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The Military Transportation Technology

Mach 6 Test Aircraft Set For Trials 131

Posted by Soulskill
from the fly-her-apart-then dept.
coondoggie writes "The aspiration that jets may someday fly at over six times the speed of sound took a very real step toward reality recently, as the US Air Force said it successfully married the test aircraft, known as the X-51A WaveRider, to a B-52 in preparation for a Dec. 2 flight test. The X-51A flight tests are intended to demonstrate that the engines can achieve their desired speed without disintegrating. While the X-51 looks like a large rocket now, its applications could change the way aircraft or spaceships are designed, fly into space, support reconnaissance missions and handle long-distance flight operations. At the heart of the test is the aircraft's air-breathing hypersonic scramjet system."
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Mach 6 Test Aircraft Set For Trials

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  • Hmmm... (Score:5, Insightful)

    by voss (52565) on Saturday September 05, 2009 @12:38PM (#29323931)

    Engines reaching desired speed without disintegrating....thats a GOOD feature to have.

    • Only if you want the chimp to survive. Some stories unfold when man and ape work in close quarters that just shouldn't be allowed to be told.

      • Rockets vs Scramjets (Score:5, Interesting)

        by sanman2 (928866) on Saturday September 05, 2009 @01:00PM (#29324099)
        Rocket supporters say that it's better to clear the atmosphere asap, and accelerate cleanly in a frictionless environment. Scramjet supporters say it's better to accelerate inside the atmosphere as much as possible to exploit its available oxygen, rather than carrying it as extra weight.

        Which costs more energy - carrying the extra O2, or overcoming the friction from having to accelerate in an atmosphere? Which imposes more design compromises?

        Which would be more economical in the long run? Bear in mind that there are 2 kinds of people that need to achieve very high velocities -- astronauts trying to make orbit and intercontinental travelers trying to get to the other side of the world.

        • Re: (Score:3, Insightful)

          Which would be more economical in the long run?

          Depends almost entirely on how fast you can get on scramjets. I don't think Mach six is enough to make it worth the bother. But I'm pretty sure Mach twelve would be enough to make it worthwhile.

          • by TheLink (130905)
            For short trips e.g. New York to London it's not worth it whether it's Mach 6 or Mach 12 - the gains you have would be overshadowed by the hours you spend getting to/fro the airport and getting through the airport to/fro the plane. For longer trips yes - e.g. New York to Singapore, or London to Auckland. On the bright side maybe if your luggage ends up on the wrong flight (to Hawaii?) it won't take as long for them to get it back to you.

            Seriously though, when you talk about economical - you have to ask how
            • How do you define "economy"?

              Isn't it all relative?

              Compare a bus ticket, to a plane ticket, to a cruise ticket...
          • Re: (Score:3, Interesting)

            by HiThere (15173)

            It's worth remembering that Mach numbers are dependent on the current speed of sound.

            If a scramjet can reach over 7 miles/second in the very upper stratosphere, then the scramjet would clearly win....at least if it didn't need the same G forces as the rocket. And particularly if it could carry a sizable cargo. (I.e., anything better than an Apollo capsule, but the larger the better.)

            A scramjet might make an admirable second stage for a rocket, but then you need a first stage to get it up to speed. Note t

            • Re: (Score:3, Insightful)

              by cheesybagel (670288)
              The problem with using scramjets is that you need another engine for liftoff, and yet another engine for space travel (scramjets are made for travelling inside the atmosphere at only startup at a certain Mach number). With a rocket engine you only need *one* engine to go for zero velocity to space. In other summary, scramjets make no sense for space travel.

              Scramjets would be nice for a high speed reconaissance platform or bomber though.

