USAF Scramjet Hits Mach 6, Sets Record

first post by Anonymous Coward · 2010-05-27 03:04 · Score: -1, Offtopic

first post!

Interesting... by TrisexualPuppy · 2010-05-27 03:04 · Score: 1, Interesting

How useful is this in the long run? What was the burn ratio compared to other scramjet vehicles of recent design?

Re:Interesting... by AdmiralXyz · 2010-05-27 03:08 · Score: 2, Interesting

How useful is this in the long run? What was the burn ratio compared to other scramjet vehicles of recent design?
Are there even any other scramjet vehicles in the operational testing phase? I was under the impression that the X-51, and the other vehicles in the Hyper-X program, are the only ones that've actually flown. Scramjets aren't exactly easy to test in the lab.

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Re:Interesting... by gatechman · 2010-05-27 03:13 · Score: 2, Funny

According to my sources scramjet technology has gone well past Mach 6. The govt. doesn't want you to know this.
Re:Interesting... by joggle · 2010-05-27 03:13 · Score: 4, Informative

According to the article there's three more vehicles which will be tested in the fall.
Re:Interesting... by Pojut · 2010-05-27 03:14 · Score: 5, Interesting

Scramjets aren't exactly easy to test in the lab.
Hell, even normal jet engines are tough to test. Have you seen the equipment used to keep those things stationary while testing them? Holy fuck .

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Re:Interesting... by Kozar_The_Malignant · 2010-05-27 03:15 · Score: 1

>Scramjets aren't exactly easy to test in the lab.
Once, maybe, but repeatability could be a problem.

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Re:Interesting... by Anonymous Coward · 2010-05-27 03:21 · Score: 1, Funny

If by "...doesn't want you to know this...." you mean "...highly publicized mach 10 test of the X-43 a few years ago..." then yes, you are correct. Otherwise, well, BS.
Re:Interesting... by WillDraven · 2010-05-27 03:29 · Score: 1

Also what altitude was this operating at? "Mach 6" doesn't mean much in terms of speed relative to the earth without an altitude.

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Re:Interesting... by beelsebob · 2010-05-27 03:30 · Score: 2, Informative

Yes, but not scramjet technology that uses ordinary jet fuel to power the engine. Said scramjets used hydrogen instead, and can't maintain flight for long because of how bulky the large hydrogen tanks are.
Re:Interesting... by phoenixwade · 2010-05-27 03:34 · Score: 1

I'm not trying to downplay the engineering involved with testing jet engines, but really, using the J58 as an example of a jet engine is like using an atom bomb as an example of an explosion.

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Re:Interesting... by tweak13 · 2010-05-27 03:42 · Score: 1

Why is that exactly? Sure, the J58 is a unique engine, but we've since made engines for airliners that put out three times as much thrust.
Re:Interesting... by Blitz22 · 2010-05-27 03:42 · Score: 1

That's just a sea-level test. If you want an altitude test..... http://facilities.grc.nasa.gov/psl/gallery.html/

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Re:Interesting... by Lumpy · 2010-05-27 03:43 · Score: 1

Actually Kerosene + Lox can do this. Problem is they are having problems with the exhaust temperatures are high enough to melt most aircraft components.

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Re:Interesting... by Pojut · 2010-05-27 03:45 · Score: 1

Chose that one because it was the first picture I came across that you could see good detail on the rig keeping it in place. But yeah, I agree, it is a bit overkill :-)

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Re:Interesting... by jgagnon · 2010-05-27 03:51 · Score: 1

Jet engine Viagra?

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Re:Interesting... by geckipede · 2010-05-27 03:51 · Score: 3, Informative

The differences are in how compact the engine is and exhaust velocity. Airliner engines are designed solely for efficiency and as such have bypass ratios that make start to look like a helicopter mounted sideways in a tube. The actual power generating bit of the engine is tiny and most of the thrust comes from shunting air through the outer parts at relatively low speeds without ever being compressed.

Generating exhaust simultaneously at high rate, high velocity and in a compact package is vastly different.
Re:Interesting... by icebrain · 2010-05-27 03:56 · Score: 1

Something like a GE90-115 might put out a heck of a lot more thrust at sea level than a J58 (and do it with less fuel to boot), but it isn't going to keep happily chugging along at Mach 3. There's more to comparing turbine engines than just looking at raw thrust at one specific condition.
It would be interesting, though, to see what a new engine meeting the J58 mission profile would look like. Of course, we'd have to spend a few years relearning/reinventing capabilities we pissed away^W^Wlost, but the end result would be pretty.

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Re:Interesting... by Anonymous Coward · 2010-05-27 04:04 · Score: 0

Also what altitude was this operating at? "Mach 6" doesn't mean much in terms of speed relative to the earth without an altitude.
Ouch. Earth's diameter is about 13Mm (this means roughly 13000km). Atmosphere--or a noticeable effect thereof--"ends" at about 0.1Mm. Even if scramjets were able to use the little oxygen left at an altitude of 100km, that wouldn't change much about speed relative to the surface.
It would take the spaceship, err, jet some time to ascend to an altitude of 100km, of course, but I digress ...
Re:Interesting... by stjobe · 2010-05-27 04:10 · Score: 2, Interesting

I agree that using the J58 as an example of a typical jet engine is rather like using an atom bomb as an example of an explosion.
At the same time, since the J58 is essentially a turbojet/ramjet hybrid, it might be said to be the distant forefather of the X51 engine.
Oh, and anything that makes me go look at pictures of the most beautiful aircraft in the world, the SR-71, is a good thing.

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Re:Interesting... by rhsanborn · 2010-05-27 04:14 · Score: 0, Redundant

They weren't measuring speed relative to the ground. They were measuring speed relative to itself. Regardless, the increase in distance is negligible. I went and did a quick look up for the X51 and it hit's altitudes of 70,000 feet, or ~13 miles.

Given a mean radius for the Earth of 4182 mi we get a circumference of 26,276 mi.
If we add the 13 mi of the test flight, we get a circumference of 26,358 mi.
With a grand total increase in distance of 82 mi over the entire surface of the Earth.

Let's even compare the height of the space shuttle on it's Hubble missions (the highest it goes) - 372 mi.
It's circumference is 28,614 mi.
It's a difference of 2,338 mi which is a lot, but with all of that altitude, is only an increase in 8% relative to the ground.
Re:Interesting... by imamac · 2010-05-27 04:18 · Score: 1

It's mach 10 you don't want to hit...you'll turn in to a newt.
Re:Interesting... by phoenixwade · 2010-05-27 04:23 · Score: 4, Informative

Others have expressed the detail, so I won't be redundant, but the J58 is on the extreme end of Jet technology even today, and that was the point of my analogy. Those airliner engines you mention produce more thrust and are more economical to operate and to maintain, by a very healthy margin. However, they are only good up to about 500 kts or so, as opposed to the 2000+ kts the J58 is capable of. Nor will they function at all about 60000 feet, whereas the j58 will at full or nearly full thrust. So, in comparison, modern airline engines of which you speak are not in the same class of tech, nor would you expect them to be, since their purposes are far different. On a side note; it's note related to the tech of the engines themselves, of course, but those airline engines also will never push as pretty an airframe through the air, wich disqualifies them on the asthetic front too.... {smile}

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Re:Interesting... by phoenixwade · 2010-05-27 04:24 · Score: 1

Pretty, though!

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Re:Interesting... by DeusExMach · 2010-05-27 04:28 · Score: 1

That's WARP 10, and the worst ST episode of any series EVER.
Re:Interesting... by jabelli · 2010-05-27 04:30 · Score: 2, Informative

If you're required to carry your own oxidizer, it's a rocket engine, not a jet engine.
Re:Interesting... by element-o.p. · 2010-05-27 04:38 · Score: 4, Informative

I think you misunderstand his point (or perhaps I am giving him too much credit for asking a really good question). Mach speeds are a ratio of the speed of the aircraft to the speed of sound. Mach 6 therefore means "six times the speed of sound". OK, nothing difficult there; most people here probably knew that already. Here's the rub: what is the speed of sound? Hint: it's not the same at sea level and at the 0.1Mm you mention, because the speed of sound varies with the density of the atmosphere. In other words, Mach 6 at sea level (~4500 mph) is not the same speed as Mach 6 at, say, 100,000 feet above sea level (~4100 mph).

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Re:Interesting... by ceiling9 · 2010-05-27 04:48 · Score: 1

It's not the Earth's circumference, but the change in air density. The speed of sound is highly dependent on air density, so the groundspeed corresponding to a given Mach number varies with altitude significantly.
Re:Interesting... by Anonymous Coward · 2010-05-27 04:51 · Score: 0

Useful??? They had to use a B-52 to get into the air. Then a rocket booster to go to 4.5Mach. Then this precious little stove pipe took it to 5.0 Mach.
If you built this thing into an SR-71 you would still not be going fast enough to light the SCRAM.
This is going nowhere, we should scrap this and go back to sail boats.
Re:Interesting... by BJ_Covert_Action · 2010-05-27 05:03 · Score: 1

So far as I understand, those three vehicles are the exact same model, but will simply undergo some slightly different tests. So, no, I don't think there are any other vehicles than the X-51 model being flown right now.

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Re:Interesting... by Animaether · 2010-05-27 05:14 · Score: 1

The rig keeping in place isn't even all that impressive, though. Really, as long as you can still hook up the fuel and electric lines, you could hold a jet engine in place with a reasonably sturdy cement casing.
You just won't get a heck of a lot of useful information out of it.
So on the end of simpler 'clamps', you've got something like..
http://www.aviationearth.com/jet_engine.jpg
While near the other end of the spectrum, you've got this bad boy..
http://www.rolls-royce.com/Images/08124008_tcm92-12791.jpg
Re:Interesting... by WillDraven · 2010-05-27 05:14 · Score: 1

You hit on my point precisely. Another poster missed the point but nonetheless provided an altitude of 70,000 ft. before doing a bunch of unnecessary math concerning the earth circumference.
Using this applet we can derive a speed of ~3962mph for Mach 6 at 70,000 ft. as opposed to ~4562mph at sea level. A 600mph difference is important enough to make the distinction in my opinion. :)

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Re:Interesting... by Gravitron+5000 · 2010-05-27 05:15 · Score: 2, Insightful

They weren't measuring speed relative to the ground. They were measuring speed relative to itself.
Umm, I think it was stationary relative to itself.
Re:Interesting... by WillDraven · 2010-05-27 05:17 · Score: 1

Oops, I just realized my altitude was at 400ft for my "sea level" number, it should be more like ~4569mph. Point still stands however.

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Re:Interesting... by BJ_Covert_Action · 2010-05-27 05:24 · Score: 1

To clarify, according to this source

The tests will be flown by four unmanned X-51 "Waverider" vehicles developed by a team including the U.S. Air Force, the Defense Advanced Research Projects Agency, NASA, Boeing Phantom Works and Pratt & Whitney.
So where I think the OP was asking if there are any other designs/previous models with which to compare this flight against, the three vehicles being tested in the fall would not qualify. The three vehicles being tested in the fall are the same vehicle, but just different serial numbers.

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Re:Interesting... by fahrbot-bot · 2010-05-27 05:49 · Score: 2, Interesting

How useful is this in the long run?

The usefulness, overlooked in the summary and (brief) article, but reported in The Register (longer article), is that this vehicle used jet fuel (JP-7) instead of Hydrogen. Additionally, it apparently flamed out at Mach 5, not 6.

The hypersonic X-51A ignited, burning a mixture of ethylene and JP-7 jet fuel, and once well alight switched over to all jet fuel operation.

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Re:Interesting... by element-o.p. · 2010-05-27 06:13 · Score: 1

Considering that 600 mph is roughly the typical cruise speed of a modern airliner, I would agree that it is a significant difference (even if it is only about 15% of the speed of the scramjet test vehicle).

On a somewhat related note, I thought it was interesting that the NASA applet gave a significantly lower speed for 70,000 ft. than my referenced source gave for 100,000 ft. (which should have been the lower speed). I suspect the NASA applet is probably more accurate than my source.

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Re:Interesting... by blair1q · 2010-05-27 06:23 · Score: 1

Ohhh, so close. Here, try this:
If you're required to carry your own reaction mass, it's a rocket engine, not a jet engine.
Re:Interesting... by WillDraven · 2010-05-27 06:35 · Score: 1

The temperature also has a significant effect on the speed of sound. It's my understanding that due to some interesting thermal properties of the earths atmosphere you can get some rather unintuitive changes in the speed of sound as you change altitude.

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Re:Interesting... by Rei · 2010-05-27 07:00 · Score: 2, Insightful

Useful??? They had to use a B-52 to get into the air. Then a rocket booster to go to 4.5Mach. Then this precious little stove pipe took it to 5.0 Mach.
Yeah! How can you call that useful? And speaking of wastes of time during our war with the Japs and the Nazis, did you hear what those crazy eggheads over at Los Alamos are doing? They're trying to build a "nuclear bomb" -- but all they've managed to do so far is irradiate a bunch of scientists. How is that useful?
(/snark)
This is a *test program*, not a final product. It's designed to gather data. This was the first flight of a hydrocarbon-burning scramjet, yet it's already managed an acceleration and climb rate faster than a typical commercial aircraft -- but in conditions of orders of magnitude greater drag. It would have gone faster and higher, but it had a flameout 200s in -- again, not that unusual in a first-of-the-kind test.
Scramjets are not designed to be standalone engines. They're meant to be a "mid stage" engine to orbital rockets or a final stage for high-speed intercontinental aircraft, operating in an . For orbital craft, the scramjet craft is either part of the first stage carrier rocket which launches payloads with a small kickstage, or itself has a small kickstage for final orbital maneuvers. Initial thrust for scramjet powered vehicles is to be provided by some combination of rockets, advanced jets, ramjets, or hybrids of the aforementioned techs. A particular hybrid of interest is the "dual mode" scramjet/ramjet combination, designed to operate from around Mach 1 or so up to 1/2 to 2/3rds of orbital velocity. To get up to Mach 1, cheap droppable rocket boosters are what will probably be used, at least early on. But what's really possible is at this point still a big subject of debate, and a lot more data is needed.

