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Space Science

X-43A Hits Mach 7 405

quiggy writes "As previously reported, NASA tested the X-43A yesterday. The results are in, and the scramjet hit Mach 7, setting a new speed record. CNN is also reporting the story, with a note that a similar jet could be tested by the end of the year, hopefully reaching Mach 10."
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X-43A Hits Mach 7

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  • by Alt_Cognito ( 462081 ) on Sunday March 28, 2004 @10:26AM (#8695338)
    They will need to go back and save the whales etc...
    • by shthd ( 682272 ) <<moc.liamtoh> <ta> <27kluap>> on Sunday March 28, 2004 @12:41PM (#8696015)
      From cnn It is the first time a supersonic-combustion ramjet, or scramjet, which uses air for fuel, had traveled so fast, flight engineer Lawrence Huebner told reporters. The University of Queensland Launched the HYSHOT in July 2002. It Hit Mach 7.6. The first people who did this []
      • by Dan East ( 318230 ) on Sunday March 28, 2004 @02:18PM (#8696512) Journal []:
        As the spent motor and its attached payload falls back to Earth, they gather speed, and the trajectory is designed so that between 35km and 23km, they are travelling at Mach 7.6 []:
        The recent HyShot(TM) launch was designed to take the scramjet engine to a speed of Mach 7.6 (or more than seven times the speed of sound) for the experiment, using a Terrier Orion rocket. The rocket and payload reached an altitude of 314km before the rocket was configured to fly in a new trajectory pointing the payload back down to earth.

        HyShot was simply free-falling to earth in order to reach Mach 7.6 so the engine could be ignited. It achieved that speed regardless of whether or not the scramjet fired. The X-43 was flying horizontally, and was actually powered by the scramjet engine during a controlled flight.

        So there is a difference between what was accomplished. The distinction is that HyShot achieved combustion, while the X-43 was the first scramjet powered craft to be flown.

        Dan East
    • by xs650 ( 741277 )
      The artilce that you linked to said

      "Paul said although signs so far are positive, it still is too early to say the scramjet experiment succeeded. The scramjet experiment took place during the final few seconds of the flight, which lasted almost 10 minutes."

      A quick search with google also did not turn up any reports of confirmed success. Do you have any?
  • sublight speed ;) (Score:5, Interesting)

    by Janek Kozicki ( 722688 ) on Sunday March 28, 2004 @10:26AM (#8695339) Journal
    1 mach = 334 m/s ,
    10 mach = 3340 m/s = 3.3 km/s ,
    speed of light c = 300 000 km/s ,
    (3 km/s)/(300 000 km/s) = 1/100 000 of c

    this engine travelled at aprox 0.00001c !

    good work scientists :)

    • The true question is what is the comparison to the speed of lint? ;-)
    • by ewithrow ( 409712 ) on Sunday March 28, 2004 @10:32AM (#8695372) Homepage

      Of course, rockets launched into space have to travel at least 11.18 km/s to reach escape velocity, which is a lot faster than mach 7. This isnt a speed record, really more of a design change in that the engine doesn't need to carry its own oxygen.

      Congrats to NASA though.
      • by Anonymous Coward on Sunday March 28, 2004 @10:36AM (#8695397)
        I've always been under the impression that escape velocity is if a projectile was fired at ground level, and has no boosting at any later point. Space rockets are continiously accelerated upwards, and thus dont need to reach such speeds.
        • Re:sublight speed ;) (Score:5, Informative)

          by fredrikj ( 629833 ) on Sunday March 28, 2004 @11:02AM (#8695523) Homepage
          Indeed. You need to account for friction, though. Wikipedia article on escape velocity [].
        • Uhm.... no. You are correct in your definition of escape velocity, but orbiting spacecraft reach speeds just about as fast.

          Orbital mechanics tells us that the velocity of an orbiting object is dependent on the mass of the object you're orbiting, and the distance you are from the surface. Thus, when Shuttle is orbiting at 300km altitude, it is traveling at 7.73 km/sec. In order to achieve that orbit, it has to achieve that speed, tangential to the direction of gravity. It can do this (neglecting frictio
          • Re:sublight speed ;) (Score:3, Informative)

            by slim-t ( 578136 )
            Orbital mechanics tells us that the velocity of an orbiting object is dependent on the mass of the object you're orbiting, and the distance you are from the surface.

