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NASA to Attempt Mach 10 Flight Next Week

Dirak writes "NASA intends to break its own aircraft-speed record for the second time this year by flying X43a scramjet ten times faster than sound. On November 15 the X-43A supersonic-combustion ramjet - or scramjet - will again take to the skies aiming for Mach 10."

67 of 357 comments (clear)

  1. What is the Speed of Sound? by Anonymous Coward · · Score: 5, Insightful

    Just above the atmosphere, what is the speed of sound? I guess when an article says 10 times the speed of sound it means the speed of sound at sea level right? But this aircraft isn't at sea level. This aircraft skips on top of the atmosphere pulsing the scramjets while dropping into the atmosphere.

    The speed of sound isn't a good tool to measure the speed, as the speed of sound without an atmosphere is either infinite, undefined, zero or a combination of the choices. I mean once you get into space, should you add the speed the earth is rotating plus the speed around the sun using a basis of sound?

    1. Re:What is the Speed of Sound? by Anonymous Coward · · Score: 2, Funny

      Speed of sound in a vacuum?

      Just a guess. ;)

    2. Re:What is the Speed of Sound? by kuwan · · Score: 3, Informative

      From the article:

      The final flight in the Hyper-X program is scheduled to take place in October, when another X-43A aircraft will attempt to fly at Mach 10 -- ten times the speed of sound -- or 7,200 mph.

      So if 10x the speed of sound is 7,200 mph, then the speed of sound is roughly 720 mph.

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    3. Re:What is the Speed of Sound? by quizwedge · · Score: 3, Funny

      In Space... No One Can Hear You Scream

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    4. Re:What is the Speed of Sound? by Dr.+GeneMachine · · Score: 4, Funny

      You surely meant
      In Space... No One Can Hear You Scram

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    5. Re:What is the Speed of Sound? by Anonymous Coward · · Score: 2, Informative

      Not really. Your average airliner will do about mach 0.83. Thats a useful thing for a pilot / engine maintainer to know and deal with, and they don't do it at sea level. The speed of sound in air will change depending on its density and temperature. So mach 1 at sea level probably isn't the same as where this thing will fly.
      Let's see:
      Speed of sound
      And then you have the fun of working out its real air speed vs ground speed (its progress in going from A to B on surface), which is why you were flying to begin with. :)

    6. Re:What is the Speed of Sound? by mog007 · · Score: 2, Interesting

      That's not really a speed record, considering the space shuttle hits, what, around 22,000 miles per hour?

    7. Re:What is the Speed of Sound? by bleckywelcky · · Score: 4, Informative

      It's a record for an air-breathing engine. The SS get's lofted into orbit by self-contained solid rocket boosters that carry fuel and oxidizer together and burn it without air and then drops out of orbit. An air-breathing engine carries fuel with it and adds that to the surrounding air and pushes it all through it's combustion chamber.

    8. Re:What is the Speed of Sound? by ab762 · · Score: 4, Interesting

      Precisely - Mach 1 is the local speed of sound. Specifically, it's the velocity at which shockwaves propagate. If you are flying at Mach 1 (plus delta) you are encountering a medium which is uninfluenced by your motion until you encounter it - it doesn't have time to get out of the way. That makes a huge difference to the behavior, a little like the difference between swimming in water and swimming in concrete!

      There is, of course, a FAQ on this Frequently Asked Question.

    9. Re:What is the Speed of Sound? by Anonymous Coward · · Score: 2, Interesting

      "but most obviously, sonic booms always appear as soon as the aircraft goes as fast as the speed of sound"

      Actually, they begin to appear when there is transonic airflow anywhere. This can be well before the aircraft is exceeding the speed of sound, since air flows around the aircraft at different rates depending on location.

      Sonic "booms", as heard on the ground, are more dependent on the shape of the aircraft than the speed at which it is travelling. I can generate a sonic boom by swinging a piece of notebook paper folded appropriately. If my hand were actually travelling at the speed of sound, I'd have a healthy collection of Cy Young awards at this point.

