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back to article Rocket train smashes world land-speed record

It's been a big 24 hours for the US weapons-tech establishment in terms of making stuff go really fast. American war-boffins shot a railgun slug with ten megajoules of muzzle energy (and speed of Mach 7+) yesterday; a different weapons lab has also broken the world land speed record. The new benchmark - with reference to …

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Silver badge
Stop

Land Speed Record?

While impressive this isn't a true new land speed record is it?

I understood that test vehicle must be able to repeat the run shortly after the first so as to meet or exceed the standing record twice? It looks like they only did it once.

Also, a 15,000 foot inflatable helium tunnel? I want whoever thought that up to be shot immediately.

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Paris Hilton

Rocket science

Lt Col Angela Suplisson, commander of the 846th Test Squadron, said they "picked helium because it's not explosive," adding that hydrogen would be "probably a bad choice".

Well, not if the tunnel was reinforced: "y'all could git yezelf a aferburner goin' thaar."

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Rail Gun mounted on Rocket sled?

Now that would be cool, fire the railgun once the sled is up to mach 9 - whats that give you - a projectile going at mach 18.5 or thereabouts :)

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How to upgrade the Tube

"'Ello, luv, I'm just getting on the train. Right, be at the next station in a couple of minutes. Mach 7. No, dear, I'm not upset about something, they've filled the Tube with helium. People's voices always sound like this with helium gas. Mach 7, its a speed, dear, quite a bit above what the car goes at. No, dear, its nothing that can work for the car."

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oxo
Flame

They cheated

Mach number is a measure of speed related to the speed of sound.

As this test was conducted in Helium, the speed of sound is higher and thus Mach 1 = 972 m/s compared with 331 m/s for air (both at 0 deg C)

So, was the actual speed Mach 9 Helium (31432 km/h) or Mach 9 Air (10724 km/h)? Given that they think it was only "probably" not a good idea to run a rocket sled through a hydrogen tunnel I think we know the answer...

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Boffin

Mach 18.5...

Even if helium having a higer mach figure is taken into account, Mach 18.5 = 6,123.5m/s, which is 0.0000204% of the speed of light (299,792,458m/s).

Still no big smeg then, but it might be enough to get you to the pub for last orders, but then I guess relativity starts to come in to play so there's a possibility you might get there before you set of...

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How can they be so sure hydrogen is a bad choice?

I think they need to test it to be sure.

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Joke

It may be the fastest train ever...

But if it were running on Network Rail's tracks, it would still be delayed for some incomprehensable reason.

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picture of exploding tunnel

I have a memory of seeing a previous picture of this tunnel and a rocket sledge idea, and it going terribly wrong. Hydrogen in stead of Helium seems to ring a bell. ( to save cost ) .

But I can't find a link to it, come on some one, am I going mad or doea such a picture exist ?

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I wonder if they let Catburd watch this one.

"He's fast, I'll give Banzai that. But one heat-seeking missile

and he's history."

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Go

Not one for the record books.

Oxo, It might have popped out the far end of the tunnel into air as it finished accelerating. That would also allow measurements of performance in air, which was presumably the object of the test.

However, these things don't enter the record books without independent adjudication, I think.

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Hydrogen not neccessarily a bad idea.

Hydrogen's only a problem when there's oxygen around too. in a 100% hydrogen enrivonment, the gas wouldn't ignite. Not to mention hydrogen doesn't typically explode unless it's under a lot of pressure to start with.

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Happy

I sence some friction here...

actually they use helium to reduce the friction of air against the carriage. I think it dates back quite a while as i have seen this used before. I belief it was in simular tests. As to the reason they state, that, " its probably a bad idea to use hydrogen " has nothing to do with its density but with the simple fact that it would ignite.

Ps, The SR71 spy plane was famous for its friction at high speeds, normal procedure was to taxi it to the runway, and feul her up right before take off. The gaps between her plating were so big that feul would leak out. By the time it was airborn it normally would have lost about a quarter of its feul to leakage alone, hence the reason every SR71 flight starts with an airial feul stop.

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Paris Hilton

Errr

Not quite sure how much use this is... Sure it's big number (woooo), but I for one wouldn't be tricked by the

"Would you mind standing in the helium tunnel for a second" trick if they wanted to shoot me, nor would I appreciate having to wear breathing equipment for a trip on Eurostar!

