Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Giant nuclear powered combustion engine

  1. Jul 14, 2005 #1
    Has enyone (in the realm of fiction even) proposed making an enourmous
    piston engine that would use nuclear weapons instead of atomized
    hydrocarbons? (Sure, it would have to be BIG. But its possible, no?)
    Last edited: Jul 14, 2005
  2. jcsd
  3. Jul 14, 2005 #2
    You could consider Project ORION a nuclear-piston engine, without the engine-proper. :tongue:
  4. Jul 14, 2005 #3


    User Avatar
    Science Advisor


    With the exception of Project ORION - in which a spacecraft is propelled
    by ejecting a nuclear weapon and when the weapon exploded some distance
    away and some momentum recovered by a big "pusher plate" - I would say
    that a nuclear piston engine is NOT possible.

    The problem is that any nuclear explosion; even the smallest that we could
    ever make; is much too large and hot to contain with any kind of piston
    and cylinder as in an engine.

    In ORION, one only recovers a portion of the energy - which saves the ship.

    The "first wall" of any type of piston engine is going to be vaporized
    when it sees the nuclear device explode. [ It's a tough enough job to
    consruct the "first wall" for a BB-sized fusion capsule. ]

    Dr. Gregory Greenman
  5. Jul 15, 2005 #4
    Yet the Orion pusher plate would not be vaporized.
  6. Jul 15, 2005 #5
    Project Pacer fitted with piston engines instead of turbines

    I would call it a reciprocating heat engine. I suspect the reason why nuclear-powered reciprocating heat engines have not been theorized is that turbines tend to be more efficient. There are designs for nuclear explosions powering turbines. Richard Garwin described one called Project Pacer in his book https://www.amazon.com/exec/obidos/tg/detail/-/0375403949. That design involved a large excavated cavern lined with steel and fitted with turbines. Water is injected in-between explosions. This helps keep things cool and provides steam for the turbines. Explosions occur once per day. Fusion bombs are used, instead of fission bombs, for greater efficiency. 365 fusion bombs are used per year.

    If you could make a fusion-explosion turbine power plant such as this, there seems to be no reason why you could not make a fusion-explosion reciprocating power plant. There would be a difference, though, in that you are thinking of one giant piston, whereas a truer analog of the Project Pacer power plant would be a steel-lined cavity with many small reciprocating steam engines fitted to it.
    Last edited by a moderator: May 2, 2017
  7. Nov 25, 2009 #6
    what if instead of turbines or pistons couldnt u contain such a blast with an electromagnetic field then as far as heat goes couldnt u use that new metal we discovered called carbon carbon which is supposed to with stand the heat of the sun?
  8. Nov 25, 2009 #7


    User Avatar
    Science Advisor
    Gold Member

    Well I suppose you could make a fission-powered piston engine if you use very small amounts of fissile material and an external neutron source to "ignite" it. How to get a very high flux of thermal neutrons that you can turn on and off on demand without using more energy then the engine makes would be a problem though.
  9. Nov 26, 2009 #8
    Even if you could get it to work, wouldn't the amount of energy you'd need to create, move and detonate the nuclear devices severely offset the total efficiency of the whole process?
  10. Nov 26, 2009 #9
    With Orion they allowed for some ablation of the pusher plate, but even that was minimized by spraying a thin layer of oil on the plate before each shot.

    You can read some details here:
    http://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion)" [Broken]

    There are some nice illustrations here:
    http://www.flickr.com/photos/xeni/sets/72157594329917915/" [Broken]

    There is also a book: Project Orion: The True Story of the Atomic Spaceship By George Dyson
    Last edited by a moderator: May 4, 2017
  11. Nov 26, 2009 #10


    User Avatar
    Staff Emeritus
    Science Advisor

    Orion was problematic for a number of reasons - mass of a huge number of detonators being one.

    Please also note that the thread to which robo warrior responded has a last post of Jul15-05. It is 4 years, 4 months old.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook