Slashdot is powered by your submissions, so send in your scoop

 



Forgot your password?
typodupeerror
NASA Space Science

NASA Looks At Railgun-Like Rocket Launcher 231

Posted by CmdrTaco
from the spent-all-day-playing-ctf dept.
coondoggie writes "NASA is looking hard at a way to blast spacecraft horizontally down an electrified track or gas-powered sled and into space, hitting speeds of about Mach 10. The craft would then return and land on a runway by the launch site."
This discussion has been archived. No new comments can be posted.

NASA Looks At Railgun-Like Rocket Launcher

Comments Filter:
  • Well, this is not a (Score:3, Interesting)

    by ScrewMaster (602015) * on Tuesday September 14, 2010 @03:41PM (#33580002)
    new idea [imdb.com], exactly, but I guess it's good to see NASA looking at other possibilities. There are many. I remember MIT doing work on alternate launch technologies back in the seventies, if not earlier. The mass driver was one (a giant electromagnetic linear accelerator) although the idea was kicked around in science-fiction long before that. My current favorite is a possibly-reusable rocket whose reaction mass is water, using heat energy provided by ground-based lasers. You could launch things into orbit all day long with a setup like that. Probably need a dedicated nuclear power plant to run the thing.
    • by pilgrim23 (716938)
      http://www.youtube.com/watch?v=G3yN6WfpaUQ [youtube.com] its been done
      • Re: (Score:3, Informative)

        by timeOday (582209)
        Oh, it was already imagined in sci-fi novels and childrens' TV programs? Quick, somebody tell NASA before they waste a bunch of money developing a usable capability!
    • by PolygamousRanchKid (1290638) on Tuesday September 14, 2010 @03:49PM (#33580096)

      Well, I believe this critter was up and at it in the 70's at Princeton: http://en.wikipedia.org/wiki/Gerard_K._O'Neill [wikipedia.org]

    • by rjstanford (69735) on Tuesday September 14, 2010 @04:10PM (#33580350) Homepage Journal

      Ah, Heinlein, may you never cease to spin.

      Anyway, the other think to consider (especially for things like laser-based launches) is that the current "spit out a ton of speed really quickly and then coast your way to orbit" approach really sucks. Even a slow nice steady boost will get you to orbit without needing to hit escape velocity.

      • Re: (Score:3, Informative)

        by Nyeerrmm (940927)

        Who coasts into orbit? Once the engine cuts off in most any launch vehicle you've achieved orbit.

        Get going at the right speed from the ground and you'll enter orbit as long as there's not a mountain in the way (you'd probably want to boost your periagee afterwards though). The main reason you go up before accelerating to orbital velocity is that you get above the atmosphere and don't lose as much energy.

        • Depends on what engine and what launch vehicle you are talking about actually. Some of the larger, multi-stage vehicles will cut off the main booster or first stage before achieving a true orbit. This is usually followed by such a short coast that the primary cut-off doesn't matter. The rest of the launch vehicle will continue gaining altitude until ignition of the second stage. This isn't always the case, but, like I said, it depends on the vehicle and payload you are flying.
      • Re: (Score:3, Insightful)

        by ScrewMaster (602015) *

        Even a slow nice steady boost will get you to orbit without needing to hit escape velocity.

        Well, sure, you could do at a walking pace ... if you had the reaction mass.

      • by BlueStrat (756137) on Tuesday September 14, 2010 @04:58PM (#33581004)

        Ah, Heinlein, may you never cease to spin

        Yes, Heinlein used this tech as a centerpiece enabling technology for Moon->Earth grain shipments (and as a kinetic weapon used against Earth once the rebellion started..."throwing rice") from a lunar penal colony in his superb science fiction novel "The Moon Is A Harsh Mistress". I highly recommend the story. Heinlein was amazing at predicting tech & science advances far, far ahead of any of his contemporaries.

        In the above Heinlein novel, a rail launcher for Earth was proposed for several possible locations. These proposed locations shared certain characteristics, among them was elevation/altitude at the launcher exit point.

        NASA could do a lot worse than taking some more inspiration (IIRC he's generally credited with the concept of communications satellites) from such an intellect.

        Strat

        • by ScrewMaster (602015) * on Tuesday September 14, 2010 @05:09PM (#33581126)

          IIRC he's generally credited with the concept of communications satellites

          Nope. That was Arthur C. Clarke [lakdiva.org], another of the grand masters of hard science-fiction.

