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Propulsion physics question

  1. Jul 27, 2015 #1
    This is probably the wrong section for this question but what area of physics is propulsion physics. For rockets and stuff. Would that be considered nuclear physics?
  2. jcsd
  3. Jul 27, 2015 #2
    No, the physics of propulsion is classical Newtonian physics.
    Apply a known force to something and it moves in a predictable way.
    Rocketry is a just a specialisation within that.
  4. Jul 28, 2015 #3


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    It has elements of nuclear physics if the suggested rocket type uses nuclear reactions. No existing rocket does that, but some concepts do.
    The motion of the rocket is purely classical mechanics.
  5. Jul 28, 2015 #4
  6. Jul 28, 2015 #5
    I have heard of such concepts, but I don't feel safe with the idea of being accelerated by carefully timed nuclear detonations.
  7. Jul 29, 2015 #6
    But you feel comfortable being sustained and nourished by a huge continuous runaway fusion reaction at the center of our solar system? :wink:

    BTW, they also have concepts and even successfully tested nuclear rockets that work on a controlled reaction, such as in a power plant.
  8. Jul 29, 2015 #7
    The Sun is not a runaway reaction it's fairly stable and predictable and is 150 million km away - but even then it emits occasional outbursts of matter and radiation which are not predictable, and definitely hazardous to be exposed to.
    Having said that though, if a fusion reactor could be be made small enough, and we had a technology that would convert it's output into directional thrust, and the payload could be adequately shielded from neutron bombardment - well it might be runner, but that's a lot of tech which is way beyond our present abilities.

    The nuclear rocket concepts I have heard of so far involve something along the lines of detonating several fission bombs in sequence behind the rocket which would then 'surf' along on the shockwaves created. That's what I'm not too keen on the idea of.
  9. Jul 29, 2015 #8
  10. Jul 29, 2015 #9
    I had not come across that one before but it does sound more realistic than the shockwave surfing concept.
    I did a quick search and discovered that a proof of concept NERVA prototype was built, which although it had some engineering hurdles to overcome these were not insurmountable.
    It's not too clear from my quick search as to why the project was abandoned.
    Last edited: Jul 29, 2015
  11. Jul 29, 2015 #10
    The shockwave surfing concept was actually surprisingly well developed, but got axed because of the partial test ban treaty. The NERVA I'm not sure either...some political reasons I guess. In the end, public opinion is that nuclear = bad, and therefore either one has a slim chance of being resurrected anytime soon.
  12. Jul 29, 2015 #11
    I'm not sure which ideas you've come across in the past, but here are several:


    There was an interesting experiment back in the 60's I think called Project Pluto to develop a nuclear powered cruise missile. It didn't use nuclear explosions to power it, but it used a nuclear reactor to provide power to a continuously running ramjet engine. Though this isn't what you were talking about earlier, it still would technically fall under the description 'nuclear powered propulsion'. If you look at it from that perspective, it opens up some other options that maybe you hadn't considered:

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