            I don't have a physics book handy, but I'm pretty sure mass has nothing to do with the velocity.

          • Re:sublight speed ;) (Score:5, Informative)

            by wass ( 72082 ) on Sunday March 28, 2004 @01:34PM (#8696267)
            Orbital mechanics tells us that the velocity of an orbiting object is dependent on the mass of the object you're orbiting, and the distance you are from the surface.

            Not exactly true. When solving the two-body system, a number of coordinate transformations change the equations of motion into a simple one-body equation that can be solved exactly. The mass in the transformed one-body system is called the reduced mass, which is defined as mu=(A*B)/(A+B), where A and B are the masses of the two bodies in question.

            Assuming A>>B (ie, Earth is much greater than the mass of a satellite), this can be rewritten exactly as mu=B/(1+B/A), or w/ a first-order taylor expansion as mu=B-B^2/A. For a standard communications satellite, the second term is approximately 10^-18 times smaller, and can realistically be dropped, and the mass of the satellite is to within measurable uncertainties B.

            But you're wrong in general when you say it's independent of the mass of the object it's orbiting. In the system of the moon orbitting Earth, there's about 1% error by replacing the reduced mass by moon's mass. For a more dramatic example look at a binary star system where one star has 3x the mass of another.

        • by Uber Banker ( 655221 ) on Sunday March 28, 2004 @11:05AM (#8695541)
          Speed is a number and velocity is a vector. So an escape velocity can vary in speed as the angle of escape changes.

          If space rockets are perpendicular (well, they're not really) to the tangent of the atmosphere on exit, their speed still has to be enough to let them escape, but this speed can be really low - I take it implicitly you mean the firing of the rocket is necessary to overcome gravity rather than to reach a certain speed. Conversly, planes in the outer atmosphere can go really fast (speed) but as their velocity does not have a vector pointing upwards they won't exit.

          Acceleration has little to do with it other than making the escape more efficient (of course the rocket changing vector is also acceleration).
          • Re:sublight speed ;) (Score:5, Informative)

            by Maimun ( 631984 ) on Sunday March 28, 2004 @11:33AM (#8695669)
            So an escape velocity can vary in speed as the angle of escape changes.
            Wrong! It absolutely does not matter which direction the velocity vector points to. All that matters is the kinetik energy of the body. The kinetic energy is 1/2 * m * (v^2), where v is scalar, the speed in your terminology.

            See this page [], it is really neat, you can compute escape velocities for different planets.

      • it is a speed record for air breathing engines.
      • Re:sublight speed ;) (Score:5, Informative)

        by SillyNickName4me ( 760022 ) <> on Sunday March 28, 2004 @11:12AM (#8695572) Homepage
        It is a speed record for a vehicle driven by an air breathing engine (ie, it gets its oxygen from the atmosphere)

        Rockets have gone faster, but they carry their own oxygen.
      • Re:sublight speed ;) (Score:3, Interesting)

        by Maimun ( 631984 )
        Escape velocity is necessary only when you want to, well, escape the Earth :)). If you want to go into Earth's orbit, the velocity is 7.8km/s. In fact, this is the minimum velocity you need, given that the direction of the movement is perpendicular to the line that connects you with the center of the Earth, never to fall down. AFAIR, 7.8km/s is that velocity at the Earth's surface. Since there is air friction at the surface, it makes sense to consider that velocity at, say, 250km or more above the surface
    • So officially they can now call them sublight engines.
    • by Nick Driver ( 238034 ) on Sunday March 28, 2004 @11:47AM (#8695744)
      good work scientists :)

      ENGINEERS had more to do with getting this ship up to Mach 7 that did the scientists!
  • Mach 7? (Score:5, Funny)

    by RadRafe ( 632260 ) on Sunday March 28, 2004 @10:26AM (#8695340) Homepage
    Isn't that a shaver? You know, the one with seven blades?
  • by burgburgburg ( 574866 ) <> on Sunday March 28, 2004 @10:27AM (#8695344)
    The engines canna take it, Cap'n.

  • 4 posts... (Score:5, Funny)

    by chimpo13 ( 471212 ) <> on Sunday March 28, 2004 @10:27AM (#8695346) Homepage Journal
    and not a single Speed Racer joke. I'll reload in 30 seconds.
  • Mach10?! (Score:5, Interesting)

    by DigiShaman ( 671371 ) on Sunday March 28, 2004 @10:28AM (#8695351) Homepage
    And just how do you keep something going that fast from burning up in the atmosphere?

