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Space

NASA to Attempt Mach 10 Flight Next Week 357

Posted by CmdrTaco from the hello-john-val-says-hi dept.
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."
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NASA to Attempt Mach 10 Flight Next Week More

NASA to Attempt Mach 10 Flight Next Week

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  • What is the Speed of Sound? (Score:5, Insightful)

    by Anonymous Coward on Thursday November 11, 2004 @05:12PM (#10791949)
    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?

    • Re:What is the Speed of Sound? (Score:2, Funny)

      by Anonymous Coward
      Speed of sound in a vacuum?

      Just a guess. ;)

    • Re:What is the Speed of Sound? (Score:4, Informative)

      by kuwan ( 443684 ) on Thursday November 11, 2004 @05:25PM (#10792127) Homepage
      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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      • That's not really a speed record, considering the space shuttle hits, what, around 22,000 miles per hour?

        • Rockets vs. Jet Engines (Score:5, Insightful)

          by hey! ( 33014 ) on Thursday November 11, 2004 @05:59PM (#10792492) Homepage Journal
          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.

        • Re:What is the Speed of Sound? (Score:5, Informative)

          by bleckywelcky ( 518520 ) on Thursday November 11, 2004 @06:01PM (#10792517)
          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.

        • Re:What is the Speed of Sound? (Score:5, Informative)

          by kuwan ( 443684 ) on Thursday November 11, 2004 @06:05PM (#10792575) Homepage
          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: [physorg.com]
          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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    • Re:What is the Speed of Sound? (Score:4, Funny)

      by quizwedge ( 324481 ) on Thursday November 11, 2004 @05:27PM (#10792156)
      In Space... No One Can Hear You Scream
    • "Mach" is specifically intentionally referenced to the speed of sound. IAMAAE (aviation engineer), but most obviously, sonic booms always appear as soon as the aircraft goes as fast as the speed of sound, and this speed changes depending on the temperature and makeup of the medium that the object is travelling in. I presume there are other aerodynamic properties correlated with the Mach number as well (for instance, see references to the "Mach cone").

      • Re:What is the Speed of Sound? (Score:5, Interesting)

        by ab762 ( 138582 ) on Thursday November 11, 2004 @06:01PM (#10792521) Homepage

        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 [aerospaceweb.org] on this Frequently Asked Question.

      • Re:What is the Speed of Sound? (Score:2, Interesting)

        by Anonymous Coward
        "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 no
    • 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
    • All discussion of physics aside, your description of how the craft works is incorrect. The scramjet is only turned on once, and it is most certainly within the atmosphere when that happens, otherwise the scramjet wouldn't work.

      The "skip-glide" mode of flight you describe has been proposed [space.com] but never demonstrated.
    • It's burning fuel with incoming air (that's the "ramjet" part of "supersonic combustion ramjet". So you know it's flying where there's still a usable amount of atmosphere. The Mach number is the ratio of vehicle airspeed to speed of sound in the air around the vehicle -- it's the number that controls the shape of the shock wave and other important aerodynamic properties.

    • The speed of sound in a vacuum is Zero. Sound has to have air to propogate. Hence the saying "In Space no one can hear you Scream". Mach 10 is pretty fast but I seem to recall some Aussies who broke Mach 15 with a very small scale Scamjet mounted on a rocket to give it the intial boost. The name HyShot? HighShot? seems to be what I recall. I don't have time to Google it.

    • Re:What is the Speed of Sound? (Score:5, Informative)

      by AyeRoxor! ( 471669 ) on Thursday November 11, 2004 @06:45PM (#10792986) Journal
      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 [google.com], 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 [google.com]. Sheesh.

      At Mach 10, you will circle the Earth [lyberty.com] in under 200 minutes [google.com].

      Damn I love Google math.


    • 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
    • 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 spee

    • Re:What is the Speed of Sound? (Score:5, Informative)

      by Jetson ( 176002 ) on Friday November 12, 2004 @02:38AM (#10795886) Homepage
      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.

  • Risky? (Score:2, Funny)

    by MycroftMkIV ( 197922 )
    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
    • The thing falling and crashing into another thing risky. The thing exploding on launch, blowing up the B-52 with people on it risky. I dunno, take your pick.

  • W00T! (Score:3, Funny)

    by Anonymous Coward on Thursday November 11, 2004 @05:14PM (#10791979)
    Now they can hurtle spacecraft towards Mars even faster before they malfunction and drift into outer space :D
    • For a minute there, I read that as NASCAR. Dear lord, all we need are hicks going that fast. They can't even keep the cars from crashing, how are they supposed to stop and stay alive? Wait... that's the secret.. never mind! Move along, nothing to see here!

  • Flying faster than a first post... (Score:2, Funny)

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

  • To Bad for the sonic Boom. (Score:5, Interesting)

    by jellomizer ( 103300 ) * on Thursday November 11, 2004 @05:18PM (#10792044)
    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.
    • 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?

    • Re:To Bad for the sonic Boom. (Score:5, Informative)

      by Cheeko ( 165493 ) on Thursday November 11, 2004 @05:33PM (#10792200) Homepage Journal
      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.
      • Actually, any form of combat would be nearly impossible at mach 10. Even with the pilot pulling 10 G's, your turning radius would be half a continent wide. Most dogfights occur at subsonic speeds. We will have to invent Star Trek's intertial dampeners. Look how bad the patriot missiles were at hitting a missile moving mach 4.

        You can't do any low altitude flight either, because the denser air would quickly melt and tear apart the aircraft at those speeds. What this is great for, is a potentially cheape

      • Re:To Bad for the sonic Boom. (Score:2, Interesting)

        by Anonymous Coward
        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 [fas.org] 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. [globalsecurity.org]

        The U.
    • Yeah, we can already fly faster than their planes. Soon, though, we might be able to fly faster than their missiles. For that matter, we'll be able to fly faster than their bullets. Consider that the railguns the US is planning for its frigates have a muzzle velocity of mach 7.5. I think going mach 10 could come in real handy.
    • The concorde [wikipedia.org] solved this by reaching mach speeds over the ocean. That is not why it failed. It failed because of the costs and lack of a significant market. I for one wouldn't mind saving $10,000 for spending an extra 10 hours on a plane.
      • Actually, it never failed. Once British Airways purchased the aircraft from the British - French consortium (for the grand sum of £1 per plane :), they started making profit on the flights. Interesting anecdote: When British Airways took over the planes, they looked for ways to make them profitable. They threw a party for all the most frequent fliers of Concorde, and at that party, they had people go around the fliers and ask them how they valued their seats on the plane. THey found out that 90%
        • The Olympus turbofans were some of the most powerful ones ever produced, that saw use outside of the space shuttle and such. (Yes, I'm aware the space shuttle doesn't use turbofans...but it's the same idea.)

          Imagine if they mounted those engines on a fighter or something.
        • Interesting piece of trivia:

          The Concorde's Olympus engines put out more thrust (169 kN beak) than Project Pluto [wikipedia.org]'s nuclear powered ramjet did (156 kN peak)

          Hah.
    • 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

    • 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 [tiscali.co.uk] but still be able to timely reach some of the theaters, where expensive and uncomfortable carriers have to be u

  • One step closer to (Score:4, Funny)

    by jaguar5150 ( 822144 ) on Thursday November 11, 2004 @05:18PM (#10792054)
    Ludicrous Speed!

  • Practical application (Score:3, Funny)

    by darco ( 514434 ) on Thursday November 11, 2004 @05:19PM (#10792056) Homepage Journal
    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)

    • Re:Practical application (Score:4, Insightful)

      by trybywrench ( 584843 ) on Thursday November 11, 2004 @05:27PM (#10792152)
      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.
      • So, where would you keep all the fuel? Scramjets can produce a lot of thrust, and they can sustain very high speeds, but they are not efficient. The whole point of a cruise missile is that it cruises, that is to say it operates at very efficient speeds for maximum range.

