Scramjet Test Successful

An Anonymous Coward writes: "The Sacramento Bee is running this story about the first powered device to achieve "hypersonic" speeds in the Earth's atmosphere. In a series of DARPA-sponsored tests, at Arnold Air Force Base in Tennessee, a scramjet engine, encased in a titanium projectile, was fired from a 130-foot cannon, at an initial velocity of Mach 7.1. The scramjet's engines then ignited, and the object moved another 260 feet, in just 30 milliseconds, before it came to rest in a series of steel plates designed to halt the flight. Peak acceleration: about 10,000 G's. Elapsed time, including cigarettes & pillowtalk: less than a second. PS: According to this nifty page at NASA, Mach 7.1 is about 5406 MPH, whereas 260 ft, per 0.03 seconds, is about 5909 MPH."

Comments

I can see my first flight on one these babies now

[case_igl]

Ladies and gentlemen, welcome aboard LotsaCashSpentDevelopingThis Airways.

Flight Attendant #1:
"Once we reach our cruising altitude we will begin our complimentary beverage service. Coke products are free while beer, wine, and liquor may be purchased for..."

(interrupted by Flight Attendant #2):

"LotsaCashSpentDevelopingThis Airways welcomes you to Paris DeGaulle Airport. The local time is 12:14pm."

Read the article, plz.

[cprael]

According to this nifty page at NASA, Mach 7.1 is about 5406 MPH, whereas 260 ft, per 0.03
seconds, is about 5909 MPH.

Well, given that the projectile in question was accelerating at ~10K G for that 260 ft, from a starting velocity of Mach 7.1, one would expect the mean velocity over the 260 ft to be somewhat higher, eh?

Re:Read the article, plz.

[Stephen Samuel]

$ units '260ft/5406mph' seconds
* 0.032791847
/ 30.495385

Given that only 1 significant digit was given, .03 seconds is appropriate for mach 7.1. (remember your rounding rules). I presume that nasa's measurements were more accureate than 1/100th of a second, but they just didn't bother to print all those extra digits in the news release. Most news releases are edited by english majors, not physicists or mathematicians. They probably thought that .03 seconds was as accurate as mach 7.1 (fewer significant digits, but the same number of printed digits).

Calvins Beanie

[squaretorus]

This is great - forget those stupid little rotor blades! 10K G from a small metal tube on his head - lets see Hobbes bounce him NOW!!!

What to stick on that bad boy...

[Aqua OS X]

Honestly, all I can think of is "what could I tie to that thing?"

It's like I'm 8, I have a box of GI Joes that need to be punished, 1 scram jet engine, and a role of grey duct tape.

Re:What to stick on that bad boy...

[Gordonjcp]

Sod that, just use a pulsejet...

---

Lameness, lameness, first time I've hit the lameness filter. My first posting was everything above that line. Maybe it *is* lame, but sometimes I haven't got a lot to say...

Come on, Slashcode authors, SORT IT OUT!

For us barbarians

[m2]

260 ft is 79.25 m, 30 ms is 30 ms, so that's an average speed of 2.641 km/s or 9508 km/h. The initial velocity of 5325 mph is 2.380 km/s or 8570 km/h

Wow.

passenger problem

[jlemmerer]

if such high velocities are required to ignite the scarmjet, how will they do it in the future. firing it out of a cannon doesn't seem reasonable for me if you want to transport fragile goods such das humans. i heard rumors of bringing the scramjet equpped vehicle to high stratosphere with a carrier aircraft and then drop it to gain speed, but that also seems to be a rough ride.

Re:passenger problem

[rneches]

There are a few ways of getting around this problem.

• Drop the scramjet vehicle from a supersonic carrier vehicle.
• Build a giant rail gun, like in Gundam Wing.
• Attach JATO or RATO pods to the scramjet, and jetison them once hypersoninc speeds are reached.
• Use conventional means to reach a high altitude, and acheive hypersonic ingition using a balistic dive.
• Use an on-board oxidizer to fuel the scramjet like a rocket until atmosphearic ignition is possible.
• Build the scramjet to work first as a jet. Once at maximum jet speed, lock the jet blades and operate as a ramjet. Once at maximum ramjet speeds, jetison the jet rotors and combustion chamber to expose a scramjet surface.