    • Re:Mach10?! (Score:2, Interesting)

      by Phosphor3k ( 542747 )
      As a previous poster stated, any vehicles that we launch into orbit need to attain a speed of 11.18 km/s, which is about mach 36, for escape velocity. I imagine they've got more than a few ways to protect this vehicle traveling at a paltry mach 7.
      • Re:Mach10?! (Score:3, Insightful)

        by Phosphor3k ( 542747 )
        Mod me down, I'm an idiot. That speed of 11.18 km/s assumes there will be no further boost during flight, and is the speed of the vehicle right when it leaves the ground. So, the vehicle can go much slower, as long as there is acceleration throughout the flight.
      • where's my mod points?

        "Escape velocity [] is defined to be the minimum velocity an object must have in order to escape the gravitational field of the earth, that is, escape the earth without ever falling back. [...] So, an object which has this velocity at the surface of the earth, will totally escape the earth's gravitational field (ignoring the losses due to the atmosphere.)"

        For the small of brain, the 11 km/s value applies only to unpowered shots (e.g. a cannon) launched from the surface of the earth. Ro
    • Which of course also means less athmosphere for the engine to work with too, but oh well... Given enough speed it might also "leap" out into space where there's hardly any resistance at all, so essentially it'll just come back down to "breathe".

    • Probably because the NASA scientists launching these rockets are smart enough to not attempt Mach 10 at sea level.
    • Re:Mach10?! (Score:2, Informative)

      And just how do you keep something going that fast from burning up in the atmosphere? travelling in the exosphere [].
    • Re:Mach10?! (Score:5, Informative)

      by costas ( 38724 ) on Sunday March 28, 2004 @11:03AM (#8695531) Homepage
      Mach 10 is a record for powered flight; it is not even close to the record of a man-maned craft; IIRC that goes to the Apollo reentry capsules that routinely hit Mach 27 on re-entry. So the heat problem has been solved for quite a while.

      The real problem here is that a scramjet engine is very sensitive to its input (the air coming in) as it only spends literally milliseconds in the combustion chamber. So you have to wonder what aerodynamic tricks the X-43A designers are pulling to smooth that flow before it goes into the intake. Notice the side-view of the aircraft; the belly is smooth and curvy in order to produce many small shocks ahead of the intake and slow down the air as much as possible. A terrific aerodynamic feat, I just have to wonder if it will be reproducible (i.e. stable enought and robust to any aerodynamic event) for a manned aircraft. [Yes, I am an aerodynamicist].
    • Have you not seen the commercials? Don't you know it comes with the Indicator(TM) lubricating strip? It has less irritation... even against the grain!

      Seriously though, someone else said that Mach isn't 757 mph higher in the atmosphere. Considering that, and the known fact that air is thinner at higher altitudes, I don't think you would have as many problems as you think you might... I would be more worried about what happens when the thing hits a pair of migrating European swallows carrying a coconut.
  • The news media keeps reporting NASA's previous failure to reach Mach 5. But didn't the X-15 do this in, like, the 60's?

    And, to keep a little more on topic:
    18 tiems the speed of light!

    • by stripmarkup ( 629598 ) on Sunday March 28, 2004 @10:35AM (#8695384) Homepage
      Yes, they did it in the 60s []. They reached Mach 7 with a manned plane. This one is unmanned. I don't understand why it is such a big deal.
      • by Anonymous Coward on Sunday March 28, 2004 @10:42AM (#8695422)
        Turns out oxygen is heavy, and kind of a pain in the ass to package anyway. It's much more convienent if you can just use the oxygen that's laying about, which is significantly more difficult that it sounds when you're traveling at hypersonic speeds.

        Damn gravity.
        • Unfortunately, the drawbacks of airbreathing appear to outweigh the advantages, at least for vehicles intended to put objects into orbit.

          The problem is that a scramjet trades a dense propellant (LOX) for more of a low density propellant (LH2). As a result, the propellant tanks on a scramjet vehicle would end up being larger (and heavier) than those on an SSTO rocket with similar payload. LH2 is also much more expensive than LOX, so your propellant costs go up (not that propellant cost is currently import
      • by mindstrm ( 20013 ) on Sunday March 28, 2004 @10:50AM (#8695475)
        It's not. This whole experiment is not at all about speed, and everything about a new engine design.

