Is Super Cavitation Possible?

Discussion in 'Architecture & Engineering' started by Danny G, May 17, 2010.

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  1. Danny G "Listen.. you smell something" Registered Senior Member

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    Just Read "The Tomb of Hercules" By Andy Mcdermot, and in the book he mentions a Submarine that has a squared off nose that creates a cavity of pressure around the craft at high speed, reducing the friction.

    Just wondering if this sort of super high speed Submarine Idea is possible? or is in use anywhere (torpedoes?)
     
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  3. fedr808 1100101 Valued Senior Member

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    I doubt it for submarines. Namely because you need rocket propulsion to power it and to move something of that mass fast enough I can't imagine you could store that much fuel to go any farther than 50 kilometers, but more likely around 7 km.

    But there is a torpedo made by Russia called the SHKVAL that does accomplish super cavitation.
    http://en.wikipedia.org/wiki/VA-111_Shkval

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  5. Danny G "Listen.. you smell something" Registered Senior Member

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    wow, thanks for that link, 200kts underwater, i thought that was impossible before now.
     
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  7. fedr808 1100101 Valued Senior Member

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    yah, its basically a missile flying underwater.
     
  8. kmguru Staff Member

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    You can do that for a submarine, but the energy needs will be very high making the process impractical, unless you want to move a short distance with high speed.
     
  9. fedr808 1100101 Valued Senior Member

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    Precisely.

    Km, I know that originally the SHKVAL was unguided, but they created control surfaces by extending fins into the water just outside of the bubble.

    I know that with solid fuel and liquid fuel rockets they can steer somewhat by actually manipulating which way the funnel faces that the flames shoot out of, tell me, what is keeping supercavitating torpedos from using something similar?

    Do you think it is because the response time and turning radius would be poor?
     
  10. Omega133 Aus der Dunkelheit Valued Senior Member

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    Well, I don't know much about torpedoes, but I do know that the faster something goes, the harder it is to maneuver. (Exception with jets)
     
  11. Dywyddyr Penguinaciously duckalicious. Valued Senior Member

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    Not even.

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    There is a control problem at low speed with aircraft, but that's due to lack of sufficient airflow over the control surfaces to provide the required authority.
    But the faster a jet goes the harder it is to deflect from its course. And the greater the stresses induced when you do manage to do so.
     
  12. Omega133 Aus der Dunkelheit Valued Senior Member

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    Hey, I was right.
     
  13. John99 Banned Banned

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    Cars\Motorcycles?
     
  14. Omega133 Aus der Dunkelheit Valued Senior Member

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    Especially Cars/Motorcycles. The faster you go in a car the wider the turns have to be. Same with motorcycles.
     
  15. John99 Banned Banned

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    They maneuver better and turn easier at high rates of speed and under power. You are pointing out limitations in the tires.
     
  16. Omega133 Aus der Dunkelheit Valued Senior Member

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    Wrong. A car takes quite a while to turn, and even then it has to be a wide turn. It's all about momentum. To suddenly change direction makes the car skid/drift.
     
  17. John99 Banned Banned

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    That is due, as i said, to limitations in the tires. One experiment is to try and turn a motorcycle by leaning alone. You can do this the faster you go but if you are going very slow? That is due to momentum.
     
  18. Omega133 Aus der Dunkelheit Valued Senior Member

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    Ok. I see your point. But it's still hard to turn, no matter the cause is.
     
  19. John99 Banned Banned

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    I am going off the top of my head here but the OP is not about cavitation. Lets see how good my memory is.
     
  20. John99 Banned Banned

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    Its funny because i think he got the term from superheating. You would not want super cavitation. I could be wrong though because i am going off a definition i have in my mind.
     
  21. Dywyddyr Penguinaciously duckalicious. Valued Senior Member

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    Off the top of my head you're wrong:

    No it's not from superheating, it's a well-known phenomenon that is "super", i.e. over and above, normal cavitation.
    And yes, you would want supercavitaion, it causes less drag than normal cavitation.

    You are wrong. Why not use the actual definition?
     
  22. Dywyddyr Penguinaciously duckalicious. Valued Senior Member

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    They appear to, but that is a control problem. E.g. at low speed it's a question of keeping balance. But the faster they go they greater the radius of turn (i.e. the less manoeuvrable they are).
     
  23. phlogistician Banned Banned

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    Did you ever see the 'Mythbusters' episode, where they tried to recreate the 'Batman' cornering grapple hook scene?

    The managed to fire a grappling hook and to get it to attach to a structure OK, but even at moderate speed, the cables were just under too much stress and broke. Tight cornering and G-Forces, are a bitch.
     
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