              • by daver00 (1336845)

                You fail. Current rocket designs use multiple stages to get into orbit, that means multiple engines, plus whatever the payload is it will have its own engine as well. The thing is that rockets are incredibly simple engines, they simply throw their mass away to achieve thrust, thus the amount of mass you can move is a function of the fuel you can carry and vice versa. With scramjets you can take mass from the atmosphere, raise its energy and then throw it away, thus a portion of your fuel is collected along

                • No, it is you who don't understand. A scramjet has a low thrust-to-weight ratio, which means to get up to speed takes a lot longer than a rocket. It also only works in the atmosphere. At those speeds you will need cooling for the entire skin of the vehicle. Which means you will lose a lot of payload just for that cooling system which wouldn't be necessary if you had a rocket where you want to get out of the atmosphere as soon as possible.

                  Scramjets are useless for space vehicles.

                  • by daver00 (1336845)

                    I wasn't claiming that scramjets are without problems, I merely pointed out that current rockets already have multiple engines, which you kind of claimed they do not.

              • by Jarnin (925269)
                In the television series StarGate SG-1 and StarGate Atlantis they have a top secret alien-human tech derived aerospace fighter called the F-302. It uses 3 forms of propulsion in order to do what it needs to do:

                2x regular air-breathing jet engines for low altitude operations.
                2x scramjets for high altitude operations.
                1x Rocket booster to get into orbit.
                • In the television series StarGate SG-1 and StarGate Atlantis

                  Erm... In the television series Star Trek they have matter/anti-matter reactors and warp drives capable of traveling faster than the speed of light.
        • by DynaSoar (714234)

          You start to answer your own question with the "two kinds of people" statement. Rocket supporters and scramjet supporters, whatever those are, might take up the cause of a particular vehicle. But the point is not to use a particular vehicle, it's to get something done using the most effective and efficient vehicle available.

          You start with your goal, develop flight profiles for the available vehicles, add in ground support and maintenance costs, and calculate your costs/benefits.

          There are more than "2 kinds

        • Which costs more energy - carrying the extra O2, or overcoming the friction from having to accelerate in an atmosphere? Which imposes more design compromises?

          Seems the best answer is likely somewhere between the two. I mean the idea behind scramjets is only to get you through part of the journey anyway. You'll still need a running start, and you'll still need to carry oxygen to get you up into space.

          Which would be more economical in the long run? Bear in mind that there are 2 kinds of people that need to achieve very high velocities -- astronauts trying to make orbit and intercontinental travelers trying to get to the other side of the world.

          What about people trying to get a few kilometers downrange and get blown to smithereens the other end? Missiles are people too, y'know.

        • by cenc (1310167)

          "Which would be more economical in the long run? Bear in mind that there are 2 kinds of people that need to achieve very high velocities -- astronauts trying to make orbit and intercontinental travelers trying to get to the other side of the world."

          I would add, bombers getting to their target and home for dinner.

    • Re: (Score:3, Funny)

      by KangKong (937247)

      Nice to be the test pilot. "Increase the speed to mach 6, we're just gonna check that the engines don't disintegrate."

    • Re: (Score:3, Interesting)

      by Z00L00K (682162)

      The biggest problem for general use is to achieve speeds above about Mach 3.5.

      This was roughly the maximum speed for the SR-71 and the problem was the friction heat from the air. And the SR-71 had a hull of Titanium. The Concorde did achieve about Mach 2 and had a hull from Aluminum. So for commercial use it's probably not practical to exceed the speed of the Concorde. What has to be done for commercial use is to get a more economic version and a version that has a less annoying sound bang.

      But there is a us

      • by PeterM from Berkeley (15510) <petermardahl@@@yahoo...com> on Saturday September 05, 2009 @01:09PM (#29324159) Journal

        Recent advances [technologyreview.com] in the production of titanium may bring this metal into wide use in airframes. And everything else.

        • by dpilot (134227)

          How much titanium is there, laying around, if the demand would suddenly start to rise?

          How much of that titanium is locked up by China, who has seen for some time that strategic metals will become a growth limiter in the not-so-distant future?