        IIRC, Mach5 is the speed at which the scramjet is released, and ignited... up until then it's just being boosted by a conventional rocket.
        During the first test, the scramjet failed.

        During this test, it worked, pushing the rocket up another mach or two.

        This was not meant to be any kind of speed record.. that's just how fast you need to go to get a scramjet working.
      • It's the engine... (Score:5, Insightful)

        by Kjella ( 173770 ) on Sunday March 28, 2004 @10:54AM (#8695490) Homepage
        Yes, we've done Mach 7 before. And the space shuttles & space probes go much faster. The big deal is the engine. It's like comparing a nuke to some kilotons of TNT. Sure they may have the same effect (Mach 7), but one is simply a gigantic waste of resources (fuel), the other is a valuable invention. And considering it's the military, for good or bad...

      • by the eric conspiracy ( 20178 ) on Sunday March 28, 2004 @11:02AM (#8695528)
        I don't understand why it is such a big deal.

        As some have noted, it's because of the engine type - air-breathing - that makes this so significant.

        The economics of space travel are dominated by the cost to put something in orbit. Sitting on the launch pad, the payload to weight ratio of the Shuttle system is something like 1:50. Picking up the oxygen just lying around gives you a big increment in payload to weight ratio.

    • That was a rocket - this is an air breathing engine.
    • X 15 (Score:5, Informative)

      by p51d007 ( 656414 ) on Sunday March 28, 2004 @10:45AM (#8695438)
      Yeah, Pete Knight went to Mach 6.7 in Oct 67....STILL a record to this day, for a MANNED airplane (X-15 isn't "really" a traditional airplane since it is air launched). Also Pete Knight earned astronaut wings by flying the X15 near 300,000 feet. Several of the X15 pilots received astronaut wings by flying near or over 300,000 feet. Joe Walker, went the highest to 320,000 feet! Sadly, he was killed in the 60's when he was in a formation of planes for an Ad for the general electric engines that all the planes were flying. His "tiny" in comparison jet got too close to the XB-70 bomber (which was suppose to be a Mach 3+ bomber) and it went inverted and smashed into the tail of the bomber, and exploded. Sorry, the early years of test pilots, NASA has always fasinated me, and buddies of mine call me a walking encyclopedia of aircraft knowledge ;)
    • You'll also find the lack of information about the X-15 in things like the Guiness Book of Records. I think this is because the speed the X-15 reached was unverified by an impartial observer, or something like that.

      Another question: Doesn't the space shuttle enter the atmosphere at some crazy mach value like 20? At what point are you defined as being in space, I wonder?

  • Mach 10 (Score:5, Informative)

    by Boss, Pointy Haired ( 537010 ) on Sunday March 28, 2004 @10:30AM (#8695364)
    is 3402 meters per second

    or 12247 kilometers per hour

    or 7610 miles per hour
  • by DoctorPepper ( 92269 ) on Sunday March 28, 2004 @10:31AM (#8695367)
    I can get one of these for my Toyota Corolla? Man, that sure would cut my commute time down!
  • Speed of sound (Score:5, Informative)

    by CaptBubba ( 696284 ) on Sunday March 28, 2004 @10:32AM (#8695374)
    For those of you wondering how to convert between Mach numbers and mph or m/s, here's a nifty java tool [] that lets you see how altitude affects the Mach number.

    basically the higher you go, the less air there is, and the slower sound travels. So, the mach number, which is the ratio of your speed to the speed of sound, will be higher at high altitudes if the speed is constant.

    • Re:Speed of sound (Score:5, Informative)

      by mindstrm ( 20013 ) on Sunday March 28, 2004 @10:47AM (#8695455)
      Common misconception.

      The speed of sound in a gas is affected mainly by temperature... not density or pressure.

      From the page you just linked to:
      "The speed of sound depends on the state of the gas; more specifically, the square root of the temperature of the gas."

      Mach at 35,000 ft is 663mph

      Mach at 150,000 ft is 732mph

      The reason higher aircraft hit higher mach numbers is due to decreased air resistance... concorde can hit mach at 50,000 ft, but not at 20,000.. not because mach is perceptibly slower, but because there is less drag.

    • Re:Speed of sound (Score:5, Informative)

      by Inspector Lopez ( 466767 ) on Sunday March 28, 2004 @11:09AM (#8695561) Journal
      To first order, the speed of sound does not depend upon the pressure at all; rather it depends primarily upon the mean mass density and the temperature.

