Naval Railgun prototype undergoes first tests...

[Fumesucker]

http://www.gizmag.com/em-railgun-commences-firing/21644/?utm_source=Gizmag+Subscribers&utm_campaign=e3ab4a473c-UA-2235360-4&utm_medium=email

The electromagnetic (EM) railgun prototype launcher that was recently installed at the Naval Surface Warfare Center (NSWC) in Dahlgren, Virginia, has commenced firing, kicking off a two-month-long series of full-energy tests. Predictably, the first full energy shots make for some pretty impressive video.

Following its delivery by BAE Systems on January 30, the first prototype demonstrator was installed and outfitted with a suite of sensors, high-speed cameras and measuring devices to allow for evaluation of the 32-megajoule weapon.

Following a series of low-energy test shots, evaluation of the launcher is now underway and will see tests conducted at 20 megajoules to 32 megajoules - one megajoule is equivalent to a 1-ton object being thrust at 100 mph (161 km/h). Test projectiles similar to those previously fired from NSWC Dahlgren's laboratory launcher will be fired at speeds of 4,500 to 5,600 mph (7,242 to 9,012 km/h) using electricity instead of chemical propellants.

The U.S. Navy hopes the evaluation will help it reach its near-term goal of a 20- to 32-megajoule weapon for surface ships capable of shooting a distance of 50 to 100 nautical miles (57 to 115 miles/93 to 185 km).

[rfranklin]

1. Oh boy, now everyone can hunt for sustenance!

This will help feed the masses!

[Evasporque]

2. We rock at creating things to mash people into goo....nt

[tularetom]

3. Pretty cool

Wish we were as good at coming up with ways to cure, feed and house people as we are with ways to vaporize them.

[L0oniX]

4. Jobs.

[denbot]

5. As an old tincan sailor, that's kinda cool..

Part of my job was plotting Naval Gunfire Support. Our destroyer's range was just over 12 miles.

http://en.wikipedia.org/wiki/5%22/54_caliber_Mark_42_gun

[Ready4Change]

6. What do you make of the wobble in the projectile?

This is newer footage than the last I saw, but the projectile still looks squared off, and emerges with a distinct wobble. Seems to me that bodes for very poor consistency in aiming at a distance?

[Motown_Johnny]

7. i think the wobble comes in after it blasts through the wall

not when emerging from the weapon, although it is kinda hard to tell with this footage.

Odds are this was also a low energy test that we got to see.

I am willing to bet that the shape of the projectile is the least of their worries. If they need something more streamline then they can create it easily.

[denbot]

10. The projectile is somewhat oddly shaped.

It has flat weighted head, narrow shaft, and a heavy notched base. I would imagine that the acceleration compresses the "shaft" portion, and when the projectile is released the decompressed rebound would cause a wobble.

This is more of a proof of theory prototype and the projectiles would have to be more aerodynamic the what we see here.

[TheWraith]

21. I think that that projectile is for safety in testing.

In this situation, since you're not taking 100-mile shots, you don't want something that has a high ballistic coefficient, so it's not likely to get away from you or ricochet.

[Motown_Johnny]

8. Lets have some fun with this

Last edited Thu Mar 1, 2012, 12:01 AM - Edit history (1)

Earth's escape velocity is ~25,300 mph. That 32 megajoule weapon can fire a one ton projectile at 3,200 mph. So, half a ton at 6,400 and a quarter ton at 12,800 and an eighth of a ton at 25,600 mph.


That means that the 32 megajoule gun could launch something that weighs over 250 lb into orbit. Not very useful for anything living or delicate, since the G forces from the launch would be enormous, but for small payloads this might be an actual start. It might even be a way to help resupply the space station so you wouldn't need heavy lift rockets for supplies and tools. If they can increase the strength of the gun in later models then we might be launching 1 ton at a time without the use of chemical propellants in the near future.

See... Fun!

[Hugabear]

9. Or shooting down enemy satellites

Just sayin'

[Motown_Johnny]

11. less fun

but true

[JSnuffy]

25. Depends on your definition of fun...

... I like both.

[denbot]

12. An orbiting launcher could launch probes and even supplies to far flung outposts

Heavy supplies like water, propellent, or building supplies could be launched in to orbit with a rail, and with another orbiting rail, the same objects to be launched to their true destinations.

Most technological advancements started as military applications.

[Motown_Johnny]

13. For every action......

An orbiting launcher would have a "recoil" (roughly) equal and opposite to the force launching the payload.

You might still be able to do it but it would have complications that a ground based rail gun would not have.

[TheWraith]

16. Similar ideas have been in the ether for a long time.

Going back at least as far as the 1960s, there's books that have postulated the idea of using magnetic acceleration "catapults" which function basically the same as this as a cheap means of launching things to orbit. You'd have to have a very large one, though, if you wanted to launch anything of useful size at a speed which wouldn't turn the contents--say, people--into pulp. But you're right that a smaller version could theoretically be used for supplies, or even for small solid-state satellites which can be assured of surviving those kinds of G forces.

Ironically, in Heinlein's "The Moon is a Harsh Mistress" the process we see here is kind of reversed; a mag launcher designed for cargo shipping is actually ad-hoc converted into a missile launcher. Albeit using 100 ton missiles.