          • by BlueStrat (756137)

            IIRC he's generally credited with the concept of communications satellites

            Nope. That was Arthur C. Clarke [lakdiva.org], another of the grand masters of hard science-fiction.

            Ahh, right you are! Clarke and Heinlein are two of my favorite sci-fi authors. I really should have gotten that right. :/

            Strat

      • Re: (Score:3, Informative)

        "spit out a ton of speed really quickly and then coast your way to orbit" approach really sucks

        A "nice slow steady boost" will burn an enormous amount of fuel.

        Let's say your rocket weighs 1,000lb. If you provide = 1000lb of thrust your rocket will just sit there. If you provide 1001lb of thrust it'll start to accelerate every so slowly... if you provide 1002lb of thrust you'll accelerate twice as fast, but only burn ~0.1% more energy.

        You'll go faster (for a given thrust) as you burn up fuel and thus shed weight, but at any weight, the higher the thrust, the smaller the percentage of energy you spend just overcoming gravity, and the more you spend accelerating the vehicle.

        And don't forget, that if you got above the atmosphere "slow and steady"... if you're under orbit velocity, you're going to fall right down unless you plan on burning fuel forever.

      • by mdielmann (514750) on Tuesday September 14, 2010 @05:12PM (#33581146) Homepage Journal

        There are a number of reasons why rail guns are more attractive than a "steady boost".
        First, we don't have anything that gives a steady boost for any reasonable amount of time at a reasonable amount of force. Rockets just don't last very long in the overall scheme of things, and laser-based propulsion systems don't have enough force to launch any appreciable payload (yet).
        Second, rail guns don't require you to accelerate fuel in order to keep on accelerating. This puts an effective limit on rockets, and anything the rail gun adds pushes out our capacity based on the fuel limit.
        Third, the higher/faster you're going before you start using conventional rockets will reduce fuel requirements, increase payload, or increase orbit. This is somewhat related to the second item, but not entirely. Conventional rockets require you to bring your fuel with you, which reduces payload capacity, and this compounds with the effects of being deeper in the gravity well.

        • Re: (Score:3, Interesting)

          Yeah but going mach 10 at ground level isn't exactly rainbows and ponies either...
        • Re: (Score:3, Interesting)

          by dwinks616 (1536791)

          and laser-based propulsion systems don't have enough force to launch any appreciable payload (yet).

          And they never will. Lasers will NEVER be able to push anything into orbit, period. E=MC2. If you make E big enough to push a payload into orbit, your E ends up turning into M. Lasers only a bit more powerful than what we have now will end up creating matter in their pumping chambers and halting their output. The top few lasers on the planet are pretty close to the maximum power lasers can attain before spontaneously creating mass from the light they make. What may work, however is using a laser to be

      • by pclminion (145572)
        There is no such thing as "coasting into orbit." When the power cuts off, you are either in orbit or you aren't. When there is no thrust, your kinematic state is determined for all time -- you're purely under the laws of freefall mechanics. If you're not in orbit when the engines cut, you'll either hit the ground or escape the gravity well. There's no transitional period -- if there were, what forces would be acting to cause the transition? Gravity is a conservative force.
      • Bad Physics (Score:3, Informative)

        by sjbe (173966)

        Anyway, the other think to consider (especially for things like laser-based launches) is that the current "spit out a ton of speed really quickly and then coast your way to orbit" approach really sucks.

        Why on earth was this moderated interesting? Is wrong information interesting now? You can't coast to orbit. When the power shuts off you either are in orbit or you aren't. Gravity doesn't take a holiday just because you are out of propellant.

        Even a slow nice steady boost will get you to orbit without needing to hit escape velocity.

        You can't get into orbit without hitting escape speed (escape velocity is actually a misleading term because it is a scalar). Escape speed doesn't have to be fast (in fact it can be any speed) but again, once the engines shut off you had better be at the escape sp

  • "...hitting speeds of about Mach 10."

    "Starr noted that electric tracks catapult rollercoaster riders daily at theme parks. But those tracks call for speeds of 60 mph -- enough to thrill riders, but not nearly fast enough to launch something into space. The launcher would need to reach at least 10 times that speed over the course of two miles in Starr's proposal."

    Mach 10 = 600mph ???

    • Perhaps it only needs to get up to 600 MPH before the Scramjet takes over.