      The reduction of sound speed at altitude is due to the reduction of temperature. The temperature rises again in the upper stratosphere (ozone heating) and then drops down to its coldest temperature at the mesopause (around 120 K, at 85 km). However, the temperature increases rapidly above that, getting back to room temperature by 110 km, and heading for 1000k and beyond by the time you get to LEO.

      At high altitudes the mass density is decreasing as you get more and more atomic species (e.g. O rather than O2) as well as larger fractions of light constituents (e.g. H2, H), so the speed of sound is quite high at LEO. At altitudes above the "turbopause" (somewhere around 105 km) the components of the atmosphere are no longer well-mixed, thus the different component gases stand at their own scale heights.

      see scale height [] and speed of sound []
  • CNN gets it wrong (Score:5, Informative)

    by AlecC ( 512609 ) <> on Sunday March 28, 2004 @10:36AM (#8695391)
    It also could drastically cut the time of commercial flights -- perhaps shortening the trip between New York and London to less than five hours.

    Considering Concorde did that in three hours, thit wouldn't be much achievement. I make it that it could do NY-LON in just over one hour.

    What I think they should have said is that it could go from any point on the earth to any other, including the antipodes, in less than five hours.

    Mind you, it would take three hours to get through security on departure and an hour on arrival to collect your baggage, if it had arrived with you.

  • Mach 10, projected speed to the end of the year is about 1/3 of the orbital velocity. While already in the same order of magnitude it is still a long way toward the space plane...
  • Great Things to Come (Score:2, Informative)

    by Denix ( 125207 )
    I think this finally points to a replacement for the space shuttle that was sorely needed. The shuttle is a decent space truck, but we need a cheaper (and safer) space "bus."

    Hopefully it will be designed with a space station or dock in mind. It's my understanding that the shuttle was retrofitted for in-space docking such that the International Space Station almost had to be built around it.

    "And how much more black could it be? None more black." - Spinal Tap
  • CNN slipping,... (Score:4, Interesting)

    by epicstruggle ( 311178 ) on Sunday March 28, 2004 @10:40AM (#8695418)
    CNN in a poor programming decision IMHO, did not carry any news of this while it was happening. OTOH FoxNews did!! Which supprised the hell out of me. They did ask some expert a few times how this would mean that missiles (in the future) could hit Osama in 15-30 minutes instead of the 4+hours it takes today. But at least they did have someone talking about the technolodgy/science behind this, and actually showed the takeoff, and launch of the plane. Quite nice of them.

    Kudos to Fox, to CNN: do a better job, or you will fall further behind FoxNews.

    • Re:CNN slipping,... (Score:5, Interesting)

      by dealsites ( 746817 ) on Sunday March 28, 2004 @10:55AM (#8695493) Homepage
      Might be slightly off-topic, but I agree with this. I have enjoyed Fox's coverage much more than CNN's. Not only in this news event but also others. I have noticed that CNN is quite a bit more PC, while FOX news seems to give your the direct information.

      Woot, Woot! Hot Sunday deals are rolling in from all the major deal sites. Slickdeals, Ben Bargains, Techbargain and more! []
      • Re:CNN slipping,... (Score:3, Interesting)

        by bombadillo ( 706765 )
        News is supposed to be "PC". We don't need a TV network telling us what to think. After all how many times last year did Fox news anounce that WMD were found in Iraq?
        • by Jodka ( 520060 ) on Sunday March 28, 2004 @05:47PM (#8697787)
          "News is supposed to be 'PC'"

          The term "Politically Correct" (PC) is a satirical epithet applied to liberal doctrine by conservatives. It mocks the presumption that liberal opinions are the "correct" opinions, in an absolute sense, not one perspective among many.

          The term "PC" is made more amusing to conservatives by the liberals' conviction of their own political correctness preventing liberals from recognizing the joke that liberals' are unawaredly convinced of their own political correctness. "Of course our beliefs are the correct beliefs, why is that funny ?" ask the liberals.

          Which brings us to your assertion that "News is supposed to be PC" What you are telling us ?

          1. That news should be reported from a liberal perspective because...
          2. Liberals are right and conservatives are wrong.
          3. You are blind to the fact that you are promoting your own perspective in absolutist terms.

