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X-43A Hits Mach 7

quiggy writes "As previously reported, NASA tested the X-43A yesterday. The results are in, and the scramjet hit Mach 7, setting a new speed record. CNN is also reporting the story, with a note that a similar jet could be tested by the end of the year, hopefully reaching Mach 10."

26 of 405 comments (clear)

  1. sublight speed ;) by Janek+Kozicki · · Score: 5, Interesting

    1 mach = 334 m/s ,
    10 mach = 3340 m/s = 3.3 km/s ,
    speed of light c = 300 000 km/s ,
    (3 km/s)/(300 000 km/s) = 1/100 000 of c

    this engine travelled at aprox 0.00001c !

    good work scientists :)

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    1. Re:sublight speed ;) by Anonymous Coward · · Score: 5, Insightful

      I've always been under the impression that escape velocity is if a projectile was fired at ground level, and has no boosting at any later point. Space rockets are continiously accelerated upwards, and thus dont need to reach such speeds.

    2. Re:sublight speed ;) by slim-t · · Score: 5, Interesting
      Then how did that original post get modded informative? I thought physics was pre-requisite for reading slashdot.

      Seriously, there's a need for a "wrong" modifier, so people can mod such posts down without fear of recourse from meta-moderators who think the post is correct.

  2. Mach 7? by RadRafe · · Score: 5, Funny

    Isn't that a shaver? You know, the one with seven blades?

  3. Mach 10? Mach 10? by burgburgburg · · Score: 5, Funny
    The engines canna take it, Cap'n.

  4. 4 posts... by chimpo13 · · Score: 5, Funny

    and not a single Speed Racer joke. I'll reload in 30 seconds.

  5. Mach10?! by DigiShaman · · Score: 5, Interesting

    And just how do you keep something going that fast from burning up in the atmosphere?

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    1. Re:Mach10?! by costas · · Score: 5, Informative

      Mach 10 is a record for powered flight; it is not even close to the record of a man-maned craft; IIRC that goes to the Apollo reentry capsules that routinely hit Mach 27 on re-entry. So the heat problem has been solved for quite a while.

      The real problem here is that a scramjet engine is very sensitive to its input (the air coming in) as it only spends literally milliseconds in the combustion chamber. So you have to wonder what aerodynamic tricks the X-43A designers are pulling to smooth that flow before it goes into the intake. Notice the side-view of the aircraft; the belly is smooth and curvy in order to produce many small shocks ahead of the intake and slow down the air as much as possible. A terrific aerodynamic feat, I just have to wonder if it will be reproducible (i.e. stable enought and robust to any aerodynamic event) for a manned aircraft. [Yes, I am an aerodynamicist].

  6. Speed of sound by CaptBubba · · Score: 5, Informative
    For those of you wondering how to convert between Mach numbers and mph or m/s, here's a nifty java tool that lets you see how altitude affects the Mach number.

    basically the higher you go, the less air there is, and the slower sound travels. So, the mach number, which is the ratio of your speed to the speed of sound, will be higher at high altitudes if the speed is constant.

    1. Re:Speed of sound by mindstrm · · Score: 5, Informative

      Common misconception.

      The speed of sound in a gas is affected mainly by temperature... not density or pressure.

      From the page you just linked to:
      "The speed of sound depends on the state of the gas; more specifically, the square root of the temperature of the gas."

      Mach at 35,000 ft is 663mph

      Mach at 150,000 ft is 732mph

      The reason higher aircraft hit higher mach numbers is due to decreased air resistance... concorde can hit mach at 50,000 ft, but not at 20,000.. not because mach is perceptibly slower, but because there is less drag.

    2. Re:Speed of sound by Inspector+Lopez · · Score: 5, Informative

      To first order, the speed of sound does not depend upon the pressure at all; rather it depends primarily upon the mean mass density and the temperature.

      The reduction of sound speed at altitude is due to the reduction of temperature. The temperature rises again in the upper stratosphere (ozone heating) and then drops down to its coldest temperature at the mesopause (around 120 K, at 85 km). However, the temperature increases rapidly above that, getting back to room temperature by 110 km, and heading for 1000k and beyond by the time you get to LEO.