There are a couple of other reasonable ways, but those are the ones that come to mind.

Re:OT:Metric please?

[brocktune]

As a guide to our international readers, here is a quick reference. Here in the US, meters are what the gasman reads. Gram is a kind of cracker. Kilos are what is hidden in tire wells at the border crossing in Tiajuana. Megatons are what we drop on people who speak in funny languages.

Auroura

[Perdo]

What makes this any different from a base bleed boat tail artillary shell? Again DARPA misses the mark. And if the Auroura is not a scramjet, what is it? This test is smoke and mirrors.

Re:Auroura

[Barbarian]

What makes this any different from a base bleed boat tail artillary shell? Again DARPA misses the mark. And if the Auroura is not a scramjet, what is it? This test is smoke and mirrors.

Well, this one carries fuel.

Re:Auroura

[dingbat_hp]

Well, this one carries fuel.

To some extent, so does a base-bleed shell.

Logistically, shells should be square-ended. You get more bang into the the chamber that way.

Aerodynamically, shells should be pointed at both ends, or in fact, even more pointed at the tail. The trouble with this is that it loses useful volume - although it's commonly done with small arms. The trick with base-bleed is that by burning a slow propellant in the tail of the shell, a high pressure gas plume is generated that makes the shell appear to be long-tailed, aerodynamically. You get the same compact shell layout (although you lose some space for propellant) and you get a long-range shell.

There are also rocket assist shells, but these are rare - they didn't work too well. They have some uses for heavy calibres with low muzzle velocities, but they lose in accuracy what they gained in range.

Re:I can see my first flight on one these babies n

[sopuli]

Of course at 10kG, by the time they arrive in Paris, all passengers will have changed into some kind of schnitzel.

Re:Pardon me if I'm wrong

[rneches]

Yes. The speed of sound increases with the density of the medium through which it propogates. For instance, the speed of sound through the crossection of average slashdot posters is aproximatly 8450 M/s.

intended use

[rneches]

The idea behind these sorts of technologies (scramjets and ramjets) is to fly very efficently, especially in the higher atmosphear. The technology to beat, in this case, is non-air breathing propultion (a.k.a. rockets). Because scramjets are air breathing, it is not neccesary to bring along an oxidizer, allowing for considerable weight savings.

Because of this, scramjets are critical for efficent, practical single-stage-to-orbit vehicles. The idea is that you operate in scramjet mode until the atmosphear thins out too much to sustain combustion, and then you start adding your own oxidizer. This will effectively turn the engine into a rocket motor. With scramjets, you could build a shuttle that would actually be fairly inexpensive to operate. Also, since the most expensive part of any mission is boosting into low earth orbit, any savings in the first stages of flight would dramatically bring down to costs for any mission, but especially heavy ones (like a manned mission to Mars).

The other reason to develop scramjets is for their raw efficenty. The use fuel at a fantastic rate, but at Mach 7, the fuel per unit distance is exceedingly good. Instead of supersonic (in this case hypersonic) flight being a luxury reserved for Concorde flyers, it would become the cheap, practical way of getting around. Of course, it would only make sense for the really long flights (like Chicago to Sidny), but the implications could be trans-global flights that cost less than regional flights.

Scramjets are very, very cool, and not just because they go fast.

Re:intended use

[Psiren]

In order for the scramjet to work though you have to be moving fast enough to collect enough oxygen from the air. So you'd need yet another system to start you off, be it rockets, jets or a being shot out of a big bloody gun ;-)

Re:intended use

[wowbagger]

The big problem with supersonic or better flight for commercial use isn't the fuel economy, it's the fact that many countries (the US being the first that leaps to my mind) don't allow commercial aircraft to fly supersonic over their land at any altitude. Therefor, you either have to land the scramjet at New York, and then fly subsonic aircraft to the rest of the US (assuming you are coming from Europe), or you have to cruse the scramjet subsonic (this is especially true if you are flying from, say, London to Saint Louis) over land.

Also, just because of the stresses involved, a supersonic aircraft will need to be much stronger than a subsonic craft like a 7[47]7. More strength == more cost and more weight (== still more cost).