    10. Re:What is the Speed of Sound? by kuwan · · Score: 4, Informative
      The space shuttle isn't designed to fly like an airplane, it (like other rockets) are designed to get you into space. If you'll read a little more of the article:
      The accomplishment will be included in the 2006 Guinness World Records book, set for release this time next year, as follows:

      "On 27 March 2004, NASA's unmanned Hyper-X (X-43A) airplane reached Mach 6.83, almost seven times the speed of sound. The X-43A was boosted to an altitude of 29,000 m (95,000 ft) by a Pegasus rocket launched from beneath a B52-B aircraft. The revolutionary 'scramjet' aircraft then burned its engine for around 11 seconds during flight over the Pacific Ocean."

      ...

      The X-43A flight easily set a world speed record for an air-breathing engine aircraft. The previous known record was held by a ramjet-powered missile, which achieved slightly more than Mach 5. A ramjet operates by subsonic combustion of fuel in a stream of air compressed by the forward speed of the aircraft itself, as opposed to a normal jet engine, in which the compressor section (the fan blades) compresses the air. A scramjet (supersonic-combustion ramjet) is a ramjet engine in which the airflow through the whole engine remains supersonic.

      The highest speed attained by a rocket-powered airplane, NASA's X-15 aircraft, was Mach 6.7. The fastest air-breathing, manned vehicle, the SR-71, achieved slightly more than Mach 3. The X-43A more than doubled the top speed of the jet-powered SR-71.
      An airplane that goes Mach 10 will be an amazing achievement for an air-breathing engine (a.k.a. non-rocket) aircraft.
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    11. Re:What is the Speed of Sound? by AyeRoxor! · · Score: 4, Informative

      Just like 1 Atmosphere is air pressure at sea level, Mach 1 is the speed of sound at sea level.

      Interestingly enough, according to Google Math, Mach 10 is ~127 miles a minute. Assuming it takes them at least 5 or 10 minutes to achieve Mach 10 (I have no frigging idea), they are going to cover some serious distance. Sheesh.

      At Mach 10, you will circle the Earth in under 200 minutes.

      Damn I love Google math.

    12. Re:What is the Speed of Sound? by caswelmo · · Score: 3, Insightful

      If there's no sound, there's no oxygen. If there's no oxygen, there's no boom. If there's no boom, there's no vroom. It's an air-breather.

    13. Re:What is the Speed of Sound? by 955301 · · Score: 2, Funny

      I am married and an engineer?
      I am mauling an Aeronautical Engineer?

      --
      You are checking your backups, aren't you?
    14. Re:What is the Speed of Sound? by Belzu · · Score: 2, Funny

      Sound does travel through the 'vacuum.' As any self respecting scientist will know, the medium through the sound propagates is the 'Aether,' a very diffuse, gas-like material.

    15. Re:What is the Speed of Sound? by Moofie · · Score: 2, Informative

      The speed of sound is a CRITICAL tool for measuring the speed of these types of aircraft. Not for the "my airplane is faster than your airplane!" nonsense, but because all the maths for calculating the performance of high speed aircraft are based on Mach number (ratio of current speed to local speed of sound), not groundspeed or airspeed.

      The speed of sound "above the atmosphere" is undefined. There is no sound. There are no air molecules to a) fly on top of or b) propagate shock waves through. The speed of sound at the altitudes where wing-borne air breathing hypersonic aircraft operate is NOT undefined. It is one of their most important metrics.

      --
      Why yes, I AM a rocket scientist!
    16. Re:What is the Speed of Sound? by Jetson · · Score: 4, Informative
      I guess when an article says 10 times the speed of sound it means the speed of sound at sea level right?

      Mach "speed" is expressed as a ratio and is usually relative to the local environment. You can increase your Mach ratio either by climbing at a constant absolute speed or by accelerating at a constant altitude (although climbing at an increasing absolute speed works best :-P).

      The problem with using altitude to improve your Mach ratio is that it decreases your indicated airspeed (the air felt by the wings). There comes a certain point with some high-performance aircraft where the indicated airspeed is just above stall and the Mach ratio is just below the aircraft's design limit. This is called the "coffin corner" because once you reach that speed/altitude it's virtually impossible to descend or slow down without losing control of (or destroying) the aircraft.

      Rutan's Space Ship One solved this problem by intentionally stalling the aircraft in a stable high-drag attitude and staying in that configuration until safely back into the flight envelope.

