BF2S Forums US Navy tests railgun

Last edited by LaidBackNinja (2007-01-18 10:52:03)

LaidBackNinja wrote:

You meant E=0.5MV²
Energy= 0.5 times Mass times Velocity square
This shows that the velocity of your projectile is much more important than its mass.

max wrote:

LaidBackNinja wrote:

You meant E=0.5MV² (this is the formula for KINETIC energy, the one you want)
Energy= 0.5 times Mass times Velocity square
This shows that the velocity of your projectile is much more important than its mass.

energy is dependent on acceleration and mass not speed. a bullet in space that goes with 100000 km/h has absolutely no energy

max wrote:

Paco_the_Insane wrote:

max wrote:

energy is dependent on acceleration and mass not speed. a bullet in space that goes with 100000 km/h has absolutely no energy

no. its velocity. go take a physics course.

i did and the moment i posted i realised that i said bullshit. thats why i deleted it

i was thinking about force

spray_and_pray wrote:

LaidBackNinja wrote:

You meant E=0.5MV²
Energy= 0.5 times Mass times Velocity square
This shows that the velocity of your projectile is much more important than its mass.

Thats the one I wanted thanks.

LaidBackNinja wrote:

spray_and_pray wrote:

LaidBackNinja wrote:

Kilojoules is waaay too much for small arms. A BB gun typically produces between 0.5 and 1.5 joules.

The test rail gun fired 8 kilojoules im sure BB guns use much much less.

Do you maybe mean the final energy produced by the weapon? As in the projectile it fires? If I calculated correctly a rail gun that can fire a projectile at 10 000kmph should produce 750K kilojoules with the projectile. However the actual rail gun only produces 35 kilojoules itself.

First of all, you are talking about a ship mounted railgun here. A railgun carried by infantry should be nowhere near this power output. Also in your calculation, what mass did you use for the projectile?

Last edited by spray_and_pray (2007-01-18 11:28:06)

Eugefunk84 wrote:

Flecco wrote:

For anybody who understands more about technology, physics, electronics and weaponry than me...

What are the chances of the technology being made handheld and being used by footsoldiers practically?

I'm an electrical engineer and have studied the effects that cause a projectile to be shot out of a railgun. It's a fundamentally simple device, utilizing only electrical currents to move a projectile. This effectively makes for zero recoil, also. However, the power needed to fire a projectile the size and mass of a standard bullet at comparable speeds greatly exceeds anything that can be carried by a foot soldier. Also, since you need a very precise pulse generator to keep the projectile accelerating down the rails, this would make for some extremely heavy electronics.

So, bottom line is that you should not expect to see this carried by foot soldiers, until we figure out a way to create portable nuclear energy pretty much. If you have any more specific question, PM me.

Funk

Eugefunk84 wrote:

IsaacLeavitt wrote:

spray_and_pray wrote:

Very little it uses 35 kilojoules instead of 9 kilojoules used by Battleship artillery. Such a weapon would blow any soldier back and possibly kill them. Not to mention its weight. In a few years if we can advance the tech its very probable.

to fix the problem for infantry you could use high power capacitors that would be charged at a powerful energy source... these would then be used as ammunition in the portable railgun ... and to fix the recoil you could have the armature "blow back" when it reached the end of the "barrel" instead of stopping, causing an opposite force reducing the recoil greatly...

anybody catch my idea?

btw- railguns have a slightly parabolic range of fire... like a sniper rifle, exept way more powerfull...

Railguns have no recoil. There is no explosion contained behind the projectile to propell it out of a barrel, therefore there is no explosion pushing the actual gun in the opposite direction. As far as your capacitor ideas, it wouldnt work. In order to store that much charge, you would need way too many capacitors. Think about this, you ever see those huge car audio capacitors? Those store 12 volts, and deliver about 10 amps of current. Power=Voltage*Current, which in this case equals 120 Watts. This is not even close to enough power for a rail gun. So you would need to carry hundreds if not thousands of these comparably large caps to provide power for a shot, and on top of that, it would only be good for ONE shot, absolutely not practical. Railguns will always be subject to a massive power supply, such as those found on warships. It will probably never be available for foot soldiers.

Eugefunk84 wrote:

spray_and_pray wrote:

Eugefunk84 wrote:

Railguns have no recoil. There is no explosion contained behind the projectile to propell it out of a barrel, therefore there is no explosion pushing the actual gun in the opposite direction. As far as your capacitor ideas, it wouldnt work. In order to store that much charge, you would need way too many capacitors. Think about this, you ever see those huge car audio capacitors? Those store 12 volts, and deliver about 10 amps of current. Power=Voltage*Current, which in this case equals 120 Watts. This is not even close to enough power for a rail gun. So you would need to carry hundreds if not thousands of these comparably large caps to provide power for a shot, and on top of that, it would only be good for ONE shot, absolutely not practical. Railguns will always be subject to a massive power supply, such as those found on warships. It will probably never be available for foot soldiers.

That is impossible according to newtons 3rd law ninja said it every action has an equal and opposite reaction if a bullet travels down a chamber at extremely high speeds its going to push back the weapon once it exits the chamber.

OK, ill concede, there is SOME recoil, but in negligibly small. In the case of a traditional gun/cannon, its trivial to see where recoil arises from. And in a crossbow, recoil comes from the tensile force of the taught string. When it is released, the middle of the string where the arrow is sitting comes flying towards the front of the bow, but it also pulls the bow back towards the end of the arrow. Thats where crossbow recoil comes from.