Also, most scramjets are designed to burn hydrogen, not kerosene (like a commercial jet). Hydrogen requires cryogenic tanks, and has the nasty habit of migrating into the metal, finding any weakness, and setting up shop (a process called hydrogen embrittlement). While hydrogen has a much higher impulse than kerosene per unit weight, it is also more expensive.

Don't get me wrong - I'm looking at going from the US to the UK for a business trip soon, and I'd love to do it in less than eight hours. But I shan't postpone my trip until these things are flying....

Re:intended use

[gizmo_mathboy]

While the thought of having a hypersonic commercial vehicle is enticing, I think the intended use of scramjets are more for the military than anything. Remember this is a DARPA project. There isn't many DARPA projects that made it into the commercial realm. Well, I can think of at least one. ;-)

Heck, just a hypersonic projectile and/or missile would really change the landscape for Ballistic Missle Defense. Having a velocity several times faster than your target is a major advantage.

It wasn't mentioned in the article but the projectile used gaseous ethylene at 1000 psi, not hydgrogen, as its fuel. I love my Aviation Week subscription. :-)

As mentioned in another posting hydrogen embrittlement would be a concern in a larger vehicle, this is a 20% scale model. The biggest barrier is heating. Atmospheric heating is a big deal at Mach 7+.

A more detailed article can be found here at Aviation Weeks online site.

Re:intended use

[rneches]

The funny thing about the U.S. is that we already have the world's largest (publically financed!), most advanced and most expensive public transportation system in the world. The fact that everyone has to buy their own car to use it obscures that fact a bit, and makes it just anti-democratic enough for big buisiness to play along.

If only people would wake up and smell the smog, they'd realize that cities and states already fork over hundreds of billions of dollars a year to extend and maintain this public transportation system. Here in Boston alone, the Notorious B.I.G. D.I.G. has swallowed 60 billion dollars (check your paper for the latest figures), even as the T system languishes right on top of it.

Anyway, scramjets for comercial public transportation are a long way off. But when they get here, they would be nicely complimented by a decent mag-lev rail system. I'd guess both are roughly on the same time-frame for development and deployment.

hmm, let's see

[K.]

ballistic missile defence network + scramjet
cruise missiles = a lot of very pissed-off
nuclear powers.

The cannon is more interesting

[redelm]

I can see how this short test worked, and how they can get some scramjet performace data in the 30 ms of free flight. Ain't microelectronics wonderful?

But frankly, I'm more interested in that super cannon. Mach 7.1 is 7,500 ft/s (2,300 m/s) which is extremely high. It would have a max range (neglecting aerodrag) of 300 miles! Did they use a gas-gun?

Re:The cannon is more interesting

[KFury]

Sorry, there's a big difference between 'sending things into outer space' and 'achieving escape velocity.' The first simply means it could shoot something outside the atmosphere, or around 90 miles up. Having reached outer space, it can fall back down to Earth.

Reaching escape veolcity means that, ignoring aerodynamic drag while departing the atmosphere, the object has enough velocity to fully escape Earth's gravity well, so that it'll never come back. This is a couple orders of magnitude faster.

As for the replies to the post talking about sending things into orbit, that presents a different problem, because you couldn't stabilize an orbit without a burn at the apogee of the flight, to stabilize the flight path from a parabola, which would come back and slam into the earth, to a circular or elliptical orbit. So in addition to having to protect the electronics from the tremendous G-forces (or making it all out of a ferrous metal, so you can pile it through a railgun and not have to worry about it because every piece of the craft is being accellerated identically) you also have to put in enough fuel and an engine to make that stabilizing burn. Of course, ferrous fuel is hard to find...

stupid question?

[Marcus Brody]

From the article:


Scramjets, or supersonic combustion ramjets, burn hydrocarbon fuel but scoop oxygen out of the atmosphere to combust it....


...The Pentagon and National Aeronautics and Space Administration are both studying scramjet technology since it would allow missiles or spacecraft to travel longer distances and carry larger payloads than rockets.

I'm sure i'm missing something fundamental here, but where the hell are spacecrafts supposed to get the oxygen from?
I guess they must just mean using scramjet untill leaving the atmosphere, and then use onboard oxygen, but it is a little misleading

Re:stupid question?

