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NASA's X-43A Vehicle Ready for Flight

Posted by michael on 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."

13 of 57 comments (clear)

  1. I got to wondering what the fastest flight was... by dukarukus · · Score: 5, Interesting

    (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.

  2. BOMARC Ramjet missle by G4from128k · · Score: 4, Interesting

    The BOMARC was a early ramjet-powered missle from 60s. You can see one in Dayton Ohio at the Wright-Patterson Air Forcebase Museum. 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.

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    Two wrongs don't make a right, but three lefts do.
  3. I don't mean to sound bitter ... by Daniel+Dvorkin · · Score: 5, Insightful

    ... 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.

    --
    The correlation between ignorance of statistics and using "correlation is not causation" as an argument is close to 1.
    1. Re:I don't mean to sound bitter ... by WolfWithoutAClause · · Score: 3, Interesting
      ... 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.

      --

      -WolfWithoutAClause

      "Gravity is only a theory, not a fact!"
    2. Re:I don't mean to sound bitter ... by Daniel+Dvorkin · · Score: 4, Interesting

      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.

      --
      The correlation between ignorance of statistics and using "correlation is not causation" as an argument is close to 1.
    3. Re:I don't mean to sound bitter ... by jwriney · · Score: 4, Interesting

      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

    4. Re:I don't mean to sound bitter ... by delibes · · Score: 5, Informative

      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 (not a ramjet) which will be nice if they can ever build it.

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      This is not a sig
    5. Re:I don't mean to sound bitter ... by DerekLyons · · Score: 2, Interesting
      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 same goes for altitude, a rocket actually spends very little of it's fuel gaining altitude, the bulk of it goes to gaining horizontal velocity. (Without horizontal velocity, you don't get orbit.) Again, you get a slight gain, but at a great cost.
      Put simply, Mach 15 at 200,000 feet beats 0 at sea level every time.
      Put simply, that's what commonsense would seem to dictate. But in reality, the numbers don't add up. It turns out that to launch a Soyuz sized payload, you need an aircraft larger than any ever seriously contemplated. (Think something the equivalent of six to eight C5A Galaxies. Imagine how much it will cost to develop and support such a beast.) In the end, an airbreathing and recoverable first stage turns out to be uneconomical as hell.
      But not having to carry oxidizer for a large portion of the trip to orbit is inarguably a Good Thing.
      It would be - if airbreathers could do that. But in the end, they best they can do is a very small fraction of the trip.
  4. Faster than a speeding bullet by phamlen · · Score: 4, Interesting

    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?) 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!

    1. Re:Faster than a speeding bullet by WolfWithoutAClause · · Score: 2, Insightful
      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... it's all a bit self defeating really.

      And then there's the slight problem of a sonic boom- didn't you learn anything from the commercial failure of Concorde? And that only went at mach 2.2.

      --

      -WolfWithoutAClause

      "Gravity is only a theory, not a fact!"
    2. Re:Faster than a speeding bullet by istartedi · · Score: 3, Funny

      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.

      --
      For all intensive purposes, "whom" is no longer a word. That begs the question, "who cares"?
    3. Re:Faster than a speeding bullet by Yazeran · · Score: 2, Informative

      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 of tank killer using just the kinetic kill principle.

      For reference look Here or here

      Yours Yazeran

      Plan: To go to Mars one day with a hammer.

  5. More info by RealErmine · · Score: 4, Informative

    This link provides some more information on the project.

    --
    Dewey, you fool! Your decimal system has played right into my hands!