back to article DARPA: You didn't think we could make a Mach 6 spaceplane, so let us have this MACH TEN job

In this post-Space Shuttle world, it often seems that the dream of a spacecraft which could reach orbit without expensively throwing most of itself away is receding rather than drawing closer. Last time DARPA went for a spaceplane - the X-30 SSTO concept of 1984 Sure, there's the tiny X-37B "space warplane", carrying out …


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  1. Tom 7 Silver badge

    I still think a rail/supergun in the Andes is the best bet

    for launching non human things into orbit.

    They'd have to be stuck on a scramjet/rocket stack to do the last bit but the first bit can be quite low tech and so cheap.

    1. James Hughes 1

      Re: I still think a rail/supergun in the Andes is the best bet

      Muzzle velocity would have to be so high, even with a booster (air drag, even in the Andes is pretty high), to make orbit, that I think the payload would vapourise.

      May as well just use a rocket booster to get up to scramjet speed.

      1. Tom 7 Silver badge

        payload would vapourise???

        Wouldn't it normally then?

    2. Gary Bickford

      Re: I still think a rail/supergun in the Andes is the best bet

      Not a rail gun per se, but a magnetic launcher (aka 'coilgun') has potential. These are the key factors:

      1) The advantages are in potential launch frequency and cost, which is mostly related to fuel and not having to throw away hardware.

      2) don't try to do the entire launch package from the railgun, use it as the first stage replacement.

      3) without a lightweight heat shield, you are limited in the maximum speed until you get most of the way out of the atmosphere to avoid burning up. But even getting to mach 5 (3800 mph, 1.7km/s) saves about half the fuel. It's been said that 50% of the fuel is used getting to the first 100 feet off the launch pad.

      4) if you want humans on board, it's going to be a very long coilgun. I ran similar numbers a couple of months ago - at 10G to reach 5km/s would require a 12.5 km coilgun and 50 seconds. That's beyond what most humans can take, but would be fine for most cargo. I'm too lazy to redo the numbers for 5G and 2km/s but using thumbnail math, 5G to 2.5km/s would also be 12.5 km but 100 seconds?

      5) don't forget the mass and handling of the 'carriage' - the thing that the vehicle rides on going up the launcher - you don't want to launch that

      The bottom line is, if you look at the coil gun as a cost saving system (long term), it could work. And Ecuador actually does have a space program, so there's an opportunity for someone to work out a deal. Having such a launch system right on the Equator is certainly advantageous. I would think that such a launch system would cost a few $billion.

      1. Mark York 3 Silver badge

        Re: I still think a rail/supergun in the Andes is the best bet

        Point 5 - Unlike the Fireball XL5 carriage that happily flies off into destruction @ 56seconds in & hopefully with less wobble too as it travels down the track.

        Esc (Velocity) Key. :D

      2. Anonymous Coward
        Anonymous Coward

        50% of the fuel for the first 100 feet off the launch pad?

        Maybe "it's been said", but that is crazy on the face of it. Think how fast the typical rocket is moving when it reaches the 100 foot mark, and explain why you would believe such a wild assertion when you're only traveling a fraction of the speed you need to reach after only 100 feet. If this was the case, rather than lift all that extra fuel off the pad for only 100 feet, they'd have the rocket connected with a breakaway hose to supply it and make the first stage half as large or use that reduced weight to massively increase the lifting capacity!

        Disclaimer: I'm not a rocket scientist, but I'm able to recognize off-by-at-least-a-factor-of-ten errors in logic when I see them.

  2. Trevor_Pott Gold badge

    Tried this one already. Lost the Kerbal. Spaceplanes not so good for getting payloads into orbit. Maybe I need a new mod?

    1. Anonymous Coward
      Anonymous Coward

      MechJeb's attitude hold makes achieving orbit much easier, but the fuel margins are so tight you can use space planes for hauling kerbals and not a lot else.

      That said, taking one from the runway, refuelling at an orbiting station and then landing back* on the runway is seriously satisfying.