          Note, "PC" denotes both the status of a particular belief as liberal and the associated presumption of correctness. For example, consider the statement "Johnny failed first grade, but he is African-American, therefore holding him back at that grade level would not be PC". In this sentence, "PC" serves to associate with liberals the principle that unqualified indviduals should be promoted if they are members of a particular ethnic group. But "PC" is also meant to characerize the attitude of those who would defend that principle as an absolutist faith that they are "right" and others are "wrong".

          Fox News is unpopular with liberals not becuase it sets forth alnternative and consertavie "correct" notions, but because it undermines the very notion of correctnees in political discourse. Fox betrays the news broadcast tradition of delivering news in somber, ministerial tones which close off question and doubt; "Though shalt not question the word of Jennings". "The shalt now question the word of Brokaw." The informal on-air attitude of Fox news is like "Here are our correspondents and here is what they seem to to think is going on." It's more upbeat and friendly. We are allowed to ask questions. Fox news conveys to television viewers the dangerous attitude that what you see on TV is people telling you what they think is going on, not sacred and unquestionable truths. It undermines the notion of TV news as a conduit for absolute and correct truths, subverting the entire system of liberal propagandizing through control of unexamined "correct" news content.

          News should not be PC.
    • Yet Fox still managed to blame it not hitting mach 10 on the pink-commie-leftie democrats, and "their heathen ilk"...


  • How fast .. (Score:5, Funny)

    by the eric conspiracy ( 20178 ) on Sunday March 28, 2004 @10:44AM (#8695429)
    new speed record

    African or European?

  • 10 seconds (Score:4, Interesting)

    by henryhbk ( 645948 ) on Sunday March 28, 2004 @10:44AM (#8695430) Homepage
    Did anyone notice that the length of flight was 10 seconds? If it carried enough fuel for a sustained flight, it would be more impressive for a mach 7 flight. I realize this is a proof of concept flight.
    • Re:10 seconds (Score:3, Insightful)

      Proof of concept.

      It worked for 10 seconds. That was all this design is supposed to do, and all it is likely capable of doing, but it proved their combustion chamber design works.

      Now they can strap big fuel tanks on and go for a longer sustained burn, if they want to.
      • I've a sneaking suspicion that it would only work for 10 seconds- 'strapping on a bigger tank' would probably result in it melting. They've probably used heatsink materials to soak up some of the awesome heating effects you get at mach 7.

        Besides, where would they put the bigger tanks? The thing is tiny; and hydrogen is seriously not dense; meaning very little fits into the vehicle.

    • Re:10 seconds (Score:5, Informative)

      by lommer ( 566164 ) on Sunday March 28, 2004 @02:25PM (#8696540)
      In the scramjet reasearch buisiness, 10 seconds is an eternity. Most institutions who are researching this technology are universities and the like who don't have access to B-52s, rocket boosters, and the other equipment needed to actually flight test scramjets. Rather, they are forced to rely on less expensive wind tunnels. To simulate >mach 6 airflow (scramjet operational range), they either use an enourmous piston driven system, or a series of pressure build ups with a simultaneaous release. Regardless of the method, these techniques generally can't provide more than 5 milliseconds of flow time to test the engine. If you compare testing engines in 5 ms bursts to one sustained 10 s flight, the perspective kind of changes your opinion on how long 10 s is.

      If you want a good paper on the subject, I suggest this one [] from the Australian National University.
  • Why its important (Score:5, Informative)

    by Veteran ( 203989 ) on Sunday March 28, 2004 @10:44AM (#8695432)
    SCRAM stands for Supersonic Combustion Ram (jet). What makes this different is that the combustion is taking place in air which is moving faster than the speed of sound inside the engine. Conventional Ram jets require that the air inside the engine be moving at less than sonic velocities for combustion to occur.

    Conventional Ram jets are limited in top speed by the necessity to slow the incoming air down to sub sonic velocities.

    Not only does the SCRAM jet have potential military applications, it can also serve as a 'midrange' stage for a lower cost to orbit booster.
  • by amigoro ( 761348 ) on Sunday March 28, 2004 @10:46AM (#8695449) Homepage Journal
    So what's a Ramjet?

    There's one fundamental difference between an ordinary jet engine and a scram jet engine: The Ramjet has no moving parts.

    The all jet engines,operate according to Newton's Third Law of Motion:
    For every action, there's an equal opposite reaction

    The standard jet engine, invented by Sir Frank Whittle, sucks in air at the front. Then this air is mixed with fuel, and made to combust. The combustion causes the air to exit the engine at a velocity greater than when it came in, thus creating thrust. The escaping air causes the turbine to spin, and this intern activates the compressor, sucking more air in.

