Future guns, what's after the Rail Gun in terms of projectiles?

[Mingon]

One of the major problems with barrels is that they heat up (obviously), and due to the condition of the enviroment the likelyhood is that one side is going to be heated and the other cooled either by sunlight or wind. This effects the straightness of the barrell, but by adding heating elements to both side you can straighten the barrel which helps accuracy alot. Composite barrells are also starting testing - I know I designed one

 

[maluckey]

Yeah, The barrel expansion is partially addressed in the TDS calculations used on the M1A2 MBT and the Palladin Weapon systems, but it sure would be nice to loose the tonnage if at all possible. I'd often thought of a hybrid design using electro/chemical/pressure tank, to help overcome the enormous energy to just accelerate the projectile for its first couple of millimeters. The pros loose sleep over it, but I muse how nice it would be to have an MBT weighing in at a svelte 50 tons, combat loaded.

 

[Mingon]

The problems with the composite is you cannot replicate the Swaging easily as with an all metal barrel. The design I worked on used a 15% wall thickness of steel and the rest composite wrapped with carbon fibre - worked OK

 

[kaizersose]

Mingon,
What materials did you use for your barrel (I work in a composite research lab--i get my kicks off this stuff).

 

[Mingon]

Mingon,What materials did you use for your barrel (I work in a composite research lab--i get my kicks off this stuff).

Couldnt tell you the exact spec, The materials lab were I worked used what they thought was appropriate all I know was that it was wrapped carbon fibre the exact composition they did not want let on (wierd people materials people ). It was a very quick job, I jus took an existing design offset all the extrernal dimensions by 85% and added in some radii and some 30degree chamfering.

 

[Smilin]

Originally posted by: f95toli
I think you are missing my point, I do understand the need to be prepared and so on.
My quetion was simply "When do you use a rail gun?", the original idea was to use rail guns to shoot down ICBMs but it turned out to be impossible, and there seems to be better weapons for "normal" warfare already so what is the point if developing the rail gun?
That is a technical question, not a political one.

The railgun is needed for the same things we need conventional guns for. Has been a battle going on for several thousand years between the "warhead" and the armor. We've done some really clever things with shaped charges and penetrators but for the first time in a long long time the armor has a chance of winning. The frontal armor (chobham) on an abrams can't be pierced right now...good for us but our enemies will soon have the same if they don't already. How are we going to pierce this armor? We've almost reached the limits in the amount of energy we can place on the target. You can increase the energy by increasing the weight of the projectile - not counting explosives you basically double the energy by doubling the weight. You can also increase the energy by increasing the velocity. If you double the velocity you *quadruple* the energy. This is where the railgun comes in. With no explosives involved you could shoot a projectile fast enough to not only pierce frontal tank armor, but pierce the whole tank!

What about for anti-air? We have conventional guns that will shoot 30 miles easily, why don't we use them instead of missles to shoot down aircraft? The projectiles are too slow. A plane could literally make a circle in the sky waiting on the bullet to arrive - you'd never hit it. How about getting popped with a railgun? Chaff and flares aren't going to help you much, you won't see any tracer rounds - you'll just suddenly have a nice clean hole all the way through your plane.

What about for infantry. If you could get a railgun small enough to be carried by a two man crew it would change warfare forever. Sandbags, Tank armor, bunkers...they might start making them out of butter just for the fun of it.

 

[f95toli]

OK. That was the answer I wanted. But I have two more questions

1) How much damage is done to an armored target? Since there is no warhead and the momentum of the "bullet" is so high it should just go straight through the target, unless you hit some critical component (or a person) a small hole should not cause that much damage, or?
Wouldn't a Hellfire missile or something else carrying explosives give more "bang for the buck"?

2) What is the maximum speed of the "bullet" at ground level (in air), there is obviously a limit due to the drag and the weight/area ratio. Doesn't this reduce the effectivness of a rail gun significantly?

 

[maluckey]

It's not about the delivered munitions in the case of APDS ammo. In fact, they have no attached ordinance. The delivery of the kinetic energy, an about a half a pound of depleted Uranium shrapnel at hypersonic velocity, along with superheated plasma, inside of 30 square feet of encased class B battle armor is usually sufficient to turn into hamburger/liquify/mutilate/cook any hapless human near it. It also ruins electrical and elctronic equipment.

There are theoretical "limits" to speed, but it's mostly a function of the mass of the launched projectile, and the type of armor it has to defeat, than that of absolute speed. There are head hurting formulas to use and all, but think of launching a house at one hundred miles per hour, or a bullet from a .223 caliber rifle at 2000 FPS. It's a no-brainer, which one requires more energy to get to the target.