        Scramjets are less efficient than ramjets, much less efficient than turbojets, and way, way less efficient that the turbofans used in the longest-range cruise missiles and civilian aircraft. And what's worse is, you need some other form

    • Rocket fule weighs 17 times as much as as jet fule per unit energy due to the need for osidiser. So you could build a craft that carried a rocket up to mach 10 then have it shoot into space and the rocet would need a lot less fule so it would weigh less so your scramjet would not need as much fule to lift it ect. You end up with a lot of fule savings and jet's tend to be safer than rockets which also helps.

      Basicly an air breathing craft that can hit mach 10 would make a great 1st stage for a space craft.
      • Basically an air breathing craft that can hit mach 10 would make a great 1st stage for a spacecraft.

        Rocket fuel weighs 17 times as much as jet fuel per unit energy due to the need for oxidizer. So you could build a craft that carried a rocket up to mach 10 then have it shoot into space and the rocket would need a lot less fuel so it would weigh less so your scramjet would not need as much fuel to lift it ect. You end up with a lot of fuel savings and jets tend to be safer than rockets, which also helps

  • Comment removed (Score:3, Insightful)

    by account_deleted ( 4530225 ) on Thursday November 11, 2004 @05:19PM (#10792069)
    Comment removed based on user account deletion
    • 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 [aviationnow.com].

      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.

  • The B-52 (Score:4, Insightful)

    by OverlordQ ( 264228 ) on Thursday November 11, 2004 @05:20PM (#10792084) Journal
    The B-52, the American workhorse for over 50 years. So called 'Weapons of War' can be used for other, good purposes, like this.
  • 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.
    • Except LEO is about 17,000 MPH, and this thing can only go about 7200. And a scramjet doesn't work until you're already going supersonic speeds.

      So what you'd need for this craft is a jet engine or rocket to get you fast enough for the scramjet to kick in, which would then get you to 7,000 MPH, when a rocket has to kick in to get you the other 10,000 MPH and out of the atmosphere.

      Basically such a craft would have to carry a regular jet engine, a scramjet, and a rocket, Or perhaps just a scramjet and a liqu

  • Perfect cycle (Score:4, Funny)

    by IGnatius T Foobar ( 4328 ) on Thursday November 11, 2004 @05:30PM (#10792174) Homepage Journal
    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!
  • "Watch out for that treeeeeeee....!"
    • -or-

    "We can rebuild him. Make him better."

    "Better?"

    "Better, stronger .... faster!

    Cchhcchhhooonnnggooonnnggooonnnggooonnngg.

  • Stanley Spadowski: George, you know I was wondering, like if you were traveling through outer space, I mean like you're going real fast, like the speed of light, you know ...hoooohhhhh... and all of a sudden you started screaming ...aaaahhhhh aaaaahhhhh... Do you think your brain would blow up?

    Bob: Guys, I'm trying to work... Do you mind?

    Stanley Spadowski: I don't mind. Go right ahead... Do you mind, George?

  • Final Flight (Score:5, Interesting)

    by SimURL ( 822939 ) on Thursday November 11, 2004 @05:36PM (#10792239) Homepage
    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 [wired.com],
    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.

  • Blackbird and the Swedish fighter Viggen (Score:5, Interesting)

    by 3770 ( 560838 ) on Thursday November 11, 2004 @05:50PM (#10792393) Homepage
    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.
  • Don't forget the Delta IV heavy launch, whose latest postponement has it lifting off on Nov 18. This should be the most powerful rocket to lift off from the area of land between Bermuda and Hawaii since the 70's. It's supposed to be able to hurl 48,000 lbs of payload to low Earth orbit, almost 1/4 the capacity of the Saturn V. What an accomplishment.

  • Here is another interesting propulsion design. Anyone have any insight into this technology. Glow Discharge Plasma [jnaudin.free.fr]. Does this technology have promise? How about for space travel? Obviously a scramjet needs oxygen which makes space travel a little difficult.
  • Miscellaneous anti-filter crap.
  • MINE goes up to eleven.
  • Can someone explain to me how this 12-foot "Aircraft" is not referred to as a rocket? I'm just curious how you draw these lines of definition.
    • 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 reactio

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

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