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Science Technology

HyShot Scramjet Test Declared a Success 253

Posted by michael from the once-the-scramjets-go-up dept.
An anonymous reader writes: "ABC news is reporting that analysis of the flight data from the recent HyShot scramjet test (covered by Slashdot previously) suggests that the test was successful and that the engine achieved combustion in flight after reaching Mach 7.6. The University of Queensland is also reporting the news."
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HyShot Scramjet Test Declared a Success More

HyShot Scramjet Test Declared a Success

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  • BBC link on the story... (Score:5, Informative)

    by MrFenty ( 579353 ) on Friday August 16, 2002 @08:28AM (#4082061)
    BBC story [bbc.co.uk]

  • Mach 7.6 !! (Score:3, Funny)

    by af_robot ( 553885 ) on Friday August 16, 2002 @08:32AM (#4082086)
    Wow!
    This must be twice better than Gillete Mach3 system !!

    • Re:Mach 7.6 !! (Score:4, Funny)

      by yeoua ( 86835 ) on Friday August 16, 2002 @08:45AM (#4082147)
      Depends on what you think is better. The Gillete Mach3 system will take 3 swipes at your hair. This Scramjet system seems to attempt to take a record 7.6 swipes at your hair. Not sure how they do the .6 of a blade though... but from the commercials, the 3rd blade seems to essentially get as close to the skin as possible. So then the 4th blade must then (in a logical progression) take of the top layer of skin. The 5th blade then takes out the middle layer of skin. The 6th blade takes out the lower layer of skin. This is a highly good design as if you shave really fast, by the time it hits the 6th blade you should have shaved off all your nerves so it shouldn't even hurt anymore.

      Which leaves the 7th blade to shave off some bone, to polish it maybe. Now that .6 of a blade that is left... maybe its some new encryption scheme for their razor so no one can exactly copy their design, as who would want to make .6 of a blade? Perhaps it means its only 60% as sharp as the rest of the blade and used to buff your bone?

      Well then, this has to be the closest shave you'll get, and with your skin gone, you should have no growth after, as the bulbs should have been rooted with that skin by then.

  • Photos, other links, and more (Score:5, Informative)

    by danish ( 60748 ) <danish@debian.org> on Friday August 16, 2002 @08:39AM (#4082109) Homepage

    There's a ton of photos at http://photos.cc.uq.edu.au/HYSHOT/ [uq.edu.au] and also at http://www.mech.uq.edu.au/hyper/hyshot/HyShot_phot os.html [uq.edu.au]. The former link has some friggin huge jpegs.

    There is also a page about the HyShot program itself at http://www.mech.uq.edu.au/hyper/hyshot/ [uq.edu.au]

  • Mach speeds (Score:2, Interesting)

    by andyring ( 100627 )
    The thing I don't like about Mach numbers is it's not consistent. Reason being, the speed of sound changes based on your altitude. Higher, where the air is thinner, sound travels slower. So Mach 7.6 at 50,000 feet is a lot slower than Mach 7.6 at sea level. Sure, it's a cool sounding number, but I wish we'd see these numbers represented in miles or kilometers per hour as well as a Mach speed. When the author of the article gave the comparison of a London-Sydney flight, (2 hours vs. 20), was he/she figuring that based on Mach 7.6 at sea level or at 75,000 feet? (not to metion it'll be decades before, if ever, we see passenger planes anywhere near this speed)

    • Re:Mach speeds (Score:5, Informative)

      by jamie ( 78724 ) <jamie@slashdot.org> on Friday August 16, 2002 @08:49AM (#4082168) Journal
      "The thing I don't like about Mach numbers is it's not consistent. Reason being, the speed of sound changes based on your altitude. Higher, where the air is thinner, sound travels slower."

      Untrue. Sound travels slower because the air is colder, not thinner. The speed of sound in the Earth's atmosphere is proportional to the square root of the temperature, nothing else. http://www.allstar.fiu.edu/aero/mach.htm [fiu.edu]

      Here's an atmosphere simulator [nasa.gov] where you can pick an altitude and see the speed of sound. As it says, "the speed of sound depends on the temperature and the gas," not on pressure.