      * Or, you know, crashing on the runway.

    2. Anonymous Coward
      Anonymous Coward

      SSTO Spaceplanes aren't too hard to get into orbit in KSP (hint: smaller planes are vastly easier to use)... but their payload fraction is so small that they're not much use for anything other than ferrying crew. They don't scale very well, either. It is one of the ways in which KSP is rather like real life, in fact.

  3. Parax
    Thumb Up

    Grasshopper: it has not shown that the launch stack can spare enough fuel for this to happen

    We shall soon see.. the next Falcon 9 Launch is the full size stack (60% larger than the current dragon launchers) it's using the octoweb engine configuration and it'll attempt a soft landing over water.. (which may or may not work depending on the radars ability to see water, as it's designed for land)

    This is the first step in combining grasshopper into a real rocket. There are still many things that could go awry in just the rocket nevermind the soft landing. But its an awesome system nonetheless.

    It's currently sat on the launch pad at Vandenburg afb, and is due to launch very soon (in days).

    1. James Hughes 1

      Re: Grasshopper: it has not shown that the launch stack can spare enough fuel for this to happen


      "So it might seem to many observers that the dream of re-usable, affordable access to space for the human race remains as far off as ever."

      Seems an odd statement to make , esp. as it follows the paragraph about the grasshopper, which to me seems a great step forward towards reusability.

  4. Pen-y-gors Silver badge

    Basic questions for DARPA projects

    1) Can we use it to kill people, preferably enemies (i.e. any foreigner)?

    2) Will it cost at least $1 billion for each person we kill with it?

    3) Will the cost be at least 100 times the amount of campaign contributions needed to get it approved?

    4) Could the money be better spent on more socially useful projects?

    If the answers to the above are all YES then go ahead and build it.

    ...I think I'm getting a wee bit cynical

    1. FartingHippo

      Re: Basic questions for DARPA projects

      Spoil sport.

      You'd have canned the whole CERN thing too, wouldn't you.

      1. Anonymous Coward
        Anonymous Coward

        Re: Basic questions for DARPA projects

        >You'd have canned the whole CERN thing too, wouldn't you

        I don't see the comparison between DARPA and CERN

        DARPA is military and top secret for the US only

        CERN is multinational, all discoveries are open to all.

        <goes back to my Higgs field ant-gravity space-plane research>

        1. Steve Todd

          Re: Basic questions for DARPA projects

          And yet there are research projects that started in DARPA that have changed the world (the Internet began life as ARPANET, when DARPA was called ARPA). Research is not a bad thing. What you do with the results can be.

      2. willi0000000

        Re: Basic questions for DARPA projects

        the US did cancel it's very own "CERN thing." it was the SSC in Waxahachee. 40TeV collider vs 14TeV for the LHC. could have been run at 1/3 power back in the late nineties and grabbed the Higgs then. all the talent and money that went to CERN could have stayed in the US for a few billion more. what will 10-15 more years of research into actually knowing what mass and inertia are, rather than just describing them, bring?

        the US government broke an unwritten agreement with the scientists when they canned that particular project. the agreement was that scientists would work like dogs for short money and the government would pay those salaries and pick up the cost of equipment. this type of thinking has done as much to cripple the US economy as sending all the manufacturing jobs overseas.

    2. JDX Gold badge

      Re: Basic questions for DARPA projects

      How much in the world of medicine has its roots in military R&D do you think?

      1. Natalie Gritpants Silver badge

        Re: Basic questions for DARPA projects

        To one decimal place of accuracy: 0.0%

      2. Pen-y-gors Silver badge

        Re: Basic questions for DARPA projects

        > How much in the world of medicine has its roots in military R&D do you think?

        Quite a lot I suspect, particularly the techniques dealing with the effects of injuries caused by all those clever gadgets developed by DARPA and the rest of the world's Merchants of Death (TM)

        1. MrXavia

          Re: Basic questions for DARPA projects

          "How much in the world of medicine has its roots in military R&D do you think"

          Actually plenty, especially in the world of trauma medicine, those skills are honed and refined on the battle field..