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Re:Interesting... by Iron+Condor · 2010-05-27 07:07 · Score: 1

Well - form an energy POV mach 6 at 60 kft is about 6% of what you need to get to Low-earth orbit.
According to my sources, the government has actually sent people INTO orbit.
But they've really tried to keep that secret.

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Re:Interesting... by Anonymous Coward · 2010-05-27 07:35 · Score: 0

the equation for speed of sound in a perfect gas is sqrt(ratio of specific heats of air x gas constant x air temperature).
Speed of sound varies with temperature - doesn't give a lick about density (for
Re:Interesting... by Impy+the+Impiuos+Imp · 2010-05-27 07:48 · Score: 1

So all the scramjet stuff I've been reading over the years is just theory? These are the first real, working ones?
Geeze, I thought this was 1960s tech.

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Re:Interesting... by Anonymous Coward · 2010-05-27 07:48 · Score: 0

Actually, the speed of sound doesn't vary with density of atmosphere--it varies with temperature.
Re:Interesting... by Sperbels · 2010-05-27 13:47 · Score: 1

So, if I throw a baseball, does that make me a rocket?
Re:Interesting... by Dragoniz3r · 2010-05-27 14:10 · Score: 1

A little further toward the "other end" of the spectrum:
http://science.ksc.nasa.gov/mirrors/images/images/pao/AS4/10074807.jpg
For a few seconds, anyways :D
Re:Interesting... by Ungrounded+Lightning · 2010-05-28 09:18 · Score: 1

Note, however, that temperature in the atmosphere varies with altitude (even without crossing weather system boundaries). This is due to both compression heating/cooling as the molecules move vertically and latent heat of condensation if the air has nontrivial moisture content.
Look up "lapse rate". Wikipedia has a nice article on it.

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Uh hu by Anonymous Coward · 2010-05-27 03:04 · Score: -1, Troll

Commercial transportation at Mach 6. That's definitely the application they're striving for. Definitely. Don't you have enough deadly toys by now?

Re:Uh hu by ShadowRangerRIT · 2010-05-27 03:11 · Score: 5, Insightful

Commercial applications do usually follow. Whether or not you agree with it, military research has led to an enormous number of scientific advances that were initially used by the military but later disseminated more broadly. Jet engines, the Internet, cryptography, GPS, nuclear reactors, etc. Mach 6 might be inefficient overkill for Earth-side transportation, but it may provide a viable means of launching spaceflights one day.

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Re:Uh hu by Pojut · 2010-05-27 03:16 · Score: 1

Whether or not you agree with it, military research has led to an enormous number of scientific advances that were initially used by the military but later disseminated more broadly. Jet engines, the Internet, cryptography, GPS, nuclear reactors, etc
My Google-Fu seems to be failing at the moment, but wasn't the internet originally conceived to keep track of nuclear weapons?

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Re:Uh hu by Anonymous Coward · 2010-05-27 03:19 · Score: 5, Funny

Fine. Except for jet engines, the Internet, cryptography, GPS, and nuclear reactors what has the military done for us?
Re:Uh hu by Pojut · 2010-05-27 03:20 · Score: 4, Funny

Little plastic Army Men

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Re:Uh hu by Anonymous Coward · 2010-05-27 03:46 · Score: 0

From what I understand, it was originally designed to provide a redundant means of communication in the event that an area was destroyed. It needed to be able to route around problems.
Re:Uh hu by cthulu_mt · 2010-05-27 03:47 · Score: 1

http://en.wikipedia.org/wiki/DARPANET

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Re:Uh hu by Pojut · 2010-05-27 03:50 · Score: 1

THAT'S what I was looking for. Thank you:-)

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Re:Uh hu by Anonymous Coward · 2010-05-27 03:52 · Score: 0

I can live with military research, if they're honest about it. I am allergic to bullshit though. Even if scramjets will some far away day be used for hypersonic commercial transportation, which I don't think they will, then that is still not a factor in their development. Pretending that this is anything but weapons technology research is deeply dishonest.
Re:Uh hu by notommy · 2010-05-27 03:59 · Score: 1

Commercial transportation at Mach 6. That's definitely the application they're striving for. Definitely. Don't you have enough deadly toys by now?
Blagh! Not another one. Go back to wheatgrass and let the men decide when we have enough deadly toys.
I think most men would agree that the answer to that is "not quite yet."
Re:Uh hu by jeffmeden · 2010-05-27 04:03 · Score: 3, Informative

Are you trying to point out that the internet wasn't a military innovation by stating its purpose was to track nuclear weapons (*military* nuclear weapons)?
And for what it's worth, the original purpose was to allow communication between points with no single path of failure (insert beneficial military application here like giving combat orders in the event of a nuclear strike); it started in universities, national labs, and large military bases who had the budget to pull the wires, and before we knew it there were all kinds of fun uses for it like MUD games and e-mail and slashdot and finally facebook; the ultimate military weapon.
Re:Uh hu by Dishevel · 2010-05-27 04:06 · Score: 4, Informative

Radial Engines, Kevlar, Ceramic Technologies, Radar, Microwaves, Food Preservation, Someone else keep this going.

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Re:Uh hu by Anonymous Coward · 2010-05-27 04:10 · Score: 0

Nope. The original idea was a method for the quick dissemination of information.
http://en.wikipedia.org/wiki/ARPANET
Re:Uh hu by newcastlejon · 2010-05-27 04:13 · Score: 2, Informative

Rocketry. 'Nuff said.

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If God forks the Universe every time you roll a die, he'd better have a damned good memory.
Re:Uh hu by OzRoy · 2010-05-27 04:14 · Score: 3, Funny

Brought peace!
Re:Uh hu by SnarfQuest · 2010-05-27 04:28 · Score: 1

khaki pants, steel toed boots, marching bands, don't ask don't tell, jeeps and humvees, and those guys who forcibly sent that kid back to Cuba.

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Re:Uh hu by Anonymous Coward · 2010-05-27 04:35 · Score: 0

If God forks the Universe every time you roll a die, he'd better have a damned good memory.
Copy on write, baby.
Re:Uh hu by Magada · 2010-05-27 04:37 · Score: 1

Self-heating MREs.

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Re:Uh hu by element-o.p. · 2010-05-27 04:39 · Score: 3, Funny

Well, for one, neither German, Japanese, nor Russian is my native language...

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Re:Uh hu by Idiomatick · 2010-05-27 04:48 · Score: 0, Troll

The last air-speed record NOT set by the military was in 1935 at 566km/h. The fastest commercial aircraft today is 2,500km/h. I imagine that some of the tech was from the military.

While I'd love a world where science and science funding was not mostly military table scraps the options we have at the moment seem to be military scraps or a complete lack of scientific funding and development.
Re:Uh hu by Idiomatick · 2010-05-27 04:53 · Score: 1

Err... not so much keep track of. You know the /. saying 'the internet treats censorship as damage and routes around it'... Originally the damage that the internet was designed to 'route around' would have been damage caused by war/nuclear war. That way communications could remain open even with a large amount of damage. It is that flexibility that has kept the internet up and running since it passed infancy without ever shutting off.
Re:Uh hu by GodfatherofSoul · 2010-05-27 04:59 · Score: 1

Doesn't this follow NASA's research though?

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Re:Uh hu by Machtyn · 2010-05-27 05:16 · Score: 1

Toilet paper.
Re:Uh hu by guanxi · 2010-05-27 05:17 · Score: 1

military research has led to an enormous number of scientific advances ...
There are definitely benefits, but that's an expensive way to obtain them. If we invest directly in the science and skipped the weapons, it would much cost less. Also, we could choose to invest in scientific advances -- or other things -- that are more beneficial to society than those the military produces accidentally. (For those inclined to economics, I'm talking about opportunity cost.)
I'm not arguing against military spending -- it's absolutely necessary. And I agree that the scientific advances offset the costs to degree, they just don't justify the costs by themselves (our security justifies the costs).
Re:Uh hu by jimbolauski · 2010-05-27 05:20 · Score: 2, Funny

and those guys who forcibly sent that kid back to Cuba.
Janet Reno?

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Re:Uh hu by Anonymous Coward · 2010-05-27 06:05 · Score: 0

brought jobs and pork bellies
Re:Uh hu by blair1q · 2010-05-27 06:25 · Score: 1

Jets don't work in space.
You need a rocket to get up to scramjet speeds, then maybe you can use a scramjet as a second stage, but once you're in thin enough air, you need a rocket again.
Re:Uh hu by dpilot · 2010-05-27 06:28 · Score: 1

To continue, way back then, there were lots of commercial attempts at online services, like CompuServe, AOL, GEnie, Prodigy, TheSource, etc, etc, etc. They all had one common feature - they were OWNED from the start, and their owners wanted the whole pie.
The internet WON because it wasn't owned, it wasn't limited to one owner's profit-oriented vision.
Fast-forward and you'll see that the same types of commercial interests that failed to produce an internet now are trying to get back to the same point - owning the whole thing, and limiting it to their own profit-oriented vision. In addition, they've taken the original robust routing concepts, gutted it, and turned it into a whole bunch of failure locations called "peering points" that of late seem to fail for business, not technical reasons.

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Re:Uh hu by Anonymous Coward · 2010-05-27 06:31 · Score: 0

Radial Engines, Kevlar, Ceramic Technologies, Radar, Microwaves, Food Preservation, Someone else keep this going.
For varying definitions of "Food", I guess. =( @ MREs
Re:Uh hu by Anonymous Coward · 2010-05-27 06:53 · Score: 0

Super glue* and duct tape**.
Wait ... does that mean that the military is responsible for holding the world together? That's just so wrong, man!
* Invented by 3M, first used to moisture-proof ammunition cases in WW2.
** Invented while researching materials for gun sights in WW2. Urban legend states that it was first used to seal battle wounds.
Re:Uh hu by c++0xFF · 2010-05-27 07:02 · Score: 1

Super glue* and duct tape**.
Wait ... does that mean that the military is responsible for holding the world together? That's just so wrong, man!
* Invented by 3M, first used to moisture-proof ammunition cases in WW2.
** Invented while researching materials for gun sights in WW2. Urban legend states that it was first used to seal battle wounds.
(Accidentally posted AC ... whoops)
Re:Uh hu by mcgrew · 2010-05-27 07:25 · Score: 1

I hope you're joking. The history of toilet paper

Joseph Gayetty is widely credited with being the inventor of modern commercially available toilet paper in the United States. Gayetty's paper, first introduced in 1857, was available as late as the 1920s. Gayetty's Medicated Paper was sold in packages of flat sheets, watermarked with the inventor's name. Original advertisements for the product used the tagline "The greatest necessity of the age! Gayetty's medicated paper for the water-closet."
Seth Wheeler of Albany, New York, obtained the earliest United States patents for toilet paper and dispensers, the types of which eventually were in common usage in that country, in 1883.[4]

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Re:Uh hu by Lesrahpem · 2010-05-27 08:43 · Score: 1

What about freedom and liberation???
Re:Uh hu by radtea · 2010-05-27 08:53 · Score: 0, Troll

Whether or not you agree with it, military research has led to an enormous number of scientific advances that were initially used by the military but later disseminated more broadly.
So did the space programme, with the notable advantage that it killed orders of magnitude fewer people.
So while military research is one particularly wasteful and stupid way to get these results, there is really no justification for promoting over the many other ways that are far less wasteful and stupid.

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Re:Uh hu by radtea · 2010-05-27 08:54 · Score: 0, Troll

Killed millions and millions of people?

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Blasphemy is a human right. Blasphemophobia kills.
Re:Uh hu by radtea · 2010-05-27 08:56 · Score: 1

Dresden, London, Stalingrad, Pearl Harbour, Hiroshima, Carthage, Ypres, Crimea, Nanking, the Crusades... Really, it's the gift that keeps on giving!

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Blasphemy is a human right. Blasphemophobia kills.
Re:Uh hu by eples · 2010-05-27 09:11 · Score: 1

CDMA cell phone technology => CDMA

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I'm a 2000 man.
Re:Uh hu by o2binbuzios · 2010-05-27 09:22 · Score: 1

Trauma care, radar, night vision, Jeeps, submarines, swiss army knives and roads. Oh Yeah - Flying Death Lasers http://www.popsci.com/node/19965
Re:Uh hu by Anonymous Coward · 2010-05-27 10:59 · Score: 0

All these posts listing technologies and not one mention of transparent aluminum? Who gave you all geek cards?
Re:Uh hu by Idiomatick · 2010-05-27 20:33 · Score: 1

How was this a troll? It was a couple facts... Hughes H-1 Racer was the last non-military air speed record set in 1935 (apparently though if you count seaplanes there was one in 1934 that did 709km/h... dunno why it was so much faster). And the Tupolev Tu-144 was like a faster concorde the russians made which hit 2,500km/h.

I mean the national science foundation gets more than DARPA but the NSF is the whole science branch of government (obviously other bits get research too like DoE).... and DARPA is a project that the DoD happens to have; mostly used to help determine what the military should spend its tons of research money on. Military pushing research isn't remotely new either. http://en.wikipedia.org/wiki/Military_funding_of_science
Re:Uh hu by Anonymous Coward · 2010-05-27 22:31 · Score: 1, Funny

Or British English for that matter....
Re:Uh hu by element-o.p. · 2010-05-28 10:50 · Score: 1

Well said, guv'nor!

--
MCSE? No, sir...I don't do Windows. Yes, I am an idealist. What's your point?

Why so short bursts? by Henriok · 2010-05-27 03:05 · Score: 3, Interesting

Why are these engines burning for such short times? Are these engines so early in development that they really can't get them to be stable and safe for more than 12 seconds? Sounds a lot like fusion: it works but it's not yet useful.

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- Henrik

- when the Shadows descend -

Re:Why so short bursts? by grasshoppa · 2010-05-27 03:08 · Score: 5, Insightful

Proof of concept. Scientists can only go so far on theory ( and it's impressive how far they do go ). At some point their research hits a point where they need to perform experiments.