      • Re:Mach speeds (Score:3, Interesting)

        by jshine ( 321403 )
        Well, that's kinda deceptive really, because pressure and temperature are very related for a gas. If you model the gas as idea, then you get the relationship:

        P*v=R*T (where v=V/N) or, if you'd rather use density...

        density (rho) = P*M/(R*T)

        So, you can have temperature in terms of pressure, or pressure in terms of temperature. They are interrelated: with a gas, you can't change one of those parameters in isolation.
        • This is true in a closed system, without heat addition. This is not the atmosphere. In the atmosphere the Pressure dropps off logarithmically, but the temperature makes a kind of sinusoid.
        • Actually, I feel you're the one being deceptive.

          The temperature is given in terms of pressure AND volume, or density and pressure. For any given temperature you can have any pressure at all by varying the volume. THERE IS NO DIRECT RELATIONSHIP BETWEEN PRESSURE AND TEMPERATURE.

          The volume of the atmosphere can and does vary.

      • Re:Mach speeds (Score:2, Insightful)

        by Marx_Mrvelous ( 532372 )
        His statement is entirely true; as altitude increases, the air does indeed grow thinner, and the speed of sound indeed decreases. And the sped of sound is definitely linked to density, which is why it travels so much faster in water than in air (even at the same temperature).
        • Exactly. I think the difference between pressure and density is causing confusion.
          • No, actually you can work it out. The speed of sound in a gas in meters per second is equal to sqrt(ratio_of_specific_heats*8.314*Temperature/mas s_of_one_mole_in_kg)
            The only pressure dependance is a very small one, through the ratio of specific heats. Basically the speed of sound in a gas is independant of pressure and density.
            • Blockquoth the poster:

              Basically the speed of sound in a gas is independant of pressure and density.

              IANAAE (I am Not an Aeronautical Engineer), but isn't this due to the assumption of ideal behavior? In Physics, you learn that the speed of sound is proportional to sqrt(dP/dD), ie., dependent on the derivative of pressure with respect to density. This makes actual physical sense, as it connects the restoring force (via the pressure) to the inertia of the gas (via the density).


              In an ideal gas, P = DRT, so dP/dD = RT. And hence the dependance on temperature and the apparent independence from P and D.

              • .. but why do they always say "at sea level" when qualifying the speed of sound?
                • Blockquoth the poster:
                  .. but why do they always say "at sea level" when qualifying the speed of sound?

                  Because properties of the atmosphere vary remarkably with height. You need a reference point, and by amazing coincidence :) "sea level" is where the majority of experiments are done (more or less -- we're talking about variations in height for the airplane that are much greater than the variation in altitude of fixed installations).
                  • ... so being that those properties are a secondary effect compared to temperature, why is "at sea level" stressed more than "at X degrees C", or is that just my perception?
                    • Blockquoth the poster:
                      ... so being that those properties are a secondary effect compared to temperature, why is "at sea level" stressed more than "at X degrees C", or is that just my perception?

                      IANAAE, but my assumption is this: Above the troposphere, the temperature is actually pretty close to a function of height. On the other hand, a lot of this data was probably amassed by weather balloon, and there's a good reason -- which I misremember -- as to why the pressure data is used as the yardstick. I think the boundaries between layers varies somewhat with time, but I'm not sure.


                      Actual answer: It's probably just habit and social inertia.

      • Actually for Hyshot, the design temperature was 220 Kelvin. A weather balloon was sent up beforehand, to make sure that the air wasn't so cold as to suppress combustion.

        The Mach number is a similarity parameter. That is, all craft travelling at Mach 7.6 experience similar problems, regardless of the actual speed. Other similarity parameters include the Prandtl, Reynolds, Stanton and Damköhler numbers.

      • Re:Mach speeds (Score:2, Interesting)

        by grgyle ( 538200 )
        "Untrue. Sound travels slower because the air is colder, not thinner.." No. First off (for qualification's sake), I have degrees in Physics and Astronomy and work professionally as an engineer. You are misunderstanding the pressure/volume/temperature relationships of the gas laws (freshman physics material). One can express mach number in terms of a pressure dependency, a temperature dependency, or a density dependency. For an ideal gas, the parameters are interrelated. Go back and really read the equations on the web page you quoted. It is equally as true to say mach is density dependent as it is to say it is temperature dependent for a given gas.
    • Mach is an accepted measurement of speed, and when used as such it does indeed have a specific value [fiu.edu]. Reference Mach is measured at 15 deg. Celsius at sea level, yielding ~340 m/s or 1224 km/h (someone feel free to doublecheck the math, conversion and multiplication errors abound when you post).