          • by modecx (130548)

            How much titanium is there, laying around, if the demand would suddenly start to rise?

            How much of that titanium is locked up by China, who has seen for some time that strategic metals will become a growth limiter in the not-so-distant future?

            A lot. It's pretty abundant, actually. It's just that with current processes, it's goddamn expensive to produce, uses large amounts of chlorine and energy, etc... That's the only practical reason for its rarity as a structural material.

            AFAIK, China doesn't produce a sig

            • by dpilot (134227)

              I thought about white pigment a few minutes after posting.

              As for China, I said "locking up", because they're investing heavily in Africa, for instance. The stuff they want may not be on their territory, but they're very present in places where those things are.

              Now that I actually take a look, Titanium is 22 and Iron is 26, and the contentious Lanthanoids are 57-71. (No doubt higher stuff will be scarcer.)

              • by modecx (130548)

                They're present alright, but even discounting the whole continent of Africa, there's almost cerianly enough to keep the rest of the free world humping along, elsewhere. Oil or copper will be much more immediately contentious of a resource, all other things considered.

                When or if it becomes more economically viable (profitable), Ti mines will certainly start up.

              • by WindBourne (631190) on Saturday September 05, 2009 @07:50PM (#29327463) Journal
                Actually, China is trying hard to lock up LOADS of resources all over the world, but the biggies are Rare Earth minerals as well as Uranium. This last week, they quit exports of a select group of REMs that they have control of, and others that they do not have total control of, they dropped the possible exports. At this very moment, Australia is deciding whether to sell them several of their mines. Hopefully they do not as they are REM mines and will be needed by the entire rest of the world. These minerals are concerned with making permanent magnet motors that are going into Electric Cars as well as are used in nearly all electronics.
          • Re: (Score:3, Informative)

            Ti is the 9th most abundant element in the crust (7th most abundant metal).

            The wiki page answers all your questions.

            http://en.wikipedia.org/wiki/Titanium [wikipedia.org]

            Ti is abundant enough that we use it in toothpaste and toilet cleaner; I don't think you need to worry about it going anywhere.

            -b

          • There is a lot of titanium. Titanium oxide is used as the pigment for white paint. If you ever tried buying paint, you probably realized white paint is usually cheapest. So there.

            The issue is how do you turn titanium oxide into pure titanium. This process seems somewhat similar to the Fray-Farthing-Chen process. Then again I remember that used to be a hot topic at the time, but it never got to production.

    • by oldhack (1037484)

      Engines reaching desired speed without disintegrating....thats a GOOD feature to have.

      Kids these days. Back in my days ... never mind.

  • by imashination (840740) on Saturday September 05, 2009 @12:51PM (#29324027) Homepage
    Mach 6, how blades is that?
  • by MRe_nl (306212) on Saturday September 05, 2009 @12:59PM (#29324093)

    WHOOOSH!

    (ducks)

  • This appears to be more about the development of a hypersonic cruise missile [popularmechanics.com] than an actual aircraft.
  • by Stan Vassilev (939229) on Saturday September 05, 2009 @01:07PM (#29324149)

    While the X-51 looks like a large rocket now, its applications could change the way aircraft or spaceships are designed, fly into space, support reconnaissance missions and handle long-distance flight operations.

    The Concorde flew at 2.2 Mach and in order to achieve this, it ended up too expensive to create, manufacture and maintain. It would be awkward to see airlines adopt airplanes which are more expensive to fly than current models. The trend is towards less fuel usage, and cheaper flight, in fact, at the expense of speed at times. On the other hand I'm happy to see that US is working heavily on creating a replacement for F-22, an insanely expensive jet with a nearly 30 year history that was barely ever used for something at all, before being discontinued :P...

    • Re:Not for aircraft. (Score:4, Interesting)

      by maeka (518272) on Saturday September 05, 2009 @01:20PM (#29324235) Journal

      When calling the Concorde (or any other aircraft) "too expensive to create, manufacture, and maintain." on needs to take into account the ticket price the market will bear.
      Since the Concorde was not designed with a range suitable for flying the Pacific routes, it was forced to try to make up it's high costs on the much tighter margins of the Atlantic routes. Had it been able to fly the higher margin Pacific routes it is quite possible it would not have been too expensive to be sustainable - even at the same (or slightly higher) cost basis.

      • Re:Not for aircraft. (Score:5, Interesting)

        by moosesocks (264553) on Saturday September 05, 2009 @01:41PM (#29324387) Homepage

        The concorde was profitable in its last years (not extremely profitable, but it made money, which is more than most airlines can currently say).

        In the end, its operators decided it wasn't worth maintaining/refurbishing the planes, scrapped the program, and wouldn't let competitors purchase the unused aircraft. Richard Branson allegedly made several serious offers for the planes, all of which were rejected. Numerous allegations have been made that the grounding of the Concorde fleet was a result of a conspiracy between Airbus and the airlines (unsubstantiated, but certainly plausible, especially in light of their refusal to sell the craft to other carriers at a time when the company was losing money)

        In short, we got lazy and stupid.

      • Re: (Score:3, Insightful)

        by DerekLyons (302214)

        When calling the Concorde (or any other aircraft) "too expensive to create, manufacture, and maintain." on needs to take into account the ticket price the market will bear.

        And on that issue - the market has spoken loudly and clearly. "It ain't worth it".

        Yeah, I know the Concorde made a paper 'profit' towards the end - but the proof is in the amount of money the airlines were willing to spend to keep this 'profitable' airliner in operation, which coincidentally is equal to the number of Concorde's s

        • by maeka (518272)

          And on that issue - the market has spoken loudly and clearly. "It ain't worth it".

          I assume it was unintentional that you missed the rest of my post, but let's be clear - the Atlantic market has spoken, not the market as a whole.
          The Concorde could not fly the profitable Pacific routes due to limited range, and it could not fly supersonic over mainland USA or Europe due to noise regulations. This greatly limited the market segment it participated in.
          This need not be the case (well, the noise issue likely doe

          • Re: (Score:3, Informative)

            by wagnerrp (1305589)

            This need not be the case (well, the noise issue likely does) with a future supersonic passenger aircraft.

            There is no regulation against flying supersonic over the continent. The regulations are for maximum decibel levels generated over populated areas. You can fly high enough that the pressure waves have dissipated by the time they hit the ground, although this has been found to have limited effect. You can design your fuselage and wing such that the pressure wave is spread out over a longer area, and directed laterally, so it never spikes above the limits. There is been a lot of work in that area over the

            • by maeka (518272)

              There is no regulation against flying supersonic over the continent.

              I never suggested there was.

              The regulations are for maximum decibel levels generated over populated areas.

              Which is what I said.

              You can fly high enough that the pressure waves have dissipated by the time they hit the ground

              That has proven to be awfully high.

              although this has been found to have limited effect

              Though you appear to know that.

              You can design your fuselage and wing such that the pressure wave is spread out over a longer area, and

        • I think you need to refine your stance. "The Market" has not spoken loudly and clearly; "A Market" at a specific place and time has spoken. Supersonic trans-atlantic flight has been shown, in hindsight, not to work in a very specific place and time in history. That's all. It has not proven that it can never be done.

          Analyzing failures are helpful for gaining insight into processes, but the failure of one instance shouldn't be taken as a broad indication that the idea itself is a failure. It may simply be the

        • Re: (Score:3, Informative)

          by smoker2 (750216)
          Utter shite [wikipedia.org]. No amount of money would have kept the manufacturers in the business of maintaining the airframes. They have too much else to do. The airlines didn't shut it down, the manufacturers did. Without a place to go for regular maintenance, you don't keep your airworthiness certificate. This means you don't fly. And the airlines did indeed spend a lot of money to try and mitigate the mechanical circumstances of the Paris crash, which wasn't even their fault. Crap on the runway is crap on the runway, n
          • Utter shite. No amount of money would have kept the manufacturers in the business of maintaining the airframes. They have too much else to do.

            Horseshit. If there was money to be made in it, they'd have still been in it.

            With recent advances in engine design and composite technology, a new supersonic plane would not consume so much fuel and would doubtless get longer range, given it's only a matter of initial design choice.

            Weight isn't the problem for supersonic aircraft - you could cut the w

    • by Myrcutio (1006333) on Saturday September 05, 2009 @03:18PM (#29325197)
      The F-22 wasn't created for our time, it's intended use is to aid our future brethren in overthrowing their tyrannical alien overlords. See the documentary here [wikipedia.org].
    • It's no Concorde in any sense. The Concorde was created to make an efficient aircraft, not a fast one. This is the history I learned in college:

      Jet engines are more economical the faster you get. Too bad the air friction (drag) gets worse the faster you get. For subsonic aircraft with single flow engines, the optimum lies just a bit below the speed of sound. As there were only single-flow jet engines at that time, the Concorde was created to try to shift the optimum to above the speed of sound. They succeed

    • The f-22 didn't take much longer than other 5th generation aircraft. Oh wait, the F-22 is the ONLY 5th gen fighter in the world. And it only just went into service. And frankly, I don't want us to ever *need* it- Needing an f-22 would require an enemy with excellent air power, which would mean that we were fighting a major power such as china, india, or russia.

      Do you complain that our nukes don't get used often enough?

      -b

    • by Patch86 (1465427)

      Lets please try to remember that the Concorde was originally designed and built 40 years ago, That's -4-0- years. Despite the fact they obviously would have refined and upgraded wherever possiblle in those 40 years, it's still a 40 year old vehicle.

      Please find for me, if you can, any other aircraft which first flew on or before 1969 which is still being used, profitably, for trans-continental passenger services today.

      Technology marches on. Concorde being withdrawn from service after 27 years in action prove

  • http://www.hq.nasa.gov/office/pao/History/hyperrev-x15/ch-0.html [nasa.gov]

    perhaps one of the tags should have been "been there, done that"
    • by jklmuk (1383691)
      http://www.nasa.gov/missions/research/x43-main.html [nasa.gov]

      nasa have already achieved mach 9.6. Mach 6 should be a walk in the park

      • by wagnerrp (1305589)
        They ran the engine for 10 seconds. With that limited duration, a bit of ablative material on the skin, and you're fine. Running for 5 minutes and 350 miles is considerably more difficult.
        • by jklmuk (1383691)
          where are you getting the 5 minutes from? the article talks about 60s which is such a great achievement when you are going 50% slower. Meaning the temperatures that the plane/missile experience will be significantly lower.
      • by PachmanP (881352)
        The key is sustaining power. The x43 engines where basically big copper heatsinks. The goal was to demonstrate demonstrate supersonic combustion before the engine melted. I believe the goal for this one is to be able to run an engine that doesn't melt.
    • by jnik (1733)
      The X-15 used rocket engines (carried its own oxidizer). This is a jet, using oxygen from the air.
  • Real step? (Score:4, Insightful)

    by SlayerofGods (682938) on Saturday September 05, 2009 @01:12PM (#29324191)
    The X-43 [wikipedia.org] already did mach 9.68.
    This is actually a bigger step towards making a mach 6 missile [popularmechanics.com] rather then a mach 6 plane....
  • For some reason at first glance I read "Mach 6 Test Aircraft for sale" and I reached for my wallet...

    • You can buy one for $39.99 right now [hasbrotoyshop.com]. Of course you'll have to learn scottish to make some of the things work.
      • by skyride (1436439)
        Damn you all Slashdot! I am scottish, however the link has been slashdot'd so I am unable to fulfill my dreams! Damn you all!
      • by clem (5683)

        Of course you'll have to learn scottish to make some of the things work.