          Even vaccinations were often first tested with the military.

          Then we have the exciting limb replacement field of research, and I am sure that the fancy ultrasonic bleed stopper thingy they are working on will be a life saver for paramedics once they get it down to commercial cost.

          1. william 10

            Re: Basic questions for DARPA projects

            And I thought those skills where developed on the streets of our big cities, I understand that the US military train a lot of there surgeons by getting them to work in some the Big West cost hospitals (I suppose that is one advantage of america's policies on guns - well trained trauma surgeons).

            And here in the UK, a lot of our trauma care practises were developed in Northern Ireland by civilian hospitals.

            1. disgruntled yank Silver badge

              Re: Basic questions for DARPA projects

              I don't know where the military "train a lot of there" surgeons, but as for the battlefields, they train a lot of surgeons there, who later bring the techniques to big city trauma centers.

            2. John Smith 19 Gold badge

              Re: Basic questions for DARPA projects

              "And I thought those skills where developed on the streets of our big cities, I understand that the US military train a lot of there surgeons by getting them to work in some the Big West cost hospitals (I suppose that is one advantage of america's policies on guns - well trained trauma surgeons)."

              Actually quite a few of those techniques were developed on the streets of Belfast during "The Troubles," as the UK liked to call the low key civil war it fought for 38 years.

      3. Santa from Exeter

        Re: Basic questions for DARPA projects

        "How much in the world of medicine has its roots in military R&D do you think?"

        Reconstructive Plastic Surgery

        Pretty useful hey?

        1. Kubla Cant Silver badge

          Re: Basic questions for DARPA projects

          "How much in the world of medicine has its roots in military R&D do you think?"

          Reconstructive Plastic Surgery

          The military R&D contribution to Reconstructive Plastic Surgery consisted entirely in supplying horribly injured patients for surgeons to work on in civilian hospitals. So their contribution was not dissimilar to that made by Burke and Hare in an earlier era.

          1. Tom 7 Silver badge

            Re: Basic questions for DARPA projects

            Enabling by disabling!

      4. John Smith 19 Gold badge

        Re: Basic questions for DARPA projects

        "How much in the world of medicine has its roots in military R&D do you think?"

        Off the top of my head.

        Antibiotics WWII. Historically infection has killed many more wounded that the original injuries. They only started to become available to civilians after WWII.

        Surgical methods to operate on beating hearts (shrapnel wounds in WWII)

        Reconstructive surgery (Look up "The Guinea Pig Club," or watch parts of the film "Battle of Britain.")

        Improved amputation, antisepsis and prosthesis development. Every war.

        Use of cyanoacrylates to glue wounds together without stitches and reduce trauma. Vietnam.

        Direct injection to the heart through the breastbone. Vietnam.

        "Smart stretcher" technology to give better monitoring of patient conditions with fewer qualified staff..

        And IIRC developing ways to wash out living cells from things organs leaving a scaffold to act as a template for a patients own "precursor" cells to populate, eliminating rejection issues.

        That's just my 30secs of thought.

        You might be surprised. It's focused but significant

      5. No, I will not fix your computer

        Re: Basic questions for DARPA projects

        I always find it funny how military R&D is promoted as a positive thing because it has helped non military people......

        Think about this for a few seconds;

        Broad estimate, 150 million people killed in wars last century, and far more wounded, these wounded are the reason to get better at medicine, but how about, don't have war? all those people, all that lost potential, what could they have done? what if all of the people who lost limbs in the war didn't lose limbs? isn't prevention better than cure? is burning a house down a positive thing as it helps us learn how to put out fires?

        Yes, absolutely, through need, we learned so much more - but that's because so many died and suffered, imagine if we didn't pile the billions into killing people ($700bn a year for defence in the US), imagine what we could do instead, the education we could pay for, the infrastructure we could build - the rovers, the rockets - imagine if we stopped thinking "what can this kill" and started thinking "what could this tell us", yes war gives us developments, some of which have good spinoffs - so why not just look at the spinoffs.

