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China The Military Transportation Technology

China Builds World's Fastest Hypersonic Wind Tunnel To Simulate Flight At 27,000 MPH ( 63

schwit1 quotes a report from South China Morning Post: China is building the world's fastest wind tunnel to simulate hypersonic flight at speeds of up to 12 kilometers per second (~27,000 miles per hour). Zhao Wei, a senior scientist working on the project, said researchers aimed to have the facility up and running by around 2020 to meet the pressing demand of China's hypersonic weapon development program. "It will boost the engineering application of hypersonic technology, mostly in military sectors, by duplicating the environment of extreme hypersonic flights, so problems can be discovered and solved on the ground," said Zhao. The world's most powerful wind tunnel at present is America's LENX-X facility in Buffalo, New York state, which operates at speeds of up to 10 kilometers per second -- 30 times the speed of sound. Hypersonic aircraft are defined as vehicles that travel at speeds of Mach 5, five times the speed of sound, or above.

In the new tunnel there will be a test chamber with room for relatively large aircraft models with a wing span of almost three meters. To generate an airflow at extremely high speeds, the researchers will detonate several tubes containing a mixture of oxygen, hydrogen and nitrogen gases to create a series of explosions that can discharge one gigawatt of power within a split second, according to Zhao. The shock waves, channelled into the test chamber through a metallic tunnel, will envelope the prototype vehicle and increase the temperature over its body to 8,000 Kelvins, or 7,727 degrees Celsius, Zhao said. The new tunnel would also be used to test the scramjet, a new type of jet engine designed specifically for hypersonic flights. Traditional jet engines are not capable of handling air flows at such speeds.

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China Builds World's Fastest Hypersonic Wind Tunnel To Simulate Flight At 27,000 MPH

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  • by Anonymous Coward

    Anywhere in the world in under 30 mins. Not bad.

    • Re:Strike (Score:5, Insightful)

      by ClickOnThis ( 137803 ) on Thursday November 16, 2017 @07:35PM (#55566577) Journal

      Low earth-orbit velocity is about 17,500 mi/hr. Escape velocity is about 25,000 mi/hr. They're testing at speeds above the earth's escape velocity.

      Yes, anywhere in the world in under 30 min, but you'd need to burn lots of fuel not just to fly that fast, but also to keep yourself following the curvature of the earth, so you don't fly out into space and never come back..

      • Offtopic but it *blows my mind* that escape velocity is that god damn fast *AND* we can do it. I just googled it, it's 7 miles a SECOND. That's astronomically fast (duh)

        It's so insanely ridiculously quick, I can't fathom how the rockets can even do it, with people strapped to the front. The forces involved, the heat, the strain, the G's it's ... wow it's truly insane.

        • by Anonymous Coward

          Offtopic but it *blows my mind* that escape velocity is that god damn fast *AND* we can do it. I just googled it, it's 7 miles a SECOND. That's astronomically fast (duh)

          It's so insanely ridiculously quick, I can't fathom how the rockets can even do it, with people strapped to the front. The forces involved, the heat, the strain, the G's it's ... wow it's truly insane.

          Here you are a g-force calculator [] have fun.

          Keep in mind that a fit person can handle about 5g's although it would be very uncomfortable. In the calculator, if you enter "0" for your start and "25,000 mph" as your finish speed then enter say 5g as the "g-force" it would take about six minutes and 20 seconds to reach 25,000 mph usually that would kill or maim most people unless they were very fit or had protective clothing.

          An interesting read on heavy acceleration []. There are plenty of articles on this

      • The US has had a hypersonic weapon program for years -- called Prompt Global Strike. The idea wouldn't necessarily be to fly all the way around the world in the atmosphere; there are several delivery modes envisioned, one of which is to launch the vehicle on an ICBM; it would then re-enter the atmosphere in controlled, hypersonic flight, evading any terminal phase missile defenses like Russia's S-400.

        However there are treaty limits on ballistic missiles (regardless of their payload), and a ballistic missi

        • Hypersonic isn't stealthy. Your wake reflects radar (ionization) and sends seismic shock waves into the ground (at low altitude) that show where you are. The biggest problem with fast missiles is detecting the target at that speed. Even weak radar jamming or chaff could render your missile blind long enough to miss, and at that speed you don't have time or fuel to turn around and try again.
          • Didn't ICBMs use variations in gravity? Or at least they're rumoured to - I don't think anyone would confirm something like that.


            • by dlleigh ( 313922 )

              I don't know what they use in the real world, but I doubt they try to measure gravity. You can make gravitational maps of the Earth from an orbiting spacecraft, but that takes many many orbits and careful measurement of those orbits from the ground. An ICBM in flight simply wouldn't have the time to make such a map, and I doubt it would be communicating with ground stations either.

              The Earth is "lumpy" from a gravitational perspective so it's plausible that a highly accurate ICBM might need to take precise g

              • I think the idea is that you build a gravity variation map slowly using a satellite. Then you download that map into your ICBM which uses it to navigate.