      If you read any of the articles on their scramjet tests, they need supersonic airflow to create the pressure inside the engine. Once ignited, Mach 10 wouldn't be outrageous for a Scramjet.

      http://www.shortnews.com/start.cfm?id=63070 [shortnews.com]

      Unfortunately escape velocity isn't Mach 10, but for early test platforms, we already have the tech necessary to do what's in the proposal, and what we might learn from repeated launches and fine tuning the

      • by durrr (1316311)
        http://en.wikipedia.org/wiki/Scramjet#Theory [wikipedia.org]
        Scramjets don't need supersonic airflow, they only need a dynamic pressure that is in the right interval. If you look at the equation in the wiki link you'll see that it will be able to operate at lower speeds at lower altitude, in fact, it will not be able to operate at mach 10 at low altitude at all, but would constantly speed up as it gains altitude to keep an approximately constant dynamic pressure.
        Seems elegant enough for me.

        And the scramjet would only b
      • by vlm (69642) on Tuesday September 14, 2010 @04:32PM (#33580662)

        Once ignited, Mach 10 wouldn't be outrageous for a Scramjet.

        Well, that seems a bit optimistic for a device that has been successfully flown, what, twice? Its kind of like planning the Boeing 777 the day after the wright brothers first flight.

        The real killer with all these "hybrid" lifter designs is they are all ignorant of the virtually unknown 666 rule.

        The 666 rule is that Mach 6 (which is tricky for an air breathing aircraft) at 60000 feet (again, tricky) is a whopping 6% of the way to orbit.

        So, if, in your wildest dreams, you can simultaneously achieve mach 6 at 60Kft, which would be quite the noteworthy achievement, you've still got 94% of the way to go.

        Alternately, you could take the required second stage, and make the fuel tank at least 6% bigger and skip all this air breathing foolishness.

      • by bcmm (768152)

        Perhaps it only needs to get up to 600 MPH before the Scramjet takes over.

        Well, unless something is taking over, this is just a big artillery piece: escape velocity is rather higher than mach 10 [wolframalpha.com].

    • The launcher would need to reach at least 10 times that speed

      "At least"....for all those times when you can't quite do the math!

    • by Prune (557140)
      The author probably rounded down to 100 times the speed and dropped a zero, possibly as a typo. It's the only plausible explanation I could come up with for this error.
    • by X0563511 (793323)

      Only at a ridiculously low pressure...

      (mach is dependent on the speed of sound, which is dependent on the atmospheric temperature and pressure)

    • by ratboy666 (104074)

      Maybe just missing a "0" -- should be "100 times", but even that's low. Mach 10 is around 6600 mph "where the jets go" and 7700 at sea level.

      Of course, escape velocity is 25,000 mph (no friction from the air factored in), but (and I didn't read tfa) it seemed like they want to come back (maybe like a really big boomerang?), so I don't think it matters.

      Just for grins, if the thing is launched at a 45 degree angle, it should reach a maximum height of approximately 185 miles, and travel a distance of around 75

  • Railguns? Rocket launchers? Too much Quake I say.
  • by Just_Say_Duhhh (1318603) on Tuesday September 14, 2010 @03:51PM (#33580120)
    According to TFA, the sled will be "hitting speeds of about Mach 10." That's fast, but then the TFA says, "electric tracks catapult rollercoaster riders daily at theme parks. But those tracks call for speeds of 60 mph -- enough to thrill riders, but not nearly fast enough to launch something into space. The launcher would need to reach at least 10 times that speed"

    Sorry, but 10x roller coaster speeds isn't close to Mach 10.

    NASA is on to something interesting here. It would seem that MagLev [wikipedia.org] is required (no wheels can handle that speed), and it would be interesting to see what kind of acceleration they can get out of LIM's [wikipedia.org]. Rocket propulsion seems a waste in this application. It might help bullet-train technology, and we can get some new spin-off inventions from NASA.

    • by mangu (126918)

      Sorry, but 10x roller coaster speeds isn't close to Mach 10.

      And even Mach 10 isn't enough, orbital velocity is close to Mach 25. You cannot run at that speed inside the atmosphere, there's no material that could withstand the heat.

      I've seen a much better idea proposed. Put that electric accelerator track in orbit. The energy needed to reach orbital altitude is much less than the energy needed to accelerate to orbital speed.

      One could launch the spacecraft vertically to an interception with the accelerator tr

      • TFA suggests that the Mach 10 will be to get some scramjets online, which will then boost to high atmosphere, and then pop out a small second (third?) stage rocket.