      6. Destroy All Monsters Silver badge

        Re: Basic questions for DARPA projects

        > How much in the world of medicine has its roots in military R&D do you think?

        That's easy.

        Deduct the cost of actual wars, and I would guess about minus 3-4 trillion USD.

    3. John Smith 19 Gold badge

      Re: Basic questions for DARPA projects

      "1) Can we use it to kill people, preferably enemies (i.e. any foreigner)?"


      2) Will it cost at least $1 billion for each person we kill with it?


      The "Tactical Technology Office," of which this is part, may be a $Bn operation but individual DARPA projects are much smaller, 10s-100s of $m. The goal is High risk/High return. In fact very high risk.

      3) Will the cost be at least 100 times the amount of campaign contributions needed to get it approved?

      Wrong. This is more like an old Hollywood B picture operation. Fast turnaround, long shots, minimal costs.

      4) Could the money be better spent on more socially useful projects?"

      It's the DoD. They employ millions of staff and spend Trillions of $.

      What's not "socially useful" about that?

      Please stop hugging the tree and return to your lentils and brown rice.

  5. Frankee Llonnygog

    Simple solution

    A massive aircraft armed with a railgun launches a projectile that goes into scramjet mode that then launches a nuclear rocket which gets its final acceleration from an orbital laser.

    That's only 5 stages, but I'm sure we can think of more if we really try

    1. Ralph B

      Re: Simple solution

      You forgot to launch the massive aircraft from a helium balloon.

    2. James Hughes 1

      Re: Simple solution

      Don't forget the nuclear reactor required to generate the power for the railgun.

    3. Horridbloke

      Re: Simple solution

      The massive plane will probably need JATO to get off the ground.

      1. Frankee Llonnygog

        Re: Simple solution

        And it could be launched from a Captain Scarlet-style Cloudbase

      2. xehpuk

        Re: Simple solution

        And air fueling to reduce takeoff weight.

        1. Frankee Llonnygog

          Re: Simple solution

          Somehow we have to incorporate men who stare at goats

  6. cortland

    Once something become possible

    Once a thing is shown possible, feasible, and affordable, it is inevitable; who would have thought North Korea could build its own nukes?

    1. Trevor_Pott Gold badge

      Re: Once something become possible

      Building a nuke is easy. Building rockets is hard. Building space planes is dark fucking magic.

      Seriously. "North Korea built it's own nukes." Annnnnnnnnnnd?

      Basic nukes aren't hard. They require zero engineering experience (for a gun-type nuke.) Even a basic implosion device is simple, assuming you're okay with it being the size of a house. (The chances that these are miniaturized enough to fit on a missile are slim to none.)

      "Possible feasible and affordable" take a back seat to "comprehensible." An iPad is "possible, feasible and affordable." Yet, if you weren't allowed to do commerce with the rest of the world to buy one and didn't have knowledge of the past 50 years of intermediate technologies, that iPad simply isn't "comprehensible." It takes massive amounts of infrastructure, engineering and high-tech capability to make an ipad.

      It takes some C4, a couple slabs of U-235 rich(ish) uranium and some scrap metal to make a nuke.

      Wake me when North Korea can make an iPad using technologies it didn't have to steal. Then I'll believe that there is a chance of anyone but DARPA developing a SSTO spaceplane within our grandchildren's lifetimes.

      1. Scott Wheeler

        Re: Once something become possible

        > Basic nukes aren't hard. They require zero engineering experience (for a gun-type nuke.)

        Ok, that means you need U235. Do you know of an easy way to get that?

        Do you need an initiator for your design? What will you make it of, and how large is it?

        What is your critical mass? What amount of explosive do you need in the gun to avoid a squib explosion? Is there any danger of the explosive shattering the uranium that it is propelling?