    17. Re:What is the Speed of Sound? by silence535 · · Score: 3, Funny

      but dosen't sound NOT travel through a vacuum?

      Of course it does, otherwise we could not hear the Tie-Fighters screech past.

      --
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    18. Re:What is the Speed of Sound? by mwood · · Score: 2, Funny

      Belzu, may I present Messrs. Michelson and Morley, who would like to talk with you about this 'aether' jazz.

  2. Risky? by MycroftMkIV · · Score: 2, Funny

    I don't know how this can be risky. No one will be in the thing when they fly it. How is that risky?

    Mike

  3. W00T! by Anonymous Coward · · Score: 3, Funny

    Now they can hurtle spacecraft towards Mars even faster before they malfunction and drift into outer space :D

  4. Flying faster than a first post... by Anonymous Coward · · Score: 2, Funny

    Mach 10? Call me when you hit Warp 1, then we'll talk.

  5. To Bad for the sonic Boom. by jellomizer · · Score: 4, Interesting

    All this extra speed will not be available for the common public until they can resolve the problem with the sonic boom. Once that is resolved I think it would be a lot more interesting where they could have supersonic flights that go over land as well. And the general public will advance. Right now having an airplain that can go at Mach 10 is somewhat useless because we can already out fly our enemies planes which most were build during the cold war times.

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    1. Re:To Bad for the sonic Boom. by Saltine+Cracker · · Score: 3, Interesting

      At an altitude of 110,000 feet, I don't think surface dwellers need to worry too much about sonic booms.

      Or is the point of your post that the Government shouldn't fund research unless it's fruits can be made readily available to the public?

    2. Re:To Bad for the sonic Boom. by Cheeko · · Score: 4, Informative

      I think there is little to no interest in this as far as combat aircraft. NASA's main interest is in using scramjets to produce aircraft like vehicles that can "fly" into space affordably. As I understand it aside from their ability to operate at high speeds more efficiently than rockets, they also allow for much higher altitude functionality than a standard jet engine. This would allow a space plane to get high in the atmosphere, then use a small rocket boost to get into orbit.

      I believe the idea behind a functional vehicle would be something like a standard jet engine getting a craft up to mach 1 or 2, then a ramjet taking over and getting a craft up to mach 5 or so, and then a scramjet taking a ship up to mach 10-15, at which point a rocket boost pushes it through the last bit of thin atmosphere into orbit. I may be wrong, as my knowledge on this was material read 4-5 years ago, but that seems to be what I remember.

      Supposedly a nother great thing about scramjets is their simplicity, very few moving parts, which allows for high reliability. Or as high reliability as can be expected for something working under the strain of Mach 10.

    3. Re:To Bad for the sonic Boom. by Kaboom13 · · Score: 2, Informative

      The sonic boom is far from the only reason we dont have public Mach 1+ aircraft (except the concorde, now defunct). Every aircraft has an optimum speed for maximum fuel effeciency. This speed is below the speed of sound on every aircraft (well except maybe for aircraft designed to break speed barriers, but they burn fuel insanely fast even at optimum). Air craft fuel is expensive, and the more you have to carry the less you can lift (because you now have to lift the extra fuel on take-off). Faster than sound air travel will always be a luxury.

    4. Re:To Bad for the sonic Boom. by Anonymous Coward · · Score: 2, Interesting

      The primary military application for this technology would be for cruise missiles. The U.S. is by their own account 10 years behind Russia in cruise missile technology. The Russian SS-N-22 Sunburn Missile uses airbreathing ramjet technology and flies at roughly Mach 3, making it the most feared cruise missile in the world. The Russians have exported this (primarily anti-ship) missile technology to China and is also jointly developing a similar cruise missile with India which was test fired recently.

      The U.S. would love to have a mach 10 cruise missile to counter this threat since their Tomahawk cruise missiles are inferior as they fly at subsonic speeds. As it is now, a Chinese or Russian destroyer/sub/plane could take out an aircraft carrier with one Sunburn missile that flies at a cruising altitude of 40 feet and is too fast for on board (phalanx) anti-missile systems to defend against.

    5. Re:To Bad for the sonic Boom. by Moofie · · Score: 2, Informative

      Ramjets cannot operate subsonically. Operating speed for a ramjet is approximately Mach 3 to Mach 7. Above Mach 7, you need a scramjet.

      All these numbers are approximate. I can provide more excruciating detail than you likely want. : )

      --
      Why yes, I AM a rocket scientist!
    6. Re:To Bad for the sonic Boom. by PantsWearer · · Score: 2, Interesting
      Yeah, but how often do bombers get into dogfights?

      You can't dogfight at Mach 10 (or really Mach anything), so what's left? A bomber. This would seriously ease a nation's dependence on foreign bases since the airfield could be halfway around the world. I'm sure the various air forces would love this kind of thing since it would partially take back some of what aircraft carriers have removed from air force influence.

      --
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  6. One step closer to by jaguar5150 · · Score: 4, Funny

    Ludicrous Speed!

    1. Re:One step closer to by shadow303 · · Score: 2, Informative

      It is the same as plaid speed.

      --
      I've got a mind like a steel trap - it's got an animal's foot stuck in it.
  7. Practical application by darco · · Score: 3, Funny

    I'm all for fast cool stuff, and technical gadgetry, but anyone know of any practical uses for this? I mean, wouldn't it run into the same sonic boom issues as the concorde? Perhaps even worse?

    Or is this just a method for getting something to go fast enough to put it into orbit without a rocket? (which would be quite useful)

    --
    — darco
    1. Re:Practical application by trybywrench · · Score: 3, Insightful

      I'm all for fast cool stuff, and technical gadgetry, but anyone know of any practical uses for this? I mean, wouldn't it run into the same sonic boom issues as the concorde? Perhaps even worse?

      This would make an incredibly formidable cruise missile. You could launch it basically from anywhere in the world and it would arrive on target within a couple of hours. No near-deployment required.. you could launch it from your backyard in Nebraska. I'm all for peace, smiles and sunshine but the military uses for this are incredible.

      --
      I came to the datacenter drunk with a fake ID, don't you want to be just like me?
  8. Comment removed by account_deleted · · Score: 2, Insightful

    Comment removed based on user account deletion

  9. The B-52 by OverlordQ · · Score: 3, Insightful

    The B-52, the American workhorse for over 50 years. So called 'Weapons of War' can be used for other, good purposes, like this.

    --
    Your hair look like poop, Bob! - Wanker.
  10. Lets hope for success by CrashPanic · · Score: 2, Interesting

    NASA really needs this technology. If it can be made practical it should largely solve the inexpensive-access-to-LEO problem tat has plagued us since the beginning of the space age.

    --
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  11. Re:Fast times at tax-payers' expense by ThosLives · · Score: 3, Informative
    Maybe we can practice other completely unnecessary acts of money waste.
    You mean like spend $125 Million on a video game? That does almost absolutely nothing to advance society at all?

    I'm tired of hearing people yap about tax money when they waste money on frivolous things. Not to say that video games are bad, but do you know how much health care or education $125 Million will purchase? And the general public dropped that in one day! Do you know how much good research $125 M will purchase? I haven't looked it up, but I'm guessing the X-43A project is on the same order of magnitude cost-wise as what the public spent on this one single video game.

    --
    "There are a dozen opinions on a matter until you know the truth. Then there is only one." - CS Lewis (paraprhase)
  12. Perfect cycle by IGnatius+T+Foobar · · Score: 3, Funny

    I'm sure this aircraft will create a lot of wind when it goes by. This wind can then be harnessed by windmills, which will produce electricity. The electricity can be used for electrolysis, producing hydrogen. The hydrogen can be converted into jet fuel. It's the perfect cycle!

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    1. Re:Perfect cycle by beta21 · · Score: 2, Funny

      Lisa in this house we obey the laws of thermodynamics

  13. Final Flight by SimURL · · Score: 5, Interesting

    If successful it would be a great accomplishment. However, according to this Wired article
    http://www.wired.com/news/technology/0,1282,65671, 00.html?tw=wn_tophead_3,
    NASA is "phasing out its hypersonic engine program to free up funding for President Bush's 'Vision for Space Exploration,' which calls on NASA to focus its energy on sending humans to the moon and Mars."

    Therefore,
    "As of now, next week's X-43A flight is the final flight in the $230 million program."