    The Ramjet has no turbine and compressor unit. Ramjets fly supersonically and have an inlet which injests subsonic air after it goes through a shock wave in front of the inlet. The intake is slowed down aerodynamically, and then mixed with fuel and made to combust. But after about Mach 5, ramjets don't work so well.

    The scramjet is almost but not quite entirely like a ramjet. The only difference being in a scramjet the combustion takes place as the air is travelling through the chamber at supersonic velocities.

    More [] about the scram jet. Or another [] more concise explanation.

    Moderate this comment
    Negative: Offtopic [] Flamebait [] Troll [] Redundant []
    Positive: Insightful [] Interesting [] Informative [] Funny []

  • by Evanrude ( 21624 ) <> on Sunday March 28, 2004 @10:47AM (#8695457) Homepage Journal
    Then Quantum Leap. Where will Scott Bakula show up next??
  • by Faith_Healer ( 690508 ) on Sunday March 28, 2004 @10:55AM (#8695492) Homepage
    If you want some something that will help understand the scram jet and you have a little aerospace knowledge check out this paper on combustion on a supersonic stream, yslop_hons_thesis_1998.pdf. Its amazeing that this jet can sustain a burn with out a flame holder, at least it looks like it does.
  • by wisebabo ( 638845 ) on Sunday March 28, 2004 @11:05AM (#8695539) Journal
    There's an old Airforce saying:
    A new plane doesn't make a new engine possible: A new engine makes a new plane possible.

    That's why when NASA went for the moon a critical development was the F-1 first stage rocket engine. Capable of 1.5M lbs. of thrust it allowed the Saturn V first stage to be built with only 5 engines. Compare this with the Russian failed manned lunar rocket the N-1 which had 20 engines. They never were able to work all together (vibrational problems) and abandoned it after several launch disasters.

    So why is NASA stopping development? (The successor the X-43C will not be flown). Why are we freezing this enabling technology? Are we (under Bush's program) sacrificing everything to plant a flag on Mars and not making space flight practical? It might be worth it if we ever got to Mars but it looks highly doubtful that his proposal is a serious attempt at anything but votes!

    Sorry for the (mostly) repost but I really wish we would move "faster" towards developing the technologies towards practical* spaceflight.

    *As noted in previous posts, by not carrying the oxygen on board you save a LOT of weight. Remember the reaction is H2 + O = H2O (and energy) and since the atomic weight of oxygen is 16 compared to hydrogen for every kilo of hydrogen you carry you carry EIGHT of oxygen. The weight savings (could be in the millions of pounds) makes up for the turbo-fans/rocket engines you must carry for the takeoff/orbital transition parts of the flight.
    • by demachina ( 71715 ) on Sunday March 28, 2004 @02:13PM (#8696480)
      "So why is NASA stopping development?"

      I'd rather doubt they are. If it can be made to work and there is a need, either the NASA program will be funded or it will disappear in to an Air Force black program and will just appear to have been killed.

      It does appear it can be made to work and it would presumably add a new top end to Aurora or whatever the Air Force's current black program is.

      Its use for civilian transportation is dubious. Its pretty dangerous and would take a LONG time to be made safe, cheap and comfortable. I'm also doubtful it will prove to be a great launch vehicle though you never know.

      Its military applications are obvious. The DOD has a pretty desperate need to drop bombs on targets of interest that arise quickly and move around like Bin Laden. When they get intelligence he is at a place they need to drop ordinance there as quickly as possible before he moves and with some targeting flexibility. A manned or remotely controlled Mach 11 bomber would seem ideal. An RPV version of this could come to fruition a lot faster than a manned version, Cruise missiles, the stealth bomber etc are to slow to get to the target in time. Using ballistic missiles tends to set of alarm bells in Russia, China and everyplace else where governments have satellites watching for launch signatures. Targeting for ballistic missiles also can't be redirected at or stopped at the last minute.

      It would also be priceless for strategic and tactical reconnisance. Spy satellites are to predictable and inflexible since they are locked in to orbits with limited manueverability. Most countries know the schedule and hide stuff when they are overhead. A Scramjet would be flying fast and high enough it would be hard to shoot down, or even detect until after its done the job.