[maggard]

Missiles and spacecraft are launched from down here at the bottom of the soup. If they can take advantage of the ambient gasses along the way (up, down, sideways) as an oxidizer then there's that much less material they have to lug along. Yes once in space a Scramjet isn't much use but to and from arbitrary "space" the majority of most trajectories are within enough atmosphere that Scramjets would be useful.

Imagine if your car/bus had to haul along it's own oxidizer in a honking big tank of super-cooled special-purpose gas next to the fuel tank, which is what all liquid-fuel rockets do today. Now imagine someone announced an engine that could possibly dispense with that heavy complex oxidizer tank that's been weighing down your car/bus and instead let the motor just suck in outside air - pretty exciting news eh?

Right now Scramjets are a tricky exotic tech requiring special materials and designs that push the envelopes for those fields. On the other hand the same was true for jet engines when they were developed yet all large and/or long distance aircraft use them pretty much exclusively today. This may be a technological blind alley or it may never be commercially viable but it's interesting stuff nonetheless, indeed exciting for the aerospace-heads.

Re:OT:Metric please?

[erlando]

In the rest of the world; feet are what we walk on, miles is some dude named davis and yards are what is on the back side of the houses..

Air breathing high speed vehicles

[mycr0ft]

OK, the point is that this is a scramjet engine, not that it is going fast. The idea folks, is that in future vehicles you can take off to high speed using a mag-sled or a more conventional aircraft and achieve high velocity and high altitude using earths atmosphere and at the last possible moment switch to a rocket engine using Liquid O2 (LOX) that you store aboard.
Part of the reason launch is so expensive (and dangerous) is that we have to carry LOX from the ground up along with the propellant.
--mycr0ft

MPH in a second.

[rjamestaylor]

Elapsed time, including cigarettes & pillowtalk: less than a second. PS: According to this nifty page at NASA, Mach 7.1 is about 5406 MPH, whereas 260 ft, per 0.03 seconds, is about 5909 MPH."

<humor>

Reminds me of the last time I was stopped for speeding. Officer said I was travelling 80 MPH in a 30 MPH zone. I answered, "But officer, that's impossible!" Puzzled, he asked me to explain. "I've only been driving for 5 minutes!"

</humor>

Sounds military to me...

[jack deadmeat]

And almost as cool as the LOSAT, which hits around 5000mph

Gas gun: yes. Plus: link to video

[risacher]

According to this page at the Arnold AFB site, yes, it used a two stage light gas gun.

They even have this video clip, but it doesn't look like much, I warn ya.

Coming soon to a backyard near you

[alumshubby]

I can hardly wait for Estes' toy version. Zero to solar escape velocity in three seconds flat!

Choice of words

[sammy baby]

The scramjet's engines then ignited, and the object moved another 260 feet, in just 30 milliseconds, before it came to rest in a series of steel plates designed to halt the flight.

Sure. Like the way my car "came to rest" in a telephone pole after I tried to drive it home after a fifth of Chivas Regal.

The market for these things

[dmatos]

As I see it is in less expensive surface-to-orbit vehicles. Use a standard RAMJET to acheive mach whatever-the-hell-you-need-to-start-the-SCRAMJET. SCRAMJET kicks in, and slingshots you out of the atmosphere, where conventional rockets can then manoeuver you. Hopefully, this could be made into a completely re-useable space shuttle.

Ideas quoted in this post are not mine, they come from a book called Silver Tower by an author I can't remember now. They used a magnetic launching track to get the shuttle up to the speed where the RAMJET would work, then the RAMJET until they could turn on the SCRAMJET.

Re:The market for these things

[Dyolf Knip]

There's been lots of discussion on /. about using scramjets as cheap earth to orbit vehicles. The big advantages they offer is that they don't need to carry their own oxidizers (for the in-atmosphere part of the flight, anyway) and if they're hooked up to a pair of wings you can fly it like a plane. The downside of course is that you can't use it from a standing start and another engine on board used solely to get it to scramjet speeds is just dead weight thereafter.

Re:I can see my first flight on one these babies n

[Ben Hutchings]

I would quibble with your 'time waiting for bags' - in my experience it rarely takes more than 15 minutes, though when flying to the US I often have to queue for a long time at immigration before collecting my bags (after which it takes 5 minutes to collect the bags).