          • by AmiMoJo ( 196126 )

            Hypersonic missiles don't use radar for targeting. They are programmed with fixed target coordinates, and most have some capability to be updated mid-flight. For moving targets like ships they rely on secondary systems like satellites and spotter aircraft, and several missiles are fired into the projected path.

            At the kinds of speeds they travel any terminal guidance is pretty limited, not least by the effective range of radar and optical systems.

      • An explosive driven wind tunnel is optimized for testing bullets not aircraft. It can't maintain flight speed long enough to test a scram jet engine in flight, and the China wind tunnel is too small to test a manned aircraft.
    • by dlleigh ( 313922 ) on Thursday November 16, 2017 @07:49PM (#55566647)
      Low Earth orbital velocity is a little under 8 km/sec, so if you're moving faster than that, you're going to be spending a lot of fuel trying to stay down, close to the Earth. In other words, much of your thrust will be needed to add extra centripetal acceleration to supplement the pull of gravity. Earth escape velocity is about 11.2 km/sec, so moving anywhere at 12 km/sec would put you at risk of never coming home again if something went wrong with your vehicle. The amount of energy required to move at these speeds is huge, and would require tremendous amounts of fuel to achieve: note the size of a rocket necessary to accelerate a satellite up to orbital velocity. This hypersonic research is weapons related. The researchers are undoubtedly interested only in small payloads going at these speeds for very brief periods of time. One application might be getting a small warhead past a warship's defenses. Another application might be ICBM reentry.
      • by Strider- ( 39683 ) on Thursday November 16, 2017 @08:20PM (#55566777)

        Well, the other bit to consider is that when you're testing scale models in a wind tunnel, depending on what you're testing you also need to scale the wind/air conditions to achieve accurate results. Often this means scaling up the airspeed and/or air pressure as you scale down the object being tested.

        Let's say I'm testing out a new design for an airliner wing. At full scale, the air flowing over it will exert a certain amount of force per area (PSI or Newtons/m^2, take your pick). Now, since it's not practical to put a full sized airliner wing into a wind tunnel, I build a 1/4 scale model, and put that in the wind tunnel. Here's the rub: if I ran the air over my 1/4 scale model at the same conditions as I were to test the full sized wing, I would be applying 1/16th the scale force. To make up for the difference, I need to either scale up the airspeed, the air pressure, or both. There are also a whole host of other weird effects that need to be taken into account.

        Anyhow, it's not just that this thing is designed to test a vehicle/weapon capable of operating at 27,000mph, but rather that it can provide realistic conditions to a scale model of the craft under test.

        • Many thanks to the Parent and the Grandparent... I'll likely be red-eyed tomorrow driving to the deer lease after spending way too much time reaearching orbital velocity conundrums and scale model wind tunnels.
          • Did you learn anything interesting worth reporting on?
            • Did you learn anything interesting worth reporting on?

              Two things so far:

              Some of the posters on here are way too f*cking smart.

              Get started reading Slashdot at your own peril when you really need a good night's sleep.

              • Some of the posters on here are way too f*cking smart.

                Well that definitely includes you. A smart person is just someone who says something you don't know.

                • A smart person is just someone who says something you don't know.

                  Well said.

                  Here's one I came across googling like a drooling idiot/imbecile/moron:

                  Escape velocity reduces as you get further away from the Earth. If you proceed upwards at a constant speed of 1 mph (which as noted will require continuous thrust to counteract gravity), you will eventually reach a distance where the escape velocity is equal to 1 mph. Then, you will have reached escape velocity and are no longer gravitationally bound to the Earth.

      • If you have a projectile going at mach 30, you don't need a warhead to destroy a warship. You just need to hit it.
        Every kilogram of mass in the projectile carries the energy of 0.017 kilotons at 12 kilometres per second.
        You'd need only 820kg to match the bomb dropped on Hiroshima.

      • Starflight: The Plane That Couldn't Land (1983) []

  • by DumbSwede ( 521261 ) <> on Thursday November 16, 2017 @07:36PM (#55566585) Homepage Journal

    Shouldn't it be Building not Builds. It won't be completed until 2020.

  • That's still Operation Plumbbob []

    • In fairness, they never intended to measure the speed of the end cap.

      However, NASA has built wind tunnles of a sort, capable of 60,000 m/s for a very short time for experiments on reentry on Jupiter. Fnu read: []

    • http://nuclearweaponarchive.or... []

      Learning to Contain Underground Nuclear Explosions

      By Dr. Robert R. Brownlee

      June 2002

      Sometime in 1956 Dr. Alvin Graves, Division Leader of the Test Division at Los Alamos told me that we were going to have to test underground in order to reduce fallout as much as possible. He asked me to see what I could learn about it by making what calculations I could.

      The temperatures and pressures generated by a nuclear explosion are such that there was considerable doubt that any underground test buried at a "reasonable" depth could be contained.

