Navy Tests Mach 8 Electromagnetic Railgun

hargrand writes "Wired magazine has a story and publicly released video of the Navy test firing of a 32 megajoule electromagnetic railgun: 'Reporters were invited to watch the test at the Dalghren Naval Surface Warfare Center. A tangle of two-inch thick coaxial cables hooked up to stacks of refrigerator-sized capacitors took five minutes to power juice into a gun the size of a schoolbus built in a warehouse. With a 1.5-million-ampere spark of light and a boom audible in a room 50 feet away, the bullet left the gun at a speed of Mach 8.'"

Comments

I've heard that before

[marcovanb]

I've heard that before "Rule Britannia, Brittania rules the waves...".

Re:I've heard that before

[KonoWatakushi]

While the defense budget is no doubt way out of control, this is not at all the sort of thing that worries me. It has no practical military value in the near term, and at least produced interesting results.

I'm more concerned about other high-tech anti-personel weapons or robots, that will inevitably be pointed at people, possible even at our own citizens before long.

Speaking of waste, and far more disturbing at that, take a look at what the anti-terrorism efforts have spawned. I really had no idea of the scale of it. Having this turned against our own citizens as the fascism ramps up is truly frightening.

Re:I've heard that before

[Jenming]

The energy is not the same, however, it might not be less.
When you launch with a rocket, the rocket accelerates throughout the journey, making the maximum in atmosphere speed lower.
If you launch with a railgun, it starts _really_ fast and then slows down until it hits orbit. The fastest part of this trip is done at the highest air pressure. Which is really bad due to the exponential increase in drag as you increase speed. You would also need to take into account the added weight of heat shielding.

The comparable amount of energy would be launching a rocket with one large explosion on the ground. I would imagine that many of the same problems would exist whether this was done with a railgun or a bomb. I would not assume that the energy used was less.

Now if you launched from the moon (or anywhere else without an atm) then the railgun would have energy advantages.

Re:I've heard that before

[Alef]

Which is really bad due to the exponential increase in drag as you increase speed.

Drag increases quadratically with regard to speed, not exponentially. People really ought to stop using the term "exponentially" to mean "more than linearly".

Re:Mach 8 to Orbit?

[Rakshasa Taisab]

Mach 8 = 2 722.32 m/s.

Escape velocity being 11.2 km/s, so the answer is no.

Re:Mach 8 to Orbit?

[Interoperable]

Escape velocity is the velocity required to leave orbit, not to maintain a stable orbit. Of course, low Earth orbit is about 8 km/s, so still no.

Re:Mach 8 to Orbit?

[sulimma]

If something is thrown or shot, the orbit will go through the point the shot was fired. You have a problem if that is on earth surface. Even if you are fast enough for a stable orbit you need a rocket to shift that orbit away from your starting point.

Re:Mach 8 to Orbit?

[Rockoon]

At a deceleration of a constant 10m/s^2, it would still take 270 seconds to stop going up (the deceleration would actually decrease the higher it goes, but I'm not accounting for drag.. so its a tradeoff) it will have an average speed of 1.35km/s.

Thats 270s * 1.35km/s = a height of 364.5km, so it could conceivably enter into the region we call 'low earth orbit' which is between 160km to 2000km.

I dont know where to begin to calculate the drag as it rises, so I wont bother to calculate the decreasing deceleration either.

Might be able to shoot down satellites .. or throw some stuff up for the International Space Station to catch (347km altitude at perigee)

Re:Yay!

[bcmm]

Submarines don't surface to launch ballistic missiles. They come near to the surface, communicate using an antenna on a small buoy, then launch from just below the surface. See this this pic from Wikipedia.

Re:Yay!

[gtall]

Well, the U.S. economy has a GDP of a little north of $14 trillion. The current defense bill is about $720 billion. And somehow this $720 is supporting a GDP of $14 trillion?

Incidentally, the U.S. deficit is about $1.4 trillion for FY2010 which ended Sept. 30. The total debt is about $14 trillion (no relation to the GDP number, the latter is per year, the former spans decades of financial mismanagement).

The rich, say the top 1% of the pop. pay approx 37 % of all the income tax in the country. The top 20% pay about 85% of the income taxes. The bottom 50% of the pop. pay no income tax.

It is important to have a sense of proportion, it can keep you from making unwarranted assumptions.

AC Is Idiot, But He Knows It.

[WED Fan]

The way I see it, there are several reasons why the USA would want to build Railguns:

- They have info that aliens exist and can come to Earth. - They have confirmation that someone (e.g. China, Iran, North Korea...) really plans to attack the Western World (or only the USA). - They are planning to conquer the World in the next 10-20 years. - Or they are really just being careful and making sure they can face the unexpected.

You're an idiot, but you know that right? You're list shows you have no real critical thinking skills beyond what you learned from apocolyptic comic books, movies, and video games, but that doesn't stop you from trying act like you have deep thoughts.

The reason I am assuming you know you're an idiot is because you post as AC and have that little scrap of pride.

Try this: They've been working on railguns for ages, as a launch system for ballistic missiles, manned spacecrapft, projectiles, and other purposes. Electronics and triggering systems from that research make their ways into other areas.

Also, you always want to make your systems portable, safer on home turf, and easier to handle.

"Safer on home turf." The problem with explosive delivery systems like cannons, rockets, and guns is that their is a risk of blowing yourself to smithereens. If you can eliminate that from projectile delivery, you become more effective.

Do try to use your brain.

Re:The video is cool, but...

[Ksevio]

Well according to the Washington Post article on it:

It streaked down range, generating a small sonic boom, and traveled about 5,500 feet before tumbling to the ground harmlessly.

So not all that interesting.