 

[Smilin]

Originally posted by: f95toli
OK. That was the answer I wanted. But I have two more questions

1) How much damage is done to an armored target? Since there is no warhead and the momentum of the "bullet" is so high it should just go straight through the target, unless you hit some critical component (or a person) a small hole should not cause that much damage, or?
Wouldn't a Hellfire missile or something else carrying explosives give more "bang for the buck"?

Sure, it's might go straight thru the target but it's going to be messy. First that armor doesn't part without getting HOT and you're going to have shrapnel everywhere. It's called "spall" - all the liquid and fragmented armor that flies around ricochetting inside the tank...trust me you don't need an explosive to blow a tank. During the first gulf war our tankers found the kenetic energy rounds (no explosives) were far more lethal than the HEAT rounds that used explosives. Also the latest incarnation of the Hellfire missle you mention has two *downward* firing warheads on it. They are designed to pierce the top armor which is thinner and at a 90 degree angle to the impact (very important).

2) What is the maximum speed of the "bullet" at ground level (in air), there is obviously a limit due to the drag and the weight/area ratio. Doesn't this reduce the effectivness of a rail gun significantly?

[/quote]
There is a limit at which the projectile will begin to disintegrate in the airflow but the bullet would disintegrate due to launching forces first. As far as drag is concerned that's what makes a railgun so effective - you don't need a large, high drag round. The most effective round for both airspeed and penetrating capability is one that is very long but has a narrow cross section. It's unlikely that the projectile that comes out of a railgun is the one that actually hits the target - more likely it will be some sort of sabot where the launch component breaks and falls away leaving only a "dart" to travel at mach-whatever to target. It would look something like this.

 

[Mingon]

Where did you get that photo? I havent seen many of the tungsten Sabot's in the public domain. fyi they are fired at 1800-2200 m/s

 

[RayH]

I think the biggest problem with fired high speed projectile weapons is going to be simple physics. You need some way of dealing with the recoil. Might not be a problem when firing from a high mass object like a tank or battleship but becomes an issue when it needs to be portable. For example, unless those rail guns in Eraser weighed a couple hundred pounds, they should have sent the shooters flying though the air.

 

[grant2]

Originally posted by: BoogieQ
This is a link to a rail gun...

The author of this article is obviously a clever guy but i wonder what he was thinking during this experiment.

Obviously the first thing you've got to do right is time the magnetic pulse to occur at the optimum time after the projectile has been launched by the compressed air gun. Why didn't he work out that detail with a very small, non-damaging charge before moving onto the big attempts?

Unless I misread this article (very possible) the pulse was initiated too soon, and so the projectile was only being accelerated for a few inches. I don't know if this relates to his other problem of most of the projectile being disintegrated or welded to the rails.

Maybe i'm missing something? If I were in his place i'd start with small small charges and crank it up gradually to see how things work out.

 

[Smilin]

Originally posted by: grant2



Maybe i'm missing something? If I were in his place i'd start with small small charges and crank it up gradually to see how things work out.

If I had a working railgun I'm not sure if I would have the restraint not to try firing the thing at full blast at least once - kinda like how I always fire up a game of quake on a new system build before I get everything else going.

 

[wirelessenabled]

Originally posted by: f95toli
But again, who are you going to shoot at?

Of the things mentioned here, the "smart" bullet is probably the only weapon that could be usefull, rail guns will probably be useless (or at least not cost-effective) in coming conflicts.

Not true. Airplanes and their drivers are very expensive. If during the recent Iraqi conflict the US Navy had a large rail gun mounted on a vessel in the Persian Gulf capable of firing several hundred kilo projectiles 3-400 kilometres. That would have negated the use of manned aircraft in Southern Iraq. Would almost certainly have been much cheaper.

Taking a more global view, most of the "interesting" targets in the world are located within a couple of hundred kilometres of the ocean. That is the perfect scenario for rail guns.

As I understand it now, to get kill power you need speed and accuracy. Accuracy means electronics (GPS etc) and speed means acceleration. The engineering problem is how to get a guided projectile accelerated to sufficient speed without disintegrating. You can alter the equation by lengthening the rail, or by hardening the projectile to withstand the G forces both of which are surely being worked on currently.

 

[wQuay]

This could be a huge breakthrough in gun technology.

As for lasers, would coating the target in a reflective surface render the gun useless?