      • But when you catch the "track" to gain orbital velocity, wouldn't that just decay the track's orbit? You'd have to keep adding energy to the "track." I thought the rail gun concept was trying to avoid having to generate all that energy in space (thereby avoiding the need to launch all that extra weight)?
        • by mangu (126918)

          But when you catch the "track" to gain orbital velocity, wouldn't that just decay the track's orbit?

          Sure, but you would also use the track to decelerate spacecraft from orbital velocity to land on earth, which would cause the track to gain velocity.

      • by X0563511 (793323) on Tuesday September 14, 2010 @04:26PM (#33580580) Homepage Journal

        ... in which case Newton's Laws would adequately describe the reasons why your ultra-expensive orbital mass driver is now an ultra-expensive meteor shower.

        • by X0563511 (793323)

          (realized i should explain for those that don't get it)

          The force applied to the craft by the accelerator will also act against the accelerator. Firing the right way, it would drop the accelerator right out of orbit (it would impart it's velocity into the craft, leaving it with less than needed to maintain orbit, crashing down). Fired the other direction, and the exact reverse would be seen - the accelerator would "push" off of the craft, accelerating and gaining altitude, but the craft would then fall quite

          • OK, so it's a one-time use accelerator, but it's still good, nay?

          • by Somegeek (624100)

            How does something going 7 km/sec catch something going zero?

            Colliding, I can see. Gently catching and accelerating up to the same speed, I don't see.

      • Well that might defeat the purpose of such a system. The whole idea behind rail launching anything is to make launches cheaper and simpler. Having to use a rocket stage, to get to low orbit, to rendezvous with an orbital track, to propel a vehicle to its intended orbit probably doesn't match either of those criteria. Besides, the assumption that we would be launching from a track surrounded by atmosphere is pretty unimaginative. The way I see something like this working would involve building more of a tube
        • by mangu (126918)

          The problem with your idea is that the mouth of the tube should be open, otherwise how would the spacecraft come out? To be open it should need to be in a vacuum, otherwise air would come rushing in. You would need a tube extending all the way to above the atmosphere, let's say a hundred kilometers up.

          An awesome concept, but not simple or cheap.

      • by BitZtream (692029)

        And even Mach 10 isn't enough, orbital velocity is close to Mach 25.

        At what distance from the Earth?

        Orbital velocity is entirely dependent on your distance from the gravitational source and its gravitational pull.

        You already have 'some' orbital velocity just standing on the planet, in fact, you have enough to orbit if you go far enough away from the planet, though it wouldn't probably last very long.

    • by Fnord666 (889225)

      According to TFA, the sled will be "hitting speeds of about Mach 10." That's fast, but then the TFA says, "electric tracks catapult rollercoaster riders daily at theme parks. But those tracks call for speeds of 60 mph -- enough to thrill riders, but not nearly fast enough to launch something into space. The launcher would need to reach at least 10 times that speed"

      Sorry, but 10x roller coaster speeds isn't close to Mach 10.

      I think he is looking for more like 128x. Furthermore TFA calls for reaching th

      • Re: (Score:2, Informative)

        by amh131 (126681)

        Back of the envelope for 6000 mi/hr (100 x 60 mph rollercoaster) in 2 miles gives something on the order of 114 G.

    • by jdgeorge (18767)

      You're expecting a particularly informed, insightful article about rocket science in NetworkWorld? Seriously?

    • Re: (Score:2, Interesting)

      by movrev (1901148)
      Accelerating up to supersonic speeds on a maglev track is quite problematic from a controls/stability perspective. The generated shock waves will bounce off of the ground/track creating some interesting ground effects which will mess up the launch unless properly controlled. I'm sure their proposal is to get the sled up to about Mach 1, at which point they'll be able to take off with a ramjet engine. Once they reach around Mach 5 in the atmosphere, they could transition into a scramjet configuration which c
    • by ISoldat53 (977164)
      It's all that metric to inches stuff NASA can't seem to get right.
    • by BitZtream (692029)

      LIMs are 'theoretically' unlimited, you just have to space them out properly and sequence them fast enough. In practice of course, its entirely different. I think for most practical purposes of terrestrial motion, they will be practically unlimited until we invent inertial dampeners of some sort.