      At high altitudes the mass density is decreasing as you get more and more atomic species (e.g. O rather than O2) as well as larger fractions of light constituents (e.g. H2, H), so the speed of sound is quite high at LEO. At altitudes above the "turbopause" (somewhere around 105 km) the components of the atmosphere are no longer well-mixed, thus the different component gases stand at their own scale heights.

      see scale height and speed of sound

  7. CNN gets it wrong by AlecC · · Score: 5, Informative

    It also could drastically cut the time of commercial flights -- perhaps shortening the trip between New York and London to less than five hours.

    Considering Concorde did that in three hours, thit wouldn't be much achievement. I make it that it could do NY-LON in just over one hour.

    What I think they should have said is that it could go from any point on the earth to any other, including the antipodes, in less than five hours.

    Mind you, it would take three hours to get through security on departure and an hour on arrival to collect your baggage, if it had arrived with you.

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    1. Re:CNN gets it wrong by openmtl · · Score: 5, Funny
      The new trans-Atlantic flight time is now 6 hours....
      Midtown to JFK - 1 hour (off peak)
      JFK TIA/Homeland/Patriot-enabled security -> Plane seat - 3 Hours
      US -> UK flight time in new Mach 10 rocket - 2 Hours

      Total time 6 hours. Your bags though would arrive 2 days later assuming that they hadn't been blown up in an anti-terrorist "controlled explosion" at LAX.

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  8. Re:At the present rate by Boccaccio · · Score: 5, Insightful

    when will we see warp engines? Shortly after someone proves that its not impossible I guess.

  9. Re:Stupid, Slightly OT Question by Anonymous Coward · · Score: 5, Insightful

    Turns out oxygen is heavy, and kind of a pain in the ass to package anyway. It's much more convienent if you can just use the oxygen that's laying about, which is significantly more difficult that it sounds when you're traveling at hypersonic speeds.

    Damn gravity.

  10. How fast .. by the+eric+conspiracy · · Score: 5, Funny

    new speed record

    African or European?

  11. X 15 by p51d007 · · Score: 5, Informative

    Yeah, Pete Knight went to Mach 6.7 in Oct 67....STILL a record to this day, for a MANNED airplane (X-15 isn't "really" a traditional airplane since it is air launched). Also Pete Knight earned astronaut wings by flying the X15 near 300,000 feet. Several of the X15 pilots received astronaut wings by flying near or over 300,000 feet. Joe Walker, went the highest to 320,000 feet! Sadly, he was killed in the 60's when he was in a formation of planes for an Ad for the general electric engines that all the planes were flying. His "tiny" in comparison jet got too close to the XB-70 bomber (which was suppose to be a Mach 3+ bomber) and it went inverted and smashed into the tail of the bomber, and exploded. Sorry, the early years of test pilots, NASA has always fasinated me, and buddies of mine call me a walking encyclopedia of aircraft knowledge ;)

  12. SCRamjet = Supersonic Combustion Ramjet by amigoro · · Score: 5, Informative
    So what's a Ramjet?

    There's one fundamental difference between an ordinary jet engine and a scram jet engine: The Ramjet has no moving parts.

    The all jet engines,operate according to Newton's Third Law of Motion:
    For every action, there's an equal opposite reaction

    The standard jet engine, invented by Sir Frank Whittle, sucks in air at the front. Then this air is mixed with fuel, and made to combust. The combustion causes the air to exit the engine at a velocity greater than when it came in, thus creating thrust. The escaping air causes the turbine to spin, and this intern activates the compressor, sucking more air in.

    The Ramjet has no turbine and compressor unit. Ramjets fly supersonically and have an inlet which injests subsonic air after it goes through a shock wave in front of the inlet. The intake is slowed down aerodynamically, and then mixed with fuel and made to combust. But after about Mach 5, ramjets don't work so well.

    The scramjet is almost but not quite entirely like a ramjet. The only difference being in a scramjet the combustion takes place as the air is travelling through the chamber at supersonic velocities.

    More about the scram jet. Or another more concise explanation.

    Moderate this comment
    Negative: Offtopic Flamebait Troll Redundant
    Positive: Insightful Interesting Informative Funny

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  13. Re:Stupid, Slightly OT Question by mindstrm · · Score: 5, Informative

    It's not. This whole experiment is not at all about speed, and everything about a new engine design.

    IIRC, Mach5 is the speed at which the scramjet is released, and ignited... up until then it's just being boosted by a conventional rocket.
    During the first test, the scramjet failed.

