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Are Ionospheric Scramjets possible?

  1. Feb 8, 2014 #1
    I was doing some Wikipedia browsing, and I came across the concept of Scramjets for spaceplanes. The highest estimate for a top speed of a scramjet in atmosphere is Mach 25, which is approximately orbital velocity. The ionosphere contains high levels of O, so would it be possible to fly a scramjet aircraft in it (at approx. 100km)?
     
  2. jcsd
  3. Feb 8, 2014 #2

    mfb

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    High fraction does not mean high amount - the ionosphere is extremely thin. You don't get much oxygen there, and not much lift. You need a very high speed to counter this. 100km is at the Kármán line, where the required flight speed reaches the orbital speed - your "plane" becomes a satellite.
     
  4. Feb 8, 2014 #3
    Thanks. Thing is that at Mach 25, surely even though it is very thin, you are taking in some? Do you know if such a scramjet would work, even if it had very low thrust? And for the sake of the theory, assume that there is no drag.
     
  5. Feb 8, 2014 #4

    mfb

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    I'm sure you can burn something, but airplanes are always a quantitative problem.
    The air is thin, but at that speed drag is relevant.
     
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