Paris, well anything is quick compared to her!

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Sam

Out of idle curiosity

How many machs do you need to put something in space? Project HARP rings a bell.

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Black Helicopters

Let's think....

"But if it were running on Network Rail's tracks, it would still be delayed for some incomprehensable reason."

Wrong isotope of Helium......?

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Happy

We all want to know

Does breaking the sound barrier in a helium atmosphere cause a loud, high pitched, sonic squeek?

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Alert

@Michael

Sure, i'd love to see them set off a rocket without any oxygen.

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Where are the sheep -

- COME ON!!!!!!

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Escape Velocity

Mach 32 is escape velocity. If they managed to bump up the speed a bit, they could let it fly off the rails and into space.

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Rockets and Guns

OK, people, I probably don't need to explain this to everyone, but for the incredibly thick among you:

I think you'll find that regardless of actual need or the state of the budget, etc. the Navy, Air Force, and their ilk are likely to press for weapons development. Currently, the state of the art is a projectile launched from some sort of tube, which, when it strikes its target, explodes and causes all sorts of damage. The projectile can be launched from a so called "gun" which imparts all of its kinetic energy at once, or a "rocket" which trades chemical for kinetic energy as the projectile moves towards its target.

The "new generation" iterations of these ideas are the rail gun, and this mach 9 rocket sled. This was probably just a proof-of-concept test run, given the most favorable conditions possible. Would have been better had they tested this in space, but then what would the Russians or Chinese think? They'd be scared, or they'd race to develop weapons of this sort, also. So, ground testing it is.

I really does not matter what the warhead is, at these speeds. 100 lbs. (50 kilos) of cement traveling at mach 7-10 has so much kinetic energy that it tends to vaporize whatever it hits. Go ahead and classify the warhead. It's irrelevant. What these extremely high speeds tend to do is make it very difficult to intercept the projectile on its way to destroying the target.

The only thing that has a chance against both the "gun" and "rocket" version of these hypersonic projectiles is that South African kill bot that went crazy and decided to kill a few of its human operators.

Personally, I wouldn't want to put my own safety in the hands of a such a paranoid machine. It might decide *not* to intercept, just to spite the humans.

Oh, and a hydrogen-filled tunnel would burn when exposed to the exhaust gases coming out of the rocket motor, assuming, as most people do, that incomplete combustion occurred.

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Boffin

@ Silo Spen

The rockets would have their own oxidising agent (in the fuel, IIRC), so they would not require oxygen from the outside atmosphere to burn.

(Plus, they did launch this rocket in an atmosphere of Helium. So there would be little if any oxygen in that atmosphere.)

Do try and keep up. ;)

Posted anonymously for fear of a mach-9 rocket up the a$$...

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Happy

New amusement park ride?

I wonder if any amusement park "ride" designers are reading up about this?

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Silver badge

Land speed record...

While the sled was said to go Mach 7 (whatever the media), the official way to do land speed records is to take the average speed of TWO runs going opposite directions within a specified time (1 hour?). If the thing is going Mach 7, just say the thing goes only 10 mph on the way back, the average is pretty good. (Mach 3.5?), then again how is the average measured? Total time across the course runs (both ways) divided by the total distance (2 miles), it might not be too good then.

As for amusement park ride, it might not work, as the attention span of a typical bloke is shorter than the time traveled. I still wonder how the current ones stay in business. Then again I have strong doubts that anyone would survive the acceleration.

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IT Angle

@Chad H

"But if it were running on Network Rail's tracks, it would still be delayed for some incomprehensable reason."

No, just leaves on the track.

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Boffin

@Andrew Mulcock

I'm not sure if this tunnel is what you were thinking of, but you've got to admit the guy who invented it must be an evil genius, or have far too much time on his hands.

http://www.islandone.org/LEOBiblio/SPBI110.HTM

Jezza

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Boffin

@Shun F

Actually, the rocket sled is old news and not a weapon as such, but a test bed for weapons. Kind of high speed crash test carriage, where the test object is on the nose of the sled and they then drive it against armorplate, concreate or what ever they want to test it against.

I saw a film about this set-up few years back in public TV, when it was testing some secret thingy or another and it was then powered by multiple clusters of MLRS- rocket boosters (from standard rocket launchers) strapped on the back and acheived Mach 5 on that run inside of what looked like a horizontal building site garbage-chute.

