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Operate railgun at high voltage low current?

04/21/2022 2:15 AM

Current serious research in railgun operates it at currents of a million ampere and voltage around orders of 1000 volts.

Is it possible to design an experimental railgun that operates at high voltage, but low current. We would ignore the achievable muzzle velocity. Let's assume our source is a capacitor bank charged to 100 kV and the average discharge current target is 10,000 A. Can such a railgun be built.

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#1

Re: Operate railgun at high voltage low current?

04/21/2022 7:12 AM

Of course you could build one.

Perhaps the appropriate question to ponder is why do the scientists and engineers that are experts in the field not do it that way.

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#3
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Re: Operate railgun at high voltage low current?

04/21/2022 8:48 AM

I seem to have come to an answer myself. It cannot be done.

For a fixed total resistance R of the rails and the armature, current I = V/R which means a voltage of 100 kV would generate a current so high that it would immediately destroy the rails. Currently, even 1000V/R is giving a current in the order of a million ampere! So a railgun cannot be designed to operate at high voltages beyond what range it is now conventionally using.

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#2

Re: Operate railgun at high voltage low current?

04/21/2022 8:38 AM

Is it possible to design an experimental railgun that operates at high voltage, but low current.

I don't see how. A railgun uses magnetic forces to accelerate the projectile, and magnetism is created by current and the more current the more force. The projectile is forced down the rail by an interaction between the current through the projectile and the magnetic field generated by the current through the rail.

It is possible to accelerate charged particles with an electric field (high voltage) but the forces created by an ion engine are magnitudes smaller than magnetic propulsion.

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#4

Re: Operate railgun at high voltage low current?

04/21/2022 8:54 AM

Maybe a hybrid that uses conventional explosive and an electromagnetic booster...could be possible I guess....

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#5
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Re: Operate railgun at high voltage low current?

04/21/2022 2:55 PM

With a sufficiently long barrel,or rail,it could be accelerated in steps,like a mag Lev train,by sequentially energizing coils along the length; a linear accelerator.It will still require the same amount of energy to accelerate an object to the same speed,but the instantaneous spike of power demand could be avoided,but this approach has probably been tried and failed for practicality reasons.

Maybe a circular tube to increase length of the tube and give time for the projectile to accelerate,or course then you encounter the problem of keeping it off of the sides of the tube.

There are many very intelligent specialists working on this problem as we speak.

The current problem(pardon the pun) as I see it,is sufficient energy storage to fire the weapon,and time between charges of the super capacitors.

It is like trying to store the lightning of an entirre thunderstorm in a thimble,and releasing it at will.

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#6
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Re: Operate railgun at high voltage low current?

04/21/2022 3:26 PM

If I remember my history correctly, there was a cannon design that attempted to time explosions along the barrel to increase velocity, it failed because of no support for back pressure...I'm thinking that you could try the same design with an electromagnetic pulse timed to close the barrel behind each explosion...would have to work out the details, but the timing seems doable...what do you think?

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#7
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Re: Operate railgun at high voltage low current?

04/21/2022 3:51 PM
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#8
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Re: Operate railgun at high voltage low current?

04/21/2022 4:25 PM

The problem may be finding a valve that is fast enough.A piezo valve?

Why not a series of coils along the barrel,as i n my previous post?

There is a cannon that fires 1 million rounds a minute,and it is fired electronically,with the previous round making it easier for the next round to fire,before the round ahead even clears the barrel.

https://www.youtube.com/watch?v=wKlnMwuCZso

Here is a link on that same page to the rail gun:

https://www.youtube.com/watch?v=58MmOpSm4LY

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#9
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Re: Operate railgun at high voltage low current?

04/21/2022 10:56 PM

Maybe a bullet that shoots another bullet and then that bullet shoots another bullet....It starts bigger and shoots smaller and smaller bullets each subsequent bullet increases in velocity...

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#10
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Re: Operate railgun at high voltage low current?

04/22/2022 7:45 AM

With a sufficiently long barrel,or rail,it could be accelerated in steps,like a mag Lev train,by sequentially energizing coils along the length; a linear accelerator.

I think what you're referring to is a "coil gun".

"Rail Guns versus Coil Guns

A coil gun (or Gauss gun) is an electromagnetic launcher that offers a few advantages over rail guns. The "barrel" of a coil gun is a series of copper coils. These coils are energized sequentially, setting up a traveling magnetic field on the inside of the barrel. This magnetic field attracts a ferromagnetic projectile down the barrel. Since the projectile of a coilgun floats in the barrel and never touches the coils, it suffers less wear and tear, and these guns are completely quiet. Coil guns have been demonstrated to supersonic velocities, but they are not as efficient or as capable as railguns."

https://science.howstuffworks.com/rail-gun2.htm

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#11
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Re: Operate railgun at high voltage low current?

04/22/2022 8:42 AM

Thanks for the info.I still wonder why the speed cannot be accelerated to the same as a rail gun,if given sufficient length.Efficiency is usually not a factor when making weapons for war.Artillery barrels have to be replaced frequently.

The problem with a rail gun is the instantaneous energy required to accelerate the mass to max speed in a millisecond or so.It would seem that if the rate could be spread out over more time,as in a coil gun,it would be easier to implement.Perhaps several steps instead of one hard kick?

Since the projectile never touches the barrel in a coil gun,it could be made circular to optimize space.

Perhaps the projectile could be fired in an evacuated barrel(Vacuum)to reduce heat during travel down the barrel.?

A side note on instantaneous energy:A shotgun shell,at the Instant Of Firing,produces more energy than all of the power plants on Earth in that brief interval. I have no idea how much energy is produced firing a 16inch naval gun.

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#12
In reply to #11

Re: Operate railgun at high voltage low current?