      So while, yes, the speed of sound does indeed change with altitude (due to temperature changes, which is related to pressure changes), the reference Mach value does not. So Mach 7.6 was 9306 km/h or 5784 mph.
  • While scramjets raise the possibility of Sydney to London flights in two hours, they are set to revolutionise the launch of small space payloads, such as communications satellites, by substantially lowering costs. They have the added benefit that they do not even have to carry most of their propellant as they use oxygen from the atmosphere.

    Just wondering, but wouldn't travelling at Mach 7.6 be a little tough on a human? I'm no physisct, but it seems like the G's would be something really painful for a human. Of course, maybe the two hour flight from London to Sydney wouldn't require Mach 7.6 speeds.
    • It's only a high rate of acceleration that causes passengers to experience excessive G force. Once you've reached Mach 7, so long as you remain at a constant velocity nobody should notice how fast you're going.

    • Re:Mach 7.6- isn't that a little tough for travell (Score:4, Funny)

      by GypC ( 7592 ) on Friday August 16, 2002 @08:53AM (#4082194) Homepage Journal

      G-force is created by acceleration, not speed. Otherwise the speed of Earth's orbit around the sun would crush us all.

      Nonetheless, I'd rather be in Sydney in 2 hours with a bloody nose and bruised ribs than endure a 20 hour flight with a bunch of Englishmen...

    • I've been wondering that myself, and have been trying to find info on the limits of the human body (with no luck yet).

      At best, it would probably be uncomfortable, and that would make it unsuitable for commercial flights.

      It's the same reason we don't have flying wings for commercial flights - many of the passengers would be made uncomfortable during turns.
    • Assuming you weren't trolling:

      Mach 7.6 is a speed, not an acceleration. A hypersonic passenger vehicle will presumably travel with moderate acceleration until reaching high speed.

      At 1/2-earth-gravity acceleration, you get one sea-level Mach number per minute, more or less, so you'll be at Mach 7.6 a few minutes after launch.
    • Just wondering, but wouldn't travelling at Mach 7.6 be a little tough on a human? I'm no physisct, but it seems like the G's would be something really painful for a human.

      Mach is a measure of speed relative to the speed of sound at a given elevation, it is not a measure of acceleration. So, at sea level, Mach 7.6 is roughly 5800mph (~2600m/s), but at 25000ft, where the air is thinner, Mach 7.6 is about 5000mph (~2250m/s).

      The gravitation of earth (ie, the amount of force we feel from gravity) is 9.8m/s^2. So, a constant 1G force (which the body won't find too uncomfortable) would accellerate a body to 2250m/s in about four minutes... If a genter push is desired, say .5G, that level of acceleration would need to be maintained for a bit over seven and a half minutes...

      Unless, of course, my physics is rusty.. :^)

  • other applications? (Score:3, Interesting)

    by Alien54 ( 180860 ) on Friday August 16, 2002 @08:57AM (#4082223) Journal
    Some how I can imagine the military trying to figure out how to make this cheaply enough to use in something like an upgraded version of the Tomahawk Missile. (which currently run at about 600mph or so)

    Something like that would be impressive, and also would have definite mind bending impact on the popation below, just due to the sonic boom.

    • Scramjets are not the ideal engine for missiles. Amongst other things, the whole front of the engine is required for the air intake, which doesn't leave much room for a guidance package. The next is that the nose of the missile itself would be hot, complicating any heat seeking guidance. the last is a practical issue. Solid rockets are incredibly reliable, and it would take a lot to trade reliability for a possible increase in range.
    • There are already supersonic cruise missiles and anti-ship and anti-air missiles. Russia especially has invested alot of capital into this area of weapons research.

      They aren't scramjets, but Mach 2.5 - Mac 5 ain't nothin to laugh at, either. ;)

  • Just one problem... speedbumps (Score:3, Interesting)

    by Dark Nexus ( 172808 ) on Friday August 16, 2002 @09:02AM (#4082250)
    Ever hit a speedbump at low speeds?

    Not that bad.

    Ever hit one at a higher speed? Say, at least twice it's rating (hitting a 15km/h bump at 30km/h, for example)?

    It's not the most pleasant things.

    Now, you're saying that "Planes don't have to worry about speed bumps!", and you're right.

    But what about turbulence?

    You can hit turbulence at Mach 0.76 that's pretty rough. What would that same turbulence to do a large plane at Mach 7.6?
    • One of the interesting footnotes from aviation is the first attempt at breaking the sound barrier. As you approach the speed of sound turbulence increases dramatically. However, when you break it you are in a new aerodynamic regime and suddenly the turbulence plummets. A very pleasant surprise to Chuck Yeager, the first supersonic pilot.