    • Re: (Score:2, Informative)

      by Athanasius (306480)

      This is really just bad wording in his opening paragraph.
      Really it's that:

      1. 1) The railgun part needs to get things up to 600mph, 10x the rollercoaster speed.
      2. 2) Once launched at 600mph off the railgun the scramjet fires up and eventually gets the thing to 'Mach 10'

      The Universe Today article is worded a little better: http://www.universetoday.com/73536/nasa-considering-rail-gun-launch-system-to-the-stars/ [universetoday.com]

  • Hey, it looks like someone read that Net [bussjaeger.org] Assets [smashwords.com] novel by one Carl Bussjaeger but decided that the trick could be done without using the libertarian sauce Bussjaeger pours over it. Bussjaeger ended up deciding that a rail gun or other tracked thing would not work so he went with a supersonic ground effect launcher.

  • Finally... (Score:4, Insightful)

    by Prune (557140) on Tuesday September 14, 2010 @04:03PM (#33580256)
    After all the hype that we've been hearing over the years about rail-guns and seeing a few military and hobbyist demos on video sites, this one piece of near-former sci-fi may be finally coming to fruition as a usable approach. It's a great example of the sort of thing that had to wait for technological improvements and refinements, rather than a fundamental scientific or technological breakthrough, and is the convergence of several technologies. I'm encouraged to see more progress on such things which seems to have in recent years been eclipsed by information technology's faster cycles and overhyping in media (and I say this as someone who makes his living as a software engineer).
    • After all the hype that we've been hearing over the years about rail-guns and seeing a few military and hobbyist demos on video sites, this one piece of near-former sci-fi may be finally coming to fruition as a usable approach. It's a great example of the sort of thing that had to wait for technological improvements and refinements, rather than a fundamental scientific or technological breakthrough, and is the convergence of several technologies. I'm encouraged to see more progress on such things which seems to have in recent years been eclipsed by information technology's faster cycles and overhyping in media (and I say this as someone who makes his living as a software engineer).

      I, well, I agree. And make my living the same way. I've also been a science-fiction fan since I was a kid (Clarke, Heinlein, Norton, Silverberg, Harrison, Dick, you name it I probably read it) and honestly I've been disappointed by the past forty years, at least so far as near-space development is concerned. I thought, well, I'd hoped we would be way further along than we are, and had we continued the pace of development after the end of the Apollo program we would have be. But we chickened out, let our lea

    • Re: (Score:3, Interesting)

      by DerekLyons (302214)

      After all the hype that we've been hearing over the years about rail-guns and seeing a few military and hobbyist demos on video sites, this one piece of near-former sci-fi may be finally coming to fruition as a usable approach.

      Nope, this piece of "near former sci-fi" is just as far from fruition as it ever was.

      It's a great example of the sort of thing that had to wait for technological improvements and refinements, rather than a fundamental scientific or technological breakthrough, and is the conver

      • by Jeremi (14640)

        The basic problem with a railgun is that it give only a fraction of the velocity required - and it does so only in one plane.

        Maybe I'm missing something, but can't you point the railgun in any direction you want? Granted it's probably cheaper to run the track along the ground, but you could at least in principle aim it straight up, or diagonally, or any other direction...

        Incidentally, I suspect the appeal of the railgun is similar to the appeal of a Space Elevator... if you can supply the fuel/energy from

    • Then after the professor trots the dancing girls out of the giant bullet-capsule the moon will grimace and wince as the bullet-capsule will be stuck in one of his eyes.
  • Oh the acceleration! Hopefully this is not for manned flights!

  • One faster (Score:2, Funny)

    by Anonymous Coward

    Well you could you know, make it one faster, you know go up to Mach eleven. Well, it's one faster, isn't it? It's not ten. You see, the Russians, you know, will be launching at Mach ten. You're on Mach ten here, all the way up, all the way up, all the way up, you're on Mach ten on your magnetic sled. Where can you go from there? Where? Nowhere. Exactly. What we do is, if we need that extra push over the cliff, you know what we do? Mach Eleven. Exactly. One faster.

  • built alongside the crawlerway? Just when I thought real estate prices in the Space Coast of Florida couldn't drop any lower, now we have sonic booms being generated at ground level just a couple miles from Merritt Island and Cocoa Beach.

    In related news, I just opened "Space Coast Window Repair."

  • So, the rail takes the x-43-like launcher to 600 (10x60) mph? That's not nearly enough to ignite the engine. Assuming it gets 5 times as fast (3000 mph should be enough to ignite it) it will be very close to the ground. 3000 mph close to the ground must generate non-trivial amounts of heat (and broken windows). Ignore that (because the launcher appears to have SR-71-like engines) for a moment and imagine the launcher now has to propel itself to the upper atmosphere, where it reaches Mach 10 (something we ne

  • I have no idea how heavy the Shuttles (or Soyuz capsules for that matter!) are even without the massive fuel tanks/rockets but I imagine this will take a lot of energy to get the job done.