04/22/2022 9:52 AM

Quote: "A side note on instantaneous energy:A shotgun shell,at the Instant Of Firing,produces more energy than all of the power plants on Earth in that brief interval."

I don't think I could buy this however you define "instantaneous energy". Energy = power x dt. So how "infinite" could the instantaneous power be?

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#14
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Re: Operate railgun at high voltage low current?

04/22/2022 4:25 PM

Gun length would be a consideration for a coil gun if it is mounted onboard a ship and needs to be maneuvered for aiming. And I think bending it in a circle would be out of the question due to centrifugal force.

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#15
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Re: Operate railgun at high voltage low current?

04/22/2022 5:26 PM

Maybe you could aim it with spin, like a golf ball...?

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#13

Re: Operate railgun at high voltage low current?

04/22/2022 10:18 AM

This might be what you are looking for. They also launch aircraft from carriers using a similar Linear Motor aircraft launch system

Navy to unveil railgun in San Diego

Star Wars-like weapon will be on public display at Naval Base San Diego in July

By Jeanette Steele6 a.m.April 7, 2014

This summer, San Diego will host the public unveiling of a military weapon that the Navy’s chief scientist calls a Star Wars-like technology that is nevertheless now viable.

In July, the Navy will hold a static display of its $500 million electromagnetic railgun prototype program at San Diego Naval Base, aboard the Joint High Speed Vessel Millinocket. It’s the same ship on which the Navy will perform the first maritime firing test of the weapon in 2016.

“The American public has never seen it,” said Rear Adm. Matthew Klunder, chief of naval research, in a recent telephone press conference.

“Frankly, we think it might be the right time for them to know what we’ve been doing behind closed doors in a Star Wars fashion,” he said. “It’s now reality. It’s not science fiction. It’s real and you can look at it.”

Railguns use an electromagnetic force -- known as the Lorenz Force -- to launch a projectile between two rails. A high-power electric pulse is delivered to the rails, where a magnetic field is generated.

The result: A 23-pound projectile can be hurtled at speeds up to Mach 7 and travel more than 100 miles. And the cost of each projectile is about $25,000. That’s 1/100th the price a conventional missile, Klunder said.

Navy officials have been discussing the railgun as an exciting future capability for some time, and the prototype program officially began in 2005. Between 2005 and 2011, the Navy spent $250 million on the effort, and officials say they expect to invest the same amount between 2012 and 2017.

Klunder described the weapon as a game-changer whose time is just about here.

In 2016, the Navy will test the single-shot capability of one of its two prototypes, made by San Diego-based General Atomics and BAE Systems.

Officials chose the Millinocket -- a noncombatant catamaran intended for cargo and troop carrying -- because its broad flight deck has plenty of space for the weapon, which consists of the gun mount, power supply and three other major pieces.

In July, the Office of Naval Research awarded a $34.5 million follow-on contract to BAE for a multiple-shot prototype that will conduct its first shipboard firing tests in 2018. That prototype will incorporate auto-loading of projectiles and technology to manage the heat generated by the power required.

The following year, the Navy would begin studying how to integrate the weapon onto ships.

“I really think it will give our adversaries a huge moment of pause to go, ‘Do I even want to go engage a naval ship?’ Because you are going to lose. You can throw anything at us, and the fact that we can shoot a number of these rounds at very affordable costs -- it’s my opinion that they don’t win,” Klunder said.

Current Navy destroyers and cruisers have between 96 and 122 vertical firing tubes for launching Tomahawk and other missiles. In comparison, each railgun could be accompanied by hundreds of projectiles, Klunder said.

“Your magazine never runs out,” he said.

The technical issues surrounding railguns have been tied to the power needs.

The current prototypes are producing 32 megajoules of power. Klunder said that’s enough to propel a projectile so that it goes through a ship hull or an airplane skin “like a freight train.”

In March, the Navy’s top officer testified before Congress that “that high of energy that is generated through there can tend to melt the barrel” of the gun, which added to other reports that the weapon has experienced difficulties with overheating.

“We have to get the right barrel and do that right. We're working that, and the engineers tell me, ‘No, we can do this,’ ” Adm. Jonathan Greenert told the House Armed Services Committee on March 12

Klunder last week said it’s not a problem but something they will watch as the multiple-shot prototypes get underway.

“We have fired this gun hundreds of times, and that is not an issue,” he said.

The Navy has test-fired the prototypes on land at the Naval Surface Warfare Center in Dahlgren, Va., and at New Mexico’s White Sands Missile Range.

Officials are looking at the possibility of making the projectiles guidable once they leave the gun barrel and of using rounds containing high explosives, among other kinds. But no decisions have been made.

Naval analyst and historian Norman Friedman said adding explosive power would make the railgun a much more lethal weapon. He used the example of targeting a tank.

“There are a lot of things used to hit tanks. In some cases, the thing is going so fast it makes a hole in one side and a hole in the other side, and if you don’t happen to be standing in the way, you never know you got hit,” said Friedman, a physicist and author of more than 30 books.

“Other things, you get hit and it basically blows up.”

However, Friedman added, the relatively unlimited magazine of the proposed railgun would make it a considerable weapon, aside from the question of whether it can blow stuff up.

The videos for the Rail Gun and Aircraft launches are really impressive.

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#16
In reply to #13

Re: Operate railgun at high voltage low current?

04/23/2022 11:51 AM

The railgun works for "shock and awe" but is apparently not a long enough range for present day threats.

https://www.popularmechanics.com/military/weapons/a36633707/us-navy-railgun-is-finally-dead/

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#17

Re: Operate railgun at high voltage low current?

04/24/2022 12:31 PM

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#18
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Re: Operate railgun at high voltage low current?

04/24/2022 12:53 PM

skip to 5:00

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