They use these kinds of sleds as replacement to explosives, because explosions tend to distrupt the measurements, blowing up the high-speed cameras before they have all the data or forcing them to move the cameras too far from the test.

If I had to guess what they were testing at mach 9, I would bet my money on explosive formed penetrator's copper slug against chopham armor plate. Speeds match and there definately is a need for the testing.

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Joke

Mythbusters need not apply...

for a contract to supply crash test dummies

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Waste of energy

"Also, a 15,000 foot inflatable helium tunnel" - but tell the plebs not to leave their TV on standby, that 4 watts really will apocalyptic cause climate change.

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Gates Halo

So...

Must be a test for some high altitude venture, I'd reckon a guess at the sled was attached to a prototype scam jet fuselage.

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Stop

7:15 to Piccadilly breaks world snail record!

In a similar landmark event to the Amurrican shooper railgun, a North West commuter train recently moved faster than a snail (or slug) on it's way to Manchester Piccadilly station. A railway spokesman, known as the Fat Layabout, aka Mr Terry F*ckwit, was pleased to announce that following this remarkable achievement, the railway network would be moving onwards and upwards and might achieve reaching destinations on time at some point in the foreseeable future, possibly 2050.

I have deemed STOP as a suitable icon for this post, as that's what the trains do, a lot, usually several miles before their destinations.

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Coat

Late Christmas Prezzie?

"classified payload" designed by the Sandia National Lab for the US Navy.

I just want to know what Sandia National Lab has against the US Navy...

ok, that comment was coat-worthy...

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Hydrogen - why not?

The passage of the train at Mach 1+ would disrupt the polytunnel covering the track to a fare-thee-well, and the rocket exhaust would ignite the hydrogen when mixed with air.

But so what?

Maybe the polythene from the tunnel might partly melt and fall back and mess up the tracks for future use, but if they were clever and had a weakened section at the top it would all go sideways - but in any case, the hydrogen wouldn't "explode".

Hydrogen is a whole lot cheaper than helium, which is very expensive, plus it has about half the "air" resistance in the covered section of track.

Much more cost-effective. I'd have thought.

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I hope they tied it down

That "inflatable" track tunnel filled with Helium could be a worry if it wasn't tied down!

One way to loose your test-bed - watch it float away!

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Boffin

I remember

IIRC a TV program on this was aired here in the UK and it showed the sled accelerating along the track and the polytunnel kind of shattering/annihilating or something as it sped past.

At the end of the rail the tunnel opened to the air briefly and the payload went flying into a long & thick concrete block, the actual moment of impact was classified and thus the end of the video wasn't shown but presumably the test was for bunker busting warheads.

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Bronze badge

hydrogen is not explosive

any more than a piece of wood is explosive. It burns in the presence of oxygen, just like wood burns in the presence of oxygen.

It is difficult to even make explosive air/hydrogen mixtures, because hydrogen just tends to float away.

It is difficult to make an explosive air/wood dust mixture for the opposite reason, because the wood dust tends to settle out.

Nor is hydrogen very energy dense: a little bit of hydrogen gas takes a lot of space, that is, a given volume does not weigh very much because there is not much hydrogen in it.

Nor will it detonate at normal temperatures and pressures: the flame front is quite slow.

So hydrogen would be better for this application than almost anything else. Just not as good as hydrogen, which is almost as thin, and a noble gas as well.

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Anonymous Coward

Land Speed record rules are bs

those rules about having to average the speed of two runs is a bunch of crap made up by FIA

www.fia.com

rocket sleds have been around for decades and are definitely the holders of the true land speed record. Not that bs from fia.

mach 7 is mach 7, you'd have to be an idiot to claim that ThrustSSC is faster because it ran twice in one hour and averaged mach 1.07.

If you look in Guiness, Canadian sprinter Ben Johnson was the world's fastest man for many years AFTER he got busted. That's because, at 9.79s, he was faster than anyone else. He might not have been the world's fastest steroid free man but he was the world's fastest period.

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Happy

@Gordon

wouldn't float away not even one of those giant bannas float when filled with helium

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Anonymous Coward

Maybe, just maybe....

...they are starting to get a tad worried about spy satellites coming down outside the US.

If in doubt vaporise the sucker.

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