile is fired in. Only the kinetic energy will generate recoil. Which is the opposite direction to the force shown as F (the direction of motion of the projectile) in the diagram posted earlier.

http://upload.wikimedia.org/wikipedia/e … utline.png

http://en.wikipedia.org/wiki/Rail_gun wrote:

There are also forces acting on the rails attempting to push them apart, but since the rails are firmly mounted they cannot move.
Point your current finger in line with the current flow in the rails and you will see where the outward motion comes from.
2007-01-18 18:07:14
jonsimon
Member
+224|6921
The primary limitation of a rail gun is the material. The rails degrade quickly and the gun itself must be firmly assembled and durable.
2007-01-18 23:35:07
beerface702
Member
+65|7119|las vegas
me thinks military advisor's played a bit to much quake 2
2007-01-18 23:42:14
Pernicious544
Zee Tank Skank
+80|7126|MoVal So-Cal

beerface702 wrote:

me thinks military advisor's played a bit to much quake 2
And Mech Warrior 4
And Halo 2
And Battlefield 2142
And Warhammer 40,000
And Quake 4
And Mech Warrior 3
And Mech Warrior 2
Or he could realize the potential for a high-velocity gun that fires slugs for a lower cost and at longer ranges while providing more damage as well as shorter in-flight time.
2007-01-18 23:45:42
unnamednewbie13
Moderator
+2,072|7198|PNW

Bubbalo wrote:

unnamednewbie13 wrote:

Because they've been on the drawing board for such a long time. And with high accuracy, you don't need guidance.
You do if the target moves erratically.
That's why there's computer targeting. But even if you wanted to use such overkill hardware against a vehicle, an impact like that doesn't even have to be precise to stop a moving target. Also, I suspect that infantry and other "on-the-scene" assets will never be made completely obsolete.

Bubbalo wrote:

unnamednewbie13 wrote:

Let's just hope that they don't abandon their more 'conventional' cannons, in case of an EMP attack.
I suspect that these would be just as reliant as railguns on computer systems.
...but wouldn't rely on huge amounts of electricity to fire at targets within viewing distance.

Bubbalo wrote:

unnamednewbie13 wrote:

Check out 'The Moon is a Harsh Mistress' for non-splody projectiles in action.
Great.  Whilst we're at it, you can check out "Battletech" for information on FTL travel.
Are you slamming Robert Heinlein, or just recommending more sci-fi?

Last edited by unnamednewbie13 (2007-01-18 23:53:28)

2007-01-18 23:49:34
power9787
Member
+10|7008
dude i had that plan a electromagnetic fired gun small arm firing normal rounds with gunpowder since two years ago
these bastards military
i had i was 13to14 yr old
2007-01-19 02:12:44
spray_and_pray
Member
+52|6917|Perth. Western Australia

Eugefunk84 wrote:

spray_and_pray wrote:

Ilocano wrote:


But still negligible when you consider the weight ratio of the projectile versus the railgun.  Now, if you introduced superconductor projectiles into this equation, how much less recoil would there be?
It all depends on how much you would have to change all the other factors to get the superconductor projectiles point being it would still create recoil.

Now here is a thing to think about is it possible to create a weapon that can kill a person without it having to obey newtons 3rd law? It would have to be like some sort of a laser beam thingo. Heh too much thinking for 5 in the morning.
It is possible. Quantum mechanics overturned newtonian physics. Newtonian physics no longer apply when things become either extremely small, or extremely light. When it comes to lasers, which basically form a coherent beam of electrons of the same exact frequency/wavelength, you are dealing with photons. Photons are both very very small in terms physical size and are completely massless. Yes, PHOTONS HAVE ZERO MASS. This has been proven through calculation of string theory, and if you dont believe me, pick up a book called "The Elegant Universe". That said, lasers do not adhere to newtonian physics, so a laser woudl never be "pushed back" by the photons it emits.
Ive watched the whole entire series of elegant universe and guess what String THEORY there you have it its a THEORY and no one knows if it exists because its too SMALL to prove.
2007-01-19 03:01:23
Bubbalo
The Lizzard
+541|6987

unnamednewbie13 wrote:

Bubbalo wrote:

unnamednewbie13 wrote:

Because they've been on the drawing board for such a long time. And with high accuracy, you don't need guidance.
You do if the target moves erratically.
That's why there's computer targeting.
Except that if it's moving erratically it can't be targetted by a computer, because there's no pattern to follow.

unnamednewbie13 wrote:

But even if you wanted to use such overkill hardware against a vehicle, an impact like that doesn't even have to be precise to stop a moving target.
But if it doesn't hit the vehicle it is unlikely to damage it.

unnamednewbie13 wrote:

Bubbalo wrote:

unnamednewbie13 wrote:

Let's just hope that they don't abandon their more 'conventional' cannons, in case of an EMP attack.
I suspect that these would be just as reliant as railguns on computer systems.
...but wouldn't rely on huge amounts of electricity to fire at targets within viewing distance.
But they would still rely on computers to target.  Further, unless I'm much mistaken, EMP would have little effect on stored energy.

unnamednewbie13 wrote:

Bubbalo wrote:

unnamednewbie13 wrote:

Check out 'The Moon is a Harsh Mistress' for non-splody projectiles in action.
Great.  Whilst we're at it, you can check out "Battletech" for information on FTL travel.
Are you slamming Robert Heinlein, or just recommending more sci-fi?
I'm saying that a science fiction novel cannot be used to prove science fact.

Also, I've never read Heinlein, but based on what I've read about him, I may well dislike like his books.  So, you can also chalk it up as knocking Heinlein, I guess.
2007-01-19 03:38:37
unnamednewbie13
Moderator
+2,072|7198|PNW

Bubbalo wrote:

unnamednewbie13 wrote:

Bubbalo wrote:

You do if the target moves erratically.
That's why there's computer targeting.
aExcept that if it's moving erratically it can't be targetted by a computer, because there's no pattern to follow.

unnamednewbie13 wrote:

But even if you wanted to use such overkill hardware against a vehicle, an impact like that doesn't even have to be precise to stop a moving target.
bBut if it doesn't hit the vehicle it is unlikely to damage it.

unnamednewbie13 wrote:

Bubbalo wrote:

I suspect that these would be just as reliant as railguns on computer systems.
...but wouldn't rely on huge amounts of electricity to fire at targets within viewing distance.
cBut they would still rely on computers to target.  Further, unless I'm much mistaken, EMP would have little effect on stored energy.

unnamednewbie13 wrote:

Bubbalo wrote:

Great.  Whilst we're at it, you can check out "Battletech" for information on FTL travel.
Are you slamming Robert Heinlein, or just recommending more sci-fi?
dI'm saying that a science fiction novel cannot be used to prove science fact.

Also, I've never read Heinlein, but based on what I've read about him, I may well dislike like his books.  So, you can also chalk it up as knocking Heinlein, I guess.
aUm, there is. If you know what kind of vehicle it is, a computer can calculate where it could possibly be in the time it takes a barrage to hit, and fire at the particular spots in question. With the kind of impact you're talking about with railguns, the vehicle will likely be damaged, disabled or stopped even if there isn't a direct hit. Debris and damage surrounding it would prove to be obstacle enough. If it's in town, I don't think you'll be using big guns on it anyway. In fact, using big guns on it at all is overkill.

bHow on Earth do roadside bombs ever manage do do any damage, then...

cOh dear, dear. How did we ever manage to fight any naval battle without computers...

dUm, no. I wasn't using sci-fi to prove science fact. I was suggesting a great book with the non-splody objects you brought up. But if you're going to be biased against Heinlein before you even read any of his work, that's not my problem. There wasn't any reason for you to attempt the snappy Battletech comeback in the first place.
2007-01-19 06:30:35
iamangry
Member
+59|7071|The United States of America

