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USAF Hypersonic Scramjet Successfully Scrams 201

cold fjord writes "It looks like another milestone for hypersonic flight has been reached. From the story: 'The final flight of the X-51A Waverider test program has accomplished a breakthrough in the development of flight reaching Mach 5.1 over the Pacific Ocean . . ."It was a full mission success," said Charlie Brink, X-51A program manager for the Air Force Research Laboratory Aerospace Systems Directorate. The cruiser traveled over 230 nautical miles in just over six minutes over the Point Mugu Naval Air Warfare Center Sea Range. It was the longest of the four X-51A test flights and the longest air-breathing hypersonic flight ever. . . This was the last of four test vehicles originally conceived when the $300 million technology demonstration program began in 2004. The program objective was to prove the viability of air-breathing, high-speed scramjet propulsion. The X-51A is unique primarily due to its use of a hydrocarbon fuel in its supersonic combustion ramjet, or Scramjet, engine. ... The use of logistically supportable hydrocarbon fuel is widely considered vital for the practical application of hypersonic flight.'"
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USAF Hypersonic Scramjet Successfully Scrams

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  • by a_hanso ( 1891616 ) on Sunday May 05, 2013 @03:16AM (#43633231) Journal

    That's the last of 4 test units built and there's no immediate successor to the program (TFA). Thank god it worked.

    • by AmiMoJo ( 196126 ) *

      Don't worry. China already has hypersonic missiles, and India/Russia are jointly developing one. The US will be forced to develop something comparable, although you might have to wait for the Republicans to get back in.

      • by gtall ( 79522 )

        Wait for the Republicans? Have you listened to Rand Paul or the Svengali of the Republicans, Grover Norquist? These guys are essentially isolationists and figure the U.S. doesn't need much of military because the rest of the world will leave us alone if we leave it for the Chinese to rule.

  • Probably liquid methane, but why didn't they just say it?
  • Next up... (Score:4, Funny)

    by sixshot ( 878181 ) on Sunday May 05, 2013 @03:26AM (#43633247) Homepage

    Ludicrous speed!

  • longest flight.... (Score:5, Informative)

    by WoOS ( 28173 ) on Sunday May 05, 2013 @03:54AM (#43633295)

    A short definition for all those non-native speakers who wonder - like me - how 6 minutes of flight are more than hours of flight by a Concorde:

    Supersonic: Above speed of sound but only up to Mach 5
    Hypersonic: Above Mach 5

    The fact that both the latin Super [] and the greek Hyper [] translate into the same word does not really help the distinction.

    • Supersonic: Above speed of sound but only up to Mach 5
      Hypersonic: Above Mach 5

      The fact that both the latin Super [] and the greek Hyper [] translate into the same word does not really help the distinction.

      Wait. What? I fail to see why two words having the same definition in two languages (Latin/Greek), but different definitions in a third (English), is a problem or is in anyway confusing, unless your endeavor is to speak in all three languages at once.

      • by WoOS ( 28173 )

        but different definitions in a third (English)

        So hyper- and super- mean different things in English? Did the English loosen themselves from the fixation of the Western World of the sacrosanctity of the classical languages and recycled those prefixes into new meanings? Let's check:
        super- []: 1. above, over, or upon; 2. superior in size, quality, number, degree, status, title, or position
        hyper- []: 1. over, above or beyond; 2. excessive
        Hmm, maybe its the ordering ......

        Note that I do understand that supersonic and hypersonic mean different things. That's why I

      • by xaxa ( 988988 )

        The fact that both the latin Super [] and the greek Hyper [] translate into the same word does not really help the distinction.

        Wait. What? I fail to see why two words having the same definition in two languages (Latin/Greek), but different definitions in a third (English), is a problem or is in anyway confusing, unless your endeavor is to speak in all three languages at once.

        We English-speaker hide the meaning of technical words by using Latin or Greek. If you know some Latin or Greek that can often help understand the meaning of English.

        What's "oxygen"? Greek for "acid maker". That corresponds to the German "Sauerstoff", "acid material". Many German technical words are made from normal German words, which helps understanding, IMO.