 

[Mingon]

Its just a muzzle brake further down the barrel, doesnt look of any use in any manned situation as the exhaust gases would be blasted back at the firer

 

[BoogieQ]

I think the biggest problem with fired high speed projectile weapons is going to be simple physics. You need some way of dealing with the recoil. Might not be a problem when firing from a high mass object like a tank or battleship but becomes an issue when it needs to be portable. For example, unless those rail guns in Eraser weighed a couple hundred pounds, they should have sent the shooters flying though the air.

Incorrect, there is no recoil on a Rail Gun as it is pushing the projectile out of the chamber using magnetics and there is no recoil effect... all of the 'recoil' is basically being put INTO the projectile, repelling it out of the chamber.


As for the question on it not being timed right and firing too soon and melting the projectile to the tracks, you will read near that part that he did not have the air cannon pumped up enough and it did not get the projectile moving fast enough hence the 'missfire' if you will.

An air cannon was being used to begin the travel of the projectile and the pulse would do the rest. Without proper timing the heat would be so great that the projectile would melt and get stuck to the rails inside.

If they made those guns for real they use in Eraser, you could fire off 100 rounds without flinching... it's akin to a spit wad shooter or blow dart gun.. does your head snap back when you blow the dripping spit wad at your best bud?

 

[Mark R]

Incorrect, there is no recoil on a Rail Gun as it is pushing the projectile out of the chamber using magnetics and there is no recoil effect... all of the 'recoil' is basically being put INTO the projectile, repelling it out of the chamber.

Lol. Of course there is recoil.

Newton's third law reads "For every action, there is an equal and opposite reaction."

The force acting on the projectile exerts an equal and opposite force on the rails. An interesting construction problem with rail guns is that the recoil can be so powerful that the rails can buckle unless sufficiently large.

Railguns have the ability to accelerate very small projectiles to very high velocities - this does allow significantly less recoil than accelerating a large projectile to a low velocity, while maintaing the same kinetic energy. It is the kinetic energy that most accurately predicts the destructive power, but projectile mass does determine penetration. A 0.1 g projectile at 10 km s-1 is unlikely to penetrate a brick wall, but a 1 kg projectile at 100 m s-1 probably will. Firing the latter, however, generates 100 times as much recoil.

 

[grant2]

Originally posted by: BoogieQ

If they made those guns for real they use in Eraser, you could fire off 100 rounds without flinching... it's akin to a spit wad shooter or blow dart gun.. does your head snap back when you blow the dripping spit wad at your best bud?

To a small extent, yes, most people don't feel it because accelerating a few grams to a few meters/sec velocity doesn't require much force.

 

[nycromes]

A rail gun would not be ideal for space as equal but opposite forces would cause a significant force to be put on the ship firing with the gun. A large amount of counter force would be needed or the firing ship would accelerate backwards just like the object being shot.

I do not know if lasers cause the same thing, but being that you are accelerating energy and not an object with mass, the force on the ship could be less.

 

[BoogieQ]

When the rail gun at the link I provided is fired in the video, there is no recoil. The gun doesn't flinch at all.

This was my basis for my conclusion. This is perhaps due, as you said the size of the projectile.

BUT, let me offer this.. since it is a magnetic discharge, your telling me that if there was no projectile in there and the gun was fired it should recoil? I don't think it would..

However, i'm no science major.. it just seems to me that there would be little to no recoil in a railgun design due to how the pulse works.

I'd like to be proven wrong though!

 

[Fencer128]

Originally posted by: BoogieQ
When the rail gun at the link I provided is fired in the video, there is no recoil. The gun doesn't flinch at all.

This was my basis for my conclusion. This is perhaps due, as you said the size of the projectile.

BUT, let me offer this.. since it is a magnetic discharge, your telling me that if there was no projectile in there and the gun was fired it should recoil? I don't think it would..

However, i'm no science major.. it just seems to me that there would be little to no recoil in a railgun design due to how the pulse works.

I'd like to be proven wrong though!

Forward momentum given to projectile --> Rear momentum given to gun --> Conservation of momentum (like how a rocket works)

Cheers,

Andy

 

[BoogieQ]

So why doesn't the rail gun in the link move when fired?

 

[Mingon]

Probably due to the weight of the gun in comparison to the projectile

 

[Fencer128]

Originally posted by: Mingon
Probably due to the weight of the gun in comparison to the projectile

Yep momentum is conserved. Heavy gun --> very small movement. Light projectile --> very large movement.

Cheers,

Andy