      You can find more information about the "Wall of Air" that was believed to prevent supersonic flight, as well as Yeager's breaking on the barrier here:

      http://www.capstonestudio.com/supersonic/main.ht ml
    • You can hit turbulence at Mach 0.76 that's pretty rough. What would that same turbulence to do a large plane at Mach 7.6?

      Planes fly Mach 0.76 at 30000ft. A plane flying Mach 7.6 would be much higher, upwards of 100000ft, where there is very little air to cause turbulence. Friction becomes an issue. When the X-15 [af.mil] flew Mach 6,

      Air friction at speeds much above Mach 6.0 would weaken even the X-15's chrome-nickel Iconel X skin, so a special resin-and-glass-bead ablative coating was developed that would gradually sear away in flight, carrying with it the excess heat.
      Let's hope they get that problem worked out...
    • Well that depends on how turbulance works when you that supersonic

  • This is a really cool idea and I'm glad it's beginning to pan out. If the global scientific community wants to continue to move forward during this century as rapidly as it did during the last, it needs to tackle problems with innovations like these instead of simply trying to ameliorate other people's ideas.

    For instance, a friend of mine thinks that the future of the computer industry lies in abandonning the binary basis that has been established and beginning to work with, perhaps, a 4-state diode... Granted, it's not exactly the best idea, but a good example to illustrate my point: it's only a matter of time before old ideas get stale. How many of us have even considered Base n != 2 computing?

  • I dig the tech ... but from preceding comments I believe that a somewhat false impression has been made on a few people: There is indeed this fantastic engine which can reasonably efficiently propel you around the globe at speeds exceeding that of sound by a factor greater than the number of finger most people have on one hand - but: it has to be accelerated to more than twice the speed of the fastest jet aircraft built to date [wvi.com] for it even to ignite.

    I once had this motorbike I always had to push start. It was quite annoying.

  • HyShot Scramjet Test (Score:4, Informative)

    by sagavia ( 211718 ) on Friday August 16, 2002 @10:04AM (#4082608)
    As I read the comments, it seems that some people don't get the implications. In a normal jet engine the flow has to be slowed to less than Mach 1 for compustion to occur. Faster, and it goes out. This limits the range of velocity that can be attained. So, there is a range of velocity that can only be attained with rockets. With a working Scramjet it becomes possible to fly most of the way to orbit. From an energy consideration, once you are in low earth orbit you are half way to anywhere in the solar system and can use low acceleration, high efficency engines to get anywhere.

    Scramjets are the realistic key to space exploration.
    • Ok, Einstein, you've got the basic theory. Now explain:

      a) the difference between mach 7.6 and mach 25

      b) how you stop the thing melting at mach 10-20

      c) why the term 'dry mass' is rather important to something that wants to achieve orbit and compare and contrast the thrust/mass ratio of a scramjet with a rocket engine

      d) how you accelerate up to the minimum speed this engine needs to begin to work (hint: it's called a "rocket", or a jet engine (see point c))

      e) how drag ultimately limits how long you can spend in the atmosphere (hint: drag goes as a square law with velocity, but oxidiser input from the air only goes linearly).

      In a normal jet engine the flow has to be slowed to less than Mach 1 for compustion to occur. Faster, and it goes out.

      Actually I thought the main problem was that the compressor blades tend to melt...

  • Funding? (Score:2, Interesting)

    by timeOday ( 582209 )
    I'm very impressed that this was headed by a University (versus, say, Lockheed-Martin or Nasa). The article says there were collaborators from around the globe, but who picked up the tab?
  • "After everyone had gone home, the researchers faced a nail-biting wait for the telemetry officers to come in from the dust with their precious data, before analysis could occur."

    Don't they have some form of high speed network they can just FTP the data over? Why did they have to wait for these guys to come back from remote tracking stations? Anyone know?

    --P
    • The data was recorded in a little black box that parachuted back to earth, somewhere within an n-kilometer radius for some moderately large value of n, and so it took some time to find it.

  • Success? (Score:3, Funny)

    by FJ ( 18034 ) on Friday August 16, 2002 @11:33AM (#4083212)
    It isn't too often you hear the word "success" in the same article as until it began to burn up

  • This will revolutionize worldwide air transport.

    --Blair
  • ... is mysteriously close to Paul Allen! Come on, who spells there name with all those extra L's

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