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Space Science

NASA's X-43A Vehicle Ready for Flight 57

Posted by michael from the fore! dept.
Aielman writes "NASA has set March 27 as the date for testing the X-43A vehicle over a Navy range in the Pacific. It will be testing a non-rocket air breathing scramjet engine at approximately 5,000 mph. This is the second attempt, the first ending in intentional destruction due to course deviations shortly after launch."
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NASA's X-43A Vehicle Ready for Flight More

NASA's X-43A Vehicle Ready for Flight

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  • How fast would that cross the horizon?

  • I got to wondering what the fastest flight was... (Score:5, Interesting)

    by dukarukus ( 68326 ) on Thursday March 25, 2004 @11:56AM (#8668488)
    (all from guinnessworldrecords.com)

    Fastest Winged Aircraft
    On October 3, 1967, an X-15A-2 piloted by USAF Major William J. "Pete" Knight, was released from its B-52 mother plane at 10,668 m. (35,000 ft.) above the Mojave Desert where it achieved an absolute speed record of Mach 6.7. (4,520 mph)

    Fastest Airliner
    The Tupolev Tu-144, first flown on December 31, 1968, was reported to have reached Mach 2.4, or 2,587 km/h (1,600 mph), but normal cruising speed was Mach 2.2. The Tupolev TU-144, which Nato codenamed 'Charger', was built as a competitor to the British and French Concorde supersonic jetliner, however one of the aircraft crashed during a presentation at the Paris Air Show in 1973.

    Fastest Biplane
    The fastest biplane was the Italian Fiat CR42B. The plane had a 1,100-hp (753-kw) Daimler-Benz DB601A engine, which propelled the craft to speeds of 520 km/h (323 mph) in 1941. Although only a single CR42B prototype was built, 1,780 of the CR42B Falco were produced. It proved invaluable to the Italian Air Force in World War II.

    I realize this last one isn't about speed, i just thought it was cool :)
    Longest Paper Airplane Flight
    The level flight duration record for a hand-launched paper airplane is 27.6 sec., by Ken Blackburn of the USA, at the Georgia Dome, Atlanta, Georgia, USA, on October 8, 1998.
    • I had paper planes flying longer than that when I was a kid and lived in Ukraine. They would get caught in an updraft of a 10-story building and soar really high and take a while to come back to the ground... probably a minute at least.... mine was also probably folded very diffently from an American concept of a paper airplane.

      Then again, this world record is for a level/linear flight. I wonder if he launched it from the top row of the bleachers...
    • It proved invaluable to the Italian Air Force in World War II.

      As I recall, the allies took most of Italy in under 2 months. Unvaluable seems to fit better than invaluable.

      German reinforcements were the only reason the rest of Italy managed to stand as long as it did (though they DID surrender 2 months after the invasion, it was a moot point, as the fighting continued)

      I honestly don't think that it would have been physically possible for the allies to capture the country any faster. The planes certainl

  • BOMARC Ramjet missle (Score:5, Interesting)

    by G4from128k ( 686170 ) on Thursday March 25, 2004 @11:59AM (#8668539)
    The BOMARC [af.mil] was a early ramjet-powered missle from 60s. You can see one in Dayton Ohio at the Wright-Patterson Air Forcebase Museum [af.mil]. One can walk up to the BOMARC and look up inside the ram jets which are nothing more than a hollow tube with a grid of fuel injection nozzles.

  • I don't mean to sound bitter ... (Score:5, Insightful)

    by Daniel Dvorkin ( 106857 ) * on Thursday March 25, 2004 @12:05PM (#8668634) Homepage Journal
    ... but why weren't we doing this 40+ years ago? The X-43 seems to me like a logical evolution of the X-15, which is the kind of thing we should have been working on all this time. Big dumb one-shot boosters to get heavy materials that we never intend to bring back down into space, combined with winged air-launched reusable vehicles for carrying people, instead of hybrids like the Saturn V and the Shuttle ... it seems so obvious, now that we've had decades of a space program which now can't even reliably get people into and out of LEO.

    I'd like to think that we will, in the next decade, see a manned descendant of the X-43 which will use scramjets to achieve orbital velocities and rockets for maneuvering in orbit, and will provide human transportation to/from LEO orders of magnitude cheaper than the Shuttle. It's certainly technically possible. But I'm not holding my breath.

    • Re:I don't mean to sound bitter ... (Score:4, Interesting)

      by WolfWithoutAClause ( 162946 ) on Thursday March 25, 2004 @12:38PM (#8669151) Homepage
      ... but why weren't we doing this 40+ years ago? The X-43 seems to me like a logical evolution of the X-15, which is the kind of thing we should have been working on all this time.

      My question is why anyone is doing this now. AFAIK there's still no useful way on the horizon that a scramjet can help you get to orbit, it's not obviously useful as a way of carrying passengers, it has a *really*, really horrible tendency to melt the vehicle, it maxes out at maybe mach 7.0-9.0 (n.b. orbit is mach twenty five!), the vehicle shape is deeply constrained and the materials to make this concept useful are pretty much beyond the state of the art.

      I mean transportation? Concorde died because it was uneconomic and that ran at 3x lower velocity. Drag is a square law... you do the math.

      Whatever you may think of rockets, they actually do work, whereas, right now, scramjets flat-out don't do anything useful.

      Personally, I think the investment in this technology is missile related. That's the only thing small enough to fit into the shell, and one of the only things that can't leave the atmosphere because their target can't either.

      • Re:I don't mean to sound bitter ... (Score:5, Interesting)

        by Daniel Dvorkin ( 106857 ) * on Thursday March 25, 2004 @12:45PM (#8669253) Homepage Journal
        I was under the impression that they were eventually hoping to get scramjets up to Mach 15 or so -- which isn't orbital velocity, but it's a hell of a lot closer. And you can gain a lot of altitude, too, which makes a difference; the less atmosphere you have to punch through when you light the rocket, the better. Put simply, Mach 15 at 200,000 feet beats 0 at sea level every time.

        I don't have anything against rockets; they do indeed work, and I think we should keep doing everything we can to develop rocket technology in parallel with air-breathing engines. But not having to carry oxidizer for a large portion of the trip to orbit is inarguably a Good Thing.

        • Re:I don't mean to sound bitter ... (Score:5, Interesting)

          by jwriney ( 16598 ) on Thursday March 25, 2004 @01:01PM (#8669480) Homepage
          The touchy bit about airbreathers, though (well, one of them) is the tradeoff between the speed you can gain and frictional heating. Airbreathers won't do you much good if there's no air. But if you get to going too fast where the atmosphere's thick enough to sustain combustion, you quickly get outside the capabilities of existing materials to keep from melting. It's a tricky balance.

          It's cool research, no doubt. But the analyses I've seen seem to indicate that with the added weight of the scramjet itself, and the extra thermal protection you need to run one, it ends up being less efficient then just starting from zero-zero (altitude-speed) and carrying more fuel and oxy.

          --riney
        • I was under the impression that they were eventually hoping to get scramjets up to Mach 15 or so -- which isn't orbital velocity, but it's a hell of a lot closer.

          If they were, it's looking very, very unlikely right now. Getting to mach 10 would be extremely impressive; mach 8.0 may very well be it.

          But not having to carry oxidizer for a large portion of the trip to orbit is inarguably a Good Thing.

          Nope. LOX is dirt cheap, pennies per kilogram; the tanks you store them in are incredibly lightweight; 1-3

        • I was under the impression that they were eventually hoping to get scramjets up to Mach 15 or so -- which isn't orbital velocity, but it's a hell of a lot closer. And you can gain a lot of altitude, too, which makes a difference; the less atmosphere you have to punch through when you light the rocket, the better.