    I can't help but wonder if these priorities are correct as I'm not quite sure what we intend to do after we reach the moon and Mars.

  14. Not that archaic by mdp1173 · · Score: 2, Informative

    Mach number is not just the speed of sound in air at sea level. It is used by mechanical engineers all the time because it applies to ALL fluids. Every fluid (yes, air is a fluid) has a Mach number. Mach numbers are useful in many types of calculations other than "the speed when you hear the boom"

  15. Re:Very Cool, But... by RetiredMidn · · Score: 2, Informative
    f the only applictaion is high performance aircraft (Air Force Fighters) why isn't it being developed by DARPA, leaving NASAs (much smaller) budget for projects that might actually benefit space exploration?

    Well, NASA stands for National Aeronautics and Space Administration; this is well within the original (1915) charter of the organization, which was called the National Advisory Committee for Aeronautics (NACA) before space exploration was added to their role along with the name change in 1958.

    Besides, this project is in the tradition of the X-1 thru the X-15, all NASA projects, IIRC. NASA drives the research, but it's private industry (Lockheed, Douglas-Martin, Boeing) that figures out how to build 'em, and we end up riding in better airliners, eventually.

  16. Re:Very Cool, But... by susano_otter · · Score: 3, Interesting

    I think that if the theoretical parameters of the ideal scramjet play out in practice, they'll be a very efficient motor for getting things into low earth orbit.

    Sure, they don't work outside the atmosphere, but what about a next-gen shuttle that develops most of its thrust during the scramjet phase, uses a small rocket motor to get that extra bit of velocity at the upper end, and still has enough room left over for some worthwhile payload?

    I imagine that's the kind of thing NASA's interested in.

    Space Ship Two, anyone?

    --

    Any sufficiently well-organized community is indistinguishable from Government.

  17. Re:Fast times at tax-payers' expense by pi_rules · · Score: 2, Insightful
    do you know how much health care or education $125 Million will purchase?


    Yeah, a couple of Band-aid's and a pencil or two for every citizen.

    You could build, maybe, 8 schools with that kinda cash.

    Woooooo!
  18. Blackbird and the Swedish fighter Viggen by 3770 · · Score: 4, Interesting

    The U.S. Blackbird spy plane was _really_ fast when it came out. It is still probably one of the fastest aircrafts out there. Maybe still the fastest.

    The Swedish fighter jet, Viggen (which is built by SAAB) was the first fighter plane to ever get a "lock" on the blackbird.

    The Swedish radar systems got it on radar. The Viggen flew to intercept it with after burners on the whole time.

    It got a lock on it and then had to turn back because it was out of fuel. There was of course never any intention of firing a missile, but still.

    The black bird crew sent a box of chocolate to the Swedish air base and said "Congratulations!".

    At least, this is what I heard. Whether it really is true, I couldn't tell you for sure.

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    1. Re:Blackbird and the Swedish fighter Viggen by acc2 · · Score: 3, Funny

      But, but, Bush told me Sweden don't have any army! I'm comfused...

    2. Re:Blackbird and the Swedish fighter Viggen by div_B · · Score: 2, Informative

      The Swedish fighter jet, Viggen (which is built by SAAB) was the first fighter plane to ever get a "lock" on the blackbird.

      The Swedish radar systems got it on radar. The Viggen flew to intercept it with after burners on the whole time.


      They would have had to have picked it up on radar (on approach) a LONG way out, given how insanely fast SR-71s are. From the wiki:

      On July 28, 1976, an SR-71 set two world records for its class: an absolute speed record of 2,193.167 mph (3,529.56 km/h) and an absolute altitude record of 85,068.997 feet (25,929 m). When the SR-71 was retired in 1990, one was flown from Palmdale Airbase to go on exhibit at the Smithsonian Institute's National Air & Space Museum in Washington, D.C., setting a coast-to-coast speed record at an average 2,124 mph (3,418 km/h). The entire trip took only 68 minutes.

      The aircraft flew so fast and so high that if the pilot detected that a surface-to-air missile had been launched, the standard process of evasive action was, simply, "accelerate". No SR-71 aircraft are known to have been shot down.