    I think it's a great project for two main reasons:
    1. Figure out how to generate and store a big chunk of energy.
    2. Use it to accelerate and object to escape velocity.

    There is so much potential for discovery in both areas it boggles the mind.

  • fast enough to kill a human. I may be mistaken, but I am pretty sure that is the case. Current fighter pilots reach speeds high enough to black out (and/or red out). At said speed, they can't reach orbit. I can see no way for us to create a purely (or even mostly) land based launch system to supply enough energy in a short period of time to reach escape velocity. Not even if you built it on the Tibetan plateau that reaches 5000 meters above sea level.

    To keep the human alive, we need a slower, lon

    • by tibit (1762298)

      You black out when you fly a curved path -- that's the only way to generate sufficient accelerations. To merely fly fast, all you've got is the mass of the aircraft (and your butt) counteracted by the engine thrust. Gives a nice buttkick, but not nearly enough to cause any distress.

      The fighter pilots black out when they make turns, and for that they don't need to fly fast at all. You can easily black out on an aerobatic biplane with a prop engine.

    • SPEED doesn't kill you, acceleration might. Bear in mind you are currently moving at at least 1000 MPH.

  • If NASA starts looking at alternatives, I'd be interested in what they say about Launch loops [wikipedia.org]. They always looked cool to me. Maybe one day NASA will look at those also?
  • Why at sea level? (Score:2, Insightful)

    by Anonymous Coward

    Why would they do this at sea level? This should be done somewhere in the American West, at altitude. At 10K feet there is a heck of a lot less air resistance. Could be done on one of the Air Force ranges for sonic boom sake.

    • by istartedi (132515)

      I was thinking this too. Edwards AFB maybe? Hmmm... only about 2500 ft apparently. We can get to 5000 feet easily on a lot of places out west though, and I'm sure the military already controls a lot of flat land at that altitude or greater. 10000? I don't think you can do that without the extra hassle of building on very steep land.

  • I'm a complete layman here, but it seems to me that friction from air would be a serious problem at the speeds a vehicle would have to be propelled off this launcher. By the time conventional rockets have achieved a significant speed they're already fairly high in the atmosphere. I can't see a launch tower being practically ramped up high enough to overcome these effects. The vehicle would have to survive the stresses of heat and friction at launch and reentry. There's also the matter of drag kicking in bef

    • This sounds comparable to firing a bullet from a gun which seems like it would be a rather violent launch.

      Depends. If you used a linear accelerator (e.g. a mass driver) of sufficient length, you could accelerate at one G. You'd probably want more than that, though, to keep the size of the launcher manageable.

  • I guess it's Back to the Future...or is that Past...

  • "Emerging Technologies May Fuel Revolutionary Launcher" [nasa.gov]

    It looks more like the rail truck accelerates the launch vehicle to mach 1 which leaves the end of the track and the scramjet lights and carries it and its payload to mach 10 at about 20 miles altitude. The payload then separates from the launcher, the rocket ignites and sends the payload into orbit. The launch vehicle returns and lands for reuse.

    This sounds a lot more feasible than a mach 10 rail gun!

  • I agree that this idea has been around a while -- it's still a great idea.

    Scramjets are really pretty simple devices compared to rocket engines. This machine would be like the first and second stages of a three-stage rocket, saving something like 80% of the mass. (OK, most of that mass is relatively cheap kerosene and LOX, but still.) Getting a sled up to Mach 1 to get the scramjets started is really not that challenging. If they don't start correctly, you just slow down ... and nothing bad happens.

    One

  • by Somegeek (624100) on Tuesday September 14, 2010 @06:01PM (#33581700)

    Everyone is banging their head over trying to hit Mach 10 on the track.

    TFS and everyone else is misunderstanding the proposal.

    The current idea is for the sled on the track to accelerate a scramjet up to about 600mph, then the scramjet lifts off, flies up to altitude and at about mach 10, releases a rocket which boosts the payload into orbit.

    Sled (reusable) on the ground = 1st Stage
    Scramjet (reusable) in the atmosphere = 2nd Stage
    Booster Rocket in space = 3rd Stage

    All extensions of more or less current technology.

I've got all the money I'll ever need if I die by 4 o'clock. -- Henny Youngman

Working...