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Why are rockets round?

  1. Jan 30, 2010 #1
    Why are rockets round? Why not triangular, would it not be easier to make in some ways?
     
  2. jcsd
  3. Jan 30, 2010 #2

    turbo

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    Cylindrical structures have the least surface area for the enclosed volume, and they are very strong.
     
  4. Jan 30, 2010 #3

    FredGarvin

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    Minimization of weight as well as pressure vessels do not like sharp corners. Also, rockets do have to fly through our atmosphere before entering space so there is need for aerodynamic stability.
     
  5. Feb 1, 2010 #4

    minger

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    I've recently seen a design by a major airframer that used a trapdezodial body shape. I can't remember the reasonings, I would assume packaging, but I believe that there were aerodynamic reasons as well. I can't remember the program, but I think it's findable through Google.
     
  6. Feb 6, 2010 #5
    Probably the implementation of a 'lifting body'.

    KM
     
  7. Feb 6, 2010 #6

    Doug Huffman

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    What's a 'rocket' that the Space Scuttle is not, and it is not 'round'? The Apollo Lunar Module was not round.
     
  8. Feb 6, 2010 #7

    FredGarvin

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    ...and the SRBs and the Saturn V that put them into space????
     
  9. Feb 6, 2010 #8

    Doug Huffman

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    I was looking for counterexamples to the universally quantified 'rockets [are] round'.

    As the ancillary machinery is conceptually removed, the limit is the nozzle and usually round for reasons cited above. But note the not-round thrust vectoring nozzles on high performance jet engines. Both rocket motors and jet engines are reaction motors.
     
  10. Feb 6, 2010 #9
    Based on the way physicists usually approach problems, one might wonder why they are cylindrical and not perfectly round, frictionless spheres?
     
  11. Feb 6, 2010 #10

    FredGarvin

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    The design criteria for a thrust vectoring nozzle and a rocket nozzle are drastically different. The only thing they have in common is the fact that they are attached to a propulsion device. Just about the only rocket nozzle that isn't round is the aerospike and that has never flown.
     
  12. Feb 6, 2010 #11

    Doug Huffman

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    They're not both reaction motors?

    An "aerospike", indeed, many Trident SLBM have flown.
     
  13. Feb 6, 2010 #12

    Doug Huffman

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    Cruise missiles Taurus, AGM-86s ALCM, Storm Shadow; all subsonic powered by air breathing reaction motors.
     
  14. Feb 6, 2010 #13

    FredGarvin

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    And have nothing to do with being a rocket. Again, just because they are reaction propulsion, they are completely different in their operation and environment.
     
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