[Motown_Johnny]

18. This is the first practical working model that I am aware of

give it 50 years


You may see some robotic version of the space shuttle that is first lifted by a rail gun but then uses chemical rockets to adjust it's own vector and speed in order to deliver a payload to orbit and then glide back to earth.


It wouldn't surprise me a bit.

[TheWraith]

20. This is the first working on on this scale, sure.

They've been built on smaller scales for a long time, it's just that big ones cost big money.

As far as launching payloads, first I suspect we'd see payloads with disposable rocket packs to adjust the vector; it's often cheaper to throw some parts away than it would be to build a specific purpose vehicle. Case in point, the Russians have actually been known for executing cheaper space missions using disposable rockets than we have with the shuttle. Besides, the less complexity there is, the more of the weight limit will be available for the payload itself.

[Motown_Johnny]

22. True

but the smaller ones (that I am aware of) have only been launching small bullet like projectiles, nothing like this.

and a shuttle style vehicle would have the advantage of being able to retrieve payloads, plus there wouldn't be any space debris from discarded rockets. The idea behind the space shuttle was for it to be less expensive in the long run. That didn't work out but the theory is still valid.

[krispos42]

19. Here's the problem

That escape velocity depends on there being no air on the earth. Since we do have air, we'd have to do something about that. Otherwise you have a projectile scorching through the atmosphere at Mach 34.

Instant incineration of the projectile aside, it would also soak up a lot of speed during the several seconds or more it would take to reach the atmosphere. Which would necessitate a higher launch velocity...

Now, if we built one someplace high up, in Colorado or something, that would put a big chunk of the atmosphere behind the projectile. Plus, we could build it up the side of a mountain.

Hmmm...

[Motown_Johnny]

23. minor details

and that escape velocity did not include the Earth's own momentum in the calculation.

I'll admit that the atmospheric friction is a problem but it can be overcome. I have lived in Colorado at altitudes above 8,000 and even worked at a couple places above 10,000 ft. There is still air. You can cut 1 or maybe even 2 miles of atmosphere out of the equation but that is about all. You would also want to be able to aim the gun toward the orbit you needed so running up the side of a mountain might not be practical.



http://sbir.nasa.gov/SBIR/abstracts/04/sbir/phase1/SBIR-04-1-X2.06-7680.html

^snip^

POTENTIAL NASA COMMERCIAL APPLICATIONS (LIMIT 100 WORDS)

The material developed during this Phase I effort will have a variety of applications in the aerospace industry, and within NASA specifically. Aerogels are the most efficient thermal insulation known, and NASA has several applications that would benefit from the low density and thermal conductivity of aerogels. Among these are replacements for the flexible ceramic blankets, and low-temperature ceramic tiles on the Space Shuttle, as well as replacements for fibrous insulation within the metallic TPS (ARMOR concept). Composites developed on this program will be utilized in the heatshield designs for the spacecrafts undergoing aerocapture or aerobraking maneuvers



OK ok, low temperature ceramic tiles.... but they haven't tried to adopt it yet.

[krispos42]

27. Even going up the side of a mountain isn't particularly steep.

I mean, if you average it over a couple of miles of railgun.

Let's say you get a 10% grade, exiting the railgun at about 10,000 feet altitude. You'd be running close to tangential to the earth's surface and parallel to the equator, which is pretty much where you want to be for a stable orbit. As opposed to straight up, which would be more for interplanetary travel.

You'd just have to be moving really really fast. You'd basically be moving horizonally fast enough to make the earth drop out from underneath you. However, some sort of small wing might drastically increase lift, enabling the spacecraft to gain altitude faster and thus get out of the thicker air sooner.

The problem is the length of the gun we'd need.

Low earth orbit is about 17,000 mph; 1g of acceleration is about 22 mph per second; we'd need nearly 13 minutes and 1,800 miles of railgun to get up to orbital speed!

Punching it up to 10 g's, we'd need only 77 seconds and 181 miles of railgun, but that would be awfully hard on a person's body.

100 g's gets us 7.7 seconds and 18 miles of railgun. And corpses in the passenger compartment, but that's not too bad for cargo.

1000 g's works out to .77 seconds and 1.8 miles of railgun, but the passengers will be chunky salsa.


Hmmm... it might be that we could use a railgun to get a scramjet aircraft up to speed. Punch it up to Mach 5 and let the scramjets start up.

You'd save a huge mass of fuel starting from 10,000 feet and Mach 5 versus sea level and motionless for a conventional rocket.

[JVS]

26. We can use it to send up building supplies for Newt's moonbase!

[Zanzoobar]

14. Green death

It's electric. They shoudl be able to run it off solar power at some point. It's all the rage.

[greytdemocrat]

15. Very cool.

Well done BAE.

[slackmaster]

17. Proud National Railgun Association member checking in!

My home library sports more than 30 years' back isses of Scientific American Rifleman.

[pokerfan]

24. Will Rogers said it best

"You can't say that civilization don't advance, however, for in every war they kill you in a new way." —Will Rogers, New York Times, 23 December 1929