        "Petroleum" = "rock oil", Greek and Latin. German: "Erdöl" -- earth oil, but Erd and Öl are normal, everyday words.

        (I only speak a littl

    • by drsmithy ( 35869 )

      Is Mach 5 just an arbitrary number, or does something interesting happen at that speed from an aerodynamic perspective ?

      • The air starts to burn the nitrogen with the oxygen giving nitrates; this takes energy and tends to be rather inefficient and changes the aerodynamics.

  • To circle the globe (Score:4, Informative)

    by DKlineburg ( 1074921 ) on Sunday May 05, 2013 @04:14AM (#43633345)
    What is the circumference of the Earth? How far around is the Earth?

    The average radius of the Earth is 3,959 miles (6,374 kilometers).
    The equitorial diameter of the Earth (distance from one side of the Earth to the other at the equator) is about 7,926 miles.

    The ratio of the circumference to the diameter of a circle (circumference/diameter)
    is written as the symbol pi.
    Pi is approximately 3.141592.

    Therefore, to determine the circumference from the diameter given above:
    equitorial diameter x 3.141592 = equitorial circumference
    | |
    7,926 x 3.141592 = 24,900
    | |
    The earth has a circumference of approximately 24,900 miles.

    More precisely the circumference of the earth
    at the equator is 24,902 mi / 40,076 km.


    5.1Mach = 1.7355km/s
    Source: []

    It depends on what type of plane you are flying in and what air routes you plan to take. The typical duration is usually 2 days to 4 days.

    For instance, an F-16 could theoretically circumspect the world in slightly less than 78 hours. But that's only possible if all the refuellings are conducted as in-flight refuellings, via airborne tankers. With luck and some good currents around, it might shave 2 hrs or so off the total time needed. But then again, unless you can stay awake for 3 days without sleep, its damn near impossible to do that.

    For a civilian airliner like a Boeing 747 or an Airbus, it would take around the same amount of time, largely due to the need to bring it down to an airstrip for refuelling. But because of its huge internal fuel capacity, it could remain airborne far longer than an F-16.

    To help you with your essay, I'm going to list the conditions required to accomplish this in a realistic manner:

    1) Type of aircraft and its configuration
    A civilian airliner jet (like those 2 mention earlier) typically have intercontinental ranges in excess of 3,000km. Also, they are capable of carrying huge quantities of internal fuel. Assuming you take a Boeing 747, removed all the seats in the passenger compartment and turn them, along with the cargo area into fuel storage, that range will be increased dramatically, from 3,000km to 7,000km.

    Taking it further, by adding a refuelling receptor to the jet itself, similar to those used by the Air Force for its planes like the C-17 Globemaster III, the maximum range effectively becomes unlimited.

    2) The human factor
    Flight operations are no trivial task. While computers and automated intelligent system have made it easier for modern day pilots, the task of flying itself is still a tiring activity. Pilots need to maintain vigilance not only over the flight systems on the aircraft but also need to keep an eye out for weather conditions. Although the availability of long range radar and weather satellites have made detection of distance storms easier and earlier, its ultimately a human that takes actions to avoid it.

    Maintaining wakefulness is a mentally exhausting affair, especially when is also an extremely dull affair, since an un-occupied mind is a bored mind, which translate into mental lethargy, which is also sleepiness. A human being usually loses his ability to react quickly after 12 hours of continuous flying. After 18 hours, that ability falls by 10% for every 2 hours after that.

    3) Flight profile and weather conditions
    The reason why airliner jets can sustain long range flights is because it cruises along at high altitudes. This is one of the aspects of aerodynamics, the higher you fly, the less fuel you burn, thus allow maximum milage per pound of fuel.

    Air currents can aid and also hinders an aircraft's performance. With the proper air currents available (dependant on the time of
  • Applications? (Score:5, Informative)

    by KonoWatakushi ( 910213 ) on Sunday May 05, 2013 @04:38AM (#43633373)

    A fascinating development, but I worry that the applications are limited to delivering bombs. Since the engine doesn't even function below hypersonic speeds, a plane and rocket are necessary to even launch them, and that naturally limits the size. As such, I don't particularly see the development as a positive thing in the near term, nor does it make me feel any better that the US military is the one doing it.