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Mod me down with all of your hatred and your journey towards the dark side will be complete!
Re:Why so short bursts? by MozeeToby · 2010-05-27 03:09 · Score: 5, Insightful

Keep in mind that at mach six 200 seconds is 400 kilometers. That's already enough range to make a useful weapon (and yes I realize there was some acceleration time in there). Heck, that's already longer range than the most advanced missiles that many countries have. Increase the stability to just 10 minutes of burn time and you've got a missile that can go 5% of the way around the world.
Re:Why so short bursts? by MouseR · 2010-05-27 03:11 · Score: 1

Mach 6. 200 seconds. Makes a long walk home.
Re:Why so short bursts? by shadow349 · 2010-05-27 03:13 · Score: 4, Interesting

Are these engines so early in development that they really can't get them to be stable and safe for more than 12 seconds?
Are you talking about the scramjet or the events at Kitty Hawk in 1903?
Because Wilbur already had the first chance, Orville took his turn at the controls. His first flight lasted 12 seconds for a total distance of 120 feet (36.5 m) - shorter than the wingspan of a Boeing 707.
Re:Why so short bursts? by rufty_tufty · 2010-05-27 03:21 · Score: 3, Insightful

Likewise you want to stop the test before failure so you can look for signs of component wear and material stress so that you know what to improve for next time. Stopping at 200 seconds and finding this out is very useful. Stopping at 201 seconds after it has exploded and you have to work out from the pieces what went wrong is not as informative.

--
"The weirdest thing about a mind, is that every answer that you find, is the basis of a brand new cliche" -
Re:Why so short bursts? by ckaminski · 2010-05-27 03:24 · Score: 5, Insightful

Except they're not recovering these vehicles for analysis.
Re:Why so short bursts? by Pharmboy · 2010-05-27 03:24 · Score: 4, Informative

Not only that, but you can't always be sure which part is the weak link, what will break. A few tests at hypersonic is guaranteed to make an engineer say "ok, that's an issue we weren't aware of", and confirm much of what they already knew. They may have to make some part that they *thought* would be ok out of a different, stronger alloy, etc. Of course, at this speed, every tiny error in engineering is amplified, as at Mach 6, you cross a lot of real estate in just a few seconds, so the word "precision" doesn't adequately describe the level of perfection required in the test system build.
Being a pioneer at anything guarantees surprises, and best of all, learning new things.

--
Tequila: It's not just for breakfast anymore!
Re:Why so short bursts? by mprinkey · 2010-05-27 03:24 · Score: 1

It is a question of stages. The timescale that need to be designed for initially are based on the engine size divided by gas flow speed. That is maybe 10s of microseconds. The next timescale may have to do with longer scale oscillations in the engine structure...that is probably on the order of 1 - 100 milliseconds (10-1000 Hz). After that, you need to start worrying about heat...things melting, expanding, coating eroding...those are probably 1-100 seconds.
The smallest timescales are the hardest to fix, because they are harder to identify and control. When it comes to cooling, etc...these are easy to fix by comparison. At least in terms of making the thing function. I can't think of anything that would have a timescale on the order of seconds...unless it is a pump failure or other supporting device. I'd bet that if it would run for 200 seconds, it would probably run for much longer. It leads me to believe that they have most of the kinks worked out and can start work on developing products instead of the technology.
Re:Why so short bursts? by WED+Fan · 2010-05-27 03:27 · Score: 1

About 360 km if i did the math correctly.

--
Politics is the art of looking for trouble, finding it everywhere, diagnosing it incorrectly and applying the wrong fix.
Re:Why so short bursts? by stupid_is · 2010-05-27 03:28 · Score: 1

I wonder how many pieces it was in after it was terminated

"Something then occurred that caused the vehicle to lose acceleration. At that point, the X-51A was terminated as planned."

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-- Intelligence is soluble in alcohol
Re:Why so short bursts? by icebrain · 2010-05-27 03:30 · Score: 2, Interesting

A couple reasons:
Testing scramjets on the ground is really, really hard, and you can only do it for a very short time (much less than a second).
Testing scramjets in flight is really, really expensive. And when your funds are limited, you can only build subscale air-dropped missile-sized vehicles instead of full-sized, self-launching, reusable ones (in part because of the "cheaper now and more expensive long-term" being prefereable to "more expensive now and cheaper in the long run" thinking that brought us the Space Shuttle).
Making things even more difficult is that we pissed away a huge amount of research (from both the US and UK) on scramjets and high-speed flight a couple decades ago. Companies like Marquardt basically specialized in ramjet-style engines, and were hard at work developing scramjets and other neat high-speed propulsion 40+ years ago. They were very close to having flying hardware. But now, all of the hardware, most of the documentation, pretty much all of the institutional/unwritten knowledge, and most of the personnel are gone. We're having to reinvent the high-speed flight wheel almost from scratch, just like we're doing with heavy-lift launch vehicles, manned lunar flight, and ballistic missile defense, all of which we had operational in the 70s.
It's disgraceful, really, how we piss away useful technology and other exceptional things. There must be some kind of relationship to crabs in the human psyche that's responsible for this self-loathing anti-achievement personality trait.

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The meek may inherit the earth, but the strong shall take the stars.
Re:Why so short bursts? by DerekLyons · 2010-05-27 03:33 · Score: 3, Informative

Likewise you want to stop the test before failure so you can look for signs of component wear and material stress so that you know what to improve for next time. Stopping at 200 seconds and finding this out is very useful. Stopping at 201 seconds after it has exploded and you have to work out from the pieces what went wrong is not as informative.
Since the vehicle was deliberately crashed into the ocean and not recovered - there's nothing to examine for wear and stress, whole or in pieces.
Re:Why so short bursts? by WED+Fan · 2010-05-27 03:35 · Score: 1

Did a quick skim of the article for altitude and couldn't come up with an adjustment so I stuck with near sea level numbers.

--
Politics is the art of looking for trouble, finding it everywhere, diagnosing it incorrectly and applying the wrong fix.
Re:Why so short bursts? by whitehatnetizen · 2010-05-27 03:38 · Score: 1

150 years ago your post may have gone something like: "Why are these heavier-than-air 'Air planes' flying for such short times? Are these propellers so early in development that they really can't get them to be stable and safe for more than 12 seconds? Sounds a lot like the automobile: it works but it's not yet useful."
Re:Why so short bursts? by hargrand · 2010-05-27 03:38 · Score: 1

Why are these engines burning for such short times
Two reasons come to mind:
1) At 4,000lbs, they don't hold enough fuel to run the engine for more than 200 seconds.
2) The various loads overwhelm the airctaft structure which subsequently disintegrates.
Not sure which one, but I'd put my money on 1.
Re:Why so short bursts? by hargrand · 2010-05-27 03:39 · Score: 2, Insightful

Except they're not recovering these vehicles for analysis.
That's what datalinks are for.
Re:Why so short bursts? by Yvanhoe · 2010-05-27 03:43 · Score: 1

Sounds a lot like fusion: it works but it's not yet useful.
Mach 6 during 12 seconds is 23 kms. During 200 seconds it is 790 km. Useless for a plane, but imagine what a drone or a missile could do. Short range but no possibility of missile interception : it is already useful despite being a prototype.
I am however disappointed : I thought it was supposed to achieve Mach 10 ?

--
The Wise adapts himself to the world. The Fool adapts the world to himself. Therefore, all progress depends on the Fool.
Re:Why so short bursts? by mrops · 2010-05-27 03:53 · Score: 1

Not sure how fast it reached Mach 6, however, at Mach 6 in 200 seconds, you have covered over 250 miles (400 km). That's a lot of ground. No point continuing the experiment if whatever you are monitoring can't be monitored because its so far out.
Re:Why so short bursts? by zonker · 2010-05-27 04:03 · Score: 0

The Reg (yeah I know) says it got up to 70,000 feet at approx Mach 5. I'm seeing different numbers depending on the article so YMMV.

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Large print giveth, and the small print taketh away
Re:Why so short bursts? by LordLimecat · 2010-05-27 04:06 · Score: 1

According to this article, ICBMs already travel at close to Mach 20 during the boost phase and Mach 10 on impact. Missiles have no problem going faster than jets, why do you think they are so effective?
Re:Why so short bursts? by Captain+Hook · 2010-05-27 04:12 · Score: 1

Mach 10 is the goal of engines burning Hydrogen as a fuel. This aircraft is using almost standard jet fuel which is a lot more compact and easier to handle.

--
These comments are my personal opinions and do not necessarily reflect the opinions of the other voices in my head.
Re:Why so short bursts? by rhsanborn · 2010-05-27 04:20 · Score: 1

I looked up a previous (Mach 5) run of the X-51 and saw 70,000 ft, and used that for back of the napkin calculations in another response. The difference in ground speed is pretty much negligible.
Re:Why so short bursts? by kaiser423 · 2010-05-27 04:22 · Score: 1

This one went 200 seconds. At Mach 4.5 you're covering large areas and are starting to outrun all of your assets that are tracking it and gathering data. So, you either run for 200 seconds at a cost of $X for all the assets, or run for 400 seconds and cost $X*1.75. Is that extra little bit of running time worth the extra cost? Apparently not at this stage, otherwise they would have let it wander off range and had more assets further off the coast.
Re:Why so short bursts? by Anonymous Coward · 2010-05-27 04:22 · Score: 0

Mach 6 = 2041.74m/s so 2041.74*200=408348m or about 400km
Re:Why so short bursts? by Anonymous Coward · 2010-05-27 04:27 · Score: 0

His first flight lasted 12 seconds
That's longer than most /.'ers sexual encounters ;)
Re:Why so short bursts? by toxonix · 2010-05-27 04:28 · Score: 1

mach 6 = 2041.74 m/s so in 12 seconds (assuming it hit mach 6 right away):
2041.74(m) * 12(s) = 24492 meters or ~15 miles
I'm not sure what my point is. But thats
76.0931 miles per minute
4565.59 miles per hour
I imagine 12 seconds worth of unicorn farts is pretty expensive.
Re:Why so short bursts? by CyprusBlue113 · 2010-05-27 04:32 · Score: 2, Insightful

ICBMs do not do any jetting at all, its not a comparison, as they are ballistic rockets. You can think of them as flying mortars more than missiles. The closest applicable missile would be a cruise missile, but honestly, they are designed more for distance than speed. You don't need your cruise missile to get there ridiculously fast, but you do want a ridiculous range for them, at a sufficient speed to not be destroyed or give advanced warning, while still making it to the target in time for intercept.

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a handful of selfish greedy people are no match for millions of selfish, greedy people -u4ya
Re:Why so short bursts? by element-o.p. · 2010-05-27 04:46 · Score: 1

Useless for a plane...
Not necessarily. My airplane only has a range of approximately 280 km (but it takes a lot longer than 200 seconds to cover that distance). It may not be the *most* useful airplane at the airport, but it is 1) fun and 2) great for building flight time, since it is so freaking slow :)

--
MCSE? No, sir...I don't do Windows. Yes, I am an idealist. What's your point?
Re:Why so short bursts? by Anonymous Coward · 2010-05-27 04:51 · Score: 0, Flamebait

Yes, and the next flights rapidly increased in duration.
The Wright brothers already had something in 1903 that scramjets never had so far, passengers.
From Wiki: "While very short suborbital scramjet test flights have been performed, no flown scramjet has ever been designed to survive a flight test."
Scramjets don't even survive their flights. I think the Wrioght brothers win here again.
We've been dicking at scramjets for decades. It's a go-nowhere technology designed to generate degrees (as in PhDs, not temperature), mostly for weapons reasearch. Weapons against who, I don't know.
This will never be a practical, money-making technology. It's almost as bad as fusion power.
Re:Why so short bursts? by magarity · 2010-05-27 05:05 · Score: 1

Keep in mind that at mach six 200 seconds is 400 kilometers. That's already enough range to make a useful weapon

Yeah that's a great weapons platform range except to launch it they used a B52 with a 9,000+ nm range. Speed is the thing here, not range. But I don't get it because being stealthy at slower speeds is easier than super high speed for military aircraft wishing to escape countermeasures.
Re:Why so short bursts? by MozeeToby · 2010-05-27 05:40 · Score: 5, Insightful

It's all part of the Prompt Global Strike program. Eventually the goal is to have scramjet powered missiles with a range of 12000+ miles. Allowing you to fire an obviously non-nuclear missile from Kansas to North Korea and have it hit the target in less than 3 hours. Basically, even launching a B2 for a direct strike takes days or weeks. Refueling planes need to be put into the air, mission plans drawn up, clearance over foreign airspace cleared, pilots briefed, etc. They want to be able to say "Fire" and have the missile in the air within minutes and at target within hours; with the added benefit of not putting any American lives in harms way.
Re:Why so short bursts? by LittleBigScript · 2010-05-27 05:42 · Score: 1

Good thing Orville wasn't on the No Fly List.
Re:Why so short bursts? by bkaul01 · 2010-05-27 06:25 · Score: 3, Interesting

Scramjets have no moving parts; it's a duct and a fuel injector. That's it. Wear is a non-issue here.
Figuring out what shape that duct needs to be in order to get stable combustion, however, is far from a trivial problem; it's not just the fluid dynamics of the supersonic flow that must be considered ... thermodynamic losses can be large enough to quench the flame, and where in the duct those losses occur is as important as their magnitude. With most sorts of engines, second-law analysis is only something you look at to refine the efficiency of the technology once it's mature and functional. With scramjets, it's critical to making them work at all. Building one of these, with all our modern computer modeling technology, is kind of akin to building the first rockets with no computers at all.
Re:Why so short bursts? by Anonymous Coward · 2010-05-27 06:31 · Score: 0

Not sure, but I suspect that the problem is atmospheric heating. Atmospheric heating tends to be worst on the leading edged, and the aerodynamics of lifting bodies is such that they usually need extra weight in the nose to be trimmed correctly. So earlier experimental bodies used a giant copper heat sink for a nose rather than an active cooling system or high-temperature/low heat content/low conduction materials like the space shuttle tiles. It simply doesn't take too long at those speeds for the nose absorb more heat than it can take.
Re:Why so short bursts? by DerekLyons · 2010-05-27 06:32 · Score: 1

That's what datalinks are for.
Datalinks don't let you examine parts as specified by the OP. If you're using datalinks and not recovering the vehicle, there's no particular reason no to test the vehicle to destruction. (Assuming it has a safe descent path for the vehicle and/or the debris.)
Re:Why so short bursts? by magarity · 2010-05-27 07:22 · Score: 1

Allowing you to fire an obviously non-nuclear missile

That doesn't make sense; what about any given long range missile makes it "obviously non-nuclear"? From cruise missile to scud to icbm to a scramjet contraption, until it goes boom there's no "obvious" indicator of the warhead being nuclear, chemical, or leaflet.
Re:Why so short bursts? by MozeeToby · 2010-05-27 07:28 · Score: 1

Perhaps "not obviously nuclear" would have been a clearer choice of words. If China or Russia detect the launch of an ICBM they're first thought is going to be that it is nuclear tipped simply because that is all ICBM's are used for. In theory you could launch from an ICBM with a secondary guidance package on the warhead and land a conventional weapon within 10 ft of your target, but you're going to make a lot of people in a lot of governments very nervous when they see the ICBM launch signature. Is it entirely rational? No, but sense when do you expect the world to be rational?
Re:Why so short bursts? by Anonymous Coward · 2010-05-27 07:40 · Score: 0

Why are these engines burning for such short times? Are these engines so early in development that they really can't get them to be stable and safe for more than 12 seconds? Sounds a lot like fusion: it works but it's not yet useful.
Ummm... it was 200 seconds. at Mach 6 that's 254 miles. Not exactly practical to test beyond that at the moment I'm guessing.
Fun trivia: A flight from New York to London would only take 1 hour at mach 6
Re:Why so short bursts? by radtea · 2010-05-27 08:36 · Score: 1

They want to be able to say "Fire" and have the missile in the air within minutes and at target within hours; with the added benefit of not putting any American lives in harms way.
Sorry, you've lost me there. How does threatening or actually blowing people up NOT put Americans in harm's way? Your statement makes no sense.
The inevitable retaliation will kill Americans. The inevitable retaliation is inevitable.
So saying blowing people up in far off lands won't put Americans in harm's way is trivially false, like saying humans didn't evolve from apes or the equivalent: the product of a pre-scientific, anti-empirical understanding of how the world actually is.

--
Blasphemy is a human right. Blasphemophobia kills.
Re:Why so short bursts? by Grishnakh · 2010-05-27 09:20 · Score: 1

Huh? Why would you need refueling planes for modern bombers? I'm pretty sure we've had bombers for decades now which could fly easily between continents without refueling.
Fighter jets, OTOH, don't have much range and need refueling for many missions.
Re:Why so short bursts? by ImprovOmega · 2010-05-27 10:57 · Score: 1

This will never be a practical, money-making technology. It's almost as bad as fusion power.
I feel obliged to point out that when lasers were invented there was no real practical application for them (nor for a couple decades afterward), but now they are an indispensable part of our everyday life. From disc players to pointers, to industrial etchings and beyond we would not have half the cool gadgets we have without lasers. So, basically, don't knock the hard science stuff. It almost always comes out being useful in some way, even if we can't see the purpose of it yet.
Re:Why so short bursts? by Anonymous Coward · 2010-05-27 11:57 · Score: 0

Ah... speaking as someone with a PhD in materials science... moving or not, the intense heating and presumably dust hitting the jet pieces can cause significant damage.
Re:Why so short bursts? by Anonymous Coward · 2010-05-27 12:20 · Score: 0

Wear is definitely an issue at Mach 5. Dissonance begins at begins at this speed but localized air streams around the airframe are much faster then that.
http://www.youtube.com/watch?v=wHuBsBOF4R8&feature=related
Re:Why so short bursts? by gilgoomesh · 2010-05-27 12:24 · Score: 1

A Mach 6, wind resistance alone is like detonating explosives in the air intakes. Wear is certainly a serious issue.
But that's not what they're looking at in this case -- they're looking at getting the combustion to be stable and controlled. Wear and tear is something to sort out once the vehicle is less experimental.
Re:Why so short bursts? by Anonymous Coward · 2010-05-27 14:01 · Score: 0

The first lasers didn't burn out after 12 seconds and self destruct. The applications came faster than a "few" decades, they put a corner reflector on the Moon and shined a laser at it. That's less than 10 years.
How long have they been dicking around with scramjets?
Re:Why so short bursts? by A+nonymous+Coward · 2010-05-27 14:24 · Score: 1

Scramjets have no moving parts
They certainly do -- the air coming in at Mach 6 and the exhaust leaving even faster. There will be significant wear.

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Infuriate left and right
Re:Why so short bursts? by AK+Marc · 2010-05-27 16:19 · Score: 1

My understanding on range is that it's mostly measured from in-air refueling to the next needed one. Takeoff and climbing take a chunk of fuel, so the range is lowered if those are required. I seem to recall that refueling immediately after takeoff was standard procedure for the SR-71 and others of that nature.

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Learn to love Alaska
Re:Why so short bursts? by Anonymous Coward · 2010-05-27 20:34 · Score: 0

That was because the SR-71 leaked fuel like a sieve when it was on the ground due to the fact that the fuel tank wasn't watertight.
It required the heat caused by supersonic friction to make the materials in the fuel tank expand and seal.
I remember seeing it on discovery, the SR-71, sleek and deadly in the hanger, the pinnacle of aerospace technology with a bunch of beat up buckets sitting underneath it catching spilled fuel.
Re:Why so short bursts? by sewiv · 2010-05-28 02:29 · Score: 1

They can fly to another continent, yes, but after they bomb it, there aren't going to be allowed to land there. They have to fly back, too.
Re:Why so short bursts? by Ragnarr · 2010-05-28 03:32 · Score: 2, Interesting

If you think we can't launch aircraft within 24 hours and strike targets around the world, you're gravely mistaken. We have people whose jobs are to plan for missions such as this so that we can go out and do exactly that just by putting bombs on the planes and taking off. Not to mention that now days, with our capacities for SATCOM and other techniques, we're able to pass target information on the fly and build them in the air. As for the child thread below who wonders why we need air refueling; it's critical to all military operations. It's what sets us apart from all other air forces. Most aircraft are designed to take off with a certain weight, and getting that amount of stuff in the air usually is at the extreme end of an aircraft's capabilities. So, by fueling the aircraft just enough to take off and then refueling on the way you're able to take more hate to the bad guys. And, it extends the range of our aircraft. It's usually not comfortable, but most of our aircraft are capable of flying indefinitely if you can get them the gas to keep them there. Refueling is instrumental to our operations around the globe. Cheers!
Re:Why so short bursts? by LordLimecat · 2010-05-28 11:08 · Score: 1

But parent implied that this sort of thing would be useful for missiles. My point was that trying to get a scram jet configuration to work with a missile in order to get it to go fast is silly, as they already go fast and have very long range.

Well, by phyrexianshaw.ca · 2010-05-27 03:07 · Score: 1

I imagine this may have wonderful potential applications in commercial goods transportation, though it's still a few years off.

Re:Well, by Gilmoure · 2010-05-27 05:06 · Score: 1

Amazon's already having trouble delivering a coffee maker to me without cracking the carafe. Not sure about this.

--
I drank what? -- Socrates
Re:Well, by Anonymous Coward · 2010-05-27 05:42 · Score: 0

Uh oh, a Space Nutter. Do you think you need a coffee pot so urgently you can afford to pay 1000x the fuel costs vs. a normal plane? Are you high?

Thing that we told you about last week by fishexe · 2010-05-27 03:08 · Score: 1

...did what we said it was gonna do. Yawn.

--
"I don't care about the Constitution!" --Bill O'Reilly, November 17, 2009

Feedback by Anonymous Coward · 2010-05-27 03:09 · Score: -1, Flamebait

So, do you have a life, or do you just sit reading Slashdot so you can tell everyone the quality of your last fart? Because your comments have about the same value.

Now can the truth come out? by OzPeter · 2010-05-27 03:09 · Score: 1

About that other Mach 6 plane that was already developed The Aurora

--
I am Slashdot. Are you Slashdot as well?

Re:Now can the truth come out? by Anonymous Coward · 2010-05-27 03:28 · Score: 0

Not for another decade probably. There are other aspects of the Aurora that they probably still do not want revealed besides its propulsion.
Things like the heat-shielding needed, the avionics necessary when flying that fast, the mothership (fairly sure it gets drop launched), cooling systems, and probably a dozen things I haven't thought of.
Re:Now can the truth come out? by Idiomatick · 2010-05-27 03:57 · Score: 1

The aurora was made up because people couldn't believe all the cool shit that was being made until the end of the 70s when engineering died.
Re:Now can the truth come out? by Anonymous Coward · 2010-05-27 07:46 · Score: 0

Indeed.
I have seen what I'd guess to have been the "Aurora" fly.
It was in Nevada, while I was at a rest stop on the interstate.
Whatever it was, it was so fast it went from horizon to horizon in less
than 30 seconds. And it did leave the "doughnuts on a rope"
contrail. I tried to get a closer look at it with an 8-power Zeiss
monocular but it was so high that all I could see was the beginning
point of the contrail. In other words, it was flying VERY high. The same
monocular was able to clearly discern individual windows on commercial
airliners which were flying in the vicinity at the time. And the airliners were
probably between 30K and 35K feet altitude. I'd say the fast mystery
aircraft was at least 3 times higher, but that's just a guess.
Ok, so maybe it wasn't the Aurora. I guess it could have been some other
extremely fast aircraft. But the contrail was what caused me to believe that
it was the Aurora, because the pattern of the contrail is well known and was
described by Bill Sweetman in an article in Aviation Week.
Anyway, you can be sure "they" already have plenty of devices we aren't being told
about. The SR-71 first saw the light of day in 1957 / 58 and plenty of time has elapsed
since then for tricky things to have been developed out there in the desert. You don't have to
believe what I've written, of course, but I know I saw it.
Re:Now can the truth come out? by Iron+Condor · 2010-05-27 10:53 · Score: 2, Informative

There's as much concrete evidence the Aurora exists as there is evidence Bigfoot exists.

--
We're all born with nothing.
If you die in debt, you're ahead.

Sub-orbital transport dominates by Baldrson · 2010-05-27 03:10 · Score: 1

From the FX claim Sorb currently trading at a 10% chance of coming true:

Suborbital transportation will exceed high-mach air transportation by the year 2020. "Suborbital" means any high-mach, non-orbital flight where the majority of the distance is covered without benefit of locally available gasses as the primary propulsion reaction mass. "High-mach" means the majority of the distance is covered at a speed of mach 2.5 or greater. "Non-orbital" means the total flight path distance is less than the circumfrence of the earth. "Locally available" excludes gasses that have been stored within the vehicle for more than 3 minutes. The metric for comparison will include passenger, luggage and cargo ton-miles over the entirety of the year 2020 as published in standard industry surveys.

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Seastead this.

Re:Sub-orbital transport dominates by Gilmoure · 2010-05-27 05:08 · Score: 2, Informative

New Mexico's already building their space port. Will be interesting to see if sub-orb traffic takes off.

--
I drank what? -- Socrates

For those of you who don't know how fast Mach 6 is by viking099 · 2010-05-27 03:10 · Score: 3, Informative

From Wiki Answers:

Mach is a relative measurment of speed and fluid temperature.
example;
Mach 1 at Sealevel (0 feet) is 761.2 MPH (Calibrated Airspeed) and 761.2 MPH(True Airspeed)
Mach 1 at FL50 (Flight Level 50,000) is 285.8 MPH(CAS) and 660.05 MPH(TAS)
Mach 6 at Sealevel (0 feet) is 4567.3 MPH(CAS and 4567.3 MPH(TAS)
Mach 6 at FL50 (Flight Level 50,000) is 3147.97 MPH(CAS) and 3960.31 MPH(TAS)

So that's like going from Atlanta, Ga to Honolulu in just over an hour.

Waverider by Jeng · 2010-05-27 03:10 · Score: 4, Informative

So not only does this do Mach 6, but it also uses its own sonic booms to help with propulsion? Or did they just choose Waverider because it sounds neat?

http://en.wikipedia.org/wiki/Waverider

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Re:Waverider by bcmm · 2010-05-27 03:39 · Score: 5, Informative

So not only does this do Mach 6, but it also uses its own sonic booms to help with propulsion? Or did they just choose Waverider because it sounds neat?
It uses it's own shockwave for lift, not propulsion. This does, however, help it go faster, by eliminating the drag that adding wings would cause.

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Re:Waverider by Idiomatick · 2010-05-27 04:07 · Score: 4, Funny

They chose waverider since the US army sided with the autobot scum back in the 80s.

That's almost as fast as... by GeekZilla · 2010-05-27 03:11 · Score: 3, Funny

...how quickly my home declined in value in 2008 and 2009!

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Re:That's almost as fast as... by Anonymous Coward · 2010-05-27 04:19 · Score: 0

That's one hell of a quick Winnebago!
Re:That's almost as fast as... by Anonymous Coward · 2010-05-27 05:19 · Score: 0

Not nearly as fast as it appreciated in value from 2003 to 2006.
Re:That's almost as fast as... by tool462 · 2010-05-27 08:30 · Score: 1

And if the Global Warming scientists are right, it'll soon be in the ocean too--just like the scramjet!
Re:That's almost as fast as... by GeekZilla · 2010-05-27 10:13 · Score: 1

Guess the scientists were right because I am already underwater on the mortgage!

--
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FYI... by TrisexualPuppy · 2010-05-27 03:11 · Score: 0, Troll

flew autonomously for 200 seconds before losing acceleration

Google search query: 200 seconds * (mach 6) in miles

This brings us to about 254 miles in 200 seconds. Beats my morning commute speeds.

Re:FYI... by HopefulIntern · 2010-05-27 03:13 · Score: 1

Indeed. I need one of those for when I'm visiting the in-laws (or rather, when I am leaving).
Re:FYI... by muckracer · 2010-05-27 03:19 · Score: 1

> I need one of those for when I'm visiting the in-laws (or rather, when I am leaving).
No...you need one of those when you are flying with the in-laws. Personally I can't wait to see my mother-in-law's facial expression at Mach 6! >:-)
Re:FYI... by Anonymous Coward · 2010-05-27 03:28 · Score: 3, Insightful

Assuming the acceleration is modest, her facial expression aqt Mach 6 should be identical to when she's sitting on her living room sofa.
Re:FYI... by Hylandr · 2010-05-27 04:07 · Score: 1

Just buy a pair of tickets on a normal commercial flight and say as the jet is beginning it's take off roll, "Oh by the way, I hear this flight hits Mach 6." And watch her expression...