Now, in the case of a railgun, things are slightly different. There are three forces involved here. The electromagnetic force propells the projectile forward on the rails. The second force is that of friction, which is experienced by the slug grinding against the rails during its acceleration. This is assuming that the projectile doesnt "roll" down the rails, which would cause no friction, but would also cause for a lot of spin once the projectile exits the rails. The third force is that of air resistance in front of the projectile, which also slows it down.

Hence, the only two forces that could cause recoil are friction and air resistance. The force of friction can be calculated by finding the mass of the projectile and multiplying it by a scalar, say X, which is based entirely on the material of the slug. Seeing as the mass of a slug/bullet is very very small, the force slowing down the round would be miniscule.

Now, the main cause of recoil would be the air resistance in front of the accelerating projectile. As it travels down the rails, it builds up air pressure in front of the round, which will push it back. The only thing coupling this with the rails themselves is the force of friction. Hence, if the force of friction is small, the amount of force that the "gun" will experience is very small as well.


Funk

Eugefunk84 wrote:

spray_and_pray wrote:

Eugefunk84 wrote:

Railguns have no recoil. There is no explosion contained behind the projectile to propell it out of a barrel, therefore there is no explosion pushing the actual gun in the opposite direction. As far as your capacitor ideas, it wouldnt work. In order to store that much charge, you would need way too many capacitors. Think about this, you ever see those huge car audio capacitors? Those store 12 volts, and deliver about 10 amps of current. Power=Voltage*Current, which in this case equals 120 Watts. This is not even close to enough power for a rail gun. So you would need to carry hundreds if not thousands of these comparably large caps to provide power for a shot, and on top of that, it would only be good for ONE shot, absolutely not practical. Railguns will always be subject to a massive power supply, such as those found on warships. It will probably never be available for foot soldiers.

That is impossible according to newtons 3rd law ninja said it every action has an equal and opposite reaction if a bullet travels down a chamber at extremely high speeds its going to push back the weapon once it exits the chamber.

OK, ill concede, there is SOME recoil, but in negligibly small. In the case of a traditional gun/cannon, its trivial to see where recoil arises from. And in a crossbow, recoil comes from the tensile force of the taught string. When it is released, the middle of the string where the arrow is sitting comes flying towards the front of the bow, but it also pulls the bow back towards the end of the arrow. Thats where crossbow recoil comes from.

Now, in the case of a railgun, things are slightly different. There are three forces involved here. The electromagnetic force propells the projectile forward on the rails. The second force is that of friction, which is experienced by the slug grinding against the rails during its acceleration. This is assuming that the projectile doesnt "roll" down the rails, which would cause no friction, but would also cause for a lot of spin once the projectile exits the rails. The third force is that of air resistance in front of the projectile, which also slows it down.

Hence, the only two forces that could cause recoil are friction and air resistance. The force of friction can be calculated by finding the mass of the projectile and multiplying it by a scalar, say X, which is based entirely on the material of the slug. Seeing as the mass of a slug/bullet is very very small, the force slowing down the round would be miniscule.

Now, the main cause of recoil would be the air resistance in front of the accelerating projectile. As it travels down the rails, it builds up air pressure in front of the round, which will push it back. The only thing coupling this with the rails themselves is the force of friction. Hence, if the force of friction is small, the amount of force that the "gun" will experience is very small as well.


Funk

Last edited by Ilocano (2007-01-18 12:01:35)

Eugefunk84 wrote:

ghettoperson wrote:

Eugefunk84 wrote:

OK, ill concede, there is SOME recoil, but in negligibly small. In the case of a traditional gun/cannon, its trivial to see where recoil arises from. And in a crossbow, recoil comes from the tensile force of the taught string. When it is released, the middle of the string where the arrow is sitting comes flying towards the front of the bow, but it also pulls the bow back towards the end of the arrow. Thats where crossbow recoil comes from.

Now, in the case of a railgun, things are slightly different. There are three forces involved here. The electromagnetic force propells the projectile forward on the rails. The second force is that of friction, which is experienced by the slug grinding against the rails during its acceleration. This is assuming that the projectile doesnt "roll" down the rails, which would cause no friction, but would also cause for a lot of spin once the projectile exits the rails. The third force is that of air resistance in front of the projectile, which also slows it down.

Hence, the only two forces that could cause recoil are friction and air resistance. The force of friction can be calculated by finding the mass of the projectile and multiplying it by a scalar, say X, which is based entirely on the material of the slug. Seeing as the mass of a slug/bullet is very very small, the force slowing down the round would be miniscule.

Now, the main cause of recoil would be the air resistance in front of the accelerating projectile. As it travels down the rails, it builds up air pressure in front of the round, which will push it back. The only thing coupling this with the rails themselves is the force of friction. Hence, if the force of friction is small, the amount of force that the "gun" will experience is very small as well.


Funk

You get recoil to a small extent from paintball guns. Why wouldn't it be the same just on a much larger scale with this?

because paintball guns use the same principle as traditional guns, and expanding gas behind the projectile, railguns do not. BTW, u play PB? I'm the VP of the Umass Amherst Paintball Club, what kinda gun you shootin?