    A hybrid jet/rocket engine like the SABRE [] is far more attractive, as it can deliver Skylon [] from runway to space, and is efficient throughout. The remarkable enabling technology is a precooler which cools incoming air from 1000C to -150C in milliseconds, and has already been successfully demonstrated.

    Furthermore, there is a also a variant optimized for atmospheric flight called Scimitar [], which uses the precooler with a high-bypass turbofan engine, giving it good efficiency and subsonic exhaust velocities at low speeds. This flexibility and broad efficiency allow the A2 [] to operate over land as well, overcoming the limitations of the Concorde. It has the potential to make commercial hypersonic flight ubiquitous.

    • Theoretical (Score:5, Insightful)

      by dutchwhizzman ( 817898 ) on Sunday May 05, 2013 @05:29AM (#43633465)
      The whole Sabre engine is still conceptual and not one working engine has flown anywhere. Also, the SABRE relies totally on liquid helium to cool air and can't use any other gas. Since Helium supplies are very limited and the price is kept artificially low, no large commercial flight will ever be possible with this technology.
      • by KonoWatakushi ( 910213 ) on Sunday May 05, 2013 @07:05AM (#43633661)

        SABRE is a sound concept which combines proven technologies in a new way, enabled by the novel heat exchanger. Not only has the heat exchanger has been demonstrated, the ESA has thoroughly examined the concept and finds no fault with the engine. The helium (which is not liquid by the way) is not consumed, nor are prohibitively large quantities required.

        By your reasoning, there would never be any innovation at all, and we would live in a technologically static world. I do not understand the compulsion of people to endlessly and vehemently complain about the impossibility of perfectly sound concepts. Progress still happens, though probably at a considerably reduced rate thanks to this prevailing mindset.

        Seriously, what is with the total lack of vision these days? Why is it that everything that can't already be purchased, is considered to be impossible? If not a sound concept with demonstrated components, what, if anything, will convince people to support innovation? I'm genuinely curious, as this seems to be holding up other critically important innovations such as molten salt reactors.

        • I do not understand the compulsion of people to endlessly and vehemently complain about the impossibility of perfectly sound concepts

          Maybe try talking to the guy who says the following []

          Tokamak fusion is not, and will never produce economical power, even if it works

          (emphasis mine) Maybe he can explain it to you.

          Maybe you'll claim that it's not a sound concept, but there are quite a few experimental reactors that exist now.

          I like SABRE, I also like Tokamak. Will either one actually succeed? I don't kn

          • I considered including an explanation to head off this inevitable response, but thought it was off topic. The reason is not a matter of technological advancement, but of the fundamental physics of the tokamak. When the physics makes something impossible, I occasionally resort to the term "never".

            The tokamak has to be enormous for it to work, and that has a direct impact on the economics. Even today, for 1GW fission reactors, financing is difficult, and they are nowhere near as complex. Beyond the prohib

      • They've tested it at the test rig and it works fine.

        The engine has a far easier time than scramjet engines, they should be able to keep the running for hours; good luck with getting a scramjet engine to do that!

        SABRE idea has also got a huge advantage that the cycle works with excellent thrust and efficiency from zero speed all the way up to Mach 5.5. Scramjets ONLY work above Mach 4 or so.

      • by EdZ ( 755139 )
        The Intercooler operates on a Helium loop, but the loop is closed: it is the Hydrogen fuel that provides the cooling, and no Helium is lost in operation. Additionally, the Intercooler, the hardest part of the engine, has been tested successfully. The rest is running turbines and a rocket on H2, which has been done numerous times in the past.