    3. Re:Blackbird and the Swedish fighter Viggen by Jakob+Eriksson · · Score: 2, Informative

      Always the same with you Americans! :-D

      Sweden != Switzerland. Sweden may be famous for its socialist government, ABBA, and Ericsson, but certainly not chocolate.

      What's more insulting: getting a box of chocolates, or getting confused with an entirely different country?

    4. Re:Blackbird and the Swedish fighter Viggen by Chuck+Chunder · · Score: 2, Funny

      Is that you George?

      --
      Boffoonery - downloadable Comedy Benefit for Bletchley Park
  19. Re:Too Bad for the sonic Boom. by mi · · Score: 2, Interesting
    Right now having an airplain that can go at Mach 10 is somewhat useless because we can already out fly our enemies planes which most were build during the cold war times.

    First, we sill can not outfly some of the enemy's missiles and have to outmaneuver and/or outsmart them. Second, the faster we can go the farther we can fly on time. For example, the planes can be based on the comfortable island but still be able to timely reach some of the theaters, where expensive and uncomfortable carriers have to be used now.

    Lastly, using the technology for our missiles would be great too -- for example, once information comes in where a thug can be hit, this missile can reach his bunker in 20-30 minutes, rather than 2 hours. Not to mention the potential of replacing the "old-and-boring" ICBMs.

    --
    In Soviet Washington the swamp drains you.
  20. Re:Fast times at tax-payers' expense by audacity242 · · Score: 2, Interesting

    Who knows, there may be a good use for this.

    It always irked me that in psychology, research done for the basis of learning stuff and not really improving anything is referred to as "basic" research (in most other disciplines, it's referred to as "pure" research). Whether you call it pure or basic, this sort of research may not have any immediate uses, but it may very well be something that spurns someone to do some applied research.

    -Jenn

  21. Another interesting propulsion design by azcoffeehabit · · Score: 2, Interesting

    Here is another interesting propulsion design. Anyone have any insight into this technology. Glow Discharge Plasma. Does this technology have promise? How about for space travel? Obviously a scramjet needs oxygen which makes space travel a little difficult.

    --
    :)(smile)
  22. This is what NASA is meant FOR by Thud457 · · Score: 5, Insightful
    People, people. This is what NASA should be doing. Basic aeronautical research.

    Then some smartass hillbilly with nine-inch sideburns can make use of their research to build a rocketplane and proclaim : "Spaceship 2, Government 0"!

    --

    the preceding comment is my own and in no way reflects the opinion of the Joint Chiefs of Staff

  23. Rockets vs. Jet Engines by hey! · · Score: 4, Insightful

    Yes, but the shuttle is launched by rockets, not jet engines.

    I am not an aeronautical engineer or even much of a space buff by /. standards, but my understanding of the situation is that rockets carry both fuel and oxygen, whereas jets carry just fuel and breathe oxygen from the atmosphere. What I think this means is that to the degree you can get the speed you need to access space using a jet in the atmosphere, you can dispense with carrying some of the oxygen.

    Again, in my naive, non expert way, I look at a typical rocket and see a huge cylinder of fuel and oxidant with a teeny tiny payload on top. Even a marginal reduction in the size of the non-payload part has got to make a big difference in cost per pound of payload. I'm guessing this is leading to systems in which the first stage to orbit consists of a reusable scramjet powered vehicle that takes the next stage above the atmosphere.

    --
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  24. Re:What are the Vegas Odds of this working? by IdahoEv · · Score: 2, Insightful

    I don't think it will. I just doubt the plane will hold together with that much pressure on it

    Why not? The Space Shuttle goes more than twice that fast during reentry into the atmosphere, and held together under "that much pressure" more that a hundred consecutive times. It only failed last time because of gross damage to the leading edge of a wing.

    You don't think NASA's engineers are smart enough to calculate the pressure at mach 10 and build accordingly?

    I wouldn't be too stunned if the flight fails (since it is a new technology), but I doubt it will be from the hull being to weak to withstand the forces placed on it at speed.

    --
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  25. It means Mach 10 at the altitude it will be flying by i41Overlord · · Score: 3, Interesting

    It will be 10 times the speed of sound at the altitude the craft will be flying.