          It's not as close as you might think, in terms of energy, starting at Mach 15 saves you about 5%. But to get that 5%, you end up being heavily constrained by what the aircraft can carry. The sam

          • It's not as close as you might think, in terms of energy, starting at Mach 15 saves you about 5%

            Actually, mach 15 saves you more like 30% energywise, but reaching orbit isn't predominately a n energy thing- it's a speed thing.

            Mach 15 is about 4.5 km/s- that's about halfway to orbit. A relatively modest rocket on top of that would get you the rest of the way provided the scramjet wasn't outrageously heavy (say no more than 20% of the takeoff mass.)

            The trouble is, mach 15 is too much to hope for right no

            • Mach 15 is about 4.5 km/s- that's about halfway to orbit. A relatively modest rocket on top of that would get you the rest of the way provided the scramjet wasn't outrageously heavy (say no more than 20% of the takeoff mass.)

              The problem isn't the scramjet mass, it's the mass needed to get the scramjet up to speed. That's the ultimate problem with airbreathers as first- or zero- stages. The jet that works from zero-zero won't get you anywhere near enough energy to be useful. The jet that can provide enou

              • By the time you make the whole thing 'work', you end up spending a great deal of weight and complexity, and expense...

                Yup. The point is that you gain performance by reducing propellent weight, and by making the system reusable. And yes, of course a reusable system is a priori more expensive. But the amortised cost, if you get the vehicle design right, will be lower.

                • By the time you make the whole thing 'work', you end up spending a great deal of weight and complexity, and expense...

                  Yup. The point is that you gain performance by reducing propellent weight, and by making the system reusable. And yes, of course a reusable system is a priori more expensive. But the amortised cost, if you get the vehicle design right, will be lower.

                  Nope. Because you trade most of that propellant weight for increased structural and system weight. TANSTAAFL.

                  To restate my original, which y

                  • I wouldn't like to bet that an airbreather couldn't work; but most certainly don't.

                    Skylon [reactionengines.co.uk] may be an exception:

                    Basically it uses a precooled jet engine/rocket engine. They believe it would achieve 10:1 thrust:weight and roughly 2000-3000 seconds upto mach 5.

                    The difficult bit is the precooler, but they've done lab tests on one they built and it doesn't ice, and does work (although they mention unspecified 'manufacturing difficulties' which probably means you can't actually build one big enough or someth

        • This is the test of the X-43A, there is also going to be a test of the X-43C which uses a different engine geometry and a hydrocarbon fuel that is supposed to get it up to Mach 15. That's getting close to the holy-grail Mach 24 aka escape velocity. I am sure there is more information here: http://www.nasa.gov/missions/research/x43-main.htm l
      • The motivation is to significantly reduce the amount of oxidizer that has to be carried. LOX is a huge percentage of the launch weight of the shuttle and similar vehicles. If that O2 can be taken from the atmosphere for free - then you might be much better off.

        But, at this stage, it's only "might be". The TPS (thermal protection system) and the need for rocket power for higher altitude (and thus multiple or hybrid engines) start to eat substantially into the weight savings. It's not clear that airbreathers
    • The scram jet might be nice as a secondary state after a conventional propulsion method is used to push the vehicle up to speed and altitude so that the scramjet starts working, but there will need to be a rocket section after that or some self contained drive that does not run off the atmosphere.

      By the time you even get close to LEO, the atmosphere would probably be too thin for the scramjet to sustain itself.

    • Re:I don't mean to sound bitter ... (Score:5, Informative)

      by delibes ( 303485 ) on Thursday March 25, 2004 @01:25PM (#8669817)
      Although ramjets have been around for decades, they've generally been used at speeds of around Mach 1-3. The BOMARC webpage gives a good example, with a speed of just under 2000 mph. Scramjets might one day be developed to work well at around Mach 5-10, but it's been a tricky problem for engineers to solve.

      Scramjet combustion is tricky because the fast air flow can easily blow out the flame. Imagine blowing gently on a small match flame to increase the flame versus blowing strongly on a candle flame to put it out.