        1. Robin Bradshaw

          Re: Once something become possible

          @Scott Wheeler, whilst this isnt a step by step DIY guide to making a nuke in your shed theres some interesting insights into building a plutonium implosion bomb here:

          Although I would dock them points for using a polonium-beryllium initiator (PoBe) a plutonium-beryllium initiator (PuBe) has much more scope for mirth and giggles.

          1. Pascal Monett Silver badge

            I believe that building a nuclear bomb is at least as difficult as building a space plane. I read somewhere that, even if you have the plans, you can still fail your design if you don't have someone with experience in the project. Blowing up a charge of plutonium is easy, making a proper nuclear blast is one of the highest-level techs there is aside from rocket science.

            And that's a good thing too, otherwise there would be much too many madmen with a twitchy finger on a launch button.

            1. The First Dave

              Nuclear Bombs are neither Rocket Science, nor Brain Surgery.

              That is why those two maintain a duopoly in that particular cliche market. Building a working nuclear bomb is very very hard, no doubt about it, but if a small bunch of septics could build one in the 1950's, with no computers to speak of, and with no 'prior art' then it is little more than a matter of effort these days. (And access to fissile material)

              1. TheRealRoland


                yeah, those radiation wounds start festering after a while...

            2. Trevor_Pott Gold badge

              @pascal monet

              Building an implosion type nuke is about as hard as a space plane. Building a gun type nuke is child's play.

              An implosion type nuke is what you need to put on a ballistic missile. It also can theoretically scale up to at least a hundred megatons. A gun-type nuke is something you'd be lucky to get a handful of kilotons out of.

              They are completely different devices.

          2. Anonymous Coward
            Anonymous Coward

            Re: Once something become possible

            >Basic nukes aren't hard. They require zero engineering experience (for a gun-type nuke.)

            If I remember correctly, New Scientist published a spoof article (around 1982 +/- 2 years) which suggested you could build one in a terraced house if you didn't mind what the neighbours would say about you using an old pram to ferry raw ingredients around while all your hair was falling out and the walls started dimly glowing in the dark....

            (If anyone can point me to this article, I'd love to see it again. Yes, I have looked for it before now ...)

        2. Trevor_Pott Gold badge

          Re: Once something become possible

          1) I live in Alberta. Strikes me that a good chunk of the world's supply can be dug out of the ground not far from here. It doesn't take much to find a mining company with some rights to prospect up there and piles of equipment either. IIRC NK has deposits of it's own, and they can buy from the Chinese.

          2) You don't need a neutron initiator for a gun-type nuke. They make it more efficient, but if you wanted efficient (as opposed to a self-spreading dirty bomb that makes a small crater) you wouldn't be using a gun-type nuke in the first place.

          3) IIRC, it's about 20 lbs of Uranium at 80% for the design I know best. Yes, there are all sorts of risks to the design for things like squib explosion and shattering the bullet, but to remember that you don't have to ram the pieces together very large. You need to get subcritical mass A into subcritical mass B such that they go supercritical all on their lonesome and they make a boom.

          If you really wanted to point to the difficulty of making a nuke you'd talk about refining the Uranium. Going from raw ore to even 20% enriched U238 (let alone the 80% needed for most primitive gun-type designs) borders on dark magic. You're basically talking about needing a gas centrifuge. How - exactly - one goes about that without killing everyone from Uranium hexafluoride poisoning - let along the possibility of inhaling some of the radioactive fun stuff - I have only the barest inklings of a clue.

          Gas centrifuges are fair simple. Gas centrifuges that have to deal with something that corrosive and can't be allowed to leak even the smallest amount at any stage due to the radioactive nature of the product? Crazy stuff, right there.

    2. 4ecks

      Re: Once something become possible - nearly all you need to know about basic weapon design and construction, it's fairly easy to make a nuke. Weaponising it takes a bit more effort, harder still to get it to fit the pointy end of a missile. However it is not like you want it to come back and land for reuse once you've lit the blue touch paper.