    You can't take the sea level speed of mach and multiply it by 10, because that would be incorrect. The speed of sound is about 760 mph at sea level, while at 95,000 feet (where the HyperX flies), the speed of sound is about 677 mph.

    So when it flies Mach 10 it is not going 7,600 mph, it is going 6770 mph.

    This is a common mistake that I see being made. Same thing with the SR-71...it is often quoted by dumb journalists as going 2280 mph, which is Mach 3 at speed level. But it can't go Mach 3 at speed level, it would break apart. It goes Mach 3 at 85,000 feet, which is about 1992 mph.

    There's a cool utility for calculating Mach here: http://www.grc.nasa.gov/WWW/K-12/airplane/sound.ht ml

  26. Re:is it REALLY an "Aircraft"? by Control+Group · · Score: 2, Insightful
    Yes. A rocket is entirely self-contained: its fuel and reaction mass are both stored internally (and are generally the same thing, in point of fact)*. The scramjet carries its fuel onboard, but the reaction mass is the atmosphere.

    *Actually, it's possible that the term "rocket" specifically means that the fuel and the reaction mass are the same thing, but I'm not certain of that, since I've seen terms like "nuclear rocket" used quite often (though perhaps incorrectly), and those do decouple fuel and reaction mass.

    --

    Reality has a conservative bias: it conserves mass, energy, momentum...
  27. Re:Poor budget managment. by HokieJP · · Score: 2, Insightful

    Your understanding is not correct.

    NASA and the Air Force were going to co-operate on the X43-C project (a follow on to the X43-A), but it was cancelled. However, hypersonics research at NASA is not over. You can read all about it here.

    One reason why it makes sense for NASA to work on this is that the technology may be used to improve access to space. This is not an avenue the USAF is likely to pursue.

  28. Aviation Technology Week's take on Scramjet by DumbSwede · · Score: 4, Insightful
    On the downside I read a recent Aviation Technology Week that states that the Mach 10 flight is the end of current funding for Hypersonic Flight research. Evidently there are not concrete plans to keep going even if this flight is a success, though it seems unlikely NASA would let the program die completely (like other X projects).

    Also stated in the ATW was that there wasn't (or shouldn't) be any animosity between the Scramjet team and the Rocket technology teams, in that affordable scramjet is projected to top out in the 20,000 lbs to LEO range and have a $1,700 per pound price tag vs $2,200 for expendable rocket, but with rocket being able to heft much larger loads. Still, the 20,000 lbs range is projected to meet 80% of future lift needs.

    This figures struck me has oddly pessimistic, but they see problems scaling with this technology. They think the real advantage to scramjet will be reliability, with current unmanned failures rates (and manned it would seem also) at one in 50, and scramjet figured at 1 in 4000 or so (assuming a return to Earth on propulsion failure). Of course the Shuttle was projected to have a low failure rate also.

    Still I would think a four-tier approach would be near ideal for now.
    Maglev assist takeoff to Mach 1 or 2
    Jet assist to Mach 3 or 4 (stubby winged, high-speed, jet wouldn't have enough lift for loaded takeoff on it's own)
    Scramjet to Mach 8 or 10
    Rocket final stage to Mach 22 orbit.

    Maybe Congress doesn't want to fund this because they're misreading Scramjet as Scam-Jet.

  29. Re:is it REALLY an "Aircraft"? by pk2000 · · Score: 2, Informative

    rocket - carries fuel and oxygen
    plane - carries fuel but takes oxygen from atmospher

  30. Re:Very Cool, But... by Control+Group · · Score: 2, Interesting
    Exactly. Somewhat apocryphally (from the reader's POV) since I can't be bothered to dig up the links: I seem to recall theoretical max on scramjet tech being Mach ~20. I also recall reading a paper on orbiting tethers for boosting into LEO stating that you could increase the payload from ~1% of total launch mass to ~4% of total launch mass if you could drop the target velocity from Mach ~23 to Mach ~18.

    So if the rocket only has to get from Mach ~20 to Mach ~23, I would imagine the payload increase to be significant (the increase is, of course, offset by needing to have the scramjet and initial lifting bodies as well as fuel therefore...but the initial/scramjet stages don't have to carry oxidizer or reaction mass, which gives them a huge mass advantage over conventional rockets).

