18 thoughts on “Yet Another Scramjet To Orbit”

  1. Where is the fourth SCRAM-Jet engine in that oh-so-lifelike rendering of the vehicle? There are only 3 intakes and outlets on the bottom of the craft, but the caption clearly states that “The underside of the second-stage Spartan vehicle under development is equipped with quad 3D scramjets” (emphasis mine).

    Honestly, that rendering reminds me of the 90s game Spectre for the Macintosh.

    Do people really take those sorts of stories seriously?

    1. I looked at the image. The nearest intake and exhaust are more side-mounted than bottom-mounted:

        O           O
            O   O

      Taking that into account it appears some of the farthest intake and exhaust are visible, but mostly hidden because of the perspective of that particular rendering.

      (I shall now press “Post Comment,” praying that the HTML posts exactly as it appears in the live preview.)

    2. Well, obviously it’s on the far side, out of view. The belly of this beast is quite round.

      You know somebody is bound to make it work – eventually – 😉

      1. They sure would be, especially with liquid hydrogen.

        But if they are only going mach 4.5, wouldn’t liquid methane work? Might help somewhat. And with 24 passengers, a somewhat more elite crowd than even the Concord. Plus package delivery.

      2. They sure would be, especially with liquid hydrogen.

        But if they are only going mach 4.5, wouldn’t liquid methane work? Might help somewhat. And with 24 passengers, a somewhat more elite crowd than even the Concord. Plus package delivery.

  2. The one (and only) think I like about their concept is the use of a propeller to get the first stage back to the launch point. The piston engine is weird, though, since a turbo-prop would be much lighter. An empty first stage is going to fly very slowly, no matter how small the wings are, and a propeller is the very best match power-wise. I’ve proposed the same thing in the past, and received snickers from technical ignorami.

    But, yeah, scramjets are the technology of the future…and always will be.

        1. The primary application for ScramJet technology in Australia is to busy the hands of engineering students and lengthen the publications list of academics.
          I wouldn’t diss you guys so easily. It’s true that there is basically no market for such a thing in Australia, as usual, even if it worked. Which does not mean that they won’t get it working. Wouldn’t be the first time something gets developed in Australia and commercialized elsewhere.

  3. Scamjet to accelerate from Mach 5 to Mach 10, Which a Kero/LOX rocket can do with a mass ratio of 1.6 at that altitude. I wonder if that scamjet stage is going to be cheaper than the larger tanks a rocket would have.

      1. Rand, surely saving about 20% of the oxidizer mass needed to get a pound of payload to orbit is worth increasing the total vehicle pad mass by 60%?

        /lefty economics mode.

        🙂

        1. In principle it’s a good idea. The problem is how to collect that 20% mass of oxidizer. Let’s say you increase the size of the air intakes. You probably just increased drag and aircraft mass. Let’s say you need to glide around for a while to collect that oxidizer. You probably just added a requirement of wings (i.e. more extra mass) to the launch vehicle. Then there is the small nag that air is low density compared with liquid oxygen so you need bigger and heavier oxidizer tanks. Eventually you figure out that you need more fuel to spend all that time gliding as well. Then you account for gravity losses for not doing a vertical ascent.
          Oh and the scramjet can’t start until the craft reaches Mach 5 and it can’t do the last stretch to space because there is no atmosphere. A rocket engine can work all the way from ground level to space. Then you realize you were better off using a rocket.

          Mind you there were proposals at one point in the 1950s or whatever to use so called LACE technology i.e. Liquid Air Cycle Engines. It’s basically a LOX/LH2 rocket with an air collector and liquefying unit. Also sounds great in principle until you realize you can’t build something like that which can lift its own weight let alone get into space. Refrigeration equipment isn’t that compact and lightweight. If you want to read something more modern about that check out HOTOL, and Skylon.

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