You forgot to include taxiing time which is often 30 minutes or more of the gate-to-gate time.

Still, I'd be happy to cut my 10 hour trans-atlantic flights down to 1 hour.

Decimal system?

[Domini]

America ever hear of the decimal system?
SI units and whatnot...

Feet are things attached to legs (last I checked)

Can anyone convert the velocities to civilised modern measurements? Say meters? and kilometers per hour?

Next you will have them measuring speed in furlongs per forthnight!
-wink-

Re:Decimal system?

[Speare]

# units -v '5406mi/hr' 'km/hr'
5406mi/hr = 8700.1137 km/hr
5406mi/hr = (1 / 0.00011494103) km/hr

# units -v '5406mi/hr' 'furlong/fortnight'
5406mi/hr = 14531299 furlong/fortnight
5406mi/hr = (1 / 6.8816973e-08) furlong/fortnight

Re:Decimal system?

[Domini]

Admittedly that is a useful trait.

I think the only thing that SI finds in it's favour is that most of the measurements have some funky relation. As a novice physist I remember something between the relation of a meter and 1 second when it came to pendulum motion.

Alas my memory is clouded in my old age.
;)

Re:Decimal system?

[Domini]

not the same, sure, but based upon.

How many inches in a foot etc. (is not decimal-based.)

Hope this helps.

Forget Nukes, here's the arms race

[Uttles]

OK, so there are several countries out there that have the ability to destroy the world with a few nuclear bombs... well, that's just bad publicity these days, no government would want to wipe a country like Iraq off the map for good, what about all the innocent people that live there? Even though we have the "biggest guns" here in America, we continue to try and make newer, bigger, better ones, but now instead of blowing up an entire land mass we are making weapons that will be able to hit precise targets and travel at unimaginable speeds.

So here's the problem: just like every other new military technology, other countries will eventually get it. Hypothetically, let's say Russia makes a cannon that can fire an explosive projectile from Moscow to hit the World Trade Center in NY; they probably wouldn't do that (at least I hope not) but they would sell some of those to a bunch of small rogue countries out there who don't have "political correctness" or care about the welfare of a nation's innocent people. It all seems pretty scary to me. I mean missile defense sort of loses it's significance when the missile is travelling at mach 5.

What do we do? Well I guess we'd better make sure we have the biggest, best cannons and we have a whole bunch of them so all of those other countries will be too scared to use theirs.

Actually...

[Greyfox]

They used a very well designed potato gun, designed by the same guy who designed the Mach 1 potato gun reported on this site some years back.

Re:I can see my first flight on one these babies n

[TGK]

You're both wrong. Black hole or not, what happens when the jet is standing STILL. Hmmmm... that could be BAD.

Re:Am I the only dissenting opinion

[jayteedee]

"777 fly-by wire - 80's tech.....shuttle-60's tech"

Yes they are old technology and the use of older-mature technology is going to continue into the future. EVERYTHING on a rocket or commercial plane is certified, validated, and/or qualified. The rocket business industry wide still has a 50/50 chance of succesfully flying a new rocket design. And this is the current state with using tried and true ancient technology. Orbital Science Corp. is still using Ni-Cad batteries in ALL their launch vehicles to this day because the cost of qualifying lighter and more powerful Li-Ion and Ni-Hyd batteries for flight is not something they can sell to a customer. Tried and true is the only way to run these type of companies. Weight is like gold on a rocket, but qualified and tested hardware makes the gold-high-tech-gizmo look like sand.

The airplane business is UNWILLING to go back to the test pilot days of the 50's and 60's. The stigma of losing a test pilot's life is far to big a liability anymore. Even if we had remote pilots, the companies are just not willing to risk half a billion in investment to try something bleeding edge. Even if the problem was a fluke, the political/consumer fallout is far to great a risk to attempt. Nobody is these two business' take risk lightly, and that is NOT going to change anytime soon.

Any oxidizer injection done to a scramjet design can also be done to a ducted ramjet design for a whole lot less money.

Plasma magic is still vaporware (pun intended). It may or may not get fielded, but for certain the volumn production stuff and the workhorses for the industry for the next 10 years will be something else. You and me both might wish for the funding levels from the 50's and 60's, and for another Apollo program, but I'm not holding my breath.