- Dan.

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Re:FYI... by Shakrai · 2010-05-27 04:12 · Score: 2, Funny

If she's like my mother in-law she'll look at you with a blank expression and say "What's Mach mean?"

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Re:FYI... by smitty777 · 2010-05-27 04:22 · Score: 1

Just keep in mind that the mach number will change based on the altitude of the aircraft (note the value C in the formula).

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Re:FYI... by ElectricTurtle · 2010-05-27 04:26 · Score: 2, Informative

Such epic pedantry does not deserve Troll moderation.

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Re:FYI... by Anonymous Coward · 2010-05-27 04:34 · Score: 1, Informative

Assuming the acceleration is modest, her facial expression aqt Mach 6 should be identical to when she's sitting on her living room sofa.
Considering it accelerated from a maximum of about 650 mph (290m/s - crusing speed of a B-52) to about mach 6 (2000m/s) in a period no greater than 200s, that gives an average acceleration of 8.75 m/s^2.
That's roughly equivalent to accelerating in a car from a dead stop to 60mph (100 km/hr) in about 3 seconds. So, in order to see this face, I suggest you take her for a ride in one of the following vehicles, pinning the accelerator to grant maximum acceleration:
Bugatti Veyron 16.4 (2.6s to 60)
Lamborghini LP670-4 Superveloce (3.1s to 60)
Koenigsegg CCX (3.1s to 60)
My bet is that it looks slightly different than when she's on the sofa.
Re:FYI... by Gravitron+5000 · 2010-05-27 04:55 · Score: 1

Not after I roll down the windows.
Re:FYI... by mindwhip · 2010-05-27 05:27 · Score: 0, Offtopic

Well thats what you get for buying a Russian bride who (and her family) can't speak English...

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Re:FYI... by Sique · 2010-05-27 06:36 · Score: 3, Insightful

Or you just lie flat on the earth and let gravity do about the same.

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Re:FYI... by Bobby+Mahoney · 2010-05-27 06:43 · Score: 2, Informative

Not to be a stickler, but mach is a relative number based on air density (altitude/pressure), so unless they tested the thing at 5' above the waves or something, it's more like 220 miles in that 200 second time frame (assuming 50,000 ft). That makes it way less cooler, I know.

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Re:FYI... by nabsltd · 2010-05-27 06:43 · Score: 1

Bugatti Veyron 16.4 (2.6s to 60) Lamborghini LP670-4 Superveloce (3.1s to 60) Koenigsegg CCX (3.1s to 60)
The new Audi R8 V10 is in the sub-four second 0-60 as well.
Re:FYI... by nitehawk214 · 2010-05-27 09:00 · Score: 1

Assuming the acceleration is modest, her facial expression aqt Mach 6 should be identical to when she's sitting on her living room sofa.
Not if she is on the outside of the craft. But then, a standard subsonic jet would probably suffice.

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Re:FYI... by Anonymous Coward · 2010-05-27 09:08 · Score: 0

Don't you need more info before you can convert mach 6 into a measure of speed that can be used to calculate a distance over time? Mach 1 at sea level is 761.2mph whereas mach 1 at 36,000ft is only 654.6mph.
Re:FYI... by dferrantino · 2010-05-28 05:20 · Score: 1

But that's too much!

Still a long way to orbit by Baldrson · 2010-05-27 03:11 · Score: 3, Informative

Mach 6 is still a long way from Mach 22. Mach 22 is orbital velocity.

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Re:Still a long way to orbit by sanosuke001 · 2010-05-27 03:19 · Score: 5, Informative

No it isn't. Mach is the speed sound travels in a medium (the atmosphere). As there is no atmosphere in orbit, you can't associate a mach speed value to orbital velocities.

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Re:Still a long way to orbit by batistuta · 2010-05-27 03:20 · Score: 1

orbital velocity of what?
Re:Still a long way to orbit by Baldrson · 2010-05-27 03:26 · Score: 1

Boy, ya learn something every day, don'cha?

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Seastead this.
Re:Still a long way to orbit by beelsebob · 2010-05-27 03:34 · Score: 1

It's entirely possible to do orbital velocities and not be in orbit... It tends to end up in being turned into smush, and/or being propelled out the atmosphere at some point, but that doesn't change the fact that it's possible.
Re:Still a long way to orbit by Anonymous Coward · 2010-05-27 03:37 · Score: 0

You can't really use Mach as a unit for orbital speed. The speed of sound varies depending on the medium it's traveling through.
It also depends on the altitude of the orbit. For Low Earth Orbit (LEO) you're looking at 6.9 - 7.8 km/s (using the wiki numbers here). That's 15435 - 17448 mph. If you felt the need to convert it to mach number, that would be mach 20-23, through air, at 20 degrees Celsius.
However, I don't think orbit is what they're looking to achieve (regardless of the article). More likely these engines would be developed for surveillance or weapons. In which case, they don't need orbit. They just need to get way up high and do it very fast.
Re:Still a long way to orbit by Waffle+Iron · 2010-05-27 03:42 · Score: 1

As there is no atmosphere in orbit
There's no fundamental reason why you couldn't orbit within the atmosphere at Mach 22, with the occupants experiencing weightlessness. We don't currently have the materials and engines to withstand such conditions, nor would it make any sense to try, but it could be done in theory.
Anyway back to the OP's point, since kinetic energy is proportional to the square of the velocity, Mach 6 is only 7% of the energy needed to reach orbit. IMO, scramjets are just a complex diversion if the goal is to go into orbit. (And you need to first reach supersonic speeds by yet some other means before you can even switch them on.) Reaching Mach 6 with an ordinary booster rocket stage is child's play in comparison.
Re:Still a long way to orbit by GeekZilla · 2010-05-27 03:44 · Score: 2, Funny

An unladen African Swallow?

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Re:Still a long way to orbit by Lumpy · 2010-05-27 03:49 · Score: 1

You just gotta keep pushing down on the stick..

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Re:Still a long way to orbit by Idiomatick · 2010-05-27 04:00 · Score: 2, Funny

Because in space no one hears you zoom pass them in your badass scramjet missile?
Re:Still a long way to orbit by interval1066 · 2010-05-27 04:06 · Score: 1

That brings up another point; I noticed that one of the applications they're pinning on this technology is for orbital launches. Being still a jet this engine requires air, so I'm pretty safe in assuming the application is for an assisted orbital target or as some kind of launch platform, right?

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Re:Still a long way to orbit by slaad · 2010-05-27 04:15 · Score: 2, Informative

The point is that mach 22 isn't a set speed. It depends on your altitude (or more specifically, the speed at which sound travels through your surroundings). If you're in orbit you could say that you're traveling the equivalent of mach 22 at an altitude of x feet, but you wouldn't actually be traveling mach 22. You can't express velocity in space using a mach number.

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Re:Still a long way to orbit by rossdee · 2010-05-27 04:50 · Score: 1

"No it isn't. Mach is the speed sound travels in a medium"
So what is the speed sound travels in a large?
"As there is no atmosphere in orbit, you can't associate a mach speed value to orbital velocities."
In low earth orbit there is a small amount of atmosphere, and the drag it causes is why stuff orbitting there can't stay up forever (like the ISS needs a boost from time to time.
Re:Still a long way to orbit by element-o.p. · 2010-05-27 04:50 · Score: 2, Funny

Crap. And I just bought the aftermarket exhaust cans for my personal scramjet, since they were advertised to have a way cooler than stock exhaust sound. At least you'll still be able to see the underbody lights I added as I zoom past...

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Re:Still a long way to orbit by Anonymous Coward · 2010-05-27 04:58 · Score: 0

You missed the point. Mach 6 at sea-level is a different "ground speed" than Mach 6 at 100,000 ft. So saying "Mach 6" without giving an altitude doesn't tell us very much.
Re:Still a long way to orbit by pavon · 2010-05-27 05:18 · Score: 1

Yep. For example, this flight was performed at 50,000ft which equates to 15.24 km above MSL. The orbital velocity at that altitude is 7.90 m/s, which at that air pressure equates to 26.8 Mach.
Of course, between the friction from air and the fact that orbital velocity decreases with altitude, it would be a better use of your energy to gain altitude then to increase horizontal speed.
Re:Still a long way to orbit by mosb1000 · 2010-05-27 05:31 · Score: 1

I'd imagine they're wanting to use the technology to propel missals through the atmosphere. In that regard, it is not a diversion. The claim that it's a step on the way to orbit is misleading, but you can't blame them for trying to come up with some pleasant sounding purposes for this technology.
Also, it seems like you could use this for sub-orbital space flight. Mach 6 is still really fast, and there's no friction in space.
Re:Still a long way to orbit by Anonymous Coward · 2010-05-27 05:49 · Score: 0

You're off by a factor of 10.
Orbiting is possible at ~100km. Atmosphere stops behaving like a gas at ~1000km.
Re:Still a long way to orbit by billybacs · 2010-05-27 06:19 · Score: 0

If you wanted to be incredibly pedantic, you could try to make the case that up there has negligible atmosphere, traveling 1m/s = Mach 9001 or something...I'm not sure if the molecules are still too far apart to even bounce into one another, though.
Re:Still a long way to orbit by Anonymous Coward · 2010-05-27 06:23 · Score: 0

African or European?
Re:Still a long way to orbit by ImprovOmega · 2010-05-27 06:45 · Score: 1

Well, honestly if you get get something up fast enough in the air the momentum would carry it into space. I mean, the pure speed needed for escape velocity is something like Mach 22, but you could go a couple hundred miles straight up after you hit atmosphere too thin to support your scramjet. Falling back could be a bitch though.
If you just wanted to lob things into orbit, you could do it with pure ballistic launches (with maybe some shielding to protect the payload from atmospheric friction). It would probably be cheaper and simpler to use a railgun launch platform to accelerate to escape velocity and let basic physics take it from there. Heinlen did a pretty decent treatment of the basic concepts in "The Moon is a Harsh Mistress".
Re:Still a long way to orbit by GooberToo · 2010-05-27 07:14 · Score: 1

are just a complex diversion if the goal is to go into orbit.
Not really. Remember a rocket carriers both fuel and an oxidizer. A ramjet uses atmosphere to obtain its oxidizer. Optionally, hybrid designs exist such that it switches to an on board oxidizer once the air becomes too thin. As rockets use the majority of their fuel to escape low high atmospheric densities, if one can spend the majority of their time accelerating without using on board fuel/oxidizer until absolutely required, TONS of fuel can be saved. Not to mention, it opens the door for much faster turn around given the relative simplicity (moving parts wise) of a ramjet.
In short, conceivably ramjets have the possibility to make orbital insertion, including higher orbits, faster, cheaper, safer with less pollution. While they may yet prove to be a "complex diversion", thus far they absolutely have a lot of unrealized potential.
Re:Still a long way to orbit by Anonymous Coward · 2010-05-27 08:07 · Score: 0

Not if it is air breathing, like this one was.
Re:Still a long way to orbit by bcrowell · 2010-05-27 08:12 · Score: 1

No it isn't. Mach is the speed sound travels in a medium (the atmosphere). As there is no atmosphere in orbit, you can't associate a mach speed value to orbital velocities.

Actually the GP was correct. Outer space is not a perfect vacuum, so sound waves can travel in it. The reason you can't hear in outer space is basically an impedance mismatch; the mechanism for turning vibration into sound, and then back into vibration, is extremely inefficient. Next thing to understand is that the speed of sound only depends on temperature, not pressure. Therefore the speed of sound in outer space is not drastically different from the speed of sound in the earth's atmosphere. I believe the temperature of the interplanetary medium in the vicinity of the earth's orbit is on the order of a cold night in Antarctica. So if you want to nitpick about the definition of mach factors, you're nitpicking the wrong variable. You should be nitpicking about temperature, not pressure -- and variations in temperature exist even within the earth's atmosphere, but that doesn't stop us from using mach factors to discuss speeds within the atmosphere.

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Re:Still a long way to orbit by Baldrson · 2010-05-27 12:24 · Score: 1

Now that we have Mr. Pedant's "critique" at (Warp:5, Informative), get a load of what NASA says about the X-15 program:

The effect of flight to Mach 1 produces large changes in the air pressures that support, retard, twist, pitch, roll, and yaw an airplane. But man edged past this speed into the realm of supersonic flight, and by the time Mach 1.5 was attained, airplanes had undergone a vast transition in technology. Some men saw in this transition the basis for pushing much farther up the flight corridor. In the early 1950's, a few visionary men looked far up that corridor and became intrigued by a goal much closer than the theoretical limit at the speed of light. They saw that the corridor flared dramatically upward at orbital speed (Mach 24), leading out of the Earth's atmosphere into space, defining the start of a path to the Moon, Mars, and beyond.

Now, I suppose Mr. Pedant is going to point out that Mach 22 is off by a whole 1539.35 mph.

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Re:Still a long way to orbit by jafac · 2010-05-27 12:58 · Score: 1

UN-informative.
Whether you're IN orbit, or NOT in orbit, has nothing at all to do with atmosphere. Except when atmospheric drag slows you down so that you can't maintain the velocity necessary to counter the gravity of the object you're circling.
Solve the propulsion and/or drag problem, and you can orbit the Earth at any altitude you like. Even negative altitude. Dirt's just a harder problem than air. A tad draggier.
In fact, I think the closer to the gravitational center you get, you start getting canceling effects (mass above and below). Theoretically, Newton says you can sit in the center of the earth and rest. It's the same as orbiting the earth, functionally.

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Re:Still a long way to orbit by Anonymous Coward · 2010-05-27 22:09 · Score: 0

Did the GP mean escape velocity?

Mach 5 - Not Mach 6 by Maddog+Batty · 2010-05-27 03:12 · Score: 5, Informative

Boeing announcement here:
http://boeing.mediaroom.com/index.php?s=43&item=1227

"In its first flight attempt, the Boeing [NYSE: BA] X-51A WaveRider today successfully completed the longest supersonic combustion ramjet-powered flight in history -- nearly three and a half minutes at a top speed of Mach 5."

My understanding is that it didn't reach the 300 seconds Mach 6 burn it was hoping for. 200 seconds and Mach 5 isn't all that bad though...