      Making a reusable & reliable rocket/space plane takes mathematics, engineering, physics, chemistry, materials science, electronics, computing etc. AND more political desire than for using these to make bombs.

      A lesson from history -

      “ All modern aircraft have four dimensions: span, length, height and politics. TSR-2 simply got the first three right. ”

      — Sir Sydney Camm

  7. Vociferous

    DARPA is basic science,

    Not applied science. Their job isn't to develop commercial products, it's to develop new technologies which are too expensive or where the payoff is too distant or too uncertain for commercial companies.

    Which, effectively, is all technologies which can not be monetized in less than five years.

    So I like DARPA.

    One should however remember that their prime goal is military. The hypersonic aircraft they're researching aren't intended to shuttle businessmen from New York to London or cargo to the ISS, they're intended for rapid deployment of bombs and troops anywhere in the world.

  8. MrXavia

    Don't count out Skylon yet!

    the pre-cooler works it is the primary new technology they needed..

    They are funded right now, I am positive as soon as they get a working Sabre engine finished, they will get more backing...

    And since they plan to sell them rather than run them, they don't need the capital to go all out and build a fleet, just get to the point buyers are confident!

    I really hope the UK gov decides to fund it soon

    1. TheOtherHobbes

      Nah. HMG are going to spunk £50bn on a train set, while turning down funding for Skylon because it's 'not cost effective.'

      Skylon should talk to Musk. They might not get along, but it would be fun to sit in on the meetings.

    2. John Smith 19 Gold badge

      "I really hope the UK gov decides to fund it soon"

      Already in the works, as described here

      And of course by El Reg.

  9. i like crisps

    'Unidentified Fibbing Object'

    Instead of messing around with rockets couldn't those nice people

    from DARPA just pop over to AREA 51 and borrow a couple of flying saucers

    for the weekend? I'm sure DARPA's tech's would be able to reverse-engineer

    the craft for their own benign purposes thus saving themselves and the

    American taxpayers ('us') a lot of time and expense...hows that for some

    'Blue Sky Thinking'?

  10. jonathan keith


    An article about scramjets and no mention of lighting matches in hurricanes? I tell you, the quality of reporting here is going downhill rapidly. I may have to cancel my subscription.

  11. Anonymous Coward
    Anonymous Coward

    But surely gravity is the problem here. So reduce that to a much less or even negative and getting stuff into space is simple.

    (I'll leave creating an anti-gravity device as an exercise for the reader - is anyone researching if there is a way of creating artificial- / anti- gravity?).

    1. loneranger


  12. Rustident Spaceniak

    Why bother with a scramjet? And why worry about the thermal insulation?

    You only need a scramjet for this if you want maximum efficiency for maximum dollars. If "feasible and affordable" is the word, launch with a normal turbofan, go to Mach 3.5 or so with that at a reasonable altitude, and do the rest with a rocket. You can always play around with combined cycle a bit, inject some oxygen into the turbofan intake to get you as far as Mach 4 and maybe 50km up or so, but at the end of the day a rocket will do the job best - specially one fed from the same kerosene tank you've been using for that turbofan.

    Regarding the thermal insulation, you're talking about a Mach 10 re-entry, not Mach 28. That's a totally different league. Mach 10 can be done with quite solid, light ceramics as demonstrated by the German Shefex-II experiment last year.

  13. disgruntled yank Silver badge

    and why not

    the project name "Wretched XS-1"?

  14. SirDigalot
    Paris Hilton

    always confused about brain surgery

    for the longest time they chopped the skull cap off and randomly probed in areas they figured would be the bits that controlled stuff then made note of it.

    not saying they are not smart (chopping the skull off with a conscious patient I can imagine it a tad tricky, especially with the old blobby sac of neurons right below it), but it seemed more like a living game of operation than being a rocket scientist.

    then we have trepanning technically early brain surgery also, they have been doing that since we found we could drill a hole in our head with a piece of flint.

    we have not gotten to the whole Glue neurons back together level yet, in that respect I figure rocket scientist > brain surgeon

    that said I guess it is the whole "one-shot" deal, you can often find a bunch of brave citizens to sit atop a firework, not so easy when there is only one brain and no transplant option ( though that would be really cool brain surgery).