      Also the shape of the scramjet generally favours a "sweet-spot" in air pressure (altitude) and speed. This makes them OK for cruise missiles, but not so good for orbital launch rockets. You can try variable geometry (change the shape of the inlet/nozzle) but that means some machinery, which adds weight to the system.

      That brings me onto another problem - thrust/weight ratio. Rocket engines get much higher thrust/weight ratios than air breathing engines. The best air-breathing thrust-weight design that I've seen is Skylon's SABRE [reactionengines.co.uk] (not a ramjet) which will be nice if they can ever build it.
    • 3 Words . . . The Cold War . . .

      Rockets were an easy (ok, relatively easy) and effective way to compete in the space race. Military rockets were already in existance . . . the first US manned space launches were via Redstone Rockets combined with upper stages of Loki rockets (military technology). Why reinvent the wheel during the space race when you can go for incremental improvement on existing technology faster and easier?

      If the USA sat on its hands designing SCRAM/RAM/InsertYourFavoriteSpacecraftPr

    • But I'm not holding my breath.

      good, coz thats my valuable rocket^H^H^H^H^H^Hscramjet fuel you're breathing there buddy!
    • It looks like the X-43 program is going somewhat well in spite of the failure on the first fligh, but I wonder how the X-4000 [uncoveror.com] program is going. NASA doesn't say on their website.

  • Faster than a speeding bullet (Score:5, Interesting)

    by phamlen ( 304054 ) <`phamlen' `at' `mail.com'> on Thursday March 25, 2004 @01:26PM (#8669838) Homepage
    I started wondering about how fast 5000 mph really is. From simple math, thatt's 1.38 miles per second. That is, in fact, faster than the fastest speeding bullet (how fast is a speeding bullet? [hypertextbook.com]) So what could you do with a vehicle that fast?

    Well, my commute (from Brooklyn to Manhattan) takes 35 minutes to go 7.63 miles. I could cut that commute by 34 minutes and 54 seconds. On the other hand, if I didn't mind the commute but wanted to live a little further out from the city, I could live in Los Angeles - my commute to Manhattan would still be just 33 minutes.

    Segway, shmegway! I want a personal scram jet!
    • On the other hand, if I didn't mind the commute but wanted to live a little further out from the city, I could live in Los Angeles - my commute to Manhattan would still be just 33 minutes.

      ... and cost 30x the normal subsonic ticket price from LA to Manhattan. Going at mach many costs mucho. Good luck on paying that every day.

      Atmospheric drag is a square law on speed. The drag has to be overcome by spending fuel unless you plan on leaving the atmosphere, but doing that means the scramjet stops working...

      • WolfWithoutAClause (162946) sez: "Atmospheric drag is a square law on speed. The drag has to be overcome by spending fuel unless you plan on leaving the atmosphere, but doing that means the scramjet stops working... it's all a bit self defeating really."

        Square on speed, reduced by the atmospheric pressure at a given altitude. The operating altitude of the scramjet for this flight is 60 km. That's well above almost all atmosphere. There's only enough for the scramjet due to the high speed.

        "And then there's
        • The operating altitude of the scramjet for this flight is 60 km.

          60km is more than 180,000 ft. The article says 100,000, that's about 30km, which sounds more like it to me. It's my understanding that sonic booms do indeed reach down to the ground from that altitude.

          I'm still quite sure that this vehicle gives a lot more drag. The only way to reduce the drag is to reduce the size, but Concorde is already tiny.

          • "60km is more than 180,000 ft. The article says 100,000, that's about 30km, which sounds more like it to me."

            You're right, my bad. I had the 100km/62.5 mile figure stuck in my head from reading the X-prize docs.

            "It's my understanding that sonic booms do indeed reach down to the ground from that altitude."

            Detectable, probably. Audible, possibly, in a quiet country setting.

            "I'm still quite sure that this vehicle gives a lot more drag. The only way to reduce the drag is to reduce the size, but Concorde is
      • Who says? What's to prevent scramjet/rocket hybrids? We have LOTS of experience with building rockets, we've got that part down. What we don't have is experience operating in the high-mach air regime. By running all these tests, we get closer to the day when all our spacecraft have turbofans to get to mach-speed, and scramjet/rocket hybrids to take us to orbit.
        • Who says? What's to prevent scramjet/rocket hybrids? We have LOTS of experience with building rockets, we've got that part down.

          What I really want to see is a graph or something depicting the ratio of successful and failed rocket launches for each year starting with the first rocket. (Not every rocket ever launched, so lets just say rockets meant to launch into space)

          I just think it'd be interesting to see how far we've come.
      • Going at mach many costs mucho. Good luck on paying that every day.

        sooo .... i guess you're kinda new to the whole 'economy' thing there, eh?

        soon as the technology is -available- and -proven- there will be a massive scramble to implement it ... after all, the atmosphere is abundant with fuel. think of -all- the petrochemical plants we would no longer need to really have in operation in order to maintain our existing jet economies?

        technology, once its figured out and done and demonstrably repeatable un

    • Re:Faster than a speeding bullet (Score:4, Funny)

      by istartedi ( 132515 ) on Thursday March 25, 2004 @06:12PM (#8673902) Journal

      I could cut that commute by 34 minutes and 54 seconds

      If you accelerated to 5000 mph in 3 seconds and then decelerated back to zero in the same ammount of time, you'd cut a lot of other things too... like internal organs and appendages.

    • That's pretty cool, but is it more powerful than a locomotive? Able to leap tall buildings in a single bound?
    • That is, in fact, faster than the fastest speeding bullet (how fast is a speeding bullet?) So what could you do with a vehicle that fast?

      Actually it's not. There is a special projectile/gun type which can reach hypersonic speeds and that is the railgun (no joke). The difference is that the rail gun accelerates in vaccum by electormagnetic means and can easialy reach 5000+ MPh. The US army is experimenting with the thing (which is Huge if large speeds is to be attained) and are planning to build some sort

  • More info (Score:5, Informative)

    by RealErmine ( 621439 ) <commerceNO@SPAMwordhole.net> on Thursday March 25, 2004 @01:33PM (#8669937)
    This link [fas.org] provides some more information on the project.
  • Now, if we can just combine cryogenics with our ramjets, perhaps we can finally make it out of the Slow Zone to the edge of the Lower Beyond...
  • This is the second flight in the X-43A project. On June 2, 2001, the first X-43A vehicle was lost moments after release from the B-52. Following booster ignition, the vehicle deviated from its flight path and was deliberately destroyed. The mishap investigation concluded there was no single contributing factor, but the root cause of the problem was identified as the control system of the booster --NASA

    The first X-43A flight ended in failure June 2, 2001, after the modified Pegasus rocket that carried the
  • I wonder if the military applications for this include manned flight? Imagine shooting through enemy territory so fast, that when you were picked up on radar you were already out of "unfreindly territory." Though how many g's would a pilot endure at 5000mph? And to say the least what of manueverability, could you also imagine touching the stick and moving less than the width of a hair, and spinning endlessly. How would they overcome the problem with an egress system. At that speed as soon as the canopy went
    • how many g's would a pilot endure at 5000mph?
      One, assuming level flight at sea level.
      At altitude, slghtly less.
      Actually, slghtly less than one G at sea level as well, due to the curvature of the Earth (i.e., following the curvature of the Earth means the plane is travelling in a slight arc, producing a slightly negative G force).

    • Though how many g's would a pilot endure at 5000mph?

      G force isn't a function of velocity, it's a function of acceleration (actually, G force is acceleration). In other words, it doesn't matter how fast you're going, it matters how fast you get to that speed. If you're in a car, you'll experience more G force if you go from zero to sixty in five seconds than you will if you go from zero to sixty in fifteen seconds. The same princple applies to flight.

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