        I have Tourette Syndrome. Does that count?

  • Cool but... (Score:3, Interesting)

    by Brad1138 (590148) <brad1138@yahoo.com> on Saturday September 05, 2009 @02:05PM (#29324531)
    What ever happened to the Aurora [wikipedia.org]?
  • by PPH (736903) on Saturday September 05, 2009 @02:25PM (#29324693)
    ... they could save me more travel time by not making me take my shoes off and stand in endless, pointless security lines.
    • by D Ninja (825055)

      I so wish I had mod points.

      What's great is that, even given today's security measures, 9/11 would have still happened. Nothing that those terrorists did on 9/11 would have broken today's laws.

      • by D Ninja (825055) on Saturday September 05, 2009 @05:21PM (#29326441)

        Hmmm...I'm reading my post, and I don't mean to say that it would be great 9/11 would still happen. Don't get me wrong - 9/11 sucked and I would never want that to happen again. But, when I say "what's great" is the fact that nobody seemed to stop and think about how pointless many/most of the security measures actually are. (AKA, I was attempting sarcasm and it definitely did not come through...my apologies.)

        • by TimSSG (1068536)
          Other than the reinforcing of the cockpit doors, was there a security change that might stop an hi-jacking? Tim S.
          • by PPH (736903)

            They didn't kick in the cockpit door. They killed a few passengers/cabin crew and the pilots let them in. SOP at the time was: cooperate. Let them hijack the plane. The worst that will happen is a trip to Havana.

            Not any more. Cockpit door, box cutters or not, odds are that the passengers will kill the hijackers. All the pilots have to do is land the plane fast.

          • My friends children were invited into the cockpit by the pilots in jan 2002. Reinforcing cockpit doors did nothing.
    • I was looking at flying to a meeting in Germany from Austria. However even a 5 hour train ride works out quicker than the 1 hour flight with all the extras (including traveling to and from the airports).
  • Since most vehicles, including aircraft, are named after girls, would this be considered a gay marriage?
  • by speedlaw (878924) on Saturday September 05, 2009 @02:52PM (#29324977) Homepage
    At some point, some of the Black projects bear fruit. We now need to admit that this can happen, now that we want to go big with it. Sorta like stealth, we had it for a while but at some point needed to go "white" with it. If it is ready for prime time, cool. You didn't think the SR 71 wasn't replaced, did you ?
    • Re: (Score:3, Informative)

      You didn't think the SR 71 wasn't replaced, did you ?

      Um... Yeah, it was replaced... With *satellites*.

      And just a word of wisdom from someone who works for 'the dark side': Supersonic aircraft are not stealthy--http://en.wikipedia.org/wiki/Sonic_boom [wikipedia.org]

      http://www.pbs.org/wgbh/nova/xplanes/stea-flash.html [pbs.org]

      -b

    • The SR-71 was replaced. By spy satellites. Ever used Google Maps? That uses satellites photos. Now imagine something higher resolution and with dynamic updates.
      • by speedlaw (878924)
        Yes, but the problem with sats is that everyone knows when they go by. A fast plane is not predictable. Mach five with stealth, even minimal stealth, will be in and out before the enemy can do anything.
        • by toolie (22684)

          Yes, but the problem with sats is that everyone knows when they go by. A fast plane is not predictable. Mach five with stealth, even minimal stealth, will be in and out before the enemy can do anything.

          And miss most things of any tactical value in that time. There is a place for fast places, in strategic recon, which happens to be a lot harder to hide from satellites. We are going toward slower (I prefer the term lumbering) platforms with awesome endurance for tactical recon, staring is better than glimpsing in that case.

  • Is that somewhere around Warp 2?
  • Scramjet tech is worthless. It's not a very good weapon - a scramjet is going to have one heck of a heat signature and probably can't be very stealthy. Not just from the exhaust...at Mach 6 the entire aircraft/missile is going to be glowing red from heat. Also, air to air missiles (like the Patriot) that use rockets already go that fast.