More here:
http://www.theregister.co.uk/2010/05/27/x51_first_shot/

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Re:Mach 5 - Not Mach 6 by Anonymous Coward · 2010-05-27 05:56 · Score: 0

Go Speed Racer, Go!

200 seconds at Mach 6... by metamechanical · 2010-05-27 03:12 · Score: 1

Mach 6 is a little over 2 km/s, for 200 seconds, is 400 km... so in 3 minutes and 20 seconds, the plane just about crossed over the equivalent of Pennsylvania, from east to west.

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Re:200 seconds at Mach 6... by joggle · 2010-05-27 03:17 · Score: 1

Well, that was its top speed. It would have taken some time for it to accelerate from the cruise speed of the B-52 up to mach 6 so it wouldn't have gone quite that far.
Still, it probably would have gone at least half-way across Pennsylvania.
Re:200 seconds at Mach 6... by groovelator · 2010-05-27 03:30 · Score: 1

How many football pitches is that?
Re:200 seconds at Mach 6... by rvw14 · 2010-05-27 06:31 · Score: 1

All of them.

Jet - Scramjet - And Questions! by Anonymous Coward · 2010-05-27 03:13 · Score: 4, Interesting

Jet engines still have propellers to compress air, into which the propellant is injected where this mixture then ignites.
Scramjets just use their immense speeds to do the compression with a funnel, but that also means they need more conventional means to reach these high speeds (such as getting a ride on a B52 plus gravity)

Questions

What is the fuel efficiency per kilometer traveled?
Can a scramjet reach escape velocity, or get close enough so that additional oxygen for the fuel doesn't make up more than half the payload?
Did they find a new way to lose heat at supersonic speeds? Otherwise these rides will remain short ones.

Re:Jet - Scramjet - And Questions! by Anonymous Coward · 2010-05-27 03:58 · Score: 0

Can a scramjet reach escape velocity, or get close enough so that additional oxygen for the fuel doesn't make up more than half the payload?
No. More precisely, a (sc)ramjet cannot work outside of atmosphere because it uses atmospheric resistance to provide compression.
Re:Jet - Scramjet - And Questions! by icebrain · 2010-05-27 04:07 · Score: 1

1. Hard to know without some performance figures... and those are probably classified, which means we won't see them. A little careful google usage could probably give you rough estimates for proposed designs, or at least the numbers from which to calculate it.
2. That was the plan for the X-30 at some point, but that never made it to the hardware stage. I would guess the answer would be no. Did a little research on scramjets as an undergrad, and I believe Mach 12-14 seemed to be the uppper limit.
3. The trick is in radiating that heat faster than it's being added. I would guess that they're using some kind of hot-structure approach with high-temperature materials on things like leading edges and all. The idea is to conduct the heat from the hottest parts of the airframe and conduct it into the rest of the structure. You have more mass to absorb the thermal energy, and more surface area to radiate from. This is the approach used by the SR-71 and X-15, and proposed for the X-20 and early space shuttle concepts.

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Re:Jet - Scramjet - And Questions! by Anonymous Coward · 2010-05-27 04:17 · Score: 0

First, you could reach escape velocity while still immersed in the atmosphere, or...

so that additional oxygen for the fuel ...
You only reach 50% of the speed, and then switch to your own oxygen (and close the input vents, or use a rocket engine) instead of using that inside the atmosphere. That still means you use less fuel, i.e. cheaper.
Re:Jet - Scramjet - And Questions! by Anonymous Coward · 2010-05-27 04:21 · Score: 0

This test used a rocket booster to get to hypersonic speeds, then it detached and the scramjet took it from there. I believe it was the same Orbital Pegasus first stage that they've used for previous hypersonic tests.
At 200 seconds, on a vehicle that small, they probably reached equilibrium temperatures. Often the plan is to dump heat into the fuel before burning it.
Re:Jet - Scramjet - And Questions! by Idiomatick · 2010-05-27 04:41 · Score: 1

"Can a scramjet reach escape velocity?"
No, you'd need multi-stage to escape. Without a revolutionary change in the tech anyways. As for weight I'm not sure but I think it might be good to point out that this is a riderless payloadless missile NOT a plane.

"Did they find a new way to lose heat at supersonic speeds?"
Apollo re-entry was about mach 30 (and the launches) so the tech is available to not be completely fucked at these speeds. But this is also related to the above question, good heat shielding or an active cooling system cost even more weight making the system bulkier and slower.

I think a spacecraft based on scramjet tech would look like a traditional Soyuz. Rocket launch (since scramjets don't work at low speed). The canisters drop off in prep for seconds stage where the scramjets kick in (mach 3~mach 15 up to the functional ceiling of the scramjets). Then the scramjet would drop off and the 3rd stage would kick in where again rockets would propel the craft into orbit. So really it wouldn't change the face of spaceflight. What we really need is a super light 3rd stage now and perhaps we could have a spacecraft that isn't a 1-shot. If it is light enough you could have the thing launched from the bottom of a fast plane (as the x-51 currently is) and then take itself to orbit.
Re:Jet - Scramjet - And Questions! by MartinSchou · 2010-05-27 05:14 · Score: 3, Interesting

Can a scramjet reach escape velocity
If it is capable of propelling whatever it's carrying to 11.2 km/s (just under Mach 33 at the Earth's surface). Since this one only goes to 6, there's still a ways to go.
Just as a foot note - if you're travelling at 11.2 km/s in a circle with a 6,378 km radius (Earth's equator), you will experience an acceleration opposite to gravity of 19.67 m/s^2 (aka 2 g). Just slightly slower if you do it at an altitude of 10 km (19.64 m/s^2). At the altitude this one reached, you'd hit 19.6 m/s^2
Re:Jet - Scramjet - And Questions! by BJ_Covert_Action · 2010-05-27 05:20 · Score: 5, Interesting

With regards to question 3, they have developed some pretty tricky ways to help cool the engines and the body of the vehicle. For instance, they cool the engines by circulating the JP-7 fuel through the body to absorb some of the heat to help bring it to the combustion point. This is very similar to how rocket nozzles are currently cooled to slow melting/failure:

The scramjet will circulate the fuel behind engine walls to cool the structures. Without such active cooling, the temperatures in a scramjet could reach 5,000 deg. Fahrenheit, high enough to melt virtually any metal on Earth. Solving the cooling challenge is a major AFRL/Pratt & Whitney achievement.
Source

My wager is that the entire vehicle took thermal control into its design considerations and it uses a combination of geometry, aerodynamics, and fuel management to help sink heat at an appropriately high rate to prevent too much for a build up. However, since I don't have the design specs, and I doubt anyone outside of the military will, for awhile at least, I can only speculate. You also have to understand that at those speeds, your gas dynamics become a problem of rarified gasses and heat management becomes a very tricky problem indeed, one that can't be approached by traditional cooling means. So in summation I would guess yes, they have probably found some very cool new ways to sink heat at hypersonic speeds.

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Re:Jet - Scramjet - And Questions! by blair1q · 2010-05-27 06:41 · Score: 4, Informative

Atmosphere isn't just compression, it's reaction mass. The compression creates the conditions for acceleration when the fuel is burned, but it's heating of the compressed air that causes the high force that accelerates the air backwards, accelerating the vehicle forwards.
You can bring your own oxygen, but it's just going to make a pretty flame coming out both sides of the combustion chamber unless there's mass flowing into the inlet and being pushed out through the nozzle.
I said this above already, but what you do here is you use a first-stage rocket motor to get up to scram-jetting speeds. Then the second-stage motor gets you to a certain point in the atmosphere where it loses thrust. Then you light your third stage.
This makes sense only if the specific impulse (look it up) from the scramjet exceeds that from a rocket motor, or it's ridiculously cheap and still gets the job done. I'm guessing it's not ridiculously cheap. But given that you don't have to bring the reaction mass for the scramjet with you, it might be more efficient than a rocket of the same mass. Meaning you can omit a heavy rocket motor and use a lighter scramjet and put the saved mass into the payload.
Re:Jet - Scramjet - And Questions! by blair1q · 2010-05-27 06:43 · Score: 1

I wonder if there aren't some ceramics that would laugh at 5,000F.
Re:Jet - Scramjet - And Questions! by Anonymous Coward · 2010-05-27 07:00 · Score: 1, Informative

On a technicality, scramjets are actually a little bit crazier than even what you said. A turbojet (basic jet engine) indeed uses compressor turbines to compress the air it ingests. A ramjet flies fast enough that it can use the shockwave travelling off a forward point of the engine to compress the air without needing to use a compressor. A scramjet is short for "supersonic combustion ramjet" and in a scramjet the air never slows down below the speed of sound inside the engine and must be able to sustain combustion in the supersonic domain. o.0
The engines of the SR
Re:Jet - Scramjet - And Questions! by Anonymous Coward · 2010-05-27 08:45 · Score: 0

The engines of the SR ... do continue! SR-71?! You can't leave us hanging here! Did someone knock on your door just now?
Re:Jet - Scramjet - And Questions! by Amanitin · 2010-05-27 08:47 · Score: 1

(such as getting a ride on a B52 plus gravity)
plus that tiny solid rocket booster which accelerates it to Mach 4.5, where the scramjet starts thinking about getting to business.
Re:Jet - Scramjet - And Questions! by Anonymous Coward · 2010-05-27 09:56 · Score: 0

I'd be curious as to electrical state transitions in the compression stage of the burn as the fluid changes from gas to plasma. If there were electrical probes across the intake and exhaust ends, how much current could be measured?
If it's significant and if you are clever enough, I'd bet that some well placed electromagnets (possibly superconducting) could also help with thermal management and boundary separation issues in the combustion chamber. That is, you could push things much further in your scramjet without having more exotic materials. (Hey it works to some extent for the Tokamak's and particle accelerators right? Why not?)
Re:Jet - Scramjet - And Questions! by PatrickThomson · 2010-05-27 11:08 · Score: 1

The important question is, How close can this get us to space? The concept can double the top speed of something like SpaceShip 1 (and I guess the top speed, being limited by air friction, goes up as you do) but you'd still need a rocket booster to make a stable orbit. It always struck me as incredibly wasteful to fill up all those rockets with propellant, and then use it from ground level. It was always ... odd to see the space shuttle consume vast quantities of booster fuel to hover stationary above the earth before pulling away slowly.

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Re:Jet - Scramjet - And Questions! by Anonymous Coward · 2010-05-27 13:17 · Score: 0

Laughing ceramics - this is the kind of idea I used to come up with when I'd get really high with my friends in college.
Re:Jet - Scramjet - And Questions! by MartinSchou · 2010-05-27 13:19 · Score: 1

It was always ... odd to see the space shuttle consume vast quantities of booster fuel to hover stationary above the earth before pulling away slowly.
I suspect that's simply because of the amount of outside air, you'd need to pull in to fuel the engines otherwise.
I only have enough of a clue of what it might involve to redo the calculations, that I know I haven't a clue. But I really do believe that available oxygen is the limiting factor.
NASA says they use 500,000 gallons of liquid hydrogen and oxygen. Liquid oxygen weighs 1141 g/L and 16 g/mol. This gives us 71.3125 mol/liter. That means for every litre of liquid oxygen we need 142.625 mol liquid hydrogen. Hydrogen is 1 g/mol and liquid hydrogen weighs 67.8 g/l so we need 142.625 grams of hydrogen which is 2.104 litres. So we have a 2.1:1 ratio.
This gives us about 162.000 gallons of liquid oxygen. That's 613,000 litres or about 43,523,000 mol of oxygen. Oxygen at surface pressure and 0C weighs 1.429 g/L. It's still 16 g/mol, so one litre of oxygen contains 0.089 mol. So we need 487.300.000 litre of pure oxygen. And since air only contains 21% oxygen, we'd need 2.320.000.000 litres of air, at 1 atmosphere and 0C.
It takes the shuttle 9 minutes to have spent all the fuel in the external tank. That means we're looking at around 4,296 m^3/s, just to supply that much oxygen. The three nozzles are 2.4 m in diameter. This gives us a total engine "surface area" of 13.6 m^2. If we assume the intake nozzles are the same size, the air would have to move at 316 m/s to supply it.
Obviously - if we remove 700 tons of liquid oxygen, we reduce the mass required and so on, and my back of the envelope here doesn't account for that. That's why we have rocket scientists.
But it's a fun thought.
Re:Jet - Scramjet - And Questions! by Rich0 · 2010-05-28 11:52 · Score: 1

But given that you don't have to bring the reaction mass for the scramjet with you, it might be more efficient than a rocket of the same mass.
It isn't just reaction mass - it is the oxidizer. 2g H2+ 16g O2 -> 18g H2O. In a rocket you carry that 18g of H2+O2 with you. In a scramjet you only carry the 2g of H2, and you use atmospheric O2.

I really don't have anything else to say... by f3rret · 2010-05-27 03:15 · Score: 0, Offtopic

I want one. Why? No reason other than the fact these sorts of things are pretty damn cool, even if they still kinda suck.

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So by drinkypoo · 2010-05-27 03:23 · Score: 1

When do we get a combination turbojet/ramjet/scramjet? Or will we be launching aircraft piggyback (or underwing) for the foreseeable future? This seems like a great technology for amazingly pissed-off artillery shells, I can imagine a ramjet that turns into a scramjet pretty easily if it doesn't have to turn back.

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Re:So by gimmebeer · 2010-05-27 04:23 · Score: 2, Insightful

The SR-17 had a combo turbojet/ramjet engine, it's forseeable that an updated engine could make the ramjet-scramjet leap.

Amazing by maillemaker · 2010-05-27 03:28 · Score: 4, Interesting

It's amazing to me that they can make a machine who's parts are GLOWING they are so hot and the metal still functions without failing.

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Re:Amazing by characterZer0 · 2010-05-27 03:33 · Score: 5, Funny

Like incandescent light bulbs?

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Re:Amazing by operagost · 2010-05-27 03:42 · Score: 1

Now I know why the green movement REALLY wants us to get rid of incandescent bulbs. Clearly, they're dangerous and could explode at any time!