      In 1956 we were severely limited in computing capabilities-compared to nowadays they were laughable, and miniscule, and arguably nonexistent. I had the equations of state of four materials. They were air and water, aluminum and uranium. As it happens, there is a lot of aluminum in NTS soil, so I called that "earth". I called that of uranium "fire", and the others were air and water, so with earth, air, fire and water, how could I fail?

      In attempting to mock up the earth, I had some information about NTS soil densities and water content. I used a cylindrical pipe filled with air of several densities, depending upon the possible use of vacuums. I was allowed considerable freedom to choose other parameters as I wished. For example, what might the efficacy of plugs of various masses be, and where might they be placed for optimum results. I worked regularly with Bill Ogle, the deputy division leader, and we decided to have a first test in an "empty" pipe (cables were present), open at the top. Then we would do a test with a cap, and then do tests with plugs, the first one used to be in the middle of the hole, and the second one at the bottom. Thus we hoped to learn from test to test, acquiring data and information incrementally. Incidentally, the Pascal B test, and those immediately following, had a 4-foot diameter pipe. The cap welded to the top of Pascal B was four inches thick, so was of appreciable mass from a "man-handling" point of view.

      The first test of our "series" was Pascal A, with results as documented.

      For Pascal B, my calculations were designed to calculate the time and specifics of the shock wave as it reached the cap. I used yields both expected and exaggerated in my calculations, but significant ones. When I described my results to Bill Ogle, the conversation went something like this.

      Ogle: "What time does the shock arrive at the top of the pipe?"
      RRB: "Thirty one milliseconds."
      Ogle: "And what happens?"
      RRB: "The shock reflects back down the hole, but the pressures and temperatures are such that the welded cap is bound to come off the hole."
      Ogle: "How fast does it go?"
      RRB: "My calculations are irrelevant on this point. They are only valid in speaking of the shock reflection."
      Ogle: "How fast did it go?"
      RRB: "Those numbers are meaningless. I have only a vacuum above the cap. No air, no gravity, no real material strengths in the iron cap. Effectively the cap is just loose, traveling through meaningless space."
      Ogle: And how fast is it going?"

      This last question was more of a shout. Bill liked to have a direct answer to each one of his questions.

      RRB: "Six times the escape velocity from the earth."

      Bill was quite delighted with the answer, for he had never before heard a velocity given in terms of the escape velocity from the earth! There was much laughter, and the legend was now born, for Bill loved to report to anybody who cared to listen about Brownlee's units of velocity. He says the cap would escape the earth. (But of course we did not believe that would ever happen.)

      The next obvious decision was made. We'll put a high-speed movie camera looking at the cap, and see if we can measure the departure velocity.

      In the event, the cap appeared above the hole in one frame only, so there was no direct velocity measurement. A lower limit could be calculated by considering the time between frames (and I don't remember what that was), but my summary of the situation was that when last seen, it was "going like a bat!!"

      As usual, the facts never can catch up with the legend, so I am occasionally credited with launching a "man-hole cover" into space, and I am also vilified for being so stupid as not to understand masses and aerodynamics, etc, etc, and border on being a criminal for making such a claim.

      I'll add that we learned a lot with our series of low-yield tests. Plugs helped, but the closer to the nuclear device, the better. "Tamping" the device is better yet, and there are some ways to do that which are more clever than others. Mostly we learned that even an empty hole could cause a reduction to the atmosphere of as much as 90 percent, depending on specific design parameters. Later we were to see that if the hole is deep enough and the yield is high enough, an empty hole will close completely, allowing nothing whatsoever out except the initial light, which is not radioactive of course. In time, the tests became very sophisticated-and expensive, but we were able to achieve complete containment for almost every test, and for all but a handful of those that had containment "failures", nothing was detected off site. So I would judge our containment efforts to be quite successful. The case for these views are pretty well laid out in the book Caging the Dragon, by Carothers.

      But it took time and money!

      Good times, man. Good times.

  • and feed me Taco Bell. Every 2-3 minutes they'll get a blast of hot air that should meet their requirements.
  • I see we're confusing power & energy.....again

    • by Anonymous Coward

      It's actually 1.21 GW.

  • by Anonymous Coward

    How hard would it have been for the author to present the entire article in a common unit of measure. US version is 10km/s and the China version is 12km/s in two years.

  • FTA: "The new tunnel would also be used to test the scramjet, a new type of jet engine"... So not new; scramjets have been built on an experimental basis since the early 1950's: [] Wish people would edit their articles more carefully. What *is* new is that scramjets are finally becoming a practical reality and _that's_ very interesting.
  • I wonder how they achieve such accuracy.
  • Other than for reentry space vehicles - why would you, if you wanted to go at speeds like that, still travel inside our atmosphere?

  • What exactly can you heat to 7700 C without it melting and/or vaporizing?

Research is what I'm doing when I don't know what I'm doing. -- Wernher von Braun