    Second, it's worthless for getting stuff into orbit. The reason is simple - the reason a rocket costs so darn much has nothing to do with fuel. It has to do with comple

    • Re: (Score:3, Insightful)

      by WindBourne (631190)
      Scramjet is one of the easiest engines to build. In fact, they will be a great deal less expensive for maintenance. It is just difficult to get it correct. It will also be difficult to get it up to the speed. Right now, we are using a rocket to get there. But down the road, we will likely use a ramjet which will be inefficient taking off (probably will use an electronic runway launcher to get going), all the way to the mach 5.
    • Re: (Score:3, Insightful)

      by pohl (872)

      You sound very sure. I'm curious, how would a Patriot (traveling at its top speed of Mach 5) overtake and intercept something traveling at the same (or greater) speed given that the latter has a rage of 600 nautical miles and the former has a range of 99 miles?

      Are you sure that stealth is a priority given the X-51's intended mission [popularmechanics.com]?

      • Fine. Use a Russian S-300 PMU then. Or if you are from the USA an Aegis using RIM-161 Standard Missile 3. If you can only get Israeli, an Arrow missile [wikipedia.org]. If you need more range you just require a larger missile.
        • by pohl (872)

          None of those have the range necessary to overtake something at that speed. These are all anti-ballistic missiles, and the X-51 isn't a ballistic missile. At best, one would need one of these near the target site in order to get lucky. Given the purpose of the X-51, this seems unlikely.

    • by rcw-home (122017)

      The reason is simple - the reason a rocket costs so darn much has nothing to do with fuel. It has to do with complexity - it's very expensive to make something as complicated as a rocket work under all the stresses of a launch.

      All of that complexity in turn stems from the insanely high mass ratios that chemical rockets require to achieve orbital velocity (93.5% of the Shuttle's weight is fuel/tank/boosters). That, in turn, means the rocket itself must be made as lightly as possible; you cannot merely overen

      • Also, most of the complexity of a scramjet is in the design of the shape. This test vehicle has only one moving part, the fuel pump.

        A rocket engine's most complex part is also the fuel pump... Unless you use pressure-fed engines, in which case you don't even need a pump at all!

        You cannot reach space using just a scramjet anyway. You need rockets. There is no air in space.

        • by rcw-home (122017)

          You cannot reach space using just a scramjet anyway. You need rockets. There is no air in space.

          Obviously. But a rocket that only has to add that last third or fourth of orbital delta-v can be designed a lot more conservatively and carry a lot more payload (which means a lower cost per kg to orbit). This scramjet is maneuverable - it can stay in air to breathe for as long as it takes to accelerate, then it can let the upper rocket stage finish the job.

    • by 4D6963 (933028)

      Scramjet tech is worthless. It's not a very good weapon - a scramjet is going to have one heck of a heat signature and probably can't be very stealthy. Not just from the exhaust...at Mach 6 the entire aircraft/missile is going to be glowing red from heat. Also, air to air missiles (like the Patriot) that use rockets already go that fast.

      It's a moot point. You can't intercept something that fast, even if it's easy to see. It's hard enough to intercept a missile that doesn't go that fast..

      By the way, isn'

    • Second, it's worthless for getting stuff into orbit. The reason is simple - the reason a rocket costs so darn much has nothing to do with fuel. It has to do with complexity - it's very expensive to make something as complicated as a rocket work under all the stresses of a launch. A scramjet just worsens the problem. It's not the fuel or the size of the tankage that makes the rockets that SpaceX builds cost so much. It has to do with building the rocket well enough that it makes it and doesn't fail (again).

  • Hey, Ridley, ya got any Beeman's?
  • The Falcon [wired.com] is a DARPA vehicle that looks a lot more practical.

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