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Re:Amazing by Anonymous Coward · 2010-05-27 03:44 · Score: 0

That's not glowing metal. That's just what ZPMs look like.
I'm not the only one that sees a giant ZPM, am I?
Re:Amazing by Cyberax · 2010-05-27 03:48 · Score: 1, Offtopic

You may laugh, but I did have a lightbulb explode above me. Picking out shards of glass out of my hair is not what I'd call 'fun'.
Re:Amazing by BobZee1 · 2010-05-27 03:50 · Score: 2, Interesting

The company I work for makes the parts in what "they call" the hot section of the engine. These are some really awesome materials. I fly a desk so I don't get to play with the goodies.

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dumber people are doing harder things everyday
Re:Amazing by newcastlejon · 2010-05-27 04:11 · Score: 1

I know you're being facetious, but the low-pressure inert gas is a real boon when things are white hot...

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Re:Amazing by Shakrai · 2010-05-27 04:15 · Score: 1

If it was a CFL you'd also be fishing mercury out of your hair.....

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We are the United States Government! We don't do that sort of thing.
Re:Amazing by RobVB · 2010-05-27 04:21 · Score: 3, Funny

You fly a desk and complain about the goodies? Your company must have some Awesome goodies.
Just out of curiosity, what's the air-speed velocity of your unladen desk?
Also, describe some of those goodies to me.

--
I'd rather you rationally disagree than irrationally agree.
Re:Amazing by Cyberax · 2010-05-27 04:57 · Score: 1

Mercury is a gas in CFLs, and its amount is too small to worry about it.
Re:Amazing by Gravitron+5000 · 2010-05-27 05:01 · Score: 1

Curse you! And double curse my sweet tooth!
Re:Amazing by Anonymous Coward · 2010-05-27 05:05 · Score: 0

Given the speed they are supposed to be moving, I would expect them to be a bit more air-cooled outside of the lab.
Re:Amazing by Machtyn · 2010-05-27 05:14 · Score: 1

Multiply that negligible amount by several 10's of thousands in our landfills. Now it's not too small to worry about.
Re:Amazing by Cyberax · 2010-05-27 05:18 · Score: 1

Still way too small. Also, elemental mercury and most of mercury compounds are not that dangerous for the environment.
For example, ores with a lot of mercury are pretty common: http://en.wikipedia.org/wiki/Cinnabar
Re:Amazing by santiagodraco · 2010-05-27 05:24 · Score: 1

Light bulbs work because they are filled with an inert gas NOT air. So your analogy does not apply here.
Re:Amazing by Anonymous Coward · 2010-05-27 05:50 · Score: 0

It may indeed be too small, but I simply don't believe you when you say that mercury and friends are not dangerous. Cinnabar is toxic.
From the MSDS: http://msds.chem.ox.ac.uk/ME/mercuric_sulphide.html
Environmental information
Mercury salts are harmful in the environment.
Re:Amazing by couchslug · 2010-05-27 06:08 · Score: 1

"It's amazing to me that they can make a machine who's parts are GLOWING they are so hot and the metal still functions without failing."
There are a fair number of glowy bits, but the majority of hot section internals are protected by a continuously replenished blanket of high pressure air excess to that required for combustion.

--
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Re:Amazing by GameboyRMH · 2010-05-27 06:18 · Score: 3, Funny

Just out of curiosity, what's the air-speed velocity of your unladen desk?
And, GP, do you have the European or African market version?

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Re:Amazing by $RANDOMLUSER · 2010-05-27 06:20 · Score: 1

Yeah, because there isn't any naturally occurring mercury. Oh, wait...

--
No folly is more costly than the folly of intolerant idealism. - Winston Churchill
Re:Amazing by longacre · 2010-05-27 07:06 · Score: 2, Funny

But they're SOOOO YUMMY.

Oh, I thought you said Cinnabons.

--
Airplane Photos, Airline News, Planespotting Guides
Re:Amazing by ashidosan · 2010-05-27 07:14 · Score: 0

Those several tens of thousands of CFLs didn't fall on his head simultaneously, either.
Re:Amazing by LanMan04 · 2010-05-27 07:22 · Score: 1

Here are a few examples of glowing manifolds/headers/etc in various automobiles. Not as amazing, but still, they work!
http://media.photobucket.com/image/glowing%20hot%20manifold/boardinscotland/euro4dyno.jpg
http://car-news.roadfly.com/wp-content/uploads/2007/03/glowing-bmw-m-v8-headers.jpg
http://image.automotive.com/f/tech/14916119+pheader/turp_0902_01_z+shot_peening_wpc_treatment+glowing_exhaust_manifold.jpg
http://badger-5.com/bin/glowing-turbo.jpg

--
With the first link, the chain is forged.
Re:Amazing by Grishnakh · 2010-05-27 08:49 · Score: 1

Like other toxic metals, such as lead, mercury "occurs naturally" deep underground, in very low concentrations in a material called "ore". It isn't found in pure, elemental, concentrated form above the ground where it can interact with the environment. It's only when humans dig it up, process the ore, and make it into a more pure form that it becomes dangerous.
Re:Amazing by Hazelfield · 2010-05-27 10:05 · Score: 1

Just out of curiosity, what's the air-speed velocity of your unladen desk?
And, GP, do you have the European or African market version?
I don't know that!
Re:Amazing by Anonymous Coward · 2010-05-27 11:02 · Score: 0

Careful production of metal alloys can create materials with no grain boundaries. These materials, while having about the same melting point as normally produced alloys, do not soften much until just before they melt. Normal metal alloys soften over a relatively long temperature range so that dimensional stability is compromised long before the alloy actually melts.
Re:Amazing by Tubal-Cain · 2010-05-28 07:04 · Score: 1

I see it, though ZPMs don't usually have a ~10m torch flame coming out one end.

2025 by Baldrson · 2010-05-27 03:29 · Score: 1

The orbital velocity of the year 2025, what else?

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Seastead this.

Test Terminated ? by willyg · 2010-05-27 03:29 · Score: 1

O.K., and the test was terminated WHY?? Thermal issues? Ran out of fuel? Test Design limit? Or is it classified?

No, I DIDN'T RTFA. Hello, this is /. ...

Re:For those of you who don't know how fast Mach 6 by vlueboy · 2010-05-27 03:37 · Score: 5, Interesting

Mac 5 melts aluminum steadily
Mac 6 melts steel

And don't forget that keeping this friction heat down also requires a good deal of power.

orbital velocity by Anonymous Coward · 2010-05-27 03:38 · Score: 0

is anything greater than zero if you are propelling yourself

Re:orbital velocity by Anonymous Coward · 2010-05-27 03:48 · Score: 0

I meant escape velocity of course
Re:orbital velocity by Anonymous Coward · 2010-05-27 05:05 · Score: 0

Smartass :P
This probably means an orbit which does NOT intersect with earth again 1 or 2000 seconds layer. Also, I am sure escape velocity is too much already, so orbital velocity indeed!

Nicely put. by archer,+the · 2010-05-27 03:47 · Score: 1

Now, where'd I put those marshmallows...

Re:Nicely put. by PotatoFarmer · 2010-05-27 04:28 · Score: 1

I see what's left of three of them at the end of your sentence.

makes me sad.... by Anonymous Coward · 2010-05-27 03:48 · Score: -1, Flamebait

so much energy squandered on killing people we don't get along with. Hell, most of that cold war junk never got used (thank ghod!) hopefully spin-offs and unintended side-effects can make some positive contribution to society.

Re:makes me sad.... by SnarfQuest · 2010-05-27 04:05 · Score: -1, Offtopic

There's your typical Democrat. Hates anything military, unless it can be used for abortions.
Most of that "evil" cold war junk convinced many other nations that attacking us would be a very bad idea. Terrible that, seeing that we didn't get the chance to kill them all when they invaded. Awful thing, deterrence. Maybe we should invade Mexico and Canada, just so we can kill them all.
We should just meekly follow your path, destroy our military, and wait for some tiny country like Panama to invade us, enslaving or killing us all. Only then will you be truely happy.

--
Who would win this election: Andrew Weiner vs Andrew Weiner's weiner.
Re:makes me sad.... by Shakrai · 2010-05-27 04:14 · Score: 1

and wait for some tiny country like Panama to invade us
That might be easier said than done.....

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I want peace on earth and goodwill toward man.
We are the United States Government! We don't do that sort of thing.
Re:makes me sad.... by Anonymous Coward · 2010-05-27 04:40 · Score: 0

Iraq likely had more guns -- excuse me, assault rifles -- and look where that got them. Defeated in days, with erratic and uncoordinated and logistically ineffectual resistance after the invasion.
I find that answer amusing, because of the hundreds of people I know in the city, only a handful possess guns. I suspect that 1:4 possession figure is being highly generous. It probably varies per state, but I imagine the discrepancy comes from the people who own 10 or more guns.
Furthermore, pistols aren't a threat to a military force. A pistol is useless on the battlefield, and noneffective against equipped personnel. "Gun" count is irrelevant. You should be looking at high-powered rifles, mines, and anti-armor weaponry. And these are universally banned within the US.
(Btw, I am not the hyperbolic GP.)
Re:makes me sad.... by Bakkster · 2010-05-27 05:14 · Score: 1

Scramjets aren't purely used for missiles. As with any other rocket, it's possible they could be used to reach orbit, but a scramjet could conceivably do it lighter and on less fuel (and thus cheaper).

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Re:makes me sad.... by Anonymous Coward · 2010-05-27 05:47 · Score: 0

I find that answer amusing, because of the hundreds of people I know in the city, only a handful possess guns. I suspect that 1:4 possession figure is being highly generous. It probably varies per state, but I imagine the discrepancy comes from the people who own 10 or more guns.
Five out of six households in the US do not own a single firearm. Households. The national median household size in the US is 2.57 Of course the sixth household, that consists of the one deranged loner libertarian slashdot troll with 15 guns does tend to skew the statistics.
Re:makes me sad.... by h4rr4r · 2010-05-27 05:58 · Score: 1

These are not banned. Even a lowly 30-06 is enough of a high powered rifle to defeat common body armor, its descendant .308 is a higher pressure NATO 7.62x51.
Mines and anti-armor weaponry are destructive devices and with proper permits can be legally owned.
Re:makes me sad.... by Anonymous Coward · 2010-05-27 05:59 · Score: 0

If you think ti takes less energy to find a way to coexist peacefully with people who don't like you very much than to simply kill them, then I think you have never met another person in your life.
Re:makes me sad.... by Shakrai · 2010-05-27 06:16 · Score: 1

You should be looking at high-powered rifles, mines, and anti-armor weaponry. And these are universally banned within the US.
There isn't a single American jurisdiction that bans "high-powered rifles", so I must conclude that you have no idea what you are taking about.

--
I want peace on earth and goodwill toward man.
We are the United States Government! We don't do that sort of thing.
Re:makes me sad.... by Tawnos · 2010-05-27 06:53 · Score: 1

So you're saying that people should stock up on Mosin Nagants from their local Big 5 for $100 each after tax?
"High-powered rifles" being universally banned my ass.
Re:makes me sad.... by phayes · 2010-05-27 07:36 · Score: 1

Scramjets are never going to be of any use in attaining orbit. The accelleration is poor, tops out much too early and are dead weight for the rockets that are really what is needed. As sustainer motors for hypersonic missiles, however they appear promising.

--
Democracy is a sheep and two wolves deciding what to have for lunch. Freedom is a well armed sheep contesting the issue
Re:makes me sad.... by Grishnakh · 2010-05-27 08:38 · Score: 1

Not true. It depends on your definition of "high-powered". 50BMG rifles, such as those made by Barrett, are indeed banned in some jurisdictions. Compared to a 50BMG, your typical 30-caliber rifle (even the really hot ones) is "low-powered".
Of course, the previous guy is still talking out his ass, as they most certainly are not "universally banned".
I do believe, however, that anything significantly more powerful than 50BMG (such as 20mm) is regulated by the BATFE and classified not as a "rifle", but as a cannon.
I don't think he's right about the mines and anti-armor weaponry either. One gun shop near me used to have an RPG on display. I believe it's possible to own such weapons, but it's very hard and gets a lot of scrutiny from the BATFE.
Re:makes me sad.... by chadplusplus · 2010-05-27 14:03 · Score: 1

Perhaps the cities would fall, sure. Fortunately, all those redneck skills/traits for which we hillbillies are typically mocked will certainly slow down any would be invader once they reach the Appalachians.
Re:makes me sad.... by Tubal-Cain · 2010-05-28 06:59 · Score: 1

...coexist peacefully with people who don't like you very much...I think you have never met another person in your life.
Or at least has never been stuck for a prolonged period of time with one of those people that don't like him.
Re:makes me sad.... by treeves · 2010-05-28 09:48 · Score: 1

I always liked the saying that "Alcohol, Tobacco, Firearms and Explosives" should be the name of a store, not the name of a government agency!

--
...the future crusty old bastards are already drinking the Kool-Aid.

ummm by AnAdventurer · 2010-05-27 03:52 · Score: 1

I thought the unpublished speed of the SR-71 was around Mach 6? Supposedly my brother met a 71 pilot who said he could fly over LA-NYC in like 40 minutes (at alt and speed). I am not saying any of that is fact, just something I remember from 25 years ago (living near Hamilton AFB)

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Re:ummm by gimmebeer · 2010-05-27 04:27 · Score: 1

The published top speed is Mach 3.2, but the theoretical (not sure if it's been proven) top speed of a ramjet engine is around Mach 5. The SR-71 used a hybird turbojet/ramjet engine, so assuming the airframe could support it, Mach 5-ish may have been possible.
Re:ummm by painandgreed · 2010-05-27 04:35 · Score: 1

I thought the unpublished speed of the SR-71 was around Mach 6?
The key bit here is not the speed but rather than it was a scramjet. The SR-71 may have even been faster but there is no chance that such a craft with those jet engines could ever reach orbit. Scramjets, once fully developed, should be able to or at least get us closer to it. As TFA says, this is like the step of going from prop driven aircraft to jet aircraft.
Re:ummm by Animats · 2010-05-27 05:00 · Score: 1

I thought the unpublished speed of the SR-71 was around Mach 6?
No, top speed of the SR-71 was around Mach 3.2, which it could sustain for hours. The absolute top speed ever achieved was 2,193.2 mph. The Museum of Flight at Boeing Field has had a SR-71 on display for years, and they have all the documentation.
The SR-71 powerplant is a turbojet that converts to a ramjet at high speeds.
When Kelly Johnson was designing the SR-71, they considered a liquid hydrogen propulsion system that might have made it to Mach 6 and beyond. Work on liquid hydrogen engines was conducted at Burbank. (That helped out NASA later on.) But they figured out how to do the necessary job with far less volatile fuels.
Re:ummm by mcgrew · 2010-05-27 06:59 · Score: 1

Airman Magazine, a USAF propaganda tool published for USAF servicepeople by the USAF had a story some time between 1971 and 1973 (When I was stationed at Dover) that claimed that an SR-71 flew from New York to England in 45 minutes, fifteen minutes of that at tanker speed for refueling.
I think it was probably bullshit, published to scare the Russians, but was probably where the rumors came from.
I was stationed at Beale in 1975, and they had nine SR-71s there, and I can tell you those are some incredible machines. It would roll down the runway picking up speed, do a wheelie, and disappear -- it looked like a bottle rocket taking off, not the slow lifting of a Space Shuttle, just WHOOOOOM and it was gone.
As incredible as those were, I seriously doubt they would do mach 6, but watching one take off would tend to make one think it could do damned near anything.