    During this test, it worked, pushing the rocket up another mach or two.

    This was not meant to be any kind of speed record.. that's just how fast you need to go to get a scramjet working.

  14. Re:Stupid, Slightly OT Question by Anonymous Coward · · Score: 5, Informative

    No, during the first test the rocket booster (the Pegasus) failed, mostly due to being released too low in the thick atmosphere. The entire package was destroyed by mission control before it went totally out of control.

  15. THE PROGRAM IS BEING HALTED! by wisebabo · · Score: 5, Interesting

    There's an old Airforce saying:
    A new plane doesn't make a new engine possible: A new engine makes a new plane possible.

    That's why when NASA went for the moon a critical development was the F-1 first stage rocket engine. Capable of 1.5M lbs. of thrust it allowed the Saturn V first stage to be built with only 5 engines. Compare this with the Russian failed manned lunar rocket the N-1 which had 20 engines. They never were able to work all together (vibrational problems) and abandoned it after several launch disasters.

    So why is NASA stopping development? (The successor the X-43C will not be flown). Why are we freezing this enabling technology? Are we (under Bush's program) sacrificing everything to plant a flag on Mars and not making space flight practical? It might be worth it if we ever got to Mars but it looks highly doubtful that his proposal is a serious attempt at anything but votes!

    Sorry for the (mostly) repost but I really wish we would move "faster" towards developing the technologies towards practical* spaceflight.

    *As noted in previous posts, by not carrying the oxygen on board you save a LOT of weight. Remember the reaction is H2 + O = H2O (and energy) and since the atomic weight of oxygen is 16 compared to hydrogen for every kilo of hydrogen you carry you carry EIGHT of oxygen. The weight savings (could be in the millions of pounds) makes up for the turbo-fans/rocket engines you must carry for the takeoff/orbital transition parts of the flight.

  16. Re:Mach 10 by dynoman7 · · Score: 5, Funny

    mach 10 = 20461245.5 furlongs per fortnight

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  17. Armchair physicists are idiots by Anonymous Coward · · Score: 5, Informative

    Let's sum it all up. 1) Escape velocity is IRRELEVANT in the discussion. That applies to unpowered vehicles - not a vehicle under constant power such as this one.

    2) As has been already posted. The speed record isn't for ANY vehicle. The record is for a vehicle with an air breathing engine (ramjet, scramjet, etc). It doesn't apply to vehicles such as the X-15, Apollo capsules, the space shuttles, etc as their speeds were/are either rocket powered or unpowered reentry.

    3) During the first test the scramjet engine did NOT fail. It was never even fired. The booster engine that was supposed to get the scramjet to mach 5 is what failed. If I remember right the fins or something fell off and it went out of control so the remote detonated the booster and consequently the scramjet testbed attached to it.

    4) The toyota corolla attachment won't be out until 2006.

  18. Uhh guys...this has been done before by shthd · · Score: 5, Informative

    From cnn It is the first time a supersonic-combustion ramjet, or scramjet, which uses air for fuel, had traveled so fast, flight engineer Lawrence Huebner told reporters. The University of Queensland Launched the HYSHOT in July 2002. It Hit Mach 7.6. The first people who did this

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  19. Re:At the present rate by alphorn · · Score: 5, Funny

    it's not impossible, it's just infinitely improbable.

  20. Not exactly the same... by Dan+East · · Score: 5, Insightful

    http://www.mech.uq.edu.au/hyper/hyshot/:
    As the spent motor and its attached payload falls back to Earth, they gather speed, and the trajectory is designed so that between 35km and 23km, they are travelling at Mach 7.6

    http://www.uq.edu.au/news/index.phtml?article=3469 :
    The recent HyShot(TM) launch was designed to take the scramjet engine to a speed of Mach 7.6 (or more than seven times the speed of sound) for the experiment, using a Terrier Orion rocket. The rocket and payload reached an altitude of 314km before the rocket was configured to fly in a new trajectory pointing the payload back down to earth.

    HyShot was simply free-falling to earth in order to reach Mach 7.6 so the engine could be ignited. It achieved that speed regardless of whether or not the scramjet fired. The X-43 was flying horizontally, and was actually powered by the scramjet engine during a controlled flight.

    So there is a difference between what was accomplished. The distinction is that HyShot achieved combustion, while the X-43 was the first scramjet powered craft to be flown.

    Dan East

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