This is your captain speaking...

[dstone]

Ladies and gentlemen, we'll soon be coming "to rest in a series of steel plates designed to halt the flight". We hope you enjoyed yourself and thank you for flying Scramjet Airlines.

Re:GPL It !

[Dyolf Knip]

The project cost $800,000 according to that Sacramento guy, just to be destroyed in split of a second

It's more than NASA accomplished and it used a lot less money. I hope the next test will last longer.

What I don't get was why they felt they needed to accelerate the thing to mach 7.1 before starting the scramjet. They'll work at any supersonic speeds, right?

Re:GPL It !

[Dyolf Knip]

Whoops, a little research shows the error in my ways.

A Ramjet works at mach 1 to 5 or 6, Scramjets take over from there. So the mach 7.1 is perfectly justified.

Re:Faster speeds...

[Tackhead]

> > That would mean be able to get anywhere in the world in less then [sic] 1/2 of an Hr.
>
> Your nuke will be delivered in 30 minutes or less, or it's free.

Fsck the nukes.

"When it gets down to it--talking trade balances here--once we've brain-drained all our technology into other countries... there's only four things we do better than anyone else: music, movies, microcode (software), high-speed pizza delivery."

- Neal Stephenson, Snow Crash

Re:Verbal Discord

[Tackhead]

> came to rest in peace (RIP)

..."came to rest" in one very flattened-out piece spread liberally through a series of steel plates?

"OK, we can handle 10000Gs acceleration. The million Gs on landing were a bitch!"

Re:30 milliseconds?

[Dyolf Knip]

this smells like an $800k proof-of-concept

Exactly. It hit the steel plates going 1000 ft/s faster than when it left the cannon. That's a lot of speed to add in a mere 0.03 seconds.

Too bad there aren't any accompanying pictures, but with a flight time of less than a second, I guess they'd be hard to get.

Nope. There are plenty of cameras that could take many pictures in such a period of time.

Re:Verbal Discord

[Dyolf Knip]

What was the last thing to go through the space hero's mind after he fell off the 10000 foot cliff?

His boots.

Re:fuzzy math

[Dyolf Knip]

Velocity leaving the cannon: 2380.4 m/s

Velocity as it gently plowed into the steel plates: 2641.6 m/s

delta v: 261.2 m/s

delta t: 0.03 s

v = a*t, therefore acceleration from the scramjet = 261.2/0.03 = 8706 g. Probably they just rounded up to 10k because it looked cooler.

10000 Gs?

[graveyhead]

Everyone seems so excited about the travel possibilities.

With an acceleration of 10000 G's, I will weigh 2,200,000 pounds during take-off. Exactly how is my body not going to be crushed to a thin paste before the 10-minute flight to London even gets started? That frog in that blender stood a better chance of survival than me in my trans-continental flight. Just a thought.

Re:fuzzy math

[dbrower]

if it delayed ignition after it exited the barrel, it slowed down. you really need to know the velocity at the time it lit, not as it left the end of the gun to know the acceleration. Assuming it slowed down any at all, 10k G is not out of line with the data reported.

-dB

Re:I can see my first flight on one these babies n

[PD]

Well, since the end of the war, Paris has had a schnitzel shortage. Always look on the bright side.

Re:I can see my first flight on one these babies n

[agallagh42]

Reminds me of a great quote by an american comedian (I don't remember his name) when asked by a canadian interviewer, "What do americans think of canada?"

Answer: "We don't"

Re:I can see my first flight on one these babies n

[JesseL]

Ah yes, the "balanced drive" from Charles Sheffiled's "McAndrews" stories. He didn't use a black hole though, IIRC it was a very massive disk compressed by electromagnetic fields. The stories can be purchased in ebook form from Baen here.

Re:Pulsejets, Scramjets, and PDE

[Gordonjcp]

Yep, PDE's certainly are very cool...

Pulsejets are crap compared to scramjets.

You're not comparing like with like. That's like saying piston engines are crap because they're not gas turbines.

You wouldn't stick a 450shp turboprop on a flexwing microlight, would you? Oh, you would... Well never mind then. :-)