    --

    Reality has a conservative bias: it conserves mass, energy, momentum...
  31. Re:Great by IHateSlashDot · · Score: 3, Interesting

    Did everybody wake up and take a stupid pill this morning or something? The arguments about this being too fast for commercial flight are in the same vein as early arguments that noboby would ever need more than 64KB of memory. Of course this is acceptable speed for commercial flights. It'll take a while to get there, but it will happen

  32. I've heard similar stories. by i41Overlord · · Score: 2, Insightful

    I've read plenty of stories from Blackbird pilots on usenet, and it sounds like getting a lock on a Blackbird is not hard at all. You can track satellites by radar, too, but you'll have a hell of a time trying to shoot one down. The problem is getting your missile to reach it. By the time you get a lock and the missile is fired, the Blackbird has already put quite some distance on you. You need to remember that it flies at 80-100,000 feet in altitude, so the missile will have to climb about 30-40,000 feet vertical just to be at the same level. Also, most air-air missiles have a top speed of Mach 3-4. Basically the missile won't catch up to it very fast, and it will run out of fuel before it ever does. I think the common stat that I've heard is that the Blackbird was fired at over 3,000 times, but was never hit.

  33. Re:What is the Speed of Sound? Its related to temp by homerito · · Score: 3, Informative


    The speed of sound in a gas is related to the temperature of the gas and the gas properties molecular weight and heat capacity (cp/cv).

    The relationship is:

    c = sqrt(j * R * T / M)

    where:
    c = speed of sound
    j = ratio of heat capacity (cp/cv)
    R = Universal gas constant
    T = Temperature (for gases always use absolute temperature)
    M = Molecular weight

    The Mach number is the ratio of the speed of an object over the speed of sound of the medium that the object is moving trough.

    The X-43A will be released at 40,000 ft and climb to 110,000. I am not very sure about the temperature at this altitude but I think is about -100 C or 173K. At that temperature speed of sound is:

    264 m/sec

    So Mach 10 would be:

    2640 m/sec or 5900 mph

    If X-43 could fly that fast lets say at, 1000 ft, mach 10 would be about 3400 m/s or 7600 mph. Unfortunately the air density at 1000 ft would not allow X-43 to go that fast.

  34. cool by zogger · · Score: 2, Interesting

    interesting pics, thanks. That's just a nasty cool looking little engine, isn't it?

    Tell ya WHUT though, along this whole thread on "this is the most advanced evar" and stuff, I wonder when they will finally admit to such things as aurora and brilliant buzzard and release some official pics and specs? I mean, the 117 and b2 are old hat now, and the sr 71 is so old it is medium retired, you can't tell me they don't have a few other models developed already.... smoke=fire usually

    1. Re:cool by Rei · · Score: 2, Interesting

      One of the beautiful things about this concept (combined gun/scramjet) is that if you engineer them properly, you don't need a single moving part, even a fuel pump. You can use air pressure to force the fuel into the combustion chamber, where it's pressurized enough and heated enough by the oncoming air that, like a diesel engine, it burns without needing a spark.

      Now, mind you, I don't know that's what they did here. And in fact, using air pressure to pressurize the fuel might prove to not be the best way to do it; still, it's an interesting concept that you could create a nonmechanical jet engine of almost any size that can operate at Mach 10, simply due to its shape. ;) If you're using hydrogen, you only need 1/4 of a rocket's propellant mass; if you're using, say, kerosene, you need somewhere around 28% of the propellant mass you'd need for an equivalent rocket. It'd really be an incredible boost either way.

      --
      That's it, Mr. Giraffe, get all the marmalade.
  35. Commercial Jets can do Mach 10 in a few years by dantheman82 · · Score: 2, Interesting

    Coat a commercial jet with plasma actuators (like a skin over the aircraft), and it will drastically reduce drag and a jet could feasible fly Mach 10 from California to Japan (or other global travel) and take minutes. Keep acceleration lower and it will not be noticeable to passengers. Here's a website that discusses this (I've also heard a presentation at Stevens Institute of Technology in Hoboken, NJ where this is being researched currently at a local company). http://www.poly.edu/glance/research.cfm?men=m11

    --
    This sig donated to Pater. Long live /.