Define what a Surface-Piercing propeller is

Discussion in 'Propulsion' started by tom kane, Jul 12, 2009.

  1. ChrisN67
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    ChrisN67 Senior Member

    Very well spoken position. I agree that thrust is the result of a system or the synergy of multiple, quite different, mechanisms.

    This whole thread initiated when I stated my surprise to a comment from a well known prop shop and very experienced engineer that the low pressure generated by the foil contributes a substantial component of overall propulsive force.
     
  2. tom kane
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    tom kane Senior Member

    The lateral flipping is related to rotational torque similar to the powerful ww11
    spitfire and other fighters rolling the body (prop walk) of the craft on take of. If they had of been designed non-symetrical to allow for the effect of rotational torque all would have been well, instead the craft had to look symetrical (big mistake of Human beings) so many expert heros died as a result.
     
    Last edited: Jul 1, 2014
  3. powerabout
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    powerabout Senior Member

  4. ChrisN67
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    ChrisN67 Senior Member

    SBM surface drives on a modified Intrepid 339 (Now 39')

    https://www.youtube.com/watch?v=E4l4ATbv-Eg

    https://www.youtube.com/watch?v=9zUBX2KUtMQ

    https://www.youtube.com/watch?v=9zUBX2KUtMQ

    16750 dry weight

    With 250 gallons fuel, 5 persons an 42 C ambient temperature 27 C Sea Temp

    44 Knots First gear; 51 knots second gear

    Problems:
    On plane over 45 knts steering is very slow (about 8 degrees per second)
    Cannot hold speed between 10 and 20 knts during transition to plane
    When docking reverse has 30% of forward thrust
     

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  5. tom kane
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    tom kane Senior Member

    Have we really progressed in surface piercing propeller design ? Hickman`s sea sled could do over 50 HPH using slow RPM heavy engines and no conventional rudders and the way it worked seems to me a lot different to the modern S/P propellers which probably create more drag and are more better used in food processors.
    Some of the comments about a " propeller not looking like a S/P propeller " shows that a any propeller can be used in S/P mode.
     

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  6. powerabout
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    powerabout Senior Member

    I dont think we yet know how a prop works.
    The other day a prop manufacturer told me a customer brought his world record prop in, they scan it and it has 3 different blades. ( normal)
    They them make 3 props, using one each of the blade designs so they have 3 identical blades on 3 different props
    The original prop still faster
     
  7. tom kane
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    tom kane Senior Member

    All the information and design of propellers seems to be a copy of what someone else has done in the past with some hopeful tweeks and twists looking for better results and hopefully something to Patent.
    Most information is specific to traditional practice and mis-conceptions and not wanting to step out of line with what "looks like it will do a good job". When general practice in design understands Quantum Mechanics perhaps there may be improvements.
     
  8. sandhammaren05
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    sandhammaren05 Senior Member

    Off the wall. You cannot derive macroscopic classical behavior from quantum mechanics. I'm not writing about what other people have done, otherwise, I'd watch TV instead of working and writing.
     
  9. gonzo
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    gonzo Senior Member

    In Quantum Mechanics particles appear and disappear. It would be really annoying to have propeller blades behave like that.
     
  10. sandhammaren05
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    sandhammaren05 Senior Member

    Massive particles disappear while conserving mass only in relativistic quantum field theory. There is no quantum coherence macroscopically, and quantum mechanics cannot describe macroscopic phenomena. We have understood that since 1930. The exceptions where coherence is exhibited macroscopically are superfluidity and superconductivity. Quantum teleportation has nothing to do with boat design. I suggest that the pundits read some popular texts on qm instead of posting irrelevant notes on the boat design website.
     
  11. tom kane
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    tom kane Senior Member

    It is not a good idea to quote what was known in the 1930`s about Quantum Theory now much new information has come to hand and the 30`s is very past knowledge.
    How sub-atomic particles behave runs hand in hand with Classic Mechanics?.
    Small is just part of big.
     
  12. sandhammaren05
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    sandhammaren05 Senior Member

    Tom, do you know what you're talking about? The explanation by Dirac in the intro to his 1930 book on qm is exactly the description of quantum coherence that we tech and use today. QFT and new particles at high energies do not in any way change that. The big part of the picture is quantum coherence. Have you read and understood the old Einstein-Podolsky-Rosen paper, the basis for quantum teleportation-?! Or are you shooting from the hip while wearing a blindfold!?
     
  13. ChrisN67
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    ChrisN67 Senior Member

    Wow, I only got half way through those big words and decided to go out and catch some big fish.
     
  14. tom kane
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    tom kane Senior Member

    I am very cautious about all information put forward by the Scientific and Arts and Design and any expert fields where Mind Enhancing drugs play a part in their " inspirational " theories.
    A majority these people admit to using them. If Einstein claims to not understand Quantum Theory what chance has anyone else and his "famous' equation has not and can not be proven. Give me an observable experiment proving claims then I may grudgingly acknowledge something as being factual.

    Buying a Surface Piercing propeller is just like shopping for Alternative medicine there are plenty of cures available but do any have any real value other than creating an income for some speculator businessman.

    Science is at a stage where answers can not be proven so we are expected to just accept Theory as fact form all those who put them forward.

    If you think your knowledge is the only right way forward I am happy for you and thank`s for your discussions on this thread topic. Show me your definition of a surface piercing propeller, but first Google Images, Surface Piercing boat propellers to see many of the designs and applications there are few if any like Hickman`s and yet he achieved speed.

    www.freeradicalsbook.com
     
    Last edited: Feb 2, 2015

  15. tom kane
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    tom kane Senior Member

    I hope you caught some big fish but did not mean you where going phishing.
     
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