        The big barrier is that it doesn't scale down well at all: you can't built a small vehicle that you can actually use for launching anything, you have to stump up the
    • I'm pretty sure Ray Stalker saw it as a second stage to orbit when he came up with the idea. Having to carry less fuel is a very major consideration in such a situation.
      I would like to point out however that you are writing about those theoretical designs as if a test model exists but it is not the case, while scramjet models have been performing in tests since the 1980s. It's a bit misleading to write as if the engine exists when only the precooler has been tested. They may be the way of the future but
    • Funny thing is this technology is never going to deliver anything (not even bombs) that a 20 year old ICBM wouldn't do faster, cheaper and easier. The only reason the USAF wants it is because firing ICBMs tends to get the Russians (and Chinese) a little jumpy. What everybody very hard does his best to ignore, is that the scramjet obviously also could deliver nuclear warheads, which means the foreign siblings of NORAD should be hard at work learning to detect these things. By the time this technology is o
    • Sure, SABRE sounds great, in the exact same sense that fusion sounds better than fission-based nuclear power.

      Of course, like that comparison, scramjets are a relatively simpler technology that's already been conceptually proven, while the hybrid engine you're talking about is - despite the proof of concept for the cooling function - largely vapour.

      And, by the way, the hybrid engine programme WAS originally a military concept development, but was set aside for other more promising developments. To fear that

      • Your analogy doesn't work, as SABRE is actually a sound concept, with well understood physics. It is an involved, but tractable engineering problem. Tokamak fusion is not, and will never produce economical power, even if it works. Nor are most other fusion options attractive when compared to the simplicity and economics possible with molten salt fission reactors. (The exception being aneutronic pB11 fusion in a Polywell, DPF, or such, but those are a much harder nut to crack, if they are even possible.)

        • You're saying that SABRE works well in theory, then you say that scramjets, despite working well in theory, are much more difficult in practice. This doesn't make SABRE a better design. It just means that SABRE's engineering difficulties have not yet been demonstrated by actually flying.
          • You didn't bother to read those sections I mentioned, did you? Nowhere did I say that scramjets work well in theory, quite the opposite. Why would you pursue something that doesn't work well even in theory, at such great cost? What makes SABRE a better design is a sound concept offering greater potential efficiency across the spectrum, and general usefulness.

            Cooling the incoming air has very real advantages in the thermodynamic cycle as well relaxing requirements for materials.

  • Fuel (Score:4, Funny)

    by Konster ( 252488 ) on Sunday May 05, 2013 @04:41AM (#43633383)

    For those of you who asked what fuel it uses:


    Top Secret.

  • by Lincolnshire Poacher ( 1205798 ) on Sunday May 05, 2013 @06:04AM (#43633523)

    Ease off the hyperbole.

    1991: The first recorded successful scramjet test, when a modified Russian SAM was used as a booster for an engine which achieved supersonic combustion for 5 seconds.

    1992: Another similar test, with French funding, pushed that out to 15 seconds.

    2002: HySHot demonstrated the first controlled flight with supersonic combustion ...

    2013: A milestone! A breakthrough!

    • by EdZ ( 755139 ) on Sunday May 05, 2013 @08:07AM (#43633833)
      Running on something other than H2 outside the lab is a breakthrough You can't rely on your cryogenic fuel to cool your engine, you need to build a chamber that will handle massive shockwaves at hilarious temperatures.
    • by Moofie ( 22272 )

      I think this latest X-51 flight may have been longer than the sum of hypersonic burns on all tests thus far, but I may have overlooked some of the more recent ones.

      Suffice it to say, a several-minute burn, with acceleration, is not a trivial accomplishment.

      So what's your beef?

    • I was in school when the Russians did it, and that was nice and unique because it happened in flight. Except that they had to accelerate to beyond M5 before they turned it on because the net thrust was effectively negative (it slowed down quickly as soon as the SCRAMjet was fired). It buried itself in the Siberian tundra (as planned) as part of a simple ballistic trajectory.

      Even the HyShot was not designed to produce actual thrust.

      The Waverider produced net positive thrust, accelerating the vehicle from Mac

  • Now we have another, faster way to deliver death to people we don't like.

As of next Tuesday, C will be flushed in favor of COBOL. Please update your programs.