      NASA Dryden deserves a huge pat on the back for finally bending metal and flying something. They've been wasting money on computer generated fantasies for this concept for more than a decade and haven't done much to realize it. It would be fantastic if it lead to a better launch vehicle and civilian transport, I just doubt that it will.
    • The weight savings (could be in the millions of pounds) makes up for the turbo-fans/rocket engines you must carry for the takeoff/orbital transition parts of the flight.

      Actually, the weight savings is non-existent. Sure, you save about 25% of the LOX in your first stage, but that's more than made up by the increased structural weight and thermal protection. Fact is, when the numbers are added up, you frequently come out worse in both weight and cost.

      Using a re-useable airbreathing first 'stage' is a pow

  • Yeah!! (Score:4, Funny)

    by the eric conspiracy ( 20178 ) on Sunday March 28, 2004 @11:08AM (#8695556)

    NASA overclockers RULE!!

  • by Anonymous Coward on Sunday March 28, 2004 @11:44AM (#8695731)
    Let's sum it all up. 1) Escape velocity is IRRELEVANT in the discussion. That applies to unpowered vehicles - not a vehicle under constant power such as this one.

    2) As has been already posted. The speed record isn't for ANY vehicle. The record is for a vehicle with an air breathing engine (ramjet, scramjet, etc). It doesn't apply to vehicles such as the X-15, Apollo capsules, the space shuttles, etc as their speeds were/are either rocket powered or unpowered reentry.

    3) During the first test the scramjet engine did NOT fail. It was never even fired. The booster engine that was supposed to get the scramjet to mach 5 is what failed. If I remember right the fins or something fell off and it went out of control so the remote detonated the booster and consequently the scramjet testbed attached to it.

    4) The toyota corolla attachment won't be out until 2006.
  • by badmonkey ( 29600 ) on Sunday March 28, 2004 @12:12PM (#8695890) Journal
    "The space agency's dogged pursuit of extreme speed, officials hope, will ultimately make space flight easier to accomplish.

    It also could drastically cut the time of commercial flights -- perhaps shortening the trip between New York and London to less than five hours."
    New York to London in less than five hours! That's heresy, that can't [] be done!
  • by jmichaelg ( 148257 ) on Sunday March 28, 2004 @12:14PM (#8695901) Journal
    I'm perplexed by the fact that NASA intentionally threw away the plane before they'd done a post-mortem. The airframe could yield an awful lot of information about how well the craft stood up to the stress and yet they just let it sink in the Pacific. Seems to be either a waste of valuable information or suggests that this is more a publicity stunt than science.
  • by Wingsy ( 761354 ) on Sunday March 28, 2004 @12:37PM (#8695993)
    Looks like the guy who did this reporting for CNN isn't much of a techie. A few things he got wrong: (1) "scramjet, which uses air for fuel" -- quite a few people will read that as not requiring ANY onboard fuel at all. (2) "shortening the trip between New York and London to less than five hours" -- we can already do that in LESS than 5 hrs. (3) "it flew under its own power for six minutes to do maneuvers over the ocean" -- if you count gravity as its own power. It was only powered for 10 seconds under the scamjet, and "glided" the rest of the way to splashdown.

    Now this intrigues me: It was taken to mach 5 by the Pegasus, then it accelerated under the scramjet to mach 7, BUT the engine was only lit for 10 seconds. Does that mean this succer gained nearly 1400mph in 10 seconds???? Wonder what it would do in the quarter? How many Gs is that?
  • by blair1q ( 305137 ) on Sunday March 28, 2004 @01:07PM (#8696139) Journal
    Take a look at the photo of the actual X-43 [].

    All the pics were of the Pegasus booster rocket which was dropped from a B-52. You can't even resolve the X-43 in those photos.

    That X-43 is smaller than most of the bombs that B-52 has dropped in its lifetime.
    • I think the X-43 is 12-feet-long. This quote:

      "The unpiloted 12-foot-long vehicle, part aircraft and part spacecraft, will be dropped from a B-52,aircraft. It will be boosted to nearly 100,000 feet by a rocket..."

      from this [] NASA page is one source.

      I think you are underestimating the size of the Pegasus rocket and B-52 bomber. I know I did. A quick google search found a page on the Pegasus rocket: it is 55.4 feet long and about 4 feet in diameter.

God helps them that themselves. -- Benjamin Franklin, "Poor Richard's Almanac"