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Aerospace Preventing Shockwaves from Supersonic Flight

  1. Jul 31, 2009 #1
    Oki well ill start with a little background so you know just about me :) Im studying aero engineering in Sydney Uni and second year student so i havent really hit all the Flight Mechanics and aerodynamics yet that comes next year but i was talking in a laboratory with a 4th year student (we were building a kit Jabiru J160) and he said someone was doing a thesis on how to stop the shockwaves from supersonic flight from reaching the ground.

    Having done a little bit of reading into ram and scramjet engines and the extreme speeds they are able to reach, an aircraft which was not restricted by its shockwaves could easily fly many times faster than what we have now. From what i know (yeah its basic) but there are 2 shockwaves from supersonic flight the bow shock and termination shock (correct me if im wrong please im always willing to learn super and transsonic flight stuff) so is it actually possible to redesign an aircraft to deflect shockwaves up into the atmosphere or stop them completely in the future? maybe with all these materials that change shape when a current is applied?
     
  2. jcsd
  3. Aug 3, 2009 #2
    Just had a quick think about it. I don't think you can stop shockwaves from being generated completely, but you could probably direct (deflect) them in a certain direction. That would entail geometry to be set up correctly or deflecting geometry to be added the vehicle.

    Shockwaves are caused by the information of the influence of the travelling body not being able to travel to the oncoming fluid quick enough for it to react causing a sudden change of pressure/temperature/density. When objects travel supersonically (or even transonically, but with local supersonic zones aorund the object, like in airfoils) it generates a shock wave. I don't think there is a way to prevent this from happening except by being able to transer information to the oncoming flow prematurely somehow.
     
  4. Aug 3, 2009 #3

    minger

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    There has already been much research done in this area. I believe the approach is not to stop them from happening; I'm not sure this can be done. Rather the approach is to "smooth" out the discontinuity that happens as the shock wave travels.
     
  5. Aug 3, 2009 #4

    Danger

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    I heard about 35 years ago (and incorporated into my novel) that applying a very high voltage (+/- 10,000,000 V) charge to the fusilage will split impinging air molecules apart and prevent shockwave formation. I don't know whether or not that's true.
     
  6. Aug 4, 2009 #5
    you mean generate some sort of plasma around the aircraft. I researched that topic a little bit for a plasma stealth application. The problem is the weight of the equipment required to generate that sustained voltage and general all round safety issues.
     
  7. Aug 4, 2009 #6

    Danger

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    Ah, yes... therein lies the nasty difference between fiction and reality. The power source for the aeroplane that I designed is a beta-source generator consisting of 550 lbs. of cobalt 60, which puts out, if I recall correctly, something on the order of 20 MW. The average Joe probably doesn't have that lying around in his garage. :wink:
     
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