    >>>>>>>>>>>why paris? as unrelated as my musings...

  15. Kharkov

    Meh, not impressed...

    DARPA is a day late and a dollar short. Granted, they've got billions of dollars to make up for that but...

    They're aiming at a low-cost, reusable smallish engine which will take around... 5 years? 10? of development & testing just so they can cheaply and frequently put... 1,800kg (probably a bit less what with weight growth etc).

    Hmm, what's highly likely to be in service in 5 to 10 years time? Well, chances are there'll be a reusable Falcon 9, putting 6,000kg into LEO for... 40 million dollars a shot? Will DARPA's effort beat that on price per kg?

    And over in the UK, chances are there'll be Skylon, putting 15,000kg into LEO for 10 million dollars? Granted, this is a bit more unlikely than just developing a currently-operating Falcon 9 rocket but while people point out the amount of money REL needs, no-one's clearly demonstrated why REL won't eventually get it.

    So, lots of money spent, technology developed by DARPA and afterwards classified out the whazoo. FAIL

  16. Gene Cash Silver badge

    At least the USAF is doing something with the X-37B

    NASA tossed it directly in the waste bin without a second thought, and the USAF rescued it. Considering the success they've made of it, I hope they're testing all the niftycoolspystuff their hearts desire.

    1. MD Rackham

      Re: At least the USAF is doing something with the X-37B

      When Congress cuts your budget, you have to cut somewhere. So some projects get tossed in the waste bin.

      You can argue NASA's priorities, but research projects with no immediate application tend to always get cut before the big splashy projects (Mars Opportunity, JWST, etc.).

  17. John Smith 19 Gold badge

    Just a few misconceptions.

    It's not going to cruise at M10, it's got to reach M10

    Could be an hour+, could be a minute+, could be 5secs. It's all good (although they may think 1 hr at M10 is better I think that claim is likely to trigger the BS detector big time).

    With that spec there's lots of room for "creative engineering interpretation."

    "Cheating" is for exams IRL if it gets the job done, it gets the job done. End of.

    That said anyone talking SCRamjets is also talking stupid money.

    OTOH the USAFRL got a plane in the air with an actual meatsack at the controls on a Pulse Detonation Engine in 2006. Only something like M0.8-1.2 but it was v 0.8 tech at best and they are sure they could do much better.

    Incidentally that M10 is not even clear if it's M10 horizontal (leaving the other M13 to the 2nd stage) or vertical (a whole different ball game).

    BTW This project is being headed by Jeff Sponable, who ran the SDIO DC-X programme that built a VTOL M3 demonstrator for about $60m in the early 90's. The RFI talks about an "aircraft" but later in it says "aircraft like," which is also a whole different game.

    Trouble is until the "contractor open day" there's a lot that's up in the air (pun intended). 1000-4000lb fair enough but what's the shape? Form factor? Payload density? That will make a huge difference to what could work for this.

    I'd (more or less) agree with Trevor-Potts comment about this. Conceptually a simple nuke is fairly simple to construct. The AEC hired 3 Physics PhD candidates in the late 60's to try to design one given what was available in the open literature and could be purchased from the USG Printing Office. Their report is (AFAIK) still classified.

    I'll suggest that what needed 3 PhD;s 4 decades ago has come considerably down the food chain, although I'm not quite ready to say "Nuclear terrorism for skiddies" yet.

    No I can't do it. I do not hold a security classification with any organization. I'd suggest a key feature is how enriched the U235 has to be to get a fair chance of a bang. Historically that's meant to have been about 70%+ HEU, but AFAIK some have been done in the LEU range (4-20%). As water cooled reactors don't work without enriched Uranium (except the original CANDU design, which sidesteps the whole enrichment problem) that means probably 80-90%+ of the worlds reactors could source the core raw material for some unpleasantness, which implies 80-90% of the countries that have reactors could source a device of varying levels of sophistication.