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Free Martian Whores!
Re:ummm by PeterM+from+Berkeley · 2010-05-27 08:11 · Score: 1

The post you replied to was referring to the often-heard claim that the Air Force has kept the true maximum speed of the SR-71 a secret. I have not heard any credible report about whether the Mach 3.? number that is acknowledged is actually correct. I suppose some Soviet radar operators would know, in addition to the people in the US Government who know.
--PeterM

Didn't hit mach 6, just mach 5! by PeterM+from+Berkeley · 2010-05-27 03:56 · Score: 5, Informative

Hello,

The story is in error. Per this link, the plane only hit Mach 5, not Mach 6. This is still a pretty successful test, however.
Link: http://www.msnbc.msn.com/id/37377401/ns/technology_and_science-space/

--PeterM

Re:Didn't hit mach 6, just mach 5! by slaad · 2010-05-27 04:22 · Score: 2, Interesting

Most sources seem to be reporting mach 5, but that msnbc article is rather funny. The caption by the picture says mach 6 and then the article itself says mach 5.

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Re:For those of you who don't know how fast Mach 6 by Anonymous Coward · 2010-05-27 03:58 · Score: 1, Funny

...and Mac 7 gave us the integrated Multifinder.

Scramjet Hits Mach 6, Sets Record by Anonymous Coward · 2010-05-27 04:10 · Score: 0

Sure - they have been flying mach 10++ for 20 years now. Those projects are still classified. We found out about the SR71 when it was ready for mothballs, we saw the F117 and B2 stealth tech 15 years after it had been flying. I'm sure slashdot will be the first to know about new speed records set by the USAF.

Re:For those of you who don't know how fast Mach 6 by vlueboy · 2010-05-27 04:22 · Score: 1

...and Mac 7 gave us the integrated Multifinder.

Oops. I should have spelt Mach right :)
Thanks!

Re:For those of you who don't know how fast Mach 6 by JMZero · 2010-05-27 04:23 · Score: 5, Funny

Even at Mach 3, you want a layer of foam to avoid burning.

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Let's not stir that bag of worms...

Correct - 0.1 G by Mathinker · 2010-05-27 04:27 · Score: 1

Yes, accelerating from Mach 4.5 to Mach 5 in 200 seconds is only about 0.1 G.

Probably the acceleration to Mach 4.5 using the rocket engine, however, was much higher.

there *is* atmosphere by SuperBanana · 2010-05-27 04:28 · Score: 2, Informative

No it isn't. Mach is the speed sound travels in a medium (the atmosphere). As there is no atmosphere in orbit, you can't associate a mach speed value to orbital velocities.

You start out in the atmosphere, chief. Also, Wikipedia specifies a Mach number for LEO.

Even in LEO, there is air- it's just very, very, very thin. The atmosphere doesn't end at a hard line.

Why do you think objects in LEO gradually slow down and re-enter? Answer: aerodynamic (and solar) drag.

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Please help metamoderate.

Re:there *is* atmosphere by Anonymous Coward · 2010-05-27 12:55 · Score: 1, Insightful

Also, Wikipedia specifies a Mach number for LEO [wikipedia.org].

If it's on the internet, it must be true!

Glowing metal = black body radiation by spineboy · 2010-05-27 04:31 · Score: 4, Informative

The temperature of objects produces (from what i recall of physics) black body radiation - meaning it produces light wavelengths. Just because we associate melted iron being red hot, doesn't mean other metals melt when they start to glow. It just means they are hot enough to produce enough black body radiation that we can see. Look at mercury for example as an opposite.

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..........FULL STOP.

Re:Glowing metal = black body radiation by dbIII · 2010-05-27 12:32 · Score: 1

Also red hot iron is still a very long way from melting.
That's easy to see with a fire that has no hope of melting iron, a bit harder to see with an oxy torch or plasma cutter where the temperatures you can produce are well beyond the melting point.

Bussard Ramjet by Gothmolly · 2010-05-27 04:41 · Score: 1

Call me when we have a Bussard Ramjet.

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logical fallacy by SuperBanana · 2010-05-27 05:00 · Score: 1

Whether or not you agree with it, military research has led to an enormous number of scientific advances that were initially used by the military but later disseminated more broadly. Jet engines, the Internet, cryptography, GPS, nuclear reactors, etc.

You're using a logical fallacy, namely that if the military research hadn't happened, these technologies never would have been developed...

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Please help metamoderate.

Re:logical fallacy by mdarksbane · 2010-05-27 05:15 · Score: 2, Insightful

It is almost assured that they would have happened later, though, since they didn't beat the military research to begin with.
Re:logical fallacy by radtea · 2010-05-28 02:08 · Score: 1

It is almost assured that they would have happened later, though, since they didn't beat the military research to begin with.
Why do you say that? We're talking about counter-factuals. In MY imaginary dream world where people are on average somewhat smarter or perhaps just more humane than they actually were, historically, rather than spending billions and billions of dollars on the deadweight loss industry to develop these technologies, they were developed instead by massive expenditure of tax dollars for the exploration of space.
And in this imaginary alternate universe all of these technologies and more besides were developed sooner because some of the people who were responsible for it didn't die senselessly in bombings or on battlefields, and some of the labs and factories where it was worked on weren't blown to bits.
The benefits of massive public expenditure on new technology should be sufficiently obvious that it does not need to be coupled to deadweight loss spending of the kind the military specializes in.

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Blasphemy is a human right. Blasphemophobia kills.

No good by SnarfQuest · 2010-05-27 05:11 · Score: 1

This thing won't be very useful until it looks as evil as the SR-71.

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i find that hard to believe by circletimessquare · 2010-05-27 05:13 · Score: 0, Offtopic

they would spend billions on a potentially game-altering piece of technology and just let it drop into the open ocean and forget about it?

where any nation with a submarine can retrieve it and copy it?

i can't believe that to be the case

--
intellectual property law is philosophically incoherent. it is your moral duty to ignore it or sabotage it

Re:i find that hard to believe by dpilot · 2010-05-27 06:13 · Score: 1, Funny

The ones that work look nothing like these, we won't hear about them for 20 years, nor will the enemy get their hands on them.
These are the tests we hear about. We WANT the enemy to find them, reverse engineer them, and copy them. Looking at these test vehicles will set them back YEARS!

--
The living have better things to do than to continue hating the dead.
Re:i find that hard to believe by h4rr4r · 2010-05-27 06:20 · Score: 2, Funny

How much do you think is left after it hits the sea at Mach 6?
Re:i find that hard to believe by GameboyRMH · 2010-05-27 06:35 · Score: 1

The vehicle itself is a small part of the overall budget. As for being picked up by foreign submarines, it's gonna hit the water at a pretty decent speed, so even if any big pieces are left it'll be too mangled to be of any use.

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Re:i find that hard to believe by caluml · 2010-05-27 08:09 · Score: 1

The same amount?

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Re:i find that hard to believe by Pharmboy · 2010-05-27 08:32 · Score: 1

That's pretty funny. Yes, the act of accelerating doesn't change the mass, assuming we aren't approaching the speed of light. There would be a slight increase in the discreet number of pieces after it hits the ocean, however.
I still don't like the idea of not getting the test platform back. Some museum would be happy to show one of these someday, after 20 or 30 years when the technology is less classified. And you would have to think that they would get more info by putting their hands on the spent vehicle. There is no way you can have sensors for every square inch of the platform. The idea that they ditch and forget the platform just doesn't sound right.

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Re:i find that hard to believe by dbIII · 2010-05-27 12:45 · Score: 1

You spend billions working out how to shape the bit of metal and then a couple of thousand making the part.
A scramjet is just a metal nozzle with some sort of fuel feed into it. It is also not likely to differ greatly from the civilian versions it is based upon such as Hyshot so industrial/military espionage of the fragmented wreckage probably won't help anyone much.
The basic shape is the same as the one I first saw in 1987, it's a matter of refinement and a lot of tests because there really are not any mathematical models of hypersonic fluid flow that are good enough to do it all with simulation. I am not a rocket scientist, just an engineer that used to do things in the same building.

in the fall? by circletimessquare · 2010-05-27 05:19 · Score: 4, Funny

you mean in the autumn?

or in the spectacular screaming descent towards land?

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Re:in the fall? by Anonymous Coward · 2010-05-27 23:00 · Score: 0

He may have meant the action that led to the universe becoming unaligned with God's wishes or commandments.

The Russians are there already by Anonymous Coward · 2010-05-27 05:31 · Score: 0

AYAKS

What happens at Mac 10? by hackingbear · 2010-05-27 06:02 · Score: 1

Mac 6 melts steel

Oh... I'm running on Mac 10, no doubt the economy is burning!

Re:For those of you who don't know how fast Mach 6 by DarthVain · 2010-05-27 06:26 · Score: 1

It reminds me (and relevantly so for a change) of the Blackbird spy plane.

Apparently it leaked fuel like a sieve when on the ground, because none of it fit together tightly. However when it got up to speed, the metal would heat up and expand, tightening up everything. This was apparently part of the actual design.

So yeah, go fast enough and you start running in to some pretty intense material engineering problems that need to get figured out, just to keep from vaporizing, never mind how weird things like that fly from a aerodynamical point of view.

I think a more obvious example of what is going on at high speeds is some of the work to get faster torpedoes in subs. From what I understand (which isn't much) hyper-cavitation creating a void at the front of the torpedo to enable it to cut through the water faster is the same principle as these ultra high speed air tests, where the air is removed from the nose of the test plane, reducing drag and friction, and most importantly heat, due to the later which would be beyond the material's ability to absorb and not deconstruct.

Re: by clint999 · 2010-05-27 07:30 · Score: -1

If she's like my mother in-law she'll look at you with a blank expression and say "What's Mach mean?"

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Re:For those of you who don't know how fast Mach 6 by Anonymous Coward · 2010-05-27 07:47 · Score: 0

Me and my homies prefer the Mac 11 for drive-bys.

Re:For those of you who don't know how fast Mach 6 by Anonymous Coward · 2010-05-27 08:37 · Score: 0

What does Mac (os) X melt?

Obligatory automotive analogy: by Anonymous Coward · 2010-05-27 09:00 · Score: 0

Why is that exactly? Sure, the J58 is a unique engine, but we've since made engines for airliners that put out three times as much thrust.

Why is that exactly? Sure, the BRM V16 is a unique engine, but we've since made engines for lorries that put out three times as much torque.

Re:For those of you who don't know how fast Mach 6 by Jeff+DeMaagd · 2010-05-27 10:09 · Score: 1

Power is a major problem. That's why I'm not putting hopes on supersonic passenger flight. Transatlantic supersonic flights costed $10,000 a ticket, $300 for regular subsonic travel.

The power to overcome drag in a fluid is supposed to be related to speed to the third power. Mach 2 would require 8 times more power than mach 1. Mach 6 should require 216 times the power as mach 1. Given the cost of fuel, I don't see a lot of people being willing to pay 200x as much to save a few hours of flight time.

Not a record: X-43A hit Mach 9.6 in 2004 by tlambert · 2010-05-27 10:19 · Score: 1

Not a record: X-43A hit Mach 9.6 in 2004

http://news.bbc.co.uk/2/hi/science/nature/4018117.stm

Quoting Randy Vorland on the X-43A test flight:

I think it's easier than people think it is. We can really do this stuff. I don't mean to make it sound too easy, but it's definitely doable.

-- Terry

Re: by clint999 · 2010-05-27 20:30 · Score: -1

Perhaps the cities would fall, sure. Fortunately, all those redneck skills/traits for which we hillbillies are typically mocked will certainly slow down any would be invader once they reach the Appalachians.

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Legal Caliber limits, according to Geneva by Terje+Mathisen · 2010-05-28 05:46 · Score: 1

In my (drafted) military service here in Norway, I was told that the legal limit for weapons used for "directly aimed fire against personnel" was 12.7 mm, aka .50 cal.

Not by coincidence, .50 is of course the most popular cailber for long-range sniper rifles.

That meant that the 20 mm anti-aircraft gun I commanded could be used against helicopters, trucks and cars in addition to regular aircraft, but not against unmounted infantry.

Terje

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Re:For those of you who don't know how fast Mach 6 by Anonymous Coward · 2010-05-28 06:48 · Score: 0

Which is faster, a submarine or a race boat? Notice how the race boat is specifically designed to skim over the top of the water instead of dragging through it. All modern airplanes are air-submarines. This engine could allow the development of a completely different type of vehicle...an air skimmer. The drag goes away, and you get more speed and actually use LESS fuel.

Not useful for space launch by Anonymous Coward · 2010-05-29 01:05 · Score: 0

Scramjets are a cruise technology, not an acceleration technology. Note that they need rockets to get up to speed and are limited to a narrow speed range.

Space launch is a short time acceleration mission.

It's just marketing talk saying they would be useful, yet every editor swallows it whole. Maybe scramjets can cure the common cold too so the voters should give more money to Boeing etc...

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USAF Scramjet Hits Mach 6, Sets Record

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