UON wrote:

iamangry wrote:

3. ...

to whomever asked about portable rail guns:  The rail gun would not be an effective weapon against infantry because in a hand held version the ammunition would have to be very tiny, and the resulting damage to a body would be small.  The projectile would just go right through, which isn't very effective for killing people.  Most modern bullets either fragment or cavitate  once they enter the body, causing all sorts of internal damage.  Now it might be a good idea to try and mount it on a tank.
What about the DREAD?

http://www.military.com/soldiertech/0,1 … D,,00.html

(edit: reduce post side)
That's awesome, but see, it's vehicle based, so it can be heavy.  In order for a railgun to have a large ammo capacity and still be light enough for the soldier to carry, it would have to have light (so small) ammo.  That is simply because the battery for continued firing would be of significant weight.  Oh, and I have one problem with that article.  He mentions that it could be used in space because it has no recoil.  He must not know about satellites.  A big centrifuge spinning around produces a much worse type of recoil... angular recoil.  You'd have to have another object counter-spinning while the DREAD thing is firing, otherwise you'd mess up your satellite's alignment, which is very important.
2007-01-19 07:27:14
Ilocano
buuuurrrrrrppppp.......
+341|7093

SmkenRez wrote:

Any one know what a Glitter Boy is...........
Rifts
Here is a pic link for a Glitter Boy holding the rail gun that they are famous for.
http://en.wikipedia.org/wiki/Image:Glitterboy.JPG
Damn.  Is this game still going on?  I played this during the BBS days.  Pre web internet.  In any case, akin to the Walkers on 2142, you need a mech to handle such a weapon.
2007-01-19 07:57:57
Stormscythe
Aiming for the head
+88|6975|EUtopia | Austria
About all the discussions here about recoil and no recoil...

There will of course be a recoil - all those saying that Newton's laws don't apply here are simply wrong. The product of the projectile's mass [m(p)] and the projectiles velocity [v(p)] must equal the product of the gun's mass and velocity [m(g) x v(g)]. Now, we of course see that such a rail gun might weigh some more than a simple bullet, especially with the 'PSU' that has to be attached to the rail gun. (cables, I think, might be a bit thick to be isolated well enough).
Moreover, I don't think anyone would accelerate a bullet to that speeds in a short barrel. So, the longer the way to accelerate (the lower the acceleration), the lower the implied forces would be...
2007-01-19 08:03:52
Bubbalo
The Lizzard
+541|6987

unnamednewbie13 wrote:

aUm, there is. If you know what kind of vehicle it is, a computer can calculate where it could possibly be in the time it takes a barrage to hit, and fire at the particular spots in question.
Look up the definition of erratic, then get back to me.

unnamednewbie13 wrote:

With the kind of impact you're talking about with railguns, the vehicle will likely be damaged, disabled or stopped even if there isn't a direct hit.
Except that the damage is transmitted through the ground, wich:

a) Is hard to move, make the force required to do damage much, much greater

and

b)  Is the other side of vehicle suspension, which (depending on the vehicle) could well have an impact

unnamednewbie13 wrote:

Debris and damage surrounding it would prove to be obstacle enough. If it's in town, I don't think you'll be using big guns on it anyway. In fact, using big guns on it at all is overkill.
Yet the US routinely uses cruise missiles to attempt to take out distant targets.

unnamednewbie13 wrote:

bHow on Earth do roadside bombs ever manage do do any damage, then...
You remember the talk that we were having about splody-boom versus non-splody-boom?  A bomb has splody-boom.  And shrapnel.

unnamednewbie13 wrote:

cOh dear, dear. How did we ever manage to fight any naval battle without computers...
Oh, right, because you have a few Imperial-era Deadnoughts just sitting around waiting to be used, along with crack crews to use them.

unnamednewbie13 wrote:

dUm, no. I wasn't using sci-fi to prove science fact. I was suggesting a great book with the non-splody objects you brought up.
You used the book (science fiction) to demonstrate the fact (science fact)

unnamednewbie13 wrote:

But if you're going to be biased against Heinlein before you even read any of his work, that's not my problem.
Despite the fact that this has no relevance to the topic, I was merely pointing out that I'm in no rush to read him because there are enough books that I think I will like.

unnamednewbie13 wrote:

There wasn't any reason for you to attempt the snappy Battletech comeback in the first place.
Awwww, did pointing out the idiocy of using Sci-Fi as an argumentative assistant hurt your feelings?
2007-01-20 06:44:38
unnamednewbie13
Moderator
+2,072|7198|PNW

Bubbalo wrote:

unnamednewbie13 wrote:

aUm, there is. If you know what kind of vehicle it is, a computer can calculate where it could possibly be in the time it takes a barrage to hit, and fire at the particular spots in question.
aLook up the definition of erratic, then get back to me.

unnamednewbie13 wrote:

With the kind of impact you're talking about with railguns, the vehicle will likely be damaged, disabled or stopped even if there isn't a direct hit.
bExcept that the damage is transmitted through the ground, wich:

a) Is hard to move, make the force required to do damage much, much greater

and

b)  Is the other side of vehicle suspension, which (depending on the vehicle) could well have an impact

unnamednewbie13 wrote:

Debris and damage surrounding it would prove to be obstacle enough. If it's in town, I don't think you'll be using big guns on it anyway. In fact, using big guns on it at all is overkill.
cYet the US routinely uses cruise missiles to attempt to take out distant targets.

unnamednewbie13 wrote:

bHow on Earth do roadside bombs ever manage do do any damage, then...
dYou remember the talk that we were having about splody-boom versus non-splody-boom?  A bomb has splody-boom.  And shrapnel.

unnamednewbie13 wrote:

cOh dear, dear. How did we ever manage to fight any naval battle without computers...
eOh, right, because you have a few Imperial-era Deadnoughts just sitting around waiting to be used, along with crack crews to use them.

unnamednewbie13 wrote:

dUm, no. I wasn't using sci-fi to prove science fact. I was suggesting a great book with the non-splody objects you brought up.
fYou used the book (science fiction) to demonstrate the fact (science fact)

unnamednewbie13 wrote:

But if you're going to be biased against Heinlein before you even read any of his work, that's not my problem.
gDespite the fact that this has no relevance to the topic, I was merely pointing out that I'm in no rush to read him because there are enough books that I think I will like.

unnamednewbie13 wrote:

There wasn't any reason for you to attempt the snappy Battletech comeback in the first place.
hAwwww, did pointing out the idiocy of using Sci-Fi as an argumentative assistant hurt your feelings?
aJust because something in motion is erratic doesn't mean that multiple possible courses cannot be predicted, if said object is a known quantity.

bShort of a direct hit, destruction of a path or resultant debris (from impact) placed before the mover or one of its potential paths will stop or slow it down.

cNot my call. The efficiency of this practice (striking distant targets with overly-expensive munitions) has been called into question on numerous decisions.

dYou were the one that brought up 'splody-ness,' but projectile from a railgun will not require as much innate 'splody-ness'.

eJust what are you on about, my caustic friend?

fNo I didn't. I'm a reader. I enjoy recommending works of fiction. Other people enjoy reading works of fiction. Reject the suggestion if you want, but insulting me for it will get you nowhere.

gIt has relevance in that offhand, I suggested a science fiction book that talked about inert matter used as low-tech projectiles in a high-tech war. If that isn't related to the concept of railgun ammunition at all, then I don't know what is.

hCorrect me if I'm mistaken, but haven't you posted agreement with (and in) various "let's mature these forums up a bit" threads? Let's try to put a bit of that in practice, shall we? I suggest taking your baiting attempts somewhere else, lest you derail your own thread. If you have some sort of personal complaint against me, spill your guts in a PM, because I don't think anyone else is interested.

Last edited by unnamednewbie13 (2007-01-21 02:39:54)

 

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