    OTOH damm few countries have built aircraft to exceed M3. IIRC the US, USSR and (I think) France and that's it. The UK would probably be in there if was not for that rampant todger bandit Duncan Sandys, but we've all passed a lot of water since those days. :(

    OTOH 2 consider how many countries have achieved orbital launch where the LV routinely stages at M10.

    VTO is relatively easy.

  18. amanfromMars 1 Silver badge

    Misunderestimate Fabless Future IntelAIgent Fantasy and Super Attendant Fanaticism at One's Peril

    DARPA have bigger phish to fry and greater phorms of programs to launch and feed with world leading projects ........ ...... or be left behind reacting to everything flashing past them and crashing into crazy maladministered earthed systems of ill repute that do not compute or play well with the future and easily destroy everything and/or anything with timeless asset bubbles of expensive useless worth ..... for such things are easily made to happen nowadays with that which be now more widely known is possible .... and selflessly carefully shared with more than just an ancient few and/or ancients and a chosen few who imagine themselves as the Chosen Few. Hubris rules in that roost, methinks.

    After all, one wouldn't want to be unduly startling the natives and creating a great panic and global depression and world wide recession with a mad and manic settling of age old scores with a French Revolutionary zeal, would one, with a careless sharing of exciting information and newly discovered advanced intelligence.

  19. Anonymous Coward
    Anonymous Coward

    Nurse! Nurse!

    I see AmanfromMars1 seems to be off his meds again . . .

    Demerol, 1,000 cc IV, please. If that doesn't work, double the dosage. If that doesn't work, double it again.

    I'll be on the golf course for the rest of the day, leave me a voicemail in the morning.Ta.

    1. amanfromMars 1 Silver badge

      Re: Nurse! Nurse!

      Nurse! Nurse!

      I see AmanfromMars1 seems to be off his meds again . . .

      Demerol, 1,000 cc IV, please. If that doesn't work, double the dosage. If that doesn't work, double it again. …. Anonymous Coward Posted Wednesday 18th September 2013 19:12 GMT

      It is just exactly that sort of ribald comic response to an Informative Steganographic Advisory that allows ACTive Stealth with AI and IT every Facility and Utility to Succeed beyond the Wildest of Wicked Wacky Wet Dreams and Creative Imaginanations of a Renegade President, AC. Thanks for everything. IT is just so kind.

      I'll be on the golf course for the rest of the day, leave me a voicemail in the morning.Ta.

      Consider it hereby done with the message above via text to your lonesome oval office space.

      Wanna Play the Great Game for Real with Virtually Real Command and Control? Who Dares with IT Win Wins Everything in Anything and in All Ways, Always. It certainly beats knocking a small ball around an expensive course with grassy knolls and sandy bunkers and expecting it to be satisfying rather than boring snoring.

      cc @iankatz1000 ....... re Alternate Reality Games in AI Register for Mainstreaming News Knights.

      Capiche, Cheltenham/Martlesham Heath?

  20. loneranger

    old technology again

    Electrogravitics beats this stuff by light years

  21. YARR

    Keeping it simple

    1. Grasshopper - rather than expand fuel controlling it's descent, wouldn't a couple of tiny wings allow for a (computer) controlled descent as a cumbersome glider? Falling from that height it would reach such a high velocity that tiny wings ought to be enough to gradually steer it to a horizontal landing, kind of like an X-15. Or is that idea just impossible?

    2. XS-1 - this is probably stating the obvious, but if the second-stage rocket is non re-usable then it would make sense to design it so the rocket acts as the heat shield for the XS-1 on the ascent. Then immediately after separation the XS-1 can switch off it's engine and begin aero-braking. This ought to minimise the length of time it's leading edge has to withstand the intense heat.

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